Background: Anti-N-methyl D-aspartate-receptor encephalitis (anti-NMDARe) is a severe disease with a favorable outcome when immunomodulatory management is started rapidly. The main objective of this study is to compare the early efficacy of the two most frequently used therapeutics, i.e., intravenous immunoglobulin (IVIG) and therapeutic plasma exchange (TPE), in intensive care patients admitted for anti-NMDARe.
Methods: This is an observational retrospective study of patients hospitalized in a tertiary medical neurointensive care unit for severe anti-NMDARe. Patients were categorized according to the modality of first-line immunomodulatory therapies associated with corticosteroids: TPE, IVIG, or IVIG followed by TPE. The primary end point was the effectiveness of the first-line immunomodulatory treatment. Treatment was considered effective when no other immunomodulatory therapy was introduced and the patient met the following three conditions: response to simple commands, absence of epileptic seizures, and absence of abnormal movements.
Results: Thirty-seven patients were included in the study from January 2007 to December 2022: 8 were treated with TPE alone, 13 were treated with IVIG alone, and 16 were treated with IVIG followed by TPE. Of the 29 patients treated with IVIG, 13 showed improvement, with a median latency to treatment response of 36 days, whereas 16 were switched to TPE, with a median latency to treatment response of 30 days due to a lack of improvement. All eight patients treated with TPE improved, with a latency to treatment response of 31 days. TPE was significantly more effective than IVIG.
Conclusions: This study raises the hypothesis that immunotherapies may have differential response rates among patients with NMDARe. Although the retrospective nature of the analysis may be subject to bias and confounding, the potential for therapeutic impact deserves prospective evaluation.