carpal tunnel syndrome
The most common entrapment neuropathy is median nerve entrapment at the wrist, which typically occurs in the carpal tunnel. This leads to carpal tunnel syndrome (CTS), characterized by wrist and arm pain, as well as hand paresthesia. CTS often affects both hands, but symptoms are usually worse in the dominant hand. It affects about 5% of the U.S. population, with Caucasians at the highest risk and women more commonly affected than men, especially between the ages of 45 and 60.
Carpal tunnel syndrome (CTS) is mainly diagnosed based on clinical findings. While there are many reported causes, most cases are of unknown origin. The typical pathophysiology involves demyelination. When assessing a patient for CTS, electromyography and nerve conduction studies (EMG/NCS) are used to: (a) detect slowing or blockage of median nerve fibers in the carpal tunnel, (b) rule out median nerve issues at the elbow, (c) exclude brachial plexopathy, and (d) eliminate cervical radiculopathy as a potential cause.
However, in about 10%–25% of CTS cases, standard nerve conduction studies may show normal results despite clear symptoms. In these cases, a more sensitive nerve conduction technique may be needed to make a proper diagnosis. These advanced studies compare the median nerve with another nerve in the hand, increasing the diagnostic accuracy from around 75% with standard tests to about 95% with specialized testing.