Anti-NMDA-receptor encephalitis, a frequent cause of encephalitis in the intensive care unit

Abstract

Paraneoplastic autoimmune encephalitis results in rapidly evolving symptoms encompassing behavior changes, mood disorders, seizures, memory deficits, and possible decline of consciousness associated to an inflammation of the cerebrospinal fluid (CSF) and abnormalities on cerebral imaging. Among these encephalitis, the recently described anti-NMDA-receptor encephalitis seems more common. According to an epidemiological prospective study, this encephalitis represents up to 4% of all causes of encephalitis; the 5th cause of encephalitis after Herpes simplex virus, Varicelle zona virus (VZV), Mycobacterium tuberculosis infections, and acute demyelinating encephalomyelitis (ADEM), and thus the second cause of autoimmune encephalitis after ADEM. Anti-NMDA-receptor encephalitis predominantly affects young people, especially women. The clinical presentation is characteristic and includes rapidly evolving behavioral changes, prominent psychiatric symptoms with delusion and psychosis, seizures, abnormal movements, autonomic instability, and central hypoventilation. Admission to the intensive care unit is common for hypoventilation or decreased consciousness. Presentation is associated with the presence of an ovarian teratoma in two-third of the cases. Diagnosis is assessed based on the identification of specific antibodies against NMDA-receptor in the CSF, as well as indirect data obtained using electroencephalography and cerebral imaging. Treatment relies on immunotherapy, corticosteroids associated to intravenous immunoglobulins or plasma exchange, and resection of the germinal tumor. If diagnosed and treated early, anti-NMDA-receptor encephalitis has a mortality rate of 4% and a favorable outcome in about two-third of the patients.