Possible Autoimmune Encephalitis Associated with the Severe Acute Respiratory Syndrome Coronavirus 2 Omicron Variant Successfully Treated with Steroids

We encountered a 55-year-old woman with possible autoimmune encephalitis associated with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant. She was not vaccinated against coronavirus disease 2019 (COVID-19). Consciousness disturbance, myoclonic-like movements and gait disturbance occurred 10 days after the COVID-19 symptom onset. Her neurological symptoms improved two days after methylprednisolone pulse therapy. Cerebrospinal fluid (CSF) was negative for SARS-CoV-2 reverse transcription-polymerase chain reaction, the CSF-to-serum albumin quotient was mildly elevated, and interleukin 6 and 8 levels were normal in serum but mildly elevated in CSF. Omicron variant infection may increase blood-brain barrier permeability and intrathecal inflammation, causing autoimmune encephalitis.