Injury to the deep motor branch of the ulnar nerve during carpal tunnel release.

Complications following carpal tunnel release have been reported to occur in 12-20%’ of cases and are numerous and varied. Neurologic complications that have been reported usually involve the palmar cutaneous or motor branch of the median nerve.’ Ulnar nerve injury during carpal tunnel release has been reported rarely. The only cases reported include cases of injury to the main ulnar palmar cutaneous nerve,* the ramus communicans3 (a normal sensory communication between the ulnar and median nerve in the palm), and a partial ulnar nerve injury in Guyon’s cana1.4 We have encountered three cases of injury to the deep motor branch of the ulnar nerve just distal to the hook of the hamate in the midpalmar space. All injuries occurred during routine carpal tunnel release performed by experienced orthopaedic surgeons and were not appreciated intraoperatively.