A Sharp Rise in Autoimmune Encephalitis in the COVID-19 Era: A Case Series

Background: Autoimmune encephalitis was very rare prior to the current pandemic. A sharp rise in cases has been observed from March to August of 2022 in Los Angeles. Such an increase, especially with certain types of antibodies, may point toward the possibility of post-infectious autoimmune encephalitis. While review articles on autoimmune encephalitis during this pandemic have been published, a sharp rise in one geographic area within a short period of time has not been documented yet. Aims: To report an alarming increase in autoimmune encephalitis with mostly positive glutamic acid decarboxylase (GAD) and/or voltage-gated potassium channel (VGKC) antibodies over six months during 2022 in Downtown Los Angeles. Material and methods: This is an observational case series from one neurocritical care practice in Downtown Los Angeles. Autoimmune encephalitis antibody panels were sent to patients with altered mental status or neurologic deficits of unclear etiology from March to August of 2022. Results: Of the 29 patients tested, 12 reports came back positive. Ten had positive GAD and/or VGKC antibodies, one had a positive myelin oligodendrocyte glycoprotein antibody, and one had a positive leucine-rich glioma-inactivated 1 protein antibody; a 41% positive rate. Conclusions: This observation has important implications: (1) We may be entering an era of heightened autoimmune encephalitis. (2) These occurrences may be post-infectious in nature at this point of the pandemic. (3) Mostly GAD and VGKC antibodies have been identified (10 of them), which may point toward a new direction of research from a molecular mimicry standpoint. (4) To benefit patients, clinicians need to be aware of such disease manifestations and increase testing; resources must be increased to improve test availability and shorten turnaround time; and treatment, which is expansive, must be made widely available for these potentially reversible diseases.