Immunotherapy-responsive Non-paraneoplastic Encephalitis with Antibodies against GAD, LGI1, and GABA(A) Receptor

A 62-year-old man showed abnormal behavior. Brain magnetic resonance imaging revealed multifocal lesions on T2-weighted images. Initial screening revealed that he was seropositive for antibodies against glutamate decarboxylase, which usually indicates treatment resistance to autoimmune encephalitis (AE). Intensive immunosuppressive therapies, however, improved the neurological symptoms. In line with this, we also detected seropositivity for antibodies against leucine-rich glioma-inactivated 1 and gamma-aminobutyric acid A receptor (GABA(A)R). Brain imaging and treatment responsiveness suggested that antibodies against GABA(A)R were the main cause of symptoms. Furthermore, the patient showed the presence of triple anti-neural antibodies in the absence of malignancy and had a favorable clinical course.