Acute compression of the median nerve at the elbow by the lacertus fibrosus.

Chronic compression of the median nerve at the elbow has been described as resulting from a number of structures including the lacertus fibrosus. Symptoms of chronic compressive peripheral neuropathy consist predominantly of an achy feeling, paresthesias, numbness, and a sense of weakness or fatigue, with the onset being insidious and frequently without a precipitating cause. In this series, 7 consecutive cases of acute median nerve compression in the antecubital fossa resulted from an extremely forceful injury to the elbow. In all 7 cases, a sudden, severe attempt at elbow flexion was performed against a substantial counterforce, resulting in immediate severe pain radiating from the elbow down into the forearm. Pain was persistent and unremitting in all 7 until the time of diagnosis and treatment. Surgical decompression was performed in all cases. At the time of surgery, we found evidence of partial rupture of the myotendinous junction of the biceps brachii creating increased tension across the median nerve by a tethered lacertus fibrosus. Surgical decompression resulted in complete relief of symptoms in all 7 cases.