OBSOLETE: Limbic encephalitis with LGI1 antibodies

Limbic encephalitis with LGI1 antibodies (also known as anti-LGI1 encephalitis or autoimmune limbic encephalitis associated with leucine-rich glioma-inactivated 1 antibodies) is an autoimmune neurological disorder in which the body produces antibodies against the LGI1 protein, a component of the voltage-gated potassium channel complex. This condition primarily affects the limbic system of the brain, which is involved in memory, emotion, and behavior. Note that this Orphanet entry (163908) is designated as OBSOLETE, as the condition has been reclassified or merged into broader categories of autoimmune encephalitis. The disease predominantly affects adults, typically in their 50s to 60s, and presents with subacute onset of cognitive impairment (particularly short-term memory loss), seizures (including characteristic faciobrachial dystonic seizures), psychiatric symptoms such as confusion and personality changes, and hyponatremia (low sodium levels in the blood). Faciobrachial dystonic seizures, which are brief involuntary movements of the face and arm on the same side, are considered highly characteristic and may precede the full development of limbic encephalitis. Treatment involves immunotherapy, including first-line therapies such as corticosteroids, intravenous immunoglobulin (IVIG), and plasma exchange. Second-line treatments such as rituximab or cyclophosphamide may be used in refractory cases. Early recognition and prompt initiation of immunotherapy are associated with better outcomes. Many patients show significant improvement with treatment, though some may experience residual cognitive deficits. Unlike some other forms of autoimmune encephalitis, anti-LGI1 encephalitis is only rarely associated with an underlying tumor (paraneoplastic origin).

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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