Detection of anti-NMDA receptor antibodies following BBIBP-CorV COVID-19 vaccination in a rituximab-treated person with multiple sclerosis presenting with manifestations of an acute relapse

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a relatively unknown autoimmune entity. Scant reports of post-infection/vaccination anti-NMDAR encephalitis exist. We, hereby, reviewed the relevant cases and added to the literature a possible case of anti-NMDAR encephalitis following COVID-19 vaccination with BBIBP-CorV (Sinopharm). A 50-year-old Persian woman with previously known rituximab-treated MS presented complaining of worsening neurological symptoms all gradually starting and worsening after receiving the second dose of BBVIP-CorV 2 weeks before. Notable findings in her physical examination included ataxic gait and Babinski sign. Considering an acute MS relapse, corticosteroid pulse therapy was initiated, and she was referred for MRI, which revealed multiple new plaques. Her serum sample interestingly tested positive for anti-NMDAR antibodies. CSF analysis was unfortunately not performed. She responded well to the corticosteroid pulse therapy and showed substantial resolution of the symptoms. Considering its relatively low cost of workup and the benefits of correct early diagnosis, clinicians are advised to consider autoimmune encephalitis encountering patients with progressive neurological symptoms after the administration of vaccines, including the ones for COVID-19 which are currently being used extensively.