Investigators at Brown University, Providence, RI and other centers in the US and Canada report a 14-month old child with multiple episodes of febrile status epilepticus, followed by chorea and developmental regression, caused by human herpes virus-6 encephalitis. Chorea and seizures resolved following treatment with levetiracetam, IV immunoglobulin, and foscarnet, but developmental regression with loss of language skills persisted at 6 months follow-up. This is considered a novel manifestation of HHV-6 encephalitis. 
COMMENT. HHV-6B is the cause of one third of all febrile convulsions in children under age 2 years in the United States , and a cause of mesial temporal lobe epilepsy after febrile status epilepticus . Other disorders attributed to HHV-6 infection include meningoencephalitis, encephalopathy, demyelinating diseases, ataxia, opsoclonus-myoclonus, and cranial neuropathies. In addition to symptoms of involvement of the cerebral cortex, brain stem, cerebellum, spinal cord, hippocampus, and mesial temporal lobe, HHV-6 infection may also present with symptoms of basal ganglia virus involvement, either direct or autoimmune.