Speech detection and localization results and clinical outcomes for children receiving sequential bilateral cochlear implants before four years of age

Sequential bilateral cochlear implant: long-term speech perception results in children first implanted at an early age

PURPOSE

The study aims to assess the benefit of sequential bilateral cochlear implantation in children with congenital bilateral profound hearing loss, submitted to the first implant at an early age.

METHODS

We enrolled all the bilateral sequential cochlear implanted children who received the first implant within 48 months and the second within 12 years of age at our Institution. The children were submitted to disyllabic word recognition tests and Speech Reception Threshold (SRT) assessment using the OLSA matrix sentence test with the first implanted device (CI1), with the second implanted device (CI2), and with both devices (CIbil). Furthermore, we measured the datalogging of both devices. Then we calculated the binaural SRT gain (b-SRTgain) and checked the correlations between speech perception results and the b-SRTgain with the child's age at CI1 and CI2, DELTA and the datalogging reports.

RESULTS

With the bilateral electric stimulation, we found a significant improvement in disyllabic word recognition scores and in SRT. Moreover, the datalogging showed no significant differences in the time of use of CI1 and CI2. We found significant negative correlations between speech perception abilities with CI2 and age at CI2 and DELTA, and between the SRT with CI1 and the b-SRTgain.

CONCLUSIONS

From this study we can conclude that in a sequential CI procedure, even if a short inter-implant delay and lower ages at the second surgery can lead to better speech perception with CI2, children can benefit from bilateral stimulation independently of age at the second surgery and the DELTA.

An Adaptation and Validation Study of the Speech, Spatial, and Qualities of Hearing Scale (SSQ) in Italian Normal-Hearing Children

This study aimed to translate and adapt the English version of the Speech, Spatial, and Qualities of Hearing Scale (SSQ) for children and for parents into the Italian language; validate SSQ for hearing children and their parents; and evaluate the discriminant validity of the instrument. A group of 102 normal-hearing Italian children, aged between 9 and 16 years, and their parents were included in this study. A group of 31 parents of normal-hearing Italian children aged between 6 and 8 years was also included. A group of 57 hearing-impaired Italian children aged between 9 and 16 years, and their parents were also included, as well as a group of 30 parents of hearing-impaired Italian children aged between 6 and 8 years. Cronbach’s alpha in the SSQ for parents was 0.92; it was 0.95 in the SSQ for children. Guttmann’s split-half coefficient in SSQ for children for both λ4 and λ6 was 0.98; in SSQ for parents in λ4 was 0.96 and λ6 was 0.95. These data provide evidence for the discriminant validity of the SSQ scale (p-value < 0.001). Italian SSQ scales for children and for parents are now available.

Bilateral cochlear implantation versus unilateral cochlear implantation in deaf children: Effects of sentence context and listening conditions on recognition of spoken words in sentences

OBJECTIVES

Previous studies have investigated the efficacy of bilateral cochlear implants (CIs) in deaf children. The current study focused on the use of sentence-context information in different listening conditions to better explain the benefits of bilateral cochlear implantation. We compared the word recognition abilities of children with bilateral CIs and children with unilateral CIs in relation to sentence context and listening conditions. Additionally, we investigated whether sentence context- and listening condition-dependent word recognition scores can differentiate children with bilateral CIs from children with unilateral CIs.

METHODS

Twenty children with bilateral CIs and 20 children with unilateral CIs participated in this study. All children were presented with semantically controlled sentences (high vs. low predictability) in quiet and noisy conditions and were asked to repeat the final words of each sentence.

RESULTS

Children with bilateral CIs had significantly higher word recognition scores than children with unilateral CIs on words embedded in both high- and low-predictability sentences in noisy conditions. The two groups recognized more words in high-predictability sentences than in low-predictability sentences in noisy conditions. The scores on the high-predictability sentences in noisy conditions significantly differentiated children with bilateral CIs from children with unilateral CIs.

CONCLUSION

Bilateral cochlear implantation is more advantageous than unilateral cochlear implantation at the auditory-linguistic processing level in complex listening conditions.

Hearing and speech benefits of cochlear implantation in children: A review of the literature

Cochlear implantation is a safe and reliable treatment for children with severe to profound hearing loss. The primary benefit of these medical devices in children is the acquisition of hearing, which promotes development of spoken language. The present paper reviews published literature demonstrating predictive effects of a number of factors on acquisition of hearing development and speech recognition. Of the many variables that contribute to an individual child's development after implantation, age at implantation, the presence of medical comorbidities, social determinants of health, and the provision of bilateral versus unilateral hearing are those that can vary widely and have consistently shown clear impacts. Specifically, age of implantation is crucial to reduce effects of deafness on the developing auditory system and capture the remarkable plasticity of early development. Language development after cochlear implantation requires therapy emphasizing hearing and oral communication, education, and other support which can be influenced by known social determinants of health; specifically, outcomes in children decline with reductions in socioeconomic status and levels of parental education. Medical co-morbidities also slow rates of progress after cochlear implantation. On the other hand, benefits of implantation increase in children who are provided with access to hearing from both ears. In sum, cochlear implants promote development of hearing in children and the best outcomes are achieved by providing early access to sound in both ears. These benefits can be limited by known social determinants of health which restrict access to needed support and medical comorbidities which add further complexity in care and outcome.

Speech Detection in Noise for Young Bilaterally Implanted Children: Is There Evidence of Binaural Benefit Over the Shadowed Ear Alone?

OBJECTIVES

To measure binaural benefit over the shadowed ear alone for young bilateral cochlear implant (CI) users. It was hypothesized that children who received bilateral CIs at a young age (<4 years), and had significant bilateral experience, would demonstrate lower detection thresholds for speech sounds in background noise in the bilateral CI over the unilateral CI condition when the added CI was ipsilateral to the noise source.

DESIGN

Children receiving bilateral CIs at the Eye and Ear Hospital Clinic in Melbourne were invited to participate in a wider research project evaluating outcomes; those participating in the wider project who were bilaterally implanted by 4 years and were approximately 2 years postoperative were included in the present study. For 20 participants, detection signal to noise ratios (SNRs) were measured for speech presented from in front and noise from 90° in at least 3 of 4 device/noise conditions, namely left CI/noise right and right CI/noise left, plus bilateral CIs/noise right and bilateral CIs/noise left.

RESULTS

As some participants could only complete testing in 3 conditions within the 1 test block, the unilateral versus bilateral comparison was performed for 1 CI (i.e., 1 noise direction) for 15 participants and for both CIs (i.e., noise left and noise right) for 5 participants. Group analysis indicated no significant difference in detection SNR between the unilateral and bilateral CI conditions when adding the left CI or right CI (for the overall group) or when adding the first or second CI (for the 15 participants with sequential bilateral CIs). Separate analyses indicated no significant difference in detection SNR between the unilateral and bilateral CI conditions for the majority of individuals; this occurred irrespective of whether the analysis indicated that the CI added in the bilateral condition was poorer-performing, better-performing, or not significantly different compared with the other CI. Four individuals demonstrated a significant improvement in the bilateral condition when the CI added in the bilateral condition was a better-performing (n = 1), poorer-performing (n = 2), or not significantly different CI (n = 1). There was no relationship between the detection SNR difference between each CI and the detection SNR difference between the unilateral and bilateral conditions.

CONCLUSIONS

The hypothesis of a lower detection SNR in the bilateral condition was not supported by the group results or by the results for the majority of individuals. For the 4 participants who did demonstrate benefit over the shadowed ear alone, that benefit cannot be separated from the potential benefit gained as a result of the CI added in the bilateral condition being the better-performing CI for 1 of the 4. Variation in outcomes could not be related to demographic factors for this group, which was relatively homogeneous for age at bilateral CI and experience; an older, more experienced group may demonstrate greater binaural benefit in these conditions. These results can be used during counseling for families regarding postoperative expectations for young children, especially in the first 2 years.

Sound Localization and Speech Perception in Noise of Pediatric Cochlear Implant Recipients: Bimodal Fitting Versus Bilateral Cochlear Implants

OBJECTIVES

The aim of this study was to compare binaural performance of auditory localization task and speech perception in babble measure between children who use a cochlear implant (CI) in one ear and a hearing aid (HA) in the other (bimodal fitting) and those who use bilateral CIs.

DESIGN

Thirteen children (mean age ± SD = 10 ± 2.9 years) with bilateral CIs and 19 children with bimodal fitting were recruited to participate. Sound localization was assessed using a 13-loudspeaker array in a quiet sound-treated booth. Speakers were placed in an arc from -90° azimuth to +90° azimuth (15° interval) in horizontal plane. To assess the accuracy of sound location identification, we calculated the absolute error in degrees between the target speaker and the response speaker during each trial. The mean absolute error was computed by dividing the sum of absolute errors by the total number of trials. We also calculated the hemifield identification score to reflect the accuracy of right/left discrimination. Speech-in-babble perception was also measured in the sound field using target speech presented from the front speaker. Eight-talker babble was presented in the following four different listening conditions: from the front speaker (0°), from one of the two side speakers (+90° or -90°), from both side speakers (±90°). Speech, spatial, and quality questionnaire was administered.

RESULTS

When the two groups of children were directly compared with each other, there was no significant difference in localization accuracy ability or hemifield identification score under binaural condition. Performance in speech perception test was also similar to each other under most babble conditions. However, when the babble was from the first device side (CI side for children with bimodal stimulation or first CI side for children with bilateral CIs), speech understanding in babble by bilateral CI users was significantly better than that by bimodal listeners. Speech, spatial, and quality scores were comparable with each other between the two groups.

CONCLUSIONS

Overall, the binaural performance was similar to each other between children who are fit with two CIs (CI + CI) and those who use bimodal stimulation (HA + CI) in most conditions. However, the bilateral CI group showed better speech perception than the bimodal CI group when babble was from the first device side (first CI side for bilateral CI users or CI side for bimodal listeners). Therefore, if bimodal performance is significantly below the mean bilateral CI performance on speech perception in babble, these results suggest that a child should be considered to transit from bimodal stimulation to bilateral CIs.

Perceived improvements and challenges following sequential bilateral cochlear implantation in children and adults

OBJECTIVE

Semi-structured interviews were conducted with sequentially implanted bilateral cochlear-implant (biCI) recipients to examine functional aspects of communication that are affected by listening with one versus two CIs.

DESIGN

Participants were 15 adult biCI recipients and parents of 30 children (categorized into three groups by age) with biCIs. All CI users had sequential placement of biCIs with at least six months' experience with the first CI before activation of the second device, and at least three months' experience with both CIs prior to the interview. The parent/paediatric and adult interviews were all conducted by the same examiner. Electronic transcripts of the interview responses were coded for perceived changes or lack thereof in 23 behaviours following biCI. Extent of reported benefit was quantified for each subject within and across these behaviours and at the group level as a function of age.

RESULTS

Most adults and parents of children reported multiple functional changes following biCI use, and changes often translated to enhanced social communication. Nearly all participants were consistent users of biCIs, and were satisfied with their perceived gains in communicating in everyday settings. Most reported ongoing challenges listening in noisy settings. Although many reports on children paralleled those of adults, developmental differences were apparent. Thirteen percent of adults and twenty percent of parents of children in each of the respective groups reported low levels of change.

CONCLUSIONS

Results suggest that many biCI users experience meaningful functional benefits that may be underestimated by traditional outcome measures. We suggest the need to expand measurement approaches to better quantify the nature of these benefits.

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.

The effect of early auditory experience on the spatial listening skills of children with bilateral cochlear implants

OBJECTIVES

Both electrophysiological and behavioural studies suggest that auditory deprivation during the first months and years of life can impair listening skills. Electrophysiological studies indicate that 3½ years may be a critical age for the development of symmetrical cortical responses in children using bilateral cochlear implants. This study aimed to examine the effect of auditory experience during the first 3½ years of life on the behavioural spatial listening abilities of children using bilateral cochlear implants, with reference to normally hearing children. Data collected during research and routine clinical testing were pooled to compare the listening skills of children with bilateral cochlear implants and different periods of auditory deprivation.

METHODS

Children aged 4-17 years with bilateral cochlear implants were classified into three groups. Children born profoundly deaf were in the congenital early bilateral group (received bilateral cochlear implants aged ≤3½ years, n=28) or congenital late bilateral group (received first implant aged ≤3½ years and second aged >3½ years, n=38). Children with some bilateral acoustic hearing until the age of 3½ years, who subsequently became profoundly deaf and received bilateral cochlear implants, were in the acquired/progressive group (n=16). There were 32 children in the normally hearing group. Children completed tests of sound-source localization and spatial release from masking (a measure of the ability to use both ears to understand speech in noise).

RESULTS

The acquired/progressive group localized more accurately than both groups of congenitally deaf children (p<0.05). All three groups of children with cochlear implants showed similar spatial release from masking. The normally hearing group localized more accurately than all groups with bilateral cochlear implants and displayed more spatial release from masking than the congenitally deaf groups on average (p<0.05).

CONCLUSION

Children with bilateral cochlear implants and early experience of acoustic hearing showed more accurate localization skills, on average, than children born profoundly deaf.

Asymmetric Hearing During Development: The Aural Preference Syndrome and Treatment Options

Deafness affects ∼2 in 1000 children and is one of the most common congenital impairments. Permanent hearing loss can be treated by fitting hearing aids. More severe to profound deafness is an indication for cochlear implantation. Although newborn hearing screening programs have increased the identification of asymmetric hearing loss, parents and caregivers of children with single-sided deafness are often hesitant to pursue therapy for the deaf ear. Delayed intervention has consequences for recovery of hearing. It has long been reported that asymmetric hearing loss/single-sided deafness compromises speech and language development and educational outcomes in children. Recent studies in animal models of deafness and in children consistently show evidence of an "aural preference syndrome" in which single-sided deafness in early childhood reorganizes the developing auditory pathways toward the hearing ear, with weaker central representation of the deaf ear. Delayed therapy consequently compromises benefit for the deaf ear, with slow rates of improvement measured over time. Therefore, asymmetric hearing needs early identification and intervention. Providing early effective stimulation in both ears through appropriate fitting of auditory prostheses, including hearing aids and cochlear implants, within a sensitive period in development has a cardinal role for securing the function of the impaired ear and for restoring binaural/spatial hearing. The impacts of asymmetric hearing loss on the developing auditory system and on spoken language development have often been underestimated. Thus, the traditional minimalist approach to clinical management aimed at 1 functional ear should be modified on the basis of current evidence.

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.

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.

Spatial acuity in 2-to-3-year-old children with normal acoustic hearing, unilateral cochlear implants, and bilateral cochlear implants

OBJECTIVES

: To measure spatial acuity on a right-left discrimination task in 2-to-3-year-old children who use a unilateral cochlear implant (UCI) or bilateral cochlear implants (BICIs); to test the hypothesis that BICI users perform significantly better when they use two CIs than when using a single CI, and that they perform better than the children in the UCI group; to determine how well children with CIs perform compared with children who have normal acoustic hearing (NH); to determine the effect of intensity roving on spatial acuity.

DESIGN

: Three groups of children between 26 and 36 months of age participated in this study: 8 children with NH (mean age: 30.9 months), 12 children who use a UCI (mean age: 31.9 months), and 27 children who use BICIs (mean age: 30.7 months). Testing was conducted in a large sound-treated booth with loudspeakers positioned in a horizontal arc with a radius of 1.2 m. The observer-based psychophysical procedure was used to measure the children's ability to identify the hemifield containing the sound source (right versus left). Two methods were used for quantifying spatial acuity, an adaptive-tracking method and a fixed-angle method. In Experiment 1 an adaptive tracking algorithm was used to vary source angle, and the minimum audible angle (MAA), the smallest angle at which right-left discrimination performance is better than chance, was estimated. All three groups participated in Experiment 1. In Experiment 2 source angles were fixed at ±50 degrees, and performance was evaluated by computing the number of SDs above chance. Children in the UCI and BICI groups participated in Experiment 2.

RESULTS

: In Experiment 1, when stimulus intensity was roved by 8 dB, MAA thresholds were 3.3 degrees to 30.2 degrees (mean = 14.5 degrees) and 5.7 degrees to 69.6 degrees (mean = 30.9 degrees) in the NH group and in the BICI group, respectively. When the intensity level was fixed for the BICI group, performance did not improve. Within the BICI group, 5 out of 27 children obtained MAA thresholds within one SD of their peers who have NH; all five had >12 months of bilateral listening experience. In Experiment 2, BICIs provided some advantages when the intensity level was fixed. First, the BICI group outperformed the UCI group. Second, children in the BICI group who repeated the task with their 1st CI alone had statistically significantly better performance when using both devices. In addition, when intensity roving was introduced, a larger percentage of children who had 12 or more months of BICI experience continued to perform above chance than children who had <12 months of BICI experience. Taken together, the results suggest that children with BICIs have spatial acuity that is better than when using their first CI alone and than that of their peers who use UCIs. In addition, longer durations of BICI use tend to result in better performance, although this cannot be generalized to all participants.

CONCLUSION

: This report is consistent with a growing body of evidence that spatial-hearing skills can emerge in young children who use BICIs. The observation that these skills are not concomitantly emerging in age- and experience-matched children who use UCIs suggests that BICIs provide cues that are necessary for these spatial-hearing skills that UCIs do not provide.

Bilateral cochlear implantation in children: localization and hearing in noise benefits

OBJECTIVE

The aim of this study was to report speech performance in quiet and in noise, sound localization with cochlear implanted children bilaterally. Their performances were compared also in unilateral conditions. In addition, speech and language evaluation was analyzed.

METHODS

Twenty-three children implanted with Neurelec Digisonic SP devices in 3 tertiary centres were tested on a battery of speech perception tests in quiet and in noise. Localization was assessed by lateralization tasks (90° and 30°). Progress in speech and language development and subjective assessment of benefit were assessed using several rating scales and questionnaires (categories of auditory perception, speech intelligibility rating, family participating rating scale).

RESULTS

Children scored better when tested in bilateral conditions rather than in unilateral conditions. In quiet, the mean scores for the poorer and better side were 52% and 73%, respectively. In the bilateral condition, the mean score increased to 83%. In noise, the mean scores were 39% and 57% respectively, which increased to a mean of 70% in the bilateral condition. Nine children (<9 years) completed the ±90° lateralization task. For both unilateral conditions performance was not significantly different from chance level. In the bilateral condition, the mean score was 86%. The ±30° lateralization score was completed by eight of the older children (>9 years). The scores in the unilateral conditions were closed to chance level, but significantly better in the bilateral condition (mean of 86%).

CONCLUSIONS

Performances in bilateral conditions were significantly better than in unilateral conditions on speech perception in quiet and in noise. Localization was significantly better when tested in the bilateral condition for ±90° lateralization task for the younger children and the ±30° task for the older children. All these results supported the hypothesis than bilateral cochlear implantation is more beneficial than unilateral implantation in children.

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.

Pediatric cochlear implantation: candidacy evaluation, medical and surgical considerations, and expanding criteria

Since the first cochlear implant approved by the US Food and Drug Administration in the early 1980s, great advances have occurred in cochlear implant technology. With these advances, patient selection, preoperative evaluation, and rehabilitation consideration continue to evolve. This article describes the current practice in pediatric candidacy evaluation, reviews the medical and surgical considerations in pediatric cochlear implantation, and explores the expanding criteria for cochlear implantation within the pediatric population.

Outcomes in cochlear implantation: variables affecting performance in adults and children

This article highlights variables that affect cochlear implant performance, emerging factors warranting consideration, and variables shown not to affect performance. Research on the outcomes following cochlear implantation has identified a wide spectrum of variables known to affect pos0timplantation performance. These variables relate to the device itself as well as individual patient characteristics. Factors believed to affect spiral ganglion cell survival and function have been shown to influence postoperative performance. Binaural hearing affects performance. Social and educational factors also affect postoperative performance. Novel variables capable of affecting performance continue to emerge with increased understanding of auditory pathway development and neural plasticity.

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.

Cochlear implants: current status and future potential

This article reviews the current status of cochlear implantation in both adults and children, including expanding candidacy groups, bilateral implantation, advances in speech processing software, internal and external device hardware, surgical techniques and outcomes. Promising advances, novel therapies and evolving concepts are also highlighted in terms of their future impact on clinical outcomes.

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.

Sound localization skills in children who use bilateral cochlear implants and in children with normal acoustic hearing

OBJECTIVES

To measure sound source localization in children who have sequential bilateral cochlear implants (BICIs); to determine whether localization accuracy correlates with performance on a right-left discrimination task (i.e., spatial acuity); to determine whether there is a measurable bilateral benefit on a sound source identification task (i.e., localization accuracy) by comparing performance under bilateral and unilateral listening conditions; and to determine whether sound source localization continues to improve with longer durations of bilateral experience.

DESIGN

Two groups of children participated in this study: a group of 21 children who received BICIs in sequential procedures (5 to 14 years) and a group of 7 typically developing children with normal acoustic hearing (5 years). Testing was conducted in a large sound-treated booth with loudspeakers positioned on a horizontal arc with a radius of 1.2 m. Children participated in two experiments that assessed spatial hearing skills. Spatial hearing acuity was assessed with a discrimination task in which listeners determined whether a sound source was presented on the right or left side of center; the smallest angle at which performance on this task was reliably above chance is the minimum audible angle. Sound localization accuracy was assessed with a sound source identification task in which children identified the perceived position of the sound source from a multiloudspeaker array (7 or 15); errors are quantified using the root mean square (RMS) error.

RESULTS

Sound localization accuracy was highly variable among the children with BICIs, with RMS errors ranging from 19 to 56 degrees . Performance of the normal hearing group, with RMS errors ranging from 9 to 29 degrees was significantly better. Within the BICI group, in 11 of 21 children, RMS errors were smaller in the bilateral versus unilateral listening condition, indicating bilateral benefit. There was a significant correlation between spatial acuity and sound localization accuracy (R = 0.68, p < 0.01), suggesting that children who achieve small RMS errors tend to have the smallest minimum audible angles. Although there was large intersubject variability, testing of 11 children in the BICI group at two sequential visits revealed a subset of children who show improvement in spatial hearing skills over time.

CONCLUSIONS

A subset of children who use sequential BICIs can acquire sound localization abilities, even after long intervals between activation of hearing in the first- and second-implanted ears. This suggests that children with activation of the second implant later in life may be capable of developing spatial hearing abilities. The large variability in performance among the children with BICIs suggests that maturation of sound localization abilities in children with BICIs may be dependent on various individual subject factors such as age of implantation and chronological age.

Can adolescents and young adults with prelingual hearing loss benefit from a second, sequential cochlear implant?

This study aimed to determine if adolescents/young adults gained additional perceptual benefit from sequential bilateral cochlear implants within 12 months, and to document adaptation to the second implant. Assessments comprised a pediatric version of The Speech, Spatial and Qualities of Hearing Scale (SSQ), anecdotal reports of device use and daily listening, and the Adaptive Spondee Discrimination Test (AdSpon). All nine participants achieved full-time use of, a preference for, and superior daily listening with, bilateral implants. Eight participants were comfortable using the second implant alone, and two achieved similar daily listening with either implant alone. SSQ ratings were higher post-operatively for the majority of participants. AdSpon performance was superior bilaterally for five participants with noise ipsilateral to the first implant, but not contralateral. Unilateral performance with either implant was similar for one participant. A second implant may provide additional benefit up to 19 years of age, even with congenital hearing loss and >16 years between implants. Families and clinicians should understand the aspects of second-implant candidacy and post-operative use that are unique to adolescents/young adults.

Bilateral versus unilateral cochlear implantation in young children

OBJECTIVES

To compare the preverbal communication skills of two groups of young implanted children: those with unilateral implantation and those with bilateral implantation.

MATERIAL AND METHODS

The study assessed 69 children: 42 unilaterally and 27 bilaterally implanted with age at implantation less than 3 years. The preverbal skills of these children were measured before and 1 year after implantation, using Tait Video Analysis that has been found able to predict later speech outcomes in young implanted children.

RESULTS

Before implantation there was no significant difference between the unilateral group and the bilateral group. There was still no difference at 12 months following implantation where vocal autonomy is concerned, but a strongly significant difference between the groups for vocal turn-taking and non-looking vocal turns, the bilateral group outperforming the unilateral group. Regarding gestural turn-taking and gestural autonomy, there was a strongly significant difference between the two groups at the 12 month interval, and also a difference before implantation for gestural autonomy, the unilateral group having the higher scores. Multiple regression of non-looking vocal turns revealed that 1 year following implantation, bilateral implantation contributed to 51% of the variance (p<0.0001), after controlling for the influence of age at implantation and length of deafness which did not reach statistical significance.

CONCLUSIONS

Profoundly deaf bilaterally implanted children are significantly more likely to use vocalisation to communicate, and to use audition when interacting vocally with an adult, compared with unilaterally implanted children. These results are independent of age at implantation and length of deafness.

Functional outcome of sequential bilateral cochlear implantation in young children: 36 months postoperative results

OBJECTIVE

To examine the effects of sequential bilateral cochlear implantation (CI) on the life of young children after 36 months of bilateral implant use.

METHOD

Thirty-five children were assessed prior to and 3 until 36 months after activation of the second CI. Main outcome measures were: the Categories of Auditory Performance (CAP), Speech Intelligibility Rating (SIR), communication mode, classroom placement, parent reports and the Würzburg questionnaire. Results were analysed separately for children younger and older than 6 years at the time of the second implantation.

RESULTS

At the 3-year test interval, 80% of the younger children attended mainstream schools and were comprehensible for all listeners. They all used oral communication and almost 70% of them could have a conversation over the telephone. After 3 years of bilateral implant use less than 50% of the older children obtained the highest score on the SIR and CAP. Approximately 70% of them was integrated in mainstream schools and used oral communication. All parents reported a more natural communication and an improved quality of life.

CONCLUSIONS

Sequential bilateral implantation seems to offer a wide range of participation benefits to all children and facilitates the social intercourse with their hearing environment.