Causes

Biologic Causes. Carpal tunnel syndrome (CTS) is considered an inflammatory disorder caused by repetitive stress, physical injury, or medical conditions.It is often very difficult, however, to determine the precise cause of carpal tunnel syndrome. No tests that can identify a specific cause are available. Except in patients with certain underlying diseases, the biologic mechanisms leading to carpal tunnel syndrome are unknown. Although an overactive immune response that causes inflammation and damage in the joints or muscles is responsible for a number of arthritic conditions, similar problems are not likely to play an important role in CTS. More likely, reduced blood flow and lack of oxygen are important in the process leading to progressive swelling and scarring.

Working Conditions versus Medical Problems. Although studies suggest that more than half of CTS cases are associated with workplace factors, there is no strong evidence of a causal relationship. In fact, most studies now strongly suggest that carpal tunnel syndrome is primarily associated with medical or physical conditions, such as diabetes, osteoarthritis, hypothyroidism, and rheumatoid arthritis. It generally tends to occur in such people with certain genetic or environmental risk factors, such as obesity, smoking, alcohol abuse, or significant mental stress. When such susceptible people are then subjected to repetitive hand or wrist work, the risk for CTS can become significant. CTS, then, is very likely to be due to convergences of factors that lead to nerve damage in the hand.

Work-Related Issues and Carpal Tunnel Syndrome

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Worker's Compensation and CTS. The issues surrounding workmen's compensation are particularly troubling in determining accurately whether labor conditions cause carpal tunnel pain. CTS is a major contributor to workmen's compensation cases.

• It is in the employer's interest to seek medical causes for hand and wrist pain, which are not covered by compensation costs. Although some patients will falsify their symptoms in order to acquire workmen's compensation benefits, one study demonstrated that, in general, workers whose employment made them eligible for benefits reported their disabilities just as accurately as those without the possibility for compensation. Workers with CTS who are not granted compensation may remain on the job in spite of significant pain, thereby working inefficiently and possibly endangering themselves.
• It is in the employee's interest to relate the pain to the job so that the leave time is covered by worker's compensation. Some studies, in fact, suggest that workers receiving compensation for CTS stay off the job longer than those who are not being compensated, particularly if the employer is contesting the case.