Age and weight effects on motor nerve conduction time measurements in an asymptomatic industrial population

Motor conduction delay has been demonstrated in patients with carpal tunnel syndrome (CTS), however, there is also evidence that conduction slowing can be effected by other factors, e.g., the aging process. Recent development of the digital electroneurometer, a hand-held, battery-powered device for measuring motor nerve conduction time, has made this test available for CTS screening in industry. A cross-sectional study of 77 industrial workers was performed to determine the relationship between median motor nerve conduction time at the carpal tunnel and select personal factors. Motor nerve conduction time increased with age, length of employment, and weight. However, these variables accounted for only 20.3% of the variance in conduction time. The study indicates users of this device should be aware of these effects, and that other sources of variation must be identified and controlled if motor nerve conduction tests are to be used for CTS screening in industry.