Carpal Tunnel Syndrome

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Overview, Causes, & Risk Factors

Carpal tunnel syndrome is common in people who perform repetitive motions of the hand and wrist, such as typing. When the wrist is poorly positioned, there isn't enough space for the median nerve to travel to the hand.

Carpal tunnel syndrome is caused by pressure exerted on the median nerve at the point where it passes through the wrist. The median nerve supplies sensation to the thumb-side of the palm, and to the thumb, index finger, middle finger, and the thumb-side of the ring finger. It also supplies movement to part of the hand.

The nerve enters the hand between the wrist bones (called the carpal bones) and the tough membrane that holds the bones together (the transverse carpal ligament). This space is called the carpal tunnel. Since the passageway is rigid, any swelling in this area can cause compression of the nerve (this is also called entrapment of the nerve).

The condition occurs most often in people 30 to 60 years old, and is five times more common in women than men. Some of the conditions associated with carpal tunnel syndrome include pregnancy, premenstrual syndrome (PMS), and menopause. This is probably because of hormone changes that cause fluid retention and swelling of the tissues.

Other conditions associated with carpal tunnel syndrome include rheumatoid arthritis, renal failure, diabetes, acromegaly, hypothyroidism, multiple myeloma, obesity, recent tuberculosis, fungal infection, and high blood pressure.

Injury or trauma to the area, including (but not limited to) repetitive movement of the wrists, can cause swelling of the tissues and carpal tunnel syndrome. This type of injury may be caused by sports such as racquetball and handball, or occur during sewing, typing, driving, assembly-line work, painting, writing, use of tools (especially hand tools or tools that vibrate), or similar activities.