The objective of this study is to describe the treatment and outcome of children and adolescents with N-methyl-D-aspartate receptor (NMDA-R) encephalitis. A retrospective study of children and adolescents with NMDA-R encephalitis was performed by the French Paraneoplastic Neurological Syndrome Reference Center between January 1, 2007 and December 31, 2012. The modified Rankin scale (mRS) was used to assess outcome. Thirty-six children and adolescents with NMDA-R encephalitis were studied. All of the patients received first-line immunotherapy (corticosteroids, intravenous immunoglobulins or plasma exchange), and 81% received second-line immunotherapy (rituximab or cyclophosphamide). Median time between first-line and second-line treatment was 26 days. During the first 24 months, 30 of 36 patients (83%) achieved a good outcome (mRS ≤ 2) and 20 of 36 patients (56%) achieved complete recovery (mRS = 0). Median time to good outcome and to complete recovery was 6 and 24 months, respectively. Three patients (8%) relapsed, one patient died. In multivariate analysis, age >12 years was a predictor of good outcome and initial mRS ≤ 3 was a predictor of complete recovery. Despite a higher rate of patients who received second-line immunotherapy, the outcome of the patients in the present series was very similar to the outcome reported in previous series. The present study highlights the need for clinical trials to determine the optimal treatment of NMDA-R encephalitis.

In children, as in adults, Hu-Abs can be a marker of PNS. However, in contrast to adults, Hu-Abs in children are also associated with an aggressive form of autoimmune nonparaneoplastic limbic encephalitis. Future studies should be conducted to determine the incidence of this syndrome and whether earlier diagnosis and T-cell-directed immunotherapies may improve its prognosis.