Voltage-Gated Potassium Channel-Complex Antibody-Associated Limbic Encephalitis

Abstract

Limbic encephalitis is characterized by the subacute progression of short-term memory loss, disorientation, confusion, and agitation. Hallucinations, behavioral and personality changes, temporolimbic seizures, sleep disturbances, and dysautonomia may also occur. The pyramidal layer of the hippocampus and the amygdaloid nuclei are particularly susceptible and demonstrate neuronal loss, reactive gliosis, and perivascular lymphocytic cuffing. Magnetic resonance imaging (MRI) typically reveals increased signal in limbic structures on T2, fluid-attenuated inversion recovery (FLAIR), and diffusion-weighted imaging (DWI). Historically, limbic encephalitis has been conceptualized as a paraneoplastic process characterized by autoantibodies associated with underlying neoplasms: small cell lung, lymphoma, thymoma, testicular, breast, teratoma, prostate, rectal, retinoblastoma, oligodendroglioma, melanoma, and leiomyosarcoma. Although a definitive pathophysiologic mechanism for autoimmune limbic encephalitis remains unknown, multiple autoantibodies are implicated, including voltage-gated potassium channel complex antibodies (VGKC-complex Ab.) Idiopathic autoimmune limbic encephalitis also occurs. We present the longitudinal course of a man who developed cognitive and behavioral disturbances ultimately attributed to VGKC complex autoimmunity.