To investigate the hand-arm vibration syndrome (HAVS) among symptomatic swagging workers exposed to hand-arm vibration, using medical evaluation and measurement of workplace vibration. Furthermore, to evaluate the neurophysiological.

Four workers showing symptoms relevant to HAVS were evaluated. Medical evaluation consisted of medical interview, questionnaire, nail-bed compression test, and sensory perception tests for vibration and pain. Some other diseases were excluded by a medical interview, hematological assessment, and urinalysis. Cold provocation test was used to assess the peripheral vascular changes, and a nerve conduction velocity (NCV) test was implemented to ascertain the peripheral neural changes. Pegboard, hole plate, and tapping board tests were performed to assess motor nerve function. The hand-arm vibration acceleration levels of the swagging machines were measured. Six months later, follow-up NCV tests were performed.

The actual exposure time to vibration was not longer than 15 minutes per day. The hand-arm vibration acceleration levels of the swagging machines, according to actual exposure time, were from 3.63 to 12.98 m/sec2, by ISO 5349. The vibratory perception thresholds and the recovery time of a nail color following finger cooling were significantly increased in all four workers. The perception of pain was mildly increased. The nerve conduction studies at first diagnosis and follow-up showed multifocal neural impairment caused by vibration. However, we could not rule out the concomitant presence of the carpal tunnel syndrome in one worker.

These results show that HAVS can be caused by hand-arm vibration in swagging workers. Interestingly, the NCV results suggested that vibration-induced neural conduction impairments could vary, and need to be interpreted cautiously.