Peer-reviewed article

Autoimmune Encephalitis in Children: Differential Characteristics and Treatment Responses in Definite and Probable Anti-N-Methyl-D-Aspartate Receptor Encephalitis.

Rocio Victoria Garcia, Andrea Savransky, Gabriela Reyes Valenzuela, Sergio Melgarejo, Juan Ignacio Luque et al. · 17 Jul 2026

Abstract

BACKGROUND: Few studies have assessed differences between probable (antibody-negative) and definite (antibody-positive) autoimmune encephalitis (AE) in pediatric patients. We aimed to compare the clinical and paraclinical features at presentation and treatment response of these two groups and identify factors associated with short-term clinical outcome. METHODS: This retrospective study included pediatric patients with presumed immune-mediated acute/subacute encephalopathy diagnosed at a single tertiary hospital. Clinical and paraclinical data were compared. RESULTS: Eighty children (52% girls) were included: 48/80 (60%) N-methyl-D-aspartate receptor antibody-positive (median age 4.9 years) and 32/80 (40%) antibody-negative (median age 7 years). Comparative results between children with definite and probable AE were as follows: high modified Rankin Scale score at presentation, 31/48 (64.6%) vs 7/32 (21.9%); second-line immunotherapy, 17 (35.4%) vs 5 (15.6%); development of AE-associated epilepsy, 13/48 (27%) with brain magnetic resonance imaging (MRI) abnormalities in 11/13 (84.6%) vs 12/32 (37.5%) with brain MRI abnormalities in 7/12 (58%); AE relapses only occurred in 7/31 (22.6%) antibody-positive patients not treated with rituximab (RTX) vs 0/17 treated with RTX, and 0/32 antibody-negative. CONCLUSIONS: Children with definite AE were more likely to be younger and have a more severe clinical presentation, relapse, and require second-line treatment, compared to children with probable AE. Lower initial modified Rankin Scale scores and early treatment initiation showed a trend toward a favorable outcome. AE-associated epilepsy was similar in both groups, with brain MRI abnormalities more frequently identified in children with definite AE. Our study highlights the relevance of early intervention with first-line immunotherapy in both groups and the benefit of RTX treatment for relapse prevention.