Rationale: 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) patients and explore their electroencephalogram (EEG) features.
Methods: A retrospective analysis was conducted on 16 patients diagnosed with anti-LGI1 antibody encephalitis from May 2020 to May 2023 at the First Hospital of Hebei Medical University. Clinical manifestations, laboratory tests, head MRI findings were reviewed, and patients were assessed for prognosis through telephone follow-up. The clinical characteristics of anti-LGI1 antibody encephalitis patients were summarized. Video-EEGs of anti-LGI1 antibody encephalitis patients and age- and gender-matched healthy individuals were analyzed. Based on Video-EEG signal analysis of EEG δ, θ, α, β frequency bands, weighted phase lag index (WPLI) values were calculated to form brain network matrices, studying differences in coherence between brain regions of anti-LGI1 antibody encephalitis patients and healthy individuals.
Results: Anti-LGI1 antibody encephalitis patients often presented with subacute onset, seizures, cognitive decline, behavioral abnormalities, dizziness, and frequently accompanied by sleep disorders. Cerebrospinal fluid pressure, routine and biochemical tests were mostly normal. Serum testing revealed hyponatremia in 62.50% of patients, along with positive serum antinuclear antibodies, decreased vitamin B12 (VitB12), abnormal cytokines such as interleukin-6 (IL-6). Head MRI revealed abnormal lesions related to the current disease in 7 cases (43.75%), mainly located in the unilateral or bilateral frontal and temporal lobes, hippocampus, showing iso-/hyperintensity on T1, hyperintensity on T2, high Flair signal. EEG of anti-LGI1 antibody encephalitis patients mainly showed generalized and focal slow waves, sometimes with focal discharges. Brain network functional connectivity analysis found significant weakening of functional connections in the frontal-temporal lobe in the δ and β frequency bands compared to healthy individuals(Figure1 and 2). Intravenous pulse corticosteroids, intravenous immunoglobulin (IVIg) are first-line immunotherapy for anti-LGI1 antibody-related encephalitis. With disease recovery, cognitive decline in most patients improved.
Conclusions: Typical symptoms of anti-LGI1 antibody encephalitis patients include seizures and cognitive dysfunction. Serum may show abnormalities in immune indicators such as cytokines. Head MRI mainly reveals abnormal signals in frontal-temporal lobes and hippocampus. Brain network connectivity analysis of Video-EEGs reveals characteristic weakening of functional connections in the frontal-temporal lobe in the δ and β frequency bands of anti-LGI1 antibody encephalitis patients.
Funding: This work was supported by the National Key Research and Development Program of China(2022YFC3600500，2022YFC3600503), Scientific and Technological Innovation 2030-Major Project Subject of Brain Science and Brain-inspired Research (2021ZD0201807), Hebei Province Government-funded Excellent Talents Project in Clinical Medicine (2022-180-5).