Electroclinical biomarkers of autoimmune encephalitis

•Autoimmune encephalitis is a rare illness that commonly presents with seizures.•Electroencephalography can provide diagnostic and prognostic information in AIE.•Different AIE subtypes show unique characteristics on EEG to aid early diagnosis.•Abnormal EEG background was associated with outcome at discharge and 12 months. To evaluate the utility of electroencephalography (EEG) changes as diagnostic and prognostic biomarkers in acute autoimmune encephalitis (AIE). One hundred and thirty-one patients with AIE were recruited retrospectively across 7 hospitals. Clinical data were collected during admission and at 12 months. EEGs were reviewed using a standard reporting proforma. Associations between EEG biomarkers, AIE subtypes, and clinical outcomes were assessed using logistic regression modeling. Presence of superimposed fast activity (OR 34.33; 95% CI 3.90, 4527.27; p