Definition of Carpal tunnel syndrome:

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.

See also: Carpal tunnel release

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

The condition occurs most often in people 30 to 60 years old, and is more common in women than men.

A number of medical problems are associated with carpal tunnel syndrome, including:

• Bone fractures and arthritis of the wrist
• Acromegaly
• Diabetes
• Alcoholism
• Hypothyroidism
• Kidney failure and dialysis
• Menopause, premenstrual syndrome (PMS), and pregnancy
• Infections
• Obesity
• Rheumatoid arthritis, systemic lupus erythematosus (SLE), and scleroderma