Evaluation of white matter integrity by usingdiffusion tensor imaging in patients with presbycusis

Objective: This study aims to evaluate the white matter integrity in individuals diagnosed with presbycusis (age-related hearing loss) using diffusion tensor imaging (DTI) and to investigate the relationship between DTI findings and the degrees of patients' hearing loss. Materials and Methods: A total of 163 individuals aged 50 and above, diagnosed with presbycusis, were included in the study. As a control group, 96 individuals with normal hearing levels from a similar age group were selected. In patients diagnosed with presbycusis and individuals in the control group, measurements of fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD) were conducted from 18 different white matter localizations in the brain, and the obtained data were compared. The patient group was divided into three groups based on pure-tone audiometry values: mild, moderate, and advanced hearing loss; DTI parameters within each group were compared. Additionally, the relationship between speech discrimination audiometry scores and DTI data was evaluated using multiple regression analysis. Findings: Statistically significant changes in white matter pathways have been observed in patients diagnosed with presbycusis. Particularly, decreases in FA values in the right and left lateral lemniscus and the anterior limb of the left internal capsule; and increases in RD values in the white matter of the left superior temporal gyrus were detected. In the intergroup comparisons made according to the severity of hearing loss, increases in ADC values in the right and left cingulum in patients with moderate and advanced hearing loss were observed, and compared to patients with mild hearing loss, decreases in FA values in the right inferior fronto-occipital fasciculus and AD values in the right lateral lemniscus were noted in patients with moderate hearing loss. Multiple regression analysis revealed significant relationships between speech discrimination skills and DTI parameters. Conclusion: This study is among the comprehensive research conducted on the assessment of white matter integrity in cases of presbycusis and aims to contribute to a deeper understanding of this condition. Our findings suggest that microstructural changes in white matter may have a potential relationship with auditory processing and speech discrimination abilities. Furthermore, our findings imply that presbycusis might affect white matter pathways that are not directly related to auditory processing. Keywords: Presbycusis, Diffusion Tensor Imaging, Hearing Loss