Cyclist's palsy: Neurological and EMG study in 4 cases with distal ulnar lesions

Four cases of cyclist's palsy -- a distal compression syndrome of the ulnar nerve which can develop after long cycling tours -- are described. In two patients extensive neurological and electromyographic (EMG) studies were performed in order to document the degree and time course of recovery of the motor and sensory deficiencies. In contrast to either EMG-studies it could be demonstrated that not only the deep motor branch of the ulnar nerve is involved, but also that a severe lesion of the superficial branch supplying the skin of the 4th and 5th finger can occur, as indicated by a complete loss of the orthodromic sensory action potential recorded above the ulnar nerve in both cases. The results furthermore show that a functionally significant paresis of the hand muscles can persist for several months. The pathogenesis and some practical implications will be discussed.