Neural Conduction Impairment in Forestry Workers Exposed to Vibration and in Lead-Exposed Workers

Vesna Jokić and Srđan Borjanović

Institute of Occupational Health and Radiological Protection, Clinical Centre of Serbia, Belgrade, Serbia and Montenegro

Corresponding author: Vesna Jokić, M.D., Ph.D
    Specialist in Occupational Medicine
    Department of Ecology
    Institute of Occupational Health “Dr. D. Karajović”
    Deligradska 29.
    11000 Belgrade, Serbia and Montenegro
    Fax number: +381 11 643 675
    E-mail: drvesnaj@eunet.yu

CEJOEM 2003, Vol.9. No.1.: 13–22

Key words:
Nerve conduction velocity, vibration syndrome, lead exposure, blood lead concentration, carpal tunnel syndrome

Abstract:
The present study deals with the effects of two different adverse factors, lead and local vibration, on the peripheral nervous system in the upper (median and ulnar nerves), and lower limbs (peroneal and sural nerves). Detailed neurophysiological investigation was performed in 40 chainsaw workers, 26 lead-exposed workers, and 36 healthy male controls. All subjects were screened to exclude polyneuropathy. Measurements of sensory and motor nerve conduction velocities were carried out bilaterally from the median, ulnar, peroneal, and sural nerves. In the chainsaw operators the motor and sensory nerve conduction velocities in several segments of the median nerve were significantly reduced. In the vibration-exposed group, the maximal motor conduction velocity (51.4 ± 5.6 m/s), was significantly lowered in the right and left median nerves (in 27–45% of subjects), compared to that in healthy controls (58.2 ± 6.1 m/s). These results suggest that the exposure to hand-transmitted vibration, in addition to ergonomic inadequacies, can contribute to peripheral nerve disorders occurring in chain saw-operating forestry workers. In the lead-exposed group, slowing sensory nerve conduction velocity (54.0 ± 10.6 m/s) was the most frequent pathological pattern. Abnormalities were observed on the median nerve in 53–57%, and in 53–60% on the ulnar nerve in the lead-exposed subjects. In lead-exposed workers, we observed 50% prolongation of distal motor latencies in the right and left median nerves and 14,3% in the left ulnar nerve. Motor nerve conduction velocities of lead workers have been generally lower, although the means values were within normal limits.

Received: 9 April 2003
Accepted: 19 June 2003

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