Post Herpes Simplex Virus (HSV) NMDA Encephalitis

 Anti-N-methyl D-aspartate (NMDA) receptor (anti-NMDAR) encephalitis is caused by immunoreactivity against the NR1 subunit of the NMDA receptor. The anti NMDAR encephalitis has strong association in patients with Herpes Simplex Virus (HSV) encephalitis. Post viral infection the cause of encephalitis was of the autoimmune type (Anti NMDAR Encephalitis). We present that case of a twenty-one-year-old female with acute confusion, irrelevant talk, abnormal behavior and one episode of generalized tonic clonic seizure. She was hospitalized 25 days back with febrile encephalopathy with a positive CSF-PCR for HSV Type 2. Patient was started on steroids and autoimmune encephalitis antibodies profile was sent. This came positive for NMDA receptor and negative for CASPR-2, Type AMPA1/2, LGI-1, DPPX, and GABAB receptor antibodies. The patient was administered IV rituximab every four weeks after a poor outcome with steroid therapy. The patient was doing well on four weeks follow up. Herpes Simplex Virus (HSV) infection preceded the diagnosis of NMDA Encephalitis. The diagnosis of autoimmune encephalitis should be considered a top differential in relapsing patients as it has a very wide range of presentation. Prompt diagnosis and early treatment are the need of the hour as the ramifications of a mis or missed diagnosis could be detrimental