Carpal tunnel syndrome is pressure on the median nerve — the nerve in the wrist that supplies feeling and movement to parts of the hand. It can lead to numbness, tingling, weakness, or muscle damage in the hand and fingers.

Causes, incidence, and risk factors

The median nerve provides feeling and movement to the “thumb side” of the hand (the palm, thumb, index finger, middle finger, and thumb side of the ring finger).

The area in your wrist where the nerve enters the hand is called the carpal tunnel. This tunnel is normally narrow, so any swelling can pinch the nerve and cause pain, numbness, tingling or weakness. This is called carpal tunnel syndrome.

Carpal tunnel syndrome is common in people who perform repetitive motions of the hand and wrist. Typing on a computer keyboard is probably the most common cause of carpal tunnel. Other causes include:

Sewing
Driving
Assembly line work
Painting
Writing
Use of tools (especially hand tools or tools that vibrate)
Sports such as racquetball or handball
Playing some musical instruments

Symptoms

Numbness or tingling of the palm of the hand

Numbness or tingling in the thumb and next two or three fingers of one or both hands
Pain extending to the elbow
Pain in wrist or hand in one or both hands
Problems with fine finger movements (coordination) in one or both hands
Wasting away of the muscle under the thumb (in advanced or long-term cases)
Weak grip or difficulty carrying bags (a common complaint)
Weakness in one or both hands