Structural neuroimaging of the altered brain stemming from pediatric and adolescent hearing loss—Scientific and clinical challenges

Abstract

There has been a spurt in structural neuroimaging studies of the effect of hearing loss on the brain. Specifically, magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) technologies provide an opportunity to quantify changes in gray and white matter structures at the macroscopic scale. To date, there have been 32 MRI and 23 DTI studies that have analyzed structural differences accruing from pre-or peri-lingual pediatric hearing loss with congenital or early onset etiology and postlingual hearing loss in pre-to-late adolescence. Additionally, there have been 15 prospective clinical structural neuroimaging studies of children and adolescents being evaluated for cochlear implants. The results of the 70 studies are summarized in two figures and three tables. Plastic changes in the brain are seen to be multifocal rather than diffuse, that is, differences are consistent across regions implicated in the hearing, speech and language networks regardless of modes of communication and amplification. Structures in that play an important role in cognition are affected to a lesser extent. A limitation of these studies is the emphasis on volumetric measures and on homogeneous groups of subjects with hearing loss.It is suggested that additional measures of morphometry and connectivity could contribute to a greater understanding of the effect of hearing loss on the brain. Then an interpretation of the observed macroscopic structural differences is given. This is followed by discussion of how structural imaging can be combined with functional imaging to provide biomarkers for longitudinal tracking of amplification.

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

“…They found that determining the type of neural reorganization before cochlear implantation was valuable for predicting language outcomes. The benefit for predictive, deep learning algorithms to be trained with MRI and DTI data for clinical outcomes in hearing loss would be extremely valuable ( Ratnanather, 2020 ). Here we have created the prototypical endophenotype of hearing loss which could be used to mask ROI for these machine learning methods (See Data in Brief : for nii files).…”

“…Neuroimaging with MRI provides an accurate and reproducible assessment ( Nichols et al, 2017 ) for discerning the structural alterations of hearing loss ( Tarabichi et al, 2018 , Ratnanather, 2020 ). However, its diagnostic ability for hearing screening in children and adults has not yet been widely employed ( Feng et al, 2018 , Ropers et al, 2019 ).…”

“…However, its diagnostic ability for hearing screening in children and adults has not yet been widely employed ( Feng et al, 2018 , Ropers et al, 2019 ). One of the current drawbacks is the lack of a comprehensive assessment of the structural manifestations in hearing loss ( Tarabichi et al, 2018 , Simon et al, 2020 , Ratnanather, 2020 ). The limiting factors are the structural endophenotype of hearing loss is diverse and no consensus/consummate review has been developed or conducted.…”

“…cochlear) ( Moore et al, 1994 ) and onward to the primary auditory cortices (i.e. Heschl’s gyri), ( Tarabichi et al, 2018 , Ratnanather, 2020 ) where hearing loss is thought to affect gray matter (GM) ( Feng et al, 2018 ). Early onset hearing loss affects the central auditory system, ( Kral and O’Donoghue, 2010 , Kral et al, 2016 , Kral and Sharma, 2012 ) and later on in life, the cortical auditory processing areas are recruited by the visual system when they lose input (i.e.…”

“…What is the reorganization in WM and GM over critical developmental periods? The first structural studies of hearing loss ( Moore et al, 1994 , Moore et al, 1997 ) gave significant clues and current neuroimaging techniques with MRI ( Tarabichi et al, 2018 , Ratnanather, 2020 ) provide a unique ability to capture development periods, in order to answer these questions. Here we hope to bridge some of these limitations in the field by developing a consensus and structural endophenotype for acquired and congenital hearing loss.…”