[NMDA-GluR Subunit Antibody-Positive Encephalitis: A Clinical Analysis of Five Cases]

Five consecutive cases of anti-NMDA-receptor encephalitis that we encountered were marked by a rapidly fluctuating level of consciousness associated with psychotic and delirious mental states. Opisthotonus, catatonia, and rhythmic and non-rhythmic involuntary movements of the mouth and jaw were also characteristic features of these particular cases. Serious and potentially fatal problems included epilepsia partialis continua, partial and generalized seizures, and respiratory depression, resembling the symptoms of encephalitis lethargica. An epidemic of encephalitis lethargica, also known of Economo encephalitis, occurred around 1917. Magnetic resonance imaging revealed edema of the neocortex in two cases and electroencephalography showed polymorphic and monomorphic delta slowing in the acute stage, although electroencephalographic seizure activity were not apparent. Routine cerebrospinal fluid analyses revealed lymphocyte-dominant pleocytosis in three cases, but antibodies against the NMDA-GluR subunit, GluN2B N-terminal, were at a high level in the fluid. All patients recovered without apparent sequelae. Two patients found to have ovarian teratoma underwent surgery for tumor removal. Treatments included pulse intravenous methylprednisolone, high-dose immunoglobulin, and plasma exchange together with seizure control and respiratory support. However, rituximab and or cyclophosphamide pulse therapy should also be considered for intractable cases, as indicated by recent reports. (Received February 16, 2016; Accepted May 2, 2016; Published September 1, 2016).