Electromyography of those exposed to vibration

Electrophysiological findings in the median and ulnar nerves of a group of ten workers who operate hand-held vibrating power tools are described. Motor conduction velocities, motor latencies and amplitude of evoked compound muscle action potentials were measured. We have observed statistically significant changes in the distal latencies and in the amplitude of evoked compound muscle action potentials of median nerves in all the subjects examined, whereas the motor conduction velocities were normal in both median and ulnar nerve. These findings are compatible with functional changes without a clinically manifest neuropathy and they are suggestive of a compression damage such as carpal tunnel syndrome: the possible pathogenic mechanism of these damages are discussed. It's necessary to emphasize the importance of further studies in order to estimate the type and entity of the exposure to vibrations to show a cause-effect relationship.