What Is It?

In the wrist, nerves and tendons pass through a space between bones and ligaments called the carpal tunnel.

Because the carpal tunnel is somewhat narrow, the median nerve, a major nerve that passes through this tight space, can become irritated or compressed. Carpal tunnel syndrome is a combination of numbness, tingling, pain and weakness in the hand caused by compression of the median nerve in the carpal tunnel.

Symptoms tend to be most prominent in thumb, index finger, middle finger and half of the ring finger because the median nerve provides sensation to those areas.

Even a small additional narrowing or other injury can lead to nerve irritation. There are several common causes, including:

• Arthritis or fracture near the wrist
• Pregnancy
• Diabetes
• Overuse (as in typists, cashiers or certain athletes)
• Thyroid disease, particularly an underactive thyroid

In each of these conditions, there is either nerve injury or added pressure in the carpal tunnel.

Often, carpal tunnel syndrome occurs without a clear reason. The condition affects women more often than men, perhaps because women normally have smaller carpal tunnels. It can occur in one or both hands.

Symptoms of carpal tunnel syndrome can include burning, tingling or numbness of the fingers, difficulty gripping tools or other implements, and problems making a fist. Symptoms may appear first at night and are most noticeable in the thumb and the index and middle fingers. People with carpal tunnel syndrome often describe awakening with a tingling sensation and the need to “shake out” the hands to recover normal feeling. There can be pain in the wrist that radiates into the hand or into the forearm. If the condition is not treated, the muscles of the thumb eventually can waste away so that the normal “hill” of muscles at the base of the thumb eventually flattens.

Your doctor will look for decreased feeling in your fingers and for muscle weakness in the affected hand. Your doctor also will check your thumb muscles for signs of wasting and your wrists for signs of arthritis. Your doctor also may look for abnormal accumulation of fluid in several different parts of your body, including your hands, feet and legs, since extra fluid can add pressure in the carpal tunnel.

A wrist examination, looking for arthritis, is an important part of the evaluation. In addition, the examination likely will include maneuvers that test for abnormal nerve function when the pressure in the carpal tunnel is raised. The Tinel’s test is performed by tapping over the median nerve at the wrist. In Phalen’s maneuver, the wrist is flexed for 30 to 60 seconds. In each of these, the development of radiating pain, numbness or tingling suggests compression of the median nerve in the carpal tunnel.

Doctors usually diagnose carpal tunnel syndrome based on your history of hand symptoms and your physical examination. X-rays and other imaging tests are rarely helpful. Your doctor can confirm the diagnosis of carpal tunnel syndrome by ordering nerve tests (called nerve-conduction studies) of the median nerve in your affected hand. These tests are not perfect, however. Some patients have evidence of the syndrome by their symptoms or examination and yet the nerve tests are normal. Your doctor may order blood tests to look for evidence of diabetes or thyroid disease since these are common triggers of carpal tunnel syndrome.

How long carpal tunnel syndrome lasts varies depending on the cause. Sometimes the syndrome comes and goes and does not require treatment. For example, a person whose carpal tunnel syndrome is caused by sports-related overuse may recover quickly with treatment, rest and modified activity. In someone whose carpal tunnel syndrome is caused by chronic arthritis, symptoms may be more stubborn and require longer therapy.

If you type or use a computer keyboard, you can decrease your risk of carpal tunnel syndrome by making sure that you work in a “wrist neutral” position, with the wrist joint straight, not bent up or down. To help you do this, several types of office aids are available, including a cushioned wrist rest and a keyboard tray that adjusts to a position below the work surface. Newer types of keyboards also are being developed, including ones that split the keys into left-hand and right-hand groups, and others that bend the keyboard into a tent shape. You also may need to check the position of your hand when you use a computer mouse and trackballs because some experts suspect that people who use these computer accessories consistently are more likely to develop carpal tunnel syndrome. If you continue to have symptoms, you may want to have a professional assess your workstation.

To prevent sports-related carpal tunnel syndrome, ask your trainer or a sports medicine physician about effective ways to support your wrist during high-risk activities.

In most cases of carpal tunnel syndrome, treatment begins with a wrist splint to be worn mainly at night. Anti-inflammatory medication also may be given to decrease pain and numbness. Injections of cortisone may be given to reduce swelling, but they tend to provide only temporary relief. For patients who do not improve with nonsurgical treatments, surgery can be done to relieve pressure on the median nerve by cutting a ligament at the bottom of the wrist, which creates more room for the nerve in the carpal tunnel.

Call your doctor if you feel pain, tingling or numbness in your fingers that does not go away. If you have trouble grasping objects, making a fist or have weakness in your hand or arm, you should see your doctor.

Most people with carpal tunnel syndrome recover completely with treatment. A small percentage of patients have permanent nerve injury.

Diseases and Conditions Center

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.