What Is It?
In the wrist, nerves and tendons pass through a space called the carpal tunnel.
Because the carpal tunnel is somewhat narrow, a major nerve called the median 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 show up most in the thumb, index finger, middle finger and half of the ring finger because the median nerve provides sensation to those areas.
Because the carpal tunnel already is narrow, the nerve can become irritated if it narrows even a little more. Injury to the nerve also can cause carpal tunnel syndrome. There are several common causes, including:
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Arthritis or fracture near the wrist
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Pregnancy
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Diabetes
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Overuse (as in typists, cashiers or certain athletes)
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Thyroid disease, particularly an underactive thyroid
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.
