Abstracts

Rationale: Autoimmune synaptic encephalitis (ASE), a rare condition comprising encephalitides associated with autoantibodies against structures of the neuronal synapse, usually accompanies seizure disorder. Leucine-rich glioma inactivated 1 (LGI1), a glycoprotein secreted from presynaptic terminal that regulates presynaptic kv1 channels and post synaptic AMPA receptors, is recently identified as target proteins in ASE, which was formerly attributed to voltage-gated potassium channels. Studies deals with it are small in number. To strengthen our understandings, we presented 11 cases with LGI1 antibodies herein.Methods: Clinical analysis was conducted on patients with suspected ASE. Autoantibodies to NMDAR, LGI1, CASPR2, AMPA1, AMPA2, GABAB-R were checked by indirect immunofluorescence test.Results: Eleven patients with Anti-LGI1 encephalitis were identified. Male to female ratio was 6 to 5 and median age of 61 (range 41-78). All patients presented with seizure, including 6 with brief faciobrachial dystonic seizure (FBDS). 9 patients showed cognitive impairment, mainly memory dysfunction and/or behavioral change. 2 patients had prominent autonomic symptoms, such as orthostatic dizziness, urinary incontinence, and constipation. Ancillary tests such as electroencephalogram, brain magnetic resonance imaging and fluorodeoxyglucose positron emission tomography (FDG-PET) identified medial temporal and/or basal ganglia abnormality in 8 patients. All patients showed symptomatic improvement after immunotherapy.Conclusions: Anti-LGI1 encephalitis is characterized by seizure, cognitive dysfunction, FBDS, basal ganglia hypermetabolism on FDG-PET and hyponatremia. Anti-epileptic therapy is not sufficient to control the symptoms, and early diagnosis and immunotherapy are of importance.