OBSOLETE: Paraneoplastic limbic encephalitis

Paraneoplastic limbic encephalitis (PLE) is a rare neurological condition classified under paraneoplastic neurological syndromes, in which the body's immune response to an underlying cancer (most commonly small cell lung cancer, testicular germ cell tumors, breast cancer, or thymoma) mistakenly attacks the limbic system of the brain. The limbic system, which includes the hippocampus and amygdala, is critical for memory, emotions, and behavior. This Orphanet entry (163895) is marked as OBSOLETE, meaning it has been reclassified or merged into broader categories of autoimmune or paraneoplastic encephalitis. Key clinical features of paraneoplastic limbic encephalitis include subacute onset of short-term memory loss, confusion, seizures, psychiatric symptoms (such as anxiety, depression, irritability, and personality changes), and sleep disturbances. Patients may also experience cognitive decline and temporal lobe epilepsy. The condition is mediated by antibodies directed against neuronal antigens, which may be intracellular (e.g., anti-Hu, anti-Ma2, anti-CV2/CRMP5) or cell-surface (e.g., anti-NMDA receptor, anti-LGI1, anti-CASPR2). The type of antibody often correlates with the underlying tumor type and prognosis. Treatment focuses on addressing the underlying malignancy, as tumor removal or treatment can lead to neurological improvement. Immunotherapy, including corticosteroids, intravenous immunoglobulin (IVIg), plasma exchange, rituximab, and cyclophosphamide, is used to modulate the immune response. Prognosis varies significantly depending on the antibody type and the responsiveness of the underlying cancer to treatment. Patients with cell-surface antibodies generally have a better neurological outcome compared to those with intracellular antibodies.

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