Approach and overview of autoimmune encephalitis: A review

Abstract

Autoimmune encephalitis (AE) is an inflammatory disease of the brain parenchyma that is mediated by many specific autoantibodies and is not caused by bacterial or viral causes. A diverse and growing number of autoantibodies have been identified in association with different types of AE. These antibodies can target either intracellular or cell-surface antigens. Advances are being made in understanding the clinical spectrum and treatment of AE. The prevalence and incidence of AE are increasing, although they remain comparable to those of infectious etiologies. The clinical presentation and management of AE are complex, with overlapping features. AE should be considered in the differential diagnosis of treatment-resistant epilepsy. Prompt diagnosis and treatment are critical in preventing seizures from developing into epilepsy. However, the broad differential diagnosis, the inability to detect specific autoantibodies in every patient, and delays in receiving antibody test results impede early diagnosis and treatment. Immunosuppressive agents are primarily used in treatment; first-line options include corticosteroids, intravenous immunoglobulin, and plasmapheresis, while rituximab and cyclophosphamide are used as second-line treatments. This review aims to provide a concise and accessible summary of this topic for readers and researchers.

Keywords: autoantibody; autoimmune encephalitis; epilepsy; immunotherapy; limbic.

Figure 1.

Diagnostic criteria for autoimmune encephalopathy and limbic encephalitis and their interactions.

Figure 2.

MRI sequences in autoimmune encephalitis and its mimics. Standard limbic encephalitis MRI (A) showing bilateral abnormalities in the medial temporal lobe on T2-weighted fluid-attenuated inversion recovery imaging; antineuronal antibodies were not detected in the serum or CSF of this autopsy-confirmed limbic encephalitis patient. The patient had a final diagnosis of glioblastoma (B) and showed signs of limbic encephalitis-like unilateral right hippocampus involvement. An acute disseminated encephalomyelitis (C) typical MRI shows bilateral massive lesions in the white matter. A patient suffering from Susac syndrome (D) has several lesions impacting the corpus callosum. An MRI of a patient with overlapping conditions (anti-NMDA receptor and myelin oligodendrocyte glycoprotein antibodies (E) reveals a demyelinating abnormality that is compatible with a right frontal. An MRI sequence that resembles the alterations observed in individuals with Creutzfeldt-Jakob disease is observed in a patient suffering from AMPA receptor antibody-associated encephalitis (F). AMPA = anti-alpha-amino 3-hydroxy 5-methyl 4-isoxazolepropionic acid, CSF = cerebrospinal fluid, MRI = magnetic resonance imaging, NMDA = N-methyl-D-aspartate.