Concussion and chronic headache disorders Sports-‐related concussion has gained increasing attention and a welcomed growing awareness amongst the sports medicine community in recent years. Contact sports have a higher incidence of concussion due to their nature and inherent risks. This places players in many vulnerable situations for a variety of head injuries including abrasions, contusions, lacerations, fractures, intra-‐cerebral trauma and concussions. Concussion is defined as a trauma induced alteration in mental status caused by a direct or transmitted force. It has a rapid onset with a short-‐lived impairment of neurological function and contrary to a commonly held belief, may present with or without a loss of consciousness. It is a functional disturbance, but is likely to have both structural and chemical changes, which are presently not detectable by conventional neuro-‐imaging techniques. Post-‐traumatic headache is the most common post-‐concussive symptom and the most frequent type of post-‐traumatic pain associated with mild traumatic brain injury. It often forms part of a post-‐ concussion syndrome encompassing a variety of somatic and psycho-‐behavioral symptoms (dizziness, drowsiness, changes in sleep patterns, behavioral or mood changes, and difficulty with memory, concentration, attention, and thinking.) In the majority of patients, the post-‐concussion syndrome is self-‐limiting with the post-‐traumatic headache and accompanying symptoms gradually improving and spontaneously resolving over a period of weeks. However, in a minority of patients, it may become chronic and persistent, requiring a comprehensive and multidimensional management approach including pharmacologic intervention, physical rehabilitation, and cognitive-‐behavioral therapy. Concussion may precipitate the onset of headaches, exacerbate pre-‐existing headaches or trigger the first attack in susceptible individuals. Patients with a strong family history of migraines may be at an increased risk for developing these chronic headaches. Interestingly, post-‐concussive headaches appear to be more strongly associated with relatively milder initial injuries. The reasons for this association are uncertain. The headache in post-‐concussive states usually occurs within a day of the injury, but may be delayed for weeks and continue for months post injury. The post-‐concussive headache typically presents similarly to one of the primary non-‐traumatic headache disorders: tension-‐type, migraine-‐like, cluster-‐like or mixed headache syndromes. Controversies still exist as to the exact etiology and underlying patho-‐physiology of post-‐concussive headaches. Current hypotheses suggest shared common pathways with primary headache disorders relating to neuro-‐chemical dysfunction and dys-‐regulation, neuronal disturbances and peripheral cervical pain pathways. The threshold for symptoms to present is thought to be lowered with recurrent and multiple concussive episodes, which in turn may lead to cumulative damage presenting with long-‐term consequences (permanent neuro-‐cognitive deficits, depression, memory loss, Alzheimer’s). The trigeminal-‐vascular system may be activated, injured, or disturbed by non-‐penetrating, mild traumatic brain injury. When triggered, the meningeal arteries dilate, which stimulates the peri-‐ vascular sensory trigeminal nerves. Stimulation of the trigeminal nerves results in the release of inflammatory chemicals, which in turn produces further meningeal artery dilation and also activation of the pain generator in the lower brainstem and upper cervical cord (C1-‐C3 cervical segments connect to the trigeminal vascular nucleus). Accompanying the post-‐concussive headache is the very frequent presence of neck pain or occipital neuralgia type pain, which either can exacerbate or be the source of the symptoms. This may be secondary to soft tissue damage (ligaments and muscles), but may involve intervertebral disc
damage and, occasionally nerve root compression. Trigger points and accompanying muscle spasm are frequently found in the trapezium, posterior cervical, and occipital areas. There is scant literature with which to select treatment for post-‐concussive headaches and consequently treatments are based on those strategies prescribed for similar but etiologically distinct headache disorders. A multidisciplinary approach is required in the treatment of post-‐concussive headaches and combining both “central” and “peripheral” interventions has become the most effective therapeutic modality. Abortive and preventative medication, NSAIDs and muscle relaxants, physiotherapy, chiropractic care, relaxation techniques, acupuncture and biofeedback are all available options but treatment should be individualized and tailored towards managing all the presenting symptoms. Patients also require education, support, and counseling to facilitate a sense of involvement in the management of their post-‐concussive headache as well as a sense of control over them. Reasonable expectations should be explained to avoid frustrating therapeutic limitations. Reassurance that this condition will improve is important, as symptoms in the majority of cases progressively lessen over time. Psychotherapy may be needed to facilitate the process of adjusting to (or coping with) chronic post-‐concussive headaches. Delayed recovery or persistent post-‐concussive headaches may result from inadequate or ineffective treatment, overuse of analgesic medications resulting in analgesia rebound phenomena, or co-‐ morbid medical or psychiatric disorders (post-‐traumatic stress disorder, insomnia, substance abuse, depression, or anxiety). Psychological and legal (compensation neurosis) factors should also be considered in certain cases. Post-‐concussive headache is a complex issue and thus early management by experienced neurologists or other physicians who have training in treatment of concussion, traumatic brain injuries and post-‐concussion syndrome is important in improving the patient’s quality of life in the shortest period of time possible. References on request.