Cyclist's palsy

Original Editor - Arno De Maeyer

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Description

Cyclist’s palsy, or ulnar neuropathy, is a familiar affection of the long-distance cyclist, mostly due to overtraining. Another name for this ailment is handlebar palsy. Typically the ulnar nerve becomes irritated and compressed in the wrist within or distal to Guyon's canal, due to the pressure exerted on the hands on the handlebars. This is even intensified when riding on rough terrain. Furthermore, when people are riding the bike, they often have a hyperextended position of the wrist resting on the handlebars or hoods, contributing to the neuropathy by compressing and stretching the nerve as it passes from wrist to hand. [1]
The symptoms include numbness, tingling, weakness, clumsiness, cramping, pain and possibly motor limitation. The term palsy is used because the cyclist's hand often develops muscle paralysis. The affection can impact both sensory and motor functions of the hand, depending on the branch of the ulnar nerve that is affected. [1][2]

It is difficult to determine the exact incidence rate for this type of non-traumatic overuse injury, because typically individuals often consider this injury not severe enough to seek medical care. This means that patient records are not always available. The prevalence of hand and wrist non-traumatic ulnar or median nerve compression described in the literature as manifesting itself in sensory or motor disturbance, ranges from 10% to 70%. This very wide range in frequency can be clarified by the fact that if a study is based on self-reporting by patients, it are mostly those persons who have suffered an injury that will report. This figure should thus not be generalized to the entire cycling population. [5]

Clinically Relevant Anatomy

The ulnar nerve is a branch of the medial cord of the brachial plexus, which travels distally along the medial side of the arm. It passes posteriorly to the medial epicondyle at the elbow, then if follows along the ulna towards the hand. The nerve gives off two sensory branches which supplies sensation to the dorsomedial hand, the 5th digit, and half the 4th digit. At the wrist, the ulnar nerve enters the hand by passing through Guyon’s Canal. This tight tunnel is formed between the hamate, the pisiform, and the pisohamate ligament which helps keep these carpal bones together. Either within or just beyond Guyon's Canal, the ulnar nerve divides again in two motor branches.

In the cyclist, it is at or just before Guyon’s Canal where compressive injury to the ulnar nerve mostly commonly occurs..

Epidemiology/Etiology

Cyclist's palsy typically develops during long-distance or prolonged cycling and occurs with both mountain bike and road cyclists. The position of the hands while holding the handlebar gives pressure on the ulnar nerve in the wrist. This pressure of holding the handlebar in combination with vibrations from the road or trails can be enough to damage the nerve due to compression. Especially when cycling downhill, a large part of the body weight is supported by the hands on the corner of the handlebar. This leads to an even higher load on Guyon’s canal in the wrist. Cyclists also often place their hands in an hyperextended position on the handlebar. All this can cause neuropraxia, a disorder of the peripheral nervous system in which there is a temporary loss of motor and/or sensory function due to blockage of nerve conduction. [1][2][4]
Other factors which can contribute to the occurrence of cyclist's palsy are general fatigue which leads to increased weight bearing on the hands, not changing hand position on the handlebar frequently enough, wearing ill-fitted or worn-out gloves, improper bike fit, using worn-out handlebar paddings, wrong shape or size of the handlebar or malposition of the saddle causing improperly distributed body weight on the hands holding the handlebar. [2][5][6][11]

Characteristics/Symptoms

Symptoms can vary from person to person, but they commonly share similarities. Possible symptoms are weakness, numbness, tingling, and possibly motor limitation along the course of the ulnar nerve.

People often report numbness or tingling in the hand that goes away within a day or two, but can have persistent weakness with pinching and fine finger movements.

Differential Diagnosis

It is important to understand the signs and symptoms of this ailment so that it can be identified and proper diagnosed without having to seek numerous tests.

Assessment of the person's ability to adduct the thumb should be performed. If weakness is apparent, this could be the result of paralysis of adductor pollicis.

Paralysis of the interossei muscles is also possible, and would present as an inability to abduct and adduct all the fingers. To examine, the person places his/her hand on the table and the therapist asks him/her to lift the 3rd finger upwards. The person is then asked to adduct and abduct this finger pertaining to the 4th finger. This is not possible if the person has cyclist’s palsy. In this case, a shift from the flat of the hand and the wrist to the ulnar side would be observed as a compensation.

People withe cyclist’s palsy in advanced stages could have a claw hand, in which case surgery is sometimes indicated.

Diagnostic Procedures

After the initial assessment, additional imaging such as ultrasound, CT-scan, and MRI can be performed to help confirm the diagnosis and determine the location of the compression.

Prevention

Prevention is the most important part in avoiding Cyclist's Palsy, and it can be effectively prevented. Cushioning the pressure points by using padded handlebars and padded cycling gloves is effective. This provides an extra layer or protection to better absorb shock and protect from pressure.

The position of the hands on the handlebars is also important. Individual sizing/fitting of the handlebar and riding position is crucial for preventing this condition. The cyclist should regularly change the hand position on bars.

Enthusiastic long-distance cyclists should also adopt a comfortable and resilient riding posture. If the trunk musculature gets fatigued, the hands will invariably bear more weight to stabilize him/her on the bike. Developing a better posture on the bike requires strong trunk muscle endurance.

Treatment

This type of nerve injury is self-limiting. The nerve will regenerate on its own, resulting in the restoration of hand muscle function; however, symptoms of handlebar palsy can take weeks to months to heal. While the nerve regenerates, the person needs to interrupt his/her sport activities temporarily. Prevention is important for this type of neuropraxia (see prevention above), as well as ensuring the cyclist rides on the right size of bicycle and the handlebars are appropriately positioned.