Autoimmune encephalitis associated with COVID-19: A systematic review

•We present a systematic review of patients infected with COVID19 diagnosed with various forms of autoimmune encephalitis (AE).•The most frequent forms of encephalitis were limbic encephalitis and NMDA receptor antibody mediated encephalitis.•Although rare, clinicians must be aware of AE when considering the neurological differential diagnosis in COVID 19 infected patients. There are increasing reports of COVID-19 related neurological complications which may be due to direct viral invasion, or immune mediated inflammatory diseases such as autoimmune encephalitis and ADEM (acute demyelinating encephalomyelitis). In this study, a systematic review is presented of the reported cases infected by the COVID-19 who were diagnosed with various forms of autoimmune encephalitis (AE). The authors searched three databases including PubMed, Scopus, and Web of science for extracting original articles on coronavirus/ COVID-19 and AE. Eighteen articles were considered in this study, including 15 case reports, and three case series with a total of 81 patients. Among the studies, 19 cases were reported with AE including 7 (37%) cases of limbic encephalitis, 5 (26%) patients with anti-N-methyl-d-aspartate (NMDA) receptor encephalitis, 2 (11%) with AE presenting as new-onset refractory status epilepticus (NORSE), 1 (5%) case of steroid-responsive encephalitis, and 4 (21%) cases with an unknown type of AE. Our systematic review revealed evidence on AE development in patients infected with the COVID-19. Clinicians should be aware of the possible diagnosis of AE when considering other neurological differential diagnosis in SARS-CoV-2 infected patients.