Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy (condition in which a nerve gets pinched) and results from compression of the median nerve in the wrist region. The median nerve provides sensation to the palm side of the thumb, index, middle, and part of the ring finger, and it supplies power to most of the thumb muscles. The median nerve runs down the center of the forearm (thus the name “median” nerve) and passes through the carpal tunnel into the palm. The carpal tunnel is located approximately where the hand meets the forearm and consists of an arch of bones covered by a strong ligament – the transverse carpal ligament (also referred to as the flexor retinaculum). The carpal tunnel is a relatively small space and contains the median nerve and nine tendons that also pass from the forearm into the fingers.
Most commonly, CTS results when the tendons or their lining (the synovium) thicken or the ligament tightens. The space available for the median nerve is reduced, and the median nerve becomes compressed or pinched. This commonly results in numbness, tingling, and pain in the palm side of the wrist and fingers and sometimes thumb weakness. Symptoms may occur only or predominantly at night, but often occur during the day with activities such as gripping a steering wheel, tennis racket, or dumbbell, typing, or holding the wrist in bent positions for long periods of time. The goal of treatment is to reduce the swelling of the tissues within the carpal tunnel or loosen or cut the transverse carpal ligament to make more space for the median nerve. Many cases can be managed nonoperatively with activity modification, splinting, and cortisone injections, but in severe or unresponsive cases release of the transverse carpal ligament (i.e., carpal tunnel release) is necessary to relieve symptoms and prevent further damage to the median nerve.