Injection injuries to the median and ulnar nerves at the wrist.

Carpal tunnel syndrome is often treated nonoperatively with temporary wrist immobilization and local steroid injections. A direct injection into a peripheral nerve can result in permanent damage. Two cases of median nerve injection injury and one involving the ulnar nerve are presented; all were treated with neurolysis and debridement of the injected material. At follow-up ranging from 1 to 11 years, all patients showed significant improvement, but with some functional loss. The literature is confusing because of the variety of injection techniques used for the treatment of carpal tunnel syndrome, some of which put the median nerve at risk. We recommend that the injection be made midway between the palmaris longus tendon and the flexor carpi ulnaris tendon just proximal to the proximal edge of the transverse carpal ligament in a line with the superficialis tendon of the ring finger. The injection should be stopped and redirected if the patient experiences paresthesia of any kind.