[Permanent cerebellar degeneration secondary to diphenylhydantoin (author's transl)].

A patient was treated for a convulsive disorder with "average" doses of diphenylhydantoin, and developed a cerebellar syndrome secondary to drug intoxication, documented by the presence of diphenylhydantoin blood levels above 60 microgram/ml. The individual's low capacity to metabolize the drug appeared to be responsible for the intoxication. The patient has been followed for two years after withdrawal of diphenylhydantoin, and remains incapacitated by a severe unchanged ataxia. The literature on the debated subject of permanent cerebellar degeneration due to diphenylhydantoin is reviewed. The importance of a strict clinical supervision and the measurement of diphenylhydantoin blood levels in any patient treated with this drug is stressed.