Effects of occupational use of vibrating tools in the autonomic, central and peripheral nervous system

Abstract

Objectives:The objective of this study was to clarify the autonomic, central and peripheral nervous effects of vibrating-tool operation.

Methods: The ECG R-R interval variability (CV_RR), including the C-CV_HF, C-CV_LF (two component CVs of the CV_RR reflecting parasympathetic and sympathetic activities, respectively) and the power spectral densities (PSD_HF and PSD_LF) after autoregressive analysis, short-latency somatosensory evoked potentials (SSEP), distribution of nerve conduction velocities (DCV), and median and radial nerve conduction velocities (NCVs) were measured in 17 vibrating-tool operators and the same number of age-matched control subjects. Some of the operators complained of white finger even in summer as soon as they arrived at the cold workplace.

Design: The significance of the differences in neurophysiological data between the exposed and unexposed groups and the associations between these data in the former were investigated.

Results: The CV_RR, C-CV_HF and PSD_HF were significantly lower in the vibrating-tool operators than in the matched controls. The N9–N13 interpeak latency of the SSEP, i.e., conduction time of the cervico-spinobulbar pathway, in the operators was significantly prolonged as compared with the controls; the faster velocities of the DCV and the NCVs were significantly slowed in the operators. The N9–N13 interpeak latency in the operators was significantly correlated with the C-CV_HF.

Conclusion: Complex stressors of local vibration, cold, noise and heavy work, seem to affect the cervico-spinobulbar, parasympathetic and peripheral nerve functions. Also, parasympathetic hypofunction may imply a consequence in brainstem pathology induced by cold exposure in addition to vibration.