Carpal tunnel syndrome Carpal tunnel syndrome (CTS) is the name for a group of problems that includes swelling, pain, tingling, and loss of strength in your wrist and hand. Women are three times more likely to have CTS than men. What is CTS? CTS is the name for a group of problems that includes swelling, pain, tingling, and loss of strength in your wrist and hand. Your wrist is made of small bones that form a narrow groove or carpal tunnel. Tendons and a nerve called the median nerve must pass through this tunnel from your forearm into your hand. The median nerve controls the feelings and sensations in the palm side of your thumb and fingers. Sometimes swelling and irritation of the tendons can put pressure on the wrist nerve, causing the symptoms of CTS. A person's dominant hand is the one that is usually affected. However, nearly half of CTS sufferers have symptoms in both hands. CTS has become more common in the U.S. and is quite costly in terms of time lost from work and ex