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 rep orted by subjects with vibration-induced white finger. Methods: Thermal thr esholds (for perception of heat and cold), vibrotactile thresholds (for per ception of vibration at 31.5 and 125 Hz) and finger systolic blood pressure s were measured in 107 dockyard workers, including 31 controls and 76 worke rs exposed to hand-transmitted vibration (50 reporting finger blanching con sistent with vibration-induced white finger). A history of vibration exposu re and symptoms associated with hand-transmitted vibration were obtained fo r each subject. Results: Increased duration of exposure to vibration result ed in a deterioration of both thermal thresholds and vibrotactile threshold s. Finger systolic blood pressures were lower in subjects reporting finger blanching and were related to the extent of blanching on the measured finge r. Reported sensations of tingling were not correlated with any of the thre shold measures; thermal thresholds and vibrotactile thresholds showed evide nce 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 th resholds. Conclusions: Vascular and neurological signs produced by hand-tra nsmitted vibration can occur independently, but the principal vascular symp tom (i.e. attacks of blanching) and some commonly reported neurological sym ptoms (i.e. sensations of numbness and tingling) may be related.