Sinaptopatia coclear relacionada à idade em ratos: o uso do potencial evocado auditivo de tronco encefálico

Abstract

In the natural aging process, there is a reduction in synapses between the inner hair cells of the organ of Corti and the neurons of the spiral ganglion in the auditory nerve, a phenomenon known as cochlear synaptopathy (CS). Studies suggest that shortlatency auditory evoked potentials (AEPs) can identify CS, but there are still gaps in the protocols and parameters used for its identification in clinical settings. Objective: To evaluate the use of short-latency AEPs in identifying age-related CS in rodents. Method: Two studies were conducted. The first was a systematic review with a metaanalysis, registered in PROSPERO (CRD42025615318), aiming to synthesize data on the accuracy of short-latency AEPs in identifying CS in aging rodents. The review followed the Preferred Reporting Items for a Systematic Review and Meta-analysis of Diagnostic Test Accuracy Studies (PRISMA-DTA) guidelines, searching the PUBMED/MEDLINE, Cochrane Library, Scopus, Embase, Web of Science, Scielo, LILACS databases, and gray literature. Article selection was performed independently and blindly by two reviewers, using the Rayyan and EndNote tools. No restrictions were applied regarding publication period or language. The second study was a crosssectional observational study, approved by the Animal Use Ethics Committee (2024- 02-ISD). Ten healthy Wistar rats of both sexes, with no prior noise exposure, were divided into age groups: G1 (3–4 months), G2 (10 months), G3 (14–15 months), and G4 (24 months). The animals underwent Auditory Brainstem Response (ABR) recording with click stimuli, alternating polarity at 90, 85, and 80 dBnHL, and stimulation rates of 33.1, 15.1, and 7.1 clicks/s. The amplitudes of waves I and IV were blindly analyzed by two specialists. Data were subjected to descriptive and inferential statistical analysis using IBM Statistical Package for the Social Sciences (SPSS), with a significance level of p<0.05. Results: In Study 1, 2,821 articles were identified, of which 15 were included in the systematic review, and seven were suitable for metaanalysis. All studies used the ABR to identify CS, with wave I amplitude being the most frequently reported biomarker. In Study 2, inter-examiner agreement was excellent (>90%). The mean amplitude was 1.33±0.69μV for wave I and 0.75±0.62μV for wave IV. There was an influence of sex, age, and stimulation rate, with wave I showing greater amplitude at 7.1 clicks/s compared to 33.1 clicks/s. Conclusion: The ABR demonstrated diagnostic performance in identifying SC in rodents, with the amplitude of wave I as a relevant biomarker and a clear effect of the stimulation rate. The findings reinforce the use of click-evoked ABR in SC investigation and provide support for future studies.