Movement disorder as a manifestation of diphenylhydantoin toxicity

A patient with a long-standing seizure disorder developed a choreic movement disorder, clinically indistinguishable from Sydenham's chorea when his blood diphenylhydantoin level was clearly in the toxic range. His movement disorder cleared promptly as the diphenylhydantoin level dropped, all other medications being continued. Thus, DPH intoxication should be considered as a rare cause of chorea in childhood.