Surprising even the researchers themselves, a new study from Mayo Clinic found that heavy computer use, even up to seven hours per day, did not increase a person''s risk of carpal tunnel syndrome (CTS).
The results of the research, published in the June 12 issue of Neurology, indicated that only 10.5 percent of the 257 study participants, all of whom used computers extensively, met clinical criteria for CTS.
"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," said Dr. J. Clarke Stevens, a neurologist at Mayo Clinic in Rochester, Minn., and lead author of the study. "The other finding was that among our cases of carpal tunnel syndrome, two-thirds of them had very mild carpal tunnel syndrome. Our study results were unexpected."
This is the first major study to consider the association between the syndrome and computer usage.
Most of the studies showing that repetitive motion causes CTS involve workers in meatpacking plants or other industrial jobs, not computer users.
"The findings are contrary to popular thought, but nobody has studied the problem carefully," said Stevens. "There has been very little formal study of carpal tunnel syndrome in computer users, and there is not much to find in the literature on this topic. We studied computer users because though there is a commonly held notion that using a computer causes CTS, there really have been few studies published that looked at this in a scientific way."
Stevens offered a message of relief for those who may have wondered about their risks of the so-called "office plague" due to long hours spent in front of a computer.
"I''d like computer users to know that prolonged use of a computer does not seem to lead to carpal tunnel, at least not in our employees who used computers up to seven hours per day," said Stevens. Carpal tunnel syndrome is a common condition in the population, however, which means that some computer users will develop carpal tunnel syndrome. Our study suggests, however, that the risk of developing the syndrome is not increased by working at a computer."
Stevens indicates that though computer use may not be as highly associated with CTS as thought, it is associated with numerous other medical issues. "Carpal tunnel syndrome in computer users has been thought of as a repetitive motion disorder, and it has been assumed that computer use might cause carpal tunnel syndrome as part of such a disorder. People who use the computer do get a lot of other aches and pains in the neck, shoulder, arm and wrist, but most of them do not get carpal tunnel syndrome from using a computer."
As CTS is not the only ergonomics issue related to computer usage, a correct office setup still has great merit, according to Stevens.
"The question arises as to whether ergonomically correct work stations are important," he said. "I think they continue to be very important, because there are a variety of aches and discomfort that can result from using a computer. A majority of the computer users in our study, including those without carpal tunnel syndrome, had experienced neck and upper extremity pain during the two years prior to the study. "What we are saying is that at least in our employees studied, computer use did not seem to increase the risk of getting carpal tunnel syndrome."
There are a variety of factors that do contribute to CTS, according to the study authors.
"The major risk factors for developing carpal tunnel syndrome are being female and middle-aged," said Stevens. "There are many other causes of carpal tunnel syndrome, such as wrist trauma, diabetes, rheumatoid arthritis and pregnancy."
Repetitive motions in industries outside the office also have been linked to CTS, Stevens noted.
"There is certainly a whole variety of other jobs that are much more labor-intensive that we think might cause carpal tunnel syndrome, such as working in a meat packing plant or using a jackhammer," said Stevens. "There have been a number of studies of factory workers and people in packing plants that suggest that type of repetitive motion does seem to be associated with carpal tunnel syndrome."
Though the Mayo Clinic study authors consider their study to be an important first step in studying CTS and computer use, they would like to see further research conducted on the topic.
"I think the study needs to be confirmed by other centers, possibly with a larger number of computer users," said Stevens. "I think more study is needed of this question."
For those who suspect that they may have problems in their hands, Stevens suggests consulting one''s family physician first, who would then make a decision about obtaining nerve conduction studies or perhaps refer to a hand clinic or surgeon for further evaluation.
Research suggests that one person in 10 will develop symptoms of CTS over a lifetime.
CTS is a compression of the median nerve at the wrist, leading to numbness tingling and pain in the hand.
The median nerve passes through the carpal tunnel at the wrist and into the palm where it sends branches that control feeling to the thumb, index, middle and part of the ring fingers.
CTS is treated by wearing a splint at night to reduce waking up or by an injection of cortisone to reduce swelling.
If these measures are not successful, carpal tunnel release surgery, which sections the tough transverse carpal ligament and relieves pressure on the median nerve, may be performed.
by Virginia Sutcliffe