Lateral Antebrachial Cutaneous Nerve as In Situ Nerve Graft in Lower Brachial Plexus Injury

The flexor pollicis longus muscle and flexor digitorum profundus muscle are innervated by the branches of the anterior interosseous nerve (AIN). Therefore, the commonly used methods of restoring the fingers and thumb flexion in lower brachial plexus injury have mainly focused on the AIN. We transferred the brachialis muscle branch of the musculocutaneous nerve (brachialis nerve) to the AIN using the vascularized lateral antebrachial cutaneous nerve (LACN) as a nerve graft to restore the flexion function of the fingers and thumb. This anatomical study was performed in 16 formalin-fixed upper extremities from 8 frozen cadavers. The brachialis nerve and the AIN were dissected. The bridged portion of the transected LACN was not dissected; only the two transected ends of the LACN were dissected, which kept the native blood supply of the intervening graft of the LACN from being destroyed. The diameters of the transected nerve ends of the brachialis nerve, AIN, and proximal and distal ends of the LACN were measured separately. Specimens of the measured nerve tissue were sent for toluidine blue staining, and the number of nerve fibers in each transected nerve branch was counted. The diameters of the brachialis nerve, AIN, and proximal and distal transected ends of LACN were 1.37 SD0.25 mm, 1.54 SD0.14 mm, 2.07 SD0.29, and 1.76 SD0.14 mm, with 1109 SD422, 1318 SD546, 1684 SD327, and 1378 SD667 myelinated nerve fibers, respectively. The fingers and thumb flexion function of the patient recovered gradually from 8 months after surgery. Using the vascularized LACN as an in situ nerve graft to transfer the brachialis nerve to the AIN was a feasible alternative technique to restore the flexion function of fingers and thumb in lower brachial plexus injury.