Carpal Tunnel Syndrome
Related narrative: Open Carpal Tunnel Release
Epidemiology and Risk Factors
Carpal tunnel syndrome occurs when tendons in the wrist become inflamed after being aggravated, and the carpal tunnel narrows, pinching the median nerve. The first symptoms usually appear at night. Symptoms range from a burning, tingling numbness in the fingers, especially the thumb and the index and middle fingers, to difficulty gripping or making a fist. Nonsurgical intervention includes wearing a brace or splint and hydrocortisone injections. Surgery is performed on those for whom medical intervention is unsuccessful. This surgery is the most common type of hand and wrist surgery done, with an estimate of over 400,000 per year in the United States. Carpal tunnel syndrome occurs in five times more women than men; people between 30 and 60 years old; people who are overweight and/or physically inactive; or people whose work causes repetitive hand motions or flexion. It is also associated with a number of other conditions, such as pregnancy, diabetes, thyroid dysfunction, rheumatoid arthritis, and Raynaud disease. Tumorous conditions, such as ganglions or lipomas can contribute to the condition, as can a misaligned Colles fracture.
The clinical presentation for carpal tunnel syndrome includes numbness and tingling in the hands, especially when these symptoms occur at night and after use of the hands; decreased feeling in the thumb, index, and middle finger; electric-like shock or tingling (Tinel sign) when tapping over the course of the median nerve at the wrist; the reproduction of symptoms by holding wrists in a bent down position for one minute (Phalen test). Thenar atrophy is sometimes seen in chronic cases. Nerve conduction tests are sometimes taken as the gold standard for diagnosis, but studies have reported sensitivity as high at 90% and specificity of 60%, so this testing may be somewhat limited in usefulness. Neither CT nor ultrasound is adequate, but there have been positive reports of diagnostic evaluation using MRI. Carpal tunnel syndrome can be confused with compression caused by cervical disc herniation or thoracic outlet structures, or compression in the forearm or elbow rather than the wrist.
Five factors have been identified that help determine the success of nonoperative treatment: 1) >50 years old; 2) >10 months duration of symptoms; 3) constant paresthesia; 4) stenosing flexor tenosynovitis, and 5) positive Phalen test in <30 seconds. In the study, the number of risk factors dictated the success of treatment without surgery; almost no patients with three or more risk factors were treated successfully through medical management alone.
There are two basic approaches to the surgical release of carpal tunnel: open and endoscopic. Open techniques include a double incision and short or minimal incision. Endoscopic techniques include primarily the Agee "single portal" and the Chow "two portal." Studies comparing endoscopic and open approaches report significantly less scarring, less ulnar "pillar" pain, a faster return of strength, and a quicker return to work and normal activity. Contraindications to using an endoscopic technique include the need for neurolysis, tenosynovectomy, Z-plasty of the transverse carpal ligament, or decompression of the Guyon canal; the presence of infection or severe swelling; the suspicion of a space-occupying lesion or abnormality; anatomical variation in the area; previous surgical scarring; or if the surgery is a revision for recurrent problems. Endoscopic expertise is required, and there is a high learning curve for this technically demanding procedure.
Complications for both procedures can include transient nerve paresthesias, palmar arch injury, reflex sympathetic dystrophy, flexor tendon laceration, and incomplete transverse carpal ligament division. A meta-analysis of the literature on the endoscopic techniques showed a complication rate of about 2.7% and a failure rate of 2.6%, which is similar to the open procedure, but endoscopic procedures resulted in significantly less pain in the first few weeks of recovery and faster return to normal activity. However, some data suggest that recurrence is more frequent after endoscopic surgery than open surgery.
Agee, JM, McCarroll, HR, North, ER. Endoscopic carpal tunnel release using the single proximal incision technique. Hand Clin 1994 Nov; 10(4):647-59.
Boeckstyns, ME. Does endoscopic carpal tunnel release have a higher rate of complications than open carpal tunnel release? An analysis of published series. J Hand Surg 1999 Feb; 24(1):9-15.
Brief, R and Brief, LP. Endoscopic carpal tunnel release: report of 146 cases. Mt Sinai J Med 2000 Sept; 67(4): 274-277.
Concannon, MJ, Brownfield, JL, Puckett, CL. The incidence of recurrence after endoscopic carpal tunnel release. Plast Reconstr Surg 2000 Apr; 105(5): 1662-1665.
Jimenez, DF. Endoscopic treatment of carpal tunnel syndrome: a critical review. J Neurosurg 1998 May; 88(5): 817-826.
Mackenzie, DJ. Early recovery after endoscopic vs. short-incision open carpal tunnel release. Ann Plast Surg 2000 Jun; 44(6): 601-604.
Wright, PE. Carpal tunnel and ulnar tunnel syndromes and stenosing tenosynovitis. In Canale (ed.) Campbell's Operative Orthopaedics, 9th ed., St. Louis, MO: Mosby, Inc.; 1998. p. 3685.