Cortical imbalance following delayed restoration of bilateral hearing in deaf adolescents

Anderson, Carly A.; Cushing, Sharon L.; Papsin, Blake C.; Gordon, Karen A.

doi:10.1002/hbm.25875

Cited by 3 publications

(1 citation statement)

References 95 publications

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“…While restoration of binaural hearing can occur in listeners with long-standing hearing loss ( Firszt et al 2013 ; Távora‑Vieira et al 2013 ), hearing loss early in auditory development may be more detrimental than losses acquired later in development ( Kral et al 2015 ; Tillein et al 2016 ; Vanderauwera et al 2020 ). Younger age at implantation takes advantage of auditory neuroplasticity, which declines after 7 years of age ( Sharma et al 2002 ), and may avoid aural preference syndrome, which develops after years of unilateral input ( Sharma et al 2002 , 2016 ; Kral et al 2013 ; Tillein et al 2016 ; Polonenko et al 2017 , 2018 ; Lee et al 2020 ; Vanderauwera et al 2020 ; Anderson et al 2022 ).…”

Section: Discussionmentioning

confidence: 99%

Two-Year Outcomes of Cochlear Implant Use for Children With Unilateral Hearing Loss: Benefits and Comparison to Children With Normal Hearing

Park

Dillon²,

Buss³

et al. 2023

Ear &Amp; Hearing

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Objectives: Children with severe-to-profound unilateral hearing loss, including cases of single-sided deafness (SSD), lack access to binaural cues that support spatial hearing, such as recognizing speech in complex multisource environments and sound source localization. Listening in a monaural condition negatively impacts communication, learning, and quality of life for children with SSD. Cochlear implant (CI) use may restore binaural hearing abilities and improve outcomes as compared to alternative treatments or no treatment. This study investigated performance over 24 months of CI use in young children with SSD as compared to the better hearing ear alone and to children with bilateral normal hearing (NH). Design: Eighteen children with SSD who received a CI between the ages of 3.5 and 6.5 years as part of a prospective clinical trial completed assessments of word recognition in quiet, masked sentence recognition, and sound source localization at regular intervals out to 24-month postactivation. Eighteen peers with bilateral NH, matched by age at the group level, completed the same test battery. Performance at 24-month postactivation for the SSD group was compared to the performance of the NH group. Results: Children with SSD have significantly poorer speech recognition in quiet, masked sentence recognition, and localization both with and without the use of the CI than their peers with NH. The SSD group experienced significant benefits with the CI+NH versus the NH ear alone on measures of isolated word recognition, masked sentence recognition, and localization. These benefits were realized within the first 3 months of use and were maintained through the 24-month postactivation interval. Conclusions: Young children with SSD who use a CI experience significant isolated word recognition and bilateral spatial hearing benefits, although their performance remains poorer than their peers with NH.

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Section: Discussionmentioning

confidence: 99%

Two-Year Outcomes of Cochlear Implant Use for Children With Unilateral Hearing Loss: Benefits and Comparison to Children With Normal Hearing

Park

Dillon²,

Buss³

et al. 2023

Ear &Amp; Hearing

View full text Add to dashboard Cite

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Cortical imbalance following delayed restoration of bilateral hearing in deaf adolescents

Anderson

Cushing

Papsin

et al. 2022

Human Brain Mapping

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Unilateral auditory deprivation in early childhood can lead to cortical strengthening of inputs from the stimulated side, yet the impact of this on bilateral processing when inputs are later restored beyond an early sensitive period is unknown. To address this, we conducted a longitudinal study with 13 bilaterally profoundly deaf adolescents who received unilateral access to sound via a cochlear implant (CI) in their right ear in early childhood before receiving bilateral access to sound a decade later via a second CI in their left ear. Auditory-evoked cortical responses to unilateral and bilateral stimulation were measured repeatedly using electroencephalogram from 1 week to 14 months after activation of their second CI. Early cortical responses from the newly implanted ear and bilateral stimulation were atypically lateralized to the left ipsilateral auditory cortex. Duration of unilateral deafness predicted an unexpectedly stronger representation of inputs from the newly implanted, compared to the first implanted ear, in left auditory cortex. Significant initial reductions in responses were observed, yet a left-hemisphere bias and unequal weighting of inputs favoring the long-term deaf ear did not converge to a balanced state observed in the binaurally developed system. Bilateral response enhancement was significantly reduced in left auditory cortex suggesting deficits in ipsilateral response inhibition of new, dominant, inputs during bilateral processing. These findings paradoxically demonstrate the adaptive capacity of the adolescent auditory system beyond an early sensitive period for bilateral input, as well as restrictions on its potential to fully reverse cortical imbalances driven by long-term unilateral deafness.

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Dissociated Representation of Binaural Cues in Single-Sided Deafness: Implications for Cochlear Implantation

Hubka,

Schmidt,

Tillein

et al. 2024

J. Neurosci.

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Congenital single-sided deafness (SSD) leads to an aural preference syndrome that is characterized by overrepresentation of the hearing ear in the auditory system. Cochlear implantation (CI) of the deaf ear is an effective treatment for SSD. However, the newly introduced auditory input in congenital SSD often does not reach expectations in late-implanted CI recipients with respect to binaural hearing and speech perception. In a previous study, a reduction of interaural time difference (ITD) sensitivity has been shown in unilaterally congenitally deaf cats (uCDC). In the present study, we focused on the interaural level difference (ILD) processing in the primary auditory cortex. The uCDC group was compared with hearing cats (HC) and bilaterally congenitally deaf cats (CDC). The ILD representation was reorganized, replacing the preference for the contralateral ear with a preference for the hearing ear, regardless of the cortical hemisphere. In accordance with the previous study, uCDCs were less sensitive to interaural time differences than HCs, resulting in unmodulated ITD responses, thus lacking directional information. Such incongruent ITDs and ILDs cannot be integrated for binaural sound source localization. In normal hearing the predominant effect of each ear is excitation of auditory cortex in the contralateral cortical hemisphere and inhibition in the ipsilateral hemisphere. In SSD, however, auditory pathways reorganized such that the hearing ear produced greater excitation in both cortical hemispheres and the deaf ear produced weaker excitation and preserved inhibition in both cortical hemispheres.Significance statementCongenital single-sided deafness is a clinically relevant form of hearing loss. We studied this phenomenon in a unique animal model with congenital deafness of one ear and normal hearing of the other ear with electrical stimulation on both ears. Differential effects of single-sided deafness on interaural time and level difference sensitivity were observed, consistent with the aural preference syndrome. The influence of the previously hearing ear became dominant and the deaf ear mildly suppressive in the majority of units in both hemispheres, resulting in an inconsistent representation of binaural cues. These changes in neuronal representation of the two ears explain why late restoration with cochlear implants in single-sided deafness often results in insufficient benefit of the previously deaf ear.

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Cortical imbalance following delayed restoration of bilateral hearing in deaf adolescents

Cited by 3 publications

References 95 publications

Two-Year Outcomes of Cochlear Implant Use for Children With Unilateral Hearing Loss: Benefits and Comparison to Children With Normal Hearing

Two-Year Outcomes of Cochlear Implant Use for Children With Unilateral Hearing Loss: Benefits and Comparison to Children With Normal Hearing

Cortical imbalance following delayed restoration of bilateral hearing in deaf adolescents

Dissociated Representation of Binaural Cues in Single-Sided Deafness: Implications for Cochlear Implantation

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