[Isolated truncular paralysis of the musculocutaneous nerve of the upper limb].

Isolated palsy of the musculocutaneous nerve, terminal branch of the lateral cord of the brachial plexus, is rare. It is responsible for sensory loss of the distal forearm and weakness of elbow flexion. It occurs after shoulder or clavicle surgery, trauma (fracture, dislocation, blows on the shoulder), violent exercice or extension of the forearm, prolonged positioning of the shoulder in extension-abduction-external rotation and phlebotomy. Different mechanisms such as stretching, compression or direct nerve injury are encountered. We report 5 cases with isolated musculocutaneous nerve palsy, including bilateral palsy caused by violent forearm extension. In other cases, mechanisms were an extensive stretching during surgery and compression caused by prolonged supine position. Different injury locations and causes described in literature are reviewed.