Vestibular and oculomotor disturbances caused by industrial solvents.

Hydrocarbon solvents, xylene, styrene, methylchloroform, and trichlorethylene, given intravenously to rabbits produce a positional nystagmus. Due to their additional influence on rotatory nystagmus, one may conclude that their mode of action takes place in the central nervous system. Optokinetic (OKN) responses in rabbits, cats, and humans were also influenced by styrene. OKN responses have not yet been tested for the other solvents. A comparison is made with the effects of alpha-chloralose and the GABA-antagonists bicuculline and picrotoxin which produced similar disturbances. The GABA agonist, baclofen, prevents positional induced styrene nystagmus. It seems likely therefore that the solvents may act by blocking the cerebellar inhibition of vestibulo-oculomotor reflexes. Solvents given simultaneously in some combinations are either additive or synergistic in effect. The implications of these results for occupational medicine are self-evident.