Thermal thresholds, vibrotactile thresholds and finger systolic blood pressures in dockyard workers exposed to hand-transmitted vibration.

OBJECTIVES

To quantify neurological dysfunction in workers exposed to hand-transmitted vibration using alternative neurological tests. To relate the neurological findings to the results of vascular tests and the symptoms reported by subjects with vibration-induced white finger.

METHODS

Thermal thresholds (for perception of heat and cold), vibrotactile thresholds (for perception of vibration at 31.5 and 125 Hz) and finger systolic blood pressures were measured in 107 dockyard workers, including 31 controls and 76 workers exposed to hand-transmitted vibration (50 reporting finger blanching consistent with vibration-induced white finger). A history of vibration exposure and symptoms associated with hand-transmitted vibration were obtained for each subject.

RESULTS

Increased duration of exposure to vibration resulted in a deterioration of both thermal thresholds and vibrotactile thresholds. Finger systolic blood pressures were lower in subjects reporting finger blanching and were related to the extent of blanching on the measured finger. Reported sensations of tingling were not correlated with any of the threshold measures; thermal thresholds and vibrotactile thresholds showed evidence of deterioration with reports of increasing numbness. Both numbness and tingling were correlated with reports of finger blanching. Finger systolic blood pressures were not correlated with either thermal or vibrotactile thresholds.

CONCLUSIONS

Vascular and neurological signs produced by hand-transmitted vibration can occur independently, but the principal vascular symptom (i.e. attacks of blanching) and some commonly reported neurological symptoms (i.e. sensations of numbness and tingling) may be related.