Anti-glutamic Acid Decarboxylase Limbic Encephalitis

Abstract

Anti-glutamic acid decarboxylase antibody-associated limbic encephalitis (AGADE) is a nonclassic antibody-mediated disease that typically manifests with psychiatric symptoms and seizures in the pediatric population. Glutamic acid decarboxylase (GAD) is highly expressed in the hippocampus and pancreas, which is thought to explain why AGADE tends to also be associated with several endocrine disorders, such as type I diabetes mellitus. The clinical significance of elevated GAD antibodies is still being debated. Nevertheless, if a relevant patient is found to have elevated GAD antibodies, then GABA-A and GABA-B antibodies should also be tested in order to guide with prognosis. IV steroids, IVIG, and plasmapheresis are first-line treatment options. However, immunomodulating agents are often required; rituximab may have the best long-term results. Despite aggressive treatment, unfortunately, most children with AGADE will continue to have symptoms years after diagnosis.