Clinical, Electroencephalogram and Imaging Characteristics of Patients With Anti‐LGI1 Antibody Encephalitis: A Multicenter Cohort Study

ABSTRACT Objectives To summarize the clinical, electroencephalogram (EEG), and imaging characteristics of patients with anti‐leucine‐rich glioma‐inactivated 1 autoimmune encephalitis (LGI1‐AE) and provide a reference for clinical diagnosis and treatment. Methods We retrospectively analyzed 88 patients diagnosed with LGI1‐AE between January 2018 and April 2024 in the Department of Neurology, Huashan Hospital, Fudan University, and the First Hospital of Jilin University. Results This retrospective study analyzed 88 patients diagnosed with LGI1‐AE. The initial clinical presentation predominantly featured rapidly progressive cognitive impairment (RPCI) (51.1%) and seizures (50%). Brain magnetic resonance imaging and 18 F‐fluorodeoxyglucose positron emission tomography (18F‐FDG PET) indicated predominant lesion localization in the unilateral or bilateral temporal lobe and/or basal ganglia. Abnormal EEG was observed in 66 cases (79.5%). LGI1‐AE cases had increased power in the low‐frequency bands (δ and θ) compared to normal controls. Low‐frequency band (δ and θ) power in T3 and Fz channels was positively correlated with LGI1 antibody titers in cerebrospinal fluid (CSF). Spearman correlation analysis showed that baseline modified Rankin Scale (mRS) scores were correlated with serum antibody titers and CSF antibody titers. Conclusions Baseline mRS scores and low‐frequency power in the frontotemporal region showed a positive correlation with anti‐LGI1 antibody titers, suggesting that antibody levels may reflect disease severity in LGI1 autoimmune encephalitis. Further studies are warranted to validate these associations in prospective multicenter cohorts.