Vestibulo-oculomotor disturbances caused by industrial solvents.

Animal experiments show that intoxication with hydrocarbon solvents influences the vestibulo-oculomotor reflex arc and indicate that the solvents block the inhibition of the vestibulo-oculomotor reflex presumably exerted by the cerebellum. The blood concentrations necessary to elicit oculomotor disturbances in animals were smaller than those that disturbed the vestibular function. Accordingly, in human experiments styrene and toluene exposure did not elicit any positional nystagmus but caused an increased saccade speed and a diminished visual suppression of vestibular nystagmus. Some cerebellar clinical pathologic process in patients who suffer from a psycho-organic syndrome caused by solvents leads us to believe that the cerebellum might be the most vulnerable part of the brain. Some patients had a positional nystagmus, but the most prominent pathologic signs were elicited by the visual suppression test. Our findings compare well with the increased saccade speed and diminished visual suppression in patients with cerebellar tumors and infarctions.