Background: Anti-NMDA receptor encephalitis is a form of autoimmune encephalitis which is characterized by the presence of IgG antibodies against the NR1 subunit of NMDA receptors. While often associated with paraneoplastic origins, the exact triggers of autoantibody production remain unclear in many cases. It predominantly affects children and young adults, with a female preponderance. Cerebrospinal fluid (CSF) analysis is used to confirm the diagnosis. Case Report: A 26 year old female with no comorbidities presented with headache and projectile vomiting followed by altered behaviour. She was taken to a local hospital and was given antipsychotics. After 2 days, she developed recurrent episodes of generalized seizures. On examination, she was disoriented and vitals were unstable. MRI brain was normal. CSF autoimmune panel came as strongly positive for anti-NMDA receptor antibody. She was managed with immunosuppressive medications, multiple antiepileptics and supportive care. Her clinical condition gradually improved and seizures subsided. Whole-body PET–CT performed in search of a tumoral origin was negative. Conclusion: Anti-NMDA receptor encephalitis is a rare and often underdiagnosed condition which requires prompt medical attention and multidisciplinary management. Clinicians should consider anti-NMDA receptor encephalitis in the differential diagnosis for patients presenting with encephalitis, refractory seizures, or acute psychosis, before attributing symptoms to a psychiatric illness. Delayed immunotherapy is associated with poor prognosis.
