Autoimmune Epilepsy: Insights into Pathophysiology, Diagnostic Strategies and Treatment
Abstract Autoimmune epilepsy, once regarded as a rare and poorly understood subset of seizure disorders, has now emerged as a clinically significant and potentially reversible cause of epilepsy. Advances in neuroimmunology have substantially broadened the spectrum of neural autoantibodies implicated in epileptogenesis—particularly those directed against neuronal cell surface and synaptic proteins, such as the N-methyl-D-aspartate receptor (NMDAR), leucine-rich glioma-inactivated protein 1 (LGI1), contactin-associated protein-like 2 (CASPR2), and glutamic acid decarboxylase 65 (GAD65). Distinct autoantibody profiles are now recognized to correlate with characteristic clinical syndromes, facilitating earlier and more targeted diagnosis. For instance, faciobrachial dystonic seizures are highly suggestive of LGI1 antibody-mediated encephalitis, while neuropsychiatric manifestations and movement disorders are typical of NMDAR antibody encephalitis, and chronic temporal lobe epilepsy frequently accompanies GAD65 autoimmunity. Early identification of these immune-mediated forms is critical, as antibody-mediated epilepsies involving cell surface antigens often respond favorably to immunotherapy, leading to substantial recovery. In contrast, epilepsies associated with intracellular antigen targets or cytotoxic T-cell–driven mechanisms, such as Rasmussen encephalitis, typically show poor therapeutic response due to irreversible neuronal injury. Some autoimmune encephalitides also occur as paraneoplastic syndromes, underscoring the importance of comprehensive oncological evaluation in affected patients. Moreover, immune dysregulation has been implicated in catastrophic epileptic conditions such as new-onset refractory status epilepticus and febrile infection-related epilepsy syndrome, further broadening the clinical spectrum of autoimmune-mediated seizures. Although seizures may arise from diverse etiologies, immune mechanisms have gained increasing recognition as an important and potentially modifiable contributor to epileptogenesis. This recognition has been formally endorsed by the International League Against Epilepsy, which classifies autoimmune epilepsy as a distinct diagnostic entity. Nevertheless, true autoimmune epilepsy, in which seizure susceptibility persists after resolution of encephalitic activity, remains relatively uncommon. In most cases, seizures associated with autoimmune encephalitis are acute and reversible with timely immunotherapy. Thus, precise terminology—differentiating acute symptomatic seizures from chronic autoimmune-associated epilepsy—is essential for appropriate management, prognostication, and research standardization.