Subacute necrotizing polioencephalopathy.

A previously healthy 20-year-old woman died of a progressive cerebral disease that involved the brain stem and the cerebral hemispheres successively. The illness ran its course in 80 days. Postmortem examination showed a multifocal necrotizing encephalopathy that chiefly affected gray matter structures and that was mainly located in the brain stem and cerebral cortex. The cause and pathogenesis remain unknown.