Editor’s note: This is an excerpt from “Carpal Tunnel Syndrome,” by Joseph J. Biundo, MD, and Perry J. Rush, MD. To download the complete fact sheet, visit www.rheumatology.org and click on “Patient Resources” under “Popular Content.”
Carpal tunnel syndrome is possibly the most common nerve disorder experienced today. The carpal tunnel is located at the wrist on the palm side of the hand just beneath the skin surface (palmar surface). Eight small wrist bones form three sides of the tunnel, giving rise to the name carpal tunnel. The remaining side of the tunnel, the palmar surface, is composed of soft tissues, consisting mainly of a ligament called the transverse carpal ligament. This ligament stretches over the top of the tunnel.
The median nerve and nine flexor tendons to the fingers pass through the carpal tunnel. (Flexor tendons help flex or bend the fingers.) When this median nerve in the wrist is compressed (squeezed by swollen tissues, for example), it slows or blocks nerve impulses from traveling through the nerve. Because the median nerve provides muscle function and feeling in the hand, disabling the nerve results in symptoms ranging from mild occasional numbness to hand weakness, loss of feeling and loss of hand function.
Usually, carpal tunnel syndrome affects only one hand, but it can affect both at the same time, causing symptoms in the thumb and the index, middle, and adjacent half of the ring finger. In addition to numbness, those with the syndrome may experience tingling, pins-and-needles sensation, or burning of the hand, occasionally extending up to the forearm.