Changes over a workshift in aesthesiometric and vibrotactile perception thresholds of workers exposed to intermittent hand transmitted vibration from impact wrenches.
Level 3 - non-randomized controlled study
Non-randomized controlled prospective pre-post study with a concurrent control group
PubMed 9326161 · doi:10.1136/oem.54.8.577
What was done
The study assessed acute changes in tactile perception thresholds across a single workshift in 30 impact wrench users exposed to intermittent hand-transmitted vibration (16 men, 14 women) and 25 control manual workers (10 men, 15 women). Pre- and post-shift measurements included aesthesiometric thresholds (two-point discrimination and depth sense perception) and vibrotactile perception thresholds at 16, 31.5, and 125 Hz to calculate temporary threshold shifts. Hand-arm vibration dose was calculated according to ISO 5349 (mean 8-hour energy-equivalent acceleration, (ahw)eq(8)), and baseline sensorineural disorders were graded using the Stockholm workshop scale.
What was found
Adjusted for age and alcohol consumption, baseline pre-shift vibrotactile thresholds were higher in exposed workers than in controls, with no baseline group differences in aesthesiometric thresholds. Mean daily vibration exposure was estimated at 1.3 m/s² rms. Exposed workers showed significant temporary threshold shifts at all tested frequencies (16, 31.5, and 125 Hz) and a significant increase in depth sense perception thresholds among men; controls exhibited no significant threshold shifts. Vibrotactile temporary threshold shifts correlated positively with shift vibration dose and baseline sensorineural disorder severity (strongest at 125 Hz). No significant relation was found between aesthesiometric changes and vibration dose. Specific numerical threshold shifts and correlation coefficients were not reported in the abstract.
Why it matters
This study shows that acute sensory impairment occurs across a single workshift even under low estimated vibration exposures considered to pose minimal health risk, with temporary threshold shifts tracking both acute vibration dose and underlying sensorineural symptoms.
Limits
The sample size was modest (30 exposed, 25 controls) from a single occupational setting. The abstract does not report exact threshold numbers, standard deviations, or correlation magnitudes. The cross-shift design measures only acute, reversible changes rather than long-term permanent neurological injury.
Cited by
- supports Vibrating tools cause temporary sensory loss in fingertips that completely restores back to normal.