Frequent use of a computer keyboard does not pose a major risk for carpal tunnel syndrome, as reported by researchers from the largest study on the topic to date. This directly opposes popular belief since many office workers who use computers are convinced their symptoms are caused by extended time at the keyboard, but smaller studies have shown similar results to that of the current study. Critics say the new study does not account sufficiently for those at higher risk, such as people using a computer for more than 20 hours a week or those with a heavier computer mouse, and people with other computer-related injuries that are not strictly defined as carpal tunnel syndrome. In addition, computer use was only studied over a one-year period of time so as not to necessarily show the potential of long-term effects.

Carpal tunnel syndrome symptoms include finger numbness, tingling, and pain. It is marked by a severe compression of the median nerve in the wrist and is one of the most common surgeries in the U.S. Three of every 10,000 workers were diagnosed in 2001, according to the Bureau of Labor Statistics (BLS), and fewer than 1% of all full-time computer and data processing workers were diagnosed with carpal tunnel syndrome that year. This number is much less than the 12% of meatpackers who received the same diagnosis in 2001. Being female, a smoker, and over the age of 55 puts people at far greater risk than does computer risk, says Robert Szabo, surgeon and professor of the orthopedic surgery at the University of California, Davis, School of Medicine.

Study Conclusions
Danish researchers studied in more than 5,6000 members of a trade union for one year in regards to their use of a keyboard and mouse. At the study beginning and end, participants filled in a questionnaire asking about specific symptoms. Complaints that met a certain frequency and severity were confirmed by an examination.

• In the beginning, 4.8% reported a prevalent tingling and numbness of the wrist, and 1.4% had symptoms at night when many people with carpal tunnel syndrome typically feel increased pain.
  
• A year later, 5.5% reported new or worsened symptoms, and 1.2% had symptoms in the median nerve.
  
• There was a small but significant association between use of a mouse device for more than 20 hours per week and a risk of carpal tunnel syndrome. More Internet functions require mouse clicks so computer users rely on the mouse more than the keyboard. Those at particular risk are workers in design or drafting or who use the Internet for several hours a day.

"Computers causing [carpal tunnel syndrome] was a myth. No science has ever shown that any medical disorders are caused by using a keyboard. This is finally coming out in the mainstream," points out Szabo. He says that the public was told in the 1980's and '90s about the connection between carpal tunnel syndrome and keyboard use, but none of it was backed by science.

The causes of carpal tunnel syndrome have been a topic of hot debate for twenty years since the condition first became widely discussed. Known causes include rheumatoid arthritis, wrist trauma, pregnancy, and diabetes. Initial treatment may entail splints, painkillers, corticosteroids, and exercise to help relieve the pain, a surgeon may cut the band of tissue around the wrist to reduce pressure on the median nerve. Recovery for such a procedure can take months. Some patients never regain full wrist strength.

Experts are not sure how repetitive hand and finger movements on a keyboard or with a mouse affect nerve structure and function, but they do know that carpal tunnel syndrome is predominantly caused by pressure. Gary Franklin, medical director of Washington's state Department of Labor and Industries, explains that people who work with their hands in jobs that require repetition and force (example: lumberyard worker lifting piles of wood) have the highest risk for carpal tunnel syndrome. The next highest risk group is those who use only force regularly on the job. The category with the least risk attached to it is repetition only - computer use falls into this group. According to Franklin, "Just typing does not increase your risk. The force you use on a computer is minimal."

Potential Shortcomings
People who use the computer for over 20 hours a week were not represented in this study. Therefore, "the conclusions you can draw there are pretty limited. What about graphic artists and reporters, who might be exposed to their computers for 20, 30, or 40 hours a week?" asks David M. Rempel, professor of occupational medicine at the University of California, San Francisco, School of Medicine.

Was a year long enough to draw conclusions? "It may be that five years of follow-up would have resulted I more cases of carpal tunnel syndrome," said Franklin. "But because of the length of the study, that data wasn't there." Szabo agrees that this is a shortcoming of the study because, "Your risk of carpal tunnel syndrome increases with age (shown in every study ever done on this) whether you stay on the job or not."

The study did not address a range of other ailments that can result from computer use, such as tendinitis of the wrist and elbow or trapezius muscle strain, oftentimes causing pain and soreness symptoms similar to those of carpal tunnel syndrome. Rempel says that prolonged computer use will cause roughly 10-15% of workers to develop wrist tendinitis; 30% can expect trapezius muscle strain. "All eyes are on carpal tunnel syndrome, but we need to look at the whole gamut of problems that can come from repeated computer use," stresses Rempel.

Source: Washington Post article titled "PC Use Not Key to Pain" by Suz Redfearn, June 17, 2003.