RxCircle

Causes and Incidence The exact cause is unknown, but highly repetitive flexing motions of the wrist are strongly implicated. Conditions that cause edema (e.g., diabetes, pregnancy, congestive heart failure, and renal failure) also have been suggested as causes. One theory links carpal tunnel syndrome to a vitamin B6 deficiency in conjunction with repetitive movements. The incidence of carpal tunnel syndrome has increased dramatically over the past decade; it is one of the three leading occupational-related conditions in the United States. It occurs most often in women.

Disease Process The median nerve in the volar aspect of the wrist is compressed between the longitudinal tendons of the forearm muscles that flex the hand and the transverse superficial carpal ligament. This causes paresthesias in the thumb, forefinger, and middle finger and half of the ringfinger.

Symptoms Pain, weakness, clumsiness, heaviness, numbness, burning, and tingling in one or both hands are the usual manifestations. The pain may be worse at night and lessen during the day unless the person's activities require repetitive wrist flexion. The pain may radiate to the shoulder and forearm.

Potential Complications If left untreated, carpal tunnel syndrome can cause permanent nerve damage with loss of sensation and movement.

Diagnostic Tests Clinical evaluation with characteristic signs, inability to make a fist, positive Tinel's sign (tingling and burning produced by light tapping over the tendon sheath on the ventral surface of the wrist), positive Phalen's sign (pain or numbness after 30 seconds of wrist flexion), wasting around fingernails; history of repetitive use, underlying disease, last trimester of pregnancy; weakened muscle response on electromyogram.

Treatments

Surgery

Release of carpal ligament for decompression of nerve if conservative measures are ineffective

Drugs

Local corticosteroid injections into tendon sheath to reduce inflammation

General

Restriction of repetitive wrist flexion; cock-up splints at night to reduce nerve pressure and relieve pain