Contents lists available at ScienceDirect Multiple Sclerosis and Related Disorders journal homepage: www.elsevier.com/locate/msard Original article Acute optic nerve lesions in frst-ever NMOSD-related optic neuritis using conventional brain MRI: A Latin American multicenter study Edgar Carnero Contentti a, ⁎ , Guillermo Delgado-García b,c , Pablo A. López a , Juan Criniti a , Juan Pablo Pettinicchi a , Edgar Patricio Correa-Díaz d,e , Ibis Soto de Castillo f , Vanessa Daccach Marques g , Verónica Tkachuk h , Edgardo Cristiano i , Gabriel Serva Braga Diéguez g , Antonio Carlos dos Santos g , María C. Castillo f , Liliana Patrucco i , Marcelo Oswaldo Álvarez Pucha e , Joselyn Elizabeth Miño Zambrano j , Enrique Gómez-Figueroa k , Verónica Rivas-Alonso k , José Flores-Rivera b,k,l , Alejandro Caride a , Juan Ignacio Rojas i a Neuroimmunology Unit, Department of Neuroscience, Hospital Alemán, Buenos Aires, Argentina b Clinical Laboratory of Neurodegenerative Diseases, National Institute of Neurology and Neurosurgery, Mexico City, Mexico c Programa de Maestría y Doctorado en Ciencias Médicas, Odontológicas y de la Salud (PMDCMOS), Universidad Nacional Autónoma de México, Mexico City, Mexico d Universidad Central del Ecuador e Pontificia Universidad Católica del Ecuador f Neurology Department, Hospital Universitario de Maracaibo, Maracaibo, Bolivarian Republic of Venezuela g Department of Neurosciences and Behavioral Sciences, Hospital das Clínicas, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil h Neuroimmunology Section, Department of Neurology, Hospital de Clínicas “José de San Martín”, Buenos Aires, Argentina i Centro de Esclerosis Múltiple de Buenos Aires (CEMBA), Buenos Aires, Argentina j Hospital Carlos Andrade Marín, Quito, Ecuador k Demyelinating Diseases Clinic, National Institute of Neurology and Neurosurgery, Mexico City, Mexico l Division of Neurology, National Institute of Neurology and Neurosurgery, Mexico City, Mexico ARTICLEINFO Keywords: Latin America population neuromyelitis optica spectrum disorders optic neuritis, optic neuritis lesions, conventional MRI, visual prognosis ABSTRACT Background: Few studies regarding MRI-defned acute optic nerve lesions (aONL) in patients with frst-ever neuromyelitis optica spectrum disorder (NMOSD)-related optic neuritis (ON) have been reported worldwide and none of them was conducted in Latin America (LATAM). Therefore, we aimed to assess the frequency of aONL at disease onset using conventional brain MRI in LATAM. Methods: We reviewed the medical records and brain MRIs (≤30 days from ON onset) of patients with ON as frst lifetime NMOSD attack. Patients from Argentina (n=48), Ecuador (n=24), Brazil (n=22), Venezuela (n=10) and Mexico (n=8) were included, and further divided into two subgroups according to either presence (P-MRI) or absence (A-MRI) of aONL (T2 hyperintensity and/or contrast enhancement). Clinical, paraclinical, imaging and prognostic data were compared. Results: A total of 112 patients were included and aONL were found in 86 (76.7%) at disease onset. Aquaporin-4 antibodies were detected in 69.6%. Non-Caucasian patients comprised 59.8% of the total cohort. In P-MRI, conventional brain MRI showed isolated or combined unilateral (54.4%, [8.5% of these aONL were associated with chiasmatic lesions]) and bilateral (46.6%, [35.9% of these aONL were associated with chiasmatic lesions]) lesions. Thus, 100% of chiasmatic lesions were associated with unilateral or bilateral lesions. No statistically signifcant diferences were found in age, gender, ethnicity, clinical course, mean follow-up time, disability, and spinal cord MRI fndings. However, rituximab use was higher in P-MRI than in A-MRI (p=0.006). Conclusions: More than three quarters of LATAM patients with frst-ever NMOSD-related ON have aONL detected by brain MRI. Unilateral lesions were the most common fnding. Further studies including diferent ethnicities are needed to assess the generalizability of our results. https://doi.org/10.1016/j.msard.2020.102558 Received 20 August 2020; Received in revised form 12 September 2020; Accepted 1 October 2020 ⁎ Corresponding author: Dr. Edgar Carnero Contentti, Neuroimmunology Unit, Department of Neuroscience, Hospital Alemán, Buenos Aires, Argentina. Av Pueyrredón 1640, C1118AAT, Buenos Aires, Argentina. E-mail addresses: junior.carnero@hotmail.com, ecarnerocontentti@hospitalaleman.com (E. Carnero Contentti). Multiple Sclerosis and Related Disorders 46 (2020) 102558 2211-0348/ © 2020 Elsevier B.V. All rights reserved. T