Mateus Santana do Rosário, Maria Paula de Souza Sampaio, Lorena Cunha Martins, Luiza Vieira Luedy Trindade, Gabriela Farias Carreiro, Breno Pinheiro de Almeida Franco e Castro, Bernardo Gratival Gouvea Costa, Gessica Almeida Vasconcelos, Jesângeli de Sousa Dias, Alan Oliveira Duarte, Mohammed Habib, Cássia Flávia Moreira Souza, Pedro Sampaio Almeida Ramos Conceição, Mariellen Santos de Jesus Souza, Pedro Antônio Pereira de Jesus, Daniel Santana Farias, Murilo Santos Souza, Adilson Junior Pinto Galvão, Felipe Oliveira Costa, Tarsis Leonardo Almeida Farias, Jamary Oliveira‐Filho, Thiago Gonçalves Fukuda, Celia Silvany, Janeusa Rita Leite Primo Chagas, José Teles, Gúbio Soares Campos, Sílvia Inês Sardi, Ively Paixão Santos, Ricardo Khouri, Marcia Carvalho Bessa, Maricélia Maia de Lima, Tiago Gräf, Isadora Cristina de Siqueira
OBJECTIVES: To characterize the clinical, epidemiological, and laboratory spectrum of acute viral-associated neurological syndromes in an arbovirus-endemic region of northeastern Brazil. METHODS: We conducted a prospective, hospital-based cohort (March 2020 to August 2025) including patients with suspected viral neurological syndromes. Systematic testing combined qRT-PCR and serology for arboviruses (CHIKV, DENV, ZIKV, OROV) with multiplex PCR for classical neurotropic viruses. Clinical, imaging, EEG, and ENMG data were collected using standardized electronic forms. Temporal and seasonal trends were analyzed using quasi-Poisson and cyclic generalized additive models. RESULTS: Among 132 patients, encephalitis (58%, 76/132) and Guillain-Barré syndrome (23%, 30/132) predominated. A viral etiology was identified in 42% (56/132), mostly arboviral. CHIKV (41%, 23/56) was the most frequent pathogen, followed by DENV (26%, 15/56) and OROV (11%, 6/56%), while HSV-1 was rare. GBS showed a significant upward trend and seasonal pattern, contrasting with stable encephalitis incidence. CSF, imaging, and electrophysiological findings were heterogeneous, reflecting complex diagnostic patterns. CONCLUSIONS: Arboviruses-particularly CHIKV, DENV, and emerging OROV-are leading causes of acute neurological syndromes in Brazil. The integration of multiplex viral panels and arboviral assays is essential to enhance diagnosis. Strengthened surveillance and molecular diagnostics are critical in regions with arboviral circulation.