Carpal Tunnel Syndrome and Typing Link Disputed

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Carpal tunnel syndrome has been a major workplace issue since the late 1980s when more and more office workers began using computers. A study published in June 2001 in the journal Neurology challenges the widely held belief that prolonged work at computer keyboards is linked to carpal tunnel syndrome. Carpal tunnel syndrome (CTS)is characterized by pain, tingling, and numbness in the wrist and hand. Many people with CTS often awaken during the night with these symptoms which commonly affect the thumb, index, and middle fingers. The problem is due to a decrease in the space between the carpal (wrist) bones and a wrist ligament where the median nerve passes through. Surgery is often used to treat this condition. However, not everyone with such symptoms has CTS, and other methods are also used to treat it. Now researchers at the Mayo Clinic in Scottsdale, Arizona say that computer keyboards do not cause CTS. Dr. Benn Smith, a neurologist, and his colleagues studied 257 office workers who typed between six and seven hours per day. The researchers found that only 27 participants (10.5 percent) had symptoms consistent with CTS confirmed by electrodiagnostic studies. This is approximately the same rate found in the general population. Other factors cited in the development of CTS include people with smaller diameter carpal tunnels, rheumatoid arthritis, diabetes, and pregnancy. Smoking is a major risk factor because it reduces the amount of oxygen available to nerve cells. Obesity, lack of exercise, poor diet, and thyroid disease may also contribute. In a study performed in Sweden two years ago, about 14 percent of nearly 2500 people surveyed reported symptoms of pain, numbness, and tingling in at least two fingers at least twice weekly. Of the 354 people reporting symptoms, 262 were given physical examinations and nerve conduction (NCV, see commentary below) studies. CTS was diagnosed in 94 individuals or approximately 36 percent of those with symptoms. The symptomatic group was compared to a control group of 125 asymptomatic people. In this group, CTS was found in 23 subjects or approximately 18.5 percent, about half the incidence of CTS found in subjects with symptoms. (Reported in Year Book of Rheumatology, Arthritis, and Musculoskeletal Disease, 2001.) COMMENTARY There are many causes of pain and tingling or numbness in the arm and hand. Many people with such symptoms often believe they have CTS, but there are other musculoskeletal problems which can be the cause instead. True carpal tunnel syndrome is best diagnosed by nerve conduction velocity (NCV) testing. This is an electrodiagnostic procedure in which electric sensors attached to the skin (not needles – that is a different procedure call electromyography or EMG) send a current from an area above the wrist to another area below the wrist. The amount of time it takes for the current to reach the target sensor indicates if there is any slowing of nerve conduction speed. If so, this could be caused by pressure on the median nerve at the carpal tunnel. Conditions commonly treated in chiropractic practice which can mimic CTS include myofascial pain syndromes of the neck, shoulder, and back, rib strains, neck and back strains and sprains, osteoarthritis of the spine, and disc herniations. A careful examination should be performed to differentiate CTS from these and other conditions. If there is any doubt as to the diagnosis, NCV testing should be performed. View Article »