What is carpal tunnel syndrome?

Carpal tunnel syndrome is a specific group of symptoms that can include tingling, numbness, weakness, or pain in the fingers, thumb, hand, and occasionally in the arm. These symptoms occur when there is pressure on the median nerve within the wrist.

The carpal tunnel is a small space or "tunnel" in the wrist formed by the wrist bones (carpal bones) and a ligament (transverse carpal ligament). The median nerve and several tendons pass through the carpal tunnel from the forearm to the hand. The tendons are surrounded by tubes of tissue (tendon sheaths). The median nerve controls some movements of the thumb, and this nerve supplies feeling to most of the thumb and to the index finger, middle finger, and part of the ring finger.

What causes carpal tunnel syndrome?

Carpal tunnel syndrome is caused by conditions and activities that put pressure on the median nerve and decrease its blood supply, leading to tingling, numbness, pain, and/or weakness. Any of the following conditions or activities, or a combination of them, can lead to carpal tunnel syndrome:

• Conditions such as hypothyroidism and rheumatoid arthritis can increase the amount of tissue in the carpal tunnel. The swelling that is common in pregnancy can also crowd structures in the tunnel.
• Wrist injuries, bone spurs, or swelling of the tendon sheath can decrease the space available in the carpal tunnel. A common cause of tendon sheath swelling is forceful or repetitive movement of the fingers and hand, especially if the wrist is in an awkward position.
• Conditions such as diabetes, which increases nerve sensitivity, can make the median nerve more sensitive to pressure.
• Smoking and obesity can each increase the risk of developing symptoms.

When compared with other illnesses and injuries, carpal tunnel syndrome is one of the most common causes of absence from work.

What are the symptoms of carpal tunnel syndrome?

The most common symptoms of carpal tunnel syndrome are tingling, numbness, weakness, or pain of the fingers or, less commonly, the palm. Symptoms most often occur in the parts of the hand supplied by the median nerve: the thumb, index finger, middle finger, and half of the ring finger. If your little finger is not affected, this may be a sign that the condition is carpal tunnel syndrome, because the little finger is usually controlled by a different nerve than the thumb and other fingers. You may first notice symptoms at night, and you may be able to get relief by shaking your hand.

How is carpal tunnel syndrome diagnosed?

Carpal tunnel syndrome is diagnosed based on your medical history, a physical exam, and sometimes further tests. In learning about your medical history, your health professional will want to know about health conditions you have, such as arthritis, hypothyroidism, diabetes, or pregnancy. He or she will ask about any accidents or injuries of the wrist, arm, or neck you may have had recently. Your usual daily activities and any recent unusual activities are also an important part of your medical history.

Your physical examination will include evaluation of the feeling (sensation), strength, and appearance of your neck, shoulders, arms, wrists, and hands.

Your health professional may recommend further tests. These can include:

• Blood tests, if any health conditions are thought to be contributing to your symptoms.
• Nerve testing to determine whether signals are passing normally down the median nerve.
• X-rays to help evaluate the size and shape of the carpal tunnel or, in some cases, to evaluate your neck.

How is carpal tunnel syndrome treated?

Nonsurgical treatment usually relieves the pressure and pain in the wrist and hand. Mild carpal tunnel syndrome is often treated first by changing the way you do things. If an activity seems to be aggravating your symptoms, you can try doing it less often, increasing the amount of rest time between repetitions, or changing the position you are using for the activity. You may also want to get a wrist brace that keeps your wrist straight and wear it at night. Stretching and strengthening your hands and arms may also help. If your symptoms have continued through a few weeks of home treatment or are more severe, you may require treatment by a health professional. Treatment may need to include medication or care for an underlying condition that is contributing to your carpal tunnel syndrome symptoms.

Surgery is an option for treating carpal tunnel syndrome. However, it is usually reserved for carpal tunnel syndrome that is disabling and that hasn't responded to weeks of treatment. Surgery involves cutting the ligament that forms the roof of the carpal tunnel, which makes more room in the tunnel and relieves pressure on the median nerve. The surgery (carpal tunnel release) is usually successful but in some cases does not completely relieve the numbness or pain. The earlier your condition is diagnosed, the better your chances of relieving the symptoms and preventing permanent damage to the median nerve.

How can I prevent carpal tunnel syndrome?

The first line of defense against carpal tunnel syndrome is to take care of your basic health-maintain a healthy weight, don't smoke, and exercise to maintain your strength and flexibility. If you have chronic conditions such as arthritis or diabetes, follow your health professional's advice for keeping your condition under control. In addition, try to keep your wrists in a neutral position during repetitive or stressful hand activities. (Your wrist is generally in a neutral position when you hold a glass of water.) If you begin to notice signs of carpal tunnel syndrome, stop or reduce any activity that stresses your fingers, hand, or wrist, or try changing the way you do that activity.