Disrupted Topological Organization in White Matter Networks in Unilateral Sudden Sensorineural Hearing Loss.

Yan Zou,Siqi Wang,Bo Liu,Ping Han,Xinrong Wang,Dan Li,Hui Ma,Dingxi Liu,Wenliang Fan

doi:10.3389/fnins.2021.666651

Abstract

Sudden sensorineural hearing loss (SSNHL) is a sudden-onset hearing impairment that rapidly develops within 72 h and is mostly unilateral. Only a few patients can be identified with a defined cause by routine clinical examinations. Recently, some studies have shown that unilateral SSNHL is associated with alterations in the central nervous system. However, little is known about the topological organization of white matter (WM) networks in unilateral SSNHL patients in the acute phase. In this study, 145 patients with SSNHL and 91 age-, gender-, and education-matched healthy controls were evaluated using diffusion tensor imaging (DTI) and graph theoretical approaches. The topological properties of WM networks, including global and nodal parameters, were investigated. At the global level, SSNHL patients displayed decreased clustering coefficient, local efficiency, global efficiency, normalized clustering coefficient, normalized characteristic path length, and small-worldness and increased characteristic path length (p < 0.05) compared with healthy controls. At the nodal level, altered nodal centralities in brain regions involved the auditory network, visual network, attention network, default mode network (DMN), sensorimotor network, and subcortical network (p < 0.05, Bonferroni corrected). These findings indicate a shift of the WM network topology in SSNHL patients toward randomization, which is characterized by decreased global network integration and segregation and is reflected by decreased global connectivity and altered nodal centralities. This study could help us understand the potential pathophysiology of unilateral SSNHL.

Highlights

Sudden sensorineural hearing loss (SSNHL) is a sudden-onset and rapidly developed hearing impairment of at least 30 dB in no less than three contiguous frequencies within 72 h, which is a common emergency in ear-nose-throat clinics, along with tinnitus, vertigo, and so on (Stachler et al, 2012)
Due to its ambiguous etiology and pathogenesis, the majority of SSNHL cannot be determined with a defined cause for hearing loss by routine clinical examinations; these cases are considered as idiopathic SSNHL
The overall means of group global topological organization (λ, γ, σ, Cp, local efficiency (locE), global efficiency (gE), and Lp) are shown as a function of the threshold from n = 1∼5, where n represents the minimum number of white matter (WM) fibers needed to construct a connection between a pair of nodes

Summary

Introduction

Sudden sensorineural hearing loss (SSNHL) is a sudden-onset and rapidly developed hearing impairment of at least 30 dB in no less than three contiguous frequencies within 72 h, which is a common emergency in ear-nose-throat clinics, along with tinnitus, vertigo, and so on (Stachler et al, 2012). More than 95% of SSNHL cases are unilateral with no side of preference. Due to its ambiguous etiology and pathogenesis, the majority of SSNHL cannot be determined with a defined cause for hearing loss by routine clinical examinations; these cases are considered as idiopathic SSNHL. The main treatment for SSNHL is steroid therapy (Jung et al, 2016). The hearing function of patients with SSNHL shows little improvement even after suitable high-quality therapy, which may negatively affect economic indicators for the society and result in the poor long-term quality of their life (Manno et al, 2021)

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