Severe Cubital Tunnel Syndrome: Considerations for Nerve Transfer Surgery

Cubital tunnel syndrome is the second most common compressive neuropathy, next to only carpal tunnel syndrome in its incidence. Severe states of disease do not respond to nonoperative management. Likewise, functional outcomes of cubital tunnel surgery decline as the disease becomes more severe. The relatively long distance from site of nerve compression at the elbow to the hand intrinsic muscles distally makes it a race between reinnervation of the muscle and irreversible motor endplate degeneration with muscle atrophy. Loss of intrinsic function can lead to severe functional impairment with poor dexterity and clawing of the hand. While decompressing the nerve at the site of compression is important to prevent further axonal injury, until recently, the only option to restore intrinsic function was tendon transfers. Tendon transfers aim to restore thumb side pinch and control clawing with addition surgery. They also require the sacrifice of wrist extensors or finger flexors. In the past decade, nerve transfers to the distal portion of the ulnar nerve innervating these intrinsic muscles, originally described for proximal ulnar nerve injury or transections, have become increasingly popular as an adjunct procedure in severe cubital tunnel syndrome. Physicians treating severe ulnar neuropathy must be aware of these nerve transfers, as well as their indications and expected outcomes.