Anatomical and Functional MRI Changes after One Year of Auditory Rehabilitation with Hearing Aids

Abstract

Hearing aids (HAs) are an effective strategy for auditory rehabilitation in patients with peripheral hearing deficits. Yet, the neurophysiological mechanisms behind HA use are still unclear. Thus far, most studies have focused on changes in the auditory system, although it is expected that hearing deficits affect a number of cognitive systems, notably speech. In the present study, we used audiometric evaluations in 14 patients with bilateral hearing loss before and after one year of continuous HA use and functional magnetic resonance imaging (fMRI) and cortical thickness analysis in 12 and 10 of them compared with a normal hearing control group. Prior to HA fitting, fMRI activity was found reduced in the auditory and language systems and increased in visual and frontal areas, expanding to multimodal integration cortices, such as the superior temporal gyrus, intraparietal sulcus, and insula. One year after rehabilitation with HA, significant audiometric improvement was observed, especially in free-field Speech Reception Threshold (SRT) test and functional gain, a measure of HA efficiency. HA use increased fMRI activity in the auditory and language cortices and multimodal integration areas. Individual fMRI signal changes from all these areas were positively correlated with individual SRT changes. Before rehabilitation, cortical thickness was increased in parts of the prefrontal cortex, precuneus, fusiform gyrus, and middle temporal gyrus. It was reduced in the insula, supramarginal gyrus, medial temporal gyrus, occipital cortex, posterior cingulate cortex, and claustrum. After HA use, increased cortical thickness was observed in multimodal integration regions, particularly the very caudal end of the superior temporal sulcus, the angular gyrus, and the inferior parietal gyrus/superior temporal gyrus/insula. Our data provide the first evidence that one year of HA use is related to functional and anatomical brain changes, notably in auditory and language systems, extending to multimodal cortices.

Cortical reorganization following auditory deprivation predicts cochlear implant performance in postlingually deaf adults

“…Functional imaging studies show that the degree of neural activity in the occipital cortex in response to a visual stimulus is associated with deafness duration (Shiell, Champoux, & Zatorre, 2015) and post‐CI outcome (Green et al, 2005; Sandmann et al, 2012; Strelnikov et al, 2013; Stropahl et al, 2017). However, we observed no structural changes in the visual cortex in the PD group in relation either to deafness progression or post‐CI outcome, which is in accordance with other structural MRI studies (Peelle et al, 2011; Pereira‐Jorge et al, 2018). This lack of a relationship between structure changes in the visual cortex and post‐CI outcome needs further clarification but indicates that the neural activity in the original visual processing site may not exceed the normal range, thus inducing no structural alteration of the visual cortex in the context of cortical reorganization.…”

Brain Structural and Functional Reorganization in Tinnitus Patients Without Hearing Loss After Sound Therapy: A Preliminary Longitudinal Study

“…The temporal gyrus is closely related to auditory function, especially the posterior MTG, which is part of the auditory primary cortex. Studies have shown that tinnitus can cause significant cortical changes in the MTG ( Boyen et al, 2013 ; Pereira-Jorge et al, 2018 ). For example, Boyen et al (2013) found that the change in gray matter in the auditory primary cortex (including the MTG) was correlated with tinnitus rather than with HL, and they speculated that the continuous sensation of an internal sound, such as the tinnitus percept, may cause the changes in the MTG.…”

Hearing loss impacts gray and white matter across the lifespan: Systematic review, meta-analysis and meta-regression

“…Postlingual, or late onset, hearing loss is often a comorbidity with tinnitus ( Boyen et al, 2013 , Luan et al, 2019 , Husain et al, 2011 ). General presbycusis ( Peelle et al, 2011 , Lin et al, 2014 , Rigters et al, 2017 , Rigters et al, 2018 ) - acquired hearing loss due to aging - is often comorbid with dementia ( Cunningham and Tucci, 2017 , Reed et al, 2019 , Lin, 2013 ) and confounded by hearing aid use ( Pereira-Jorge et al, 2018 ). Half the people in their 7 th decade or older have hearing loss, which affects communication ( Olkin et al, 2012 ).…”