CARPAL TUNNEL SYNDROME

Carpal tunnel syndrome is a common painful disorder caused by compression of the median nerve between the carpal ligament and other structures within the carpal tunnel (entrapment neuropathy). The volume of the contents of the tunnel can be increased by organic lesions such as synovitis of the tendon sheaths or carpal joints, recent or malhealed fractures, tumors, and occasionally congenital anomalies. Even though no anatomic lesion is apparent, flattening or even circumferential constriction of the median nerve may be observed during operative section of the ligament. The disorder may occur in pregnancy and is seen in individuals with a history of repetitive use of the hands, and it may follow injuries of the wrists. A familial type of carpal tunnel syndrome has been reported in which no etiologic factor can be identified.

Carpal tunnel syndrome can also be a feature of many systemic diseases: rheumatoid arthritis and other rheumatic disorders (inflammatory tenosynovitis); myxedema, amyloidosis, sarcoidosis, and ieukemia (tissue infiltration); acromegaly; hyperparathyroidism, hypocalccmia, and diabetes mellitus.

Clinical Findings

Pain in the distribution of the median nerve, which may be burning and tingling (acroparesthcsia), is the initial symptom. Aching pain may radiate proximally into the forearm and occasionally proximally to the shoulder, neck, and chest. Pain is exacerbated by manual activity, particularly by extremes of volar flexion or dorsiflexion of the wrist. It may be most bothersome at night. Impairment of sensation in the median nerve distribution may not be apparent. Subtle disparity between the affected and opposite sides can be demonstrated by requiring the patient to identify different textures of cloth by rubbing them between the tips of the thumb and the index finger. Tinel's sign (tingling or shocklike pain on volar wrist percussion) may be positive. Muscle weakness or atrophy, especially of the abductor pollicis brevis, appears later than sensory disturbances. Useful special examinations include electromyography and determinations of segmental sensory and motor conduction delay. Distal median sensory conduction delay may be evident before motor delay.

Differential Diagnosis

This syndrome should be differentiated from other cervicobrachial pain syndromes and from compression syndromes of the median nerve in the forearm or arm. When left-sided, it may be confused with angina pectoris.

Treatment

Treatment is directed toward relief of pressure on the median nerve. Conservative treatment usually relieves mild symptoms of recent onset. When a primary lesion is discovered, specific treatment should be given. When soft tissue swelling is a cause, elevation of the extremity may relieve symptoms. Splinting of the hand and forearm at night may be beneficial, When nonspecific inflammation of the ulnar bursa is thought to be a cause, injection of corticosteroids into the carpal tunnel may be helpful.

Operative division of the volar carpal ligament gives lasting relief from pain, which usually subsides within a few days. Muscle strength returns gradually, but complete recovery cannot be expected when atrophy is pronounced.

Pain guide