Vestibular and balance findings in nonsymptomatic workers exposed to styrene and dichloromethane

The aim of our study was to assess the vestibular and balance system in non-symptomatic workers exposed to styrene and dichloromethane at the workplace.

Subjects underwent videonystagmography including saccades, smooth pursuit (SP), optokinetic test (OKN), gaze nystagmus assessment, bithermal caloric test, and static posturography.

Study groups included 74 workers in plastics manufacturing, aged 40 (SD 8) years, exposed to styrene and dichloromethane, and the reference group of 49 non-exposed subjects, aged 36 (SD 10) years.

More than 60% of exposed and non-symptomatic workers revealed abnormal results of vestibular tests. Saccadic latency elongation (p = 0.0098), lower gain in SP (p = 0.0037) and OKN (p = 0.0000) were more common in the exposed group, as well as lower reactivity (p = 0.0337) and mean slow phase velocity of caloric nystagmus. Static posturography revealed higher sway velocities in the test with eyes closed, on foam and worse results of three from five limit of stability tests. No relationship between chemicals exposure and vestibular and balance test results was found.

In principle, our findings indicate the possibility of high-level deficits in the central part of vestibular system. Lower vestibular reactivity may suggest that bilateral vestibular hypofunction might also be the possible consequence of solvent exposure.