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Vibration exposure may cause the hand-arm vibration syndrome (HAVS) including digital vasospasm (vibration white fingers; VWF), sensorineural symptoms and/or muscular weakness and fatigue. Neurophysiologic symptoms include numbness and/or tingling, impaired touch sensitivity, impaired manual dexterity and reduced grip strength in the hands.
Methods
The study comprised 108 young male vibration exposed workers (mean-age 22.6 ± 1.0 y) mainly from the machine shop and construction industry. They were compared with 21 male non-exposed referents (mean-age 22.4 ± 0.9 y). All participants completed several questionnaires related to working and medical history, smoking, alcohol consumption, previous and on-going vibration exposure and symptoms of sensorineural disturbances. The neurophysiologic function was checked by the determination of vibration perception thresholds (VPTs) at 31.5 and 125 Hz and by Monofilament tests.
Results
The point prevalences for tingling sensations and numbness in fingers among the exposed workers were 17 % and 8 %, respectively. The symptoms, however, did not interfere with work or leisure activities. The exposed workers showed significantly raised VPTs for 32 Hz in dig 5 (p=0.006), left hand. The other vibration thresholds were of the same magnitude in the two groups. In the exposed group the point prevalences for abnormal monofilament test results were around 45 % in dig 2, bilaterally and about 35 % in dig 5, bilaterally.
Discussion
The fairly short exposure time (mean value 3-4 y) is probably the main reason for the sparse findings as latency time is often longer than a couple of years. The main findings consist of raised VPTs in the left hand among the exposed worker, who also showed a considerable increase of abnormal monofilament test results in dig 2 and 5, bilaterally. Advice on improved work practices and preventive measures to reduce the vibration exposure was given to workers with neurophysiologic symptoms and signs.