Disclosures: Matthew R. Kelly, MD: Nothing to disclose

Case Description: 41-year-old male with elbow flexor weakness and paresthesias after right long head of the biceps tendon (LHBT) tenodesis. Patient presented 4 months after arthroscopic-assisted open biceps tenodesis to address a painful, partial thickness tear of the LHBT. Post-operatively, he noted weakness in elbow flexion and dysesthesias of the lateral forearm. He completed physical therapy without significant improvement and noted ongoing functional limitations due to weakness.

Setting: Multidisciplinary Peripheral Nerve Clinic.

Patient: 41-year-old male.

Assessment/Result: At presentation, examination demonstrated right biceps atrophy with brachioradialis hypertrophy. There was obvious weakness in right elbow flexion, particularly in supination, and diminished sensation in the lateral antebrachial cutaneous (LABC) nerve distribution. Electrodiagnostic evaluation demonstrated an absent right LABC sensory nerve action potential (SNAP) with a normal contralateral SNAP. Electromyography (EMG) demonstrated increased insertional activity (2+ positive sharp waves and fibrillation potentials) and polyphasic motor unit action potentials in the right biceps. Brachioradialis EMG was normal. CT of the right shoulder was unremarkable, however ultrasound examination demonstrated mild focal swelling of the musculocutaneous nerve (MCN) proximal to the tenodesis site, leading to confirmatory imaging with MRI. Findings on both are consistent with an iatrogenic MCN injury.

Discussion: LHBT tenodesis is a safe procedure, however, due to the proximity of the brachial plexus, nerve injury can result during surgical traction. Arising from the lateral cord of the brachial plexus, the MCN is particularly susceptible during procedures involving the humerus or biceps tendon. A thorough anatomic understanding of the shoulder can help prevent iatrogenic injury and, similarly, aid in post-operative diagnosis.

Conclusion: MCN injury is an uncommon complication of biceps tenodesis. Physicians should have a high clinical suspicion for nerve injuries in post-operative patients presenting with weakness and sensory deficits. Even with unremarkable initial imaging, knowledge of surgical anatomy and peripheral nerve distributions can help guide a focused exam and structure further diagnostic work-up.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/musculocutaneous-neuropathy-following-long-head-of-the-biceps-tenodesis-an-uncommon-surgical-complication/