Median sensory distal amplitude and latency: comparisons between nonexposed managerial/professional employees and industrial workers.

To test for associations between occupation and median nerve dysfunction, measures of median motor and median and ulnar sensory amplitude and distal latency were compared among three populations: control subjects without occupational exposure to highly forceful or repetitive hand exertions (N = 105), industrial workers with hand/wrist symptoms (N = 103), and asymptomatic industrial workers (N = 137). Mean sensory amplitudes were significantly smaller (p < 0.05) and motor and sensory distal latencies were significantly longer (p < 0.001) in the industrial "asymptomatic hand" population compared to the control population. Prolongation of median relative to ulnar latency was significantly longer in the asymptomatic industrial population (p < 0.05). Results were most plausibly explained by differences in checklist identified ergonomic stressors. Median sensory amplitudes were significantly smaller (p < 0.01) and latencies longer (p < 0.05) for industrial workers with exposure to high grip forces compared to those without. Exposure misclassification may have reduced power to detect statistically significant differences between exposed and nonexposed population groups.