Effects of sound therapy on resting-state functional brain networks in patients with tinnitus: A graph-theoretical-based study.

BACKGROUND: Tinnitus is considered to be triggered by aberrant neural activity in the brain. Sound therapy is regarded as a reasonable management option for tinnitus treatment and has been applied in the clinical setting for decades. HYPOTHESIS: We hypothesized that sound therapy, a commonly used tinnitus treatment method, would alter the functional connectivity (FC) of brain regions in tinnitus models. STUDY TYPE: Longitudinal. POPULATION: Resting-state functional MRI data were collected from 27 tinnitus patients before and after 12 weeks of sound therapy. Twenty-seven age- and sex-matched healthy controls were also longitudinally scanned at the 12-week timepoint. FIELD STRENGTH: 3.0T MRI system and echo planar imaging (EPI) sequence, 3D brain volume imaging (BRAVO) sequence. ASSESSMENT: Functional connectivity strength (FCS), a graph-theoretical-based analytic method, was applied to analyze the FC features in the whole brain. STATISTICAL TESTS: Student's t-test and chi-square test were used for analyses between two groups. A two-way analysis of covariance (ANCOVA) followed by post-hoc analyses was performed to determine differences of FC. RESULTS: The interaction effect between the two groups and two scans on FCS was observed in the bilateral thalami and left anterior cingulate cortex (ACC). The fitted FCS values in the bilateral thalami were significantly higher in tinnitus patients at baseline and decreased to a relatively normal range after sound therapy compared with healthy controls. Conversely, the fitted FCS values in the left ACC were within the normal range, but increased after treatment (1.08 ± 0.29, P < 0.02); however, there was no change in the control group. Importantly, significant correlations were observed between the FCS changes in the right thalamus (P = 0.028), the FC of the right thalamus-right inferior frontal gyrus (P = 0.015), and symptomatic improvement. DATA CONCLUSION: Sound therapy may modulate the brain network by altering the gating function of the thalamus as well as enhancing the tinnitus-canceling system. LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 4 J. Magn. Reson. Imaging 2019;50:1731-1741.

Long-term reactions to pulsatile tinnitus are marked by weakened short-range functional connectivity within a brain network in the right temporal lobe.

BACKGROUND: There have been recent efforts to characterize brain functional activity features in patients with pulsatile tinnitus (PT). These efforts have revealed evidence of aberrant functional connectivity (FC) of the right middle temporal gyrus (MTG) in PT patients with prolonged disease duration. PURPOSE: To assess the possible predictive effect of aberrant FC of MTG in PT patients with prolonged disease duration. STUDY TYPE: Retrospective. POPULATION: Thirty-four patients with recent-onset PT (RPTIN), 24 patients with long-term PT (LPTIN), and 35 age-, gender-, and education-matched healthy controls were enrolled. FIELD STRENGTH/SEQUENCE: 3.0T MRI system and echo-planar imaging (EPI) sequence, 3D brain volume imaging (BRAVO) sequence. ASSESSMENT: Functional MRI data preprocessing was performed in Data Processing & Analysis for Brain Imaging (DPABI) and Statistical Parametric Mapping (SPM) 8. The FC analyses were conducted using the software REST. STATISTICAL TESTS: One-way analysis of covariance was conducted between three groups with age and gender as covariates, and post-hoc analysis was used to identify the sources of group effects. Pearson's correlation analysis was conducted for the z-values of altered FC strength in the PT group and the clinical data. RESULTS: Among hubs belonging to the executive control network, the default mode network (DMN), and limbic network, the strength of FC was mainly decreased in the patient groups compared with normal controls (P < 0.05). Relative to RPTIN patients and normal controls, LPTIN patients were further characterized by significantly decreased FC between several short-range brain regions adjacent to the seed (P < 0.05). Finally, disease duration was negatively correlated with decreased FC between the seed and right fusiform gyrus/parahippocampal gyrus, right inferior frontal gyrus, and right MTG (a brain area adjacent to the seed region). DATA CONCLUSION: Long-term reactions to PT mainly involved weakened short-range FC, especially within a functional network in the right temporal lobe. LEVEL OF EVIDENCE: 4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.