The impact of hearing loss on tinnitus-related brain reorganization: evidence from multimodal resting-state functional magnetic resonance imaging.

BACKGROUND

Whether hearing loss fundamentally alters tinnitus-related brain reorganization remains unclear. To address this issue, this study compared features from multimodal resting-state functional magnetic resonance imaging (rs-fMRI) between tinnitus patients with hearing loss (TIN + HL) and those without hearing loss (TIN - HL).

METHODS

A total of 38 patients with tinnitus (23 TIN + HL and 15 TIN - HL) and 28 healthy controls (HCs) underwent rs-fMRI. Amplitude of low-frequency fluctuations (ALFF), regional homogeneity (ReHo), and bilateral auditory cortex (AC)-based functional connectivity (FC) were compared among groups via one-way analysis of variance (ANOVA) and post hoc t tests. Correlations with clinical characteristics were examined via partial correlation.

RESULTS

Compared with the HC group, both tinnitus groups exhibited decreased ALFF in the bilateral anterior cingulate cortex (ACC), along with increased ALFF and decreased ReHo in the left middle occipital gyrus (MOG) [cluster-level family-wise error (FWE)-corrected P<0.05]. Additionally, the TIN + HL group showed decreased ALFF in the bilateral caudate nucleus (CN) and decreased ReHo in the right parahippocampal gyrus (PHG) and middle frontal gyrus (MFG), while the TIN - HL group exhibited decreased ReHo in the right rectus gyrus. Compared with the HC group, both tinnitus groups showed reduced FC between the right AC and the left superior temporal gyrus (STG), with more pronounced reduction in the TIN - HL group (P<0.05, Bonferroni correction). The ALFF in left MOG negatively correlated with the depression scores in the tinnitus groups (r=-0.513; P=0.001).

CONCLUSIONS

Hearing loss may differentially shape tinnitus-related brain reorganization. Although both subtypes shared common alterations in limbic and visual association regions, TIN + HL appears to be characterized by disruptions in sensory gating and cognitive control circuits, whereas TIN - HL may involve emotion-regulation network alterations and more pronounced auditory network disconnection. These findings provide a neuroimaging basis for subtype-specific treatment.