鉛取扱い者の末梢神経障害に関する電気生理学的検討

Abstract

In occupational lead poisoning neurological symptoms, especially minor degrees of peripheral nerve damage, seem to be still common, although severe one such as lead palsy is now rare in clinical practice. Neurological and electrophysiological investigations were performed in 59 workers handling lead in 5 factories. The duration of the exposure was from less than one year to 43 years. Their age distribution was 18 to 64 years, with a mean of 38.4 years. Most of them had some of such complaints as joint pain, lumbago, muscle pain, dizziness, fatigue of lower limbs and so forth. Various nerve conduction measurements were done at median and tibial nerve segments of one side for every worker. Routine electromyography revealed neurogenic changes such as slight decrease in NMU, polyphasic potentials and occasional giant spikes in 39 cases. MCV reduced in 6 cases in the median nerve (*) and 2 cases in the tibial nerve. Sensory nerve conduction velocity was reduced in 8 cases in the median nerve. In 2 cases no sensory action potential could be recorded from the median nerve. Mixed nerve conduction velocity was significantly decreased in 11 cases for the median nerve segments (*) and im 9 cases for the tibial nerve segment.The results mentioned above suggested that there was an evidence of abnormality of peripheral nerve functions in the lead workers without marked clinical neurological signs. Besides, present electrophysiological examination revealed moderate disturbances not only of the sensory nerves but of the motor nerves in most cases. There did not appear any association between the electrical findings and urine lead levels or length of exposure to lead. ((*) The meam conduction velocities of both nerves were significantly lower in the group of lead workers as compared with the age-matched control group. p<0.01.)