Movement disorder as a manifestation of diphenylhydantoin intoxication

Abstract

A choreoathetoid movement disorder may be a rare manifestation of diphenylhydantoin intoxication. In two patients with high serum DPH levels (40 and 65 mcg per milliliter), constant irregular flapping and chewing movements were present. These abnormal movements disappeared with falling serum diphenylhydantoin levels. Nystagmus was absent in both patients initially although it appeared transiently in one. Both patients have been maintained since on 300 mg of diphenylhydantoin daily without recurrence of symptoms, suggesting that excessive medication was responsible for the intoxication. A review of the literature revealed three similar cases, in one of which the drug intoxication resulted from a defect in drug catabolism.