Anti-
N-methyl-d-aspartate receptor (NMDAR)
encephalitis is a disease occurring when
antibodies produced by the body's own immune system attack
NMDA-type
glutamate receptors in the brain. Most
anti-NMDAR encephalitis cases are associated with
paraneoplastic syndrome. We analyze the case of a 15-year-old girl who was hospitalized in a child psychiatry clinic in Riga, Latvia, with de novo acute polymorphic
psychotic disorder gradually progressing to a catatonic state. The patient received
antipsychotic and electroconvulsive therapy with no beneficial effect. The council of doctors discussed differential diagnoses of
schizophrenia-induced
catatonia and the
autoimmune limbic encephalitis-induced catatonic condition. When the diagnosis of anti-NMDAR
autoimmune encephalitis was finally confirmed by repeated immunological assays (specific
immunoglobulin [Ig] G and
IgM in her blood serum and cerebrospinal fluid), and a paraneoplastic process was ruled out, she was started on immunomodulating
therapy (
methylprednisolone, Ig,
plasmapheresis,
rituximab), which changed the course of
her disease. On immunomodulating treatment, her physical and mental health have gradually improved to almost complete reconvalescence. Psychiatrists should consider
anti-NMDAR encephalitis as a differential diagnosis in first-episode
psychosis patients presenting with disorientation, disturbed consciousness, pronounced cognitive deficits,
movement disorder,
dysautonomia, or rapid deterioration, and test for specific
IgG NR1
autoantibodies, even if there are no specific findings on routine neuroimaging, electroencephalography (EEG), or cerebrospinal fluid tests.