[Anti-LGI1 antibody encephalitis: A monocentric retrospective series of seven patients]

Anti-leucine-rich glioma-inactivated 1 (LGI1) autoimmune encephalitis is a rare neurological disorder caused by autoantibodies targeting the LGI1 protein, leading to synaptic dysfunction predominantly affecting the temporal lobes and hippocampi. It is mainly characterized by cognitive impairment, focal seizures, and faciobrachial dystonic seizures. The aim of this study was to describe the clinical, paraclinical, therapeutic, and outcome characteristics of patients managed at our center. We conducted a retrospective study including seven patients diagnosed between 2016 and 2024. The median age at diagnosis was 71 years. Cognitive impairment, predominantly memory deficits, was the most common presenting feature. Brain magnetic resonance imaging (MRI) showed abnormalities in six of seven patients (85.7%). The diagnosis was confirmed by the detection of anti-LGI1 antibodies in serum and/or cerebrospinal fluid (CSF). First-line immunotherapy combining corticosteroids and intravenous immunoglobulins resulted in early clinical improvement in five patients (71.4%). However, several patients required second-line immunosuppressive therapy because of an insufficient response or disease relapse. Persistent neurocognitive deficits were observed in some patients during follow-up. This case series highlights the importance of early diagnosis and prompt initiation of immunotherapy to improve functional outcomes and reduce long-term cognitive impairment. Long-term follow-up is essential to detect relapses and optimize therapeutic management.