Involuntary movements caused by phenytoin intoxication in epileptic patients

Abstract

The case histories of 4 patients who developed choreoathetoid movements during intoxication with phenytoin are presented. Drug intoxication was confirmed in each case by measuring the serum phenytoin concentration. Drug interactions were, in part, responsible for the occurrence of intoxication in 3 of them. Phenytoin intoxication is not always easy to recognize, particularly when nystagmus is minimal or absent, as in these 4 patients. The estimation of the serum phenytoin concentration is invaluable in this situation.