[Isolated compression of the motor branch of the ulnar nerve].

This paper reports four cases of isolated compression of the deep branch of the ulnar nerve, and reviews the various etiologies (tumor, malformation and microtraumatism). The authors stress the importance of the electric examination, particularly conduction velocity in the palm in localizing the nerve lesion. Surgical exploration in these cases revealed a Giant cell tumor, two synovial cysts, and an abnormal fibrous band stretching between the flexor digiti quinti brevis and the opponens digiti quinti. Postoperative courses were uncomplicated and every patient recuperated quickly and completely. Early surgical exploration in such cases is mandatory.