Bilateral ulnar nerve entrapment by the M. anconeus epitrochlearis. A case report and literature review

Ulnar neuropathy at the elbow is the second most common entrapment neuropathy. Ulnar nerve entrapment has several causes. A case report is presented with the presence of the M. anconeus epitrochlearis at both sides. The patient contacted our department with chronic, diffuse bilateral elbow pain irradiating into both forearms. She experienced typical nocturnal paresthesias involving digit IV and V of both hands. Tinel's sign was present just proximal to the medial epicondyle. A bilateral ulnar nerve entrapment was clinically suspected. An electromyographic (EMG) investigation revealed slowing of the motor conduction velocity in the ulnar nerve across the elbow. An ultrasound and MRI investigation demonstrated the presence of an anomalous muscle, called the M. anconeus epitrochlearis, at both sides. Treatment consisted of bilateral surgical excision of the muscle and retinacular release, followed by physical therapy. The outcome was favourable.