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Vol 1, No 2 (2013)

Courtesy of the Robert Pope Foundation

An open access, online journal covering all aspects of pain

ISSN 2047-0800


Vol 1, No 2 (2013) April 2013

Editor-in-Chief Dr Rajesh Munglani Pain Medicine Consultant

The Journal has been created in recognition of the fact that not all information or advances in pain medicine can be presented in a randomised controlled fashion.

The editor welcomes contributions. Please email kate@joopm.com to submit an article for consideration or to join our mailing list.

The Journal will publish papers on clinical practice, basic science, ethics and medico-legal aspects of pain. Issues around suffering, theological, social, psychiatric, psychological, education and resources limitations in pain medicine will also be considered.

www.joopm.com email: info@joopm.com Editorial Board

Contents

Assistant Editor-in Chief Dr Turo Juhani Nurmikko

Sublingual ketamine in chronic pain : service evaluation by examining over 200 patient years of data V.K Jailty

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Establishing a pain service in the community Barbara Hoggart, Eve Jenner, Patrick Hill

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Pain perception in altered states of consciousness Laura Munglani

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Communication with pain in mind: commentary M.D. Spencer

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Looking for Idiopathic Intracranial hypertension in patients with chronic fatigue syndrome Nicholas Higgins, John Pickard, Andrew Lever

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Can the MMPI-2 detect exaggeration in personal injury cases? A brief outline Kari Carstairs

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Surgery for lumbar Intervertebral disc prolapse in a patient with complex regional pain syndrome Christopher Green, George Evans

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The incidence of complex regional pain syndrome (CRPS) post trauma and the possible role of tight plaster of Paris in the aetiology of CRPS Zahra Safarfashandi, Rajesh Munglani, Laila Safarfashandi Jamie Sadheura, Christopher Jenner

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Peripheral nerve field stimulation for post-surgical neuropathic pain: correlation between quantitative sensory testing and efficacy two years post implantation Manohar Lal Sharma, Devjit Srivastava, Jibril Farah Mark Draper, Manish Gupta

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Assistant Editors Dr Joshua Adedokun Dr Ganesan Baranidharan Dr Arun Kumar Bhaskar Revd Dr Mark Quinn Bratton Rev Canon Dr Adrian Francis Chatfield Dr Neil Collighan Dr Andrew Cooper Dr Simon Dolin Mr Marcus Grant Dr Sanjeeva Gupta Dr Shamim Haider Dr Dalvina E. Hanu-Cernat Dr Andrew Lawson Dr Kevin Markham Dr Patrick McGowan Dr Vivek Mehta Dr Charles Pither Dr Andrew Ravenscroft Dr Jonathan Richardson Dr Manohar Lal Sharma Dr Michael D. Spencer Dr Simon James Thomson Pain Fellow Representative Dr Kiran Sachane Copy Editor Paul Nash Journal Manager Ms Kate Dougherty KJD Communications www.kjdcommunications.com

Sciatic nerve palsy following sacroiliac joint injection Catherine Gwilt, Neil Collighan

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Ophthalmic post-herpetic neuralgia Sophie M. Shotter, Neil Collighan

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ISSN 2047-0800


Sublingual ketamine in chronic pain: service evaluation by examining more than 200 patient years of data Dr V. K. Jaitly MB ChB FRCA FFPMRCA

1

Abstract I present more than 200 patient years of observational data, including Brief Pain Index (BPI) outcomes on patients who have found sublingual ketamine useful to help manage their pain symptoms. Data was obtained from our Pain Audit Collection System (PACS),1 a review of the local Electronic Patient Record (EPR) and a separate bespoke database. The observations and treatment took place at an NHS district general hospital multidisciplinary pain clinic in England from 1 January 2000 onwards. Data was locked down on 1 March 2012 to allow analysis to be undertaken. Out of 249 patients tried with ketamine, 95 patients found it of little use on the day that they tried it. A further 107 patients took ketamine for as little as one month up to as long as seven years before stopping it. At the time of data analysis, 47 patients were still taking sublingual ketamine. 32 of these 47 patients had been taking sublingual ketamine for more than two years. The PACS Treatment Assessment Form consists of the BPI questionnaire and also asks one additional question: ‘In the last

week, how much relief have pain treatment or medications, obtained from this clinic, provided? Please circle the one percentage that most shows how much relief you have received.’ In the 32 patients, who had been taking ketamine for more than two years, ketamine did not consistently improve BPI scores, but these patients did report pain relief when taking ketamine. The modal pain relief score reported by each patient was determined. The mean of all 32 modal pain relief scores was approximately 56% pain relief. As ketamine was often tried in combination with other pain treatment modalities, the observations made may be confounded by the effects of other pain treatments. At the doses used in my practice, no patient in this series has developed ulcerative cystitis. I conclude that when used carefully, low-dose ketamine can have a useful role to play in the management of chronic pain. Keywords Ketamine, chronic pain, service evaluation, long-term safety data

Introduction Ketamine is a drug of abuse, a dance-floor drug and a date-rape drug.2,3 It is also an anaesthetic drug with analgesic properties.4 The use of ketamine to manage chronic pain is controversial.5,6 Anecdotal case reports suggest that ketamine may be a simple and useful treatment option to help patients manage their chronic pain,7 particularly when other treatments have not proved useful. On the other hand, concerns have been raised that ketamine can cause liver and urinary tract damage and critics also point to a lack of gold standard randomised controlled studies to support its use and to a lack of long-term safety data.6,8 In a review of scientific evidence for acute pain 1

Department of Anaesthesia, Wrightington Wigan and Leigh NHS Foundation Trust, Royal Albert Edward Infirmary, Wigan Lane, Wigan WN1 1NN, UK. Journal of Observational Pain Medicine – Volume 1, Number 2 (2013) ISSN 2047-0800


management, the findings of a working group of the Australian and New Zealand College of Anaesthetists and Faculty of Pain Medicine supported the use of ketamine in some acute pain situations.9 With respect to chronic pain, opinions in review articles have ranged from ‘… in situations where standard analgesic options have failed, ketamine is a reasonable third line option’5 to ‘while the current literature provides evidence for acute relief of chronic non-cancer pain, information supporting the efficacy and tolerability of ketamine in the long-term treatment of chronic pain is extremely limited’.6 Arguments are also made that any benefit patients experience are probably placebo (Wells, C., ‘communication’ on pain consultants Google group). Patients attending my chronic pain service are offered a range of treatment modalities, including Transcutaneous Nerve Stimulation (TNS), acupuncture, groupbased and individual exercise programmes, pain management programmes and injection-based approaches, and are offered input from psychology and occupational therapy. Onward referral to a tertiary centre is also possible and, of course, drug interventions are also offered. In 1999, the evidence-based drug treatments in vogue were capsaicin ointment, amitriptyline (and other antidepressants), and carbamazepine10 (gabapentin was being used on an unlicensed basis back then, as were other anti-epileptics). At that time, the majority of drugs available for chronic pain were unlicensed, or had very specific licensed indications. Once these drugs had been tried, there were few other drugs to try apart from opioids, and much like today, clinicians and patients alike were wary of commencing these. Inevitably back then, as is the case currently, some patients were not prepared to accept that there was nothing else that could be done for their pain, and these patients were not ready to progress to a pain management programme. It was in this context that I came across the 1999 publication by Batchelor11 where he recounted his experience of using the drug in patients over a period of five years. Shortly after publication of this article I tried ketamine in a patient who had tried all other treatment modalities available to me. The patient reported good pain relief so I have continued to try other patients with this drug over the years. As I routinely collect outcome data for all my patients using the PACS database, I decided after several years to evaluate outcomes of patients who have been through my service and tried ketamine. After this initial evaluation and following the reports of ketamineinduced ulcerative cystitis,12 I then created a bespoke simple database to allow me to systematically track who had received ketamine and how they had fared as part of a continuous audit process. As there is a dearth of information regarding long-term outcome data in patients who use ketamine as an adjunct in their management of chronic pain,6 I hope this paper will shed some light on this neglected area of study.

Methods The clinical director of our local research and development department has confirmed that because this paper consists of service evaluation and audit, no ethics committee approval was required.

Ketamine administration After appropriate counselling in the outpatients (where patients are given a patient information leaflet13 and are informed that ketamine is also known as a drug of misuse, a date-rape drug, a dance-floor drug, a horse anaesthetic and a human anaesthetic which might make them hallucinate and has a poor success rate in the management of chronic pain), patients are listed for a trial of oral ketamine (technically it is sublingual administration but it is easier for everyone to say the word ‘oral’ rather than ‘sublingual’). As patients have access to the Internet these days, I feel they are better off hearing this information from me rather than reading 4

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about it online and then possibly feeling that I was hiding this information from them. Most patients are considered to be eligible for consideration for ketamine treatment. Patients with a history of substance misuse and female patients of childbearing age who are yet to complete their family are not usually offered this treatment modality. Patients who wish to try ketamine are asked to attend the Day Surgical Unit (DSU) on the day that I carry out my injection list. The ketamine is administered prior to starting the injection list. If possible, patients are admitted to a quiet side room on our DSU. I ask patients to take all their regular painkillers as normal (so I can judge better the interaction between these drugs and the ketamine). Prior to asking a patient to sign their ‘NHS Informed Consent Form 3’,14 I ask the patient to numerically rate their pain score (0–10) and I make a note of this. I then administer the sublingual ketamine (Pfizer Limited, Sandwich, Kent CT13 9NJ, UK). It is the intravenous preparation that I use. For many years it has been the 100 mg/ml preparation that has been used but, more recently, manufacturing has been relocated and stocks are running low (personal communication from pharmacy) so currently we have been using the 50 mg/ml preparation. The usual dose is 20 mg and I ask the patient to hold it sublingually as long as they can, and inform them that they can swallow if they feel they are going to drown in their own saliva. After completing my injection list I return to review the patient. I ask the patient if they have had any benefit and ask them to numerically rate their pain score again on the same 0– 10 scale. It is clearly easier to judge the utility of the ketamine if the pain is constant rather than episodic. Patients are asked to complete a ketamine treatment agreement (Appendix A) if they appear to have found the ketamine helpful. One copy of the agreement is given to the patient and the other is filed in the medical records. I ask patients to demonstrate using tap water that they can successfully draw up and self administer the correct amount of drug before discharge. Patients are given a 30-day supply of ketamine in a standard NHS drug dispensing bottle (the shelf life of ketamine in this bottle is only 30 days – personal communication from Trust pharmacist). The usual dose suggested to the patient is 20 mg to be taken three times per day via the sublingual route. Patients are advised that they can experiment a little with the dose but to not exceed the total daily dose of 60 mg per day. Suitable dose options could be 30 mg bd or a single maximum dose of 40 mg, with the remaining 20 mg either split into two doses of 10 mg, or one dose of 20 mg. Patients are requested to self-assess which dose regime appears to suit them and they are reviewed in the clinic four weeks later. If the ketamine is still helping at this stage, patients are initially reviewed again at three months, and if all is well at that point, patients are then reviewed on a six-monthly basis and repeat prescriptions issued at each outpatient visit. The medication is dispensed by the hospital pharmacy on a monthly basis.

Data collection and analysis I routinely attempt to collect outcome data for all patients who attend my service by means of using the PACS Treatment Assessment Form. This form consists of the BPI questionnaire and it also asks three additional questions, one of which is: ‘In the last

week, how much relief have pain treatment or medications, obtained from this clinic, provided? Please circle the one percentage that most shows how much relief you have received.’ Data from the paper form was then entered onto the PACS database by either myself or the specialist pain nurse. After carrying out my first audit in 2004, it became apparent that extracting information would be easier by setting up a simpler bespoke database. The spur to design and use such a database came in 2008 when reports emerged of renal tract problems associated with ketamine use.12 Microsoft 5

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Access® was used to design the database: data collected included the age, sex and name of the patient who had tried ketamine, the date they started treatment (data field [on it since]) and whether they were still on treatment. If the patient was still receiving ketamine treatment, a calculation was made of how many days the patient had been taking the ketamine by building the following expression in the field cell of a query: Int((Now()–[on it since])) . Summing this value for each patient and dividing by 365 calculated the total number of patient years of treatment. The audit standard for the 2008 audit that I carried out was that no patients receiving ketamine would have ulcerative cystitis. After consultation with a urology consultant, urine dipstick testing and biochemical profile were deemed to be the screening investigations of choice. Patients attending the clinic for ketamine review were informed of the possible issues and they were offered screening. Following the audit, the bespoke database continued to be used as a convenient means of being able to systematically audit patients who had tried ketamine. The PACS database also has a function that allows BPI scores to be viewed graphically as well as in tabular format. Both ways of viewing the data were extracted for the 32 patients who had been taking ketamine for more than two years. A separate worksheet for each patient was created in a Microsoft Excel® spreadsheet. Each worksheet contained the PACS data for each patient. The modal value for pain relief was determined for each patient. It was ensured that the modal value was only determined for observations made on dates after the ketamine was commenced. The modal value was put in cell A1 of each worksheet and the mean of all modal values was obtained. A copy of the spreadsheet will be made available online with this paper. In addition, the following information was collected using PACS and the EPR as source data: starting ketamine dose and current treatment dose; clinical diagnosis; biochemical profile where available; side effects noted; and other snippets of medical history where deemed relevant.

Results Figure 1 illustrates how patients progressed after having sublingual ketamine administered to them. As can be seen, at the time of data lockdown I had tried 249 patients with sublingual ketamine. 95 patients did not find it of any help at all when they were reviewed several hours after having it administered to them. 107 patients appeared to find the ketamine of some benefit, but abandoned the treatment at a variable interval after having been commenced on the drug. The bulk of patients who abandoned treatment did so within the first two years of trying the medication. Unfortunately, I did not systematically collect the reasons why the ketamine treatment had been abandoned in these patients. Eight patients who had been on regular ketamine died during the period being analysed. I am able to provide on request a list of when the ketamine was stopped. 47 patients were still taking ketamine when the data was locked down. Figure 2 shows the age and sex distribution of my 47 patients who were taking ketamine when the data was locked down. Figure 3 lists the diagnoses of the 47 patients still taking ketamine. As can be seen, patients with a range of diagnoses seem to have found some benefit. Of the 47 patients were still taking ketamine, 32 of these patients had been taking sublingual ketamine for more than two years. I looked at these 32 patients in greater detail. Table 1 shows the duration of treatment in these 32 patients, the age at which treatment was started, the sex of the patient, the starting dose of ketamine, the current dose of ketamine and the mode value of all the pain relief scores reported by each patient. The total duration of patient treatment was calculated to be more than

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200 years. If ketamine treatment was successful, the average pain relief that patients reported was calculated to be 50–60%. The standard for the 2008 ketamine audit was that no patient should have had ulcerative cystitis or renal impairment as a consequence of taking ketamine. This standard was met and Figure 4 highlights the findings of this audit. At that audit, it was noted that 5 out of 179 patients had experienced hallucinations of some sort and that two patients thought they were getting more forgetful. Since that audit, one patient has stopped taking ketamine because they were concerned that their memory was failing. Figure 1 – Flow chart illustrating how patients progressed after taking ketamine

249 patients try sublingual ketamine.

Did it help on the morning of taking the drug?

No

95 patients find it of no use on the morning of trying the drug.

Yes

Is patient still taking the ketamine?

Yes

47 patients are still taking the ketamine. 32 of these 47 have been taking it for more than two years.

7

No

107 patients took ketamine over a time period from as little as one month to up to as long as seven years before stopping. 8 of these patients stopped taking ketamine because they died – 4 cancer-related deaths, 1 patient with post-stroke pain died, 1 patient had a diabetes-related death and 2 patients died from other causes. Patients may also have stopped taking ketamine if the drug no longer helped them or if they got side effects.

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Figure 2 – Age/sex distribution of 47 patients taking ketamine. Age is the age at which the ketamine was started, not the patients’ current age

Figure 3 – Diagnoses of patients currently taking ketamine

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Table 1 – Patients who have been taking ketamine for more than two years: breakdown of age treatment started, sex, duration of treatment, starting dose of ketamine, current dose of ketamine and modal pain relief

Patient number

Patient 1 Patient 2 Patient 3

4448 4133 4126

Age ketamine was started 39 29 53

Patient 4 Patient 5 Patient 6

3630 3553 3532

35 36 48

male male male

1mg tid 15 mg tid 10 mg tid

Patient 14* Patient 7

3189 3089

33 38

female female

Patient 8

3042

47

male

15 mg tid 75 mg 5 times per day 10 mg tid

Patient 9 Patient 10 Patient 11 Patient 12 Patient 13 Patient 15 Patient 16 Patient 17 Patient 18 Patient 19 Patient 20 Patient 21 Patient 22 Patient 23 Patient 24 Patient 25 Patient 26 Patient 27

2965 2909 2909 2795 2795 2538 2412 2125 1894 1887 1817 1691 1488 1488 1404 1166 1166 1152

56 50 36 42 40 37 48 56 52 56 52 58 48 54 41 50 40 43

male female male male male female male male female male female male female female female female female female

20 mg tid 20 mg tid 20 mg tid 20 mg tid 20 mg tid 20 mg bd 20 mg tid 20 mg tid 20 mg tid 20 mg tid 20 mg tid 20 mg tid 20 mg tid 20 mg tid 20 mg tid 20 mg tid 20 mg tid 20 mg tid

Patient 28 Patient 29 Patient 30 Patient 31 Patient 32 Total patient days of treatment

1096 1005 956 956 921

56 42 42 63 36

female male female female male

10 mg bd 20 mg tid 30 mg bd 20 mg tid 20 mg tid

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Treatment duration (in days)

74 277

Sex

Starting dose of ketamine

Current dose of ketamine

male female male

10 mg tid 10 mg tid 10 mg tid

15 mg tid 30 mg tid 20 mg tid 15 mg bd 25 mg od 30 mg tid 50 mg nocte 90 mg in 24 hours 90 mg 7 times per day 140 mg nocte 10 mg tid (was higher but patient forgetful so dose decreased) 30 mg tid 30 mg tid 30 mg bd 30 mg tid 30 mg tid 30 mg tid 30 mg tid 30 mg tid 30 mg qid 30 mg tid 30 mg tid 30 mg tid 75 mg nocte 30 mg tid 20 mg tid 20 mg tid 20 mg tid 40 mg mane 50 mg nocte 20 mg bd 30 mg qid 30 mg tid 20 mg qid 30 mg tid

Average modal pain relief

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Modal pain relief (%) 70 20 80 70 60 70 40 60 20

60 60 60 50 70 30 60 60 60 70 50 50 50 90 50 60 90 60 50 50 60 20 50


Total patient years of treatment

203.5

* This patient was inadvertently given this patient number early on in data analysis – therefore, in order to not have to renumber all patients and confuse myself, identity maintained as patient 14. Figure 4 – Results of 2008 audit

Discussion Although the randomised controlled trial is the gold standard experimental design for testing a novel intervention, many areas of clinically important knowledge are best, or most efficiently, informed by high-quality observational data.15 I make no claim to have provided randomised controlled information or evidence in this paper – I have merely written about what I have observed when my patients have tried sublingual ketamine in an attempt to help them manage their pain. This data therefore comes with all the warnings and caveats that apply to this type of information. Anyone thinking about prescribing ketamine in the way that I have needs to answer for themselves the following questions: • Does ketamine work?

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56.25


• •

Is it safe? How do I use it?

This data suggests that about 1 in 5 patients seem to get some sort of benefit from ketamine in the long term. There is clearly a huge placebo effect and this is manifest by the number of patients who abandon treatment within the first few years of trying the drug. It is argued that the 1 in 5 patients who appear to have a long-lasting response to ketamine are also demonstrating a placebo response (Wells, C., communication on pain consultants Google group). While this may be the case, I would point out that the same patients did not elicit the same remarkably persisting ‘placebo’ response when they tried other evidence-based drugs like amitriptyline, duloxetine, gabapentin or pregabalin beforehand. When patients did report benefit, the average pain relief that patients reported was calculated to be 50–60%. However, the benefit reported does not appear to translate itself in the form of better BPI scores. Eyeballing the data does not show any clear pattern or trend with respect to pain scores or interference with various elements of the BPI. The question therefore that has to be asked is that if ketamine is not improving BPI, what is it really doing? It is possible that ketamine may be improving the low mood which often accompanies patients who have chronic pain. There is randomised controlled evidence that intravenous ketamine can act as an acute antidepressant with effects that appear to persist long after the drug is considered to have cleared from the body.16,17 I have considered the possibility that the effect seen is due to this small group of patients having become physically dependent on ketamine. On the other hand, patients who abandoned ketamine therapy within the first two years did not report an abstinence syndrome. Anecdotally, over the years, patients who have been on treatment longer than two years occasionally run out of ketamine and sometimes have to wait a few days before having the medication dispensed. To the best of my knowledge, these patients have also not reported an abstinence syndrome, although they do report their pain gets worse. In conclusion, it is unlikely that physical dependence has occurred. The lack of long-term safety data for a drug such as ketamine has been of concern to some authors.6 The limited data I present appears to show that at low doses there does not appear to be any easily observable harm stemming from the use of ketamine. Currently, the total daily dose for most of my patients does not tend to exceed 120 mg per day, with the odd exception. There is evidence to suggest that liver and urinary tract side effects are dose-dependent phenomena.18 This is reassuring – after all, we still use paracetamol for pain relief, even though we know that in overdose, the side effects can be serious. There is also data to suggest that high doses of ketamine may actually cause hyperalgaesia,19 so there are several reasons to not escalate the dose of ketamine. My data suggests that hallucinations are not that common at the dose used. If they do occur, they are not usually too intrusive, although one patient had to decrease her dose to 1 mg three times per day. Higher doses made her very sleepy and even on this lower dose she would experience some visual disturbances (e.g. the ceiling looked like syrup, which would drip to the floor). This patient discontinued her treatment after almost two years after not attending for follow-up. Another elderly patient saw an apparition of her deceased mother standing at the bottom of her hospital bed when 11

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she tried ketamine for the first time. This was clearly unsettling for her because her mother had passed away many years ago. Needless to say, this patient did not progress to taking ketamine on a regular basis. Another regular user of ketamine reported that once, after having taken ketamine on an empty stomach, and subsequently having breakfast, that his breakfast cereal looked like rocks. It is argued that if the beneficial effect of ketamine is a placebo effect, then there is clearly an opportunity cost associated with my activity. On the other hand, if this is a placebo effect, this ‘placebo’ effect has satisfied my patients for a considerable period of time and I have helped my patients to avoid some of the riskier interventions that we pain physicians have at our disposal and that they may not necessarily have wanted to pursue. Unfortunately, there does not appear to be a consistent pattern as to what types of pain ketamine is most helpful for. Some would argue that snake oil appears to have similar breadth of beneficial effect. Some proponents of ketamine prefer the use of an intravenous infusion approach, rather than the sublingual approach. In 2012, Patil and colleagues published a fiveyear retrospective analysis of 49 patients with chronic pain who had undergone a total of 369 outpatient ketamine infusions between them.20 They concluded that ‘in patients with severe refractory pain of multiple aetiologies, subanaesthetic ketamine infusions may improve Visual Analogue Scale scores’. In half of their patients, relief lasted for up to three weeks with minimal side effects. Some advocates of ketamine have gone even further and used substantial doses of ketamine to induce a coma in an attempt to ‘reboot’ the central nervous system, but death is a rare complication of this procedure21 – hence my preference for using the sublingual route at a fraction of these doses. While I hope that the following anecdote will not encourage patients to try this, I would like to report that one of my patients inadvertently took ten times her normal dose – 200 mg rather than 20 mg – while on holiday abroad – this happened because she lost her normal oral syringe and was unfamiliar with the markings and units on the replacement syringe she obtained from the pharmacy where she was abroad. She reports that her family said she was unconscious for 18 hours, but recovered with no ill effect, apart from suffering ‘a bit of a fright’. Following this incident, I stopped prescribing ketamine for this patient because she had previously reported inconsistent benefit and, in any event, she had stopped taking it after this incident. I continue to train and obtain treatment agreements and consent from patients myself prior to commencing them on sublingual ketamine. While I am now sufficiently confident that ward staff could probably be trained to do this, there isn’t enough volume per year to ensure that they would be regularly exposed to carrying out this activity. Furthermore, local circumstances dictate that I can’t always guarantee that the same staff will be available on the ward – so while training the patient and securing the treatment and obtaining informed consent can be time consuming, the benefit is that this expertise stays with me and at least I know I have said the same consistent thing each time. In the NHS setting, the income this activity attracts under the payment-by-results regime is the income that is obtained when the patient is admitted as a day case to try ketamine. Subsequent income is generated from each outpatient attendance. The income generated from the day-case attendance depends on patient comorbidities – some recent trials have earned £221–385 of income for my unit. At the time of data 12

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lockdown, my pharmacy informed me that the cost of supplying ketamine to the 47 patients was about £25 000 per annum. This equates to approximately £530 per patient per annum, or about £44 per month.

Conclusion The long-term use of low-dose sublingual ketamine in chronic pain appears to be safe. Some patients find it very helpful for their pain when other drugs have not worked. To date, using it long term has not appeared to cause too many problems. Acknowledgements

I would like to acknowledge the contribution made by Chronic Pain Clinical Nurse Specialist Susan Downs, who helped to input the BPI data on the PACS after reviewing the patients. Conflict of interest disclosures

Over the years I have attended numerous lunches and dinners paid for by many different drug companies and over the years have also been the recipient of ‘Post-its’, pens, memory sticks, mugs and so on. Under the payment-by-results regime, my Trust will earn money for each patient who attends to try ketamine and who then attends regularly to be monitored and to pick up their ketamine prescription. Disclaimer

While I have made every effort to ensure that there is no misleading data or statement in this paper, and that all drug doses are presented accurately, readers are advised to ensure that drug usage as described in this paper is followed in conjunction with the drug manufacturer’s own literature. I do not accept any liability for any problems that may arise from following the described medication regimen. Note on supplementary files

To read source data please request from the author by emailing: varunj@rocketmail.com.

References 1

Griffiths, D. P. G., Mitchell Noon, J., Campbell, F. A., & Price, C. M. Clinical governance and chronic pain: towards a practical solution. Anaesthesia 2003, 58:243–248. 2 http://www.drugfoundation.org.nz/ketamine (last accessed 8 December 2012). 3 Lim, D. K. Ketamine associated psychedelic effects and dependence. Singapore Med J 2003, 44(1):31–34. 4 Domino, E. F. Taming the ketamine tiger. Anesthesiology September 2010, 113(3):678–684. 5 Hocking, G. & Cousins, M. J. Ketamine in Chronic Pain Management: An Evidence-Based Review. Anesth Analg 2003, 97:1730–1739. 6 Bell, R. F. Ketamine for chronic non-cancer pain. Pain 2009, 141:210–214. 7 Vick, P. G. & Lamer, T. J. Treatment of central post-stroke pain with oral ketamine. Pain 2001, 92(1–2):311–313. 8 Noppers, I. M. et al. Drug-induced liver injury following a repeated course of ketamine treatment for chronic pain in CRPS type 1 patients: A report of 3 cases. Pain 2011, 152(9):2173–2178. 9 Macintyre, P. E., Schug, S. A., Scott, D. A., Visser, E. J. & Walker, S. M. APM:SE Working Group of the Australian and New Zealand College of Anaesthetists and Faculty of Pain Medicine (2010), Acute Pain Management: Scientific Evidence (3rd edn), ANZCA & FPM, Melbourne. 10 McQuay, H. J., Moore, R. A., Eccleston, C., Morley, S. & Williams, A.C. Systematic review of outpatient services for chronic pain control. Health Technol Assess. 1997, 1(6):i–iv; 1–135. 11 Batchelor, G. Ketamine in neuropathic pain. The Pain Society Newsletter 1999, 1(7):19. 12 Cottrrell, et al. Letter. BMJ 2008, 336:973. 13

http://www.wwl.nhs.uk/Library/All_New_PI_Docs/Audio_Leaflets/Pain/Oral_Ketamine/FT2_trial_of_oral_ketamine.pdf (last accessed 8 December 2012). 14 http://www.wwl.nhs.uk/Library/FOI/Requests/2009/Jan_Jun09/0470b.pdf (last accessed 8 December 2012).

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Grocott, M. Systematic audit of peri-operative care in the UK? Bulletin May 2011, 67:17–18. Zarate, C. A. Jr et al. A randomized trial of an N-methyl-D-aspartate antagonist in treatment-resistant major depression. Archives of General Psychiatry August 2006, 63(8):856–864. 17 Diazgranados, N., Ibrahim, L., Brutsche, N. E., et al. A randomized add-on trial of an N-methyl-D-aspartate antagonist in treatment-resistant bipolar depression. Arch Gen Psychiatry 2010, (67):793–802. 18 Quibell, R., Prommer, E., Mihalyo, M., Twycross, R. & Wilcock, A. Journal of Pain and Symptom Management 2011, 41(3):640–649. 19 Hirota, K., Okawa, H., Appadu, B. L., Grandy, D. K., Devi, L. A. & Lambert, D. G. Stereoselective interaction of ketamine with recombinant μ, κ, and δ opioid receptors expressed in Chinese hamster ovary cells. Anesthesiology 1999, 90:174–182. 20 Patil, S. & Anitescu, M. Efficacy of Outpatient Ketamine Infusions in Refractory Chronic Pain Syndromes: A 5-year Retrospective Analysis. Pain Medicine 2012, 13(2):263–269. 21 Harden, R. Ketamine Analgesia: A Call for Better Science. Pain Medicine 2012, 13(2):145–147. 16

Contacts/correspondence Dr V. K. Jaitly, Department of Anaesthesia, Wrightington Wigan and Leigh NHS Foundation Trust, Royal Albert Edward Infirmary, Wigan Lane, Wigan WN1 1NN, UK E-mail: varunj@rocketmail.com

Intellectual property & copyright statement I as the author of this article retain intellectual property right on the content of this paper. I as the authors of this paper assert and retain legal responsibility for this paper. I fully absolve the Editors and Company of JoOPM of any legal responsibility from the publication of my paper on their website. Copyright 2013. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Establishing a pain service in the community Dr Barbara Hoggart Mrs Eve Jenner Dr Patrick Hill

Abstract Birmingham Community Healthcare NHS Trust is delivering a full multidisciplinary back-pain service to a multi-ethnic population. Through changing working practice the service is able to see 2,500 people with pain per year and offers a comprehensive care package, at a competitive cost, in the community. A key achievement is the synchronous approach by all disciplines in true multidisciplinary working, which enables everyone to be offered any or all of a comprehensive range of treatment and support required to manage their pain effectively. Evaluation has indicated that people have a good experience and the service has proved to be effective in improving confidence in coping with long-term pain. Practice points

1. Multidisciplinary teamwork is essential, but requires constant communication, commitment, support and continuous training to work effectively. 2. A high-quality, cost-effective service needs to provide a complete pathway, including assessment, treatment and self-management support to be financially and clinically effective. 3. Adopting a biopsychosocial model throughout the service is essential and processes need to reflect this. 4. Community-based pain services require expertise at consultant level in the key professions to manage the range of clinical and organisational complexity. For example, people presenting with pain in primary care may need to have organic pathology excluded. All staff benefit from internal systems which provide continuous training and support.

Keywords pain management programme, community, primary care

Introduction Research evidence and the resultant policy guidance that has emerged in the last 30 years for pain services in the UK has clearly indicated that the most effective approach for pain services is multidisciplinary working.1,2,3,4 Recent health policy has encouraged the move for such services from traditional settings in specialist secondary-care centres, to the community. The White Paper ‘Our Health, Our Care, Our Say: a new direction for community services’5 included Journal of Observational Pain Medicine – Volume 1, Number 2 (2013) ISSN 2047-0800


recommendations around early intervention, improved access to community-based services, a commitment to address inequalities of care and to move services closer to peoples’ homes. These recommendations were accompanied by an expectation that the relocated services would improve the patient journey, result in cost-savings and achieve similar treatment outcomes. There is also evidence that demonstrate the benefits of early intervention, preventing people with low back pain remaining off sick for long periods and avoiding the detrimental effects associated with long-term sickness absence.6 Reflecting this understanding, over the last ten years health policy in England has increasingly emphasised the need for health and social care services to act proactively in the management of long-term health conditions.7 The Birmingham Community Healthcare NHS Trust community pain service is delivering a full multidisciplinary assessment, at the first point of contact, to a multiethnic community from a variety of social backgrounds. By changing the style of working, the service is able to see 2,500 people with pain a year and offer a full comprehensive care package at a competitive cost. This paper will outline what has been achieved in a community setting in Birmingham, the second-largest city in the UK. Figure 1 The Birmingham community pain service

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The multidisciplinary pain service (MDPS) led by a Consultant in Pain Management, Consultant Clinical Health Psychologist and a Consultant Physiotherapist, provides early assessment to identify the physical, psychological, emotional, social or medical factors relevant to the person’s pain and associated disabilities. The service establishment for the pain service comprises additional sessions from Consultants in Pain Management, a Health Psychologist, Specialist Physiotherapists, Physiotherapy Assistants and is supported by an administrative team. The service aims to intervene in a timely manner, with appropriate advice, reassurance, treatment and self-management training14 to reduce progression to chronicity and to promote the earliest practical return to work or normal activity.

What happens in practice? The service accepts GP referrals of people with musculoskeletal pain of six weeks or more, although symptoms of a much longer duration are not uncommon. At the initial appointment a comprehensive biopsychosocial assessment is undertaken by the multidisciplinary team. The appointment letter aims to minimise anxiety and ensure realistic expectations, by giving clear information about what will happen, explaining that the individual will see professionals from different specialties. On arrival people complete screening questionnaires, to assess disability and psychosocial factors. These currently comprise Oswestry Disability Index,15 STarT Back Musculoskeletal Screening Tool16 and Pain Detect.17 One set of documentation is used by all members of the team throughout the assessment, enabling the clinicians to gradually build a comprehensive picture of the presenting problems.

Case conference and management plans The assessment clinic concludes with a case conference, attended by all members of the team. At the case conference, the decision agreed with the person is confirmed by the team as to whether further investigations (MRI, X-ray, blood tests), interventions or other treatment (e.g. physiotherapy) are required and what appropriate selfmanagement training and support is needed. The small number (<1%) of people diagnosed with serious or sinister pathology receive a rapid referral to appropriate secondary-care consultants. The management plan agreed by the whole clinical team is also forwarded to the GP. In practice, the plan is often constructed and discussed with the person in clinic, as the clinicians are able to share their findings with each other through written summaries in the documentation and handover discussions, as the assessment proceeds. Most people, therefore, leave the clinic with a written plan summarising the actions that will be taken. If the way forward is unclear and requires revision following the case conference, this will be communicated to the person by telephone the following day. The way the clinic is run enables the team to create a biopsychosocial ‘formulation’ of the person’s pain, the relevant related difficulties and the impact on their and their family’s lives, in one visit. People with chronic pain often have the experience of receiving multiple and conflicting diagnoses, but the clinic structure enables the team to provide consistent information about their condition. Internal audit has shown that approximately 85% of people attending require changes to medication, and 12% are offered interventions such as injections (medial branch block, joint injections, epidurals, etc.). They are referred, with their agreement, to their choice of secondary-care provider for the procedure. 17

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Approximately 20% are offered physiotherapy that has a specific musculoskeletal target, half of who will progress on to self-management training. 70% of people with chronic or long-term pain need to engage in some form of training and support to develop their ability to self-manage their pain and associated difficulties. A variety of interventions are provided, which allows tailoring according to need and thus more efficient use of resources. Group-based support includes Pain Management Programmes (PMP), based on the British Pain Society guidelines4 or similarly structured, but less intensive, Active for Life (AfL) programmes, which are delivered in a variety of community and leisure centres. The service provides an annual total of 15 PMPs, in programmes that run continuously throughout the year. As the programmes run on a rolling basis, rather than with ‘closed’ groups, participants can start attending within four weeks of their initial assessment, reducing waiting times and optimising engagement. A psychologist and physiotherapist jointly lead each three-hour session, which provides information, discussion and coaching in exercise, relaxation training, goal-setting and problem-solving. Participants are expected to attend for a minimum of ten weeks, providing a minimum contact time of 30 hours, but this can be extended if necessary and people can easily attend for ‘booster’ sessions, as required, by rejoining the programme at any later stage. The PMPs are run with groups of 15–20 participants and staffed accordingly. Contrary to traditional group work where 8–10 is seen as the ideal group size,18 because of the diverse population served, we have found that the larger group sizes improve rather than reduce attendance. We feel that this is because it enhances psychosocial processes such as ‘normalising’ and ‘social comparison’, which are known to play a part in people’s adjustment and acceptance of chronic pain.19 There are also 30 AfL programmes, run annually, led by physiotherapists. These shorter, discrete programmes run for one two-hour session per week, for eight weeks, for individuals who are less disabled by their pain. The information content is similar, but there is a greater focus on exercise and resumption of leisure and sporting activity. To address the ethnic diversity of our population, interpreted PMPs and AfL courses are provided. These are run as discrete, single-sex groups and present a range of challenges to the team; however, initial feedback would suggest that they are engaging and effective. The most effective form of support for self-management is the group-based programmes4; however, this is not appropriate for everyone with chronic pain. We thus make use of a range of nationally available self-management support tools that the team has helped to develop, including ‘The Pain Toolkit’20 and an accompanying multi-language DVD; a new supported self-help manual entitled ‘The Pain Plan’21 modelled on the successful ‘Heart Manual’22; and a range of relaxation training materials in different languages. People who require self-management training and support, but who are unable or not ready to attend the group programmes, may be offered appointments in an innovative cognitive-behavioural approach23 taken in this service; the joint psychology and physiotherapy clinic, where they will see both specialities in a single appointment, spending half an hour with each clinician. In this, the (cognitive) barriers to self-management are addressed by the psychologist in conjunction with an immediate (behavioural) coaching session from the physiotherapist. This normalises the psychological input of the service and preserves the integrity of the multifactor, biopsychosocial model which underpins it. This is important for everyone involved, including the staff, in order to reduce the risks of fragmenting the problem, 18

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pathologising the normal psychology of pain24 and silo working, with the inevitable reduction in quality of care and increased dependence on NHS services. A computerised Patient Administration System (PAS) is used to track people through the service and a single set of documentation ensures that the details of their experience are available at all times. The clinician in charge of each stage has responsibility for discharge.

To maintain the standards The service trains all staff in the concepts of pain management. In addition to continuous on-the-job coaching, a quarterly ‘action learning set’ is maintained to help solve problems that may arise in group work and improve their confidence in the delivery of self-management support. Extended Scope Physiotherapists (ESPs) attend the assessment clinic on six-month rotation, which ensures the pool of skilled community physiotherapists becomes ever wider. A questionnaire-based evaluation of this training strategy at the end of 2010 showed that 100% of participants found the training useful, and the training and support has increased knowledge and techniques for both group and one-to-one work.25

Outcomes Audit of patient experience Everyone is given an anonymous questionnaire to complete at home after their visit, to report their experiences of the service and the resulting data is used for service improvement. Analysis of reported experience in 2010 showed 80% satisfaction ratings had been achieved in all aspects of the initial clinic appointment, except for ‘information’.26 To complete the audit cycle, new information leaflets have been designed and printed and a re-audit took place in 2011.

Evaluation In 2010, approval was given to approach 400 people who were discharged from the community pain service over a consecutive three-month period. They were contacted by letter, asking them to take part in a review. Those who consented underwent a semi-structured telephone interview with an independent evaluator (supported by an interpreter where required) and were asked about the impact of the service on their pain and associated difficulties. 78 people were interviewed, including non-English speakers – an ethnic mix that was representative of the local population. The sample also contained a range of people who had experienced all the different interventions delivered by the service. 15 people (20%) had been seen previously in pain clinics in secondary care. Over half said that their quality of life (51%), their ability to cope with their pain (56%) and their confidence in self-managing their pain (55%) was better. One-third of the sample stated that their general abilities (including walking, standing and sitting tolerances) and ability to undertake activities of daily living had improved, as had their mood and general confidence. Approximately half the sample (48%) rated the service alongside their best experience of all NHS services, whereas only 4% said it compared to the worst. This last question sought to identify people who would ‘promote’ the service to those around them by giving positive feedback (48%) and those who would ‘detract’ from the service by giving a negative report to family and friends of their experiences (4%).27 19

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There were no significant differences (p < 0.05) in the reported outcomes from patients previously seen in secondary care.

Productivity In our experience, the service is comparable to established secondary-care services; however, the unit cost per new encounter is below tariff. Further cost-savings are achieved by the design of the service. The presence of the service in the community has provided a shorter journey: a local audit (2008) of people attending a secondary-care pain clinic in Birmingham revealed that 48% of people referred to the clinic had been previously seen in an orthopaedics or rheumatology outpatient clinic. On average, people had attended 2.3 outpatient appointments with little measurable benefit. This circuitous journey resulted in an average of 87 weeks from onset of problem to presentation at a pain clinic.28 In our view, this shorter journey has reduced the risk of iatrogenic harm and, through avoiding unnecessary outpatient appointments, a substantial reduction in cost to the NHS. The care-planning that takes place and is finalised in the post-assessment clinic case conference results in a substantial decrease in medical follow-up requirements (1 new to 0.6 follow-up has been maintained for five years). This maintained ratio is unique in the delivery of pain services, as far as we are aware. The service has consultant medical staff who have the specialist knowledge which results in few people (4%) being referred into secondary care for a further specialist opinion (neurosurgery, rheumatology or orthopaedics). The reported prevalence of back pain due to facet joint problems varies from 15 to 40%. However, confirmation that facet joint problems are the cause of the presenting back pain is challenging and the appropriate timing of injections as a treatment is yet to be fully determined. In our clinic we, as a team, agree that the facet joint is important and requires injection intervention in approximately 12% of the patients. Conversion figures for injection interventions are not published nationally, but we accept this is at the low end of the spectrum. Other pain services which do not offer a â&#x20AC;&#x2DC;one stopâ&#x20AC;&#x2122; assessment by all specialties often refer internally, extending the timeline of the care pathway, which can result in inefficient working and high non-attendance rates.

Conclusion and future perspective The community pain service has been successfully established and has met its stated objectives across north and east Birmingham, that is to establish a pain service in the community that is comparable to established secondary-care services, cost-effective, with good outcomes and a positive image within the diverse community that it serves. The team aims to expand the approach to provide access for everyone with chronic pain across the city of Birmingham over the next five years. Multidisciplinary working is something many services purport to do, but in reality different professional groups often continue to work in silos, fragmenting the care pathway and reducing the impact of the service on patient care. The key achievement of the clinic is the synchronous approach by all disciplines, which allows everyone to be offered any or all of the treatments and support required to manage their pain effectively. The different professional groups involved in this service have learned the value of true team-working, which demands meaningful interaction, sharing and development of skills, clear communication, joint care-planning and case discussion with team reviews as necessary. 20

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Evaluation of the service has demonstrated that those who participated had a good experience. Furthermore, the service has proved to be effective in terms of improving confidence in coping for the majority of people with long-term pain. The team which has developed this approach is now keen to share its learning from the last four years and to make service commissioners and providers aware of the potential of this form of community-based pain service. We feel that the summary outlined in this paper shows promise and a way forward for the next phase of development of pain services in the UK over the next ten years.

References 1. Eccleston. C., Williams, A. C. de C., & Morley, S. Psychological therapies for the management of chronic pain (excluding headache) in adults. Cochrane Database of Systematic Reviews 2009, Issue 4 Art. 2. Flor, H., Fydrich, T., & Turk, D. C. Efficacy of multidisciplinary pain treatment centers: a meta-analytic review. Pain 1992, 49:221–230. 3. Morley, S., Eccleston, C., Williams, A. Systematic review and meta-analysis of randomized controlled trials of cognitive behaviour therapy for chronic pain adults, excluding headache. Pain 1999, 80:1–13. *4. The British Pain Society. Recommended Guidelines for Pain Management Programmes for Adults 2007. Clear guidance for what is required to deliver an effective pain self-management support programme. 5. Department of Health: ‘Our health, our care, our say’ White Paper. ISBN 0101673728 (London: Department of Health, 2006). 6. Waddell, G. & Burton, K. M. Concepts of rehabilitation for the management of low back pain. Best Practice & Research Clinical Rheumatology 2005, 19(4):655–670. 7. Wanless, D: Securing our Future Health: Taking a Long-term View (London: H. M. Treasury, 2002). 8. Maniadakis, N. & Gray, A. The economic burden of back pain in the UK. Pain 2000, 84:95–103. 9. Krismer, M. & van Tulder, M. Low back pain (non-specific). Best Practice & Research Clinical Rheumatology 2007, 21(1):77–91. 10. Foster, N. E., Pincus, T., Underwood, M. R., Vogel, S., Breen, A., & Harding, G. Understanding the process of care for musculoskeletal conditions – why a biomedical approach is inadequate. Rheumatology 2003, 42:401–403. 11. Watson, P. J. & Main, C. J. Influence of benefit type on presenting characteristics and outcome from an occupationally orientated rehabilitation programme for unemployed people with chronic low back pain. Physiotherapy 2004, 90:4–11. 12. Watson, P. From back pain to work: A collaborative initiative between the National Disability Development initiative and the Department of Behavioural Medicine Salford Royal Hospitals Trust. Physiotherapy Pain Association News 2001, 12:28–29. 13. Niv, D. & Devor, M. Position paper of the European Federation of IASP Chapters (EFIC) on the subject of pain management. European Journal of Pain 2007, 11:487–489. 14. Breen, A., Austin, H., Campion-Smith, C., Carr, E., & Mann, E. ‘You feel so hopeless’. A qualitative study of GP management of acute back pain. European Journal of Pain 2007, 11:21–29. 15. Fairbank, J. Oswestry Disability Index (ODI). Spine 1995, 20(13):1535–1537. **16. Hill, J. C., Whitehurst, D. G. T., & Lewis, M. et al. Comparison of stratified primary care management for low back pain with current best practice (STarT Back): a randomised control trial. The Lancet 2011, 378(9802):1560–1571. This paper demonstrates the possibilities of improved primary-care services for low back pain through the use of this simple stratification tool. 17. Freynhagen, R., Strojek, K., Griesing, T., Whalen, E., & Balkenohl, M. Efficacy of pregabalin in neuropathic pain, evaluated in a 12-week, randomised, double-blind, multicentre, placebo-controlled trial of flexible- and fixed-dose regimens. Pain 2005, 115(3):254–263. 18. Yalom, I. The Theory and Practice of Group Psychotherapy 2005 (5th edn). 19. Skevington, S. M. Social comparisons in cross-cultural quality of life assessment. Int J Mental Health 1994, 2:29–47. 20. Moore, P. & Cole, F. The Pain Toolkit. Department of Health (2008). 21. Cole, F., Hill, P., Jenner, E., Ashworth, P., Lewin, R. J. ‘The Pain Management Plan: The development and pilot study of a home-based cognitive-behavioural approach supporting the selfmanagement of chronic pain’ (poster). British Pain Society Annual Scientific Meeting, Edinburgh (2011).

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*22. Lewin, B., Robertson, I. H., & Cay, E. L. et al. A self-help post-MI rehabilitation package – the Heart Manual: effects on psychological adjustment, hospitalisation and GP consultation. The Lancet 1992, 339:1036–1040. Reports the evidence for the effectiveness of a home-based self-management support intervention. 23. Turk, D. C. & Gatchel, R. J. (eds.) Psychological Approaches to Pain Management, 2nd edn (New York: Guilford Press, 2002). **24. Eccleston, C. A normal Psychology of Pain. The Psychologist 2011, 24(6):422–426. Professor Eccleston contrasts the normal psychology of chronic pain with the traditional abnormal psychology approach and explains how adopting a ‘normal psychology of pain’ enables a focus on the actions that people can take to regain control over their lives. 25. Rex, Z., Hill, P., & Jenner, E. ‘Establishing Pain Services in the Community: A training approach’ (poster). British Pain Society Pain Management Programmes Special Interest Group Biannual Conference, Bath (2011). 26. Jenner, E., Chipchase, L., Hill, P., & Hoggart, B. ‘An Audit of Perceived Healthcare Quality in a Primary Care Pain Clinic’ (poster). British Pain Society Annual Scientific Meeting, Edinburgh (2011). 27. Hoggart, B., Hill, P., Chipchase, L., Jenner, E., & Shalaby, M. ‘Evaluation of a Primary Care Multidisciplinary Pain Service’ (poster). British Pain Society Annual Scientific Meeting, Edinburgh (2011). 28. Wallis, T., Fenlon, J., & Hoggart, B. ‘The changing referral pattern of patients to a Pain Clinic 2000– 2007’ (poster). British Pain Society Annual Scientific Meeting, Liverpool (2008).

Contacts / correspondence Dr Barbara Hoggart, Birmingham Community Healthcare NHS Trust, The Dove Primary Care Centre, Dovedale Rd., Birmingham B23 5BG Tel: 0121 465 5693 Fax: 0121 465 5700 E-mail: barbara.hoggart@heartofengland.nhs.uk

Intellectual property & copyright statement We as the authors of this article retain intellectual property right on the content of this paper. We as the authors of this paper assert and retain legal responsibility for this paper. We fully absolve the Editors and Company of JoOPM of any legal responsibility from the publication of our paper on their website. Copyright 2013. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Pain perception in altered states of consciousness Laura Munglani

1

Definitions1: Coma – a state of total lack of arousal and behavioural unresponsiveness (i.e. a lack of consciousness). Vegetative state (VS) – a state of responsiveness and wakefulness (periods of preserved behavioural arousal) without conscious awareness of self and environment. Patients present no language production or comprehension. Minimally conscious state (MCS) – patients show reproducible but minimal and fluctuating signs of consciousness but are unable to communicate effectively. With improvements in intensive care, many patients survive severe brain injury but remain with deficits of consciousness and information processing. At any one time it is estimated that 1,000 patients are kept alive in the UK in the hope that they may one day regain consciousness.2 These patients may awaken from their coma but still show no signs of awareness; and are often described as being in a vegetative state (VS), or a minimally conscious state (MCS). To what extent are these patients able to feel pain? Currently there is little research and almost evenly divided medical opinions, with 56% thinking these patients can feel pain.3 Nociception is a physiological response to a noxious or adverse stimulation. In contrast, pain is the product of a complex interaction between unpleasant stimuli and the central nervous system, and involves conscious experience. Suffering, in a broad sense, is an individual’s basic affective experience of unpleasantness and aversion associated with harm or threat of harm.4 Using functional magnetic resonance imaging (fMRI), a distinction may be made between brain areas involved in pain perception and those involved in suffering; the latter as a complex cognitive affective phenomenon often integrated with subcortical areas associated with prior exposure and meaning. The question of whether such patients suffer or not will have a profound effect on how they are treated and how they are allowed to die. Therefore, it is crucial to examine whether those patients diagnosed as being in a VS or an MCS are ‘conscious’. The definition of VS precludes being conscious, while MCS patients are thought to have fluctuating episodes of consciousness. However, these behavioural scales are not standardised and it is suggested that the misdiagnosis rate is 40%.5 It is worth noting that VS and MCS are behavioural descriptors, and are not patho1

Fourth-year medical student, Balliol College, the University of Oxford. A shorter version of this article has been published in the Oxford Medical School Gazette. Journal of Observational Pain Medicine – Volume 1, Number 2 (2013) ISSN 2047-0800


physiologically defined. Studies have shown important differences in brain function and possible consciousness between the two populations using positron emission tomography (PET) scans.6,7 Owen’s team used fMRI and found that a woman in a VS seemed to be conscious.8 fMRI investigates the real time activity of the brain by measuring the blood-oxygenlevel-dependent (BOLD) response within different areas of the brain. Subjects were asked to imagine playing tennis or walking around their home. These scenarios were chosen because the brain areas involved are characteristic and spatially distinct, and in healthy volunteers the two tasks use motor and spatial imagery respectively. This allows real-time interpretation of the activity pattern on an individual patient basis. Owen’s team asked a series of patients with disorders of consciousness ‘yes’ or ‘no’ questions, a minority of which were then able to answer by imagining one of the two activities. In 2010, Owen’s team also reported a 24-year-old male who was classified as being in a VS following a road traffic accident fiver years previously but using a selective mental imagery paradigm was able to correctly answer 5 out of 6 verifiable questions.9 This landmark study showed it was possible to exchange information with someone in a VS and the team inferred that he was aware, and that many other higher cognitive functions were largely intact. However, there is much debate on the matter. Many critics argue that fMRI is only an indirect measure of consciousness. Still little is known about what it is like to be in either a VS or MCS, and fMRI can provide a useful tool for communicating with these patients. If Owen’s estimate that 1 in 5 people in a VS are indeed ‘conscious’ and able to communicate using brain activity9 is right, then this raises the possibility that such patients may feel pain. Indeed, VS patients are able to demonstrate responses such as grimaces, tachycardia and posturing, causing some to suggest that they are perceiving pain.5 Studies suggest that awareness of pain is thought to occur at the cortical level while the nociceptive responses, grimacing and crying, are subcortically mediated. Studies done during general anaesthesia indicate that motor responses or autonomic signs (e.g. respiratory frequency, heart rate, blood pressure) are not reliable measures of the conscious perception of pain.10 Though the precise cortical and related subcortical nuclei of the conscious perception of pain aren’t defined, a lateral and a medial pain system have been described. The lateral system includes the lateral thalamus, primary and secondary somatosensory cortex, parietal operculum and insula. The medial pain system involves the medial thalamus, anterior cingulate, amygdala, hippocampus, hypothalamus, locus coeruleus and periaqueductal grey matter. One study using PET to measure brain activation to noxious electrical stimulation of the median nerve supported the conclusion that patients in MCS have neural systems required to experience or at least to allow for awareness of nociceptive stimuli but that patients in VS might not.6 In VS patients, painful stimuli may not reach the threshold to become consciously experienced, even if there was some cortical processing.5 The question arises whether MCS or VS patients, even if they consciously perceive pain, are likely to have the same sort of experience of the pain and suffering as experienced by otherwise fully conscious individuals. In November 2012, Owen, using fMRI, asked 39-year-old VS patient Scott Routley if he was in pain at that moment in time. Through selective mental imagery Routley answered ‘no’.11 24

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To our knowledge, Routley is the only disorder of consciousness patient so far to have been asked whether he is in pain, in a situation where the means were too hard to detect a response. Though it must come as a great relief to the medical community that he was not in pain at the moment the question was asked, to our best estimation there is likely to be enormous heterogeneity in the patient group. In particular, the varying types of injury that lead to coma, VS and MCS make it likely that there will be differences in the brain activity, preventing generalisations to be made. Medical staff have an ethical obligation to provide empathetic and compassionate care to all patients, through the principles of beneficence – doing what is best for the patient – and nonmaleficiance – doing no harm, even if those patients cannot report their pain.12 The most recent evidence, with the exception of Routley, suggests that a cautious approach needs to be taken if, indeed, patients have the potential to feel pain and suffer, with fMRI being used to direct analgesia use. However, it is important to note that Routley may not have been in a state that would have been expected to elicit pain in a conscious person at the time he was asked. Therefore, the fact that he said ‘no’ may reflect his situation at the time, rather than an inability to feel pain. However, with end-of-life care a more ethically demanding scenario arises. Currently, the law allows VS patients to have active feeding and fluid therapy withdrawn to allow them to die, thereby literally dehydrating to death. In addition, the current standards do not call for opioids to be given.13 The recent fMRI studies suggest such withdrawal of active feeding and hydration may lead to intense suffering.14 At present there is not enough evidence into the experience of patients who undergo withdrawal of artificial nutrition and hydration. Dehydration and the refusal of food may be a natural part of the dying process, for example in terminally ill patients. They are generally not thought to suffer15 and any feeling of thirst can be alleviated through good nursing care, such as keeping the lips, nose and eyes moist.16 However, the General Medical Council (GMC) guidelines on ‘Treatment and care towards the end of life’ states: ‘[there may be] concerns that patients who are unconscious or semi-conscious may be experiencing distressing symptoms and complications, or otherwise be suffering because their needs for nutrition and hydration are not being met’.17 In Bland’s case in 1993, relatives won the right to withdraw treatment to allow him to die – a so-called ‘mercy killing’.18 However, Bland was thought to be in the extreme form of VS – one judge in the case stated that Bland was just a ‘shell’. fMRI may be able to help distinguish the level of consciousness, and therefore capacity to experience pain and suffering in those patients who can’t be distinguished reliably behaviourally between at the bedside. Though fMRI has been able to show that some patients in VS and MCS are conscious, it requires that the patients be put into the scanner, which may be impossible if the patient has any metal implants. Problems of accessibility and expenses prevent this technique being used more widely, especially as the conscious state of the patient changes there is a need to recheck the patients, making the cost quite substantial. There is a need to develop a bedside method of awareness detection that does not rely on behavioural responses.

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In 2011, Owen’s team published a paper on the bedside detection of awareness using an electroencephalography (EEG) technique, assessing 16 patients diagnosed in a VS.19 Though an EEG lacks fMRI’s precision and cannot look as deeply into the brain, the team found that three of the patients were able to repeatedly and reliably generate appropriate EEG responses to two distinct commands, even though they were behaviourally unresponsive. As the EEG is highly portable, inexpensive, a bedside test, available in most hospitals and can be used on patients who have metal implants, this could allow the awareness of every patient with a disorder of consciousness to be assessed. However, earlier this year another group reanalysed Owen’s data and concluded that the method was flawed.20 Goldfine suggested that the brain activity patterns exhibited by the three patients were contaminated by electrical signals caused by muscle movements unrelated to the imagined tasks. It can be seen, therefore, that there is much debate on the use of EEG; however, the fMRI studies are less contentious. More work needs to be done to validate the methods used and find a reliable bedside test that could be widely used. In conclusion, the detection of pain perception in VS and MCS patients remains a challenging but crucial task in the management of patients recovering from coma, where behavioural responses to nociception cannot be accurately assessed. It may never be possible to be totally sure to what degree, if any, they may suffer. Though new scales to assess nociception response are being developed,21 it seems that fMRI may provide a window into the world of such patients and by communicating with patients and asking them if they feel pain, allows steps to be taken to improve their quality of life.

References 1

Monti, M., & Laureys, S. Clinical review: the vegetative state. BMJ 2010, 341:c3765. Alleyne, R., & Beckford, M. Patients in ‘vegetative’ state can think and communicate. The Telegraph. 3 February 2010. Available at http://www.telegraph.co.uk/health/healthnews/7150119/Patients-in-vegetative-state-can-think-andcommunicate.html [accessed 2 February 2013]. 3 Demertzi, A., Schnakers, C., & Ledoux, D. et al. Different beliefs about pain perception in the vegetative and minimally conscious states: a European survey of medical and paramedical professionals. Prog Brain Res 2009, 177:329–338. 4 Suffering. Available at http://en.wikipedia.org/wiki/Suffering [accessed 27 January 2013]. 5 Schnakers, C., & Zasler, N. D. Pain assessment and management in disorders of consciousness. Curr Opin Neurol 2007, 20:620–626. 6 Boly, M., Faymonville, M. E., & Schnakers, C. et al. Perception of pain in the minimally conscious state with PET activation: an observational study. Lancet Neurol 2008, 7:1013–1020. 7 Owen, A. M., Menon, D. K., & Johnsrude, I. S. et al. Detecting residual cognitive function in persistent vegetative state. Neurocase 2002, 8:8394–8403. 8 Owen, A. M., Coleman, M. R., & Davis, M. H., et al. Detecting awareness in the vegetative state. Science 2006, 313:1402. 9 Monti, M. M., Vanhaudenhuyse, A., Coleman, M. R., Boly, M., Pickard, J. D., Tshibanda, L., Owen, A. M., & Laureys, S. Willful modulation of brain activity in disorders of consciousness. N Engl J Med 2010, 362(7):579–589. 10 Halliburton, J. R. Awareness during general anesthesia: new technology for an old problem. CRNA 1998, 9:39–43. 11 Walsh, F. Vegetative patient Scott Routley says ‘I’m not in pain’. Available at http://www.bbc.co.uk/news/health20268044 [accessed 9 January 2013]. 12 Herr, K., Coyne, P. J., & Key, T. et al. Pain assessment in the nonverbal patient: position statement with clinical practice recommendations. Pain Manage Nurs 2006, 7:44–52. 13 Wijdicks, E. F. Minimally conscious state vs. persistent vegetative state: the case of Terry (Wallis) vs. the case of Terri (Schiavo). Mayo Clin Proc 2006, 81:1155–1158. 14 Smith, W. J. A ‘painless’ death? Available at http://www.catholiceducation.org/articles/medical_ethics/me0074.html [accessed 2 February 2013]. 15 Ganzini, L., Goy, E. R., Miller, L. L., Harvath, T. A., Jackson, A., Delorit, M. A. Nurses’ experiences with hospice patients who refuse food and fluids to hasten death. N Engl J Med 24 July 2003, 349(4):359–365. 2

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16

Slomka, J. Withholding nutrition at the end of life: clinical and ethical issues. Cleveland Clinic Journal of Medicine 2003, 70(6):548–552. 17 GMC Guidelines. Treatment and care towards the end of life: good practice in decision making. 20 May 2010. 18 Airedale NHS Trust v. Bland (1993) AC 789 HL. 19 Cruse, D., Chennu, S., Chatelle, C., Bekinschtein, T. A., Fernández-Espejo, D., Pickard, J. D., Laureys ,S., & Owen, A. M. Bedside detection of awareness in the vegetative state: a cohort study. The Lancet 2011, 378(9809):2088–2094. 20 Goldfine, A., Bardin, J., Noirhomme, Q., Fins, J., Schiff, N., & Victor, J. Reanalysis of ‘Bedside detection of awareness in the vegetative state: a cohort study’ The Lancet 2013, 381(9863):289–291. 21 Schnakers, C. et al. The nociception coma scale: a new tool to assess nociception in disorders of consciousness. Pain 2010, 148:215–219.

Contacts/correspondence Laura Munglani, email : laura.munglani@balliol.ox.ac.uk

Intellectual property & copyright statement We as the authors of this article retain intellectual property right on the content of this paper. We as the authors of this paper assert and retain legal responsibility for this paper. We fully absolve the Editors and Company of JoOPM of any legal responsibility from the publication of our paper on their website. Copyright 2013. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Communication with pain in mind M.D. Spencer

1

Commentary on: Munglani, L. ‘Pain perception in altered states of consciousness’. Journal of Observational Pain Medicine 2, 2013.

The question as to whether patients in the vegetative state can feel pain is difficult and unanswered. Writing in this issue, Munglani (2013) presents a thoughtprovoking review of recent literature that demonstrates the ability to communicate, in certain cases, with patients who had been diagnosed to be in a vegetative state, through the use of neuroimaging techniques of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). She suggests that the ability to communicate (e.g. by using the distinct responses of thinking about either playing tennis or walking around their home as a means of responding to ‘yes’/’no’ questions) raises the possibility that such patients may also possess intact means to perceive pain and hence experience suffering. While is it reassuring that, in the case reports she cited, patients were not in pain, Munglani also draws our attention to the practice of the withdrawal of active feeding and fluid therapy from patients in the vegetative state, and poses the question as to whether enough is being done to ascertain, in such patients, whether pain associated with the withdrawal of nutrition and hydration is adequately controlled. She suggests that neurosurgical paradigms, while requiring further refinement to translate them from the realm of research studies requiring cumbersome and expensive scanning facilities to the bedside in the ward or the intensive care unit, could offer a means to communicate with otherwise unreachable patients to ask the most fundamental and humane question: ‘Are you in pain?’ The questions that Munglani poses will provoke questions as to our practice in a range of clinical scenarios involving the minimally conscious. Once our ability to communicate with at least a subgroup of patients currently diagnosed as in a vegetative state becomes established, how will this new ability to communicate become integrated with our practices as regards to consent and advance directives? The code of practice for the Mental Capacity Act 2005 (England and Wales) sets out a consideration of an individual’s ability to communicate their decisions as part of the framework for assessing capacity, and states: ‘If a person cannot communicate their decision in any way at all, the Act says they should be treated as if they are unable to make that decision.‘ However, ‘Before deciding that someone falls into this category, it is important to make all practical and appropriate efforts to help them communicate.’ It would follow that if future advances in neuroimaging can extend the ability of vegetative-state patients to communicate, this may, in certain cases, restore capacity to patients. Our clinical practices may then require modification to provide patients with the means to confirm or withdraw their previously given consent prior to end1

Autism Research Centre, University of Cambridge Journal of Observational Pain Medicine – Volume 1, Number 2 (2013) ISSN 2047-0800


of-life procedures – and, thus, to be afforded the same opportunities to withdraw consent as are routinely given to conscious patients right up until the last moment before operations for which they have previously been consented. Munglani’s article suggests that while practical bedside tests are not yet available, neuroimaging case studies would appear to provide ‘proof of principle’. Timely debate about the ethical and legal issues raised would appear to be indicated.

References Munglani, L. ‘Pain perception in altered states of consciousness’. Journal of Observational Pain Medicine 2, 2013. Department for Constitutional Affairs. Mental Capacity Act 2005: Code of Practice (The Stationery Office: London, 2007).

Contacts / correspondence Dr Michael Spencer: spencer@mdspencer.com

Intellectual property & copyright statement We as the authors of this article retain intellectual property right on the content of this paper. We as the authors of this paper assert and retain legal responsibility for this paper. We fully absolve the Editors and Company of JoOPM of any legal responsibility from the publication of our paper on their website. Copyright 2013. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Looking for idiopathic intracranial hypertension in patients with chronic fatigue syndrome 1

2

Dr Nicholas Higgins FRCP FRCR, Prof. John Pickard F Med Sci, Prof. Andrew Lever F Med 3 Sci

Abstract Introduction: Headache is common in chronic fatigue syndrome, a condition of unknown cause in which there are no clinical signs. Fatigue is common in idiopathic intracranial hypertension, a headache condition of unknown cause in which the only clinical signs are those of raised intracranial pressure, signs which may be absent. Might, therefore, idiopathic intracranial hypertension be present in some patients diagnosed with chronic fatigue syndrome? Could the two conditions be related? Patients and methods: From June 2007, patients attending a specialist clinic who fulfilled the diagnostic criteria for chronic fatigue syndrome and in whom headache was an especially prominent symptom were offered CT venography and lumbar puncture, looking for evidence of raised intracranial pressure. Results: Of the 20 patients who accepted lumbar puncture, eight had pressures of 20 cm H2O or greater, including three who had pressures of 25 cm H2O or greater. Mean pressure was 19 cm H2O. Conclusions: Some patients with headache and a diagnosis of chronic fatigue syndrome have unrecognised and occult idiopathic intracranial hypertension. The possibility that the two conditions are related cannot be excluded. Keywords Chronic fatigue syndrome, idiopathic intracranial hypertension, headache, lumbar puncture

1

Consultant Neuroradiologist, Addenbrooke’s Hospital, Cambridge CB2 0QQ. Professor of Infectious Diseases, Addenbrooke’s Hospital, Cambridge CB2 0QQ. 3 Professor of Neurosurgery, Addenbrooke’s Hospital, Cambridge CB2 0QQ. 2

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Introduction Chronic fatigue syndrome (CFS) is a condition of unknown aetiology, characterised by debilitating fatigue and defined by a constellation of symptoms without any accompanying physical signs. It can develop at almost any age and symptoms can last for many years. Treatment is largely supportive. Headache is a common complaint.1,2,3 Idiopathic intracranial hypertension (IIH) is a condition characterised by headache and visual disturbance, and it is defined by the presence of raised intracranial pressure but without any discernable cause. It affects mainly young obese women but can develop in either sex, at almost any age, and symptoms can last for many years. Treatment is palliative and largely directed at preserving sight. Though not exciting much comment (because headache and visual symptoms are so consuming), fatigue is a common symptom.4,5,6,7 The clinical features of IIH, of which headache and papilloedema are the most common, reflect the abnormal intracranial pressure but are otherwise completely non-specific. Moreover, some patients with IIH may have headache without signs of raised intracranial pressure and these patients can be difficult to diagnose, especially if they do not conform to the usual IIH phenotype of the young, obese female.6,8 In order not to miss these cases, therefore, we extended the diagnostic work-up of patients with chronic fatigue to specifically exclude raised intracranial pressure when headache was a prominent symptom.

Patients and methods From June 2007 to March 2012, 25 patients attending a specialist clinic, who satisfied the accepted criteria for CFS,1 in whom headache was a prominent symptom, were referred for brain CT and CT venography with a view to lumbar puncture. All patients had had symptoms for at least six months. None had papilloedema or any other sign of raised intracranial pressure. A standard brain CT scan was used to screen for hydrocephalus or intracranial mass. Cerebral CT venography (CTV) was performed at the same time, first, to exclude venous sinus thrombosis and, second, to look for narrowing of the transverse sinuses (now widely recognised as an indicator of raised intracranial pressure).9,10,11 If the imaging suggested no contraindication, then patients were offered lumbar puncture; this procedure carried out subsequently in the left lateral position using a 22 gauge needle with pressures referenced to zero at the point of needle insertion.

Results 25 patients were referred in total. Standard brain CT was normal in all cases. CTV showed no evidence of existing or previous thrombosis in any case. Bilateral focal narrowing of the transverse sinuses was seen in two cases (one subsequently diagnosed with IIH). 20 patients accepted the offer of a lumbar puncture and five refused. Of the 20 who accepted, eight had intracranial pressures of 20 cm H2O or greater, including three with pressures of 25 cm H2O or greater. Mean pressure in the group was 19 cm H2O.

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The three patients with pressures of 25 cm H2O or greater were relabelled as IIH. Of these, two were obese and the other was moderately overweight (see Table 1).

Table 1 – Characteristics of 20 patients diagnosed with CFS who had lumbar puncture

CSF pressure (cm water)

BMI (kg/m2)

BTSS (on CTV)

Sex

Age

41 29 25 22 21 20 20 20 19 19 17 17 17 15 15 14 14 12 12 12

36 31 27 22 39 27 30 36 31 23 18 30 31 23 26 20 21 23 27 22

yes no no no no no no yes no no no no no no no no no no no no

f m m m f f m f f f f f m m m f f f f f

40 53 60 21 46 22 39 49 26 16 20 22 18 62 47 23 27 47 22 41

Length of history (years) 1.5 6 10 3 2.5 5 5 11 13 0.5 0.8 8 0.8 15 0.5 12 9 30 3 12

BMI: body mass index (normal, 18.5–25; overweight, 25–30; obese > 30) BTSS: bilateral transverse sinus stenoses CSF: cerebrospinal fluid

Discussion Headache in IIH is generally non-specific. Moreover, IIH can exist without papilloedema or other signs of raised intracranial pressure, meaning, especially in the absence of the usual phenotype, it is easily overlooked as a cause of headache.8,12,13,14,15 Mathew and co-workers, for example, used lumbar puncture to screen for IIH without papilloedema in patients with a transformed migraine type of chronic daily headache and found a prevalence of 14% in 85 patients.12 Since then, the presence of stenoses in both transverse venous sinuses has come to be recognised as a marker of raised intracranial pressure, a sign which can be detected non invasively.9,10,11 Bono et al. screened 724 patients attending an outpatient clinic with migraine for raised intracranial pressure using cerebral MR venography (MRV).14 Patients who had bilateral transverse sinus stenoses on MRV were offered

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lumbar puncture. They found 7% of patients were positive on MRV. Of those who went on to have a lumbar puncture, 70% had raised intracranial pressure; this implying, as a minimum, that 5% of their patients diagnosed with migraine actually had IIH. The same group, using the same method, published almost identical findings in patients with chronic tension headache.15 None of the patients in either study had papilloedema and, apart from a shorter history and a tendency to greater obesity, there was nothing to distinguish patients with IIH from the other patients with headache. MRV is a useful non-invasive tool for diagnosing raised intracranial pressure but has limited sensitivity. Higgins et al., using a similar protocol to Bono et al. showed previously that bilateral transverse sinus stenoses might be seen in 65% of patients with proven IIH.10 Other patients with IIH had less striking venous anomalies or none. Relying on this sign to screen for raised intracranial pressure, therefore, will mean underestimating the number of cases. So, the true prevalence of IIH in patients with migraine, for example, is not likely to be less than 8% and could be nearer the 14% reported by Mathew and colleagues.12 If patients with unrecognised IIH comprise a significant proportion of patients attending headache clinics, then they probably also form a significant proportion of other patient populations where chronic headache is a feature, including patients with chronic fatigue. So, with a question over the accuracy of imaging techniques in excluding it, we opted for lumbar puncture as the gold standard measurement of intracranial pressure and used CT and CTV primarily to screen for contraindications to lumbar puncture and to exclude alternative diagnoses. Our results, in which 3 patients out of 20 were found to have raised intracranial pressure, would seem to justify this approach. Interestingly, five additional patients in our series had CSF pressures that were borderline high, if not actually abnormal by the most stringent criteria. Two of these were obese, three were moderately overweight and all would likely have been labelled as IIH if they had had papilloedema. Patients with IIH share other symptoms with CFS apart from headache and fatigue â&#x20AC;&#x201C; dizziness, anxiety, depression, arthralgias, for example â&#x20AC;&#x201C; all regarded as non-specific.7,16,17 Nevertheless, these cases raise the possibility that there might be some overlap between the two syndromes. Clearly, this paper describes preliminary work. We present a series of observations on patients with chronic fatigue, which is essentially a survey of intracranial pressure at a fairly random point in their illness when headache was severe. There is no contemporaneous control group. Instead, we have relied on historical controls in the form of accepted normative data for intracranial pressure. This is a deficiency but, having said that, what controls would be appropriate against our patient group? Not patients with chronic fatigue without headache because some patients with IIH have no headache. Not patients with headache but without fatigue because some of these patients also might have IIH. Healthy volunteers perhaps? Even the issue of what constitutes normal CSF pressure is contentious. For research purposes, defining raised intracranial pressure as 25 cm H2O or greater usefully excludes normals from a study group. In clinical practice, however, levels of up to 28 cm H2O may be accepted as normal. Yet, the studies that inform this normative

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data either include patients with headache18 or conspicuously fail to exclude them19 – a testament to hubris if ever there was one. Characterisation of headache in this series is poor; something also that could be levelled as criticism. This was deliberate. Headache in IIH is non-specific and can mimic named headache syndromes.8,12,13,14,15 So, we saw no point in trying to stratify patients into different headache types. This would normally be considered a handicap – a strategy likely to diminish the chance of producing a statistically useful result. Yet, we still found unequivocal IIH in 15% of our patient group. Patient selection was also ‘unscientific’. That is, it was at the discretion of one of the authors who was running the clinic (Prof. Lever), on the basis of headache being a prominent feature in their illness. Might there have been something else in the history or clinical examination that was offering a clue to the diagnosis of IIH that would have been picked up by any competent physician? This is difficult to refute except to reiterate that the decision to extend the diagnostic work-up of these particular patients was one of policy, developed in recognition that patients with IIH were probably being missed. Moreover, none of the patients referred for lumbar puncture had any signs of raised intracranial pressure, even in retrospect. It should be appreciated that this work is not an attempt to establish the prevalence of IIH in patients with CFS. It is an exploration of the possibility that the two conditions might be related or, at least, that IIH is being routinely overlooked. To answer these questions as efficiently as possible we selected patients with chronic fatigue in whom IIH was most likely to be found – that is, patients in whom headache was a prominent symptom. Inevitably, this means that the results may not be more widely applicable. Nevertheless, with a pick-up rate of 40% for IIH by some criteria and, at 19 cm H2O, a mean CSF pressure only one point short of the same upper limit of normal, it suggests that the issue would benefit from further study. Finally, it is worth addressing one particular further comment raised in the review process questioning the value of associating CFS with IIH – two difficult diseases, which are poorly understood. We answer this by saying that while our findings may seem to be little more than exchanging one condition of unknown aetiology for another, there is at least little question that IIH is a disease with an organic basis – something that should raise questions about the nature of CFS. It could also open the door to new treatments.20,21,22,23,24

Conclusion

Some patients with headache and a diagnosis of CFS have unrecognised and occult IIH.

The possibility that the two conditions are related cannot be excluded.

Acknowledgements

Earlier versions of this article were rejected by The Lancet, Archives of Internal Medicine, The British Journal of Psychiatry, Cephalalgia and BMJ Open. We are grateful to the editors of these journals and to their reviewers, as well as to the editor and reviewers of the JoOPM, for their comments, which have allowed us to answer some of their concerns in the current version, even if not completely resolving them.

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Conflict of interest disclosures

There are no conflicts of interest. This work was unfunded.

References 1. Fukuda, K., Straus, S. E., Hickie, I., Sharpe, M. C., Dobbins, J. G., & Komaroff, A. The chronic fatigue syndrome: a comprehensive approach to its definition and study. International Chronic Fatigue Syndrome Study Group. Ann Intern Med. 1994, 121(12):953–959. 2. Wessely, S., Chalder, T., Hirsch, S., Wallace, P., & Wright, D. The prevalence and morbidity of chronic fatigue and chronic fatigue syndrome: a prospective primary care study. Am J Public Health. 1997, 87(9):1449–1455. 3. Evengård, B., Schacterle, R. S., & Komaroff, A. L. Chronic fatigue syndrome: new insights and old ignorance. J Intern Med. 1999, 246(5):455–469. 4. Wall, M., & George, D. Idiopathic intracranial hypertension. A prospective study of 50 patients. Brain. 1991, 114:155–180. 5. Sussman, J. D., Sarkies, N., & Pickard, J. D. Benign intracranial hypertension. Pseudotumour cerebri: idiopathic intracranial hypertension. Adv Tech Stand Neurosurg. 1998, 24:261–305. 6. Friedman, D. I., & Jacobson, D. M. Diagnostic criteria for idiopathic intracranial hypertension. Neurology. 2002, 59(10):1492–1495. 7. Binder, D. K., Horton, J. C., Lawton, M. T., & McDermott, M. W. Idiopathic intracranial hypertension. Neurosurgery. 2004, 54(3):538–551. 8. Marcelis, J., & Silberstein, S. D. Idiopathic intracranial hypertension without papilledema. Arch Neurol. 1991, 48(4):392–399. 9. Farb, R. I., Vanek, I., & Scott, J. N. et al. Idiopathic intracranial hypertension: the prevalence and morphology of sinovenous stenosis. Neurology. 2003, 60(9):1418–1424. 10. Higgins, J. N., Gillard, J. H., Owler, B. K., Harkness, K., & Pickard, J. D. MR venography in idiopathic intracranial hypertension: unappreciated and misunderstood. J Neurol Neurosurg Psychiatry. 2004, 75(4):621–625. 11. Higgins, J. N., Tipper, G., Varley, M., & Pickard, J. D. Transverse sinus stenoses in benign intracranial hypertension demonstrated on CT venography. Br J Neurosurg. 2005, 19(2):137–140.

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12. Mathew, N. T., Ravishankar, K., & Sanin, L. C. Coexistence of migraine and idiopathic intracranial hypertension without papilledema. Neurology. 1996, 46(5):1226–1230. 13. Torbey, M. T., Geocadin, R. G., Razumovsky, A. Y., Rigamonti, D., & Williams, M. A. Utility of CSF pressure monitoring to identify idiopathic intracranial hypertension without papilledema in patients with chronic daily headache. Cephalalgia. 2004, 24(6):495–502. 14. Bono, F., Messina, D., & Giliberto, C. et al. Bilateral transverse sinus stenosis predicts IIH without papilledema in patients with migraine. Neurology. 2006, 67(3):419–423. 15. Bono, F., Messina, D., & Giliberto, C. et al. Bilateral transverse sinus stenosis and idiopathic intracranial hypertension without papilledema in chronic tension-type headache. J Neurol. 2008, 255(6):807–812. 16. Kleinschmidt, J. J., Digre, K. B., & Hanover, R. Idiopathic intracranial hypertension: relationship to depression, anxiety, and quality of life. Neurology. 2000, 54(2):319–324. 17. May, M., Emond, A., & Crawley, E. Phenotypes of chronic fatigue syndrome in children and young people. Arch Dis Child. 2010, 95(4):245–249. 18. Whiteley, W., Al-Shahi, R., Warlow, C. P., Zeidler, M., & Lueck, C. J. CSF opening pressure: reference interval and the effect of body mass index. Neurology. 14 November 2006, 67(9):1690–1691. 19. Avery, R. A., Shah, S. S., Licht, D. J., Seiden, J. A., Huh, J. W., Boswinkel, J., Ruppe, M. D., Chew, A., Mistry, R. D., & Liu, G. T. Reference range for cerebrospinal fluid opening pressure in children. N Engl J Med. 26 August 2010, 363(9):891–893. 20. Higgins, J. N., Owler, B. K., Cousins, C., & Pickard, J. D. Venous sinus stenting for refractory benign intracranial hypertension. Lancet. 2002, 359(9302):228– 230. 21. Higgins, J. N., Cousins, C., Owler, B. K., Sarkies, & N., Pickard, J. D. Idiopathic intracranial hypertension: 12 cases treated by venous sinus stenting. J Neurol Neurosurg Psychiatry. 2003, 74(12):1662–1666. 22. Donnet, A., Metellus, P., & Levrier, O. et al. Endovascular treatment of idiopathic intracranial hypertension: clinical and radiologic outcome of 10 consecutive patients. Neurology. 2008, 70(8):641–647. 23. Bussière, M., Falero, R., Nicolle, D., Proulx, A., Patel, V., & Pelz, D. Unilateral transverse sinus stenting of patients with idiopathic intracranial hypertension. Am J Neuroradiol. 2010, 31(4):645–650.

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24. Ahmed, R. M., Wilkinson, M., & Parker, G. D. et al. Transverse sinus stenting for idiopathic intracranial hypertension: a review of 52 patients and of model predictions. Am J Neuroradiol. 2011, 32(8):1408–1414. Contacts/correspondence Dr Nicholas Higgins, Consultant Neuroradiologist, Department of Radiology, Box 219, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 0QQ, UK E-mail: nick.higgins@addenbrookes.nhs.uk

Intellectual property & copyright statement We as the authors of this article retain intellectual property right on the content of this paper. We as the authors of this paper assert and retain legal responsibility for this paper. We fully absolve the Editors and Company of JoOPM of any legal responsibility from the publication of our paper on their website. Copyright 2013. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Can the MMPI-2 detect exaggeration in personal injury cases? A brief outline Dr Kari S. Carstairs BA (Hons) Oxon MA PsyD CPsychol CUEW ABAP

1

Abstract I will provide a brief overview of the validity scales from the MMPI-2 and discuss three research studies using these scales with personal injury claimants. I will then present three cases to illustrate how the test can assist in the detection of exaggeration. Keywords MMPI-2, exaggeration, personal injury, claimants

Introduction The original Minnesota Multiphasic Personality Inventory (MMPI) was published in 1943 and it was revised in 1989 when it became known as the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) (Butcher, Graham, Ben-Porath, Tellegen, Dahlstrom & Kaemmer, 2001). It is an empirically based self-report measure for detecting mental health and personality problems. It consists of 567 statements to which the respondent answers ‘true’ or ‘false’. It has a normative sample of 2,500 adults in the USA and it has been translated into many different languages, from Arabic to Swedish. The published research on the test exceeds 18,000 research studies, and it has been validated with large samples in inpatient and outpatient mental health and forensic settings. More than 700 of those studies focus on response style. Response style refers to how the test items are answered and addresses whether the respondent tends to report symptoms consistently and openly, or to minimise distress and be defensive, or to exaggerate and overemphasise distress. Assessment of response style is important in determining how to interpret self-report measures, especially in cases where the respondent has a vested interest in the outcome of the evaluation, as in all evaluations for a personal injury claim. Exaggeration refers to over-reporting symptoms and/or the level of distress, without making any assumptions about the underlying motivation. Diagnostically, a distinction is made in the DSM-IV (American Psychiatric Association, 2000) between whether exaggeration is occurring consciously and deliberately or whether it is occurring unconsciously. If it is conscious, there are two diagnostic possibilities – malingering, where exaggeration occurs intentionally for some external gain (such as financial compensation) and factitious disorder, where it occurs in order to assume the role of patient. If it is unconscious, then the diagnostic possibilities are contained within the somatoform disorders and they include somatisation and hypochondriasis. This distinction between conscious and unconscious exaggeration requires one to make a clinical inference: testing alone cannot answer this issue. 1

Carstairs Psychological Associates Limited. Journal of Observational Pain Medicine – Volume 1, Number 2 (2013) ISSN 2047-0800


In this brief outline, I will discuss how the MMPI-2 can assist in establishing whether exaggeration is occurring (without inferring anything about the underlying motivation), using three case examples. For those who want to read further, a good introduction is given in Greene (2008).

The MMPI-2 scales that assess exaggeration The MMPI-2 contains ten main clinical scales and nine validity scales. There are also content scales, supplementary scales and critical items. Scoring of all of the scales is objective and can be done by computer. The validity scales allow the clinician to determine whether the clinical scales are likely to provide a reliable and valid indication of the examinee’s current psychological functioning. They address the consistency and accuracy of the examinee’s self-report. Consistency relates to whether the examinee responded reliably across the 567 items that make up the test and accuracy relates to whether the examinee distorted his or her responses to the items in some specific manner. Without consistency, there can be no accuracy. If the levels of inconsistency or distortion become too great, the clinical scales are not interpreted.

Table 1 – List of the validity scales on the MMPI-2

Scale notation ? scale L scale S scale F scale K scale Fb scale Fp scale VRIN scale TRIN scale

Name of scale Cannot say scale Lie scale Superlative self-presentation scale Infrequency scale Subtle defensiveness scale Back-page infrequency scale Infrequency psychopathology scale Variable response inconsistency scale True response inconsistency scale

Consistency is assessed with the ‘cannot say’ scale, the VRIN and the TRIN. The ‘cannot say’ scale is simply the number of items where the examinee did not give a response or where he or she answered both ‘true’ and ‘false’. If this number exceeds 30 items, the reliability of the results is in question and the rest of the scales are not interpreted. In practice, this outcome can usually be avoided by having the examiner inspect the answer sheet before terminating testing and if there are several ‘cannot say’ items, the examiner requests that the examinee return to these items and determine what the answer is. Both VRIN and TRIN consist of pairs of specially selected items. The TRIN scale relates to whether the examinee tends to answer ‘true’ or ‘false’, regardless of item content. It consists of pairs that are opposite in content, so if an examinee answers ‘true’ to both, one point is added and if he or she answers ‘false’ to both, one point is subtracted. Therefore, a high TRIN score indicates that the examinee tended to answer ‘true’ indiscriminately, whereas a low score indicates that he or she tended to answer ‘false’ indiscriminately. The VRIN scale consists of pairs of items where some pairs are similar in content and some are opposite, and each pair is scored for the occurrence of an inconsistency in the responses to the two items.

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When considering accuracy of responding, the remaining six scales are inspected. There are two main issues for the clinician to consider: defensiveness and exaggeration. Defensiveness is usually more common in cases for the family courts. In personal injury cases, the most common concern is whether the examinee has exaggerated and the remainder of this paper will focus on this. There are three main measures of exaggeration on the MMPI-2. The first is the F scale, known as the Infrequency scale. This consists of 60 items that are contained within the first 370 items of the booklet. These 370 items contain the ten main clinical scales. The 60 items on the F scale are endorsed by no more than 10% of the normative sample. The second measure is the Fb scale, known as the Back-page infrequency scale because it consists of 40 items that are contained in the items from 371 to 567, and once again, these items are endorsed by no more than 10% of the normative sample. The fact that there are two scales, one in the earlier items and one in the later items, enables the clinician to gauge whether the examinee’s response style may have shifted over time, which is useful given the length of the test. On average, it takes about an hour and a half to two hours to complete all of the items. Sometimes, examinees stop paying attention and shift to an essentially random pattern of responding over time. If this happens, there will be a difference between the F scale and the Back F scale, alerting the clinician that the ten main clinical scales in the first 370 items are interpretable but the remaining supplementary and content scales contained in the other, later items are not. The third measure of exaggeration on the MMPI-2 is the Fp scale or Infrequency psychopathology scale. This consists of 27 items that are endorsed by fewer than 20% of psychiatric inpatients.

Some research on exaggeration and F, Fb and Fp There is a very substantial body of research on these scales. An overview of it is given in Pope, Butcher & Seelen (2006) and in Bagby, Marshall, Bury, Bacchiochi & Miller (2006). I will provide an outline of three studies with patients who are seeking compensation that illustrate some of the findings that are contained within this body of research. Arbisi, Ben-Porath & McNulty (2006) investigated the ability of the MMPI-2 to detect feigned reports of post-traumatic stress disorder (PTSD) in a group of veterans seeking compensation. They recruited male veterans who were applying for compensation for PTSD and who had completed a valid MMPI-2 as part of the evaluation. These veterans were asked to complete the test again under one of two scripted conditions: (1) fake PTSD and avoid detection (35 men); and (2) the standard instructions (55 men). Over-reporting scales were examined to assess their ability to distinguish between the two groups. The results showed that the veterans who were instructed to exaggerate or feign PTSD produced elevated scores on the MMPI-2 clinical and content scales when compared with those who followed the standard instructions. Furthermore, those instructed to exaggerate produced significantly higher scores on F, Fb and Fp, with Fp producing the highest effect size. Multiple regression analysis showed that Fp alone accounted for 42% of the variance when differentiating between veterans instructed to respond honestly and those instructed to exaggerate. The authors drew up classification accuracy tables based on their findings and reported that at the recommended cut-off of t ≥ 100, Fp accurately classified 85% of the veterans with a base rate of 30%. This is the estimated base rate of exaggeration in the population of

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veterans seeking compensation. The authors concluded that regardless of compensation-seeking status, an elevation of the Fp scale that exceeds a t score of 90 should begin to raise concerns about over-reported PTSD symptoms. The use of participants who are instructed to exaggerate is an experimental manipulation, which may not translate into the clinical situation and there is some indication that as the ecological validity of the comparison increases, the effect sizes decrease (Berry, 1995). It is, therefore, important to look at research findings from mixed clinical groups. Tolin, Steenkamp, Marx & Litz (2010) studied the MMPI-2 results for 377 male veterans who were claiming compensation for PTSD in a different research design using a mixed group thought to contain both exaggerating and honest responders, using different estimates for the base rate for symptom exaggeration. The results indicate that cut-off t scores of > 90 for F and Fb and > 60 for Fp were able to demonstrate adequate sensitivity, specificity and efficiency across different base rates. Bianchini, Etherton, Greve, Heinly & Meyers (2008) investigated the accuracy of the MMPI-2 validity indicators in the detection of malingering in clinical patients with chronic back or neck pain. Their sample consisted of: (i) 23 patients with no financial incentive; (ii) 34 patients who were considered to be genuine but who had a financial incentive; (iii) 32 patients who had been determined to be malingering; and (iv) 26 college students asked to simulate a pain-related disability. Members of the second group had completed two or more forced-choice symptom validity tests and were negative on all available validity indictors, and all 34 of them had objective clinical evidence of spinal pathology. Members of the third group performed below chance on at least one forced-choice symptom validity test or presented with a compelling inconsistency between his or her self-report and objective findings. The students were given instructions on faking. The results show that MMPI-2 scales and indicators were able to differentiate between non-malingering and intentionally exaggerating participants. The authors provide tables showing the cumulative percentages of patients with scores above the indicated t score for the validity scales and for clinical scales that relate to somatisation. They conclude their paper with some discussion about how to differentiate between those patients who are responding to the context of making a compensation claim but who are not deliberating exaggerating and those who are, noting that their results show that extreme scores reflect intentional exaggeration. The authors end with a caution that the MMPI-2 results need to be put in context with the rest of the clinical data.

Three case examples In this section, I will present three clinical cases from our clinical practice that illustrate how the MMPI-2 findings can be interpreted in context.

Case one The first case is of a 61-year-old man who was making a medical negligence claim. He had a history of chest pain and was fitted with a pacemaker but this was later found to have been unnecessary. He actually had a tumour on his pituitary gland. There was no previous psychiatric history and no reason from the background information to question the validity of his self-report. He approached the evaluation with a straightforward presentation, reporting some symptoms and denying several others. This is a valid profile (see Figure 1), with all scores falling solidly in the average range. These results provide confirmation of the general clinical picture that this man is very likely to be an entirely genuine claimant, with no evidence of any exaggeration.

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Figure 1 â&#x20AC;&#x201C; Validity scales for case one

Case two The second case is of a 52-year-old woman who was also making a medical negligence claim. She had a history of multiple operations, including a total abdominal hysterectomy, and two total mastectomies. There was some question from the doctors about whether all these procedures were necessary. She was then diagnosed with fibromyalgia. Four years before the evaluation, she was complaining of abdominal pain. She ended up having a colostomy. Medical evidence showed that this was performed negligently in that the wrong end of the colon had been brought out. This was then corrected surgically. The client was alleging PTSD, depression and chronic pain as a result of this experience. There was a previous history of panic attacks several years before the surgery and also a history of depression after the mastectomies. In addition, there was a childhood history of significant sexual abuse and neglect. This client dwelled on her symptoms at length in the interview and was distressed and tearful. She was preoccupied with her account of the medical procedures she had had, whereas she was more reluctant to talk about her psychosocial situation. She was single, with no children. She was not working and she stated that she was unable to work because of her medical condition. She was resistant to the idea that she might benefit from psychological treatment, stating that she preferred to take medication. This profile (see Figure 2) is consistent with the conclusion that this woman is exaggerating her report of her symptoms. F and Fb are both highly elevated, above the cut-off scores that research studies indicate yield good classification rates.

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Figure 2 – Validity scales for case two

Furthermore, Fp is also very high, at a t score of 97, which is above the recommended cut-off scores of either 60 or 90 in the studies reviewed above. Tables provided by Greene (2008) show that a raw score of 7 on Fp occurred in none of the normal individuals and in only 2% of the patients in clinical settings. Resnick, West & Payne (2008) summarise the findings from eight studies using the MMPI-2 to investigate how to distinguish between genuine PTSD and malingering, and report that these studies revealed that there is a 91% likelihood that a person is feigning when scores exceed a cut-off score of Fp > 8 (raw score). The score that this claimant obtained is just one point shy of this and her t score of 97 is above Resnick, West & Payne’s recommended t score cut-off of 96. The history also suggests that this claimant’s presentation is complex, with many factors that may be driving her report of distress. The MMPI-2 findings should not necessarily be taken to mean that she is not distressed but they do undermine the claim that all of her distress should be linked to the recent negligent medical procedure. A history of sexual abuse in childhood is a known risk factor for the development of chronic pain (Sachs-Ericsson, Kendall-Tackett & Hernandez, 2007) and she may well have PTSD and depression as a result of this early history.

Case three The third case is of a 33-year-old man who was making a personal injury claim after a road traffic accident in which he was nearly killed. He suffered a whiplash injury of his neck and severe bruising to his chest. He was referred to the pain clinic when the pain in his neck did not settle and he was on a waiting list for admission to this service. He stated that he was unable to return to work as a builder due to the pain.

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The strenuous physical demands of this type of work would exacerbate the pain. He felt anxious about losing his source of income, particularly because he had a young family to support. He had had some sessions of psychotherapy in relation to symptoms of PTSD before the evaluation. He reported that he found these helpful and this treatment was ongoing. The treating psychologist confirmed that he had engaged well in the treatment and he was making progress. He reported that he had been apprehensive about coming to the appointment because he did not want to ‘drag it all up again’. He appeared to find it embarrassing when he got tearful as he spoke of the accident, stating that he had never had such problems in the past. His GP records confirmed that there was no previous history of any psychological problems prior to the accident. This profile (see Figure 3) presents a mixed picture. Looking at F and Fb, there is some indication that he may have been exaggerating. The t scores for both of these scales are above the cut-off of 90 that Tolin, Steenkamp, Marx & Litz (2010) recommend. However, Resnick, West & Payne (2008) set a higher cut-off, above a t score of 107 for these two scales and furthermore, Fp is within the average range. A reasonable conclusion from these results is that this claimant was focused on his symptoms during the evaluation and may have had a mild tendency to exaggerate but, overall, his self-report is likely to be reliable. His clinical presentation and the background information were consistent with this conclusion. Figure 3 – Validity scales for case three

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Conclusion The MMPI-2 is an objective, statistically based method for the assessment of exaggeration and other response styles. It has a very large body of research to support its use when assessing claimants in personal injury claims. It is effective at distinguishing between those claimants who are responding honestly from those who are very likely to be exaggerating. The final determination of exaggeration should be established by combining the results of the MMPI-2 with other test results, interview data and background information.

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References American Psychiatric Association (2000). Diagnostic and Statistical Manual of Mental Disorders (Fourth Edn: text revision). Washington, DC: Author. Arbisi, Paul A., Ben-Porath, Yossef S., & McNulty, John (2006). The ability of the MMPI-2 to detect feigned PTSD within the context of compensation seeking. Psychological Services, 3, pp. 249–261. Bagby, R. Michael, Marshall, Margarita B., Bury, Alison S., Bacchiochi, Jason R., & Miller, Lesley S. (2006). Assessing underreporting and overreporting response styles on the MMPI-2. In James N. Butcher (ed.), MMPI-2: A Practitioner’s Guide, American Psychological Association: Washington, DC, pp. 39–69. Berry, David T. (1995). Detecting distortion in forensic evaluations with the MMPI-2. In Yossef S. Ben-Porath, John R. Graham, Gordon C. N. Hall, Richard D. Hirschman & Maria S. Zaragoza (eds.), Forensic Applications of the MMPI-2. Sage Publications: Thousand Oaks, CA, pp. 82–102. Bianchini, Kevin J., Etherton, Joseph L., Greve, Kevin W., Heinly, Matthew T., & Meyers, John E. (2008). Classification accuracy of MMPI-2 validity scales in the detection of painrelated malingering: A known-groups study. Assessment, 15, pp. 435–449. Butcher, James N., Graham, John R., Ben-Porath, Yossef S., Tellegen, Auke, Dahlstrom, W. Grant, & Kaemmer, Beverly (2001). MMPI-2 Minnesota Multiphasic Personality Inventory2™ Manual for Administration, Scoring and Interpretation: Second Edition. University of Minnesota Press: Minneapolis, MN. Greene, Roger (2008). Malingering and defensiveness on the MMPI-2. In Richard Rogers (ed.), Clinical Assessment of Malingering and Deception: Third Edition, The Guilford Press: London, pp. 159–181. Pope, Kenneth S., Butcher, James N., & Seelen, Joyce (2006). The MMPI, MMPI-2, and MMPI-A in Court: Third Edition: A Practical Guide for Expert Witnesses and Attorneys. American Psychological Association: Washington, DC. Resnick, Phillip J., West, Sara, & Payne, Joshua W. (2008). Malingering of post-traumatic disorders. In Richard Rogers (ed.), Clinical Assessment of Malingering and Deception: Third Edition, The Guilford Press: London, pp. 109–127. Sachs-Ericsson, Natalie, Kendall-Tackett, Kathleen, & Hernandez, Annya (2007). Childhood abuse, chronic pain and depression in the National Comorbidity Survey. Child Abuse & Neglect, 31, pp. 531–547. Tolin, David F., Steenkamp, Maria M., Marx, Brian P., & Litz, Brett T. (2010). Detecting symptom exaggeration in combat veterans using the MMPI-2 symptom validity scales: A mixed group validation. Psychological Assessment, 22, pp. 729–736. Contacts/correspondence Dr Kari S. Carstairs, 7 Mayfield Road, Bromley, Kent, BR1 2HB E-mail: kari@carstairspsych.co.uk

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Intellectual property & copyright statement I as the author of this article retain intellectual property right on the content of this paper. I as the author of this paper assert and retain legal responsibility for this paper. I fully absolve the Editors and Company of JoOPM of any legal responsibility from the publication of my paper on their website. Copyright 2013. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited.

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Surgery for lumbar intervertebral disc prolapse in a patient with complex regional pain syndrome Dr Christopher Green MB BCh FRCA FFPMRCA FFMLM 2 Dr George Evans MD FRCPC

1

Abstract We report a rare case of complex regional pain syndrome (CRPS) type II in a 54-yearold male patient, which was thought to occur secondary to prolapsed intervertebral disc compression of a lumbar nerve root, and which was previously misdiagnosed as CRPS I secondary to a crush injury. Symptoms were difficult to manage by conventional means but successful resolution of the CRPS features was attained after incorporating surgical decompression into his management, with a consequent increase in the patientâ&#x20AC;&#x2122;s function. It is widely held that surgery in the presence of CRPS, especially on an affected limb, can cause a flare of the condition and complicate surgical outcome. Conversely, it has also been argued that where CPRS is classed as type II, the identification of pain generators may allow treatment, which could reduce the continued sensitising processes and wind-up phenomenon which otherwise result in the persistence of CRPS symptoms. After review of the literature, we could find no definitive evidence to support not operating in the presence of CRPS and so we rationalised utilising surgical decompression. This was successfully undertaken and helped resolve the CRPS features the patient exhibited, allowing him to become more functional and participate in physical therapy. Often there is little clinical reason to distinguish CRPS type I from II, and this may explain why surgical methods to assist in the management of CRPS have anecdotally failed. Employing such a management strategy requires that this distinction is made accurately, allowing for diagnostic blocks later, which are thought to play a central role in identifying potential pain generators. Keywords Complex regional pain, CRPS, spinal surgery, disc prolapse

Introduction Complex regional pain syndrome (CRPS) is a severe form of neuropathic pain, which can be difficult to manage. Diagnosis is largely clinical and still being refined. Management is multidisciplinary and focuses on symptom management and functional restoration through psychological, physical, pharmacological and interventional approaches. Traditionally, operations in patients with CRPS are avoided for fear of exacerbating their pain syndrome or complicating surgical outcome. Such patients exhibit central wind-up of their sensory system and are felt to be at risk of developing other pain syndromes in such cases. We report a case of CRPS, which was felt to be caused by prolapsed intervertebral disc compression of a nerve root and was difficult to manage by conventional means. 1 2

Pain Fellow, the Ottawa Hospital, Ottawa, Canada & SpR Oxford Deanery, UK (at the time of writing). Staff (Consultant) in Anaesthesia and Pain Medicine, the Ottawa Hospital, Ottawa, Canada. Journal of Observational Pain Medicine â&#x20AC;&#x201C; Volume 1, Number 2 (2013) ISSN 2047-0800


Surgical decompression was used to aid in the management, which helped successfully resolve the CRPS features the patient exhibited. Though it did not completely resolve the patient’s pain, it was significantly reduced. He was also able to increase his functional activity levels and consume less opiates.

Case report A 54-year-old man presented with a six-year history of right back and leg pain following an accident at work in which he sustained a crush injury to his leg as it was caught between two closing security doors. A year later, he suffered another injury when he sustained a fall at work tripping over a power cable. This aggravated his pain further. Unfortunately, he sustained a third accident when his work chair collapsed from underneath him, causing further exacerbation of his pain. On presentation to the pain clinic six years after his initial injury, the patient characterised his back and leg pain as a dull, aching pressure with throbbing, stabbing periods together with a burning sensation. These were associated with tingling sensations and numbness in the affected areas. He rated his pain on the Brief Pain Inventory (BPI) as averaging 4 out of 10, ranging from 1 to 10 out of 10. His pain was exacerbated by prolonged sitting and standing, bending, lifting, coughing and sneezing. It was relieved by heat and lying down with his feet elevated above his head. He also had a history of discolouration of the affected limb, temperature sensitivity, increased sweating and sensitivity to light touch, both hypersensitivity and allodynia. He did not describe trophic hair, skin or nail changes. There were no red flag features. Sleep was greatly disturbed and his mood was generally poor with self-confessed frustration and mild anger at his condition. He rated his interference factors from the pain on the BPI as 10 out of 10 for all accept mood, which he rated as 7 out of 10. His medications, particularly secondary analgesics, gave him approximately 80% relief. These included Naproxen, Oxycocet, Oxycontin and Pregabalin. He also took Zopliclone and Trazodone. He had previously tried steroid burst therapy elsewhere, which reduced his pain for a few days. Blind interlaminar epidurals had also been tried before with little effect. He was unable to participate with general physiotherapy due to the severity of his pain. Socially, the patient continued to work in information technology by working predominantly from home, though this was becoming increasingly problematic. He did receive workers compensation benefits. He smoked but did not consume alcohol. There were no features in his history to suggest risk of aberrant drug use apart from marijuana use 30 years previously. Specifically, there was no history of excessive alcohol use, illicit drug use other than marijuana, psychiatric disorders, sexual abuse or positive family history for the same. Examination demonstrated the patient to be in obvious discomfort at rest. He walked with the aid of a stick with an antalgic gait. Observation of the limb and spine did not show any deformity, swelling or trophic changes. His right foot was colder than the left by 1º C. Sensation to light touch was increased over the lateral border of the right lower leg. The right leg demonstrated a general reduction in range of motion, especially in the foot, and was generally weak throughout compared with the left. Straight leg raise was positive at 30º on the right. Crossed straight leg raise was negative. Investigations already performed on the patient included an EMG and MRI. The EMG did not demonstrate a significant abnormality, according to the patient, though

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we did not have the results available to us. However, the MRI from three years previously demonstrated a broad-based disc protrusion with far lateral component causing L4/5 foraminal stenosis and abutting the L4 nerve root, but without nerve root compression. The initial management of the patient after rationalisation of his medications and the addition of a low-dose Tricyclic antidepressant, was to perform a right lumbar sympathetic block, pending repeat imaging of his lumbar spine. This gave the patient good relief from his pain but was short-lived. Repeat MRI of his lumbar spine then demonstrated a large sequestered disc at the L4/5 level with posterolateral herniation causing L4 nerve root compression. Due to the high correlation of symptoms, signs and imaging, the patient then underwent a lumbar transforaminal epidural steroid injection at the L4/5 level in the hope that this would extend his period of analgesia and increase the efficacy of the lumbar sympathetic blocks. His pain was again relieved by at least 50%, but was similarly short-lived. This was in contradiction to the previously tried, and less evidenced, interlaminar approach, which was perhaps not unexpected. The positive effect of local anaesthetic blocks and the strong correlating clinical features led to subsequent referral for L4/5 microdiscectomy and L5 nerve root decompression, which was carried out uneventfully utilising a standard right-sided paraspinal muscle-stripping approach. Unfortunately, this was performed at another site with minimal delay from referral, meaning that liaison with an anaesthesiologist experienced in pain medicine was not achieved preoperatively. The patient, therefore, did not receive any additional neuropathic pain protective or pre-emptive measures. Despite this, he had a good outcome. He underwent post-operative physiotherapy with emphasis on CRPS management. Follow-up in the pain clinic at four weeks post-operatively demonstrated improved pain with less frequent and less severe flares of his pain, which he rated from 1 to 6 out of 10 on the BPI. He also exhibited less hypersensitivity and allodynia, with no further swelling or colour changes to his affected limb. He was able to mobilise more effectively and reported walking around the local shopping mall for the first time in many years. Furthermore, there was a reduction in his opiate requirements. He did report some low back and buttock pain, which was attributed to post-operative musculoskeletal pain. These improvements were maintained at three months, though he also started to describe associated groin pain, which was felt maybe due to early post-operative epidural scarring, and so he was offered transforaminal epidural steroids. His progress continues to be followed in the pain clinic for his chronic pain management, though the severe features of his CRPS have resolved. It should be noted that he was considered for spinal cord stimulation preoperatively, but after prolonged discussion with the patient it was felt that he should undergo surgical management and if his pain was still significant afterwards then spinal cord stimulation could still be considered.

Discussion CRPS is considered by some to be one end of a spectrum of neuropathic pain. Defining features are given by the International Association for the Study of Pain and were further revised by the diagnostic criteria produced by Harden et al. in 2007.1,2 More recently the Budapest diagnostic criteria have been demonstrated to improve diagnostic sensitivity and specificity. These include continuing pain which is out of proportion to any inciting event, with patients reporting one symptom in 3 out of 4

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categories, as well as demonstrating at least one sign in 2 out of 4 categories at the time of evaluation, in the absence of any other condition that could better explain the clinical findings.3 Our patient demonstrated these features and as such was given the diagnosis of CRPS. Where the diagnosis is in doubt, or where further supportive evidence is required, investigations can be helpful. These include the use of bone scans, thermography, quantitative sensory testing, sudomotor testing and EMG studies. EMG, in particular, is useful for aiding in distinguishing between CPRS types I and II. Even so, correctly diagnosing CRPS type I from II can, in many cases, be difficult or overlapping. It can be argued that this distinction is rarely clinically important, unless an ongoing pathophysiological mechanism for neuronal injury is found which is amenable to direct therapy. Management of CRPS can generally be divided into concomitant administration of physical and psychological therapy, pharmacological therapy and interventions aimed at neuromodulation in a multidisciplinary approach. Most of these focus on the functional restoration of the affected individual or limb through conventional analgesia, reduction in sympathetic mediation, enhancement of descending inhibition in the spinal cord, reduction in neuronal excitability, central reorganisation and cognitive coping. All of these methods address the CRPS process specifically rather than any inciting process. Indeed, in the majority of chronic pain cases, focusing on addressing an underlying cause in a mechanistic approach is either not possible or desirable for effective management in a biopsychosocial model. However, where there is ongoing pathology causing continuing damage in a progressive-acute manner with secondary chronic central changes, there is an argument for targeting these pain generators. Traditionally, however, where central changes have occurred to such an extent as to have resulted in the formation of a CRPS, the teaching has been that any further noxious-inciting event is at risk of worsening or re-establishing the condition and complicating the surgical outcome. A review of the literature by the current authors looking specifically at operations to target pain generators in CRPS type II could find little definite evidence for this traditional way of thinking as applied in this setting. Most would still agree that interventions during the acute Phase One period of the condition on an affected limb should be avoided, but there was little evidence to support non-intervention beyond this period or outside the affected area. Conversely, there is evidence for surgical correction of a correctly identified pain generator in helping to resolve neuropathic pain and CRPS symptoms. Pain generators are any pathological processes that cause continuing transmission of noxious stimuli. These may be neuromas, forming intrinsic neuronal pain generators, or external compression or inflammatory mediators acting on nerves, forming external neuronal pain generators. Prolapsed intervertebral discs conform to the latter category. As an example of pain generators in acute pain, and in neuropathic pain without CPRS features, they are well described, but they have only been described rarely as causes of CRPS.4,5,6,7 Where reported, however, each case is documented to have demonstrated a good outcome after surgical correction. This should not be as surprising as is first thought. Dellon et al. propose that chronic nerve compression produces continuing dorsal column stimulation, which acts to drive CRPS.8,9 Without removing this source there is little chance for the central changes of CRPS to wind down either spontaneously or with conventional management. Success for this approach, however, resides in accurate diagnosis of CRPS type II. The same authors suggest that many cases of failed surgical intervention could be due to CRPS type I being misdiagnosed as CRPS type II. It appears that successful local anaesthetic block can help with this dilemma, in

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cases of identifying peripheral nerve neuromas as causes for CRPS type II.10 Our case did have a transforaminal epidural steroid injection which failed to reduce his pain, but this may have been a result of the active drug not being able to get to the site of required action or more proximally. This is not an uncommon scenario, especially in long-standing calcified, sequestered herniated discs, as our patient had. He did not have a nerve root block, though this in unlikely to have been effective as the pathology was more proximal. A dense epidural or intrathecal block is likely to have been successful but would have lacked specificity. It would be prudent in cases identified as suitable for operative intervention for CRPS type II to provide good perioperative support in managing neuropathic pain by an anaesthesiologist experienced in pain medicine. Unfortunately, this was not the case with our patient, though he still had a positive outcome. Indeed, a retrospective study of 100 cases looking at surgery for pathology on the previously affected upper extremity of patients with a past history of CRPS of either type I or II which had subsequently resolved, found that perioperative sympathetic block reduced the risk of recurrence from 72% to 10% post-operatively at one year.11 The study is flawed by not being blinded, as well as not demonstrating the proportion of CRPS types I and II in each group, and by using two surgeons: one for the control and one for the sympathetic block arm. Nevertheless, the results support the usefulness of this approach. In summary, radicular pain in patients such as ours with CRPS should prompt a search for causes of CRPS type II. In our case, it appears retrospectively that he was misdiagnosed with CRPS type I secondary to his obvious crush injury, which should have been diagnosed as CRPS type II secondary to prolapsed intervertebral disc. The importance of this distinction is that the latter has an ongoing pain generator driving central sensitisation and wind-up phenomenon, resulting in the persistence of CRPS symptoms, whereas the former does not once tissue healing has occurred. It is possible that during the original injury severe paraspinal muscle spasm could have allowed for the formation of the prolapsed intervertebral discs and subsequent nerve root irritation. In such circumstances, consideration should be given to conventional surgical management of the prolapsed intervertebral disc, undeterred by the diagnosis of CRPS, with appropriate perioperative multidisciplinary support. In our case, failure to have considered this option would have likely resulted in the patient having a spinal cord stimulator and continued medication use. His symptoms may have continued to have got worse with time, eventually resulting in significant neurological impairment and disability from continued and ongoing nerve damage.

Conclusion In conclusion, this is one of only a few cases described in the literature of CRPS secondary to prolapsed intervertebral disc at the lumbar level treated successfully with surgical laminectomy. It demonstrates that in managing cases of CRPS type II, ongoing pain generators should not be overlooked and that surgery is not a contraindication in selected cases, but that this should ideally be timed in a coordinated way that allows multidisciplinary input to maximise the chance of a favourable outcome. Conflict of interest disclosures

None declared

References

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1. Harden, R. N., Bruehl, S., Stanton-Hicks, M., & Wilson, P. R. Proposed new diagnostic criteria for complex regional pain syndrome. Pain Med 2007, 8(4):326–331. 2. Mogil, J. S. (ed.). Pain 2010: An Updated Review. Seattle: IASP Press, 2010. 3. Validation of proposed diagnostic criteria (the ‘Budapest Criteria’) for Complex Regional Pain Syndrome. Pain 2010, 150(2):268–274. 4. Condon, F., Kenny, P. J., Griffin, J. G., O’Rourke, K. Reflex sympathetic dystrophy associated with extraforaminal disc herniation at the L5-S1 level. Journal of Spinal Disorders 1998, 11(5):448–451. 5. Bernini, P. M., Simeone, F. A. Reflex sympathetic dystrophy associated with low lumbar disc herniation. Spine 1981, 6(2):180–184. 6. Ballard, E. M., Ellenberg, M., & Chodoroff, G. Reflex sympathetic dystrophy syndrome secondary to L5 radiculopathy. Arch Phys Med Rehab 1991, 72:595–594. 7. Carlson, D. H., Simon, H., & Wegner, W. Bone scanning and diagnosis of reflex sympathetic dystrophy secondary of herniated lumbar discs. Neurology 1977, 27:791–793. 8. Dellon, A. L., Andonian, E., & Rosson, G. D. CRPS of the upper or lower extremity: surgical treatment outcomes. Journal of Brachial Plexus and Peripheral Nerve Injury 2009, 4:1. 9. Dellon, L., Andonian, E., & Rosson, G. Lower extremity complex regional pain syndrome: long-term outcome after surgical treatment of peripheral pain generators. The Journal of Foot and Ankle Surgery 2010, 49(1):33–36. 10. Stokvis, A., Van der Avoort, D. J., Neck, J. W., Hovius, S. E., & Coert, J. H. Surgical management of neuroma pain: a prospective follow-up study. Pain 2010, 151(3):862–869. 11. Reuben, S. S., Rosenthal, E. A., & Steinberg, R. B. Surgery on the affected upper extremity of patients with a history of complex regional pain syndrome: a retrospective study of 100 patients. J Hand Surg [Am] 2000, 25:1147–1151. Contacts/correspondence Dr C. Green, Locum Consultant, Department of Anaesthesia, Addenbrooke’s Hospital, Hills Road, Cambridge, CB2 0QQ E-mail: sevokit@gmail.com

Intellectual property & copyright statement We as the authors of this article retain intellectual property right on the content of this paper. We as the authors of this paper assert and retain legal responsibility for this paper. We fully absolve the Editors and Company of JoOPM of any legal responsibility from the publication of our paper on their website. Copyright 2013. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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The incidence of complex regional pain syndrome (CRPS) post trauma and the possible role of tight plaster of Paris in the aetiology of CRPS 1

Zahra Safarfashandi 2 Dr Rajesh Munglani MB BS DA DCH FRCA FFPMRCA 3 Dr Laila Safarfashandi MB BS BSC 4 Jamie Sadheura 5 Dr Christopher Jenner MB BS FRCA FFPMRCA

Abstract Keywords complex regional pain syndrome (CRPS), tight plaster of Paris (POP), trauma, immobilisation

Introduction What is the incidence of CRPS after trauma? The cause of complex regional pain syndrome (CRPS) is still unknown, although numerous risk factors have been identified. Commonly, noxious events such as limb trauma, with the commonest type being a fracture,1 or a nerve lesion2 precede the development of CRPS. The percentage of CRPS cases preceded by trauma has been quoted to vary from less than 1%3 up to 5–77%.4,5 In specifically examining the incidence of CRPS after fractures, Atkins suggested that 30–40% of patients go on to develop CRPS.4 There are limited numbers of studies assessing different fracture types and their incidences of CRPS; however, it has been suggested that wrist fractures lead to high rates of CRPS – 7–37%6 – with tibial fractures closely following with 30%.5 However, these rates probably suggest overdiagnosis because the early stages of trauma post-operatively are associated with the cardinal signs of inflammation, rubour, tumour, dolour and calour (redness, swelling pain and heat). These features are, of course, also the initial features of CRPS and, according to the Budapest criteria, which are far more stringent than the International Association for the Study of Pain (IASP) criteria, any other possible diagnosis or explanation for the symptoms should be considered first before invoking a diagnosis of CRPS.7,8 Yet, is it reasonable to consider early post-traumatic inflammation as a form of CRPS? It has been argued probably not because it has been shown that the type of inflammatory cells seen in CRPS differs from that of normal post-traumatic                                                                                                                       1

Imperial College London.

2

West Suffolk Hospital NHS Bury St Edmunds and Spire Lea Hospital Cambridge.

3

Ealing Hospital London.

4

University of Kent, Canterbury.

5

Imperial College Healthcare NHS Trust.

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inflammation which accumulates in the affected tissue. In post-traumatic inflammation, high lymphocyte and mast cells numbers are observed with increased histamine and cytokine release. Yet, in CRPS inflammation the large numbers of these cells expected is not observed.2

What are the diagnostic criteria for CRPS? The IASP has accepted that CRPS may be over-diagnosed. Diagnosis is based on clinical signs, and the diagnostic criteria have a sensitivity and specificity of 0.85 and 0.6 respectively.9 There is neither a gold-standard test nor any objective diagnostic tool as yet. The reason for the very large variation in incidence is due to the diagnostic criteria applied. If we look at the IASP diagnostic guidelines, they are split into four main categories:9 IASP diagnostic criteria for CRPS Type 1 (1994): (1) The presence of an initiating noxious event or cause of immobilisation. (2) Continuing pain, allodynia or hyperalgesia with which the pain is disproportionate to any inciting event. (3) Evidence at some time of oedema, changes in skin blood flow or abnormal sudomotor activity in the region of pain. (4) The diagnosis is excluded by the existence of conditions that would otherwise account for the degree of pain and dysfunction. Below are the four main categories with several examples for each:

Sensory signs and symptoms  increasing pain when the extremity is in a dependent position  stimulus-evoked pain  sensory abnormalities

Autonomic abnormalities  changes in skin temperature  swelling  vasodilation or vasoconstriction  hyperhydrosis or hypohydrosis

Trophic changes  increased or decreased hair growth  fibrosis  thin, glossy skin  osteoporosis

Motor abnormalities  weakness  coordination deficits  tremor  neglect-like symptoms or symptoms of disturbed body perception of the affected extremity

The IASP guidelines have caused much controversy with F. Birklein et al. going as far as to say that no trauma patient can be diagnosed with CRPS according to the guidelines because pain and hyperalgaesia can never be disproportionate to the

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inciting event.2 Overall, most other authors suggest alternative incidences of less than 1% (see Guide to Pain Management in Low Resource Settings, which is a now standard IASP text).3 The Budapest criteria ‘tightened up the criteria’, as follows. International consensus group Budapest (2005) – revised clinical diagnostic criteria for CRPS:8 (1) Continuing pain that is disproportionate to any inciting event. (2) Patient must report at least one symptom in 3 of the 4 categories: (a) Sensory: reports of hyperaesthesia and/or allodynia. (b) Vasomotor: reports of temperature asymmetry and/or skin colour changes and/or skin colour asymmetry. (c) Sudomotor/oedema: reports of oedema and/or sweating changes and/or sweating asymmetry. (d) Motor/trophic: reports of decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia and/or trophic change (hair, nail, skin). (3) Must display at least one sign at time of evaluation in 2 or more of the 4 categories: (In the more strict ‘research criteria’, at least one sign at time of evaluation in 3 or more of the 4 categories are required.) (a) Sensory: evidence of hyperaesthesia (to pin prick) and/or allodynia (to light touch and/or deep somatic pressure and/or joint movement). (b) Vasomotor: evidence of temperature asymmetry and/or skin colour changes and/or skin colour asymmetry. (c) Sudomotor/oedema: evidence of oedema and/or sweating changes and/or sweating asymmetry. (d) Motor/trophic: evidence of decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia and/or trophic change (hair, nail, skin). There is no other diagnosis that better explains the signs and symptoms. An even more fundamental difference is that, post trauma, the pain and swelling and other changes are usually in proportion to the magnitude of the injury, and as mentioned they improve rapidly. In contrast, in CRPS, the pain, swelling and other changes are often disproportionately great, with cases of minor trauma being associated with very severe pain, and signs and symptoms which endure. Thus, this leads many authors to conclude that post-operative inflammation is a very different process, with a generally benign outcome compared with the less certain outcome in developing CRPS.

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Why might application of plaster of Paris contribute to CRPS or CRPS-like symptoms? A common treatment for fractures involves immobilisation and casting with plaster of Paris (POP), both of which have also been suggested as separate risk factors for the development of CRPS.10 Controversy exists partly because some of the symptoms commonly seen in CRPS may be explained by immobilisation, disuse and the nature of traumatised cells.11,12. The number and lack of consistency of risk factors in the literature is problematic (see Table 1). This highlights the question of whether it is the fracture that leads to CRPS, regardless of the management of the injury, or immobilisation, or in some cases is it that too tight a POP cast is being applied, which results in adverse complications for the patient, including CRPS. Thus, the question as to the significance of the tight POP is contentious, and is not helped by the confused picture painted by current literature as to the pathophysiology and diagnosis of CRPS. This review aims to analyse the arguments and clarify the consensus made by research groups as to the significance of a tight POP and its effect on the aetiology of CRPS.

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Table 1 – Possible risk factors for the development of CRPS

1,7,10,12,13

Risk factors for the development of CRPS Caucasian Female Japanese origin Several fracture repositions Fracture immobilisation POP cast too tight Immobilisation for too long Neuro-psychiatric disorders Immobilisation Smoking Substance abuse Genetic factors Multiple sclerosis Hypermobility ACE inhibitor Migraines Osteoporosis

Immobilisation and casting are often essential parts of the management of fractures.14 A POP cast is applied to immobilise the affected area and prevent redisplacement and therefore mal-union of the fracture. Conversely, a POP cast can act as a restricting band around the limb and, should there be any swelling, will raise intra-compartmental pressure.15 One study suggested that in patients with too tight a cast two weeks post injury, there is a 60% greater chance of developing CRPS than in those with normal pressure casts at this time.16 However, others have pointed out that the authors are those who also suggest very high rates of CRPS post injury, thereby ascribing a diagnosis of CRPS to what may be simple post-operative inflammation.

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The authors do go on to show interestingly, however, that the average gap needed in a POP cast to prevent these adverse consequences was determined to be 0.8 cm between the layer of skin and the inside of the POP cast. However, a gap of 0.8 cm is large enough to allow redisplacement of the fracture15 and may result in a worse outcome for the majority of patients. Oedema constrained by too tight a cast can result in adverse consequences such as compartment syndrome and CRPS.17,18,19,20,21 A POP cast that is too tight is the most important risk factor for the development of CRPS, according to Reichert et al.10 and a link between cast tightness and CRPS is suggested in the literature.4,14 According to Reichert et al.: ‘Incorrect immobilising dressing or immobilisation for too long cause venostasis on the periphery, pain and a local inflammatory state.’10 If we simply look at immobilisation by casting, we can see that it can account for the ‘motor and sensory changes that have been the hallmark of CRPS’22 excluding pain. For example, creating a barrier to external environments can account for observed hypersensitivity.22,23 Immobilisation can account for skin temperature changes, swelling, features of a neglect-like state, and clumsy movements with reduced coordination on removal of the cast, to name but a few. The only remaining issue to consider then would be the cause of the pain. It has been suggested that immobilisation is a possible cause of the pain, though this has not been proven with certainty.22 Others studies also claim that a tight POP cast causes algodystrophy, now known as CRPS, but this has not been proven. Field et al. devised a method of measuring cast tightness to establish the association between CRPS-type symptoms and cast tightness.16 It was found that patients with CRPS-type symptoms have consistently tighter casts but this was only significant at one, two and three weeks, but critically the long-term symptology and prognosis was not altered.16 It has been suggested that too tight a cast leads to ischaemia which produces a cascade of inflammatory events leading to swelling of the affected limb.24,25 while CRPS itself is by definition characterised by early oedema.4,26. Field et al. suggested that swelling caused by CRPS led to the cast being excessively tight rather than the converse argument of the cast being applied too tightly leading to the development of CRPS.16 However, a correlation between finger swelling and cast tightness was used to determine whether CRPS caused the swelling, and this method was not definitive in determining the source of the swelling, though it seems more likely given that CRPS can still occur in patients with no cast applied. Therefore, from this study we can see that it is possible to predict which patients will go on to develop CRPS-type symptoms if we measure their cast tightness at two weeks post fracture.16

Conclusion In conclusion, it is clear that post-traumatic swelling and swelling due to excessively tight POP casts may play a significant role in early patient outcome. However, there is currently no evidence that a tight cast leads to CRPS. This is not surprising because it is currently accepted that there is no relationship between the magnitude of the trauma and development of CRPS. Using inflammatory cells as markers of which type of inflammation is present in a tight POP cast could lead us to a better understanding of the effect of a tight POP cast on the aetiology of CRPS. The varying incidences of CRPS seen in different studies are to some extent caused by the lack of a gold standard for CRPS diagnosis, as fundamentally it is still a clinical diagnosis. If we can clarify the guidelines so that there is no longer a grey area as to whether a patient has CRPS or simply normal post-traumatic symptoms caused by disuse,

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immobilisation and the nature of traumatised cells, we can then start to better understand the consequences of having a POP cast on post fracture, and determine whether it can truly lead to harmful consequences in a sizeable percentage of fracture patients. If trauma is considered to be a rare but significant cause of CRPS, perhaps the application of a tight cast might also be considered a ‘trauma’ associated with the development of CRPS. However, attribution is likely to be an issue if the cast was put on as a result of a trauma, which in itself was associated with a distinct but rare possibility of development of CRPS. With the considerable diagnostic uncertainty as to distinguishing early CRPS from post-trauma inflammation and the undoubted exacerbation of CRPS-type symptoms by immobilization, which can occur with any cast application, causally relating CRPS with tight POP application remains controversial. Conflict of interest disclosures

This manuscript is an original article. No funding has been received for this manuscript. There are no conflicts of interest or financial associations to declare. This manuscript has not been presented at any meeting.

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References                                                                                                                       1 De Mos, M., Sturkenboom, M. C., & Huygen, F. J. Current understandings on complex regional pain syndrome. Pain Practice: The Official Journal of World Institute of Pain 2009, 9(2):86– 99. Birklein, F., Kunzel, W., & Sieweke, N. Despite clinical similarities there are significant differences between acute limb trauma and complex regional pain syndrome I (CRPS I). Pain 2001, 93(2):165–171.

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Schwarzer, A. & Maier, C. Complex regional pain syndrome. Chapter 33 in Guide to Pain Management in Low Resource Settings (IASP Press, 2010), A. Kopf & N. Patel (eds.), 249–254.

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Atkins, R. M. Complex regional pain syndrome. The Journal of Bone & Joint Surgery, British Volume 2003, 85(8):1100–1106.

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McBride, A. & Atkins, R. Complex regional pain syndrome. Current Orthopaedics 2005, 19(2):155–165.

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Raja, S. N. & Grabow, T. S. Complex regional pain syndrome I (reflex sympathetic dystrophy). Anesthesiology 2002, 96(5):1254–1260.

6

Goebel, A. Complex regional pain syndrome in adults. Rheumatology (Oxford) October 2011, 50(10):1739–1750.

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Harden, R. N., Bruehl, S., Perez, R. S., Birklein, F., Marinus, J., Maihofner, C., Lubenow, T., Buvanendran, A., Mackey, S., Graciosa, J., Mogilevski, M., Ramsden, C., Chont, M., & Vatine, J. J. Validation of proposed diagnostic criteria (the ‘Budapest Criteria’) for Complex Regional Pain Syndrome. Pain August 2010, 150(2):268–274.

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Reichert, P., Rutowski, R., Greczner, T., Gosk, J., Zimmer, K., & Wnukiewicz, W. The Reasons for and Diagnostics of Algodystrophic Syndrome of the Upper Extremity in Own Material. Advances in Clinical and Experimental Medicine 2007, 16(5):669.

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Butler, S., Nyman, M., & Gordh, T. Immobility in volunteers transiently produces signs and symptoms of complex regional pain syndrome. Progress in Pain Research and Management 2000, 16:657–660.

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Siddiqui, M., Siddiqui, S., Ranasinghe, J., & Furgang, F. Complex Regional Pain Syndrome: A Clinical Review. The Internet Journal of Pain, Symptom Control and Palliative Care 2001, Vol. 2, No. 1. DOI: 10.5580/158b.

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Stoler, J. M. Patients with Ehlers Danlos syndrome and CRPS: a possible association? Oaklander ALPain (July) 2006, 123(1–2):204–209. Epub April 4 2006

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(http://www.ncbi.nlm.nih.gov/pubmed?term=Oaklander%20AL%255BAuthor%255D&cauthor =true&cauthor_uid=16600507). Garcia-Elias, M. & Folgar, M. A. The management of wrist injuries: an international perspective. Injury 2006, 37(11):1049–1056.

14

Love, C. Care of patients sustaining Colles’ fractures: a critical review. Journal of Orthopaedic Nursing 1998, 2(4):185–191.

15

Field, J., Protheroe, D., & Atkins, R. Algodystrophy after Colles fractures is associated with secondary tightness of casts. Journal of Bone & Joint Surgery, British Volume 1994,76(6):901– 905.

16

Boyd, A. S., Benjamin, H. J., & Asplund, C. Principles of casting and splinting. American Family Physician 2009, 79(1):16–22.

17

Halanski, M. & Noonan, K. J. Cast and splint immobilization: complications. The Journal of the American Academy of Orthopaedic Surgeons 2008, 16(1):30–40.

18

Garfin, S. R., Mubarak, S., Evans, K., Hargens, A., & Akeson, W. Quantification of intracompartmental pressure and volume under plaster casts. The Journal of Bone & Joint Surgery, American Volume 1981, 63(3):449.

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Nielsen, D. M. & Ricketts, D. M. Where to split plaster casts. Injury 2005, 36(5):588–589.

Di Domenico, L. A. & Sann, P. Univalve Split Plaster Cast for Postoperative Immobilization in Foot and Ankle Surgery. The Journal of Foot and Ankle Surgery: Official Publication of the American College of Foot and Ankle Surgeons 2012.

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Butler, S. Disuse and CRPS. Progress in Pain Research and Management 2001, 22:141–150.

Ramsey, L. Report of a focus group survey of current practice in the therapeutic treatment of Complex Regional Pain Syndrome in the United Kingdom. Hand Therapy 2008, 13(2):45–53.

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Coderre, T. J., Xanthos, D. N., Francis, L., & Bennett, G. J. Chronic post-ischemia pain (CPIP): a novel animal model of complex regional pain syndrome-type I (CRPS-I; reflex sympathetic dystrophy) produced by prolonged hindpaw ischemia and reperfusion in the rat. Pain 2004, 112(1–2): 94–105.

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Dudko, S., Kusz, D., Wojciechowski, P., & Stoltny, T. Operative treatment of ankles fractures using internal osteosynthesis by a minimal surgical approach. The Foot 2004, 14(4):185–191.

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Doury, P., Dirheimer, Y., Pattin, S., & Villiaumey, J. Algodystrophy: Diagnosis and Therapy of a Frequent Disease of the Locomotor Apparatus (Springer-Verlag, 1981).

26

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Contacts/correspondence Zahra Safarfashandi E-mail: zs1010@imperial.ac.uk

Intellectual property & copyright statement We as the authors of this article retain intellectual property right on the content of this paper. We as the authors of this paper assert and retain legal responsibility for this paper. We fully absolve the Editors and Company of JoOPM of any legal responsibility from the publication of our paper on their website. Copyright 2013. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

63  


Peripheral nerve field stimulation for post-surgical neuropathic pain: correlation between quantitative sensory testing and efficacy two years post implantation Dr Manohar Lal Sharma FRCA FFPMRCA 2 Dr Devjit Srivastava FRCA FFPMRCA 3 Jibril Farah FRCS 4 Mark Draper 5 Dr Manish Gupta FRCA

1

Abstract This report describes the application of peripheral nerve field stimulation (PNFS) to two patients with refractory neuropathic pain, where conventional medical therapy failed. Quantitative sensory testing was done during trial phase and at one year post implantation. Patients initially underwent a trial of PNFS for two weeks with StimuLong monopolar stimulating lead (Pajunk UK Medical Products Ltd) before being implanted with a permanent Pisces Quad plus lead (Model 3888, Medtronic UK]. The PNFS lead was implanted in the left scapular region for post-thoracotomy pain in the first patient, and in the anterior chest wall for post-sternotomy pain in the second patient. Along with patientsâ&#x20AC;&#x2122; self-reported pain scores, quantitative sensory testing (QST) changes with and without stimulation were also observed. There was more than 50% reduction in pain scores in both patients during the trial period, along with objective improvement in QSTs. Bedside QSTs performed at one year showed (similar changes) a significant increase in mechanical detection threshold and mechanical pain threshold, and a decrease in: wind-up ratio, temporal summation pain and area of dynamic allodynia. Pain relief is sustained at two years. The patients were able to return to work and came off all the analgesics. These results demonstrate PNFS as a potential treatment option in medically refractory postsurgical neuropathic pain. Along with long-term self-report of pain relief, this study explores the correlation with bedside QSTs, and the potential for QST to be used as another objective predictor of long-term success for PNFS. The study was limited by small sample size. Keywords Pain, peripheral nerve stimulation, peripheral nerve field stimulation, neuromodulation, neurostimulation, neuropathic pain, quantitative sensory testing (QST)

1

Consultant, pain medicine, Walton Centre NHS Foundation Trust. Consultant, anaesthesia and pain medicine, Raigmore Hospital, Inverness. 3 Consultant neurosurgeon, Walton Centre NHS Foundation Trust. 4 Senior neuromodulation physiotherapist, Walton Centre NHS Foundation Trust. 5 Specialist registrar, pain medicine, Walton Centre NHS Foundation Trust. 2

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Introduction The history of neuromodulation dates back to 1967 when Wall and Sweet inserted an electrode into their own infraorbital foramina.1 Since then, it has expanded to include dorsal column, motor cortex, deep brain and peripheral nerve stimulation.2 Spinal cord stimulation (SCS) is established as a treatment for refractory neuropathic pain.3 Often, pain does not fit within the area sub-served by one or two peripheral nerves, especially in patients with post-surgical neuropathic pain. In these patients, success has been reported using spinal cord stimulator leads placed subcutaneously in the area of pain.4 This has been termed peripheral nerve field stimulation (PNFS). Specifically designed leads have now been awarded the CE mark for this indication. In a nationwide, multicentre retrospective study, the largest study to date utilising PNFS involving 111 patients, Sator-Katzenschlager et al. demonstrated the efficacy of PNFS in chronic non-cancer pain.7 There was a significant reduction of pain scores at three months, along with sustained reduction in analgesic consumption. In a recent study, 100 patients received PNFS for the treatment of chronic craniofacial, thoracic, lumbosacral, abdominal, pelvic and groin pain conditions.19 The authors demonstrated an average pain reduction of 4.2 points on the numeric rating scale following treatment with PNFS. At an average follow-up period of 8.1 months, 72% of patients had reduced analgesic usage. Predictors of good response were focal neuropathic pain (the term focal neuropathic pain is not accepted terminology – suggested option would be localised neuropathic pain), minimal numbness and marked tactile allodynia. We report efficacy of PNFS at two years and quantitative sensory testing (QST) findings at one year for two patients with severe neuropathic pain unrelieved by conventional pharmacological treatment. There are very few studies that demonstrate the relation between efficacy and objective QST findings following PNFS.

Case one X is a 60-year-old woman who was born with spinal muscular atrophy syndrome with scoliosis of thoracic spine, and had been wheelchair-bound since her teens. She underwent multiple scoliosis correction surgeries during her lifetime, the last one being in 2004. Following her last revision surgery, she developed pain in her left posterior chest wall over her scapula (Figure 1). The pain was sharp and stabbing in character. She reported sensitivity to light touch over the painful area. On examination, she had marked tactile and mechanical allodynia over the left scapular area. The pain was rated as 7 out of 10 on the average and 10 out of 10 at worst on the numerical rating scale, and was significantly interfering with general activity, work, sleep and enjoyment of life. She had a poor response to the conventional pharmacological treatment for neuropathic pain – it may be better to mention what pharmacological treatment (can include doses as well) she had. She did not respond to topical application of 5% Lidocaine patches or a trial of TENS.

Methods It was decided to offer her a trial of PNFS following a multidisciplinary team assessment. Under local anaesthetic, a StimuLong monopolar stimulating catheter (Pajunk UK Medical Products Ltd®) shown in Figure 1 was inserted subcutaneously 65

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into the painful area. This was connected to a MultiStim Sensor (Pajunk UK Medical Products Ltd®) pulse generator. The stimulation settings were frequency 2 Hz; amplitude 4–6 mA and pulse width 390 milliseconds. The stimulator was turned on for 15 minutes every four hours. These settings were as recommended by Theodosiadis et al.20 The trial period lasted for two weeks. During the early trial period, there was a more than 50% reduction in pain scores (NRS) and the carry-over effect lasted for about two hours on average. She also reported a marked reduction in tactile allodynia.

Figure 1: Area of brush dynamic allodynia over the left shoulder and trial lead in situ in patient 1. Post stimulation, there was no area left with brush dynamic allodynia.

It was decided to proceed with a permanent implant. The patient had a Pisces Quad Plus (Medtronic, product code 3888-33) lead introduced through a small flank incision and connected through a 51 cm extension lead to a Versitrel Synergy (Medtronic) battery in the anterior abdominal wall on the left side (Figure 2). The stimulation parameters after the permanent implantation were as shown in Table 1, and were adjusted for best coverage, acceptability and comfort by the neuromodulation physiotherapist.

Figure 2: PNFS lead in patient 1

We performed QST at one year after implantation. The tests were based on the guidelines on QST by the German Research Network on Neuropathic Pain and our institutional guidelines for QST. The aim was to observe changes in the QSTs, with and without stimulation. We followed a modified bedside version of the German Research Network on Neuropathic Pain (DFNS) protocol.8 This was a modified bedside QST, which excluded the Peltier electrode heat testing. The aim was to apply

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a simple reproducible bedside QST protocol within the time limits of clinical routine. We tested for mechanical detection threshold, mechanical pain threshold, temporal summation with calculation of wind-up ratio (using von Frey hair) and area of dynamic allodynia using a brush. QST was done with the patient resting in a comfortable semi-reclining position. The control or reference area was selected contra-lateral to the pain area on the back (over the right scapula). The patient kept the stimulator off for 12 hours and one set of observations was done at this point. The stimulator was switched on. After half an hour, another set of QST was recorded. The von Frey monofilament (Sense lab Aesthesiometer; Somedic AB, Sweden) was used to quantify detection and punctate pain thresholds. Detection threshold is the smallest von Frey fibre size at which touch is perceived, whereas the punctate pain threshold is the smallest size of von Frey hair necessary for the patient to feel pain, which is a change of > 2 on the NRS from baseline pain. Ascending and decreasing thresholds were tested on both a control site and the area of neuropathic pain. There was a gap of three minutes before the next test. Dynamic allodynia was recorded using a soft brush. Five strokes of a soft brush at 1, 4, 7, 10 and 12 o’clock positions were used. The von Frey monofilament at which pain threshold was detected was used for temporal summation. Five blocks of ten stimulations at 2 Hz were performed with pain scores before and after each block. The wind-up ratio was calculated using the mean rating of the temporal summation score series divided by the rating of a single stimulus NRS score. Stimulation parameters Frequency (Hz) Pulse width (milliseconds) Current (volts)

Trial After implant 2 10 100 450 3.9 4.5

At 18 months follow-up 40 450 4.5

Table 1: Stimulation parameters for PNFS in patient 1

Results The QST results at one year are shown in Table 2. This patient’s mechanical detection threshold increased from 8 to 11 g/mm2. Punctate pain threshold increased from 8 to 122 mm2 in the painful area. There was a decrease in area of dynamic allodynia from 365 to 0 cm2 (Table 2). Temporal summation pain score was 10 out of 10 at baseline and decreased to 0 out of 10 following stimulation. The wind-up ratio decreased from 1.5 (pre stimulation) to 0 (post stimulation). Two years later, the device settings remain unchanged and the patient is off all analgesics. She reports good pain relief and has resumed work as a teacher. The device is used for about 15 minutes every 3–4 hours during the day. Table 2: QST results in the neuropathic pain area in patient 1 at one year post PNFS implant.

von Frey detection 67

Affected area Off stim During active stim 8 11

Unaffected area Off stim During active stim 11 11

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threshold g/cm2 Punctate pain threshold g/cm2 Temporal summation (NRS pain score) at end of block 5 Area of dynamic allodynia Wind-up ratio

8

122

53

53

10/10

6/10

2/10

1/10

365 cm2

0 cm2

1.5

0

1.5

1.5

Case two W is a 39-year-old man who developed neuropathic pain in his anterior chest wall after having undergone aortic valve replacement surgery in 2005. His chest pain started after the wound had healed (Figure 3). He described his pain as a constant burning sensation made worse by light touch. His NRS was 7–8 out of 10 on average. Conventional pharmacological treatments for neuropathic pain – local anaesthetic and steroid injections – and TENS were all unsuccessful.

Methods After multidisciplinary team assessment, the patient underwent a trial of PNFS using a similar technique and equipment as in case one. The patient reported a significant reduction in pain scores to 2–3 out of 10, and the effect lasted for approximately 30 minutes initially and increased to 1.5 hours by day three of the trial. He subsequently underwent permanent implantation of PNFS leads in December 2009 (Figure 4). Lead settings were 1– 3+ (left) pulse width (pw) 360 milliseconds, frequency 10 and amplitude 7.5 V with 2– 3+ (right lead) pw 360 milliseconds.

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Figure 4: PNFS leads in patient 2

Results Following permanent implantation, his pain scores remain at 2 out of 10 on the NRS. His QST data at one year is shown in Table 3. On QST: mechanical detection and punctate pain threshold increased. There was a modest decrease in NRS scores on temporal summation and significant decrease in the area of brush allodynia. Three months post implantation, he had returned to work as a painter and decorator. He uses his stimulator for 15 minutes every three hours during the day. Two years post implantation, he continues to be off all analgesics and at work. Figure 3: Area of dynamic brush allodynia (blue circle). The area of allodynia receded to a smaller area (green circle) post stimulation.

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Table 3: QST results in the neuropathic pain area in patient 2 at one year post PNFS implant

von Frey detection threshold g cm2 Punctate pain threshold g/cm2 Temporal summation (NRS pain score) at end of block 5 Area of dynamic allodynia Wind-up ratio

Affected area Off stim During active stim 8 90

Unaffected area Off stim During active stim 5 5

38

133

49

90

6/10

4/10

5/10

3/10

562 cm2

182 cm2

2.2

1.5

Discussion We report both the efficacy and objective bedside QST findings of PNFS in two consecutive patients. The study published by Verills et al. reported significant reduction in pain scores, disability and analgesic use in 100 patients.19 Our report attempts to further endorse the efficacy of PNFS by combining the objectivity of bedside QST. We decided to perform bedside QST on both patients at one year post implant. These tests were performed during the trial phase of PNFS and matched patients’ self-report of pain relief. Clinical examination for neuropathic pain usually reveals positive and negative sensory phenomena.15 QST is a psychophysical test which tests sensory perception during the administration of stimuli with predetermined physical properties and following a set protocol.8 A physical stimulus like touch or pressure activates a specific set of receptors which generate nerve action potentials in specific anatomical components of the sensory nervous system, which is then transmitted via the central pathways to the thalamus and then to the cortical structures relevant to perception and assignment of emotional attributes. When there is neuropathic pain, there are sensory deficits and positive sensory phenomena attributable to dysfunction of small nerve fibres (Aδ & C) and this can be picked up by QSTs.16 There are limitations with QSTs as the results may be affected by the subjective nature of a patient’s reporting and an operator’s experience and influence. This is in contrast to nerve conduction studies, which pick up negative sensory phenomena/deficits caused by large myelinated nerve fibres. The exact mechanism of action of PNFS is not known. PNFS delivers electrical stimulation via subcutaneously placed electrodes. It is efficacious at both low (2– 10 Hz) and high frequencies, and postulated mechanisms of action could involve anterograde activation of Aβ and Aδ in the preferred order fibres. Low-frequency stimulation of these fibres causes long-term depression (LTD) of mono- as well as polysynaptic excitatory post-synaptic potentials (EPSP) in substantia gelatinosa neurons lasting up to several hours.11 This was borne out in our patients where using the stimulator for 15 minutes had a carry-over effect of more than two hours, even during the initial trial phase.

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Both patients reported long-term efficacy with PNFS, with significant decrease in their pain scores – the effects persisting at two-year follow-up. The evidence for efficacy was bolstered by coming off all analgesics in both patients. Often, the ability of the patient to come off medications is used as a measure of efficacy of neuromodulation.14 We decided to perform QST on both patients at baseline (trial phase) and one year post implant. Although baseline QST data at trial phase is not included in this report, it showed similar results. The other reason for non-inclusion of trial QST is because the protocol used for QST was different, but it matched patients’ self-report of pain relief. Our rationale behind performing QST at one year was to observe whether there were any consistent and objective changes in QSTs in the neuropathic pain area pre and post stimulation. Herein lies the potential for QST to be used as another objective predictor of success for PNFS if consistent changes are found before and after therapy, correlating with patients’ pain scores. Our QST included: (a) mechanical detection threshold using von Frey hair – this is likely to activate low-threshold mechanoreceptors (LTM) in the skin (this technique has been used to screen for small-fibre neuropathy in diabetics); (b) dynamic allodynia with the brush, which would also involve activation of LTM; and (c) punctate or mechanical pain threshold, which would involve activation of high-threshold mechanoreceptors.16 To interpret the impact of PNFS on QSTs, findings prior to active stimulation need to be known, and to observe if there are any differences between the unaffected (control) area and the affected (neuropathic pain) area. (A) QST changes in area of neuropathic pain when off stimulation at one year We observed that for von Frey mechanical detection threshold in patient 1, there was sensory gain (decreased threshold), whereas in patient 2 there was sensory loss (increased threshold) (Table 2 and 3). In the DFNS study,8 the sensory abnormalities of 1,236 patients with neuropathic pain were studied. They reported that across the spectrum of neuropathic pain, roughly 30% of the patients exhibited sensory loss (as in patient 2). In the same study, there are 15% of patients who have been detected to have sensory gain (as in our patient 1). This mix of increased/decreased mechanical threshold was also reported by Werner and Kehlet (2010) in patients with persistent neuropathic pain following herniotomy.17 For punctate pain thresholds, there was a decrease in thresholds in both patients suggesting hyperalgesia. The DFNS study8 reports that for nociceptive parameter testing, sensory gain (hyperalgesia) was frequent (7.5–26.3%) but sensory loss was also seen in 0.3–12.85% of patients. Both our patients were detected to have sensory gain and that fits in with the report of the DFNS study. Additionally, Rasche et al. (2006) performed QST studies in SCS patients and reported a decrease in mechanical threshold in their patients with chronic unilateral radicular leg pain.18 These results seem to suggest that neuropathic pain patients are more likely to present with decreased mechanical thresholds on QST when off stimulation. (B) QST changes during active stimulation at one year post permanent implant A dramatic result during active stimulation was the reduction in the area of brush allodynia along with significant reduction in temporal summation pain scores during 71

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active stimulation (Table 2 and 3). Temporal summation indicates central sensitisation and changes with PNFS would indicate modulation of these central changes. Our results seem to indicate as if PNFS has an anaesthetic effect (elevation of detection and punctate threshold during active stimulation). This is not seen in other forms of stimulation. This needs further exploration as the mechanism of action of PNFS may differ from that of SCS. This phenomenon needs to be studied with a larger group of patients. Based on our results, we cannot suggest a pattern of QSTs reflecting efficacy with PNFS. We would like to suggest studying this with a larger series evaluating QST during trial PNFS stimulation and ascertaining whether QST changes after PNFS are indeed different from those after SCS.

Conclusions We report two patients with refractory post-surgical neuropathic pain where PNFS demonstrated long-term efficacy and improvement in function. There were reversible QST changes seen with active stimulation but no consistent pattern could be described. This could be due to small sample size, phenotypic variations in pain mechanisms, the psychophysical nature of QSTs or different mechanism of efficacy of PNFS. Utilising QSTs along with other measures of efficacy of PNFS may have advantages to improve patient selection for PNFS. This, though, still needs to be studied in a larger number of patients, before implementing in routine practice.

Acknowledgements

None

Conflict of interest disclosures

None

References 1 Wall, P. D., & Sweet, W. H. Temporary abolition of pain in man. Science 1967, 155(758):108–109. 2 Stuart, R. M., & Winfree, C. J. Neurostimulation techniques for painful peripheral nerve disorders. Neurosurg Clin N

Am 2009, 20(1):111–120, vii–viii. 3 National Institute of Clinical Excellence, United Kingdom. Spinal cord stimulation for chronic pain of neuropathic or

ischemic origin. NICE technology appraisal guidance 159. 2008: 20 April 2011.Available online at http://www.nice.org.uk/nicemedia/pdf/TA159Guidance.pdf. 4 Goroszeniuk, T., Kothari, S., & Hamann, W. Subcutaneous neuromodulating implant targeted at the site of pain.

Reg Anesth Pain Med 2006, 31(2):168–171. 5 Alo, K. M., & Holsheimer, J. New trends in neuromodulation for the management of neuropathic pain. Neurosurgery

2002, 50(4):690–703; discussion 703–704. 6 Kothari, S. Neuromodulatory approaches to chronic pelvic pain and coccygodynia. Acta Neurochir Suppl 2007,

97(1):365–371. 7 Sator-Katzenschlager, S., Fiala, K., Kress, H. G., Kofler, A., Neuhold, J., Kloimstein, H., Ilias, W., Mozes-Balla, E.

M., Pinter, M., Loining, N., Fuchs, W., Heinze, G., & Likar, R. Subcutaneous target stimulation (STS) in chronic noncancer pain: a nationwide retrospective study. Pain Pract 2010, 10(4):279–286. 8 Rolke, R., Baron, R., Maier, C., Tölle, T. R., Treede, R. D., Beyer, A., Binder, A., Birbaumer, N., Birklein, F., Bötefür,

I. C., Braune, S., Flor, H., Huge, V., Klug, R., Landwehrmeyer, G. B., Magerl, W., Maihöfner, C., Rolko, C., Schaub, C., Scherens, A., Sprenger, T., Valet, M., & Wasserka, B. Quantitative sensory testing in the German Research Network on Neuropathic Pain (DFNS): standardized protocol and reference values. Pain 2006, 123(3):231–243. 9 Goroszeniuk, T. Short neuromodulation trial in neuropathic pain produces varying duration but reproducible pain

relief. Proceedings of the 4th congress of EFIC, 2–6 September 2003, 326.

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10 Krames, E. S., & Abejon, D. Peripheral nerve stimulation or is it peripheral subcutaneous stimulation; what is in a

moniker? Neuromodulation 2009, 12(1):1–4. 11 Randic, M., Jiang, M. C., Cerne, R. Long-term potentiation and long-term depression of primary afferent

neurotransmission in the rat spinal cord. J Neurosci 1993, 13(12):5228–5241. 12 Kehlet, H., & Rathmell, J. P. Persistent postsurgical pain: the path forward through better design of clinical studies.

Anesthesiology 2010, 112(3):514–515. 13 Wong, G. T., Yuen, V. M., Chow, B. F., & Irwin, M. G. Persistent pain in patients following scoliosis surgery. Eur

Spine J 2007, 16(10):1551–1556. 14 Peters, K. M., & Konstandt, D. Sacral neuromodulation decreases narcotic requirements in refractory interstitial

cystitis. BJU International 2004, 93(6):777–779. 15 Haanpää, M., Attal, N., Backonja, M., Baron, R., Bennett, M., Bouhassira, D., Cruccu, G., Hansson, P.,

Haythornthwaite, J., Domenico, G., Jensen, T., Kauppilam, T., Nurmikko, T., Rice, A., Rowbotham, M., Serra, J., Sommer, C., Smith, B., & Treede, R. NeuPSIG guidelines on neuropathic pain assessment. Pain 2011, 152:14–27. 16 Hansson, P., Backonja, M., & Bouhassira, D. Usefulness and limitations of quantitative sensory testing: clinical

and research application in neuropathic pain states. Pain June 2007, 129(3):256–259. 17 Werner, M., & Kehlet, H. Characterization of persistent postoperative pain by quantitative sensory testing.

European Journal of Pain Supplements (serial online) 2010, 4(4):203. 18 Rasche, D., Ruppolt, M., Kress, B., Unterberg, A., & Tronnier, V. Quantitative sensory testing in patients with

chronic unilateral radicular neuropathic pain and active spinal cord stimulation. Neuromodulation (serial online) 2006, 9(3):239–247. 19 Verrills, P., Vivian, D., Mitchell, B., & Barnard, A. Peripheral nerve field stimulation for chronic pain: 100 cases and

review of the literature. Pain Medicine 2011, (12):1395–1405. 20 Theodosiadis, P., Samoladas, E., Grosomanidis, V., Goroszeniuk, T., & Kothari, S. A case of successful treatment

of neuropathic pain after a scapular fracture using subcutaneous targeted neuromodulation. Neuromodulation 2008, 11(1):62–65.

Contacts/correspondence Dr Manohar L. Sharma, Consultant Pain Medicine, Walton Centre NHS Foundation Trust, L9 7LJ E-mail: manoharpain@yahoo.co.uk

Intellectual property & copyright statement We as the authors of this article retain intellectual property right on the content of this paper. We as the authors of this paper assert and retain legal responsibility for this paper. We fully absolve the Editors and Company of JoOPM of any legal responsibility from the publication of our paper on their website. Copyright 2013. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Sciatic nerve palsy following sacroiliac joint injection Dr Catherine Gwilt MBBS BSc (Hons) MRCP(UK) 2 Dr Neil Collighan FRCA FFPMRCA

1

Abstract Sacroiliac joint injections are a therapeutic intervention for chronic lower-back pain. Here, we report a sciatic nerve palsy resulting in unilateral leg weakness, as a complication of a routine sacroiliac joint injection. The likely aetiology was perineural pooling of local anaesthetic due to extra-articular needle placement. Leg weakness spontaneously resolved as local anaesthetic was reabsorbed. No other reports of this complication were identified in the literature. We conclude that clinicians should be aware of this rare but notable complication of a commonly performed procedure indicated for chronic pain. Keywords Sacroiliac, joint, injection, complication, sciatic, nerve, palsy, paralysis, chronic, lower, back, pain

Introduction Lower-back pain originating from the sacroiliac joint (SIJ) may be amenable to direct injection of local anaesthetic and steroid into the joint. This procedure provides symptomatic relief and is considered low risk, usually being performed as a day case. Here, we report a complication of a SIJ injection. This case was originally discussed and presented in an online educational forum for pain specialists.

Case A routine SIJ injection for relief of chronic lower-back pain was performed on an unsedated patient in the prone position with fluoroscopic guidance and 10° of oblique tilt on the C-arm. The needle was placed in the inferior third of the right SIJ. Intravenous contrast was not used but radiographs confirmed needle placement. 2 ml of 0.25% bupivacaine with 40 mg triamcinolone were injected over 30 seconds with minimal discomfort. Within minutes, a dense sciatic nerve palsy developed in the right leg causing unilateral flaccid paralysis. There was no back pain and the contralateral leg and sphincters were unaffected. The patient was admitted to hospital for investigation of persistent weakness. Magnetic resonance imaging (MRI) of spine and pelvis were unremarkable. Electromyography (EMG) and nerve conduction studies were not performed due to limited utility in the acute period. The correct substances were injected and drug errors, such as a mistaken injection of phenol, excluded. The leg weakness spontaneously resolved over approximately five days requiring no further intervention. The patient had no residual neurological deficit.

1 2

Specialist Trainee in Palliative Medicine, Pilgrims Hospice Thanet, Margate, Kent, UK. Consultant in Anaesthesia and Pain Management, East Kent Hospitals, UK. Journal of Observational Pain Medicine â&#x20AC;&#x201C; Volume 1, Number 2 (2013) ISSN 2047-0800


Literature search methods A separate literature search was performed after the case had been discussed. Sources included the Cochrane database,1 the National Institute of Clinical Excellence (NICE) website,2 the National Patient Safety Agency (NPSA) website,3 the Palliative Medicine Bulletin Board4 (an online forum for the international palliative care community), Medscape5 (an online health-care resource featuring peer-reviewed articles) and the health-care database EMBASE.6 Key search terms are listed in Appendix 1. English language and human studies were set as limits. No year limit was set. Relevant literature identified included one Cochrane review, one NICE guideline and 84 original publications. There were no relevant findings on the NPSA website and Palliative Medicine Bulletin Board.

Discussion This case describes spontaneously resolving sciatic nerve palsy after sacroiliac joint injection. This is an unexpected complication of a low-risk procedure. Descriptions of complications in the literature are rare. There were no adverse outcomes reported in a case series of ten patients receiving a total of 13 corticosteroid SIJ injections.7 Recognised unwanted sequelae of joint injections do include peripheral nerve lesions but other complications such as infection are more common.8 No case reports of sciatic nerve palsy following SIJ injection were identified in the literature. A recent Cochrane review on joint injections for lower-back pain9 and a NICE guideline on the management of lower-back pain10 did not comment on SIJ injections. Possible explanations for unilateral leg weakness following SIJ injection are:

1) Cord damage This is unlikely as the contralateral leg was unaffected and bladder and bowel function were normal.

2) Direct injection into sciatic nerve Again, this is unlikely as direct nerve injection is associated with severe pain. This joint injection was associated with only unremarkable, minimal discomfort.

3) Direct injection into branches of inferior gluteal artery The inferior gluteal artery lies medial to the sciatic nerve and, while anatomically variable, it can supply the sciatic nerve.11 Nerve ischaemia from inadvertent injection into the inferior gluteal artery could account for a sciatic nerve palsy. Ischaemia is unlikely in this case though as the neurological defect resolved over days. Complete nerve regeneration would take longer than this time frame. For example, one case report of an ischaemic sciatic nerve palsy complicating a sciatic nerve block took more than a year to resolve.12

4) Injection into S2/S3 foramen A peripheral nerve foramen may have inadvertently been injected, causing damage to the nerve roots which contribute to the sciatic nerve (Figure 1). However, as the sciatic nerve is comprised of L4-S3 nerve roots, injury to an isolated nerve root would be more likely to cause a radicular deficit rather than a peripheral nerve palsy.

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Figure 1 – Diagrammatic view of the posterior hemi-pelvis and spine, demonstrating the close anatomical location of the sciatic nerve to the sacroiliac joint

5) Prolonged effects of local anaesthetic The most likely mechanism of nerve damage was injection of local anaesthetic into the sciatic nerve sheath. The nerve block was probably prolonged due to perineural local anaesthetic pooling. Due to the proximity of the sciatic nerve to the SIJ (Figure 1), it would have been possible to pass through the SIJ and place the needle tip directly into the sciatic nerve sheath. The small volumes of steroid and local anaesthetic could have been accommodated within the nerve sheath without pain from pressure effects. The consequent nerve block would be prolonged by perineural pooling of local anaesthetic, but resolved over days as the local anaesthetic reabsorbed. Accurate needle placement into the SIJ by experienced clinicians without fluoroscopic guidance is only 12%.13 While fluoroscopic guidance was, indeed, used to confirm needle placement in the above case, it is still conceivable that extra-articular needle placement could have occurred. Intravenous contrast can be used to help confirm needle placement but benefits must be considered in light of the potential harm – the risk of a contrast reaction is approximately 15%.14 Other risks include contrast-induced nephropathy and drug interactions (e.g. metformin). The use of intravenous contrast remains contentious and it is not the practice of all units or clinicians to use it for low-risk procedures such as SIJ injections. Sciatic nerve palsy due to perineural pooling of local anaesthetic is a diagnosis of exclusion, considered in the presence of normal imaging. While rarer than other complications of a SIJ injection, it is an important differential, as management should be supportive and spontaneous recovery expected.

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Summary We report a sciatic nerve palsy as a complication of a routine sacroiliac joint injection performed with fluoroscopic guidance. Extra-articular injection into the nerve sheath is likely to have caused prolongation of local anaesthetic effects due to perineural pooling of anaesthetic. With reabsorption of local anaesthetic over a period of days, neurological function spontaneously recovered. This complication is rare and not well recognised in the literature. In the presence of reassuring imaging, watchful waiting and supportive therapy may be an appropriate approach to the management of sciatic nerve palsy after routine SIJ injection. Conflict of interest disclosures

CG and NC have no conflicts of interest

Appendix 1 Key search terms used for the literature review were: ‘Sacroiliac’ ‘Injection’ ‘Complication’ ‘Sciatic nerve’ ‘Sciatic nerve palsy’ ‘Direct injection’ ‘Inferior gluteal artery’ ‘Paralysis’ ‘Prolonged nerve block’

References www.cochrane.org. Last viewed 5 March 2012. www.nice.org.uk. Last viewed 5 March 2012. 3 www.npsa.nhs.uk. Last viewed 5 March 2012. 4 www.palliativedrugs.com/bulletin-board-introduction.html. Last viewed 5 March 2012. 5 www.medscape.com. Last viewed 5 March 2012. 6 www.embase.com. Last viewed 5 March 2012. 7 Maugars, Y., Mathis, C., Berthelot, J.-M., Charlier, C., & Prost, A. Assessment of the efficacy of sacroiliac corticosteroid injections in spondylarthropathies: A double-blind study. British Journal of Rheumatology 1996, 35(8):767–770. 8 Cheng, J., & Abdi, S. Complications of joint, tendon, and muscle injections. Techniques in Regional Anesthesia and Pain Management 2007, 11(3):141–147. 9 Staal, J. B., de Bie, R., de Vet, H. C. W., Hildebrandt, J., & Nelemans, P. Injection therapy for subacute and chronic lower back pain. Cochrane Database Syst Rev 16 July 2008, (3):CD001824. 10 Savigny, P., Kuntze, S., Watson, P., Underwood, M., Ritchie, G., Cotterell, M., Hill, D., Browne, N., Buchanan, E., Coffey, P., Dixon, P., Drummond, C., Flanagan, M., Greenough, C., Griffiths, M., Halliday-Bell, J., Hettinga, D., Vogel, S., & Walsh, D. Low back pain: early management of persistent non-specific low back pain. London: National Collaborating Centre for Primary Care and Royal College of General Practitioners, 2009. 11 Georgakis, E., & Soames, R. Arterial supply to the sciatic nerve in the gluteal region. Clinical Anatomy 2008, 21(1):62–65. 12 Bonner, S. M., & Pridie, A. K. Sciatic nerve palsy following uneventful sciatic nerve block. Anaesthesia 1997, 52(12):1205–1207. 13 Hansen, H. C. Is fluoroscopy necessary for sacroiliac joint injections? Pain Physician 2003, 6(2):155–158. 1

2

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http://emedicine.medscape.com/article/422855-overview#aw2aab6b5. Last viewed 5 March 2012.

14

Correspondence Dr Catherine Gwilt, Pilgrims Hospice Thanet, Ramsgate Road, Margate, CT9 4AD E-mail: catherine.gwilt@doctors.net.uk

Intellectual property & copyright statement We as the authors of this article retain intellectual property right on the content of this paper. We as the authors of this paper assert and retain legal responsibility for this paper. We fully absolve the Editors and Company of JoOPM of any legal responsibility from the publication of our paper on their website. Copyright 2013. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Ophthalmic post-herpetic neuralgia Dr Sophie M. Shotter MB ChB BSc, Tunbridge Wells Hospital, Kent Dr Neil Collighan FRCA FFPMRCA, Consultant in Anaesthesia and Pain Management, East Kent Hospitals

Abstract This is a case of chronic ophthalmic post-herpetic neuralgia, which proved very difficult to manage. Many different treatment modalities were suggested, from systemic and topical pharmacological therapies to electrical stimulation and ganglion blocks. Keywords Chronic, ophthalmic, post-herpetic, neuropathic, pain, capsaicin, amitriptyline cream, spheno-palatine, stellate, percutaneous, subcutaneous, electrical, stimulation

Problem An 80-year-old woman with unilateral ophthalmic post-herpetic neuralgia, with radiation to the top of the forehead. The pain had been present for two years without substantial relief. Significant past medical history included insertion of a pacemaker for a rhythm disturbance. Her functional level was good and there was no evidence of cognitive impairment, and a supportive husband at home.

Recommended treatments Pharmacotherapy Pharmacological treatment should follow the Neuropathic Pain Analgesic Ladder, with regular paracetamol followed by the addition of a tricyclic antidepressant and finally an anti-convulsant. Opioid analgesia can also be used with good effect in neuropathic pain, and there is evidence they are beneficial in intermediate-term studies. Tramadol,1 buprenorphine2 and meptazinol are all suggested as useful drugs. The use of partial mu agonists decreases the risk of opioid dependence. Buprenorphine patches are a favoured method of administration because they can be changed on a weekly basis by a relative. Caution must be used when dosing opioids for the elderly population. Sublingual ketamine may be useful as a further alternative way of modulating pain pathways.3 Many topical therapies may provide benefit, although they may have relatively less success in the ophthalmic distribution because of its sensory supply to the cornea and conjunctiva, which means topical therapies may provide incomplete coverage. The use of local anaesthetic, either in patch form or as injections is suggested. Capsaicin cream and patches have also been widely used to treat post-herpetic neuralgia in other distributions.4 Particular caution needs to be exercised using capsaicin cream near the eye. Furthermore, capsaicin patches are not currently licensed for us above Journal of Observational Pain Medicine â&#x20AC;&#x201C; Volume 1, Number 2 (2013) ISSN 2047-0800


the neck. Amitriptyline and gabapentin are also available as creams and may provide relief. There are published case reports of the use of amitriptyline cream of concentrations between 2.5 and 10% with good effect in neuropathic pain syndromes;5 however, there is no evidence for its use in the head and neck area to date.

Therapeutic interventions The therapeutic use of acupuncture is widely underestimated. Although it was attempted unsuccessfully in this patient, it may provide benefit to other similar patients. Facial transcutaneous electrical nerve stimulation (TENS), percutaneous electrical nerve stimulation (PENS) and somatic electrical nerve stimulation (SENS) are all proposed as possible treatment approaches, with some practitioners having achieved good effect in trigeminal neuralgia patients. TENS provides a non-invasive option.6 PENS is minimally invasive and can be used by placing the probe in the deep temporo-zygomatic region parallel to the bone, stimulating the spheno-palatine ganglion. Better effects are reported in patients who do not have marked numbness in the affected area, and in those patients in whom motor stimulation is achieved. The effect can be variable, lasting between three and eight weeks with longer durations following repeat procedures. A potential problem with the patient in this case arises from electrical interference with the implanted pacemaker, and it is suggested that this should be discussed with the equipment manufacturers. All such procedures should be performed in a theatre environment with monitoring and resuscitation equipment available. Stellate ganglion and sphenopalatine blocks are also suggested as potential therapeutic interventions. A review of available literature seems to suggest that early stellate ganglion block is useful in the potential prevention of post-herpetic neuralgia but does not discuss a role in the management of chronic pain situations.7,8 While attempting pharmacological and therapeutic interventions, it is crucial to remember to provide psychological support. Reassurance, literature about postherpetic neuralgia and – if indicated – cognitive behavioural therapy may all help to modify the patient’s behaviour and expectations, and to make the condition more manageable.

Referring consultant feedback Most of the treatment modalities were mentioned. Stellate ganglion block was not attempted due to her pacemaker. The consultant referred this patient to a different hospital for PENS treatment.

References Saxena, A. K., Nasare, N., & Jain, S. et al. A randomised, prospective study of efficacy and safety of oral tramadol in the management of post-herpetic neuralgia in patients from north India. Pain Pract August 2012 [Epub ahead of print]. 2 Pergolizzi, J., Aloisi, A., & Dahan, A. et al. Current knowledge of buprenorphine and its unique pharmacological profile. Pain Pract September–October 2010, 10(5):428– 450. 3 Chong, C., Schug, S. A., Page-Sharp, M., Jenkins, B., & Ilett, K. F. Development of a sublingual/oral formulation of ketamine for use in neuropathic pain: preliminary findings from a three-way randomized, cross-over study. Clin Drug Investig. 2009, 29(5):317–324. 1

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4 Sayanlar,

J., Guleyupoglu, N., Portenoy, R., & Ashina, S. Trigeminal postherpetic neuralgia responsive to treatment with capsaicin 8% topical patch: a case report. J Headache Pain October 2012, 13(7):587–589. 5 Kospky, D. J., & Hesselink, J. M. High doses of topical amitriptyline in neuropathic pain: two cases and literature review. Pain Pract February 2012, 12(2):148–153. 6 Yameen, F., Shahbaz, N. N., Hasan, Y., Fauz, R., & Abdullah, M. Efficacy of transcutaneous nerve stimulation and its different modes in patients with trigeminal neuralgia. J Pak Med Assoc May 2011, 61(5):437–439. 7 Currey, T. A., & Dalsania, J. Treatment for herpes zoster ophthalmicus: stellate ganglion block as a treatment for acute pain and prevention of postherpetic neuralgia. Ann Ophthalmol May 1991, 23(5):188–189. 8 Makharita, M. Y., Amr, Y. M., & El-Bayoumy, Y. Effect of early stellate ganglion block for facial pain from acute herpes zoster and incidence of postherpetic neuralgia. Pain Physician November–December 2012, 15(6):467–474.

Contacts/correspondence Dr Sophie Shotter: smshotter@doctors.org.uk

Intellectual property & copyright statement We as the authors of this article retain intellectual property right on the content of this paper. We as the authors of this paper assert and retain legal responsibility for this paper. We fully absolve the Editors and Company of JoOPM of any legal responsibility from the publication of our paper on their website. Copyright 2013. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Joopm Vol1 Ed 2 (2013)  

This Journal has been created in recognition of the fact that not all information or advances in pain medicine can be presented in a randomi...

Joopm Vol1 Ed 2 (2013)  

This Journal has been created in recognition of the fact that not all information or advances in pain medicine can be presented in a randomi...