Immunological abnormalities associated with chronic encephalitis, epilepsy, and progressive hemiplegia in a three-year, nine-month old girl are reported from the University of Utah School of Medicine and the Primary Children's Medical Center, Salt Lake City, Utah. The child developed simple partial seizures refractory to medications and associated with a contralateral hemicerebral atrophy. Immunologic abnormalities were indicated by elevated antinuclear antibody, CSF oligoclonal bands and elevated immunoglobulin G (IgG). A right subtotal hemispherectomy resulted in control of the seizures. Pathological study showed widespread cerebral vasculitis and severe cortical atrophy with marked neuronal loss. 
COMMENT: Immunofluorescence microscopy revealed granular accumulation of IgG, IgM, IgA within the cerebral vessels of this patient suggesting an immune complex disease as the basis for Rasmussen's syndrome.