Clinical profile and long term outcome of the Japanese patients with NMDAR-encephalitis (P1.334)

Objective: To evaluate the clinical features and prognosis of Japanese patients with NMDAR encephalitis under therapeutic conditions mostly limited to first-line immunotherapy. Background: NMDAR encephalitis shows characteristic clinical features with psychiatric symptoms followed by seizures, dyskinesia, autonomic failure, etc. and is mostly seen in young women. Prognosis is generally good with 70% of patients having favorable recovery after early administration of second-line immunotherapy. Because of health insurance limitations, most Japanese NMDAR encephalitis patients receive only first-line immunotherapy. We aimed to assess the clinical process of Japanese patients with NMDAR encephalitis. Design/Methods: Anti-NMDAR antibodies were tested in a cell-based assay using GluN1 and GluN2B co-transfected HEK-293 cells and immunofluorescence staining. During 2009–2014, 255 antibody-positive cases were detected. Clinical features, treatments, and outcomes after a mean period of 4 years were obtained using a questionnaire completed by doctors. Results: In total, 177 doctors completed the questionnaire (recovery rate, 66.7%). Mean onset age was 31.5 ± 16.9, 84% of the patients were women, 95.2% mainly presented psychiatric symptoms, 70.9% had seizures, 40.0% had autonomic failure, and 27.9% presented with ovarian teratoma. Tumor resection and/or first-line immunotherapies were effective in 53% of the patients. Patients 15 years. Approximately 30% of the patients with limited symptoms (mainly psychiatric or seizures) were not given immunotherapy; among these, only 8% returned to their daily work. It took longer for patients 15 years. Conclusions: Most patients aged 15–60 years showed typical clinical features of NMDAR encephalitis; only 40% of them favorably recovered after the first-line immunotherapy. Patients 60 years tended to show partial symptoms and needed longer recovery times than those aged 15–60 years. Study Supported by: This study was supported in part by JSPS KAKENHI grants (No.23500455, 23249048), Japan (Tanaka, K.). Technical and secretarial assistance was by Y. Kitagawa and K. Hori. Disclosure: Dr. Tanaka has nothing to disclose. Dr. Tanaka has received personal compensation for activities with Bayer, Biogen Idec, and Novartis as a scientific advisory board member or speaker. Dr. Tsutsui has nothing to disclose. Dr. Sakimura has nothing to disclose.