Xiaosu Guo,1– 4,* Huimin Shi,1,2,* Yuteng Sun,1 Yuan Xing,1– 3 Xin Guo,1– 3 Zhiyuan Shen,1– 3 Mengyi Zheng,1 Yaxin Zhang,1 Yicun Jia,1 Ye Li,1 Junqiang Bao,1,2 Shujuan Tian1– 3 

1Department of Neurology, The First Hospital of Hebei Medical University, Shijiazhuang, Hebei, People’s Republic of China; 2Department of Neurology, Hebei Hospital, Xuanwu Hospital, Capital Medical University, Shijiazhuang, Hebei, People’s Republic of China; 3Neuromedical Technology Innovation Center of Hebei Province, Shijiazhuang, Hebei, People’s Republic of China; 4Brain Aging and Cognitive Neuroscience Laboratory of Hebei Province, Shijiazhuang, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Shujuan Tian; Junqiang Bao, Department of Neurology, The First hospital of Hebei Medical University, Shijiazhuang, Hebei, 050030, People’s Republic of China, Tel +86-0311-87156309, Email 57203005@hebmu.edu.cn; 57903004@hebmu.edu.cn

Purpose: To summarize the clinical manifestations, laboratory findings, and magnetic resonance imaging (MRI) characteristics of anti-leucine-rich glioma-inactivated 1 (LGI1) antibody encephalitis (anti-LGI1 antibody encephalitis) and explore the electroencephalogram (EEG) features.
Patients and Methods: We retrospectively analyzed the medical history of 16 patients diagnosed with anti-LGI1 antibody encephalitis at the First Hospital of Hebei Medical University from 2021 to 2023. EEGs of patients with anti-LGI1 antibody encephalitis and healthy individuals were analyzed. Based on Video-EEG signal analysis of EEG δ, θ, α, β frequency bands, weighted phase lag index values were calculated to form brain network matrices, studying differences in coherence between brain regions of patients with anti-LGI1 antibody encephalitis and healthy individuals.
Results: Patients with anti-LGI1 antibody encephalitis often presented with subacute onset seizures and cognitive decline. Routine test of cerebrospinal fluid was mostly normal. Serum testing revealed hyponatremia in 62.50% of patients, along with positive serum antinuclear antibodies, decreased vitamin B12, and abnormal cytokines such as interleukin-6. Head MRI revealed abnormal lesions related to the disease in seven cases (43.75%), mainly located in the unilateral or bilateral frontal and temporal lobes of the hippocampus. The EEG mainly showed generalized and focal slow waves, sometimes with focal discharges. Brain network functional connectivity analysis found a significant weakening of functional connections in the frontal-temporal lobe in the δ and β frequency bands. Intravenous pulse corticosteroids and intravenous immunoglobulin are first-line immunotherapies for anti-LGI1 antibody-related encephalitis. The disease recovery and cognitive decline improved in most patients.
Conclusion: Anti-LGI1 antibody encephalitis is characterized by seizures and cognitive dysfunction. Serum may show abnormalities in immune indicators such as cytokines. Head MRI mainly reveals abnormal signals in the frontal-temporal lobes and the hippocampus. EEG brain network connectivity analysis reveals characteristic weakening of functional connections in the frontal-temporal lobe in the δ and β frequency bands.

Keywords: anti-LGI1 antibody encephalitis, epilepsy, electroencephalogram, brain network functional connectivity, immunotherapy