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Título

OPTICAL NEUROTOXICITY BY TOLUENE

RESUMO

Case presentation: A 32-year-old male, illicit drug user, was evaluated for bilateral visual loss after inhaling large amounts of thinner and accidently ingesting the product, in addition to touch his eyes with the product's dirty hands. A day after the event, he developed bilateral intense retrocular pain that worsened with eye movement, associated with photophobia and diffuse myalgia. He evolved with significant loss of visual acuity, remaining with only light perception. He was assessed by an ophthalmologist who did not find ocular or retinal changes. Eight days later the accident, he was then referred to this neurology service with non-reactive mydriatic pupils, bilateral amaurosis, with only light perception. Cranial CT was normal and CSF showed high protein levels. He was subsequently diagnosed with a bilateral optic nerve damage due to optic neurotoxicity caused by toluene present in thinner. Discussion: Thinner is a solvent for paints and varnishes, used in automobiles paint and body shops. Its main compound is toluene, a fat-soluble which is rapidly absorbed by the lipid-rich CNS, its primary target. Its distribution in the body and excretion are quite rapid. All the absorbed compound is almost completely eliminated from the body 18 to 20 hours after exposure. Acute manifestations of toluene toxicity include euphoria, headache, weakness, vision disturbances, tremors, confusion, ataxia, paralysis, epileptic crisis, narcosis, and death. In addition, toluene optic neuropathy may occur, which leads to a slow and progressive decline in visual acuity. The initial appearance of the optic disc is usually normal, but there is gradual optic atrophy. Final comments: Hippuric acid is a biological indicator of exposure to toluene, excreted in the urine. However, some authors claim that there is no diagnostic value in its dosage, as it is a normal constituent of urine. Thus, after discussing the condition with the toxicology team of a reference hospital, it was decided not to measure this marker, since the main suspicion would remain, even with a negative test. A fat-suppressed MRI of the skull and orbits were performed, showing discreet tortuosity of optic nerves and peri sheath fluid at the insertion of the eyeball, suggestive of neuritis. He underwent pulse therapy for 5 days with methylprednisolone, without clinical improvement.

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