Residual cerebellar ataxia following acute phenytoin intoxication.

A 30-year-old man was given high doses of phenytoin together with 4 antitub erculous drugs for a seizure associated with a probable brain tuberculoma. He developed hepatic toxicity and his serum phenytoin reached the high leve l of 298 mu mol/l (therapeutic range 40-79 mu mol/l). All drugs were stoppe d and the biological parameters returned progressively to normal over the n ext 15 days. However, he remained with a cerebellar axial syndrome and was still severely ataxic 2 months later. Brain CT and MRI showed mild cerebell ar atrophy. This case and the few other published ones, together with some recent experimental data, show that high doses of phenytoin can be toxic to the cerebellar cortical cells. The rarity of similar cases, while millions of epileptics are under phenytoin treatment, would however suggest that in dividual susceptibility may play a role in this toxicity.