Effects of occupational lead exposure on motor and somatosensory evoked potentials

In order to objectivate the effects of inorganic lead compounds on the nervous system, 17 men occupationally exposed have been recorded for Motor Electric Potentials (MEPs) of the abductor policis brevis muscles with transcranial, cervical root and peripheral electrical stimulations, for Somatosensory Evoked Potentials (SEPs) of median and tibial posterior nerves, and for Electromyography (EMG). Considering each subject, 16 out of the 17 lead exposed ones exhibited electrophysiological abnormalities, occurring at both peripheral and central levels for the somatosensory as well as for the motor systems. As compared to a normal control group, the lead exposed one showed decreased sensory and motor peripheral conduction velocities, increased motor central conduction time, and delayed cortical P22 SEPs component that could be interpreted as a sensory-motor cortical dysfunction. The respective contributions of MEPs and SEPs are compared to clinical, biological and EMG examinations in the evaluation of the neurotoxic effects of inorganic lead compounds.