Nerve Transfers in the Upper Extremity: A Practical User's Guide.

Nerve injuries above the elbow are associated with a poor prognosis, even with prompt repair and appropriate rehabilitation. The past 2 decades have seen the development of numerous nerve transfer techniques, by which a denervated peripheral target is reinnervated by a healthy donor nerve. Nerve transfers are indicated in proximal brachial plexus injuries where grafting is not possible or in proximal injuries of peripheral nerves with long reinnervation distances. Nerve transfers represent a revolution in peripheral nerve surgery and offer the potential for superior functional recovery in severe nerve injuries. However, the techniques have not been universally adopted due in part to a misconception that nerve transfers can only be understood and performed by superspecialists. Nerve transfer procedures are not technically difficult and require no specialized equipment. Numerous transfers have been described, but there are a handful of transfers for which there is strong clinical evidence. To restore shoulder abduction and external rotation in upper trunk brachial plexus injury, the key transfers are the spinal accessory to suprascapular nerve and the medial triceps branch to axillary nerve. For elbow flexion, the flexor carpi ulnaris branch of ulnar nerve to the biceps and brachialis branches of the musculocutaneous nerve is the key transfer. For ulnar intrinsic function, the distal anterior interosseous nerve to ulnar motor branch transfer has yielded excellent functional results. Nerve transfers form a therapeutic triad with traditional tendon transfers and functional motor unit rehabilitation which, when applied appropriately, can yield excellent functional results in complex nerve injuries. Nerve transfers are a powerful yet underused tool for proximal nerve injuries, which offer hope for traditionally discouraging injuries.