Ulnar neuropathy as a result of anconeus epitrochlearis

After carpal tunnel syndrome, cubital tunnel syndrome is the second most common compression neuropathy in the upper extremity. Various sites of ulnar nerve compression at the elbow exist, with the most common being between the 2 heads of the flexor carpi ulnaris. Other potential sites include the arcade of Struthers, the space between Osborne's ligament and the medial ulnar collateral ligament, the medial epicondyle, the medial head of the triceps, and the medial intermuscular septum. The anconeus epitrochlearis, an anomalous muscle that runs between the medial aspect of the olecranon and the medial epicondyle, is found in up to 28% of cadavers. Although it is far less common, it must be considered when evaluating a patient with cubital tunnel syndrome. The authors report a 19-year-old man with a 2-month history of atraumatic left elbow pain accompanied by distal motor and sensory symptoms that significantly affected his activities of daily living and quality of life. After a short course of conservative management, surgical excision of the anomalous muscle, along with decompression of the ulnar nerve, was performed because of progression of symptoms. The patient had immediate improvement in subjective symptoms and strength on removal of the anconeus epitrochlearis. As shown in this case report, recovery of both motor and sensory nerve function can be achieved if the source of compression is an anomalous muscle and is treated with early surgical removal.