Mondo Description An autoimmune acute encephalitis caused by antibodies against the glutamate NMDA receptor. It usually affects females and in the majority of cases it is associated with the presence of a tumor, most commonly an ovarian teratoma. The presence of a tumor in patients with this form of encephalitis implies that the latter is a paraneoplastic syndrome. It is manifested with psychiatric symptoms and epileptic seizures. It is a potentially lethal disorder; however, it is usually reversible with the prompt removal of the tumor.