Case Report: Case Report: Autoimmune Limbic Encephalitis Associated with LGI1 Antibodies

Abstract

Introduction: Autoimmune encephalitis (AD) is a group of diseases caused by the presence of autoantibodies on the neuronal surface or intracellular antigens. The most commonly involved neuronal surface antigens include the voltage-gated potassium channel protein complex (VGKC), which includes leucine-rich glioma inactivated protein 1 (LGI1) and contactin-like protein 2 (CASPR2), both of which are linked to encephalitis, neuromyotonia, Morvan syndrome, and painful neuropathy. Anti-LGI1 antibody-associated encephalitis is a subtype of AD, characterized by an inflammatory pattern that predominantly affects the limbic system. Anti-LGI1 antibodies can prevent synaptic transmissions involved in learning, behavior, and memory processes due to neuronal hyperexcitability and dysfunction of synaptic plasticity. Case report: A 33-year-old male patient presented with an insidious, oppressive holocranial headache associated with episodes of piloerection, parosmia, and photopsias lasting minutes. Subsequently, anomie during family conversations and an episode of short-term temporal-spatial disorientation and dystonic seizures with a faciobrachial predominance < duration of 1 minute without loss of consciousness were added to the clinical picture. Conclusions: LGI1 antibody-associated encephalitis represents a significant diagnostic challenge due to its heterogeneous clinical presentation and its onset at younger ages than usual. The case presented shows the importance of considering this entity in young patients with cognitive impairment, faciobrachial dystonic seizures and characteristic magnetic resonance findings, even in the face of a normal EEG.