Alternate Names: Median nerve dysfunction

Causes and Risks:

Carpal tunnel syndrome is caused by pressure exerted on the median nerve at the wrist. The median nerve supplies sensation to the thumb-side of the palm, and to the thumb, index finger, middle finger, and the thumb-side of the ring finger. It also supplies movement to part of the hand.

The nerve enters the hand between the wrist bones (called the carpal bones) and the tough membrane that holds the bones together (the transverse carpal ligament). This space is called the carpal tunnel. Since the passageway is rigid, any swelling in this area can cause compression of the nerve (this is also called entrapment of the nerve).

The condition occurs most often in people 30 to 60 years old, and is 5 times more common in women. Some of the conditions associated with carpal tunnel syndrome include pregnancy, premenstrual syndrome (PMS), and menopause. This is probably because of hormone changes that cause fluid retention and swelling of the tissues.

Other conditions associated with carpal tunnel syndrome include rheumatoid arthritis, renal failure, diabetes mellitus, acromegaly, hypothyroidism, multiple myeloma, obesity, recent tuberculosis, fungal infection, and high blood pressure.

Injury or trauma to the area, including (but not limited to) repetitive movement of the wrists, can cause swelling of the tissues and carpal tunnel syndrome. This type of injury may be from sports such as racquetball and handball, or from sewing, typing, driving, assembly-line work, painting, writing, use of tools (especially hand tools or tools that vibrate), or similar activities.

Prevention:

Avoid or reduce the number of repetitive wrist movements whenever possible. Use tools and equipment that are properly designed to reduce the risk of wrist injury.

Symptoms:

• weakness in 1 or both hands
• numbness or tingling in the thumb and next 2 or 3 fingers of 1 or both hands
• numbness or tingling of the palm of the hand
• wrist or hand pain in 1 or both hands can occur
• impaired fine finger movements (coordination) in 1 or both hands
• weak grip or difficulty carrying bags is a common complaint

Signs and Tests:

Physical examination may show decreased sensation in the palm, thumb, index finger, middle finger, and thumb-side (radial surface) of the ring finger and hand grip may be weak. Tapping over the median nerve at the wrist causes pain to shoot from the wrist to the hand (Tinel’s sign). Bending the wrist forward all the way (full flexion--called Phalen’s test) should also reproduce the pain.

Electromyography and nerve conduction velocity may be performed, showing decreased conduction across the wrist. Wrist X-rays may also be recommended.

Treatment:

LIFESTYLE CHANGES:
Night splints for the wrist(s) for several weeks is usually the first line of treatment. If unsuccessful the splints are worn during the day and heat or cold compresses may be added.

Modifications in the work area, work duties, or recreational activities may be necessary. Some of the jobs associated with carpal tunnel syndrome include typing, use of vibrating tools, mine workers, and professional musicians.

There are many specialized devices designed to be used in the workplace to reduce the stress placed on the wrist and improve carpal tunnel syndrome and these should be used when possible.

MEDICATIONS:
Medications used in the treatment of carpal tunnel syndrome include anti-inflammatory analgesics (NSAIDs). The carpal tunnel may also be injected with corticosteroids, and this can provides dramatic relief of symptoms. (Note: It is the carpal tunnel space that is injected, NOT the nerve!)

SURGERY:
Carpal tunnel release is a surgical procedure that cuts into the ligament to relieve pressure on the median nerve. Surgery is successful about 85% of the time, depending on the severity of the problem. Surgery reduces the pressure on the nerve but the damaged nerve must heal for the symptoms to improve. This can take months and in severe cases the nerve may be incapable of fully healing.

Prognosis:

Symptoms often improve with treatment but more than 50% of cases eventually require surgery. Surgery is often successful but full healing can take months.

Complications:

If the condition is treated properly, there are usually no complications. If untreated, the nerve can be damaged, causing permanent weakness, numbness, and tingling.

Call for an appointment with your health care provider if you have symptoms of carpal tunnel syndrome.

Call your health care provider if symptoms of carpal tunnel syndrome do not respond to treatment, or if there seems to be a loss of muscle mass in the fingers.