Carpal tunnel syndrome
The most common of the nerve entrapment syndromes, carpal tunnel syndrome results from compression of the median nerve at the wrist, within the carpal tunnel. This nerve passes through, along with blood vessels and flexor tendons, to the fingers and thumb. Compression neuropathy causes sensory and motor changes in the median distribution of the hand.
Carpal tunnel syndrome usually occurs in women between ages 30 and 60 and poses a serious occupational health problem. Assembly-line workers and packers, secretary-typists, and persons who repeatedly use poorly designed tools are most likely to develop this disorder. Any strenuous use of the hands—ustained grasping, twisting, or flexing—aggravates this condition.
The carpal tunnel is formed by the carpal bones and the transverse carpal ligament. (See Viewing the carpal tunnel.) Inflammation or fibrosis of the tendon sheaths that pass through the carpal tunnel can cause edema and compression of the median nerve.
Many conditions can cause the contents or structure of the carpal tunnel to swell and press the median nerve against the transverse carpal ligament. Such conditions include rheumatoid arthritis, flexor tenosynovitis (commonly associated with rheumatic disease), nerve compression, pregnancy, renal failure, menopause, diabetes mellitus, acromegaly, edema following Colles’ fracture, hypothyroidism, amyloidosis, myxedema, benign tumors, tuberculosis, and other granulomatous diseases. Another source of damage to the median nerve is dislocation or acute sprain of the wrist.