[Residual cerebellar ataxia following acute phenytoin intoxication]. / Ataxie cérébelleuse résiduelle après intoxication aiguë par la diphénylhydantoïne.

A 30-year-old man was given high doses of phenytoin together with 4 antituberculous drugs for a seizure associated with a probable brain tuberculoma. He developed hepatic toxicity and his serum phenytoin reached the high level of 298 mumol/l (therapeutic range 40-79 mumol/l). All drugs were stopped and the biological parameters returned progressively to normal over the next 15 days. However, he remained with a cerebellar axial syndrome and was still severely ataxic 2 months later. Brain CT and MRI showed mild cerebellar 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 individual susceptibility may play a role in this toxicity.