Immunotherapy for anti-NMDA receptor encephalitis: Experience from a single center in Taiwan

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is an anti-neuronal antibody-mediated inflammatory brain disease that causes severe psychiatric and neurological deficits in previously healthy patients. The aims of this study were to demonstrate the clinical characteristics of patients diagnosed with anti-NMDA receptor encephalitis and to compare the different treatment strategies among these patients.

Patients presenting with newly acquired psychiatric and/or neurological deficits were studied retrospectively from 2009 to 2017. Patients with evidence of anti-NMDA receptor antibodies in serum and/or cerebrospinal fluid were enrolled. The modified Rankin scale was used to assess the initial status and outcomes of the enrolled patients. Details of the clinical presentations and results of investigations were analyzed.

All (n = 24) of the patients received first-line immunotherapy (steroids, and/or intravenous immunoglobulin, and/or plasma exchange), and 14 patients received second-line immunotherapy (rituximab and/or cyclophosphamide). The mean time between the first- and second-line treatment was 13 days. During the first 6 months, 20 patients (20/24, 83%) achieved a good outcome (modified Rankin Scale score ≤2) and 15 patients (15/24, 62.5%) completely recovered. Four patients (17.7%) relapsed, and three patients (12.5%) had associated tumors.

Immunotherapy is an effective treatment for anti-NMDA receptor encephalitis. Rituximab and/or cyclophosphamide are treatment options for those who cannot tolerate or do not respond to first-line immunotherapy. Prospective studies are necessary to investigate the role of rituximab and cyclophosphamide in anti-NMDA receptor encephalitis.