PREVALENCE OF ABNORMAL MEDIAN NERVE-CONDUCTION IN APPLICANTS FOR INDUSTRIAL JOBS

There has been much debate regarding the work relatedness of carpal tu nnel syndrome (CTS) and whether workers diagnosed with CTS had pre-exi sting disease at the time they were hired. To elucidate the latter iss ue, we examined the prevalence of abnormal median nerve conduction wit hin the carpal tunnel in applicants for industrial jobs. Nerve conduct ion studies (NCS) were performed on both hands of 1,021 applicants fol lowing a conditional offer of employment. Each applicant completed a s elf-administered symptom survey specific to the upper extremity. Appli cants had worked previously for an average of 4.4 (range 0-33) years a nd had a mean age of 30.1 (S.D. 8.9) years. Nerve conduction studies w ere performed in a private medical clinic. Sensory palmar latencies we re determined over an 8 cm segment for the median and ulnar nerves. Th e difference between the median and ulnar sensory latencies was the pr imary electrophysiologic measurement used to determine median neuropat hy. Using a very conservative criterion for abnormal median nerve cond uction, 17.5% of the applicants were classified with neuropathy in at least one hand. Despite the relatively high prevalence of median neuro pathy, relatively few (10%) with positive NCS acknowledged symptoms as sociated with CTS. Males had a higher percentage of median neuropathy than did females. We conclude that a large percentage of industrial wo rkers have objective evidence of abnormal median nerve conduction with in the carpal tunnel when hired The high prevalence of abnormal median nerve conduction without corresponding symptoms may suggest a subclin ical entity associated with CTS. (C) 1996 Wiley-Liss, Inc.