Six previously healthy children who developed an acute encephalopathy several days after a prodromal illness are reported from the Hopital Bicetre, and Hopital Necker-Enfants Malades, Paris, France. Prodromal illnesses consisted of upper respiratory infection with fever, and headache and vomiting. Coma was the initial symptom in 4 patients. Abnormal movements included gesticulation, chewing, swallowing, orofacial dyskinesia, limb dystonia, and choreoathetosis. Rigidity was constant in 5 patients and intermittent in one. Seizures occurred in 2 patients. Recovery extended for several weeks and was characterized by a rapid return of motor function and persistent behavioral and cognitive disturbances. Four patients recovered fully, and two had mild sequelae. 
COMMENT. These cases with a favorable outcome were thought to represent a different syndrome from that described by Lyon, Dodge, and Adams, whose 16 patients died from an acute encephalopathy of obscure origin. Attempts at viral isolation and antibody detection were negative.