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Carpal tunnel syndrome: treating a common ailment

I've been experiencing numbness and tingling in my fingers. I am afraid I may have carpal tunnel syndrome. What is carpal tunnel syndrome and how can I treat it?

In recent years, the value of proper posture in the workplace to reduce strain on the body has been recognized. As employees have become more aware of the damage repetitive tasks -- such as using a computer keyboard -- can do, carpal tunnel syndrome (CTS) has become a common complaint.

Although a multitude of aches and pains in the wrist and forearm are often considered CTS, in order to make the diagnosis it is necessary to demonstrate that the pain in question is resulting from the compression of a nerve that runs through the wrist.

"When the median nerve is compressed, the resulting numbness or pain is known as carpal tunnel syndrome," says Andrew Stein, M.D., a hand surgeon in the department of orthopedics at Boston Medical Center and an assistant professor in MED's department of orthopedic surgery. "This occurs in a predictable location and is reproducible with a few simple provocative tests in the office."

The carpal tunnel is a narrow passageway located on the underside of the wrist. It is formed by the bones of the wrist and the ligament that connects the base of the thumb to the heel of the hand. The median nerve that passes through the opening is what can become aggravated. The nine tendons that connect to the fingers and thumb also pass through the carpal tunnel, which is approximately two inches wide and about an inch deep. A repetitive task, such as typing, can aggravate the nerve.

Physicians and researchers agree on a few proven risk factors. Women, especially pregnant women, seem to develop CTS at higher rates than other groups. Individuals who suffer from diabetes or rheumatoid arthritis also seem to be at greater risk. Evidence of other causes of CTS (such as repetitive stress), however, is inconclusive.

Those with CTS complain of three main types of discomfort: numbness in the thumb, index, middle, and part of the ring fingers; tingling in those same fingers, which can be worse at night; and ill-defined pain in the extremities. Patients experiencing pain during the night that is severe enough to wake them are strongly encouraged to see a physician. The impact of CTS can lessen over time, but often the condition worsens and episodes of pain and discomfort become more frequent.

"Patients often complain that they have symptoms only at night or in the morning and they go away as the day progresses," Stein says. "When we sleep, our wrists are often bent at an angle, which can aggravate an already irritated nerve. During the day, however, the wrist is usually straight, which is why the pain goes away."

Wearing a wrist splint at night to keep the wrist straight is the simplest treatment for CTS, Stein says. The next step is a cortisone injection, which will shrink any inflammation around the median nerve and tendons. "Approximately 80 percent of people who experience a cortisone injection will receive some relief, but only 20 percent will have complete relief after a year," he says.

In severe cases of CTS, doctors will perform a procedure known as a carpal tunnel release. The ligament that connects the base of the thumb and the heel of the hand is cut, opening up the carpal tunnel area and allowing more room for the median nerve. According to Stein, cutting the ligament doesn't negatively impact hand strength, which takes about three months to recover.

If CTS is left untreated, it can result in a loss of fine motor skills in the hands. It can also progress to the point that the median nerve stops functioning altogether and finger muscles atrophy. "Seeing a doctor is a good idea if you have numbness or tingling in your hands on a regular basis," Stein says. "If you are diagnosed with carpal tunnel syndrome, it's best to treat it before it permanently impacts hand function."

"Health Matters" is written in cooperation with staff members of Boston Medical Center. For more information on carpal tunnel syndrome or other health matters, call 617-638-6767.

19 January 2001
Boston University
Office of University Relations