Whole-Brain Structural Connectivity Alterations in Chronic Subjective Tinnitus: An Exploratory Diffusion Tensor
Pınar Elpen Karyemez1, Sıla Ulus2, Eren Yılmaz3
1Department of Medical Imaging Techniques, Vocational School of Health Sciences, Acıbadem Mehmet Ali Aydınlar University, Istanbul 34752, Turkey.
Abstract:
Background/Objectives: Subjective tinnitus, the underlying mechanism of which remains largely unknown, accounts for the majority of cases. Although conventional MRI and audiometric assessments demonstrate limited effectiveness in identifying organic causes, advanced microstructural techniques-such as diffusion tensor imaging (DTI) and fiber tractography-facilitate the evaluation of microanatomical connectivity related to auditory processing. This study employed DTI to examine alterations in microanatomical brain connectivity in patients with chronic subjective tinnitus, in comparison to a healthy control group. Methods: This study performed a comparative analysis of whole-brain connectivity maps, derived from Diffusion Tensor Imaging, between 47 patients with chronic subjective tinnitus (symptom duration ≥ 2 years) and 42 healthy controls. To ensure a robust assessment of micro-anatomical neural connectivity, DTI datasets were processed using the DSI Studio platform, with anatomical regions systematically mapped using automatic anatomical labeling atlases. Specifically, these metrics were evaluated across nodes in the central auditory pathway and limbic system to identify potential disruptions in structural integrity. Results: The comparative analysis revealed significant micro-anatomical connectivity alterations in patients with chronic subjective tinnitus. Changes in structural integrity were observed predominantly across key nodes within the central auditory pathway and limbic system, specifically involving the frontal, submarginal, cingular, insular, parietal, precuneus, cuneus, amygdala, thalamus, supplementary motor area, and precentral regions. Conclusions: Chronic subjective tinnitus was associated with a distinct, largely asymmetrical pattern of whole-brain structural connectivity, predominantly involving nodes of the salience, default-mode, and central-executive networks. Because behavioral, audiometric, and cognitive measures were not acquired, these findings are exploratory and hypothesis-generating; their cognitive and occupational relevance will require confirmation in studies that combine connectivity mapping with direct behavioral and audiological testing.
