Smoldering encephalitis in children.

Five children presented with focal seizures and neurological deficits that progressed over a span of months to years. Three had temporal lobectomy to control seizures, one underwent temporal lobe biopsy, and the fifth, who suffered from immunodeficiency, had an occipital lobectomy to remove a mass. Two of the children expired. Neuropathological findings in all five children were consistent with a persistent active "viral" encephalitis. No infectious agent was identified. None of the children had the usual systemic signs of encephalitis and all lacked an inflammatory response in their cerebrospinal fluid. We conjecture that this condition may be more frequent than realized. Besides causing intractable focal seizures and hemiparesis, it may account for other poorly understood syndromes of childhood with deteriorating behavior.