Postvaccinal encephalomyelitis without cutaneous vaccination reaction.

A 5-year-old girl developed a progressive febrile neurological illness consisting of right focal seizures, right hemiparesis, and stupor evolving over a period of six weeks. During the month preceding the onset of her illness she had received two apparently unsuccessful smallpox vaccinations without a skin lesion. Elevation of cerebrospinal fluid gamma globulin and findings on brain biopsy were consistent with postinfectious encephalitis, and a simultaneous increase in serum vaccinia antibody titer suggested that the illness was postvaccinial encephalitis. Clinically, the child developed a severe extrapyramidal movement disorder during the acute phase followed by nine months of stuporous unresponsiveness, yet subsequently made a substantial recovery.