OBSOLETE: Limbic encephalitis

Limbic encephalitis is a neurological condition characterized by inflammation of the limbic system, which includes structures of the brain involved in memory, emotion, and behavior — particularly the hippocampus, amygdala, and related temporal lobe regions. Patients typically present with subacute onset of short-term memory loss, confusion, seizures, psychiatric symptoms (such as anxiety, depression, personality changes, or hallucinations), and sleep disturbances. The condition can be associated with autoimmune antibodies directed against neuronal surface or intracellular antigens, and in some cases it occurs as a paraneoplastic syndrome related to an underlying malignancy (most commonly small cell lung cancer, testicular germ cell tumors, breast cancer, or thymoma). It is important to note that this Orphanet entry (ORPHA:163892) is classified as OBSOLETE, meaning the concept has been retired or reorganized within the Orphanet classification system. Limbic encephalitis is now more precisely categorized under broader or more specific entities such as autoimmune encephalitis or paraneoplastic neurological syndromes, reflecting advances in the understanding of antibody-mediated and paraneoplastic central nervous system disorders. Specific subtypes are now recognized based on the associated antibody (e.g., anti-NMDA receptor encephalitis, anti-LGI1 encephalitis, anti-CASPR2 encephalitis, anti-AMPA receptor encephalitis, among others). Treatment depends on the underlying cause. When an associated tumor is identified, treatment of the malignancy is a critical first step. Immunotherapy — including corticosteroids, intravenous immunoglobulin (IVIG), plasma exchange, rituximab, or cyclophosphamide — is commonly used to reduce the autoimmune-mediated inflammation. Early diagnosis and treatment are associated with better neurological outcomes, though some patients may experience residual cognitive deficits, particularly memory impairment.

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