Deprivation-induced cortical reorganization in children with cochlear implants

Bidirectional remodeling of the central auditory system caused by unilateral auditory deprivation

Unilateral auditory deprivation (UAD) results in cross-modal reorganization of the auditory cortex (AC), which can impair auditory and cognitive functions and diminish the recovery effect of cochlear implantation. Moreover, the subcortical areas provide extensive ascending projections to the AC. To date, a thorough systematic study of subcortical auditory neural plasticity has not been undertaken. Therefore, this review aims to summarize the current evidence on the bidirectional remodeling of the central auditory system caused by UAD, particularly the changes in subcortical neural plasticity. Lateral changes occur in the cochlear nucleus, lateral superior olive, medial nucleus of the trapezoid body, inferior colliculus, and AC of individuals with UAD. Moreover, asymmetric neural activity becomes less prominent in the higher auditory nuclei, which may be due to cross-projection regulation of the bilateral pathway. As a result, subcortical auditory neural plasticity caused by UAD may contribute to the outcomes of cochlear implantation in patients with single-sided deafness (SSD), and the development of intervention strategies for patients with SSD is crucial. Considering that previous studies have focused predominantly on the neural plasticity of the AC, we believe that bidirectional remodeling of subcortical areas after UAD is also crucial for investigating the mechanisms of interventions.

Neurocognitive outcomes in young adults with cochlear implants: The role of early language access and crossmodal plasticity

Many children with profound hearing loss have received cochlear implants (CI) to help restore some sense of hearing. There is, however, limited research on long-term neurocognitive outcomes in young adults who have grown up hearing through a CI. This study compared the cognitive outcomes of early-implanted (n = 20) and late-implanted (n = 21) young adult CI users, and typically hearing (TH) controls (n=56), all of whom were enrolled in college. Cognitive fluidity, nonverbal intelligence, and American Sign Language (ASL) comprehension were assessed, revealing no significant differences in cognition and nonverbal intelligence between the early and late-implanted groups. However, there was a difference in ASL comprehension, with the late-implanted group having significantly higher ASL comprehension. Although young adult CI users showed significantly lower scores in a working memory and processing speed task than TH age-matched controls, there were no significant differences in tasks involving executive function shifting, inhibitory control, and episodic memory between young adult CI and young adult TH participants. In an exploratory analysis of a subset of CI participants (n = 17) in whom we were able to examine crossmodal plasticity, we saw greater evidence of crossmodal recruitment from the visual system in late-implanted compared with early-implanted CI young adults. However, cortical visual evoked potential latency biomarkers of crossmodal plasticity were not correlated with cognitive measures or ASL comprehension. The results suggest that in the late-implanted CI users, early access to sign language may have served as a scaffold for appropriate cognitive development, while in the early-implanted group early access to oral language benefited cognitive development. Furthermore, our results suggest that the persistence of crossmodal neuroplasticity into adulthood does not necessarily impact cognitive development. In conclusion, early access to language - spoken or signed - may be important for cognitive development, with no observable effect of crossmodal plasticity on cognitive outcomes.

Central Auditory Changes Associated with Age-related Hearing Loss

Objective. This study aimed to investigate age-related changes in cortical auditory evoked potentials (CAEPs) while considering three crucial factors: aging, high-frequency hearing loss and sensation level of the CAEP stimulus. Method. The electrophysiological and audiometric data of 71 elderly participants were analyzed using multiple regression analysis to investigate the association of CAEPs with the factors of aging, high-frequency hearing loss and sensation level of the CAEP test stimulus. Results. Aging was significantly associated with prolonged N1 and P2 latencies and reduced P2 amplitude. Elevated thresholds related to the sensation level of the CAEP stimulus were significantly associated with increased N1 and P2 amplitudes and decreased N1 latency. A significant relationship was detected between high-frequency hearing thresholds and the shortening of P2 latencies and the reduction of P2 amplitudes. Conclusion. The results of this study highlight the complex interplay of aging, high-frequency hearing loss and the sensation level of the CAEP stimulus on CAEP components in elderly people. These factors should be considered in future research using CAEPs to enhance overall understanding of auditory processing in the aging population.

Cross-modal plasticity in children with cochlear implant: converging evidence from EEG and functional near-infrared spectroscopy

Over the first years of life, the brain undergoes substantial organization in response to environmental stimulation. In a silent world, it may promote vision by (i) recruiting resources from the auditory cortex and (ii) making the visual cortex more efficient. It is unclear when such changes occur and how adaptive they are, questions that children with cochlear implants can help address. Here, we examined 7-18 years old children: 50 had cochlear implants, with delayed or age-appropriate language abilities, and 25 had typical hearing and language. High-density electroencephalography and functional near-infrared spectroscopy were used to evaluate cortical responses to a low-level visual task. Evidence for a 'weaker visual cortex response' and 'less synchronized or less inhibitory activity of auditory association areas' in the implanted children with language delays suggests that cross-modal reorganization can be maladaptive and does not necessarily strengthen the dominant visual sense.

Auditory Cortex Maturation and Language Development in Children with Hearing Loss and Additional Disabilities

A significant portion of hearing-impaired children have additional disabilities, but data about the maturation of their auditory cortex are scarce. In these children, behavioral tests are often unreliable, and objective tests are needed for diagnostics and follow-up. This study aimed to explore auditory cortical maturation and language development, and the usability of an objective electroencephalogram-based biomarker in children with multiple disabilities. In 65 hearing aid and cochlear implant users (36 females; 36 with multiple disabilities; 44.3 ± 18.5 months of age, mean ± SD), auditory processing was examined using the P1 cortical auditory evoked response biomarker, and language development with the Preschool Language Scales 5th edition (PLS-5). During the study, all of the children received intensive extra language therapy for six months. No significant differences were found between the groups in P1 latency development, the proportion of abnormal P1 latencies, or the number of children whose P1 latencies changed from abnormal to normal during the study. The PLS-5 total language scores, auditory comprehension scores, or expressive communication scores did not differ between groups either. The P1 latencies showed meaningful negative correlations with the language scores. The results suggest that auditory cortex development is similar in hearing-impaired children with/without additional disabilities, and the P1 biomarker is a feasible tool to evaluate central auditory maturation in children with multiple disabilities.

Cortical auditory evoked potentials (P1 latency) in children with cochlear implants in relation to clinical language tests

Objective - To study the correlation between P1 latency and the results of clinical language tests (Reynell III and TROG-2), the latter were used as they are recommended for follow-up assessments of children with cochlear implants (Cis) by the Swedish National Quality Register for children with hearing impairment.Design - A clinical cohort study.Study sample - Cross-sectional and consecutive sampling of 49 children with CIs coming for clinical follow-up assessment from March 2017 - December 2019.Results - For all children tested, there was a significant negative correlation (Spearman's rho= -0.403, p = 0.011) between hearing age and P1 latency. A significant correlation between P1 latency and the Reynell III result (Spearman's rho =  -0.810, p = 0.015) was found. In the TROG-2 group, there was no significant correlation between their P1 latency and their language test results (Spearman's rho -0.239, p = 0.196).Conclusion - This method seems to be feasible and easily accepted. The study was conducted in a heterogeneous group of children that we meet daily in our clinic. The results indicated that P1 latency has a negative correlation with language development among our youngest patients fitted with CIs and might be a clinical tool to assess the maturation of central auditory pathways.

Evaluation of Verbal Working Memory and Phonemic Analysis Skills in Adolescents with Cochlear Implant

Introduction  Adolescents with cochlear implants may have difficulty developing language and memory abilities. Objective  The primary objectives of this study are (1) to evaluate the language skills and verbal working memory performance of early and late diagnosed-intervened cochlear implanted adolescents and (2) to investigate the relationship between the verbal working memory and phonemic analysis skills in adolescents with cochlear implant. Methods  This study included 72 participants with cochlear implant aged between 10 and 18 years. The participants were divided into two groups; those who had first hearing aid at the age of 6 months at the latest and had a first cochlear implant in at least one ear at the latest at 24 months were included in the early group, all the others were in the late group. The phonemic analysis test, a subtest of the test of language development: Primary, 4th edition (TOLD: P-4) - Turkish version, was used to assess language-based abilities, and the meaningless word repetition (MWR) test was utilized to assess verbal working memory. Results  The adolescents with cochlear implants who received early diagnosis and intervention performed statistically significantly better in phonemic analysis scores and verbal working memory tests ( p  < 0.001). A statistically significant relationship was found between phonemic analysis and verbal working memory skills (Pearson, r = 0.567 and r = 0.659, p  < 0.001). Conclusions  Rehabilitation of phonological skills can contribute to the development of verbal working memory in adolescents with cochlear implants. There is a need for further studies on this issue with more detailed tests.

An association between auditory responsiveness of children and duration of entertainment screen time in the early years of life

OBJECTIVE

To examine whether the responsiveness of young children to simple sounds was associated with entertainment screen time (EST), opportunities for social interaction, and social and communication skills.

DESIGN

Parents completed a questionnaire covering, for years one and two, the number of times the child met with other children; the number of words the child spoke; and the daily amount of EST. Social, attention and communication skills were assessed.

STUDY SAMPLE

Participants were 118 children, aged 15 to 46 months. They were initially assessed behaviourally using simple sounds. Children who responded to such sounds were denoted the Responsive group. Children who did not were assessed using familiar songs and denoted the Unresponsive group.

RESULTS

The two groups did not differ significantly in mean age or the number of opportunities to meet other children. The Unresponsive group had significantly fewer words than the Responsive group at 12 and 24 months and had significantly higher EST than the Responsive group for years 1 and 2. The Unresponsive group showed lower social, attention and communication skills than the Responsive group.

CONCLUSIONS

High EST was associated with poorer auditory and social skills. Hence, it may be wise to limit the EST of young children.

Parental insights on Hearing Aid Usage in the ear Contralateral to unilateral Cochlear Implant among Children

AIM & OBJECTIVES

The aim of the present study was in three-fold: (a) to analyze the factors that affect the hearing aid (HA) continuation/discontinuation in children with unilateral cochlear implant (CI); (b) to understand the parent's knowledge on binaural benefit; and (c) to find out any association between the hearing aid continuation/discontinuation with implant age and/or with duration of hearing aid use prior to surgery.

METHOD

The study involved 97 participants who were parents of children with unilateral cochlear implants. A questionnaire with 30 questions was used to explore HA use and certain related perceptions, and a Likert scale was used for ranking responses.

RESULTS

& Discussion: Only 31.9% children were using HA consistently, post CI activation The principal factor for discontinuation of HA was its helpfulness prior CI whereas children wore HA only because they were instructed during counseling. Participants did not perceive functional benefit bimodal fitting due to superiority of CI performance and poor residual hearing. Also, it was found that there is no association between neither the implant age nor duration of HA use before CI with the HA continuation/discontinuation on Chi-square test.

CONCLUSIONS

The results suggest a need for structured comprehensive counseling and demonstration sessions to educate parents on binaural hearing to gain maximum benefits from non-invasive bimodal fitting.

Long-term speech perception performance in prelingually deafened adult cochlear implant recipients

To investigate the postoperative long-term outcomes after an average of 9.2 years following cochlear implantation (CI) in prelingually deafened adults, along with preimplantation factors predicting postoperative outcomes.

Twenty-six prelingually deafened adults who underwent CI at >18 years were compared with those who had undergone CI in childhood (<9 years) and were >10 years old. Outcome measures includedhearing thresholds, preoperative and postoperative aided hearing level (HL), speech discrimination score (SDS), and Categories of Auditory Performance (CAP) scores. Correlation analyses were performed on the following: SDS results, aided HL, school attendant status, implant manufacturers, and speech processor models.

Improvement was achieved in the aided HL and SDS results, although these results were not better than those of the child group. CAP score was also statistically significantly improved after CI. Statistically significant correlation between the preoperative SDS and postoperative HL with CI results was observed. In other words, the better the preoperative SDS results, the better the postoperative SDS results.

Prelingually deafened adults achieved considerable improvement through CI. It is important to understand that patients achieving better hearing with a well-fitted hearing aid and good SDS performance before surgery may be good candidates for CI.

Dynamic networks differentiate the language ability of children with cochlear implants

Background

Cochlear implantation (CI) in prelingually deafened children has been shown to be an effective intervention for developing language and reading skill. However, there is a substantial proportion of the children receiving CI who struggle with language and reading. The current study-one of the first to implement electrical source imaging in CI population was designed to identify the neural underpinnings in two groups of CI children with good and poor language and reading skill.

Methods

Data using high density electroencephalography (EEG) under a resting state condition was obtained from 75 children, 50 with CIs having good (HL) or poor language skills (LL) and 25 normal hearing (NH) children. We identified coherent sources using dynamic imaging of coherent sources (DICS) and their effective connectivity computing time-frequency causality estimation based on temporal partial directed coherence (TPDC) in the two CI groups compared to a cohort of age and gender matched NH children.

Findings

Sources with higher coherence amplitude were observed in three frequency bands (alpha, beta and gamma) for the CI groups when compared to normal hearing children. The two groups of CI children with good (HL) and poor (LL) language ability exhibited not only different cortical and subcortical source profiles but also distinct effective connectivity between them. Additionally, a support vector machine (SVM) algorithm using these sources and their connectivity patterns for each CI group across the three frequency bands was able to predict the language and reading scores with high accuracy.

Interpretation

Increased coherence in the CI groups suggest overall that the oscillatory activity in some brain areas become more strongly coupled compared to the NH group. Moreover, the different sources and their connectivity patterns and their association to language and reading skill in both groups, suggest a compensatory adaptation that either facilitated or impeded language and reading development. The neural differences in the two groups of CI children may reflect potential biomarkers for predicting outcome success in CI children.

Somatosensory gating is related to behavioral and verbal outcomes in children with mild-to-severe hearing loss

Sensory gating is a process by which the brain filters out redundant information to preserve neural resources for behaviorally relevant stimuli. Although studies have shown alterations in auditory and visual processing in children who are hard-of-hearing (CHH) relative to children with normal hearing (CNH), it is unclear whether these alterations extend to the somatosensory domain, and how aberrations in sensory processing affect sensory gating. In this study, CHH and CNH were presented with a paired-pulse median nerve stimulation during magnetoencephalography. Stimulus-related gamma neural activity was imaged and virtual time series from peak somatosensory responses were extracted. We found significant effects of both stimulus and group, as well as a significant group-by-stimulus interaction. CHH showed a larger response to stimulation overall, as well as greater differences in gamma power from the first to the second stimulus. However, when looking at the ratio rather than the absolute difference in power, CHH showed comparable gating to CNH. In addition, smaller gating ratios were correlated with better classroom behavior and verbal ability in CHH, but not CNH. Taken together, these data underscore the importance of considering how CHH experience their multisensory environment when interpreting outcomes and designing interventions.

Cochlear Implantation: Systematic Approach to Preoperative Radiologic Evaluation

Sensorineural hearing loss results from abnormalities that affect the hair cells of the membranous labyrinth, inner ear malformations, and conditions affecting the auditory pathway from the cochlear nerve to the processing centers of the brain. Cochlear implantation is increasingly being performed for hearing rehabilitation owing to expanding indications and a growing number of children and adults with sensorineural hearing loss. An adequate understanding of the temporal bone anatomy and diseases that affect the inner ear is paramount for alerting the operating surgeon about variants and imaging findings that can influence the surgical technique, affect the choice of cochlear implant and electrode type, and help avoid inadvertent complications. In this article, imaging protocols for sensorineural hearing loss and the normal inner ear anatomy are reviewed, with a brief description of cochlear implant devices and surgical techniques. In addition, congenital inner ear malformations and acquired causes of sensorineural hearing loss are discussed, with a focus on imaging findings that may affect surgical planning and outcomes. The anatomic factors and variations that are associated with surgical challenges and may predispose patients to periprocedural complications also are highlighted. ^© RSNA, 2023 Quiz questions for this article are available through the Online Learning Center. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Acoustic change complex for assessing speech discrimination in normal-hearing and hearing-impaired infants

OBJECTIVE

This study examined (1) the utility of a clinical system to record acoustic change complex (ACC, an event-related potential recorded by electroencephalography) for assessing speech discrimination in infants, and (2) the relationship between ACC and functional performance in real life.

METHODS

Participants included 115 infants (43 normal-hearing, 72 hearing-impaired), aged 3-12 months. ACCs were recorded using [szs], [uiu], and a spectral rippled noise high-pass filtered at 2 kHz as stimuli. Assessments were conducted at age 3-6 months and at 7-12 months. Functional performance was evaluated using a parent-report questionnaire, and correlations with ACC were examined.

RESULTS

The rates of onset and ACC responses of normal-hearing infants were not significantly different from those of aided infants with mild or moderate hearing loss but were significantly higher than those with severe loss. On average, response rates measured at 3-6 months were not significantly different from those at 7-12 months. Higher rates of ACC responses were significantly associated with better functional performance.

CONCLUSIONS

ACCs demonstrated auditory capacity for discrimination in infants by 3-6 months. This capacity was positively related to real-life functional performance.

SIGNIFICANCE

ACCs can be used to evaluate the effectiveness of amplification and monitor development in aided hearing-impaired infants.

Complications and outcomes of cochlear implantation in children younger than 12 months: A multicenter study

OBJECTIVES

Evidence suggests that Cochlear Implantation (CI) is a beneficial approach for auditory and speech skills improvement in children with severe to profound hearing loss. However, it remains controversial if implantation in children <12 months is safe and effective compared to older children. The present study aimed to determine whether children's ages affect surgical complications and auditory and speech development.

METHODS

The current multicenter study enrolled 86 children who underwent CI surgery at <12 months of age (group A) and 362 children who underwent implantation between 12 and 24 months of age (group B). The Categories of Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) scores were determined pre-impanation, and "one-year" and "two-year" post-implantation.

RESULTS

All children had full insertions of the electrode array. Four complications (overall rate: 4.65%; three minor) occurred in group A and 12 complications (overall rate: 4.41%; nine minor) occurred in group B. We found no statistically significant difference in the complication rates between the groups (p > 0.05). The mean SIR and CAP scores improved over time following CI activation in both groups. However, we did not find significant differences in CAP and SIR scores between the groups across different time points.

CONCLUSION

Cochlear implantation in children younger than 12 months is a safe and efficient procedure, providing substantial auditory and speech benefits. Furthermore, rates and nature of minor and major complications in infants are similar to those of children undergoing the CI at an older age.

Cochlear implants: Visual evoked potentials study

Cochlear implants (CIs) are a successful alternative in cases with severe-to-profound HL. In these individuals, visual cross-modal re-organization can occur because of hearing loss where the visual cortex will recruit auditory cortical areas for visual processing.

OBJECTIVES

This work is designed to study visual evoked potentials (VEPs) in children fitted with CIs in comparison to normal hearing children.

METHOD

This work included 2 groups of children: Group I included 20 normal hearing children and study group included 25 children fitted with unilateral CIs. All cases were subjected to Thorough otological history. Check up on CIs performance using physical check and Aided sound field examination, ophthalmic examination and Pattern Visual Evoked Potentials (pVEPs).

RESULTS

Both groups showed no significant difference as regard age or sex. And both had normal ophthalmic examinations. Children of the study groups showed satisfactory aided response. As regard pVEPs, the study group showed significant higher P100 amplitude in comparison to the control group.

CONCLUSION

This study showed that deafness could induced cortical organization in the visual cortex and not limited to the auditory cortex only.

Image-Guided Cochlear Implant Programming: A Systematic Review and Meta-analysis

OBJECTIVE

To review studies evaluating clinically implemented image-guided cochlear implant programing (IGCIP) and to determine its effect on cochlear implant (CI) performance.

DATA SOURCES

PubMed, EMBASE, and Google Scholar were searched for English language publications from inception to August 1, 2021.

STUDY SELECTION

Included studies prospectively compared intraindividual CI performance between an image-guided experimental map and a patient's preferred traditional map. Non-English studies, cadaveric studies, and studies where imaging did not directly inform programming were excluded.

DATA EXTRACTION

Seven studies were identified for review, and five reported comparable components of audiological testing and follow-up times appropriate for meta-analysis. Demographic, speech, spectral modulation, pitch accuracy, and quality-of-life survey data were collected. Aggregate data were used when individual data were unavailable.

DATA SYNTHESIS

Audiological test outcomes were evaluated as standardized mean change (95% confidence interval) using random-effects meta-analysis with raw score standardization. Improvements in speech and quality-of-life measures using the IGCIP map demonstrated nominal effect sizes: consonant-nucleus-consonant words, 0.15 (-0.12 to 0.42); AzBio quiet, 0.09 (-0.05 to 0.22); AzBio +10 dB signal-noise ratio, 0.14 (-0.01 to 0.30); Bamford-Kowel-Bench sentence in noise, -0.11 (-0.35 to 0.12); Abbreviated Profile of Hearing Aid Benefit, -0.14 (-0.28 to 0.00); and Speech Spatial and Qualities of Hearing Scale, 0.13 (-0.02 to 0.28). Nevertheless, 79% of patients allowed to keep their IGCIP map opted for continued use after the investigational period.

CONCLUSION

IGCIP has potential to precisely guide CI programming. Nominal effect sizes for objective outcome measures fail to reflect subjective benefits fully given discordance with the percentage of patients who prefer to maintain their IGCIP map.

The Effects of Cortical Reorganization and Applications of Functional Near-Infrared Spectroscopy in Deaf People and Cochlear Implant Users

A cochlear implant (CI) is currently the only FDA-approved biomedical device that can restore hearing for the majority of patients with severe-to-profound sensorineural hearing loss (SNHL). While prelingually and postlingually deaf individuals benefit substantially from CI, the outcomes after implantation vary greatly. Numerous studies have attempted to study the variables that affect CI outcomes, including the personal characteristics of CI candidates, environmental variables, and device-related variables. Up to 80% of the results remained unexplainable because all these variables could only roughly predict auditory performance with a CI. Brain structure/function differences after hearing deprivation, that is, cortical reorganization, has gradually attracted the attention of neuroscientists. The cross-modal reorganization in the auditory cortex following deafness is thought to be a key factor in the success of CI. In recent years, the adaptive and maladaptive effects of this reorganization on CI rehabilitation have been argued because the neural mechanisms of how this reorganization impacts CI learning and rehabilitation have not been revealed. Due to the lack of brain processes describing how this plasticity affects CI learning and rehabilitation, the adaptive and deleterious consequences of this reorganization on CI outcomes have recently been the subject of debate. This review describes the evidence for different roles of cross-modal reorganization in CI performance and attempts to explore the possible reasons. Additionally, understanding the core influencing mechanism requires taking into account the cortical changes from deafness to hearing restoration. However, methodological issues have restricted longitudinal research on cortical function in CI. Functional near-infrared spectroscopy (fNIRS) has been increasingly used for the study of brain function and language assessment in CI because of its unique advantages, which are considered to have great potential. Here, we review studies on auditory cortex reorganization in deaf patients and CI recipients, and then we try to illustrate the feasibility of fNIRS as a neuroimaging tool in predicting and assessing speech performance in CI recipients. Here, we review research on the cross-modal reorganization of the auditory cortex in deaf patients and CI recipients and seek to demonstrate the viability of using fNIRS as a neuroimaging technique to predict and evaluate speech function in CI recipients.

Contralateral dominance to speech in the adult auditory cortex immediately after cochlear implantation

Sensory deprivation causes structural and functional changes in the human brain. Cochlear implantation delivers immediate reintroduction of auditory sensory information. Previous reports have indicated that over a year is required for the brain to reestablish canonical cortical processing patterns after the reintroduction of auditory stimulation. We utilized functional near-infrared spectroscopy (fNIRS) to investigate brain activity to natural speech stimuli directly after cochlear implantation. We presented 12 cochlear implant recipients, who each had a minimum of 12 months of auditory deprivation, with unilateral auditory- and visual-speech stimuli. Regardless of the side of implantation, canonical responses were elicited primarily on the contralateral side of stimulation as early as 1 h after device activation. These data indicate that auditory pathway connections are sustained during periods of sensory deprivation in adults, and that typical cortical lateralization is observed immediately following the reintroduction of auditory sensory input.

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Auditory activity was present on the contralateral side directly after implantation

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Visual-evoked cross-modal activity was also present on the contralateral side

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Monaural auditory stimulation elicited bilateral activity in listeners with two CIs

Effects of Sequential Bilateral Cochlear Implantation in Children: Evidence from Speech-Evoked Cortical Potentials and Tests of Speech Perception

INTRODUCTION

Benefits of bilateral cochlear implants (CI) may be compromised by delays to implantation of either ear. This study aimed to evaluate the effects of sequential bilateral CI use in children who received their first CI at young ages, using a clinical set-up.

METHODS

One-channel cortical auditory evoked potentials and speech perception in quiet and noise were evoked at repeated times (0, 3, 6, 12 months of bilateral CI use) by unilateral and bilateral stimulation in 28 children with early-onset deafness. These children were unilaterally implanted before 3.69 years of age (mean ± SD of 1.98 ± 0.73 years) and received a second CI after 5.13 ± 2.37 years of unilateral CI use. Comparisons between unilaterally evoked responses were used to measure asymmetric function between the ears and comparisons between bilateral responses and each unilateral response were used to measure the bilateral benefit.

RESULTS

Chronic bilateral CI promoted changes in cortical auditory responses and speech perception performance; however, large asymmetries were present between the two unilateral responses despite ongoing bilateral CI use. Persistent cortical differences between the two sides at 1 year of bilateral stimulation were predicted by increasing age at the first surgery and inter-implant delay. Larger asymmetries in speech perception occurred with longer inter-implant delays. Bilateral responses were more similar to the unilateral responses from the first rather than the second CI.

CONCLUSION

These findings are consistent with the development of the aural preference syndrome and reinforce the importance of providing bilateral CIs simultaneously or sequentially with very short delays.

The Role of the P1 Latency in Auditory and Speech Performance Evaluation in Cochlear Implanted Children

Auditory deprivation affects normal age-related changes in the central auditory maturation. Cochlear implants (CIs) have already become the best treatment strategy for severe to profound hearing impairment. However, it is still hard to evaluate the speech-language outcomes of the pediatric CI recipients because of hearing-impaired children with limited speech-language abilities. The cortical auditory evoked potential (CAEP) provides a window into the development of the auditory cortical pathways. This preliminary study is aimed at assessing electrophysical characteristics of P1-N1 of electrically CAEP in children with CIs and at exploring whether these changes could be accounted for in auditory and speech outcomes of these patients. CAEP responses were recorded in 48 children with CIs in response to electrical stimulus to determine the presence of the P1-N1 response. Speech perception and speech intelligibility of the implanted children were further evaluated with the categories of auditory performance (CAP) test and speech intelligibility rating (SIR) test, respectively, to explore the relationship between the latency of P1-N1 and auditory and speech performance. This study found that P1 and N1 of the intracochlear CAEP were reliably evoked in children fitted with CIs and that the latency of the P1 as opposed to that of N1 was negative in relation to the wearing time of the cochlear implant. Moreover, the latency of the P1 produced significantly negative scores in both CAP and SIR tests, which indicates that P1 latency may be reflective of the auditory performance and speech intelligibility of pediatric CI recipients. These results suggest that the latency of P1 could be used for the objective assessment of auditory and speech function evaluation in cochlear-implanted children, which would be helpful in clinical decision-making regarding intervention for young hearing-impaired children.

Neuroplasticity following cochlear implants

The auditory cortex of people with sensorineural hearing loss can be re-afferented using a cochlear implant (CI): a neural prosthesis that bypasses the damaged cells in the cochlea to directly stimulate the auditory nerve. Although CIs are the most successful neural prosthesis to date, some CI users still do not achieve satisfactory outcomes using these devices. To explain variability in outcomes, clinicians and researchers have increasingly focused their attention on neuroscientific investigations that examined how the auditory cortices respond to the electric signals that originate from the CI. This chapter provides an overview of the literature that examined how the auditory cortex changes its functional properties in response to inputs from the CI, in animal models and in humans. We focus first on the basic responses to sounds delivered through electrical hearing and, next, we examine the integrity of two fundamental aspects of the auditory system: tonotopy and processing of binaural cues. When addressing the effects of CIs in humans, we also consider speech-evoked responses. We conclude by discussing to what extent this neuroscientific literature can contribute to clinical practices and help to overcome variability in outcomes.

Cortical Auditory Evoked Potential in Adults With Cochlear Implants: A Comparison With Adults With Normal Hearing

Background and Objectives

To examine the maturational status of the auditory cortex in adults with cochlear implants (CIs) using the latencies of the P1, N1, and P2 components of cortical auditory-evoked potentials (CAEPs).

Subjects and Methods

A total of 25 adults with CIs and 25 age-matched, normal-hearing control subjects participated in this study. Specifically, patients with CIs were divided into three groups depending on their age of deafness onset: Group A comprised patients with prelingual deafness who had received CI during early childhood (n=7), Group B comprised patients with early childhood-onset, progressive deafness who had received CI during childhood (n=6), and Group C comprised patients with adult-onset deafness (n=12). The P1, N1, and P2 latencies of their CAEPs were then compared between CI patients and normal-hearing subjects.

Results

All participants showed clear CAEP responses. P1 and N1 latencies in Group A and Group C patients were significantly longer than those in the control group. Meanwhile, Group B patients had significantly longer N1 and P2 latencies, as compared with those in the control group.

Conclusions

Patients with prelingual deafness and those with early-childhood onset, progressive deafness who received CI developed primary and higher-order auditory areas postoperatively when they became adults. However, their auditory cortex maturational statuses seemed to be worse than that of normal-hearing individuals. Furthermore, adult patients with late-onset deafness might experience degenerative auditory cortex changes during the auditory deprivation period between deafness onset and cochlear implantation.

Can Haptic Stimulation Enhance Music Perception in Hearing-Impaired Listeners?

Cochlear implants (CIs) have been remarkably successful at restoring hearing in severely-to-profoundly hearing-impaired individuals. However, users often struggle to deconstruct complex auditory scenes with multiple simultaneous sounds, which can result in reduced music enjoyment and impaired speech understanding in background noise. Hearing aid users often have similar issues, though these are typically less acute. Several recent studies have shown that haptic stimulation can enhance CI listening by giving access to sound features that are poorly transmitted through the electrical CI signal. This “electro-haptic stimulation” improves melody recognition and pitch discrimination, as well as speech-in-noise performance and sound localization. The success of this approach suggests it could also enhance auditory perception in hearing-aid users and other hearing-impaired listeners. This review focuses on the use of haptic stimulation to enhance music perception in hearing-impaired listeners. Music is prevalent throughout everyday life, being critical to media such as film and video games, and often being central to events such as weddings and funerals. It represents the biggest challenge for signal processing, as it is typically an extremely complex acoustic signal, containing multiple simultaneous harmonic and inharmonic sounds. Signal-processing approaches developed for enhancing music perception could therefore have significant utility for other key issues faced by hearing-impaired listeners, such as understanding speech in noisy environments. This review first discusses the limits of music perception in hearing-impaired listeners and the limits of the tactile system. It then discusses the evidence around integration of audio and haptic stimulation in the brain. Next, the features, suitability, and success of current haptic devices for enhancing music perception are reviewed, as well as the signal-processing approaches that could be deployed in future haptic devices. Finally, the cutting-edge technologies that could be exploited for enhancing music perception with haptics are discussed. These include the latest micro motor and driver technology, low-power wireless technology, machine learning, big data, and cloud computing. New approaches for enhancing music perception in hearing-impaired listeners could substantially improve quality of life. Furthermore, effective haptic techniques for providing complex sound information could offer a non-invasive, affordable means for enhancing listening more broadly in hearing-impaired individuals.

Auditory Event Related Potentials in children with autism spectrum disorder

OBJECTIVE

To analyze auditory cortical processing in high functioning ASD individuals.

METHODS

Thirty individuals were included in the study (15 with Autism Spectrum Disorder and 15 with typical development), and their Auditory Event Related Potentials evaluation, elicited with tone burst and speech stimuli, were analyzed.

RESULTS

There were no significant differences between individuals with high-functioning Autism Spectrum Disorder without intellectual disability and those with typical development in the auditory Event-related Potentials elicited with tone bursts or speech stimuli.

CONCLUSIONS

The results of Auditory Event Related Potentials did not show any change at the cortical level in individuals with Autism Spectrum Disorder.

Electro-Tactile Stimulation Enhances Cochlear-Implant Melody Recognition: Effects of Rhythm and Musical Training

OBJECTIVES

Electro-acoustic stimulation (EAS) enhances speech and music perception in cochlear-implant (CI) users who have residual low-frequency acoustic hearing. For CI users who do not have low-frequency acoustic hearing, tactile stimulation may be used in a similar fashion as residual low-frequency acoustic hearing to enhance CI performance. Previous studies showed that electro-tactile stimulation (ETS) enhanced speech recognition in noise and tonal language perception for CI listeners. Here, we examined the effect of ETS on melody recognition in both musician and nonmusician CI users.

DESIGN

Nine musician and eight nonmusician CI users were tested in a melody recognition task with or without rhythmic cues in three testing conditions: CI only (E), tactile only (T), and combined CI and tactile stimulation (ETS).

RESULTS

Overall, the combined electrical and tactile stimulation enhanced the melody recognition performance in CI users by 9% points. Two additional findings were observed. First, musician CI users outperformed nonmusicians CI users in melody recognition, but the size of the enhancement effect was similar between the two groups. Second, the ETS enhancement was significantly higher with nonrhythmic melodies than rhythmic melodies in both groups.

CONCLUSIONS

These findings suggest that, independent of musical experience, the size of the ETS enhancement depends on integration efficiency between tactile and auditory stimulation, and that the mechanism of the ETS enhancement is improved electric pitch perception. The present study supports the hypothesis that tactile stimulation can be used to improve pitch perception in CI users.

Can a Self-report Measure Be Used to Assess Cognitive Skills in Adults With Hearing Loss?

HYPOTHESES

Adult cochlear implant candidates would self-report their executive functioning abilities as poorer than normal-hearing peers. These executive function abilities would correlate with laboratory-based cognitive tests. Lastly, executive functioning (EF) abilities would be associated with hearing-related quality of life.

BACKGROUND

Executive function refers to cognitive abilities involved in behavioral regulation during goal-directed activity. Pediatric and adult users have demonstrated delays and deficits in executive function skills compared with normal-hearing peers. This study aimed to compare self-report executive function in adult cochlear implant candidates and normal-hearing peers and to relate executive function skills to laboratory-based cognitive testing and hearing-related quality of life.

METHODS

Twenty-four postlingually deaf adult cochlear implant candidates were enrolled, along with 42 normal-hearing age-matched peers. Participants completed self-reports of executive function using the Behavior Rating Inventory of Executive Function- Adult (BRIEF-A). Participants were also tested using laboratory-based cognitive measures, as well as assessment of hearing-related quality of life on the Nijmegen Cochlear Implant Questionnaire. Groups were compared on BRIEF-A scores, and relations between BRIEF-A and lab-based cognitive measures as well as Nijmegen Cochlear Implant Questionnaire scores were examined.

RESULTS

Self-report executive function on the BRIEF-A was not significantly different between groups. Consistent relations of self-report executive function and nonverbal reasoning were identified. Strong relations were not found between self-report executive function and hearing-related quality of life.

CONCLUSIONS

Executive function as measured by BRIEF-A demonstrates some relation with a laboratory-based metric of nonverbal reasoning, but not other cognitive measures. Hearing-impaired individuals did not report poorer EF than normal-hearing controls. EF additionally did not correlate with quality of life. Our findings provide preliminary, partial validation of the BRIEF-A instrument in the preoperative evaluation of adult cochlear implant candidates.

Listening Difficulties of Children With Cochlear Implants in Mainstream Secondary Education

OBJECTIVES

Previous research has shown that children with cochlear implants (CIs) encounter more communication difficulties than their normal-hearing (NH) peers in kindergarten and elementary schools. Yet, little is known about the potential listening difficulties that children with CIs may experience during secondary education. The aim of this study was to investigate the listening difficulties of children with a CI in mainstream secondary education and to compare these results to the difficulties of their NH peers and the difficulties observed by their teachers.

DESIGN

The Dutch version of the Listening Inventory for Education Revised (LIFE-R) was administered to 19 children (mean age = 13 years 9 months; SD = 9 months) who received a CI early in life, to their NH classmates (n = 239), and to their teachers (n = 18). All participants were enrolled in mainstream secondary education in Flanders (first to fourth grades). The Listening Inventory for Secondary Education consists of 15 typical listening situations as experienced by students (LIFEstudent) during class activities (LIFEclass) and during social activities at school (LIFEsocial). The teachers completed a separate version of the Listening Inventory for Secondary Education (LIFEteacher) and Screening Instrument for Targeting Educational Risk.

RESULTS

Participants with CIs reported significantly more listening difficulties than their NH peers. A regression model estimated that 75% of the participants with CIs were at risk of experiencing listening difficulties. The chances of experiencing listening difficulties were significantly higher in participants with CIs for 7 out of 15 listening situations. The 3 listening situations that had the highest chance of resulting in listening difficulties were (1) listening during group work, (2) listening to multimedia, and (3) listening in large-sized classrooms. Results of the teacher's questionnaires (LIFEteacher and Screening Instrument for Targeting Educational Risk) did not show a similar significant difference in listening difficulties between participants with a CI and their NH peers. According to teachers, NH participants even obtained significantly lower scores for staying on task and for participation in class than participants with a CI.

CONCLUSIONS

Although children with a CI seemingly fit in well in mainstream schools, they still experience significantly more listening difficulties than their NH peers. Low signal to noise ratios (SNRs), distortions of the speech signal (multimedia, reverberation), distance, lack of visual support, and directivity effects of the microphones were identified as difficulties for children with a CI in the classroom. As teachers may not always notice these listening difficulties, a list of practical recommendations was provided in this study, to raise awareness among teachers and to minimize the difficulties.

Cochlear Implantation in Children With Single-Sided Deafness: A Systematic Review and Meta-analysis

Importance

In 2019, the US Food and Drug Administration approved cochlear implantation for children with single-sided deafness (SSD). The absence of robust clinical data specific to pediatric patients to guide shared decision-making and to identify potential advantages is a challenge in family counseling.

Objective

To evaluate the audiological and patient-reported outcomes in children who underwent cochlear implantation for SSD and to assess the association between time of implantation, subjective outcomes, and cochlear implant device use rates.

Data Source

MEDLINE, Embase, Scopus, Cochrane, and PubMed were searched for English-language articles that were published in a peer-reviewed journal from database inception to February 18, 2020.

Study Selection

Inclusion criteria were designed to capture studies that evaluated pediatric patients (1) younger than 18 years, (2) with a diagnosis of SSD for which they underwent a cochlear implantation, and (3) with at least 1 outcome of interest measured numerically: speech perception, sound localization, device use, and patient-reported outcomes. Of the 526 articles reviewed, 12 (2.3%) met the selection criteria.

Data Extraction and Synthesis

The Meta-analyses Of Observational Studies in Epidemiology (MOOSE) reporting guidelines were followed. Data were pooled using fixed-effect and random-effect models. The following information was obtained from each article: study characteristics, patient characteristics, hearing loss and intervention characteristics, and outcomes.

Main Outcomes and Measures

Outcomes were (1) postoperative changes in speech perception (in quiet was measured as a proportion of correct responses, and in noise was measured as decibel signal to noise ratio for speech reception threshold) and sound localization (measured in degree of localization error), (2) patient-reported audiological outcomes (measured by the speech, spatial, and qualities of hearing scale), and (3) device use rates among children who received cochlear implantation for SSD.

Results

Twelve observational studies that evaluated 119 children (mean [SD] age, 6.6 [4.0] years) with SSD who received a cochlear implant were included. Most children showed clinically meaningful improvement in speech perception in noise (39 of 49 children [79.6%]) and in quiet (34 of 42 children [81.0%]). Long duration of deafness (>4 years in congenital SSD and >7 years in perilingual SSD) was the most commonly proposed reason for lack of improvement. Sound localization as measured by degrees of error from true location (mean difference [MD], -24.78°; 95% CI, -34.16° to -15.40°; I2 = 10%) improved statistically significantly after cochlear implantation. Patients with acquired SSD and shorter duration of deafness compared with those with congenital SSD reported greater improvements in speech (MD, 2.27; 95% CI, 1.89-2.65 vs 1.58; 95% CI, 1.00-2.16) and spatial (MD, 2.95; 95% CI, 2.66-3.24 vs 1.68; 95% CI, 0.96-2.39) hearing qualities. The duration of deafness among device nonusers was statistically significantly longer than the duration of deafness among regular device users (median difference, 6.84; 95% CI, 4.02-9.58).

Conclusions and Relevance

This systematic review and meta-analysis found that cochlear implantation for children with SSD was associated with clinically meaningful improvements in audiological and patient-reported outcomes; shorter duration of deafness may lead to better outcomes. These findings can guide future research efforts, refine cochlear implantation candidacy criteria, and aid in family counseling and shared decision-making.

Sequential Bilateral Cochlear Implantation With Prolonged Time Intervals

Purpose The aim of the study was to assess whether sequential cochlear implantation (CI) with a prolonged interimplant interval (M = 15.2 years) between the first and second CIs benefited speech recognition and health-related quality of life. Method This prospective study included 14 prelingually deafened participants who received their second CI after a prolonged interimplant interval (M = 15.2 years). Additionally, speech recognition ability over a 12-month period of bilateral implant use was investigated. The results of the speech recognition test in both quiet and noisy conditions were statistically analyzed for each CI alone and both CIs together. Nijmegen Cochlear Implant Questionnaire scores were also collected at activation and at 12 months after activation. Results Improvements in speech recognition ability were observed following the use of the first implant alone and with the use of both implants together; however, progress was much slower with the use of the second implant alone, following its introduction. Furthermore, a significant difference in the trajectory of speech recognition ability was observed between the first and the second implanted ear. According to Nijmegen Cochlear Implant Questionnaire scores, all participants benefitted from bilateral CI after 12 months. Conclusions Prolonged interimplant intervals resulted in asymmetrical speech recognition abilities. A significant improvement in the speech recognition scores was observed with the first implanted ear, and much slower progress was observed with the second implanted ear. However, the "poorer" second implanted ear could provide a considerable beneficial effect on the improved speech recognition and health-related quality of life with the bilateral CI. Supplemental Material https://doi.org/10.23641/asha.12861152.

Auditory Performance in Late Implanted Congenitally Hearing Impaired Children: A Reality Check

The present study aimed at determining auditory performance in children with congenital hearing impairment who underwent cochlear implant surgery unilaterally at or after age of 5 years. Study also aimed at studying association of factors such as chronological age (CA), implant age (IA), age at implantation (AAI), hearing age (HA), parental support, compliance to therapy, mode of therapy and parental satisfaction with auditory performance. It is a retrospective study. Files of 41 participants who fulfilled the inclusion criteria were reviewed for scores of Revised categories of auditory perception (CAP), Listening skills scale (LSS) and Speech intelligibility rating (SIR) along with other factors. Only 20 participants with complete data were included in the study. Researcher rated parental support and compliance to therapy while parental satisfaction was noted prospectively using a single yes-no type question. Participants showed improvement on CAP, LSS, SIR however they did not reach normal or near normal scores. CAP and LSS did not correlate with CA nor AAI or with IA. However CAP and LSS showed significant correlation with HA. SIR showed significant correlation with CA, AAI, IA and HA. Good auditory performance was associated with parental support and compliance to therapy but not with mode of therapy offered. 17 out of 20 parents were satisfied with outcomes of cochlear implant. Late implanted children showed improved auditory performance with implantation when they had previous hearing aid experience and parent support and compliance to therapy though they did not reach normal levels.

The Benefit of Cross-Modal Reorganization on Speech Perception in Pediatric Cochlear Implant Recipients Revealed Using Functional Near-Infrared Spectroscopy

Cochlear implants (CIs) are the most successful treatment for severe-to-profound deafness in children. However, speech outcomes with a CI often lag behind those of normally-hearing children. Some authors have attributed these deficits to the takeover of the auditory temporal cortex by vision following deafness, which has prompted some clinicians to discourage the rehabilitation of pediatric CI recipients using visual speech. We studied this cross-modal activity in the temporal cortex, along with responses to auditory speech and non-speech stimuli, in experienced CI users and normally-hearing controls of school-age, using functional near-infrared spectroscopy. Strikingly, CI users displayed significantly greater cortical responses to visual speech, compared with controls. Importantly, in the same regions, the processing of auditory speech, compared with non-speech stimuli, did not significantly differ between the groups. This suggests that visual and auditory speech are processed synergistically in the temporal cortex of children with CIs, and they should be encouraged, rather than discouraged, to use visual speech.

Early exposure to environment sounds and the development of cortical auditory evoked potentials of preterm infants during the first 3 months of life

OBJECTIVE

Preterm infants are exposed earlier than their term counterparts to unattenuated sounds from the external environment during the sensitive period of the organization of the auditory cortical circuitry. In the current study, we investigate the effect of preterm birth on the course of development of auditory cortical areas by evaluating how gestational age (GA) correlates with the latency of the P1 component of the cortical auditory evoked potential (CAEP) of two experimental groups measured at 1 or 3 months of age.

RESULTS

Our sample consisted of 23 infants delivered at GA ranging from 31.28 to 41.42 weeks and separated into two groups evaluated transversally at 1 or 3 months of corrected age (CA). In the group evaluated at 1-month CA, the latency of the component P1 was similar in both terms and infants classified as late-preterm (GA > 32 weeks). However, in the group evaluated at 3 months CA, P1 latency was significantly smaller in preterms. These preliminary results suggest an acceleration of the development of auditory cortical pathways in preterms, probably due to their early exposure to socially relevant auditory stimuli from the external environment.

Communication Mode and Speech and Language Outcomes of Young Cochlear Implant Recipients: A Comparison of Auditory-Verbal, Oral Communication, and Total Communication

OBJECTIVE

To evaluate the effect of communication mode on the spoken language outcomes of children who received a cochlear implant.

STUDY DESIGN

Retrospective analysis of postoperative speech and language and reading scores for children who received a cochlear implant and used three different modes of communication: auditory-verbal (AV) (n = 39), oral communication (OC) (n = 107), and total communication (TC) (n = 57).

SETTING

A single tertiary cochlear implant clinic.

PATIENTS

All children received their cochlear implant before the age of 5 years, had no known cochlear anomaly or cognitive delay that would affect their outcome with the CI, and had established consistent use of their respective communication methodology.

INTERVENTION

Rehabilitation varied depending on the selected communication methodology. Data were collected during routine postoperative speech and language evaluations.

MAIN OUTCOME MEASURES

Receptive and expressive language, reading comprehension, and speech intelligibility scores obtained up to 7 years post-activation of a cochlear implant.

RESULTS

All groups showed improvements over time. Linear mixed model analyses indicated scores obtained by children in the AV group were significantly higher than mean scores obtained by children in the other groups on most test measures at most post-implant intervals. Significantly greater numbers of children in the AV group obtained standard scores within normal limits than children in the OC and TC groups.

CONCLUSIONS

These findings support the use of the auditory-verbal communication approach to facilitate development of age-appropriate speech and language and literacy skills in profoundly deaf children.

Impact of Universal Newborn Hearing Screening on cochlear implanted children in Ireland

OBJECTIVES

Cochlear Implant (CI) is an established treatment for severe to profound hearing loss (HL). Early diagnosis and intervention in HL are crucial in order to provide access to sound and increase the likelihood of spoken language development in pre-lingually deaf children. In April 2011, the Health Service Executive (HSE) implemented the Universal Newborn Hearing Screening (UNHS) in a phased regional basis in Ireland. This study aimed to investigate the general clinical pathway for UNHS referrals to the CI service and to evaluate the impact of earlier referrals via UNHS on functional outcomes in children.

METHODS

The first part of this study constituted a retrospective review of 100 children referred to the National Hearing Implant and Research Centre (NHIRC) via UNHS from November 2011 to December 2016. Implanted children referred via UNHS were categorised into three groups according to their medical status. Their clinical pathway to cochlear implantation was evaluated. Functional outcomes were investigated based on medical and developmental status, respectively. In the second part of this study, developmentally healthy implanted children referred post-UNHS were compared with medically healthy children referred pre-UNHS under the age of four, from January 2005 to June 2011. Current implant status of children, age at referral and functional outcomes were investigated.

RESULTS

Medically healthy children were referred to the NHIRC at an earlier age than the medically complex children (2.8 months vs 5.2 months, p < 0.01) and the children presenting with auditory neuropathy spectrum disorder (ANSD) (2.8 months vs 5.3 months, p < 0.01). On average they attended their first appointment and were implanted at a younger age than the ANSD group (6.1 months vs 10.1 months, p < 0.01; 16.3 months vs 29.4 months, p < 0.001, respectively). Developmentally healthy children had significantly better functional outcomes than children with developmental delays. Children referred via UNHS were referred and implanted at a younger age than those referred pre-UNHS. The former group achieved better Categories of Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) scores 2 years post-implantation.

CONCLUSION

UNHS in Ireland is an important platform for earlier diagnosis and management of congenital HL and our results show that early intervention has a positive impact on functional outcomes in children.

Compensatory Cross-Modal Plasticity Persists After Sight Restoration

Sensory deprivation prompts extensive structural and functional reorganizations of the cortex resulting in the occupation of space for the lost sense by the intact sensory systems. This process, known as cross-modal plasticity, has been widely studied in individuals with vision or hearing loss. However, little is known on the neuroplastic changes in restoring the deprived sense. Some reports consider the cross-modal functionality maladaptive to the return of the original sense, and others view this as a critical process in maintaining the neurons of the deprived sense active and operational. These controversial views have been challenged in both auditory and vision restoration reports for decades. Recently with the approval of Luxturna as the first retinal gene therapy (GT) drug to reverse blindness, there is a renewed interest for the crucial role of cross-modal plasticity on sight restoration. Employing a battery of task and resting state functional magnetic resonance imaging (rsfMRI), in comparison to a group of sighted controls, we tracked the functional changes in response to auditory and visual stimuli and at rest, in a group of patients with biallelic mutations in the RPE65 gene (“RPE65 patients”) before and 3 years after GT. While the sighted controls did not present any evidence for auditory cross-modal plasticity, robust responses to the auditory stimuli were found in occipital cortex of the RPE65 patients overlapping visual responses and significantly elevated 3 years after GT. The rsfMRI results showed significant connectivity between the auditory and visual areas for both groups albeit attenuated in patients at baseline but enhanced 3 years after GT. Taken together, these findings demonstrate that (1) RPE65 patients present with an auditory cross-modal component; (2) visual and non-visual responses of the visual cortex are considerably enhanced after vision restoration; and (3) auditory cross-modal functions did not adversely affect the success of vision restitution. We hypothesize that following GT, to meet the demand for the newly established retinal signals, remaining or dormant visual neurons are revived or unmasked for greater participation. These neurons or a subset of these neurons respond to both the visual and non-visual demands and further strengthen connectivity between the auditory and visual cortices.

Altered Gray Matter Volume and White Matter Integrity in Sensorineural Hearing Loss Patients: A VBM and TBSS Study

OBJECTIVE

The purpose of the present study was to detect structural changes in the brains of patients with sensorineural hearing loss (SNHL) by combining voxel-based morphometry (VBM) and tract-based spatial statistics (TBSS).

METHODS

Thirty-five patients with SNHL (mean age: 39.72 ± 1.81 yr) and 23 age-matched control subjects (mean age: 39.83 ± 1.96 yr) were assessed using three-dimensional, T1-weighted imaging, and diffusion tensor imaging. TBSS and VBM analyses were performed to evaluate grey matter (GM) volume changes and white matter (WM) alternations, as measured by mean diffusivity (MD), fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD).

RESULTS

VBM showed decreased GM volume in patients with SNHL in the fusiform gyrus of the right temporal lobe and right middle occipital gyrus. TBSS revealed WM integrity changes, including decreased FA and RD and increased RD in several WM regions. However, MD showed no significant difference between patients with SNHL and age-matched controls.

CONCLUSION

Patients with SNHL showed smaller GM volume and WM integrity changes in several regions.

Assessment of Cortical Auditory Function Using Electrophysiological and Neuropsychological Measurements in Children with Bone-Anchored Hearing Aids

Children suffering from conductive or mixed hearing loss may benefit from a bone-anchored hearing aid system (BAHA Attract implantable prosthesis). After audiological rehabilitation, different aspects of development are improving. The objective of this case report is to propose a comprehensive framework for monitoring cortical auditory function after implantation of a bone-anchored hearing aid system by using electrophysiological and neuropsychological measurements.

We present the case of a seven-year-old boy with a congenital hearing loss due to a plurimalformative syndrome, including outer and middle ear malformation. After the diagnosis of hearing loss and the audiological rehabilitation with a BAHA Attract implantable prosthesis, the cortical auditory evoked potentials were recorded. We performed a neuropsychological evaluation using the Wechsler Intelligence Scale for Children – Fourth Edition, which was applied according to a standard procedure.

The P1 latency was delayed according to the age (an objective biomarker for quantifying cortical auditory function). The neuropsychological evaluation revealed that the child's working memory and verbal reasoning abilities were in the borderline range comparing with his nonverbal reasoning abilities and processing abilities, which were in the average and below-average range, respectively.

Cortical auditory evoked potentials, along with neuropsychological evaluation, could be an essential tool for monitoring cortical auditory function in children with hearing loss after a bone-anchored hearing aid implantation.

Independent component analysis for cochlear implant artifacts attenuation from electrically evoked auditory steady-state response measurements

OBJECTIVE

Electrically evoked auditory steady-state responses (EASSRs) are potentially useful for objective cochlear implant (CI) fitting and follow-up of the auditory maturation in infants and children with a CI. EASSRs are recorded in the electro-encephalogram (EEG) in response to electrical stimulation with continuous pulse trains, and are distorted by significant CI artifacts related to this electrical stimulation. The aim of this study is to evaluate a CI artifacts attenuation method based on independent component analysis (ICA) for three EASSR datasets.

APPROACH

ICA has often been used to remove CI artifacts from the EEG to record transient auditory responses, such as cortical evoked auditory potentials. Independent components (ICs) corresponding to CI artifacts are then often manually identified. In this study, an ICA based CI artifacts attenuation method was developed and evaluated for EASSR measurements with varying CI artifacts and EASSR characteristics. Artifactual ICs were automatically identified based on their spectrum.

MAIN RESULTS

For 40 Hz amplitude modulation (AM) stimulation at comfort level, in high SNR recordings, ICA succeeded in removing CI artifacts from all recording channels, without distorting the EASSR. For lower SNR recordings, with 40 Hz AM stimulation at lower levels, or 90 Hz AM stimulation, ICA either distorted the EASSR or could not remove all CI artifacts in most subjects, except for two of the seven subjects tested with low level 40 Hz AM stimulation. Noise levels were reduced after ICA was applied, and up to 29 ICs were rejected, suggesting poor ICA separation quality.

SIGNIFICANCE

We hypothesize that ICA is capable of separating CI artifacts and EASSR in case the contralateral hemisphere is EASSR dominated. For small EASSRs or large CI artifact amplitudes, ICA separation quality is insufficient to ensure complete CI artifacts attenuation without EASSR distortion.

N400 and short speech stimuli

In some children who have cochlear implants (CI), the expected speech-language outcome is not achieved despite fulfilment of requirements for its successful use. This may be attributed to processing difficulties at higher levels of the auditory pathway. The aim of this study was to investigate the processing of speech stimuli at the auditory-cortex level in 20 children aged 8 to 10 years who have a hearing impairment and have been using cochlear implants, by means of cortical auditory evoked potentials (CAEP). The children were divided into two groups, depending on the outcome: 10 successful implant users and 10 unsuccessful implant users, whose speech-language development has not progressed as expected. The control group comprised of 10 age-matched children with typical hearing and speech-language development. Two double consonant+vowel syllables (CVCV) were used as stimuli, presented in an oddball paradigm that required the subjects to react consciously. Latencies and amplitudes of CAEP waves were measured. In addition to the waves that typically occur in CAEP and reflect auditory processing at the level of the auditory cortex, N400 wave (associated with semantic processing) was recorded in the normally hearing group and successful CI users, but not in the unsuccessful CI users. Additionally, successful CI users and controls had comparable latencies of the P300 wave (preceding the N400) as well. Although P300 and N400 reflect two processes, they are related so that if P300 does not reach the expected amplitude and latency, neither will N400.

Somatosensory Cross-Modal Reorganization in Children With Cochlear Implants

Deprived of sensory input, as in deafness, the brain tends to reorganize. Cross-modal reorganization occurs when cortices associated with deficient sensory modalities are recruited by other, intact senses for processing of the latter's sensory input. Studies have shown that this type of reorganization may affect outcomes when sensory stimulation is later introduced via intervention devices. One such device is the cochlear implant (CI). Hundreds of thousands of CIs have been fitted on people with hearing impairment worldwide, many of them children. Factors such as age of implantation have proven useful in predicting speech perception outcome with these devices in children. However, a portion of the variance in speech understanding ability remains unexplained. It is possible that the degree of cross-modal reorganization may explain additional variability in listening outcomes. Thus, the current study aimed to examine possible somatosensory cross-modal reorganization of the auditory cortices. To this end we used high density EEG to record cortical responses to vibrotactile stimuli in children with normal hearing (NH) and those with CIs. We first investigated cortical somatosensory evoked potentials (CSEP) in NH children, in order to establish normal patterns of CSEP waveform morphology and sources of cortical activity. We then compared CSEP waveforms and estimations of cortical sources between NH children and those with CIs to assess the degree of somatosensory cross-modal reorganization. Results showed that NH children showed expected patterns of CSEP and current density reconstructions, such that postcentral cortices were activated contralaterally to the side of stimulation. Participants with CIs also showed this pattern of activity. However, in addition, they showed activation of auditory cortical areas in response to somatosensory stimulation. Additionally, certain CSEP waveform components were significantly earlier in the CI group than the children with NH. These results are taken as evidence of cross-modal reorganization by the somatosensory modality in children with CIs. Speech perception in noise scores were negatively associated with CSEP waveform components latencies in the CI group, suggesting that the degree of cross-modal reorganization is related to speech perception outcomes. These findings may have implications for clinical rehabilitation in children with cochlear implants.

Cochlear Implantation for Children and Adults with Severe-to-Profound Hearing Loss

Cochlear implants (CIs) have proven to be a useful treatment option for individuals with severe-to-profound hearing loss by providing improved access to one's surrounding auditory environment. CIs differ from traditional acoustic amplification by providing information to the auditory system via electrical stimulation. Both postlingually deafened adults and prelingually deafened children can benefit from a CI; however, outcomes with a CI can vary. Numerous factors can impact performance outcomes with a CI. It is important for the audiologist to understand what factors might play a role and impact performance outcomes with a CI so that they can effectively counsel the recipient and their family, as well as establish appropriate and realistic expectations with a CI. This review article will discuss the CI candidacy process, CI programming and postoperative follow-up care, as well as considerations across the lifespan that may affect performance outcomes with a CI.

Comparing Auditory-Only and Audiovisual Word Learning for Children With Hearing Loss

Although reducing visual input to emphasize auditory cues is a common practice in pediatric auditory (re)habilitation, the extant literature offers minimal empirical evidence for whether unisensory auditory-only (AO) or multisensory audiovisual (AV) input is more beneficial to children with hearing loss for developing spoken language skills. Using an adapted alternating treatments single case research design, we evaluated the effectiveness and efficiency of a receptive word learning intervention with and without access to visual speechreading cues. Four preschool children with prelingual hearing loss participated. Based on probes without visual cues, three participants demonstrated strong evidence for learning in the AO and AV conditions relative to a control (no-teaching) condition. No participants demonstrated a differential rate of learning between AO and AV conditions. Neither an inhibitory effect predicted by a unisensory theory nor a beneficial effect predicted by a multisensory theory for providing visual cues was identified. Clinical implications are discussed.

Cochlear Implantation: An Overview

A cochlear implant (CI) is a surgically implanted device for the treatment of severe to profound sensorineural hearing loss in children and adults. It works by transducing acoustic energy into an electrical signal, which is used to stimulate surviving spiral ganglion cells of the auditory nerve. The past 2 decades have witnessed an exponential rise in the number of CI surgeries performed. Continual developments in programming strategies, device design, and minimally traumatic surgical technique have demonstrated the safety and efficacy of CI surgery. As a result, candidacy guidelines have expanded to include both pre and postlingually deaf children as young as 1 year of age, and those with greater degrees of residual hearing. A growing proportion of patients are undergoing CI for off-label or nontraditional indications including single-sided deafness, retrocochlear hearing loss, asymmetrical sensorineural hearing loss (SNHL) in adults and children with at least 1 ear that is better than performance cut-off for age, and children less than 12 months of age. Herein, we review CI design, clinical evaluation, indications, operative technique, and outcomes. We also discuss the expanding indications for CI surgery as it relates to lateral skull base pathology, comparing CI to auditory brainstem implants, and address the concerns with obtaining magnetic resonance imaging (MRI) in CI recipients.

Sequential bilateral cochlear implant: results in children and adolescents

Introduction

The use of the bilateral cochlear implants can promote the symmetrical development of the central auditory pathways, thus benefiting the development of auditory abilities and improving sound localization and the ability of auditory speech perception in situations of competitive noise.

Objective

To evaluate the ability of speech perception in children and adolescents using sequential bilateral cochlear implants, considering the association of these variables: age at surgery, time of device use and interval between surgeries.

Methods

A total of 14 individuals between 10 and 16 years of age, who demonstrated surgical indication for the use of sequential bilateral cochlear implants as intervention in the auditory habilitation process, were assessed. The speech perception ability was assessed through sentence lists constructed in the Portuguese language, presented in two situations: in silence, with fixed intensity of 60 dB SPL, and in competitive noise, with a signal-to-noise ratio of +15 dB. The evaluation was performed under the following conditions: unilateral with the first activated cochlear implant, unilateral with the second activated cochlear implant and bilateral with both devices activated.

Results

The results of the speech perception tests showed better performance in both silence and in noise for the bilateral cochlear implant condition when compared to the 1st cochlear implant and the 2nd cochlear implant alone. A worse result of speech perception was found using the 2nd cochlear implant alone. No statistically significant correlation was found between age at the surgical procedure, interval between surgeries and the time of use of the 2nd cochlear implant, and the auditory speech perception performance for all assessed conditions. The use of a hearing aid prior to the 2nd cochlear implant resulted in benefits for auditory speech perception with the 2nd cochlear implant, both in silence and in noise.

Conclusion

The bilateral cochlear implant provided better speech perception in silence and in noise situations when compared to the unilateral cochlear implant, regardless of the interval between surgeries, age at the surgical procedure and the time of use of the 2nd cochlear implant. Speech perception with the 1st cochlear implant was significantly better than with the 2nd cochlear implant, both in silence and in noise. The use of the hearing aid prior to the 2nd cochlear implant influenced speech perception performance with the 2nd cochlear implant, both in silence and in noise.