Pediatric autoimmune encephalitis: diagnostic delay and long-term neurocognitive outcomes - a narrative review
Autoimmune encephalitis (AE) is an increasingly recognised cause of subacute encephalopathy, behavioural change, seizures, and movement disorders in children. The recognition of antibody-mediated syndromes—principally anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis—has transformed the field, and refined diagnostic criteria now allow earlier treatment initiation. However, diagnostic delay remains common in paediatric practice and contributes to long-term neurocognitive morbidity. We review the contemporary spectrum of paediatric autoimmune encephalitis, including anti-NMDAR encephalitis, MOG antibody-associated disease overlap syndromes, and seronegative AE phenotypes, with emphasis on early recognition, diagnostic algorithms, immunotherapy, and long-term outcomes. Anti-NMDAR encephalitis is the most frequent paediatric AE worldwide, characterised by behavioural change, language regression, seizures, dyskinesias, and autonomic instability; ovarian teratoma is uncommon in prepubertal children. MOG antibody-associated disease can present with encephalopathy, particularly in younger children, often with concurrent demyelinating features. Seronegative AE poses particular diagnostic challenges. Across cohorts, diagnostic delay is associated with worse outcomes, more relapses, and persistent cognitive, behavioural, and academic difficulties. Earlier recognition through clinician education, paediatric-specific diagnostic algorithms, and rapid antibody testing pathways is essential. Long-term neurocognitive surveillance and individualised rehabilitation are critical, even in children with apparently good motor recovery. Research priorities include validation of paediatric-specific diagnostic criteria, biomarker-guided immunotherapy escalation, and population-based cohorts capturing developmental trajectories.