Title : Delayed recognition of anti-NMDAR encephalitis mimicking primary psychiatric illness: A case report
Abstract:
Background: Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a potentially reversible autoimmune encephalitic disorder characterized by a distinctive neuropsychiatric phenotype and a strong association with ovarian teratomas in young women. Its early manifestations may closely resemble primary psychiatric illness, create a critical diagnostic blind spot and delay disease-specific intervention.
Case Presentation: A 33-year-old woman without a previous psychiatric history presented with a rapidly progressive neuropsychiatric syndrome characterized by sleep disturbance, behavioral disorganization, aggression, paranoia, hallucinations, inappropriate behavior, and progressive reduction in responsiveness. She was initially diagnosed with acute and transient psychotic disorder and treated with antipsychotic and sedative therapy. Her clinical trajectory subsequently became atypical, with fluctuating consciousness, disorientation, abnormal involuntary movements, urinary retention, and features of encephalopathy, prompting neurological reassessment. Cerebrospinal fluid evaluation demonstrated anti-NMDAR antibodies, establishing the diagnosis of autoimmune encephalitis. Given the recognized association with ovarian neoplasia, targeted abdominal and pelvic imaging was undertaken and revealed a left ovarian teratoma.
Management and Outcome: A multidisciplinary team comprising psychiatry, neurology, radiology, gynecology, and critical care coordinated her management. First-line immunotherapy with intravenous methylprednisolone followed by intravenous immunoglobulin was administered, alongside supportive and symptomatic care. Laparoscopic left oophorectomy was subsequently performed during the same admission to eliminate the presumed antigenic trigger. The patient demonstrated progressive neurological, cognitive, and behavioral recovery, with resolution of agitation and abnormal movements and no documented relapse during follow-up.
Conclusion: This case underscores the diagnostic vulnerability of young women presenting with acute psychiatric manifestations and highlights the importance of recognizing rapidly evolving symptoms, fluctuating consciousness, dyskinesias, and autonomic dysfunction as red flags for autoimmune encephalitis. Early neurological reassessment, cerebrospinal fluid antibody testing, systematic tumor screening, prompt immunotherapy, definitive management of an associated ovarian teratoma, and coordinated multidisciplinary care are pivotal to minimizing diagnostic delay and optimizing neurological recovery.
