Anti-Ri-related Possible Autoimmune Encephalitis may Cause Intellectual and Developmental Disabilities in Pediatric Patients: A Case Report

Abstract Objective: To describe two rare pediatric cases in which anti-Ri autoantibody-positive (Type II anti-neuronal nuclear antibody; ANNA-2-positive) autoimmune encephalitis occurred with intellectual and development disabilities.. Case presentation: We presented the clinical manifestations, etiological evaluation, and intellectual assessment of two ANNA-2-positive children and the clinical improvement after empirical immunotherapy. A 2-year-old girl with hyperactivity, agitation, and hand tremors and a 6-month-old boy who had dystonia were both diagnosed with intellectual and development disability. Both children tested positive for ANNA-2 and the serological inflammatory markers. Considering possible Ri antibody associated autoimmune encephalitis, empirical immunotherapy was done for both patients, intellectual disability of them improved to some extent. Conclusions: Although ANNA-2 has been mostly reported in adults with paraneoplastic syndrome, we report two ANNA-2-positive pediatric cases diagnosed as possible autoimmune encephalitis due to viral infections. These cases suggested that disruption of the immune system due to viral infection may lead to ANNA-2 positive status and contribute to intellectual and development disability in pediatric cases.