Anti-NMDA encephalitis normally appears as a characteristic syndrome with typical symptoms that undergoes with multiphase evolution. However, it sometimes develops atypical symptoms so we must perform a careful differential diagnosis.

To conduct a current review of detection and management of anti-NMDAr encephalitis, and psychiatric manifestations.

Systematic review of the literature in English (PubMed), with the following keywords: “Autoimmune encephalitis”, “psychosis”, and “NMDA receptor”.

We present the case of a 15-year-old boy referred to evaluation for a first psychotic episode. He had no past history of psychiatric illness or substance abuse. The only relevant antecedent is multiple sclerosis in a first degree relative. For the last months, he presented high levels of anxiety symptoms apparently related to college stressful events and fluctuating hypoesthesia of left cranial side. Days later, it appeared autolimited gastrointestinal symptoms, headache and fever. During the next days it appeared psychomotor retardation, choreic movements, suicide ideation and mood-congruent paranoid and nihilistic ideation, auditory and visual hallucinations, perplexity and catatonic symptoms so he was hospitalized. We observed cognitive functions impairment, unsteady gait, dysartria, dysphasia, clonus and left babinsky sign. EEG showed slow waves on right frontal area. CFS showed protein elevation and immunologic study revealed positive anti-NMDA antibodies. Treatment with methylprednisolone and gammaglobuline was started with partial response, needing addition of rituximab.

In this case, we highlight the importance of early detection and a detailed differential diagnosis, to determine whether the etiology of psychiatric symptoms in order to achieve an accurate and early treatment.