[Cerebellar atrophy and persistent cerebellar ataxia after acute intoxication of phenytoin].

Chronic intoxication of phenytoin (PHT) is a well known cause of cerebellar atrophy or irreversible cerebellar ataxia. Little attention, on the other hand, is paid for acute PHT intoxication because its clinical signs are believed to be reversible. We here report a patient with acute PHT intoxication, which resulted in irreversible cerebellar ataxia with radiologically definite cerebellar atrophy. A 39-year-old man admitted to our hospital because of cerebellar ataxia and confusional state. He had been treated with PHT for convulsive seizures after receiving craniotomy for left parietal brain abscess 9 years before. The concentration of his serum PHT had been 4 to 7 micrograms/ml because he had frequently omitted taking drug, and the dose of PHT had been increased to 600 mg/day one year before. He had admitted to another hospital 2 months before for left Bell's palsy and had been obliged to take drug regularly. Cerebellar signs and confusion had gradually developed for 7 weeks. On admission to our hospital, he was awake but in severe confusional state with slurred speech and nystagmus. His serum PHT was 86 micrograms/ml, which returned to therapeutic range 2 weeks after the discontinuation of PHT. His consciousness normalized and nystagmus disappeared. However, slurred speech continued and neurological examination revealed postural tremor and severe limb ataxia. During the subsequent 10 months, his cerebellar signs showed minimal improvement. Computed tomographies of his brain on 3rd and 5th month after the onset of his cerebellar dysfunction showed the definite cerebellar atrophy which had not been noted on the CTs 7 months before and 7 weeks after the onset.(ABSTRACT TRUNCATED AT 250 WORDS)