The reported incidence of work-related carpal tunnel syndrome has skyrocketed; however, many cases have an underlying systemic cause. A methodical investigation--including appropriate imaging studies and laboratory testing--can differentiate symptoms that are primarily occupational from those with associated medical illness or obesity. Syndrome Defined
A syndrome is a constellation of signs and symptoms useful in establishing a differential diagnosis and pointing the physician in the direction of an appropriate management plan. In the case of carpal tunnel syndrome (CTS), however, this definition is often forgotten. Indeed, clinical features suggestive of median nerve entrapment are often managed as a single entity that is assumed to have a clear, recognized etiology. Exhaustive research by George S. Phalen in the 1950s and 1960s, and others since then, has demonstrated that many common systemic conditions (e.g., diabetes mellitus, thyroid disease, rheumatoid arthritis, osteoarthritis of the wrist, gout, obesity, and even pregnancy) may provoke symptoms of hand pain, numbness, burning, or tingling with or without the additional impact of work-related trauma. Yet in today's medical climate, there is often a rush to judgment. Patients presenting with hand symptoms may be incorrectly diagnosed as having CTS caused by conditions in the workplace. Claims Skyrocketing
Since 1985, when the U. S. Occupational Safety and Health Administration (OSHA) accepted that there were "traumatogens" in the workplace and demanded that repetitive motion disorders be reported, the recorded incidence of cumulative trauma disorders has skyrocketed. About 277,000 cases were reported in 1997, compared with fewer than 50,000 in 1985.CTS has been the fastest growing category, recently accounting for more than 40% of all work-related disabilities. An estimated 26,000 CTS patients in the United States undergo surgical decompression each year. Median time lost from work is about 32 days per patient, more than for any other cause, including back pain. Why so Much Lost Time?
Undoubtedly, one reason why so much work time is lost is that treatment is often unsuccessful. Many patients either do not have CTS or have CTS as part of another, undiagnosed medical condition that accounts for most of the problem. The underlying condition usually is never addressed, largely because our workers' compensation system provides such powerful incentives for declaring any median nerve disorder to be job-related. In Nevada, for example, even a successfully treated case of occupational CTS may merit a permanent partial disability award of $25,000 or more. Since many patients presenting with hand symptoms are poorly paid factory or farm workers with no group health insurance, workers' compensation may represent their only hope of getting treatment. Consequently, the patient may file a claim even when the physician suspects that the real problem lies elsewhere. Patients who do not respond to basic measures such as splinting and anti-inflammatory medication ultimately may undergo decompression surgery--at considerable expense to employers and taxpayers. Causation Issues
Following on the work of Phalen, a number of investigators have suggested that occupation is more likely to be an aggravating factor than the primary cause of CTS. When Peter A. Nathan and Richard C. Keniston studied cohorts of workers' compensation patients, industrial workers, and control populations in both the US and in both the United States and Japan, they found that variables such as age, obesity, wrist dimensions, and physical inactivity were stronger risk factors for CTS than workplace factors such as repetitious or forceful hand use.John R. Schottland and colleagues determined that median nerve conduction latencies were no different among poultry processing workers than among candidates applying for their same type of jobs. Nortin M. Hadler surveyed the world literature on the subject and concluded that all of the major studies describing a cause-and-effect relationship between work and CTS were seriously flawed. These are many compelling reasons to question the validity of a CTS diagnosis being attributed to work related causes. For more information visit www.MedicalSystemsUSA.com
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