Bilateral cochlear implants: a way to optimize auditory perception abilities in deaf children?

Similar performance in sound localisation with unsynchronised and synchronised automatic gain controls in bilateral cochlear implant recipients

OBJECTIVE

One proposed method to improve sound localisation for bilateral cochlear implant (BiCI) users is to synchronise the automatic gain control (AGC) of both audio processors. In this study we tested whether AGC synchronisation in a dual-loop front-end processing scheme with a 3:1 compression ratio improves sound localisation acuity.

DESIGN

Source identification in the frontal hemifield was tested in in an anechoic chamber as a function of (roving) presentation level. Three different methods of AGC synchronisation were compared to the standard unsynchronised approach. Both root mean square error (RMSE) and signed bias were calculated to evaluate sound localisation in the horizontal plane.

STUDY SAMPLE

Six BiCI users.

RESULTS

None of the three AGC synchronisation methods yielded significant improvements in either localisation error or bias, neither across presentation levels nor for individual presentation levels. For synchronised AGC, the pooled mean (standard deviation) localisation error of the three synchronisation methods was 24.7 (5.8) degrees RMSE, for unsynchronised AGC it was 27.4 (7.5) degrees. The localisation bias was 5.1 (5.5) degrees for synchronised AGC and 5.0 (3.8) for unsynchronised.

CONCLUSIONS

These findings do not support the hypothesis that the tested AGC synchronisation configurations improves localisation acuity in bilateral users of MED-EL cochlear implants.

Impact of ASL Exposure on Spoken Phonemic Discrimination in Adult CI Users: A Functional Near-Infrared Spectroscopy Study

We examined the impact of exposure to a signed language (American Sign Language, or ASL) at different ages on the neural systems that support spoken language phonemic discrimination in deaf individuals with cochlear implants (CIs). Deaf CI users (N = 18, age = 18-24 yrs) who were exposed to a signed language at different ages and hearing individuals (N = 18, age = 18-21 yrs) completed a phonemic discrimination task in a spoken native (English) and non-native (Hindi) language while undergoing functional near-infrared spectroscopy neuroimaging. Behaviorally, deaf CI users who received a CI early versus later in life showed better English phonemic discrimination, albeit phonemic discrimination was poor relative to hearing individuals. Importantly, the age of exposure to ASL was not related to phonemic discrimination. Neurally, early-life language exposure, irrespective of modality, was associated with greater neural activation of left-hemisphere language areas critically involved in phonological processing during the phonemic discrimination task in deaf CI users. In particular, early exposure to ASL was associated with increased activation in the left hemisphere's classic language regions for native versus non-native language phonemic contrasts for deaf CI users who received a CI later in life. For deaf CI users who received a CI early in life, the age of exposure to ASL was not related to neural activation during phonemic discrimination. Together, the findings suggest that early signed language exposure does not negatively impact spoken language processing in deaf CI users, but may instead potentially offset the negative effects of language deprivation that deaf children without any signed language exposure experience prior to implantation. This empirical evidence aligns with and lends support to recent perspectives regarding the impact of ASL exposure in the context of CI usage.

Comparison of Outcomes in Unilateral and Bilateral Pediatric Cochlear Implants: Our Experience

The aim of our study is to compare the outcomes in unilateral and bilateral cochlear implants in pediatric age and also between simultaneous and sequential cochlear implant surgery. This retrospective study was carried out with 83 children aged between 12 months to 2.5 years which included 41 children with bilateral Cochlear implants and 42 with unilateral implants. Out of these 41 children, 21 were simultaneous and 20 were sequential cochlear implant. All the children were operated at civil hospital Gandhinagar, Gujarat, India. CAP, SIR, localization, traffic noise and speech in noise scores were assessed at regular intervals over the period of 4 years. Also the drug administration time, surgical time, operating room time were assessed for simultaneous and sequential cochlear implant surgery. Children with bilateral simultaneous implants fared significantly better with CAP, SIR, localization, speech noise and traffic noise scores than sequential bilateral implants and unilateral implants with a significant difference of means t tests between the two groups. Simultaneous cochlear implant surgery is associated with reduced surgical time, operating room time, it shortens the total in patient stay. There is less of drug administration and bilateral ones are stimulated simultaneously. Bilateral cochlear implants perform better with respect to auditory perception skills and spontaneous speech when compared with unilateral implants, but simultaneous surgery is better and safe option for pediatric cochlear implantation.

Cochlear Implantation in Young Mandarin-Speaking Children: One Year After First Fitting

INTRODUCTION

Bilateral cochlear implantation has been shown to be beneficial in terms of sound localization and speech recognition in children with congenital deafness. However, little is known about the benefits of bilateral cochlear implantationin children who communicate in a tonal language such as Mandarin. This study aims to investigate the auditory perception and speech intelligibility of Mandarin-speaking children 1 year after first fitting.

MATERIALS AND METHODS

Twenty-nine children aged between 11.5 and 17.9 months with severe-to-profound bilateral sensorineural hearing loss were recruited; 10 were unilaterally implanted and 19 were bilaterally implanted. A test battery was used to monitor improvements during the first year of cochlear implant use.

RESULTS

Bilaterally implanted children scored better in the spatial domain of the Speech, Spatial and Qualities of hearing scale for Parents (SSQ-P) in comparison to unilaterally implanted children. Significant improvements were observed in auditory performance and speech intelligibility at 6 and 12 months after first fitting for both groups of children.

DISCUSSION

Young children that speak a tonal language, such as Mandarin, can obtain significant improvements in hearing and speech abilities within the first year of cochlear implant use. Furthermore, bilateral implantation provides users with better spatial hearing in comparison to unilateral implantation.

The Importance of Access to Bilateral Hearing through Cochlear Implants in Children

Children with hearing loss require early access to sound in both ears to support their development. In this article, we describe barriers to providing bilateral hearing and developmental consequences of delays during early sensitive periods. Barriers include late identification of hearing loss in one or both ears and delayed access to intervention with hearing devices such as cochlear implants. Effects of delayed bilateral input on the auditory pathways and brain are discussed as well as behavioral effects on speech perception and other developmental outcomes including language and academics. Evidence for these effects has supported an evolution in cochlear implant candidacy in children that was started with unilateral implantation in children with profound deafness bilaterally to bilateral implantation to implantation of children with asymmetric hearing loss including children with single-side deafness. Opportunities to enhance the developmental benefits of bilateral hearing in children with hearing loss are also discussed including efforts to improve binaural/spatial hearing and consideration of concurrent vestibular deficits which are common in children with hearing loss.

Bilateral Cochlear Implantation in Children: Long-Term Outcome in the Adult Population With Special Emphasis on the Bilateral Benefit

OBJECTIVE

To investigate the benefit of bilateral cochlear implantation in adults, who had been implanted being a child under the age of 10 years.

STUDY DESIGN

Retrospective data analysis.

SETTING

Tertiary referral center with a large cochlear implant program.

MAIN OUTCOME MEASURES

Speech understanding in the Freiburg monosyllabic words in quiet and the HSM sentence test in quiet and in background noise.

PATIENTS

Seventy-seven bilaterally cochlear implantation implanted adults.

RESULTS

Bilateral cochlear implantation in children under the age of 10 years results in a significant benefit in speech comprehension in adulthood. In addition, a dependency regarding the time between the implantations and speech intelligibility was found.

CONCLUSION

The results emphasize the benefit of bilateral cochlear implantation with a short interval between the operations in young children not only during formative years but also in adulthood.

Bilateral cochlear implantation

Binaural hearing has certain benefits while listening in noisy environments. It provides the listeners with access to time, level and spectral differences between sound signals, perceived by the two ears. However, single sided deaf (SSD) or unilateral cochlear implant (CI) users cannot experience these binaural benefits due to the acoustic input coming from a single ear. The translational research on bilateral CIs started in the year 1998, initiated by J. Müller and J. Helms from Würzburg, Germany in association with MED-EL. Since then, several clinical studies were conducted by different research groups from across the world either independently or in collaboration with MED-EL. As a result, the bilateral CI has become the standard of care in many countries along with reimbursement by the health care systems. Recent data shows that children particularly, are given high priority for the bilateral CI implantation, most often performed simultaneously in a single surgery, as the binaural hearing has a positive effect on their language development. This article covers the milestones of translational research from the first concept to the widespread clinical use of bilateral CI.

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.

Comparison of Speech Performance in Bimodal versus Bilateral Cochlear Implant Users

OBJECTIVE

To assess whether listening with two cochlear implants (bilateral) offers significant benefits in terms of speech perception over listening with one cochlear implant and one hearing aid (bimodal).

METHODS

Retrospective review of bilateral cochlear implant recipients (24 pediatric and 26 adult). Bimodal listening was compared to bilateral listening in terms of speech perception performance at 1-year post second implant under three listening conditions: 50 dBHL, 35 dBHL, and 50 dBHL+5 SNR. Changes in speech performance from bimodal (before second implant) to bilateral (after second implant) listening were determined within subjects and compared to a separate control group of bimodal users matched for age of first implantation who never received a second implant (10 pediatric and 20 adult).

RESULTS

In the pediatric group, compared to bimodal listening prior to a second implant, speech perception scores with bilateral implants increased significantly when measured at 50 dBHL, 35 dBHL, and 50 dBHL+5 SNR. By contrast, pediatric bimodal controls who never received a second implant failed to demonstrate similar improvement over 1 year's time. In the adult group, compared to bimodal listening prior to a second implant, speech perception scores with bilateral implants increased when measured at 50 dBHL, but were not significantly different at 35 dBHL and 50 dBHL + 5 SNR. Adult bimodal controls who never received a second implant failed to demonstrate significant improvement in all conditions over 1 year's time.

CONCLUSION

Bilateral listening with two cochlear implants improved speech perception performance relative to bimodal listening in the pediatric population. Improvement in the adult population was not as significant.

LEVEL OF EVIDENCE

4, Retrospective Chart Review. Laryngoscope, 131:E1322-E1327, 2021.

[Sequential bilateral cochlear implantation with long interval between surgeries in deaf-blind patient]

The efficacy of sequential bilateral cochlear implantation with long interval between surgeries (18 years) was investigated in deaf-blind patient (22 years old man, lost hearing and vision after meningitis at the age 2.5 years). At the age 4 years he got cochlear implant at right ear. His speech skills completely disappeared before the implantation. Auditory-speech rehabilitation with cochlear implant was successful - patient has good auditory, language, speech, cognitive skills. At the age 22 years patient made decision to get cochlear implant at the left ear after breakdown of internal part of cochlear implant at right ear in spite of successful reoperation. After activation of new processor (all electrodes were activated) the patient got daily auditory training with cochlear implant at left ear (Concerto/Opus 2, Medel) on the base of 'auditory' method, in daily life patient uses 2 devices. After 1 month of using cochlear implant at left ear the patient recognized environmental sounds and music instruments, words and sentences in close set tests EARS battery, the score for OLSA test in quiet was 90%, but the perception in noise was complicated. The balance of parameters of fitting for 1-st and 2-nd processors and special auditory training with two cochlear implants provided the development of initial binaural interaction. Perilinqually deaf patients can achieve high effect after sequential bilateral cochlear implantation with long interval between surgeries. The necessary conditions are - preservation of electrical activity of auditory nerve, intensive structured auditory training with new 'ear', patient's motivation of using of cochlear implant at 'new' ear.

Categories of Auditory Performance and Speech Intelligibility Ratings in Prelingually Deaf Children With Bilateral Implantation

Purpose The aim of the current study was to review all pediatric cases with congenital deafness who underwent bilateral implantation in our center. Specifically, auditory performance and speech intelligibility ratings were compared across children based on their mode of bilateral stimulation (simultaneous or sequential implantation). Method A retrospective chart review design was used in this study. A total of 46 congenitally deaf children were included. Children ranged in age between 2 and 8 years, with a mean of 3 years 7 months. Participants were divided into 2 groups: those who received their bilateral implant simultaneously and those who received them sequentially. Categories of Auditory Performance (CAP; Archbold, Lutman, & Marshall, 1995 ) scores and Speech Intelligibility Rating (SIR; M. C. Allen, Nikolopoulos, & O'Donoghue, 1998 ) scores were used to measure their performance. Results Children scored an average of 4.1 (±1.6) on the CAP Scale and 1.6 (±1) on the SIR Scale. Results showed that children who received their implants simultaneously scored relatively higher on the CAP Scale than those with sequential implants. However, there were no differences between the 2 groups in SIR scores. These 2 outcome measures were not correlated with age at implantation. Conclusion The current study demonstrated that simultaneous implantation could potentially improve audiologic outcome.

Early auditory skills development in Mandarin speaking children after bilateral cochlear implantation

OBJECTIVES

The purpose of the present study was: (1) to investigate the early auditory preverbal behaviors of infants/toddlers with bilateral cochlear implants (BCI), and to compare their performance with that of unilateral cochlear implant (UCI) peers; (2) to investigate effects of age of implantation, education level of caregivers, living environment, and unaided behavioral threshold before operation on early auditory preverbal development.

METHODS

The evaluation material of the present study was the Mandarin version of the LittlEARS^® Auditory Questionnaire (LEAQ). Assessments were administrated at 0, 1, 2, 3, 6, 9, 12 and 24 months after cochlear implants (CIs) were switched on. A one-way ANOVA was used to analyze the differences of early auditory preverbal performance between each two contiguous test intervals. A two-sample t-test was used to analyze the difference of behaviors between infants/toddlers with BCI and UCI. Non-parametric tests were used to analyze the effects of potential affecting factors on auditory preverbal skills.

RESULTS

Nineteen subjects aging from 9 to 54 months (Mean = 22.7, SD = 13.7) were recruited in the study. At each evaluation time, the average scores of LEAQ were 4.58, 9.00, 16.00, 18.56, 22.00, 31.50, 29.67, and 34.35 respectively. The total score and semantic auditory behavior score increased significantly during the second months after CIs activation (the total score: LSD-t = 3.157, p = 0.030; semantic auditory behavior score: LSD-t = 1.972, p = 0.034). The score of BCI group was significantly higher than UCI group after 1, 3 and 6 months of CI use (1 month: t = 3.257, p = 0.002; 3 months: t = 5.042, p = 0.000; 6 months: t = 4.054, p = 0.000). Education level of caregivers had a positive effect on receptive auditory behavior (H = 6.538, p = 0.035) after CIs switched on for 3 months. The LEAQ performance was not significantly correlated with pre-operative behavioral threshold although they showed a trend of negative correlation in the first 3 months after activation.

CONCLUSION

The study indicated that infants and toddlers who underwent BCI had better auditory preverbal skills than their UCI peers. Higher caregivers' education level positively correlated with the early development of auditory preverbal skills. Better pre-operative behavioral threshold might also benefit early auditory preverbal skills development for BCI children.

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.

Sequential pediatric bilateral cochlear implantation: The effect of time interval between implants

OBJECTIVE

To examine speech intelligibility in children subjected to sequential bilateral cochlear implants (CI) surgery and to assess the influence of the inter-stage interval duration.

INTRODUCTION

Binaural hearing recovery can have additional benefits, especially in speech and language development in patients with congenital profound sensorineural hearing loss; so recently there has been an increase in the number of children receiving bilateral CI.

METHODS

Twenty-seven children who underwent sequential bilateral cochlear implant (SBCI) with a short (1-3 yrs), medium (4-6 yrs) and long (7-12 yrs) range interval between both implantations, respectively, were evaluated. All patients underwent periodic speech perception test in quiet and noise after second implant activation in three conditions: with the first or second implant alone and with both implants. Results were examined according to the inter-stage interval.

RESULTS

Speech intelligibility in noise was significantly better under bilateral conditions than either ear alone, in all three groups. Small improvements were seen in quiet, especially in the third group (6-12 yrs).

CONCLUSION

Benefits of second implant in the early-implanted children and after a short inter-implant delay are more evident. However our study support that, even after a long period of deafness and despite a prolonged inter-stage interval, sequential bilateral cochlear implantation should be considered.

LEVEL OF EVIDENCE

Level 4.

The effects of early auditory-based intervention on adult bilateral cochlear implant outcomes

OBJECTIVES

The goal of this exploratory study was to determine the types of improvement that sequentially implanted auditory-verbal and auditory-oral adults with prelingual and childhood hearing loss received in bilateral listening conditions, compared to their best unilateral listening condition.

METHODS

Five auditory-verbal adults and five auditory-oral adults were recruited for this study. Participants were seated in the center of a 6-loudspeaker array. BKB-SIN sentences were presented from 0° azimuth, while multi-talker babble was presented from various loudspeakers. BKB-SIN scores in bilateral and the best unilateral listening conditions were compared to determine the amount of improvement gained.

RESULTS

As a group, the participants had improved speech understanding scores in the bilateral listening condition. Although not statistically significant, the auditory-verbal group tended to have greater speech understanding with greater levels of competing background noise, compared to the auditory-oral participants.

DISCUSSION

Bilateral cochlear implantation provides individuals with prelingual and childhood hearing loss with improved speech understanding in noise. A higher emphasis on auditory development during the critical language development years may add to increased speech understanding in adulthood. However, other demographic factors such as age or device characteristics must also be considered.

CONCLUSION

Although both auditory-verbal and auditory-oral approaches emphasize spoken language development, they emphasize auditory development to different degrees. This may affect cochlear implant (CI) outcomes. Further consideration should be made in future auditory research to determine whether these differences contribute to performance outcomes. Additional investigation with a larger participant pool, controlled for effects of age and CI devices and processing strategies, would be necessary to determine whether language learning approaches are associated with different levels of speech understanding performance.

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 experience of bilateral cochlear implantation in a child with LEOPARD syndrome

We present a 3-year old boy with Leopard syndrome. His clinical manifestations included a congenital bilateral sensorineural hearing loss. He underwent cochlear implantation on the right side at age 1 year and on the left side at age 1.5 years. The patient is doing very well and mainstreamed in a regular pre-school program with a teacher of the deaf and home based speech therapy. Bilateral cochlear implantation in the case of a child with Leopard syndrome can be successful.

Criteria for Selecting an Optimal Device for the Contralateral Ear of Children with a Unilateral Cochlear Implant

OBJECTIVE

To identify clinical criteria for selecting the aiding device for the contralateral ear of children with a unilateral cochlear implant (CI).

METHODS

Sixty-five children, including 36 bilateral CI users and 29 bimodal users, participated in the study. A speech perception test (monosyllabic word test) in noise was administered. The target speech (65 dB sound pressure level) was presented from the front loudspeaker, and noise (10 dB signal-to-noise ratio) was presented from 3 directions: from in front of the child and 90° to the child's right and left sides. The test was performed using the first CI alone and under bilateral CI or bimodal conditions. The bilateral benefits to speech perception in noise were compared between bilateral CI users and bimodal users.

RESULTS

Significant benefits in speech perception in noise were evident in bilateral CI users in all 3 noise conditions. In bimodal users, the hearing threshold at low frequencies of ≤1 kHz in the nonimplanted ear affected the bilateral benefit. Bimodal users with a low-frequency hearing threshold ≤90 dB hearing level (HL) showed a significant bilateral benefit in various noise conditions. By contrast, bimodal users with a low-frequency hearing threshold >90 dB HL showed no significant bilateral benefits in all 3 noise conditions.

CONCLUSIONS

Bilateral CI and bimodal listening provide better speech perception in noise than unilateral CI alone in children. The contralateral CI is better than bimodal listening for children with a low-frequency hearing threshold >90 dB HL. A hearing threshold at low frequencies of ≤1 kHz may be a good criterion for deciding on the type of device for the contralateral ear of children with a unilateral CI.

Tone and sentence perception in young Mandarin-speaking children with cochlear implants

OBJECTIVES

The purpose of this study was to examine the outcomes of cochlear implantation in young children in terms of (1) perception of lexical tones in quiet, (2) perception of sentences in quiet and in noise, (3) the effects of five demographic variables (i.e., preoperative hearing level, age at implantation, duration of cochlear implants use, maternal educational level, and whether a child underwent a hearing aid trial before implantation) on lexical tone perception and sentence perception, and (4) the relationship between lexical tone perception and sentence perception.

METHODS

96 participants, aged from 2.41 years to 7.09 years, were recruited in mainland China. The children exhibited normal cognitive abilities and received unilateral implants at an average age of 2.72 years, with ages ranging from 0.69 to 5 years of age.

RESULTS

The mean score for tone identification was 77% (SD=13%; chance level=50%). Tone 2/tone 3 was the most difficult tone contrast to identify. Children with a longer duration of CI use and whose mothers had more years of education tended to perform better in sentence perception in quiet and in noise. Having undergone a hearing aid trial before implantation and more residual hearing were additional factors contributing to better sentence perception in noise. The only demographical variable that related to tone perception in quiet was duration of CI. In addition, while there was a modest correlation between tone perception and sentence perception in quiet (rs=0.47, p<0.001), the correlation between tone perception in quiet and sentence perception in noise was much weaker (rs=-0.28, p<0.05).

CONCLUSIONS

The findings suggested that most young children who had been implanted before 5 years of age and had 1-3 years of implant use did not catch up with their aged peers with normal hearing in tone perception and sentence perception. The weak to moderate correlation between tone perception in quiet and sentence perception might imply that the improvement of tone perception in quiet may not necessarily contribute to sentence perception, especially in noise condition.

Accessibility to cochlear implants in Belgium: state of the art on selection, reimbursement, habilitation, and outcomes in children and adults

Belgium, and especially the northern region called Flanders, has been a center of expertise in cochlear implants and early hearing screening for many years. Some of their surgeons and engineers were pioneers in the development of cochlear implants and in 1998 Flanders was the first region in Europe to implement a universal hearing screening program for all neonates. The Belgian National Institute for Health and Disability Insurance has reimbursed cochlear implants in children and adults since 1994 and bilateral implantation in children under the age of 12 years since February 2010. These deaf children, screened and implanted early, achieve higher auditory, speech and language outcomes and increasing numbers are going to regular schools using fewer interpreters. In 2010, 93% of severe-to-profound deaf preschool children in Flanders had received cochlear implants and 25% had bilateral implants. Although on average twice as many adults as children are implanted a year in Belgium, we have less research data available from this adult population. Also very little is published about the growth curves and minimal rehabilitation requirements (intensity, duration etc.) after implantation for both children and adults. So, there still remain many challenges for the future.

Environment-adaptive speech enhancement for bilateral cochlear implants using a single processor

A computationally efficient speech enhancement pipeline in noisy environments based on a single-processor implementation is developed for utilization in bilateral cochlear implant systems. A two-channel joint objective function is defined and a closed form solution is obtained based on the weighted-Euclidean distortion measure. The computational efficiency and no need for synchronization aspects of this pipeline make it a suitable solution for real-time deployment. A speech quality measure is used to show its effectiveness in six different noisy environments as compared to a similar one-channel enhancement pipeline when using two separate processors or when using independent sequential processing.

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.

Functional benefits of sequential bilateral cochlear implantation in children with long inter-stage interval between two implants

OBJECTIVES

Older children are increasingly deriving binaural benefits from sequential bilateral cochlear implantation, and this procedure should be considered by experienced cochlear implant centers. This study aimed to identify the influence of a long inter-stage interval between two implants in older children. Speech perception and everyday listening performance were investigated and analyzed according to the length of the inter-stage interval.

STUDY DESIGN AND SETTINGS

Forty-two children who received sequential bilateral cochlear implantation participated in this study. Their average ages at the first and second implantation were 4.2 and 9.7 years, respectively. All subjects acquired excellent speech performance from their first implant, and the mean inter-stage interval was 5.5 years. Speech perception in quiet was assessed by formal speech measures, and postoperative performance using the second implant only was compared with the preoperative performance. Speech perception in noise test was administered using three noise directions with noise (+10 dB signal-to-noise ratio) from front and 90° to each side, and the change in performance using the first implant only and both implants were analyzed across the three noise directions. Subjects were divided into three groups according to their inter-stage interval (group I, 3-4.9 years; group II, 5-6.9 years; and group III, 7-9.9 years), and the test results were compared between the groups. Functional hearing benefits in daily life were measured by a questionnaire before and after bilateral cochlear implantation.

RESULTS

The speech perception abilities in quiet using the second implant only improved quickly and were similar to those using the first implant only within 1 year after the second implantation. The scores for the monosyllabic word test (phoneme: p=0.052; word: p=0.125) and common phrases sentence test (p=0.062) 6 month after the second implantation, and the Categories of Auditory Performance score (p=1.000) 1 year after the second implantation using the second implant only did not differ significantly from those using the first implant only. Speech perception was significantly better using both implants than using the first implant in all three noise conditions (speech and noise in front: p=0.004; speech in front and noise to the first implant: p=0.003; speech in front and noise to the second implant: p<0.001), and the effect of noise direction was negligibly small. No salient influence of inter-stage interval was observed in both quiet and noise tests. The second and third groups with longer inter-stage intervals (>5 years) achieved performance close to the level of the first group with a shorter interval. These subjects obtained significantly better functional hearing benefits in the everyday environment with bilateral implants compared with the first implant (p=0.018).

CONCLUSION

The subjects in this study showed rapid postoperative progression within 6 months after the second implantation, and more listening benefits in noise and daily life with bilateral implants. This group of older children, who were good performers with the first implant, developed auditory perceptual competence in the second ear and achieved functional binaural benefits with their two implants. Sequential bilateral cochlear implantation should be recommended to this group of older children despite a long inter-stage interval between two implants.

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.

Bilateral cochlear implantation for children in nagasaki, Japan

Objectives

The number of patients with bilateral cochlear implant (CI) has gradually increased as patients and/or parents recognize its effectiveness. The purpose of this report is to evaluate the efficacy of 29 bilateral CI out of 169 pediatric CI users, who received auditory-verbal/oral habilitation at our hearing center.

Methods

We evaluated the audiological abilities 29 Japanese children with bilateral CIs including wearing threshold, word recognition score, speech discrimination score at 1 m from front speaker (SP), 1 m from second CI side SP, speech discrimination score under the noise (S/N ratio=80 dB sound pressure level [SPL]/70 dB SPL, 10 dB) at 1 m from front SP, word recognition score under the noise (S/N ratio=80 dB SPL/70 dB SPL, 10 dB) at 1 m from front SP.

Results

Binaural hearing using bilateral CI is better than first CI in all speech understanding tests. Especially, there were significant differences between the results of first CI and bilateral CI on SDS at 70 dB SPL (P=0.02), SDS at 1 m from second CI side SP at 60 dB SPL (P=0.02), word recognition score (WRS) at 1 m from second CI side SP at 60 dB SPL (P=0.02), speech discrimination score (SDS) at 1 m from front SP under the noise (S/N=80/70; P=0.01) and WRS at 1 m from front SP under the noise (S/N=80/70; P=0.002). At every age, a second CI is very effective. However, the results of under 9 years old were better than of over 9 years old on the mean SDS under the noise (S/N=80/70) on second CI (P=0.04). About use of a hearing aid (HA) in their opposite side of first CI, on the WRS and SDS under the noise, there were significant differences between the group of over 3 years and the group of under 10 months of HA non user before second CI.

Conclusion

These results may show important binaural effectiveness such as binaural summation and head shadow effect. Bilateral CI is very useful medical intervention for many children with severe-to-profound hearing loss in Japan as well as elsewhere.

The listening cube: a three dimensional auditory training program

OBJECTIVES

Here we present the Listening Cube, an auditory training program for children and adults receiving cochlear implants, developed during the clinical practice at the KIDS Royal Institute for the Deaf in Belgium. We provide information on the content of the program as well as guidance as to how to use it.

METHODS

The Listening Cube is a three-dimensional auditory training model that takes the following into consideration: the sequence of auditory listening skills to be trained, the variety of materials to be used, and the range of listening environments to be considered. During auditory therapy, it is important to develop training protocols and materials to provide rapid improvement over a relatively short time period. Moreover, effectiveness and the general real-life applicability of these protocols to various users should be determined.

RESULTS

Because this publication is not a research article, but comes out of good daily practice, we cannot state the main results of this study. We can only say that this auditory training model is very successful. Since the first report was published in the Dutch language in 2003, more than 200 therapists in Belgium and the Netherlands followed a training course elected to implement the Listening Cube in their daily practice with children and adults with a hearing loss, especially in those wearing cochlear implants.

CONCLUSION

The Listening Cube is a tool to aid in planning therapeutic sessions created to meet individual needs, which is often challenging. The three dimensions of the cube are levels of perception, practice material, and practice conditions. These dimensions can serve as a visual reminder of the task analysis and of other considerations that play a role in structuring therapy sessions.

Bilateral cochlear implantation

Cochlear implantation (CI) is the standard of care for the treatment of children and adults with bilateral severe-to-profound sensorineural hearing loss. Because the ultimate and continuous goal of CI teams is to improve patient performance, a potential method is bilateral CI. The potential benefits of bilateral CI include binaural summation, squelch, equivalent head shadow for each ear, improved hearing in noise, sound localization ability, and spatial release from masking. The potential disadvantages include additional or prolonged surgical procedure, unproven cost/benefit profile, and the elimination of the ability to use future technologies and/or medical therapies in the implanted ear.

Sequential bilateral cochlear implantation in children: parents' perspective and device use

OBJECTIVE

The purpose of this study was (1) to measure parental expectations before surgery of a sequentially placed second cochlear implant and compare these results with parental observations postoperatively and (2) to measure device use of the second cochlear implant and compare to unilateral implant use.

METHODS

Thirty prelingually deaf children with a unilateral cochlear implant (mean age at first implant 1.8 years) received a second implant at a mean age of 5.3 years. To measure parental expectations and observations, parents completed the Parents' Perspective before surgery of the second implant and after 12 and 24 months. The questionnaire included 1 additional question on sound localization. Device use of both the first and second implants was assessed retrospectively after 6, 12 and 24 months of implant use. Device use of the study group was also compared to a reference group of 30 unilateral implant users matched for age at second implantation.

RESULTS

Parental expectations with regard to sound localization were significantly higher than the observed changes within the first year of bilateral implant use. The observed changes in communication, listening to speech without lipreading, and speech and language skills met or surpassed parental expectations. Irrespective of age at second implantation, the second implant was significantly less worn than the first implant. No significant difference was observed between the use of the second implant of the study group and device use of the reference group. Second implant use was significantly correlated with the difference in speech recognition between the 2 implants alone.

CONCLUSIONS

Preoperative parental expectations were too high with regard to the observed localization skills within the first year of bilateral implant use. The study showed that several of these sequentially implanted children had more difficulties in wearing the second implant than in wearing the first implant during the rehabilitation period. The present results suggest that this is caused by the dominant first implant performance. Such data are of high importance in order to provide parents with realistic counseling on what they can expect from sequential bilateral cochlear implantation.