ESTIMATING THE PREVALENCE OF DELAYED MEDIAN NERVE-CONDUCTION IN THE GENERAL-POPULATION

objectives of this study were to determine the point prevalence of neu rophysiologically defined median nerve compression and associated carp al tunnel syndrome in a random sample of the general population. The d esign was a two-stage screening study: (i) a cross-sectional survey to estimate the point prevalence of current hand symptoms; (ii) nerve co nduction testing of the median nerve in weighted samples of the survey respondents. The target study population was a random sample of 1000 adults aged between 18 and 75 yr registered with a family practice in the UK. A mailed questionnaire enquired about hand symptoms on the day and included various demographic questions. Weighted random samples w ere taken based on the hand symptoms reported, and the subjects were i nvited to attend for motor and sensory median nerve conduction testing . A neurophysiological diagnosis of median nerve compression was made based on a number of different cut-offs using published criteria. Of t hose receiving a questionnaire, 79% responded. A total of 250 responde rs were invited to attend for nerve conduction testing, of whom 155 (6 2%) attended. Non-response to the questionnaire and non-attendance for nerve conduction testing may have biased the prevalence estimates. Af ter adjustment for such biases, a prevalence estimate of between 7 and 16% was obtained, varying with the different cut-offs used to define delayed median nerve conduction. Subjects over 54 yr of age had a high er prevalence than younger participants. There was no difference in pr evalence estimates between men and women. The conclusion reached was t hat carpal tunnel syndrome, as assessed by delayed median nerve conduc tion, is common in the general population.