Anti-γ-aminobutyric acid type A receptor encephalitis: a new type of autoimmune encephalitis with prominent epilepsy

Abstract

Objective To firstly report the clinical features, diagnosis and treatment response of patients with anti-γ-aminobutyric acid type A receptor (GABAAR) encephalitis in China, thus raising neurologists′ awareness of this emerging type of autoimmune encephalitis. Methods Specific anti-GABAAR autoantibodies in the serum and cerebrospinal fluid (CSF) of patients with suspected autoimmune encephalitis but negative for commercial available antibody tests were detected by live cell-based assay (CBA). The clinical features, laboratory examinations and treatment of two cases of autoimmune encephalitis with anti-GABAAR autoantibodies were analyzed, who admitted to Huashan Hospital, Fudan University between 2013 and 2014. Results By using live CBA, serum and CSF of the two patients diagnosed with possible autoimmune encephalitis both contained autoantibodies targeted to the GABAAR. These two patients had onset symptom of seizure or refractory seizures. Memory impairment, psychiatric symptoms and decreased consciousness were also presented. One patient was combined with mass in anterior superior mediastinum. Both patients had multifocal cortical and subcortical T2/fluid attenuated inversion recovery-weighted images hyperintensity signal on brain magnetic resonance imaging. The two patients had poor response to antiepileptic drugs, but showed noticeable recovery with sufficient immunotherapeutic treatments. Conclusions Anti-GABAAR encephalitis is characterized by prominent epilepsy and multifocal abnormalities on brain magnetic resonance imaging. Autoantibodies specifically against GABAAR could be detected by CBA in this group of patients. Early diagnosis and immunotherapy are critical to improve clinical symptoms and outcomes of the disease. Key words: gamma-Aminobutyric acid; Autoantibodies; Autoimmune encephalitis; Epilepsy