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Visual evoked potentials in workers with chronic solvent encephalopathy
Maarten M Verberk1, Joke T Brons, Herman J A Sallé
1Coronel Institute for Occupational and Environmental Health, Academic Medical Centre, University of Amsterdam, Meibergdreef 15, Amsterdam, The Netherlands. M.M.Verberk@amc.uva.nl
Summary
Low-contrast visual evoked potentials (VEPs) reveal reduced contrast sensitivity in solvent-exposed workers, indicating neurophysiological changes. This suggests incorporating low-contrast stimuli in VEP testing for better detection of visual system damage from toxin exposure.
Area of Science:
- Neuroscience
- Toxicology
- Ophthalmology
Background:
- Solvent-induced chronic encephalopathy can affect visual function.
- Visual evoked potentials (VEPs) are used to assess the visual pathway.
- Contrast sensitivity is a key aspect of visual function that may be impaired by solvent exposure.
Purpose of the Study:
- To investigate the effect of low-contrast stimuli on VEPs in solvent-exposed workers compared to high-contrast stimuli.
- To evaluate the utility of pattern-onset VEPs in detecting damage to specific visual cortical areas.
- To assess disturbances in visual event-related potentials (P300) in solvent-exposed individuals.
Main Methods:
- Thirty male patients with solvent-induced chronic encephalopathy and 41 controls were studied.
- Pattern-reversal checkerboards with low (11%) and high (93%) contrast were used for VEPs.
- Pattern-onset VEPs and P300 (using an oddball paradigm) were also assessed.
Main Results:
- At low contrast, VEP amplitude reduction in patients was 52% compared to 43% in controls, indicating impaired contrast sensitivity.
- Pattern-onset VEPs did not reveal significant effects of solvent exposure.
- Patients exhibited more missed targets, smaller P300 amplitude, and longer P300 latency than controls.
Conclusions:
- The findings support a physiological basis for reduced visual contrast sensitivity in solvent-exposed individuals.
- Neurophysiological examination of the visual system in toxin-exposed persons may benefit from the inclusion of low-contrast VEP stimuli.
- VEP testing with low-contrast stimuli shows promise for detecting subtle visual system impairments due to solvent exposure.