Ulnar entrapment neuropathy along the medial intermuscular septum in the midarm.

We report a patient with primary ulnar entrapment neuropathy in the midarm. Stimulation of multiple sites along the ulnar nerve showed a motor conduction block at a distance of 7.5-10 cm proximal to the medial epicondyle, where the nerve was compressed by the medial intermuscular septum. Anatomically, the possibility of ulnar nerve entrapment in this segment has long been suggested, and stimulation at least 10 cm above the medial epicondyle may reveal the entrapment. Muscle Nerve 39: 707-710, 2009.