Consistent and chronic cochlear implant use partially reverses cortical effects of single sided deafness in children

Abstract

Potentially neuroprotective effects of CI use were studied in 22 children with single sided deafness (SSD). Auditory-evoked EEG confirmed strengthened representation of the intact ear in the ipsilateral auditory cortex at initial CI activation in children with early-onset SSD (n = 15) and late-onset SSD occurring suddenly in later childhood/adolescence (n = 7). In early-onset SSD, representation of the hearing ear decreased with chronic CI experience and expected lateralization to the contralateral auditory cortex from the CI increased with longer daily CI use. In late-onset SSD, abnormally high activity from the intact ear in the ipsilateral cortex reduced, but responses from the deaf ear weakened despite CI use. Results suggest that: (1) cortical reorganization driven by unilateral hearing can occur throughout childhood; (2) chronic and consistent CI use can partially reverse these effects; and (3) CI use may not protect children with late-onset SSD from ongoing deterioration of pathways from the deaf ear.

Proficiency in Using Level Cue for Sound Localization Is Related to the Auditory Cortical Structure in Patients With Single-Sided Deafness

“…Compared to bilateral deafness, SSD is a more recent focus of dedicated research, and less is known about neuroplasticity following unilateral hearing loss ( Vanderauwera et al, 2020 ). Although the overall number of studies is small and the audiologic profiles included are diverse, neural changes associated with asymmetric hearing have been observed in both functional and structural domains and are related to clinical/audiologic variables such as the duration of SSD ( Yang et al, 2014 ; Wang et al, 2016 ), age at SSD onset ( Lee et al, 2020 ), severity of hearing impairment ( Wang et al, 2016 ; Xie et al, 2019 ), and side ( Khosla et al, 2003 ; Burton et al, 2012 ; Zhang et al, 2016 ; Heggdal et al, 2019 ; Xie et al, 2019 ; Han et al, 2021 ). However, findings are scarce regarding how the observed neuroplasticity in asymmetric hearing is related to binaural auditory performance, such as sound localization ability.…”

Functional Consequences of Poor Binaural Hearing in Development: Evidence From Children With Unilateral Hearing Loss and Children Receiving Bilateral Cochlear Implants

“…This means that they have normal hearing sensitivity from their hearing ear but no access to binaural cues ( Avan et al, 2015 ; Kumpik & King, 2019 ), impairing sound localization ( Bess & Tharpe, 1984 ; Reeder et al, 2015 ) and speech understanding in noise ( Lieu, 2004 ; Lieu et al, 2012 ; Noh & Park, 2012 ; Ruscetta et al, 2005 ). Early results of cochlear implantation in children with profound unilateral hearing loss of limited duration suggest potential benefits ( Deep et al, 2021 ; Lee et al, 2020 ), but this treatment is not standard of care in all countries.…”

Brain plasticity and hearing disorders

“…In the most severe cases of single-sided deafness (SSD), a cochlear implant provides the highest quality of life and higher behavioral performances, such as localization and speech recognition in noise [64,83]. Cortical activity recovery after SSD rehabilitation was shown for the moment only with EEG within a pediatric SSD population [62,84]. These two studies provide some evidence that CI devices could partially restore cortical sound treatment asymmetry approaching NH listeners.…”

“…Therefore, subjects, either children or adults, experiencing asymmetrical hearing loss present deleterious behavioral consequences [57][58][59]. For example, in children, profound unilateral hearing loss stirs developmental [60] and language [58] delays inducing lower school performances (higher grade failure up to 33% [58,61], thus requiring intervention as early as possible to avoid future handicaps in their daily life [62,63]. In UHL adults compared to NH peers, consequences are presented as degraded localization and speech recognition-in-noise performances [64,65] and a lower global quality of life [66].…”

“…These two studies provide some evidence that CI devices could partially restore cortical sound treatment asymmetry approaching NH listeners. However, the onset of SSD (early or late) might be crucial for brain plasticity [62]. In early-onset SSD children (0-5 years of age), sound stimulation through CI creates an asymmetrical cortical sound representation in the contralateral hemisphere whereas in late-onset SSD children (10-16 years of age) even with the same implant duration as the earlyonset group (one year on average), sound representation is more symmetrical in both hemispheres probably because children still strongly rely on the better ear.…”