Neural Mechanisms of Tinnitus:An Exploration from the Perspective of Varying Severity Levels.

Abstract

Objective: To compare the brain functional changes in tinnitus patients of varying severities, in order to elucidate the complex relationship between tinnitus symptoms and neural mechanisms, providing a basis for personalized treatment for tinnitus patients with varying severity levels.

Method: 62 patients with chronic tinnitus were divided into severe and mild tinnitus group. 31 healthy controls (HC) matched for age, gender and education level were included. Resting-state functional magnetic resonance imaging was performed for all subjects, and the values of regional homogeneity (ReHo), amplitude of low-frequency fluctuation (ALFF), fractional ALFF (fALFF) and functional connectivity (FC) were calculated. One-way analysis of variance (ANOVA) was used to compare the differences among the three groups. Correlational analysis was conducted between imaging metrics and clinical information.

Results: Compared to the mild tinnitus, the severe tinnitus shows increased ReHo and ALFF values in the left superior temporal gyrus (STG), middle temporal gyrus (MTG), supramarginal gyrus (SMG), angular gyrus (ANG), and middle occipital gyrus (MOG), as well as increased ReHo values in the left superior frontal gyrus (SFG) and ALFF values in the right ANG. In the severe tinnitus group, the FC between the bilateral ANG and the left MTG, the right ANG and the right medial SFG, the right ANG and the right anterior cingulate gyrus (ACG), as well as between the left SFG and the left rectus gyrus, was increased compared to the mild tinnitus group. In mild tinnitus group, the ReHo of left STG is correlated with tinnitus severity by Tinnitus Handicap Inventory.

Conclusion: Patients with different severity of tinnitus exhibit different compensatory mechanisms in brain function, highlighting the need for stratified analysis based on severity when investigating the underlying neural mechanisms.