Characterization of the Differential Diagnoses of Autoimmune Encephalitis in Brazil: A Retrospective Study

• Grant number: 25/03110-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2025
• End date: March 31, 2026
• Field of knowledge: Health Sciences - Medicine
• Principal Investigator: Livia Almeida Dutra
• Grantee: Polyana Favero Ferreira Caetano
• Host Institution: Instituto Israelita de Ensino e Pesquisa Albert Einstein (IIEPAE). Sociedade Beneficente Israelita Brasileira Albert Einstein (SBIBAE). São Paulo , SP, Brazil

Abstract

Autoimmune encephalitis (AE) comprises a group of inflammatory diseases ofthe central nervous system (CNS), characterized by altered levels of consciousness,neuropsychiatric symptoms, movement disorders, seizures, and/or dysautonomia,typically with an acute or subacute onset. AE is an important differential diagnosis forvarious conditions commonly encountered in general hospitals, such as infectiousencephalitis, psychotic episodes, and status epilepticus epileptic seizures. The specificityof the 2016 diagnostic criteria for AE varies across populations and is estimated to rangefrom 27% to 94%. Consequently, up to 73% of patients meeting the clinical criteria forpossible autoimmune encephalitis may not actually have the disease. In 2021, adiagnostic algorithm was proposed to enhance diagnostic accuracy, improve thecharacterization of AE mimics, and introduce a new category termed PNID (probableautoimmune inflammatory disorder). AE mimics refer to well-defined conditions (such asinflammatory, genetic, or neoplastic diseases) that resemble AE, whereas PNIDencompasses a group of poorly understood, likely inflammatory diseases. In this study,we aim to review 870 cases from the BrAIN study database (a Brazilian AE cohort),collected between 2018 and 2023, and apply the new diagnostic algorithm to describeAE mimics, PNID, and their predictive variables. Our goal is to contribute to improveddiagnostic precision and clinical decision-making.