MedGen

Injury to the median nerve caused by its entrapment at the wrist as it traverses through the carpal tunnel. Clinically, constrictive median neuropathy is characterized by pain, paresthesia, and weakness in the median nerve distribution of the hand. [from HPO]

Carpal tunnel syndrome is a disorder caused by disturbances in nerve function (neuropathy), leading to pain and numbness or tingling (paresthesia) primarily in the wrist and hand. While carpal tunnel syndrome can occur at any age, it most often affects people between the ages of 40 and 60. In more than half of cases, both hands are affected; however, the severity may vary between hands. When only one hand is affected, it is most often the hand used for writing (the dominant hand).

In carpal tunnel syndrome, the pain or paresthesia is usually felt in the wrist, the palm, and the first four fingers of the hand. These signs and symptoms often develop during sleep and are noticeable upon waking. Affected individuals typically shake their hand to get rid of the pain and numbness, a characteristic move known as the flick sign. As the condition advances, the signs and symptoms begin to occur during the day as well. Affected individuals may have difficulty performing manual tasks such as turning doorknobs, fastening buttons, or opening jars. The symptoms of carpal tunnel syndrome may be triggered by certain activities that flex or extend the wrist, such as driving, typing, or holding a telephone.

Over time, people with carpal tunnel syndrome can have muscle and nerve wasting (atrophy) in the affected hand and a reduced ability to detect sensations, which can be mistaken for an improvement of symptoms. [from MedlinePlus Genetics]