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Med. Pr. 2005;56(2)

Distribution of conduction velocity in the ulnar nerve among lead exposed workers

Rozkład prędkości przewodzenia we włóknach nerwu łokciowego u osób zawodowo narażonych na działanie ołowiu

Małgorzata Bilińska1, Jolanta Antonowicz-Juchniewicz2, Magdalena Koszewicz1, Beata Kaczmarek-Wdowiak2, Bogusława Kreczyńska2 1 Z Katedry i Kliniki Neurologii 2 Z Katedry i Kliniki Chorób Wewnętrznych, Zawodowych i Nadciśnienia Tętniczego Krwi Akademii Medycznej we Wrocławiu

Abstract

Background: Neuropathy can be one of the symptoms of the toxic effect of lead on the nervous system. The aim of this work was to perform clinical and neurophysiological assessment of the peripheral nervous system in workers exposed to lead. Materials and Methods: The study included 34 exposed workers and 20 healthy controls. Motor (ulnar, peroneal) and sensory (ulnar, sural) conduction velocity as well as conduction velocity distribution in ulnar n. and EMG from the I. interosseus muscle were assayed. The whole blood value of Pb 400 ľg/l was adopted as a borderline between workers with low and increased blood lead concentrations. The FEP value of 70 ľg/100 ml erythrocytes was the borderline between those without or with biochemical signsof Pb loading. The workers' age and duration of occupational exposure did not differ significantly between the study and control groups. Results: None of the workers showed clinical signs of neuropathy or abnormalities in routine neurographic examination. As compared with controls, a significantly lowered conduction in slow-conducting motor fibers and neurogenic changes in EMG were observed in workers with the whole blood Pb concentration over 400 ľg/l and in workers with FEP level over 70 ľg/100 ml erythrocytes. Conclusion: Neurotoxic effect of Pb on peripheral nerves is manifested by the damage of slow-conducting motor nerves fibers when overt neuropathy is not yet visible.

Key words

occupational exposure, whole blood Pb concentration, free erythrocyte protoporhirin, conduction velocity distribution