Aberrant Topological Properties Of Whole-brain Functional Network In Chronic Unilateral Sensorineural Hearing Loss:a Resting-State Functional MRI Study

Objective Previous studies have indicated that the USNHL-related impairments existed in some local brain regions. Here, we applied a graph-theoretical analysis to resting-state fMRI data to investigate the topological properties of the functional brain network in patients with right-sided hearing loss.Methods In this study, we acquired resting-state BOLD-fMRI (rsfMRI) data from 19 right-sided SNHL patients and 31 healthy controls with normal hearing and constructed their whole brain functional networks. Two-sample two-tailed t-tests were performed to investigate group differences in topological parameters using graph theory method. Nodal properties were corrected by multiple comparisons. Partial correlation analysis was conducted to determine the relationships between the network metrics and USNHL-related clinical variables.Results Both USNHL patients and controls exhibited small-word architecture in their brain functional networks within the range 0.1～0.2 of sparsity. Compared to the controls, USNHL patients showed significant increase in characteristic path length and normalized characteristic path length, but significant decrease in global efficiency. Clustering coefficient, local efficiency and normalized clustering coefficient demonstrated no significant difference. The USNHL showed significantly increased betweenness centrality primarily in left supramarginal gyrus and right fusiform. While other nodal parameters demonstrated no difference. Analyses of local metrics revealed a significantly altered organization of the hub nodes in USNHL, as shown by analyses of hub disruption indices using betwenness and by a loss of "hubness" in several nodes. Furthermore, USNHL patients exhibited no significant association between the altered network metrics and the duration of USNHL or the severity of hearing loss.Conclusion Our results indicated the altered global and nodal properties of whole brain functional networks in right-sided SNHL patients, which may help us to understand pathophysiologic mechanism of USNHL patients.