Studies Cast Doubt on Causes of Carpal Tunnel

Risk & Insurance, August, 2001 by Michael Capozzi

New research brings good news to employers concerned with costly workers' compensation claims, lost productivity, and potential ergonomic regulations as a result of carpal tunnel syndrome (CTS), one of the most common repetitive stress injuries. The research attacks the causes and risk factors of CTS and pinpoints what types of jobs are likely to cause the ailment.

The most controversial study comes out of Australia, where occupational therapist Sonja Falkiner's findings were presented by hand surgeon Stuart Myles at the Royal Australasian College of Surgeons conference in Canberra, Australia. Both Falkiner and Myles work at Prince of Wales Hospital in Sydney.

Carpal tunnel syndrome is more likely to be caused by being overweight or by an underlying disease than by a person's job duties, according to Myles. Falkiner's study found that the most likely CTS patient is a woman of menopausal age who is obese, diabetic, and a smoker.

Thousands of workers' compensation claims are being paid unnecessarily, says Myles, giving an example of a 51-year-old administrative assistant who was overweight, had diabetes, arthritis in the base of her thumb, and a family history of CTS.

"This woman had all the factors for the development of carpal tunnel syndrome, and yet she had an accepted workers' compensation claim," Myles says. "In such cases, it was just as likely to be pruning the garden, cleaning the house, or playing a sport that caused the disorder."

"It is offensive and ridiculous that unfit people are demanding government payouts for injuries that are more than likely caused by their general lifestyle, not work," says Myles. "It's only those people who work in cold environments, and those who work in highly forceful and repetitive jobs, such butchers and meat packers, that there may be said to be a cause (relating to work)," he adds.

Another study, published in the June 12 issue of Neurology by J. Clarke Stevens and other researchers at the Mayo Clinic in Scottsdale, Ariz., seems to support this claim, at least partially. The researchers studied 257 Mayo Clinic workers and found that only 10 percent had CTS symptoms. An electromyogram, a device that measures the ability of the nerve to conduct electrical impulses, later found that only 3.5 percent of the workers actually suffered from CTS. Clearly, the researchers were surprised by their findings.

"We had expected to find a much higher incidence of carpal tunnel syndrome in the heavy computer users in our study because it is a commonly held belief that computer use causes carpal tunnel syndrome," says Stevens.

These two studies, however, are hardly the last word on the subject, as numerous other studies and experts hold the opinion that repetitive stress from computer use and other job functions does in fact cause CTS.

For instance, a look at the Mayo Clinic Web site reveals this statement, under the risk factors of CTS subheading: "Although it's not clear which activities can cause carpal tunnel syndrome, if your work or hobbies are hand-intensive, involving a combination of awkward, repetitive wrist or finger motion, forceful pinching or gripping and working with vibrating tools, you may be at higher risk for the condition."

Despite the lack of clear answers, one thing is for certain: the condition is costing U.S. businesses plenty, both in terms of workers' compensation costs and lost productivity. According to the U.S. Bureau of Labor Statistics, 27,900 cases of carpal tunnel syndrome were reported in 1999 (the most recent year for which data is available), with 27 days being the median average for days away from work, the highest among all disabling injuries and illnesses.

With this in mind, employers surely will hold their breath, waiting for the next study to bring more clarity to the subject.