Heavy keyboard use won't trigger carpal tunnel woe

By Anne Harding

NEW YORK (Reuters Health) - People who spend much of their work time typing on a computer keyboard are actually less likely to develop carpal tunnel syndrome than those who spend less time working on a computer, researchers from Sweden have found.

"Although carpal tunnel syndrome is sometimes work-related and ... risk factors probably include certain occupational activities, we are quite confident now that computer use is not one of these," Dr. Isam Atroshi of Hassleholm Hospital told Reuters Health.

In carpal tunnel syndrome, the median nerve that runs from the forearm to the hand becomes compressed at the wrist, leading to weakness, pain and numbness. While computer use is frequently mentioned as a cause of the condition, most research on the issue has focused on specific occupations, rather than the population at large, Atroshi and his team note in the medical journal Arthritis & Rheumatism.

To see if heavy keyboard use does in fact lead to carpal tunnel syndrome in the general population, the researchers surveyed 2,465 people between 25 and 65 years old, dividing them into four groups based on the hours they spent using a keyboard daily.

Among the heaviest keyboard users, who spent four or more hours a day on the computer, 2.6% had carpal tunnel syndrome, compared to 2.9% of those who used computers for one to four hours daily, 4.9% for people with less than an hour of computer time daily, and 5.2% for people who didn't use a computer at all.

The findings suggest that "as far as carpal tunnel syndrome and work are concerned, other hand activities are more important than computer use," Atroshi said.

Typing could actually be protective, he and his colleague suggest, because this type of low-force muscle activity may reduce the risk of swelling and subsequent pressure on the nerve. Activities that do lead to carpal tunnel typically involve repetitive wrist motion and forceful use of the hand, which computer use usually does not require, Atroshi noted.

SOURCE: Arthritis & Rheumatism, November 2007.