USE OF SCREENING NERVE-CONDUCTION STUDIES FOR PREDICTING FUTURE CARPAL-TUNNEL SYNDROME

Objective--To determine if an abnormal sensory nerve conduction study consistent with median mononeuropathy in asymptomatic workers was pred ictive of future complaints of the hand or finger suggestive of carpal tunnel syndrome. Methods--This was a case-control study of over 700 a ctive workers at five different work sites: four sites involved manufa cturing workers and one site represented clerical workers. Patients' r eports of symptoms of pain, numbness, tingling, or burning in the hand or finger that lasted more than one week or occurred three or more ti mes after the initial screening were investigated. 77 cases were defin ed as asymptomatic workers with electrodiagnostic findings of median m ononeuropathy in either hand based on a comparison of median and ulnar sensory evoked peak latencies. A difference greater than or equal to 0.5 ms was defined as abnormal; a normal difference was less than or e qual to 0.2 ms. Controls were asymptomatic age, and sex matched worker s with normal nerve conduction studies in both hands. Follow up questi onnaires were completed 17 (SD 6) months later. Results--The follow up participation rate was 72%. Cases had a 12% risk of developing sympto ms during the follow up period compared with 10% in the control group, chi(2) = 0.12, P = 0.73. Conclusions--Abnormal median sensory nerve c onduction studies in asymptomatic workers were not predictive of futur e hand or fingers complaints and if used for preplacement screening am ong active workers this should be done with caution.