Pediatric anti-NMDA receptor encephalitis is seasonal.

In the majority of pediatric anti-N-methyl-d-aspartate receptor encephalitis (NMDARe) cases, the underlying cause of antibody production and subsequent disease remains unknown. We aimed to characterize this poorly understood population, investigating epidemiological factors potentially related to disease etiology, particularly season of onset. In this retrospective case review study, we analyzed data from the 29 pediatric subjects with anti-NMDAR antibodies and found that symptoms were first reported in the warm months of April-September in 78% of non-tumor-related NMDARe (NT-NMDARe) cases. These findings support further investigation into a possible seasonal trigger of NT-NMDARe.