A study questioning the link between Carpal Tunnel Syndrome and keyboard use recently made news headlines. The authors of the study, conducted at the Mayo Clinic, Scottsdale, Arizona, reported that “the frequency of Carpal Tunnel Syndrome in computer users is similar to that in the general population.” This finding surprised many, and is timely fodder for those opposed to an OSHA ergonomics regulation. To the careful observer, however, the results of this study should not be too surprising. The study provides no evidence to dispute an association between computer work and musculoskeletal disorders. It does, however, bring into question the field of medicine and healthcare professionals’ ability to accurately and consistently diagnose Carpal Tunnel Syndrome.
Carpal Tunnel Syndrome (CTS) has been reported in the popular press for many years, and the medical condition has undeservedly evolved into the “poster child” for occupational ergonomics. CTS is a condition characterized by pain and numbing or tingling sensations and weakness in certain areas of the hand and is caused by compression of the medium nerve in the carpal tunnel at the wrist. Exactly what causes the median nerve compression, and whether the symptoms are always indicative of compression in the anatomical carpal tunnel, continues to be debated.
The Mayo study is interesting and has certain strengths, but it also suffers from many of the same problems that critics of the scientific basis for occupational ergonomics point to. Most significant, this study did not use a control group. The study also used a relatively small number of self-selected subjects, and did not control certain important variables, including workstation design, task or risk factor exposure, and other important factors in the relationship between a worker and a computer workstation. At best, it should be viewed as preliminary. Even though these shortcomings cast a shadow of doubt over the ability to draw reliable, statistically valid, steadfast conclusions, it is still an important contribution to the body of knowledge, and it lends evidence to what many have suspected for some time: clinically diagnosed CTS directly attributable to computer work is not nearly as common as many believed.
The reason for this appears to center on the methods used to clinically diagnose CTS. In the Mayo study, detailed and thorough methods were applied to diagnose CTS. In a typical clinical setting, where a patient may see a family practitioner or company doctor, the methods and abilities to diagnose CTS may be different, and may be subject to the “art of medicine,” and the differing opinions inherent therein. The fact is, many medical practitioners diagnose CTS based on symptoms alone, and never verify their diagnosis with clinical methods like the Nerve Conduction Studies used in the Mayo study.
A careful reading of the Mayo study reveals that 27%, or 70 out of the 214 subjects, actually reported symptoms often attributed to CTS. Therefore, had diagnoses been made on symptoms alone, the results would have shown that 27% of the Mayo computer users had CTS, not the 10.5% that survived the clinical CTS verification regime.
So, what does this mean? It means that 27% of the Mayo study subjects were actually experiencing potential symptoms of musculoskeletal disorders, yet only 10.5% of those were ultimately attributed to CTS. The study makes no mention of what may have caused the symptoms that affected the other 16.5%. Further, this study does little to dispute a connection between computer use and musculoskeletal disorders, but it does bring into question the ability of the medical profession to accurately diagnose Carpal Tunnel Syndrome.
Perhaps the ensuing debate should focus on the field of health care, rather than on occupational ergonomics.