Neuropathy of motor branch of median or ulnar nerve induced by midpalm ganglion.

Two cases of neuropathy of a motor branch caused by a midpalmal ganglion are presented. In the first case the ganglion originated from the midcarpal joint, protruded into the thenar muscle, and compressed the motor branch of the median nerve. In the second case the ganglion, distal to the fibrous arch of the hypothenar muscles, originated from the third carpometacarpal joint and compressed the motor branch of the ulnar nerve. In both cases muscle weakness and finger deformity recovered well after resection of the ganglion. This clinical condition is rare compared with carpal tunnel syndrome and Guyon's tunnel syndrome, which are caused by a ganglion in the wrist.