MEDIAN MONONEUROPATHY AMONG ACTIVE WORKERS - ARE THERE DIFFERENCES BETWEEN SYMPTOMATIC AND ASYMPTOMATIC WORKERS

The objective was to determine whether symptomatic workers with an abn ormal sensory nerve conduction study consistent with carpal tunnel syn drome differed, in terms of electrophysiologic measures, psychosocial, demographic, anthropometric, or ergonomic variables, from workers wit h an asymptomatic median mononeuropathy. This was a cross-sectional st udy of active workers at six different work sites. Cases were defined as workers with electrodiagnostic findings of a median mononeuropathy in either hand based on a 0.5-msec prolongation of the median sensory evoked peak latency compared to the ulnar latency. This group was stra tified on the basis of symptoms of numbness, tingling, burning or pain in the hand. The two groups were compared in terms of demographic, an thropomorphic, psychosocial. electrophysiologic, and ergonomic risk fa ctors. Active workers from six different sites were tested; Jive sites involved manufacturing workers, and one site represented clerical wor kers. One hundred eighty-four active workers with a median mononeuropa thy were documented on nerve conduction studies. These workers represe nted a subset of more than 700 workers screened at six different locat ions. The main outcome measure was the patient's report of symptoms of pain, numbness, tingling or burning in the hand or fingers that laste d more than 1 week or occurred three or more times at the initial scre ening. Workers with a median mononeuropathy who complained of hand sym ptoms were more likely to be female, to have jobs with higher hand rep etition levels, to have higher ratings of job security, not to have a history of diabetes, to use more force in their job with more abnormal postures of their wrist and fingers, and to have a trend toward a mor e prolonged median sensory distal latency Most logistic regression mod els explained less than 15% of the variance (pseudo R-2). Women with j obs that have higher ergonomic risks and no history of diabetes were m ore likely to have reported symptoms associated with carpal tunnel syn drome compared to other workers with a documented median mononeuropath y. Psychosocial variables were not particularly discriminatory. None o f the models allows enough precision to predict on an individual basis . (C) 1998 Wiley-Liss, Inc.