Carpal tunnel syndrome

Definition

Carpal tunnel syndrome is a disorder caused by compression at the wrist of the median nerve supplying the hand, causing numbness and tingling.

Description

The carpal tunnel is an area in the wrist where the bones and ligaments create a small passageway for the median nerve. The median nerve is responsible for both sensation and movement in the hand, in particular the thumb and first three fingers. When the median nerve is compressed, an individual's hand will feel as if it has "gone to sleep."

Women between the ages of 30 and 60 have the highest rates of carpal tunnel syndrome. Research has demonstrated that carpal tunnel syndrome is a very significant cause of missed work days due to pain. In 1995, about $270 million was spent on sick days taken for pain from repetitive motion injuries.

Causes & symptoms

Compression of the median nerve in the wrist can occur during a number of different conditions, particularly those conditions which lead to changes in fluid accumulation throughout the body. Because the area of the wrist through which the median nerve passes is very narrow, any swelling in the area will lead to pressure on the median nerve. This pressure will ultimately interfere with the nerve's ability to function normally. Pregnancy, obesity, arthritis, certain thyroid conditions, diabetes, and certain pituitary abnormalities all predispose to carpal tunnel syndrome. Other conditions which increase the risk for carpal tunnel syndrome include some forms of arthritis and various injuries to the arm and wrist (including fractures, sprains, and dislocations). Furthermore, activities which cause a person to repeatedly bend the wrist inward toward the forearm can predispose to carpal tunnel syndrome. Certain jobs which require repeated strong wrist motions carry a relatively high risk of carpal tunnel syndrome. Injuries of this type are referred to as "repetitive motion" injuries, and are more frequent among secretaries who do a lot of typing, people working at computer keyboards or cash registers, factory workers, and some musicians.

Symptoms of carpal tunnel syndrome include numbness, burning, tingling, and a prickly pin-like sensation over the palm surface of the hand, and into the thumb, forefinger, middle finger, and half of the ring finger. Some individuals notice a shooting pain which goes from the wrist up the arm, or down into the hand and fingers. With continued median nerve compression, an individual may begin to experience muscle weakness, making it difficult to open jars and hold objects with the affected hand. Eventually, the muscles of the hand served by the median nerve may begin to grow noticeably smaller (atrophy), especially the fleshy part of the thumb. Untreated, carpal tunnel syndrome may eventually result in permanent weakness, loss of sensation, or even paralysis of the thumb and fingers of the affected hand.

Diagnosis

The diagnosis of carpal tunnel syndrome is made in part by checking to see whether the patient's symptoms can be brought on by holding his or her hand with the wrist bent for about a minute. Wrist x rays are often taken to rule out the possibility of a tumor causing pressure on the median nerve. A physician examining a patient suspected of having carpal tunnel syndrome will perform a variety of simple tests to measure muscle strength and sensation in the affected hand and arm. Further testing might include electromyographic or nerve conduction velocity testing to determine the exact severity of nerve damage. These tests involve stimulating the median nerve with electricity and measuring the resulting speed and strength of the muscle response, as well as recording the speed of nerve transmission across the carpal tunnel.

Treatment

Carpal tunnel syndrome is initially treated with splints, which support the wrist and prevent it from flexing inward into the position that exacerbates median nerve compression. Some people get significant relief by wearing such splints to sleep at night, while others will need to wear the splints all day, especially if they are performing jobs which stress the wrist.

The activity which caused the condition should be avoided whenever possible. Also, the actions of making a fist, holding objects, and typing should be reduced. The patient's work area should be modified to reduce stress on the body. This may be achieved by correct positioning and with ergonomically designed furniture. Performing hand and wrist exercises periodically throughout the day can be beneficial.

Researchers found that the carpal ligament can be lengthened or released without surgery through osteopathic manipulation and weight loading. Combining the two gave additional benefit because manipulation lengthens the ligament at one end and weight loading increases the length at the other end. Patients can be taught a stretching exercise for self-manipulation of the ligament.

A National Institute of Health (NIH) panel concluded that traditional acupuncture may be a useful alternative or complementary treatment for carpal tunnel syndrome. Studies have shown that both laser acupuncture and microamp transcutaneous electrical nerve stimulation (TENS) can significantly reduce the pain associated with carpal tunnel syndrome. Both of these therapies are painless. Greater than 90% of the patients treated reported no pain or pain that had been reduced by more than half. Patients in this study were also using Chinese herbal medicines, deep acupuncture (including needle acupuncture), moxibustion, and omega-3 fish oil capsules. All patients were able to return to work and the pain of most patients remained stable for up to two years. Persons over the age of 60 years had a poorer response.

Some studies have shown that persons with carpal tunnel syndrome are deficient in vitamin B₆ (pyridoxine) and that supplementation with this vitamin is beneficial. Carpal tunnel syndrome should improve within two to three months by taking 100 mg three times daily. The patient should consult with his or her physician when taking high doses of this vitamin.

Chinese and homeopathic remedies include:

• arnica; 30c dose
• astra essence
• Rhus toxicodendron; 6c dose
• Ruta graveolens; 6c dose

Allopathic treatment

Ibuprofen or other nonsteroidal anti-inflammatory drugs may be prescribed to decrease pain and swelling. Diuretics may be used if the syndrome is related to the menstrual cycle. When carpal tunnel syndrome is more advanced, steroids may be injected into the wrist to decrease inflammation.

The most severe cases of carpal tunnel syndrome may require surgery to decrease the compression of the median nerve and restore its normal function. Such a repair involves cutting that ligament which crosses the wrist, thus allowing the median nerve more room and decreasing compression. This surgery is done almost exclusively on an outpatient basis and is often performed without the patient having to be made unconscious. Careful injection of numbing medicines (local anesthesia) or nerve blocks (the injection of anesthetics directly into the nerve) create sufficient numbness to allow the surgery to be performed painlessly, without the risks associated with general anesthesia. Recovery from this type of surgery is usually quick and without complications.

Expected results

Without treatment, continued pressure on the median nerve puts the patient at risk for permanent disability in the affected hand. Alternative medicines have been shown to reduce pain. Most people are able to control the symptoms of carpal tunnel syndrome with splinting and anti-inflammatory agents. For those who go on to require surgery, about 95% will have complete cessation of symptoms.

Prevention

Avoiding or reducing the repetitive motions that put the wrist into a bent position may help to prevent carpal tunnel syndrome. People who must work long hours at a computer keyboard, for example, may need to take advantage of recent advances in ergonomics and position the keyboard and computer components in a way that increases efficiency and decreases stress. Early use of a splint may also be helpful for persons whose jobs put them at risk of carpal tunnel syndrome.

Key Terms

Carpal tunnel

A passageway in the wrist, created by the bones and ligaments of the wrist, through which the median nerve passes.

Electromyography

A type of test in which a nerve's function is tested by stimulating a nerve with electricity, and then measuring the speed and strength of the corresponding muscle's response.

Ergonomic

The science relating to a person and his/her work which strives for the efficient use of human energy.

Median nerve

A nerve which runs through the wrist and into the hand. It provides sensation and some movement to the hand, the thumb, the index finger, the middle finger, and half of the ring finger.

Further Reading

For Your Information

Books

• Asbury, Arthur K. "Carpal Tunnel Syndrome." In Harrison's Principles of Internal Medicine. edited by Anthony S. Fauci, et al. New York: McGraw-Hill, 1998.
• Crouch, Tammy. Carpal Tunnel Syndrome and Repetitive Stress Injuries. Berkeley, CA: Frog, 1995.

Periodicals

• Branco, Kenneth, and Margaret A. Naeser. "Carpal Tunnel Syndrome: Clinical Outcome After Low-Level Laser Acupuncture, Microamps Transcutaneous Electrical Nerve Stimulation, and Other Alternative Therapies-An Open Protocol Study." The Journal of Alternative and Complementary Medicine. 5 (1999):5-26.
• Brody, Jane E. "Experts on Carpal Tunnel Syndrome Say that Conservative Treatment is the Best First Approach." The New York Times. 119 (February 28, 1996): B9+.
• "Carpal Tunnel Syndrome." Postgraduate Medicine. 98 no. 3 (September 1995): 216.
• Glazer, Sarah. "Repetitive Stress Injury: A Modern Malady." The Washington Post. 110 (March 12, 1996): WH12.
• Lucas, B. "Nonsurgical Technique for Carpal Tunnel Syndrome." Patient Care. 33(March 15, 1999):12.
• Seiler, John Gray. "Carpal Tunnel Syndrome: Update on Diagnostic Testing and Treatment Options." Consultant. 37 no. 5 (May 1997):1233+.

Organizations

• Association for Repetitive Motion Syndromes. P.O. Box 514, Santa Rosa, CA 95402. (707) 571-0397.

Gale Encyclopedia of Alternative Medicine. Gale Group, 2001.