Prevalence of Carpal Tunnel Syndrome in a General Population.

Prevalence of Carpal Tunnel Syndrome in a General Population Atroshi I, Gummesson C, Johnsson R, et al (Department of Orthopedics, Hassleholm-Kristianstad Hospital, Kristianstad, Sweden; Lund University, Lund, Sweden; Departments of Orthopedics and Clinical Neuroscience, Division of Neurophysiology, Lund University Hospital, Lund, Sweden), JAMA. 1999;282:153-158.

The purpose of this study was to estimate the prevalence of carpal tunnel syndrome (CTS) in a general population. Three thousand subjects (age range=25-74 years) were randomly selected from the population register in southern Sweden, an area with demographic characteristics comparable to the general population of Sweden.

A comprehensive questionnaire was mailed to the subjects. The questionnaire included medical history, sex, age, handedness, height, weight, social status, education, amount of exercise, smoking habits, employment, and work activities. Questions and whole body diagrams were also included to document pain, numbness, or tingling that had occurred in any body part in the preceding 4 weeks. Two follow-up reminders were sent to those people who did not respond to the initial questionnaire. The return rate was 83%.

Returned questionnaires were reviewed twice by 2 investigators. During these reviews, they identified subjects who, in the 4 weeks preceding the completion of the survey, had experienced pain, numbness, or tingling in 2 or more of the first 4 fingers at least twice a week. These subjects were contacted, and, if they agreed, they underwent a clinical examination by an experienced hand surgeon. Tests performed by the surgeon included a Tinel test, Phalen tests, sensations tests, and thenar muscle strength tests. A diagnosis of CTS was clinically certain if reoccurring nocturnal or activity-related numbness or tingling was found in at least 2 of the first 4 fingers. Subjects with poorly defined parasthesia, whole arm or hand involvement, or chronic pain as the primary complaint were classified as having clinically uncertain CTS. Following clinical examination, all subjects underwent nerve conduction testing. Median nerve distal sensory latency, wrist-palm conduction velocity, and ulnar nerve distal sensory latency were performed by 3 experienced electromyography technicians who were unaware of the results of the clinical exam. Skin temperature was measured before testing and hands were warmed if the skin temperature was less than 30 [degrees] C. Median neuropathy at the carpal tunnel was diagnosed if the measured median-ulnar sensory latency difference was 0.8 ms or longer.

Data were used to calculate the prevalence rates and confidence intervals for the following categories: (1) prevalence of pain, numbness, or tingling in the median nerve distribution, (2) clinically certain CTS, (3) electrophysiologically confirmed median neuropathy, and (4) clinically and electrophysiologically confirmed CTS.

The prevalence of pain, numbness, or tingling in the median nerve was 14.4%. The prevalence of clinically certain CTS was 3.8%, the prevalence of electrophysiological median neuropathy with symptoms was 4.9%, and the prevalence rate for clinically and electrophysiologically confirmed CTS was 2.7%.

A strong association was found between body weight index and the presence of CTS. Of the subjects with clinically and electrophysiologically confirmed CTS, 70% were classified as overweight or obese, based on recorded height and weight and calculation of body weight index. This was a significant difference from the finding that 47% of the respondents without symptoms were overweight or obese. The results also showed that the prevalence of CTS was higher in blue-collar workers than in white-collar workers and greater among workers who reported using excessive force or working in a position of excessive wrist flexion or extension. The male-to-female ratio of the prevalence of CTS was 1:1.4. This ratio increased to almost 1:4 in older women. Medical conditions such as rheumatoid arthritis and diabetes did not show significant associations with CTS.

Compared with other studies, the authors reported that this study showed a higher prevalence of carpal tunnel symptoms in the general population, and they believed that this finding was the result of the use of a large, random sample. The prevalence rate of asymptomatic median neuropathy (18%) was also found to be high, a finding related to the large sample and to the electrophysiological testing technique.

The authors suggested that the prevalence rates calculated in this study will be useful in determining the prevalence of CTS in specific occupational groups. They also concluded that early diagnosis and treatment can be facilitated through the recognition of the prevalence rates.

Nancy R Talbott, PT
University of Cincinnati
Cincinnati, Ohio