Carpal tunnel syndrome

Alternative names:

median nerve dysfunction

Definition:

A condition that results from compression of the median nerve at the wrist.

Causes, incidence, and risk factors:

Carpal tunnel syndrome is caused by pressure exerted on the median nerve at 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 through a gap formed by the wrist bones (called the carpal bones) and the tough membrane that holds the bones together (the transverse carpal ligament). This gap is called the carpal tunnel. The passageway is rigid, so swelling of any of the tissues in this area can cause compression of the nerve (this is also called entrapment of the nerve).

The condition occurs most often in women 30 to 60 years old, but it also occurs in men and in all age groups. 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 mellitus, 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 injury may be from sports such as racquetball and handball, or from sewing, typing, driving, assembly-line work, painting, writing, use of tools (especially hand tools or tools that vibrate), or similar activities.