A Case of Isolated Musculocutaneous Nerve Injury Following Motorcycle Accident

J Korean Assoc EMG Electrodiagn Med 2005;7(2):128-133.
Published online May 10, 2005.

Abstract

Isolated paralysis of the musculocutaneous nerve, as reported in the literature, is uncommon and usually caused by direct traumas. Lesions not associated with direct traumas are rare and usually occur after repetitive high demand activities. This is a report of the musculocutaneous nerve injury following a single episode of overloading accompanied by a motorcycle accident without any fractures, dislocation or external traumas, which might have caused direct nerve injuries. The lesion in this case was thought to be below the coracobrachialis muscle, leaving the coracobrachialis muscle intact and involving the biceps, brachialis and lateral antecubital cutaneous nerve. On initial electromyographic examination at three months after the injury, the lesion was so severe that abundant abnormal spontaneous activities and no voluntary motor units were seen in the biceps brachii and brachialis muscles. At seven months since the onset of symptoms, the biceps muscle showed many abnormal spontaneous activities with only a single motor unit action potential recruited. We report a case of an isolated musculocutaneous nerve lesion not caused by a direct nerve insult, involving distal to the coracobrachialis, and showing severe axonotmesis, which has been reported rarely.

Key Words: Isolated musculocutaneous nerve injury, Electromyography, Motorcycle accident