Cyclist's palsy

Original Editor - Arno De Maeyer

Top Contributors - Lucinda hampton, Wanda van Niekerk, Evan Thomas, Kim Jackson, Kenneth de Becker, Vanessa Rhule, Scott Buxton, Anas Mohamed, Chrysolite Jyothi Kommu, Admin, Arno De Maeyer, Claire Knott, Laura Ritchie, Wendy Walker and Naomi O'Reilly  

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

The exact symptoms of cyclist's palsy may vary from one person to another, depending on the severity of the condition, but mostly depending on whether only the sensory branch the ulnar nerve is impacted, or only the deep motor branch, or both. [6]
Compression of the sensory branch of the ulnar nerve will present itself in sensory disturbances, such as numbness and tingling in the ulnar innervated areas of the affected hand, namely the ring finger and the little finger. These symptoms are easily recognisable and often go away within a day or two. [2][6]
Compression of the deep motor branch of the ulnar nerve will present itself in motor deficits, such as weakness, clumsiness and possibly motor limitation due to loss of muscle function in the hand. These latter symptoms are often less distinguishable and if no sensory fibers are equally affected, a patient might continue cycling with an on-going compression of the motor branch, not realizing that there is an injury until a severe lesion develops. When there is a prolonged outage of innervation of the muscles in the hand by the ulnar nerve, the image of a 'claw' hand can be seen, with particular palmar flexion of the 4th and 5th digit . Correct and timely treatment of this injury is important and the healing process can take from some week to some months. In case a patient does not receive treatment, the ulnar nerve entrapment can cause atrophy of the intrinsic hand muscles or a paresthesia of the hand muscles innervated by the ulnar nerve, which will be permanent. [2][4][6][7]

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.

Another important question in the differential diagnosis of ulnar nerve entrapment is which part of the ulnar nerve is affected. Compressions of the ulnar nerve at the level of the elbow (i.e. cubital tunnel syndrome) or the neck (i.e. scalenus syndrome) require different treatment. Additional examination is needed to trace the exact place of compression and underpin the diagnosis with more certainty. When comparing the symptoms of cyclist's palsy with cubital tunnel syndrome (which occurs more frequently), a different clinical image is seen. People
 
who suffer from the cubital tunnel syndrome primarily suffer from sensory signs which occur in an early phase and get a faster diagnosis. They rarely have a claw hand. This 'claw' hand particularly occurs when there is a prolonged outage of innervation of the muscles by the ulnar nerve, which causes atrophy. Because often no sensory fibers are affected with cyclist's palsy, a claw hand can develop in an advanced stage of the disease. [16][17][21]
Apart from ulnar nerve compression at Guyon's canal resulting from pressure during cycling, there are a number of other injuries that can cause ulnar neuropathy in the wrist by compression. A fracture of the hamate bone or trombosis or aneurysm of the ulnar artery can also put pressure on the ulnar nerve. Other causes of compression at Guyon's canal can be a hypermobile pisiform bone, occupational traumatic neuritis, musculotendinous arch, tenosynovitis of the flexor tendons, crutch use, osteoarthritis, nodular synovitis (giant cell tumor) and compression from wrist ganglions, lipoma or other tumors in the wrist. Developing carpal tunnel syndrome can also result in ulnar entrapment. In case of carpal tunnel syndrome, the shape of the carpal and ulnar tunnel will change, or when surgery is performed to release the carpal tunnel, it is possible that the ulnar tunnel is touched, which can cause damage of the ulnar tunnel. It is thus important to differentiate and to determine the exact cause of the symptoms. [6][7][8][9][10][11][12][13]

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.If the patient indicates the region where there is an abnormal feeling and this region is maximum 6 cm above the wrist, then we can be sure that it involves an ulnar nerve entrapment. But if it is situated more than 6 cm above the wrist, then it involves a cubital tunnel syndrome. [7]
When we are able to localize the exact place on the hand where the patient has a numb feeling, we can differentiate between a carpal tunnel syndrome or an ulnar tunnel syndrome. It is thus crucial to locate the exact place of compression and to differentiate it from other diseases. [7]

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.