Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a treatable autoimmune disease of the CNS with prominent neuropsychiatric features that primarily affects young adults and children.

To present the diagnosis course of a case of anti-NMDAR encephalitis in a patient with previous diagnosis of Schizophrenia.

Analysis of the patient's clinical records and of a PubMed database review, using “anti-NMDAR encephalitis” as keywords.

We report a single case of a 33-year-old man diagnosed with Paranoid Schizophrenia in 2009 that after 1 year of treatment abandoned follow-up. Six years later, the patient presented to the psychiatric emergency department with persistent headaches, abnormal behavior and loss of motor skill. He was admitted to the psychiatric ward with a presumptive diagnosis of “Catatonic Schizophrenia” and began to manifest fluctuating catatonic symptoms (captured in video). Neuroleptics and benzodiazepines were tried without success. There was a clinical deterioration with autonomic dysfunction, breathing instability and seizures. Complementary exams revealed: EEG with slow base activity; brain MRI with right temporal pole and right frontobasal lesions compatible with head trauma; CSF with pleocytosis; and positive anti-NMDAR antibodies. Occult neoplasm was excluded. Treatment with high-dose steroids, intravenous immunoglobulins, followed by cyclophosphamide resulted in relevant clinical improvement.

As early detection of antibodies may allow for earlier treatment of anti-NMDAR encephalitis, which is associated with better outcomes, we believe the present case underscores the importance of clinicians maintaining vigilance for neuropsychiatric symptoms that have not adequately responded to therapy.