Carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is a nerve compression syndrome caused when the median nerve, in the carpal tunnel of the wrist, becomes compressed. CTS can affect both wrists when it is known as bilateral CTS.^[6] After a wrist fracture, inflammation and bone displacement can compress the median nerve. With rheumatoid arthritis, the enlarged synovial lining of the tendons causes compression.^[1][7]

The main symptoms are numbness and tingling of the thumb, index finger, middle finger, and the thumb side of the ring finger, as well as pain in the hand and fingers.^[1] Symptoms are typically most troublesome at night.^[2] Many people sleep with their wrists bent, and the ensuing symptoms may lead to awakening. People wake less often at night if they wear a wrist splint.^[8] Untreated, and over years to decades, CTS causes loss of sensibility, weakness, and shrinkage (atrophy) of the thenar muscles at the base of the thumb. Work-related factors such as vibration, wrist extension or flexion, hand force, and repetitive strain are risk factors for CTS. Other risk factors include being female, obesity, diabetes, rheumatoid arthritis, thyroid disease, and genetics.^[3][5][9]

Diagnosis can be made with a high probability based on characteristic symptoms and signs. It can also be measured with electrodiagnostic tests.^[10]

Injection of corticosteroids may or may not alleviate symptoms better than simulated (placebo) injections.^[11][12] There is no evidence that corticosteroid injection sustainably alters the natural history of the disease, which seems to be a gradual progression of neuropathy.^[11] Surgery to cut the transverse carpal ligament is the only known disease modifying treatment.^[3]