Carpal tunnel syndrome is a painful illness of the hand and wrist that progresses over time. The condition is caused by a compression of the median nerve, which passes from the forearm into the hand, and is responsible for controlling some of your hand muscles and allowing you to feel sensations with your hand. As the median nerve is squeezed, less blood and nutrients flow to it, causing pain, numbness, and weakness in the fingers and thumb. If the median nerve is compressed for a long period of time, the muscles in the hand that receive signals from the nerve shrink in size due to the lack of stimulation from the nerve. The sooner the pressure on the nerve is relieved, the better the chance for recovery. Carpal tunnel syndrome usually occurs only in adults, and women are three times more likely than men to develop the illness. Those who perform assembly line work are especially at risk.