OBSOLETE: Limbic encephalitis with caspr2 antibodies

Limbic encephalitis with CASPR2 (contactin-associated protein-like 2) antibodies is an autoimmune neurological condition in which the body's immune system produces antibodies against the CASPR2 protein, a component of the voltage-gated potassium channel (VGKC) complex found on nerve cells. This condition is now classified as an obsolete entity in Orphanet (code 276402), as it has been reclassified under the broader category of autoimmune encephalitis associated with antibodies against cell-surface antigens, specifically anti-CASPR2 antibody-associated disorders. The disease primarily affects the limbic system of the brain, which is involved in memory, emotion, and behavior. Patients typically present with memory impairment, confusion, seizures (often temporal lobe epilepsy), psychiatric symptoms including personality changes, anxiety, and hallucinations, as well as sleep disturbances. CASPR2 antibody-associated disease can also manifest with peripheral nerve hyperexcitability (neuromyotonia), neuropathic pain, and autonomic dysfunction, sometimes overlapping with Morvan syndrome. The condition predominantly affects adult males, and in some cases it may be associated with an underlying tumor (paraneoplastic), particularly thymoma. Treatment involves immunotherapy, including corticosteroids, intravenous immunoglobulin (IVIg), and plasma exchange as first-line therapies. In refractory cases, second-line immunosuppressive agents such as rituximab or cyclophosphamide may be used. If a tumor is identified, its removal is an essential part of management. Early diagnosis and treatment are associated with better neurological outcomes, though some patients may experience residual cognitive deficits.

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