Carpal tunnel syndrome
The carpal tunnel is a narrow pathway of ligament and bones (carpal bones) at the base of the hand.
Carpal tunnel syndrome occurs when the nerve, which runs from the forearm into the hand, becomes pressed or squeezed at the wrist. This nerve controls sensations to the palm side of the thumb and fingers (apart from the little finger), as well as the impulses to some small muscles in the hand that allow the fingers and thumb to move.
Sometimes, thickening from irritated tendons or other swelling can narrow the tunnel and causes the median nerve to be compressed. The result may be pain, weakness, or numbness in the hand and wrist, radiating up the arm.
The cause of carpal tunnel syndrome is not clear. It is thought that some inflammation develops in a tendon going through the carpal tunnel that causes swelling. There is little space to expand in the narrow tunnel, and this may lead to pressure on the nearby median nerve.
Inflammation can occur if you excessively use your hand.
Carpal tunnel syndrome is more common in manual workers. It can be hereditary, where a close family member has also had the condition. Bone or arthritic conditions of the wrist such as rheumatoid arthritis or wrist fractures may lead to carpal tunnel syndrome.
Other conditions associated with carpal tunnel are: pregnancy, obesity, an under active thyroid, diabetes, the menopause and rare diseases, and it can also be a side effect of some drugs.
Rare causes include cysts, growths, and swellings coming from the tendons or blood vessels passing through the carpal tunnel.
