Autoimmune encephalitis in Latin America. Clinical features and outcomes in pediatric and adult populations: Retrospective cohort of The REAL LABIC Project

Miguel A. Vences^1*Christoper A. Alarcon Ruiz²Mary Marcela Araujo Chumacero³Diego Canales – Pichen³Victor Saquisela³Jesús Domínguez-Rojas⁴Donoband Melgarejo⁵Saúl Reyes-Niño⁶Cintia Johnston⁷Maricela García-Arellano⁸MERCEDES AMNELY SUAREZ LORO³Cibele Lopes Queiroz de Lima⁹José Domingo Barrientos Guerra¹⁰Vanessa Cristina Waetge Pires de Godoy⁷William Bayona Pancorbo¹¹Carla Gabriela Román Ojeda¹¹Stefany Espinoza-Ramon³Karen Perales¹²Katya Granela¹³Jorge Flecha⁵Marlene Romero⁵Habib Georges Moutran Barroso⁶Jaime Toro⁶Werther Brunow Carvalho⁷Miguel Ángel Pelcastre Mejía⁸Kátia Yuri Xavier Mizumoto Soares⁹Ana Beatriz Sonta-Chan¹⁰Alejandra Gramajo-Juárez¹⁰Victor Edwin Ore Montalvo¹¹Silvia Fabiola García Martínez¹⁰Belkis de la Candelaria¹³Daniel Agustin Godoy¹⁴

• ¹Universidad Cesar Vallejo Piura, Piura, Peru
• ²Universidad San Ignacio de Loyola, Lima District, Peru
• ³Hospital Nacional Edgardo Rebagliati Martins, Lima District, Peru
• ⁴Instituto Nacional de Salud del Nino, Lima District, Peru
• ⁵Hospital Central del Instituto de Prevision Social Dr Emilio Cubas, Asunción, Paraguay
• ⁶Fundacion Santa Fe de Bogota, Bogotá, Colombia
• ⁷Universidade de Sao Paulo, São Paulo, Brazil
• ⁸Centenario Hospital Miguel Hidalgo., Aguascalientes, Mexico
• ⁹Hospital infantil Cândido Fontoura., São Paulo, Brazil
• ¹⁰Hospital General San Juan de Dios, Guatemala City, Guatemala
• ¹¹Hospital Nacional Adolfo Guevara Velasco, Essalud., Cusco, Peru
• ¹²Organización Clínica General del Norte de la Ciudad de Barranquilla Atlántico, Baranquilla, Colombia
• ¹³Clinica General del Norte, Barranquilla, Colombia
• ¹⁴Sanatório Pasteur, Catamarca, Argentina

The Autoimmune Encephalitis Registry in Latin American countries (REAL LABIC Project) is an initiative created to conduct research focused on the epidemiological and clinical aspects of autoimmune encephalitis (AE) in the region. This study describes the sociodemographic profile, clinical presentation, treatment, and follow-up outcomes of patients diagnosed with AE across multiple reference centers from Latin America. Methods: A retrospective, multicenter cohort study was conducted in 10 hospitals across 6 countries from Latin America. Medical records of pediatric and adult patients hospitalized between July 2017 to June 2022 were reviewed. Inclusion criteria were diagnostic of probable or definite AE according to consensus diagnostic criteria by Graus et al. Comparative analyses were performed between pediatric and adult groups using hypothesis contrast tests.The study included 165 patients, 57.6% were under 18 years of age. Confirmed antibody-mediated AE was more frequent in pediatric patients, with anti-NMDA receptor antibodies identified in 53.5% of cases (CSF/serum). The median time from symptom onset to hospital admission was 8 days, significantly shorter in pediatrics (p = 0.027). A preceding viral prodrome was more common also in pediatrics (p = 0.003). ICU admission was required in 53.9% of cases, predominantly among pediatrics (p = 0.011). First-line immunotherapy was administered in 92.1% of patients, most commonly combining corticosteroids and intravenous immunoglobulin. Early initiation of treatment (≤7 days) was associated with better response in pediatrics. At six-month follow-up, 45.5% of patients showed persistent neurological disability (mRS:2-5). Minor cognitive impairment was the most frequent long-term sequela. In-hospital complications were reported in 53.3% of cases, and the overall mortality rate was 19.4%. Conclusion: This is the first regional multicenter study of autoimmune encephalitis in Latin America highlighting the above findings.The findings presents the first regional multicenter study of patients diagnosed with autoimmune encephalitis in Latin America. There wereas no significant differences in the mostmost of the analyzed variables between pediatric and adult populations. Future research should address the strengths and limitations of this registry with the aim to gainof gaining a broader understanding of autoimmune encephalitis in our region.