The most common symptoms of CTS include numbness, tingling, burning, weakened grip or pain that may extend from the fingers to the shoulder. Symptoms may occur in one or both hands, and frequently occur at night.
In the centre of the wrist there is a space called the carpal tunnel, where a major nerve (the median nerve) and nine tendons pass from the forearm into the hand. The roof of this tunnel is formed by a strong ligament called the transverse carpal ligament.
When there is swelling in the carpal tunnel, pressure builds on the median nerve, which supplies most of the feeling and movement to the fingers and thumb. When pressure becomes great enough to compress the median nerve, CTS may occur.
Swelling in the carpal tunnel may be caused by heredity, diabetes, thyroid problems, fractures or arthritis. Fluid retention during pregnancy may create CTS symptoms, but these symptoms will typically go away after delivery. Repetitive hand motion and activities that involve grasping, squeezing or clipping can make the symptoms worse; but for most people the actual cause is unclear.