Disclosures: Emily L. Wang, MD: Nothing to disclose

Case Description: Ulnar neuropathy due to anconeus epitrochlearis hypertrophy.

Setting: Outpatient sports medicine clinic.

Patient: A 44-year-old man presented to clinic with a history of bilateral forearm numbness and pain. He had lifted weights intensely for years. He was diagnosed as having bilateral radial tunnel syndrome. He was referred for corticosteroid injections but did not follow up. Five years later, he came back to clinic for further evaluation of persistent forearm pain. He described pain over his left medial elbow radiating to the 4th and 5th digits bilaterally. The pain was worsened by prolonged flexion of his elbow and woke him at night.

Assessment/Results: On physical exam he was a muscular man with full range of motion at the elbows, with pain to palpation at the forearm flexor compartment. He had a positive Tinel’s sign on cubital hyperflexion. An MRI of the left elbow showed a prominent anconeus epitrochlearis with compression of the ulnar nerve at the cubital tunnel.

Discussion: In weightlifting and other strength training activities, elbow complaints are common. Compared to nonathletes, in whom cubital tunnel syndrome is often due to compression by a fascial or ligamentous structure, in athletes, a muscular cause of entrapment, such as an anconeus epitrochlearis, should also be considered. The anconeus epitrochlearis is a vestigial accessory muscle that is present in a third of the population. Anconeus epitrochlearis is a rare cause of cubital tunnel syndrome but has been reported in case studies. Cubital tunnel syndrome caused by an anconeous epitrochlearis is best diagnosed through imaging. MRI reveals hypertrophy of the muscle in the cubital tunnel and an enlarged, edematous nerve.

Conclusion: Cubital tunnel syndrome is seen in throwing athletes, such as baseball pitchers, where edema and enlargement of the anconeus epitrochlearis can lead to ulnar neuropathy. Weightlifting may also produce hypertrophy of the muscle and cause ulnar nerve entrapment.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/anconeus-epitrochlearis-hypertrophy-causing-chronic-forearm-and-hand-pain-due-to-ulnar-neuropathy-a-case-report/