Infections and Anti-N-Methyl-D-Aspartate Receptor Encephalitis in Children and Adolescents: A Scoping Review of Evidence Since the COVID-19 Pandemic

Background/Objectives: Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a common autoimmune encephalitis affecting children and adolescents. Its development has been associated with preceding or concomitant infections, particularly herpes simplex virus type 1 (HSV-1). This scoping review characterized the association between infections and pediatric anti-NMDAR encephalitis, focusing on epidemiology, pathophysiology, clinical presentation, treatment, and prognosis from January 2020 to August 2025. Methods: A scoping review was conducted according to the Joanna Briggs Institute (JBI) framework. PubMed was systematically searched using the terms NMDAR encephalitis AND infections AND children. Of 110 identified records, 13 studies met the predefined eligibility criteria. Results: HSV-1 was the most consistently reported infectious association, particularly in younger children. Clinical phenotype varied with age, with neurological manifestations predominating in younger children and psychiatric, behavioral, and cognitive symptoms becoming more prominent in adolescents. HSV-associated cases, particularly following extensive HSV-related brain injury, were associated with greater residual neurological morbidity and less favorable long-term outcomes. Other infectious agents, including SARS-CoV-2, respiratory syncytial virus, influenza B, and norovirus, were reported less frequently, with limited evidence regarding their impact on disease course. Immunotherapeutic strategies were generally similar irrespective of preceding infection, although active or treatment-associated infections could influence treatment timing, sequencing, and infectious-risk considerations. Earlier immunotherapy was associated with more favorable neurological recovery. Conclusions: Infectious exposures, particularly HSV-1, appear to be associated with pediatric anti-NMDAR encephalitis, although causality cannot be established from the predominantly retrospective and case-based literature. Prospective, multicenter studies using standardized diagnostic and outcome measures are needed to clarify the infection–autoimmunity relationship and optimize early recognition and management.