Cyclists Palsy - a case study

FEATURE Cyclists Palsy - a case study

Kristy Pritchard

Mountain bikers are generally a stoic and resilient bunch. They race hard, they train hard, they bounce hard, except for my dear husband. This report will describe the events that took place following the Reef to Reef 4 day stage race. reported one or more overuse injuries with 31% of these being overuse related hand pain (Schwellnus & Dorman, 2014). Factors contributing to overuse hand and wrist pain are many and varied and can be summarised in Table 1.

Following the race he was elated, yet told me he was “never doing that again”. In the morning, he reported that he was finding it difficult to use both hands and he had noticed a mild clawing to the ring and little fingers. He could correct the claw with effort however on passive relaxation of the hand, it fell back to the ulnar claw posture. Being the caring diligent spouse that I am, I immediately leapt into action for a rapid assessment and diagnosed him with “cyclist’s palsy”, as that sounded like the logical conclusion.

Cycling injuries that affect the upper limb can be broken into acute injury, such as that following a crash, or an overuse injury. In a survey of 518 recreational cyclists, 85% “Cyclists Palsy”, otherwise known as ulnar nerve neuropathy, is a condition that can arise following direct pressure on the ulnar nerve from the handlebars, while the nerve is in a stretched position from wrist extension. Specifically, the ulnar nerve passes through Guyon’s Canal which is a tunnel bordered by the pisiform and the hook of hamate. Presentation can be variable depending on which branch of the ulnar nerve is involved and can include the following (Brubacher & Leversedge, 2017): • Pain • Paraesthesia in the ulnar ring finger and palmar little finger • Weakness to the little finger in the direction of flexion, abduction and opposition.

Table 1. Individual Variables

Inadequate training

Environmental Variables

Constant vibration

Equipment Variables

High saddle

Gripped hand posture Rough ground Down tilted saddle

Over extended wrist position Insufficient core muscles Downhill increases pressure on the hands Uphill increases the grip force Low handlebars

High pressure tires (FDM, AbDM, ODM) • Weakness in finger abduction and adduction (interossei) • Weakness to the thumb in the direction of adduction. (AddPoll)Ulnar claw by MCP extension and PIP flexion (lumbricals 3 and 4).

Happy with my diagnosis, I advised that he should refrain from cycling until symptoms resolved and reassured him that the nerve was likely just a little bruised and swollen, however shouldn’t lead to long term deficit.

A few days later, he reported the clawing to be less pronounced, however he had noticed a weak pinch and was experiencing difficulty doing up buttons and opening bottles. He displayed a positive Jeanne’s sign (Skirven et al, 2011), where the MCP joint hyperextends in a thumb to index finger pinch. I decided to test for Froment’s sign (Skirven et al, 2011), which was positive. On attempt to hold a flat sheet of paper in a lateral pinch grasp, the paper out easily. I concluded that my diagnosis of ulnar nerve neuropathy was still correct as adductor pollicis could supply a lot of power to this pinch posture.

Within the week I was getting a little exasperated by the constant running commentary. He reported that his thumbs were now the main issue in

I pulled that he could not manipulate freely during fine motor tasks. I would usually expect a mild neuropathy to resolve within two weeks. This particular case was strange in that it actually appeared to be worsening over that first week. On closer inspection, the ulnar digit strength and the clawing did seem to have resolved and the weakness was now more profound in the thenars.

This would be more consistent with a median nerve entrapment at the wrist such as carpal tunnel syndrome. Carpal tunnel syndrome is the most common peripheral nerve entrapment syndrome worldwide. It occurs when the median nerve is compressed at the level of the wrist where it passes through the carpal tunnel. The carpal tunnel is formed by the wrist bones dorsally and the transverse carpal ligament volarly. Symptoms again can vary depending on which nerve branches are compressed. Pain is a common symptom but not always present and in more severe cases the pain can spread proximally into the arm (Padua et al., 2016). Sensory abnormalities such as tingling or numbness usually occur in the median nerve distribution of the palmar radial three digits however it is often reported to be the ‘entire palm’. My husband did not have any sensory symptoms or any pain and his Phalen’s manoeuvre where the wrist is held flexed for 1 minute was negative. He did have a positive Tinel’s sign when percussed over the carpal tunnel for pain that was temporary in nature. Luca Padua et al (2016) reported that the strength of the abductor pollicis brevis muscle would provide useful data for functional impairment, however, it is difficult to get a reliable objective measure of this. They suggest measuring a standard hand grip strength using a dynamometer.

When observed to attempt a tip to tip pinch, he was able to reach the tip of the index finger but not generate significant power and he couldn’t hold the correct posture of slight flexion at the IPJ and MCPJ of the thumb. Functionally, he could not open toothpaste lids and squeezing eye dropper bottles required two hands. As the weeks ticked by, he wondered if he would ever be the same again and I could only be helpful by saying it’s a waiting game.

Further discussions highlighted a possible postural component to the issue. Excessive fatigue and inadequate training coupled with weak core muscles lead to a ‘chest down’ position with thoracic flexion, cervical extension, shoulder flexion, elbow flexion and wrist extension, the habitual resting posture for hours on end (See Figure 1). Smith et al (2008) reported a significantly greater number of cyclists with positive ulnar nerve neuropathy also had positive provocative testing for thoracic outlet syndrome. This logically makes sense with the forward posture required of cycling usually with cervical spine extension and thoracic spine flexion. My bike riding husband has in the past sustained a fractured right clavicle which I speculated could be also a risk factor for double crush syndrome.

Figure 1. Displaying correct and incorrect riding position

To pass the time, the research and online shopping began in earnest as all bikers seem to be addicted to buying new gadgets. He is determined not to have this issue again and the bike now sports a few new modifications.

So What Can be Done?

Prevention of overuse related hand and wrist pain in cyclists is multifactorial: • Gear – let’s face it, this is most likely the only change to be made in many cases willingly • Ergonomics and posture on the bike • Training load control • Adjustments made whilst cycling to alternate grip, hand and wrist position • Off the bike hand exercises and core stability

‘Essential’ Cycling Modifications: • Foam or gel padded gloves to reduce pressure over the carpal tunnel and Guyon’s

Canal. A thin layer has been hypothesised to be superior over too much padding, in pressure reduction achieving 10-28% reduction in hypothenar pressure (Slane et al., 2011) • Curved handlebars (high sweep) to allow the wrists to rest in a more neutral posture, additionally opening up the thoracic outlet by encouraging improved spinal posture on the bike (Figure 2) • Thicker diameter grips to reduce MCPJ/IP flexion (Figure 3). Carbon handle bar and silicon hand grips to reduce vibration • Custom adjustments in bike fit to suit individual arm, trunk and leg length

Particular attention should be brought towards core stability and sitting appropriately on the bike seat. If the core and legs are driving the action, then less pressure will be placed upon the upper limbs.

Figure 2. The back sweep (8 vs 15 degrees) can clearly be seen when handlebars are compared.

Figure 3. Increased diameter of grips.

Signs of fatigue, other than the obvious cardio/respiratory stress, could include the following and indicate a need to rest or change posture: • Overgripping of the handle bars Hunched or kyphosed thoracic spine Pelvis rocking from side to side Overextended wrists

It must be said my husband did make a full recovery in three weeks with rest from the bike, fervent internet shopping and gentle hand use being his main therapy. He has had no similar issues up to the time of writing and plans to repeat the race in 2020 with more training and better setup, including a lot of hand friendly modifications.

Figure 4. When you can’t ride push!

References