The carpal tunnel is a space in the wrist through which nerves and tendons pass. Because it is on the narrow side, a nerve called the median nerve that passes through the carpal tunnel 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. It can occur in one or both hands.
Anything that narrows the carpal tunnel can compress the median nerve. Injury to the nerve also can cause carpal tunnel syndrome. Common causes include:
- a fracture near the wrist
- overuse (as in typists, cashiers, line workers, or certain athletes)
- thyroid disease, particularly an underactive thyroid
Sometimes carpal tunnel syndrome occurs without a clear reason.
How long carpal tunnel syndrome lasts depends on the cause. Sometimes it comes and goes and doesn't need to be treated. Carpal tunnel syndrome caused by overuse may recover quickly with treatment, rest, and changes in use of the hands and arms. Carpal tunnel syndrome caused by arthritis might be more stubborn and require longer therapy.
Symptoms of carpal tunnel syndrome include:
- burning, tingling, or numbness in the fingers
- difficulty gripping and holding tools, pens, eating utensils, and other objects
- problems making a strong fist
Symptoms are usually most noticeable in the thumb and in the index and middle fingers. There can be pain in the wrist that extends into the hand or forearm. If the condition is not treated, the muscles of the thumb can waste away so that the normal mound of muscles at the base of the thumb eventually flattens.
Carpal tunnel syndrome is usually diagnosed based on your description of your symptoms and a physical examination. Your doctor will check you for decreased feeling in your fingers, muscle weakness in the affected hand, and signs of arthritis. He or she may also check whether fluid is accumulating in several different parts of your body, including your hands, feet, and legs, since extra fluid can add pressure in the carpal tunnel.
Several tests can help with the diagnosis:
- Tinel's test is done by tapping the skin over the median nerve at the wrist.
- Phalen's maneuver flexes the wrist for 30 to 60 seconds.
If pain, numbness, or tingling develop during these tests, the median nerve in the carpal tunnel may be compressed.
X-rays and other imaging tests rarely help.
In some cases, tests of the median nerve in the affected hand can help make the diagnosis.
Your doctor may also recommend that you have blood tests to look for evidence of diabetes or thyroid disease, since these are common triggers of carpal tunnel syndrome.
Wearing a splint on the affected wrist is often the first place to start.
Taking a nonsteroidal anti-inflammatory drug such as aspirin, ibuprofen (Advil, Motrin, and others), or naproxen (Aleve, Naprosyn, others) can help decrease pain and numbness and reduce inflammation. Acetaminophen (Tylenol) may also be effective.
Injections of cortisone may help reduce swelling, but they tend to provide only temporary relief.
If splints or medications don't help, surgery can relieve pressure on the median nerve. This is done by cutting a ligament at the bottom of the wrist, which creates more room for the nerve in the carpal tunnel.
Most people with carpal tunnel syndrome recover completely with treatment. A small percentage have permanent nerve injury.
If you type or use a computer keyboard, working in a "wrist neutral" position can decrease your risk of carpal tunnel syndrome. This means typing with the wrist joint straight, not bent upward or downward.
Several types of office aids are available, including cushioned wrist rests and keyboard trays that adjust to the correct position for your hands. New keyboard and mouse designs may also help.
Other things you can do include:
- Go easy. Try to use less force when you hit the keys on a keyboard or do other manual tasks.
- Take a break. Every 15 minutes or so, stop typing or doing other activity with your hands. Gently stretch your hands and wrists.
- Stand up straight. Hunching over shortens the muscles in your neck and shoulders. This puts pressure on the nerves in your neck, which can affect the nerves in your wrists, fingers, and hands.
To prevent sports-related carpal tunnel syndrome, ask your trainer or a sports medicine physician about effective ways to support your wrist.