Anatomic variations of the median nerve in carpal tunnel release.

Carpal tunnel syndrome (CTS) is a well-known clinical entity. Release of the transverse carpal ligament is considered to be the treatment of choice. Both open and endoscopic release of the transverse carpal ligament in CTS has yielded satisfactory results. Although these procedures are very common in surgical practice, inadequate release and intraoperative damage to neural elements are very frustrating complication for both the patient and the surgeon. The purpose of this study was to demonstrate incidental intraoperative findings of variations of the standard median nerve anatomy. We obtained incidental intraoperative identification of median nerve variations in 110 consecutive patients operated with open release of the transverse carpal ligament in CTS. Using the Amadio classification, we found intraoperatively variations of median nerve at the wrist in 11 patients. In three patients, there was an aberrant sensory branch arising from the ulnar side of the median nerve and piercing the ulnar margin of the transverse carpal ligament. Neural variations arising from the ulnar aspect of the median nerve were common and could be a cause of iatrogenic injury during endoscopic or open release. Surgeons should be aware of anomalous branches, which should be recognized and separately decompressed if needed.