Bilateral paediatric cochlear implants: a critical review

Hollow ring-like flexible electrode architecture enabling subcellular multi-directional neural interfacing

Implantable neural microelectrodes for recording and stimulating neural activity are critical for research in neuroscience and clinical neuroprosthetic applications. A current need exists for developing new technological solutions for obtaining highly selective and stealthy electrodes that provide reliable neural integration and maintain neuronal viability. This paper reports a novel Hollow Ring-like type electrode to sense and/or stimulate neural activity from three-dimensional neural networks. Due to its unique design, the ring electrode architecture enables easy and reliable access of the electrode to three-dimensional neural networks with reduced mechanical contact on the biological tissue, while providing improved electrical interface with cells. The Hollow Ring electrodes, particularly when coated with the conducting polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), show improved electrical properties with extremely low impedance (7 MΩ μm²) and high charge injection capabilities (15 mC/cm²), when compared to traditional planar disk-type electrodes. The ring design also serves as an optimal architecture for cell growth to create an optimal subcellular electrical-neural interface. In addition, we showed that neural signals recorded by the ring electrode were better resolved than recordings from a traditional disk-type electrode improving the signal-to-noise ratio (SNR) and the burst detection from 3D neuronal networks in vitro. Overall, our results suggest the great potential of the hollow ring design for developing next-generation microelectrodes for applications in neural interfaces used in physiological studies and neuromodulation applications.

Simultaneous Bilateral Cochlear Implantation in Very Young Children Improves Adaptability and Social Skills: A Prospective Cohort Study

OBJECTIVES

To investigate the value of using the Gesell Development Diagnosis Scale (GDDS) to predict developmental outcomes in very young children who undergo simultaneous bilateral cochlear implantation.

DESIGN

In this prospective cohort study, a repeated-measures investigation was conducted in a tertiary referral hospital. A total of 62 children receiving simultaneous bilateral cochlear implantations were enrolled from April 2017 to August 2018. They were divided into 2 groups depending on the operative age: "Infants" group (6 to 12 months, N = 38) or "Children" group (12 to 36 months, N = 24). Data on the surgical outcomes, auditory development, speech production, and developmental indicators were collected until 2 years after the initial fitting. The primary outcome measure was the GDDS, a neuropsychological development examination. Secondary outcomes included the following: complication rate, aided pure-tone average, Infant-Toddler Meaningful Auditory Integration Scale, Categories of Auditory Performance-II, Meaningful Use of Speech Scale, Speech Intelligibility Rating, and the LittlEARS Auditory Questionnaire.

RESULTS

The mean ages at implantation in infants and children groups were 9.2 ± 1.17 and 16.6 ± 3.60 months, respectively. Significant differences were found in the social skills ( p = 0.001) and adaptability ( p = 0.031) domains of GDDS. The younger the age of bilateral cochlear implants surgery, the higher developmental quotient of language, social skills, and adaptability the child could achieve after 2 years. The complication rates in the infants and children groups were 0% versus 2.1% ( p = 0.57). There was no surgical complication in the infants group. In the children group, 1 case with enlarged vestibular aqueduct and Mondini malformation had a receiver-implant misplacement on the right side (2%, 1/48). In the two groups, auditory performance and speech production had improved similarly. In the infants group, social skills developmental quotient at baseline had a significant positive relationship with Meaningful Use of Speech Scale after 2 years.

CONCLUSIONS

Simultaneous bilateral cochlear implantation in younger children improves adaptability and social skills. GDDS is a sensitive tool of evaluating short-term effect of bilateral cochlear implants in neuropsychological development and constitutes a reliable predictor of speech production for the very younger pediatric cochlear implant users.

Advanced strategies to thwart foreign body response to implantable devices

Mitigating the foreign body response (FBR) to implantable medical devices (IMDs) is critical for successful long-term clinical deployment. The FBR is an inevitable immunological reaction to IMDs, resulting in inflammation and subsequent fibrotic encapsulation. Excessive fibrosis may impair IMDs function, eventually necessitating retrieval or replacement for continued therapy. Therefore, understanding the implant design parameters and their degree of influence on FBR is pivotal to effective and long lasting IMDs. This review gives an overview of FBR as well as anti-FBR strategies. Furthermore, we highlight recent advances in biomimetic approaches to resist FBR, focusing on their characteristics and potential biomedical applications.

A Modified Pediatric Ranked Order Speech Perception Score to Assess Speech Recognition Development in Children With Cochlear Implants

PURPOSE

Characterizing and comparing speech recognition development in children with cochlear implants (CIs) is challenging because of variations in test type. This retrospective cohort study modified the Pediatric Ranked Order Speech Perception (PROSPER) scoring system to (a) longitudinally analyze the speech perception of children with CIs and (b) examine the role of age at CI activation, listening mode (i.e., unilateral or bilateral implantation), and interimplant interval.

METHOD

Postimplantation speech recognition scores from 31 children with prelingual, severe-to-profound hearing loss who received CIs were analyzed (12 with unilateral CI [UniCI], 13 with sequential bilateral CIs [SEQ BiCIs], and six with simultaneous BiCIs). Data were extracted from the Massachusetts Eye and Ear Audiology database. A version of the PROSPER score was modified to integrate the varying test types by mapping raw scores from different tests into a single score. The PROSPER scores were used to construct speech recognition growth curves of the implanted ears, which were characterized by the slope of the growth phase, the time from activation to the plateau onset, and the score at the plateau.

RESULTS

While speech recognition improved considerably for children following implantation, the growth rates and scores at the plateau were highly variable. In first implanted ears, later implantation was associated with poorer scores at the plateau (β = -0.15, p = .01), but not growth rate. The first implanted ears of children with BiCIs had better scores at the plateau than those with UniCI (β = 0.59, p = .02). Shorter interimplant intervals in children with SEQ BiCIs promoted faster speech recognition growth of the first implanted ears.

CONCLUSION

The modified PROSPER score could be used clinically to track speech recognition development in children with CIs, to assess influencing factors, and to assist in developing and evaluating patient-specific intervention strategies.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.20113538.

Vocabulary Growth in Mandarin-Speaking Children With Bilateral Cochlear Implants, Bimodal Stimulation, or Unilateral Cochlear Implants During the First Year After Activation

PURPOSE

The purpose of this study was to evaluate vocabulary development in Mandarin-speaking children with bilateral cochlear implants (CIs), bimodal stimulation (CI plus hearing aids [HAs]), or unilateral CIs during the first year after CI activation.

METHOD

Participants included 23 children with simultaneous bilateral CIs, 23 children with bimodal stimulation, and 15 children with unilateral CIs. They all received CIs before 30 months of age. Parents were asked to endorse words that their child could understand only or understand and say using the Early Vocabulary Inventory for Mandarin Chinese at the day of CI activation and 1, 3, 6, 9, and 12 months after CI activation. Receptive and expressive vocabulary sizes were computed.

RESULTS

Growth curve analysis revealed that children with simultaneous bilateral CIs demonstrated faster growth of receptive vocabulary than those with bimodal stimulation, followed by those with unilateral CIs. Moreover, children with simultaneous bilateral CIs reached the 100-word mark for receptive vocabulary earlier than children with bimodal stimulation, followed by those with unilateral CIs. There were no significant differences among the three groups in expressive vocabulary.

CONCLUSIONS

Bilateral CIs have an advantage over bimodal stimulation in early receptive vocabulary development in Mandarin, a tone language. HA usage is still recommended for those who receive one CI.

Pitch Accuracy of Vocal Singing in Deaf Children With Bimodal Hearing and Bilateral Cochlear Implants

OBJECTIVES

The purpose of the present study was to investigate the pitch accuracy of vocal singing in children with severe to profound hearing loss who use bilateral cochlear implants (CIs) or bimodal devices [CI at one ear and hearing aid (HA) at the other] in comparison to similarly-aged children with normal-hearing (NH).

DESIGN

The participants included four groups: (1) 26 children with NH, (2) 13 children with bimodal devices, (3) 31 children with bilateral CIs that were implanted sequentially, and (4) 10 children with bilateral CIs that were implanted simultaneously. All participants were aged between 7 and 11 years old. Each participant was recorded singing a self-chosen song that was familiar to him or her. The fundamental frequencies (F0) of individual sung notes were extracted and normalized to facilitate cross-subject comparisons. Pitch accuracy was quantified using four pitch-based metrics calculated with reference to the target music notes: mean note deviation, contour direction, mean interval deviation, and F0 variance ratio. A one-way ANOVA was used to compare listener-group difference on each pitch metric. A principal component analysis showed that the mean note deviation best accounted for pitch accuracy in vocal singing. A regression analysis examined potential predictors of CI children's singing proficiency using mean note deviation as the dependent variable and demographic and audiological factors as independent variables.

RESULTS

The results revealed significantly poorer performance on all four pitch-based metrics in the three groups of children with CIs in comparison to children with NH. No significant differences were found among the three CI groups. Among the children with CIs, variability in the vocal singing proficiency was large. Within the group of 13 bimodal users, the mean note deviation was significantly correlated with their unaided pure-tone average thresholds (r = 0.582, p = 0.037). The regression analysis for all children with CIs, however, revealed no significant demographic or audiological predictor for their vocal singing performance.

CONCLUSION

Vocal singing performance in children with bilateral CIs or bimodal devices is not significantly different from each other on a group level. Compared to children with NH, the pediatric bimodal and bilateral CI users, in general, demonstrated significant deficits in vocal singing ability. Demographic and audiological factors, known from previous studies to be associated with good speech and language development in prelingually-deafened children with CIs, were not associated with singing accuracy for these children.

Bimodal Stimulation in Children With Bilateral Profound Sensorineural Hearing Loss: A Suitable Intervention Model for Children at the Early Developmental Stage

OBJECTIVE

To evaluate the auditory and speech benefit of bimodal stimulation for prelingual deafened cochlear implantation recipients.

STUDY DESIGN

Retrospective and comparative study.

SETTING

Tertiary referral center.

PATIENTS

Fifty-six children with bilateral prelingual profound sensorineural hearing loss were enrolled, including 28 consecutive children with unilateral cochlear implantation (CI group), and 28 consecutive children with bimodal stimulation (BI group) who used an additional hearing aid (HA) in the contralateral ear.

MAIN OUTCOME MEASURES

Hearing assessments included the Infant-Toddler Meaningful Auditory Integration Scale (IT-MAIS) and Categories of Auditory Performance (CAP). Speech evaluations included the Meaningful Use of Speech Scale (MUSS), and Speech Intelligibility Rating (SIR). These measurements were evaluated at the first mapping of cochlear implants and 0.5, 1, 3, 6, 12, 18, 24 months after. Data were analyzed by repeated measures analysis.

RESULTS

The mean ages of BI and CI groups were similar (17.6 ± 6.87 vs 19.0 ± 8.10 months, p = 0.497). The initial scores for hearing and speech assessments showed no differences between the two groups, apart from IT-MAIS (2.46 ± 0.631 in BI group vs 0.50 ± 0.279 in CI group, p = 0.004). The auditory and speech development over time were different in the two groups as seen in IT-MAIS (p < 0.001), CAP (p = 0.029), MUSS (p < 0.001), and SIR (p < 0.001). A continuing but stable difference was observed in CAP, MUSS, and SIR at 3, 18, and 12 months after the first mapping, respectively. In addition, the BI group had better IT-MAIS scores at 3 and 6 months compared with the CI group; however, the difference was not significant after 12 months.

CONCLUSION

Bimodal stimulation is beneficial for prelingually deafened CI recipients who have minimal contralateral residual hearing when bilateral CIs are not available. Hearing aid use in the contralateral ear might be recommended for children after unilateral cochlear implantation to facilitate the development of auditory and speech skills.

Acoustic features of infant-directed speech to infants with hearing loss

This study investigated the effects of hearing loss and hearing experience on the acoustic features of infant-directed speech (IDS) to infants with hearing loss (HL) compared to controls with normal hearing (NH) matched by either chronological or hearing age (experiment 1) and across development in infants with hearing loss as well as the relation between IDS features and infants' developing lexical abilities (experiment 2). Both experiments included detailed acoustic analyses of mothers' productions of the three corner vowels /a, i, u/ and utterance-level pitch in IDS and in adult-directed speech. Experiment 1 demonstrated that IDS to infants with HL was acoustically more variable than IDS to hearing-age matched infants with NH. Experiment 2 yielded no changes in IDS features over development; however, the results did show a positive relationship between formant distances in mothers' speech and infants' concurrent receptive vocabulary size, as well as between vowel hyperarticulation and infants' expressive vocabulary. These findings suggest that despite infants' HL and thus diminished access to speech input, infants with HL are exposed to IDS with generally similar acoustic qualities as are infants with NH. However, some differences persist, indicating that infants with HL might receive less intelligible speech.

Biomimetic carbon nanotubes for neurological disease therapeutics as inherent medication

Nowadays, nanotechnology is revolutionizing the approaches to different fields from manufacture to health. Carbon nanotubes (CNTs) as promising candidates in nanomedicine have great potentials in developing novel entities for central nervous system pathologies, due to their excellent physicochemical properties and ability to interface with neurons and neuronal circuits. However, most of the studies mainly focused on the drug delivery and bioimaging applications of CNTs, while neglect their application prospects as therapeutic drugs themselves. At present, the relevant reviews are not available yet. Herein we summarized the latest advances on the biomedical and therapeutic applications of CNTs in vitro and in vivo for neurological diseases treatments as inherent therapeutic drugs. The biological mechanisms of CNTs-mediated bio-medical effects and potential toxicity of CNTs were also intensely discussed. It is expected that CNTs will exploit further neurological applications on disease therapy in the near future.

Health-related quality of life in South African children who use cochlear implants

Objective: To describe health-related quality of life (HRQoL) outcomes of school-going paediatric cochlear implant (CI) recipients in a South African cohort from the perspectives of parents.Design: Parents of school-going CI recipients completed the Children with Cochlear Implants: Parental Perspectives (CCIPP) CI-specific HRQoL questionnaire. The effect of different demographic variables on HRQoL outcomes was also determined.Study sample: The study sample included 54 parents of school-going (mean age = 12.2 years; SD = 3.6; range = 6.6-18.3 years) CI recipients with at least six months CI experience.Results: Children's communication and general functioning with a CI received the most positive parental ratings. Among a number of confirmed statistically significant (p < 0.05) associations between HRQoL outcomes and demographic variables, pre-lingual onset of deafness was linked to better HRQoL in terms of general functioning and well-being. While shorter duration of deafness and unilateral implantation were associated with higher parental ratings for self-reliance and well-being respectively, longer duration of CI use was linked to improved HRQoL outcomes in terms of general functioning.Conclusion: Parents assigned positive ratings to their child's HRQoL. This exploration of children's HRQoL related to their CIs contributes to evidence-based paediatric CI services that promote optimal psychosocial outcomes.

Vocal Development in Infants and Toddlers With Bilateral Cochlear Implants and Infants With Normal Hearing

Purpose The purpose of this study was to investigate the time course of vocal development in infants and toddlers with bilateral cochlear implants (CIs; bilateral CI group) who are acquiring Finnish and to compare their progress to that of infants with normal hearing and typical development (TD group). Method Five thousand nine hundred sixty-four spontaneous utterances of 30 infants and toddlers (15 in both groups) were classified as either precanonical (PC) vocalizations, basic canonical syllables (BCS), or advanced forms (AF) levels. Time course of development and group differences were analyzed in a prospective longitudinal study during a time course of 1 year: before implantation and 1, 3, 6, 9, and 12 months after CI activation for the bilateral CI group and at 6, 9, and 12 months of age for the TD group. Results The least mature PC vocalizations decreased and the BCS and AF vocalizations increased for both the bilateral CI and TD groups during the follow-up period of 1 year. The bilateral CI group produced a lower percentage of PC vocalizations (effect size, η_p ² = .35) and a higher percentage of BCS (effect size, η_p ² = .16) and AF vocalizations (effect size, η_p ² = 0.24) than the TD group. Conclusions The findings of this study showed that vocal development of infants and toddlers with early-identified profound hearing loss is delayed before CI activation. Findings also showed that infants and toddlers with bilateral CIs make rapid advancements in vocal development after implantation compared to infants with typical development. However, their vocal development seems to remain delayed at least during the 1st year of bilateral CI use as compared to the well-documented milestones of infants and toddlers with typical development. Information about the vocal development time course following bilateral CI activation helps parents recognize progress in auditory-guided speech development before the emergence and the use of spoken words in communication.

Bilateral cochlear implantation is regarded as very beneficial: results from a worldwide survey by online questionnaire

PURPOSE

Bilateral cochlear implant (CI) provision is now widely regarded as the most beneficial hearing intervention for acceptable candidates. This study sought to determine if a number of well-regarded hearing professionals at highly reputable clinics shared similar practices and beliefs regarding bilateral CI provision, use, and rehabilitation in children and adults.

METHODS

An 11-question online questionnaire was created and distributed to all 27 clinics in the HEARRING group. Questions 1-5 asked for facts; questions 6-11 asked for opinions.

RESULTS

20 completed questionnaires were returned. All 20 respondents reported that their clinics perform bilateral cochlear implantation in children; 18 do so in adults. Regarding the fact-based questions, bilateral CI provision is more commonly performed and more likely to be reimbursed in children than in adults. Children are also much more likely to be implanted simultaneously than are adults. Regarding the opinion-based questions, respondents gave broadly similar answers. Communication between the CIs and speech coding strategies specifically developed for bilateral CI users were regarded as the two future technologies that would most enhance the benefit of bilateral CI use.

CONCLUSIONS

Most clinics in the HEARRING group are very familiar with bilateral CI provision and hold similar opinions on its results and benefits. Hopefully the results described herein will lead to a greater acceptance and regular reimbursement of bilateral CI provision, especially in adults.

Cost-effectiveness of pediatric bilateral cochlear implantation in Spain

OBJECTIVES/HYPOTHESIS

To determine the incremental cost-effectiveness of bilateral versus unilateral cochlear implantation for 1-year-old children suffering from bilateral sensorineural severe to profound hearing loss from the perspective of the Spanish public health system.

STUDY DESIGN

Cost-utility analysis.

METHODS

We conducted a general-population survey to estimate the quality-of-life increase contributed by the second implant. We built a Markov influence diagram and evaluated it for a life-long time horizon with a 3% discount rate in the base case.

RESULTS

The incremental cost-effectiveness ratio of simultaneous bilateral implantation with respect to unilateral implantation for 1-year-old children with severe to profound deafness is €10,323 per quality-adjusted life year (QALY). For sequential bilateral implantation, it rises to €11,733/QALY. Both options are cost-effective for the Spanish health system, whose willingness to pay is estimated at around €30,000/QALY. The probabilistic sensitivity analysis shows that the probability of bilateral implantation being cost-effective reaches 100% for that cost-effectiveness threshold.

CONCLUSIONS

Bilateral implantation is clearly cost-effective for the population considered. If possible, it should be done simultaneously (i.e., in one surgical operation), because it is as safe and effective as sequential implantation, and saves costs for the system and for users and their families. Sequential implantation is also cost-effective for children who have received the first implant recently, but it is difficult to determine when it ceases to be so because of the lack of detailed data. These results are specific for Spain, but the model can easily be adapted to other countries.

LEVEL OF EVIDENCE

2C. Laryngoscope, 127:2866-2872, 2017.

A Longitudinal Study in Children With Sequential Bilateral Cochlear Implants: Time Course for the Second Implanted Ear and Bilateral Performance

PURPOSE

Whether, and if so when, a second-ear cochlear implant should be provided to older, unilaterally implanted children is an ongoing clinical question. This study evaluated rate of speech recognition progress for the second implanted ear and with bilateral cochlear implants in older sequentially implanted children and evaluated localization abilities.

METHOD

A prospective longitudinal study included 24 bilaterally implanted children (mean ear surgeries at 5.11 and 14.25 years). Test intervals were every 3-6 months through 24 months postbilateral. Test conditions were each ear and bilaterally for speech recognition and localization.

RESULTS

Overall, the rate of progress for the second implanted ear was gradual. Improvements in quiet continued through the second year of bilateral use. Improvements in noise were more modest and leveled off during the second year. On all measures, results from the second ear were poorer than the first. Bilateral scores were better than either ear alone for all measures except sentences in quiet and localization.

CONCLUSIONS

Older sequentially implanted children with several years between surgeries may obtain speech understanding in the second implanted ear; however, performance may be limited and rate of progress gradual. Continued contralateral ear hearing aid use and reduced time between surgeries may enhance outcomes.

Predictors of pediatric cochlear implantation outcomes in South Africa

OBJECTIVE

To identify and describe predictors of pediatric cochlear implantation outcomes in a South African population.

METHODS

A retrospective study of 301 pediatric cochlear implant (CI) recipients from five CI programs was conducted and cross-sectional outcome data were added at the time of data collection. Twenty potential prognostic factors were identified from the retrospective dataset, including demographical, CI, risk and family factors. Multiple regression analyses were performed to identify predictor variables that influence outcomes in terms of auditory performance (CAP scores), speech production (SIR scores), communication mode and educational placement.

RESULTS

Although implanted children within this sample did not have equal opportunity to access a second implant, bilateral implantation was strongly predictive of better auditory performance and speech production scores, an oral mode of communication and mainstream education. NICU admittance/prematurity were associated with poorer auditory performance and speech production scores, together with a higher probability for non-oral communication and non-mainstream education. The presence of one or more additional developmental condition was predictive of poorer outcomes in terms of speech production and educational placement, while a delay between diagnosis and implantation of more than one year was also related to non-mainstream education. Ethnicities other than Caucasian were predictive of poorer auditory performance scores and a lower probability for mainstream education.

CONCLUSION

An extensive range of prognostic indicators were identified for pediatric CI outcomes in South Africa. These predictive factors of better and poorer outcomes should guide pediatric CI services to promote optimal outcomes and assist professionals in providing evidence-based informational counseling.

Modification of surface/neuron interfaces for neural cell-type specific responses: a review

Surface/neuron interfaces have played an important role in neural repair including neural prostheses and tissue engineered scaffolds. This comprehensive literature review covers recent studies on the modification of surface/neuron interfaces. These interfaces are identified in cases both where the surfaces of substrates or scaffolds were in direct contact with cells and where the surfaces were modified to facilitate cell adhesion and controlling cell-type specific responses. Different sources of cells for neural repair are described, such as pheochromocytoma neuronal-like cell, neural stem cell (NSC), embryonic stem cell (ESC), mesenchymal stem cell (MSC) and induced pluripotent stem cell (iPS). Commonly modified methods are discussed including patterned surfaces at micro- or nano-scale, surface modification with conducting coatings, and functionalized surfaces with immobilized bioactive molecules. These approaches to control cell-type specific responses have enormous potential implications in neural repair.

As implicações do implante coclear para desenvolvimento das habilidades de linguagem: uma revisão da literatura

Resumo: A reabilitação auditiva por meio do implante coclear tem constituído um campo de atuação e de pesquisa interdisciplinar, cujos interesses têm incidido na investigação das variáveis e processos relacionados às habilidades de linguagem dessa população. O presente estudo teve como objetivo apresentar uma revisão sistemática das pesquisas que investigaram as relações entre o uso do implante coclear e o desenvolvimento da linguagem. Para isso, foi realizada uma busca nas bases científicas Web of Science(r), Scielo(r) e LILACS(r), de 2003 a 2013, de estudos sob escopo da Audiologia (e de áreas correlatas), Educação, Reabilitação e Ciências do Comportamento; aplicando os unitermos "cochlear implant", "auditory recognition", "recognition", "speech", "speech production" e "language". Após um tratamento inicial dos resultados, foram selecionados para análise 86 artigos que foram classificados de acordo com os seguintes critérios: ano de publicação, periódico, área de pesquisa, tipo de estudo, habilidade investigada e a temática. Os resultados indicaram crescente avanço nesses estudos e uma ênfase em avaliar e/ou identificar possíveis fatores que interferem nos processos de linguagem de implantados cocleares, sendo essas pesquisas conduzidas majoritariamente pela Audiologia e áreas correlatas. Os estudos comparativos e explicativos foram os mais frequentes e têm destacado as habilidades auditivas, especificamente os fatores que afetam a percepção auditiva. Enquanto perspectivas futuras, poderão ser vislumbrados maior envolvimento científico de áreas interdisciplinares à Audiologia, ampliação de pesquisas sobre habilidades expressivas (como a produção oral) e fomento à estudos que investiguem intervenções (práticas baseadas em evidências) em linguagem para esse público.

Are Young Children With Cochlear Implants Sensitive to the Statistics of Words in the Ambient Spoken Language?

PURPOSE

The purpose of this study was to determine whether children with cochlear implants (CIs) are sensitive to statistical characteristics of words in the ambient spoken language, whether that sensitivity changes in expected ways as their spoken lexicon grows, and whether that sensitivity varies with unilateral or bilateral implantation.

METHOD

We analyzed archival data collected from the parents of 36 children who received cochlear implantation (20 unilateral, 16 bilateral) before 24 months of age. The parents reported their children's word productions 12 months after implantation using the MacArthur Communicative Development Inventories: Words and Sentences (Fenson et al., 1993). We computed the number of words, out of 292 possible monosyllabic nouns, verbs, and adjectives, that each child was reported to say and calculated the average phonotactic probability, neighborhood density, and word frequency of the reported words.

RESULTS

Spoken vocabulary size positively correlated with average phonotactic probability and negatively correlated with average neighborhood density, but only in children with bilateral CIs.

CONCLUSION

At 12 months postimplantation, children with bilateral CIs demonstrate sensitivity to statistical characteristics of words in the ambient spoken language akin to that reported for children with normal hearing during the early stages of lexical development. Children with unilateral CIs do not.

Academic Outcomes for School-Aged Children With Severe-Profound Hearing Loss and Early Unilateral and Bilateral Cochlear Implants

PURPOSE

This study sought to (a) determine whether academic outcomes for children who received early cochlear implants (CIs) are age appropriate, (b) determine whether bilateral CI use significantly improves academic outcomes, and (c) identify other factors that are predictive of these outcomes.

METHOD

Forty-four 8-year-old children with severe-profound hearing loss participated in this study. Their academic development in mathematics, oral language, reading, and written language was assessed using a standardized test of academic achievement.

RESULTS

(a) Across all academic areas, the proportion of children in the average or above-average ranges was lower than expected for children with normal hearing. The strongest area of performance was written language, and the weakest was mathematics. (b) Children using bilateral CIs achieved significantly higher scores for oral language, math, and written language, after controlling for predictive factors, than did children using unilateral CIs. Younger ages at second CI predicted the largest improvements. (c) High levels of parental involvement and greater time spent by children reading significantly predicted academic success, although other factors were identified.

CONCLUSIONS

Average academic outcomes for these children were below those of children with normal hearing. Having bilateral CIs at younger ages predicted the best outcomes. Family environment was also important to children's academic performance.

Bilateral versus unilateral cochlear implants in children: a study of spoken language outcomes

Objectives:

Although it has been established that bilateral cochlear implants (CIs) offer additional speech perception and localization benefits to many children with severe to profound hearing loss, whether these improved perceptual abilities facilitate significantly better language development has not yet been clearly established. The aims of this study were to compare language abilities of children having unilateral and bilateral CIs to quantify the rate of any improvement in language attributable to bilateral CIs and to document other predictors of language development in children with CIs.

Design:

The receptive vocabulary and language development of 91 children was assessed when they were aged either 5 or 8 years old by using the Peabody Picture Vocabulary Test (fourth edition), and either the Preschool Language Scales (fourth edition) or the Clinical Evaluation of Language Fundamentals (fourth edition), respectively. Cognitive ability, parent involvement in children’s intervention or education programs, and family reading habits were also evaluated. Language outcomes were examined by using linear regression analyses. The influence of elements of parenting style, child characteristics, and family background as predictors of outcomes were examined.

Results:

Children using bilateral CIs achieved significantly better vocabulary outcomes and significantly higher scores on the Core and Expressive Language subscales of the Clinical Evaluation of Language Fundamentals (fourth edition) than did comparable children with unilateral CIs. Scores on the Preschool Language Scales (fourth edition) did not differ significantly between children with unilateral and bilateral CIs. Bilateral CI use was found to predict significantly faster rates of vocabulary and language development than unilateral CI use; the magnitude of this effect was moderated by child age at activation of the bilateral CI. In terms of parenting style, high levels of parental involvement, low amounts of screen time, and more time spent by adults reading to children facilitated significantly better vocabulary and language outcomes. In terms of child characteristics, higher cognitive ability and female sex were predictive of significantly better language outcomes. When family background factors were examined, having tertiary-educated primary caregivers and a family history of hearing loss were significantly predictive of better outcomes. Birth order was also found to have a significant negative effect on both vocabulary and language outcomes, with each older sibling predicting a 5 to 10% decrease in scores.

Conclusions:

Children with bilateral CIs achieved significantly better vocabulary outcomes, and 8-year-old children with bilateral CIs had significantly better language outcomes than did children with unilateral CIs. These improvements were moderated by children’s ages at both first and second CIs. The outcomes were also significantly predicted by a number of factors related to parenting, child characteristics, and family background. Fifty-one percent of the variance in vocabulary outcomes and between 59 to 69% of the variance in language outcomes was predicted by the regression models.

The study compared language abilities of children with unilateral and bilateral cochlear implants (CIs), quantified the rate of language development attributable to bilateral CIs and documented predictors of language development. Children with bilateral CIs achieved significantly better vocabulary outcomes, and 8-year-old children with bilateral CIs had significantly better language outcomes. Improvements were moderated by children’s ages at both first and second CIs. Outcomes were significantly predicted by a number of factors related to parenting, child characteristics, and family background. Fifty-one percent of the variance in vocabulary outcomes and between 59 to 69% of the variance in language outcomes was predicted by the regression models.

Supplemental Digital Content is available in the text.

Results in cochlear implanted children before 5 years of age. a long term follow up

OBJECTIVE

To assess the hearing threshold and linguistic results of cochlear implanted children aged 10 months to 5 years, when they reached the age of 12. We studied the benefits of sequential bilateral implantation.

METHOD AND RESULTS

This is an observational, descriptive, transversal study comprising 57 cochlear implanted subjects. We performed a free field tonal audiometry at 65dB SPL, speech tests and sentences in quiet and noise (SNR+10) tests. The Objective and Criterial Language Battery (BLOC) was used to assess linguistic competence, in its screening version.

RESULTS

Children implanted under the age of 2 and with inter-implant period less than or equal to 4 years reached better statistically significant results in disyllabic and sentences with and without noise (p=0.006) tests and in the disyllabic test with noise (p=0.045) (the hardest speech test). This suggests the acquisition of binaurality, as opposed to children implanted after this age, with inter-implant period longer than 4 years, who do not reach the same performance levels.

RESULTS

of language development in the group implanted at ages 10 months to 2 years are better with respect to implanted children at ages 3-5 (<0.05) in both unilateral and bilateral implanted children in relation to the age of implantation.

CONCLUSION

Children with pre-lingual deafness implanted before the age of 2, when they are 12 years old obtain more benefits in their language development and in their linguistic competence than children implanted after this age. The audiology results are better in children implanted bilaterally under the age of 2.

RAPID ASSESSMENT OF BILATERAL COCHLEAR IMPLANTATION FOR CHILDREN IN KAZAKHSTAN

Objectives:The aim of this study was to evaluate the effectiveness of bilateral cochlear implantation (CI) compared with unilateral CI for deaf children in the context of the Republic of Kazakhstan health system.

Methods.A literature search was conducted, using the PubMed, Cochrane, and Embase data bases for studies that compared the effectiveness of bilateral and unilateral CI in children. The search included English language, publications from 2002–2012. Two reviewers independently evaluated all relevant studies. Administrative data relevant to CI in Kazakhstan were obtained from the Ministry of Health.

Results: Three relevant systematic reviews and an health technology assessment report were found. There was evidence of incremental benefits from bilateral CI but the quality of the available studies was poor and there was little information on longer term outcomes. No conclusions could be drawn regarding later incremental improvements to speech perception, learning, and quality of life. To date, in the Republic of Kazakhstan there is not full coverage of audiological screening due to the lack of medical equipment. This leads to late detection of hearing-impaired children and a long rehabilitation period, requiring more resources. Age of implantation in children is late and only a small minority attend general schools.

Conclusions:The clinical effectiveness of bilateral CI, an expensive health technology, requires further study. Given the current situation in Kazakhstan with audiological screening and access to unilateral CI, there appeared to be other priorities for improving services for children with profound hearing impairment.

Parenting stress in parents of children with cochlear implants: relationships among parent stress, child language, and unilateral versus bilateral implants

Little attention has been focused on stress levels of parents of children with cochlear implants (CIs). This study examined the stress experience of 70 parents of children with CIs by comparing stress levels in this group of parents to those in parents of children without disabilities, identifying primary stressors, examining the relationship between parent stress and child language, and comparing stress in parents of children with bilateral and unilateral CIs. Parents completed a parent stress questionnaire, and the receptive vocabulary and language abilities of the children were evaluated. Results indicated that these parents had a higher incidence of stress than the normative population. Parent stress levels and child language outcomes were negatively correlated. Child behavior and lack of spousal and social support were the prime causes of parent stress. Parents of children with bilateral CIs were significantly less stressed than were parents of children with unilateral CIs.

The effects of sign language on spoken language acquisition in children with hearing loss: a systematic review protocol

BACKGROUND

Permanent childhood hearing loss affects 1 to 3 per 1000 children and frequently disrupts typical spoken language acquisition. Early identification of hearing loss through universal newborn hearing screening and the use of new hearing technologies including cochlear implants make spoken language an option for most children. However, there is no consensus on what constitutes optimal interventions for children when spoken language is the desired outcome. Intervention and educational approaches ranging from oral language only to oral language combined with various forms of sign language have evolved. Parents are therefore faced with important decisions in the first months of their child's life.

METHODS/DESIGN

This article presents the protocol for a systematic review of the effects of using sign language in combination with oral language intervention on spoken language acquisition. Studies addressing early intervention will be selected in which therapy involving oral language intervention and any form of sign language or sign support is used. Comparison groups will include children in early oral language intervention programs without sign support. The primary outcomes of interest to be examined include all measures of auditory, vocabulary, language, speech production, and speech intelligibility skills. We will include randomized controlled trials, controlled clinical trials, and other quasi-experimental designs that include comparator groups as well as prospective and retrospective cohort studies. Case-control, cross-sectional, case series, and case studies will be excluded. Several electronic databases will be searched (for example, MEDLINE, EMBASE, CINAHL, PsycINFO) as well as grey literature and key websites. We anticipate that a narrative synthesis of the evidence will be required. We will carry out meta-analysis for outcomes if clinical similarity, quantity and quality permit quantitative pooling of data. We will conduct subgroup analyses if possible according to severity/type of hearing disorder, age of identification, and type of hearing technology.

DISCUSSION

This review will provide evidence on the effectiveness of using sign language in combination with oral language therapies for developing spoken language in children with hearing loss who are identified at a young age. The information from this review can provide guidance to parents and intervention specialists, inform policy decisions and provide directions for future research.

PROSPERO REGISTRATION NUMBER

CRD42013005426.

Bilateral sequential adult cochlear implantation: who should receive priority in the context of a constrained health care system?

Resource allocation decisions have become increasingly necessary as the cost of health care habitually increases. Bilateral (second side) adult cochlear implantation (CI) is an example of a novel technology with accruing evidence of benefit, yet expense has limited universal employ. Currently at our centers, bilateral implantation is only provided under research protocol. In this article, we discuss the need for a principled approach concerning the distribution of a second device, both during this period of investigation and if ultimately an insured service. Allocation strategies, while extensively addressed in some arenas, have yet to be developed for second-side sequential adult CI. We advocate that physicians must assume an explicit role when both caring for individual patients as well as administering health care programs. We review social justice theories that inform resource allocation macrodecisions, and include a defence of age-based considerations. Our approach to patient selection for adult second-side CI sequentially considers clinical criteria (directly addressed in the article), a willingness to participate in rigorous research, and a 65 year cut-off. Ultimately, we employ random blinded selection for allocating bilateral CI among the remaining similarly situated individuals. This approach functions impartially and in a manner that is transparent for both patient and physician.

Cochlear implantation in nontraditional candidates: preliminary results in adolescents with asymmetric hearing loss

OBJECTIVE

Traditionally, children are cochlear implant (CI) candidates if bilateral severe to profound hearing loss is present and amplification benefit is limited. The current study investigated abilities of adolescents with asymmetric hearing loss (one ear with severe to profound hearing loss and better hearing contralaterally), where the poorer ear received a CI and the better ear maintained amplification.

STUDY DESIGN

Within-subject case study.

SETTING

Pediatric hospital, outpatient clinic.

PATIENTS

Participants were 5 adolescents who had not met traditional CI candidacy because of one better hearing ear but did have 1 ear that met criteria and was implanted. All maintained hearing aid (HA) use in the contralateral ear. In the poorer ear, before implant, 3 participants had used amplification, and the other 2 had no HA experience.

MAIN OUTCOME MEASURE

Participants were assessed in 3 listening conditions: HA alone, CI alone, and both devices together (bimodal) for speech recognition in quiet and noise and sound localization.

RESULTS

Three participants had CI open-set speech recognition and significant bimodal improvement for speech recognition and localization compared with the HA or CI alone. Two participants had no CI speech recognition and limited bimodal improvement.

CONCLUSION

Some adolescents with asymmetric hearing loss who are not typical CI candidates can benefit from a CI in the poorer ear, compared with a HA in the better ear alone. Additional study is needed to determine outcomes for this population, especially those who have early onset profound hearing loss in one ear and limited HA experience.

A case study assessing the auditory and speech development of four children implanted with cochlear implants by the chronological age of 12 months

Children with severe hearing loss most likely receive the greatest benefit from a cochlear implant (CI) when implanted at less than 2 years of age. Children with a hearing loss may also benefit greater from binaural sensory stimulation. Four children who received their first CI under 12 months of age were included in this study. Effects on auditory development were determined using the German LittlEARS Auditory Questionnaire, closed- and open-set monosyllabic word tests, aided free-field, the Mainzer and Göttinger speech discrimination tests, Monosyllabic-Trochee-Polysyllabic (MTP), and Listening Progress Profile (LiP). Speech production and grammar development were evaluated using a German language speech development test (SETK), reception of grammar test (TROG-D) and active vocabulary test (AWST-R). The data showed that children implanted under 12 months of age reached open-set monosyllabic word discrimination at an age of 24 months. LiP results improved over time, and children recognized 100% of words in the MTP test after 12 months. All children performed as well as or better than their hearing peers in speech production and grammar development. SETK showed that the speech development of these children was in general age appropriate. The data suggests that early hearing loss intervention benefits speech and language development and supports the trend towards early cochlear implantation. Furthermore, the data emphasizes the potential benefits associated with bilateral implantation.

Sound localising ability in children with bilateral sequential cochlear implants

OBJECTIVES

To evaluate the sound localisation ability in children with sequential bilateral cochlear implants and the potential influence of age at the time of the first implantation, years of experience with the first implanted ear and the inter-implant interval (time between the first and the second cochlear implantation).

METHODS

Sixty-three prelingually deaf children (mean age, 11.03; range, 6.5-17 years; SD, 3.09) were tested after 12 and 24 months of using bilateral cochlear implants. Every child was tested with each ear alone and both ears together. Five loudspeakers were placed in a 180° horizontal arch with 45° of separation between each loudspeaker. The child was placed 1.5m from the speakers. For each test run, three stimuli were presented at 65dB (A) from each speaker for a total of 15 stimulus presentations. For each test run, we calculated the mean angular error (MAE) and the proportion of correct speakers identified (CSS: correct speaker score). Performance by chance for the MAE was 72° and for the CSS was 20% (1 of 5 speakers).

RESULTS

After 12 months of using bilateral CIs, the added effect of the second CI in the MAE was minor, and there was no significant difference in CSS between listening in the unilateral condition and listening in bilateral condition. After 24 months, however, the added effect of the second CI in the MAE was significant (mean diff=12.2°; 95% CI; 4.5-20.0°, p=0.003). The mean bilateral CSS increased significantly to 38% (diff=7.7%; 95% CI; 1.4-14.0%; p=0.019) while the mean unilateral CSS remained at a similar level (27%). The influence of age at the time of the first implantation on CSS after 24 months was not significant (p=0.96). However, the inter-implant interval showed a significant decrease in score by 1.4% per year between the two implants (p=0.04).

CONCLUSION

Sound localisation with two versus one CI in children with a sequential bilateral cochlear implantation was significantly improved 24 months (but not 12 months) after the second implantation. A shorter inter-implant interval showed a small but significant beneficial effect on sound localisation.

Cochlear implant in the second year of life: lexical and grammatical outcomes

PURPOSE

The authors studied the effect of the cochlear implant (CI) on language comprehension and production in deaf children who had received a CI in the 2nd year of life.

METHOD

The authors evaluated lexical and morphosyntactic skills in comprehension and production in 17 Italian children who are deaf (M = 54 months of age) with a CI and in 2 control groups of children with normal hearing (NH; 1 matched for chronological age and the other whose chronological age corresponded to the duration of CI activation). The authors also compared children with unilateral CI to children with bilateral CI.

RESULTS

Children with CI appeared to keep pace with NH children matched for time since CI activation in terms of language acquisition, and they were similar to same-age NH children in lexical production. However, children with CI showed difficulties in lexical comprehension when a task required phonological discrimination as well as in grammar comprehension and production. Children with bilateral CI showed better comprehension than did children with unilateral CI; the 2 groups were similar for production.

CONCLUSIONS

Activation of CI in the 2nd year of life may provide children who are deaf with a good opportunity to develop language skills, although some limitations in phonological and morphological skills are still present 3 years after auditory reafferentation.

Comparison of bilateral and unilateral cochlear implants in children with sequential surgery

OBJECTIVE

The objective of this study was to evaluate the effect of bilateral versus unilateral cochlear implants and the importance of the inter-implant interval.

METHODS

Seventy-three prelingually deaf children received sequential bilateral cochlear implants. Speech recognition in quiet with the first, second and with both implants simultaneously was evaluated at the time of the second implantation and after 12 and 24 months.

RESULTS

Mean bilateral speech recognition 12 and 24 months after the second implantation was significantly higher than that obtained with either the first or the second implant. The addition of a second implant was demonstrated to have a beneficial effect after both 12 and 24 months. Speech recognition with the second implant increased significantly during the first year. A small, non-significant improvement was observed during the second year. The inter-implant interval significantly influenced speech recognition with the second cochlear implant both at 12 and 24 months, and bilateral speech recognition at 12 months, but not at 24 months.

CONCLUSIONS

A small, but statistically significant improvement in speech recognition was found with bilateral cochlear implants compared with a unilateral implant. A major increase in speech recognition occurred with the second cochlear implant during the first year. A shorter time interval between the two implantations resulted in better speech recognition with the second implant. However, no definitive time-point was found for when the second implant could no longer add a positive effect.

Biotechnology in the treatment of sensorineural hearing loss: foundations and future of hair cell regeneration

PURPOSE

To provide an overview of the methodologies involved in the field of hair cell regeneration. First, the author provides a tutorial on the biotechnological foundations of this field to assist the reader in the comprehension and interpretation of the research involved in hair cell regeneration. Next, the author presents a review of stem cell and gene therapy and provides a critical appraisal of their application to hair cell regeneration. The methodologies used in these approaches are highlighted.

METHOD

The author conducted a narrative review of the fields of cellular, molecular, and developmental biology, tissue engineering, and stem cell and gene therapy using the PubMed database.

RESULTS

The use of biotechnological approaches to the treatment of hearing loss--approaches such as stem cell and gene therapy-has led to new methods of regenerating cochlear hair cells in mammals.

CONCLUSIONS

Incredible strides have been made in assembling important pieces of the puzzle that comprise hair cell regeneration. However, mammalian hair cell regeneration using stem cell and gene therapy are years--if not decades--away from being clinically feasible. If the goals of the biological approaches are met, these therapies may represent future treatments for hearing loss.

Factors predicting functional outcomes of cochlear implants in children

This article reports the relationships between a large number of child- and family-related factors and children's functional outcomes, according to parental report, in the domains of spoken language communication, social skills and participation, academic achievement, and independence and identity, through a series of stepwise regression analyses. Parents of 247 children who had received cochlear implants in three eastern states of Australia completed a survey on their expectations and experiences of their children's outcomes with cochlear implants. A number of the independent variables were found to be associated, either positively or negatively, with children's outcomes. Implications for cochlear implant professionals, early intervention programmes, and educational authorities are discussed.

Adapting to bilateral cochlear implants: early post-operative device use by children receiving sequential or simultaneous implants at or before 3.5 years

OBJECTIVE

To classify adaptation difficulties, or lack thereof, experienced by a clinical population of young bilateral cochlear implant recipients.

METHOD

Forty-six of the first 48 children sequentially or simultaneously implanted at ≤3.5 years at the Melbourne Clinic participated. Classification into categories was based on daily use of both implants at 2 months post-switch-on, with follow-up information obtained at 12 months.

RESULTS

The 37 Category 1 children wore both implants full time at 2 months, and 35 still did so at 12 months. The two Category 2 children used both implants 4 hours daily at 2 months, but achieved full-time use within 12 months. The five Category 3 children used both implants for ≤1 hour, with only three achieving full-time use within 12 months. The two Category 4 children did not use two implants at 2 months, and one still did not wear both implants at 12 months. There were weak/modest but significant relationships between category and each of time between implants and age at bilateral implantation.

DISCUSSION

Ninety-five percent of simultaneously and 70% of sequentially implanted children demonstrated full-time use within 2 months, and nearly all continued to do so at 12 months. Full-time use maximizes opportunities to develop listening skills. Monitoring device use is necessary for all children, especially when significant change occurs. For those experiencing difficulty in adapting, bilateral implant use usually increased over 12 months. Pre-operative counselling must include discussion of possible adaptation difficulties and raise the potential negative influence of age at bilateral implantation and time between implants.

Highly stable carbon nanotube doped poly(3,4-ethylenedioxythiophene) for chronic neural stimulation

The function and longevity of implantable microelectrodes for chronic neural stimulation depends heavily on the electrode materials, which need to present high charge injection capability and high stability. While conducting polymers have been coated on neural microelectrodes and shown promising properties for chronic stimulation, their practical applications have been limited due to unsatisfying stability. Here, poly(3,4-ethylenedioxythiophene) (PEDOT) doped with pure carbon nanotubes (CNTs) was electrochemically deposited on Pt microelectrodes to evaluate its properties for chronic stimulation. The PEDOT/CNT coated microelectrodes demonstrated much lower impedance than the bare Pt, and the PEDOT/CNT film exhibited excellent stability. For both acute and chronic stimulation tests, there is no significant increase in the impedance of the PEDOT/CNT coated microelectrodes, and none of the PEDOT/CNT films show any cracks or delamination, which have been the limitation for many conducting polymer coatings on neural electrodes. The charge injection limit of the Pt microelectrode was significantly increased to 2.5 mC/cm(2) with the PEDOT/CNT coating. Further in vitro experiments also showed that the PEDOT/CNT coatings are non-toxic and support the growth of neurons. It is expected that this highly stable PEDOT/CNT composite may serve as excellent new material for neural electrodes.

Language development in children after receiving bilateral cochlear implants between 5 and 18 months

OBJECTIVE

The objective of this study was to examine receptive and expressive language development in children who received simultaneous bilateral cochlear implants (CIs) between 5 and 18 months of age and to compare the results with language development in chronologically age-matched children with normal hearing.

METHODS

The study used a prospective, longitudinal matched-group design. Data were collected in a clinical setting at postoperative cochlear implant check-ups after 3, 6, 9, 12, 18, 24, 36, and 48 months of implant use. The sample included 42 children: 21 cochlear implant users and 21 with normal hearing, matched pairwise according to gender and chronological age. Communication assessments included the LittlEARS questionnaire, the Mullen Scale of Early Learning, and the Minnesota Child Development Inventory.

RESULTS

The cochlear implant users' hearing function according to LittlEARS was comparable to that of normal-hearing children within 9 months post-implantation. The mean scores after 9 and 12 months were 31 and 33, respectively in the prelingually deaf versus 31 and 34 in the normal-hearing children. The children's receptive and expressive language scores showed that after 12-48 months with cochlear implants, 81% had receptive language skills within the normative range and 57% had expressive language skills within the normative range. The number of children who scored within the normal range increased with increasing CI experience.

CONCLUSIONS

The present study showed that prelingually deaf children's ability to develop complex expressive and receptive spoken language after early bilateral implantation appears promising. The majority of the children developed language skills at a faster pace than their hearing ages would suggest and over time achieved expressive and receptive language skills within the normative range.

Language development in a hearing and a deaf twin with simultaneous bilateral cochlear implants

This case study is an examination of the language development of a single pair of fraternal twins--one with a profound, sensorineural hearing loss who received simultaneous bilateral cochlear implants at 1 year of age and the other with normal hearing. The purpose of the study was to compare the twins' language development over time from 6 months to almost 3 years of age. Findings suggest that early simultaneous bilateral implantation supports the development of age-appropriate language, thus increasing the potential for overall progress commensurate with hearing age peers.