Carpal tunnel syndrome is a disorder caused by compression at the wrist of the median nerve supplying the hand, causing numbness and tingling. The carpal tunnel is an area in the wrist where the bones and ligaments create a small passageway for the median nerve. The median nerve is responsible for both sensation and movement in the hand, in particular the thumb and first three fingers. When the median nerve is compressed, it cannot function normally, and an individual's hand will feel as if it has "gone to sleep."

Because the carpal tunnel is very narrow, any swelling or fluid accumulation in the area will lead to pressure on the median nerve. Pregnancy, obesity, arthritis, certain thyroid conditions, diabetes, and certain pituitary abnormalities may cause carpal tunnel syndrome. Various injuries to the arm and wrist (including fractures, sprains, and dislocations), can also increase the...