Cortical Structure Abnormalities in Patients With Noise-Induced Hearing Loss: A Surface-Based Morphometry Study

To investigate the characteristics of brain structures in patients with noise-induced hearing loss (NIHL) using source-based morphometry (SBM) and to evaluate the correlation between abnormal brain regions and clinical data.

High-resolution 3D T1 structural images were acquired from 81 patients with NIHL and 74 age- and education level-matched healthy controls (HCs). The clinical data of all subjects were collected, including noise exposure time, monaural hearing threshold weighted values (MTWVs), Mini-Mental State Examination (MMSE), and Hamilton Anxiety Scale (HAMA) scores. The FreeSurfer software was used to perform whole-brain SBM analysis based on T1 images. The cortical morphological parameters included cortical thickness, surface area, and cortical volume. The correlations between abnormal cortical morphological changes in brain regions and noise exposure time, MTWV (superiority), and HAMA scores were further analyzed.

SBM results: NIHL patients had a greater cortical thickness in the left inferior parietal gyrus (IPG) and right superior parietal gyrus (SPG) compared with HCs (t = 2.916, p = 0.0474; t = 2.916, p = 0.0046); increased surface area and cortical volume were observed both in the left lateral occipital gyrus (LOG) in NIHL patients (t = 3.468, p = 0.0377; t = 3.091, p = 0.0002). Correlation analysis revealed that MTWV (superiority) was positively correlated with noise exposure time (r = 0.260, p = 0.019), and HAMA scores were negatively correlated with noise exposure time (r = -0.297, p = 0.007). Further, thicker cortical thickness in the left IPG and right SPG and increased cortical volume in the left LOG were negatively correlated with MTWV (superiority) (r = -0.238, p = 0.032; r = -0.255, p = 0.022; r = -0.272, p = 0.014). Increased cortical volume in the left LOG had a positive correlation with HAMA scores (r = 0.172, p = 0.032).

On the basis of the SBM method, we have discovered alterations in cortical morphology within the auditory-visual network regions such as the parietal and occipital lobes in NIHL patients. These findings suggest that auditory deprivation may initiate the restructuring of the auditory-visual cortex, providing new insights into the underlying mechanisms of brain activity abnormalities in NIHL patients. This study not only offers a new perspective on exploring brain structural anomalies associated with NIHL but also enhances our understanding of the neurobiology of NIHL.