Cyclist’s Neuropathy

Abstract

Objective: Clinical presentation of the ulnar nerve lesions in the wrist and hand shows variations because of complex anatomic course of the nerve in distal sites. Cyclist’s palsy has been postulated to be an entrapment neuropathy of the ulnar nerve in the Guyon canal of the wrist. We report a case compression of the deep motor branch of the ulnar nerve as cyclist’s palsy in women learning to ride a bike. Case Report: Hand weakness with no evidence of sensory symptoms was the initial presentation that brought the patient to the physician. Her thumb adduction was grade 3/5, fingers’ adduction and abduction were grade 3/5, flexions from the fourth and fifth metacarpaphangeal joint were grade 4/5, and froment’s sign was positive. Routine motor nerve conduction studies on the left ulnar nerve recording from abductor digiti minimi muscle were normal. However, stimulation from the left wrist and recording from the first dorsal interosseous muscle revealed a small amplitude (2.2 mV) and a prolonged distal latency (4.7 ms). The needle electromyography studies showed fibrillation potentials and positive sharp waves in the left first and third interosseous muscles and the adductor pollicis muscle. Conclusions: This may be owing to the fact that tight grasp in an inappropriate position and hyperextension position of the hand during biking are thought to be the main mechanisms of this lesion type.