Carpal Tunnel Syndrome Health Article

Definition

Carpal tunnel syndrome is a common disorder caused by compression at the wrist of the median nerve supplying the hand, causing numbness and tingling.

Description

The carpal tunnel is an area in the wrist where the bones and ligaments create a small passageway for the median nerve. The median nerve is responsible for both sensation and movement in the hand, in particular the thumb and first three fingers. When the median nerve is compressed, an individual's hand will feel as if it has "gone to sleep." Persistent pressure causes pain that may manifest as a burning or tingling sensation in the fingers (acroparesthesia). Reduced motor ability in the hand and wrist may gradually develop as well.

Women between the ages of 30 and 60 have the highest rates of carpal tunnel syndrome; they are two to five times as likely as men to develop the disorder. It is the most frequently occurring nerve compression found in the upper part of the body, and is a very significant cause of missed work days. Research has shown that the prevalence of carpal tunnel syndrome in the general population ranges from 2.1 to 4%. At least 200,000 carpal tunnel release surgical interventions are performed every year in the United States, and is the most frequently performed surgery on the hand. The costs associated with the procedure are at least $1 billion each year. The cost to employers is also substantial because of the significant loss of work time associated with the condition.

Causes and symptoms

Compression of the median nerve in the wrist can occur during a number of different conditions, particularly those conditions which lead to changes in fluid accumulation throughout the body. Because the area of the wrist through which the median nerve passes is very narrow, any swelling in the area will lead to pressure on the median nerve. This pressure will ultimately interfere with the nerve's ability to function normally. Pregnancy, obesity, arthritis, certain thyroid conditions, diabetes, and certain pituitary abnormalities all predispose individuals to carpal tunnel syndrome. Other conditions which increase the risk for carpal tunnel syndrome include the presence of organic lesions, tumors, congenital malformations, and various injuries to the arm and wrist (including fractures, sprains, and dislocations). A type of carpal tunnel syndrome that is transmitted by hereditary means has also been found. Furthermore, activities which cause an individual to repeatedly bend the wrist inward toward the forearm can predispose to carpal tunnel syndrome. Certain jobs that require repeated strong wrist motions carry a relatively high risk of precipitating carpal tunnel syndrome. Injuries of this type are referred to as "repetitive motion" injuries, and are more frequent among people working at computer keyboards or cash registers, factory workers, and some musicians.

Symptoms of carpal tunnel syndrome include numbness, burning, tingling, and a prickly pin-like sensation over the palmar surface of the hand, and into the thumb, forefinger, middle finger, and half of the ring finger. Some individuals notice a shooting pain going from the wrist up the arm, or down into the hand and fingers. This pain can radiate into the shoulder, neck, and chest regions, in some cases. Although pain is generally increased during repetitive movement, it is typically greatest during the night. With continued median nerve compression, an individual may begin to experience muscle weakness, making it difficult to open jars and hold objects with the affected hand. Eventually, the muscles of the hand served by the median nerve may begin to grow noticeably smaller (atrophy), especially the fleshy part of the thumb. Untreated, carpal tunnel syndrome may eventually result in permanent weakness, loss of sensation, and even paralysis of the thumb and fingers of the affected hand. Noticeable differences in strength and sensory perception can develop between the affected hand and the unaffected hand.