Value of anti-N-methyl D-aspartate receptor in children with encephalitis: a prospective observational study

BACKGROUND: Anti-N-methyl D-aspartate receptor (anti-NMDAR) encephalitis is a treatable autoimmune disorder increasingly recognized in children. We aimed to evaluate cerebrospinal fluid (CSF) anti-NMDAR antibody levels in pediatric encephalitis, and to assess their diagnostic and prognostic utility in relation to clinical, laboratory, and neuroimaging features METHODS: In this prospective observational study, 85 children with encephalitis admitted to the pediatric intensive care unit were evaluated. Patients were categorized into Group I (n = 37) with anti-NMDAR encephalitis and Group II (n = 48) with non-anti-NMDAR encephalitis. Clinical manifestations, CSF findings, Electroencephalogram (EEG), and CSF anti-NMDAR antibody levels (measured by ELISA) were analyzed. Receiver operating characteristic (ROC) curves assessed diagnostic performance RESULTS: Group I demonstrated significantly higher rates of psychiatric symptoms, seizures, abnormal movements, and speech disturbances than Group II. EEG abnormalities, particularly extreme delta brush, were more common in anti-NMDAR encephalitis. CSF anti-GluN1 antibody levels correlated positively with alanine aminotransferase(ALT), platelet count, and Glasgow Coma Scale score (GCS), and negatively with CSF neutrophils and protein. Antibody levels were significantly elevated in Group I, with ROC analysis showing high sensitivity and specificity for diagnosis CONCLUSION: CSF anti-NMDAR antibody measurement is a robust diagnostic biomarker in pediatric encephalitis. Early detection may facilitate timely immunotherapy and improve outcomes. IMPACT: This study demonstrates that CSF anti-NMDAR antibody testing improves both the diagnosis and prognosis of pediatric encephalitis. Antibody positivity was associated with distinct clinical and neuroimaging features, supporting earlier recognition and initiation of immunotherapy. Incorporating antibody testing into pediatric practice may enhance patient outcomes and advance the management of autoimmune encephalitis in children.