Cerebral auditory plasticity and cochlear implants

Prelingually Deaf Children With Cochlear Implants Show Better Perception of Voice Cues and Speech in Competing Speech Than Postlingually Deaf Adults With Cochlear Implants

OBJECTIVES

Postlingually deaf adults with cochlear implants (CIs) have difficulties with perceiving differences in speakers' voice characteristics and benefit little from voice differences for the perception of speech in competing speech. However, not much is known yet about the perception and use of voice characteristics in prelingually deaf implanted children with CIs. Unlike CI adults, most CI children became deaf during the acquisition of language. Extensive neuroplastic changes during childhood could make CI children better at using the available acoustic cues than CI adults, or the lack of exposure to a normal acoustic speech signal could make it more difficult for them to learn which acoustic cues they should attend to. This study aimed to examine to what degree CI children can perceive voice cues and benefit from voice differences for perceiving speech in competing speech, comparing their abilities to those of normal-hearing (NH) children and CI adults.

DESIGN

CI children's voice cue discrimination (experiment 1), voice gender categorization (experiment 2), and benefit from target-masker voice differences for perceiving speech in competing speech (experiment 3) were examined in three experiments. The main focus was on the perception of mean fundamental frequency (F0) and vocal-tract length (VTL), the primary acoustic cues related to speakers' anatomy and perceived voice characteristics, such as voice gender.

RESULTS

CI children's F0 and VTL discrimination thresholds indicated lower sensitivity to differences compared with their NH-age-equivalent peers, but their mean discrimination thresholds of 5.92 semitones (st) for F0 and 4.10 st for VTL indicated higher sensitivity than postlingually deaf CI adults with mean thresholds of 9.19 st for F0 and 7.19 st for VTL. Furthermore, CI children's perceptual weighting of F0 and VTL cues for voice gender categorization closely resembled that of their NH-age-equivalent peers, in contrast with CI adults. Finally, CI children had more difficulties in perceiving speech in competing speech than their NH-age-equivalent peers, but they performed better than CI adults. Unlike CI adults, CI children showed a benefit from target-masker voice differences in F0 and VTL, similar to NH children.

CONCLUSION

Although CI children's F0 and VTL voice discrimination scores were overall lower than those of NH children, their weighting of F0 and VTL cues for voice gender categorization and their benefit from target-masker differences in F0 and VTL resembled that of NH children. Together, these results suggest that prelingually deaf implanted CI children can effectively utilize spectrotemporally degraded F0 and VTL cues for voice and speech perception, generally outperforming postlingually deaf CI adults in comparable tasks. These findings underscore the presence of F0 and VTL cues in the CI signal to a certain degree and suggest other factors contributing to the perception challenges faced by CI adults.

Outcomes of cochlear implantation in Usher syndrome: a systematic review

PURPOSE

This study is a systematic review of the literature which seeks to evaluate auditory and quality of life (QOL) outcomes of cochlear implantation in patients with Usher syndrome.

METHODS

Systematic review of studies indexed in Medline via PubMed, Ovid EMBASE, Web of Science, CENTRAL and clinicaltrials.gov was performed up to March 9th 2022, conducted in accordance with the PRISMA statement. Patient demographics, comorbidity, details of cochlear implantation, auditory, and QOL outcomes were extracted and summarized.

RESULTS

33 studies reported over 217 cochlear implants in 187 patients with Usher syndrome, comprising subtypes 1 (56 patients), 2 (9 patients), 3 (23 patients), and not specified (99 patients). Auditory outcomes included improved sound detection, speech perception, and speech intelligibility. QOL outcomes were reported for 75 patients, with benefit reported in the majority.

CONCLUSIONS

Many patients with Usher syndrome develop improved auditory outcomes after cochlear implantation with early implantation being an important factor.

Variability in Receptive Language Development Following Bilateral Cochlear Implantation

OBJECTIVES

The primary aim was to investigate the variability in language development in children aged 5-7.5 years after bilateral cochlear implantation (CI) up to the age of 2 years, and any impact of the age at implantation and additional noncognitive or anatomical disorders at implantation.

DESIGN

Data of 84 congenitally deaf children that had received simultaneous bilateral CI at the age of ≤ 24 months were included in this retrospective study. The results of language comprehension acquisition were evaluated using a standardized German language acquisition test for normal hearing preschoolers and first graders. Data on speech perception of monosyllables and sentences in quiet and noise were added.

RESULTS

In a monosyllabic test, the children achieved a median performance of 75.0 ± 12.88%. In the sentence test in quiet, the median performance was 89 ± 12.69%, but dropped to 54 ± 18.92% in noise. A simple analysis showed a significant main effect of age at implantation on monosyllabic word comprehension (p < .001), but no significant effect of comorbidities that lacked cognitive effects (p = .24). Language acquisition values correspond to the normal range of children with normal hearing. Approximately 25% of the variability in the language acquisition tests is due to the outcome of the monosyllabic speech perception test.

CONCLUSIONS

Congenitally deaf children who were fitted bilaterally in the 1st year of life can develop age-appropriate language skills by the time they start school. The high variability in the data is partly due to the age of implantation, but additional factors such as cognitive factors (e.g., working memory) are likely to influence the variability.

Hearing and Cognition in Childhood

The human brain shows extensive development of the cerebral cortex after birth. This is extensively altered by the absence of auditory input: the development of cortical synapses in the auditory system is delayed and their degradation is increased. Recent work shows that the synapses responsible for corticocortical processing of stimuli and their embedding into multisensory interactions and cognition are particularly affected. Since the brain is heavily reciprocally interconnected, inborn deafness manifests not only in deficits in auditory processing, but also in cognitive (non-auditory) functions that are affected differently between individuals. It requires individualized approaches in therapy of deafness in childhood.

The development, validity, reliability, and norm of a preschool auditory processing assessment scale in China

BACKGROUND

Children with auditory processing deficits may face problems with language, learning, and social communication.

AIMS

To develop a Chinese auditory processing assessment scale for preschool children and establish the norms of the scale.

METHODS AND PROCEDURES

The predictive version of the scale was formed by a literature review, qualitative interviews, expert consultation, and a pre-test with a small sample. Nine kindergartens in Nanjing were selected by a stratified cluster sampling plan. First, 734 children from two kindergartens were selected for the large sample pre-test of the scale. Then, 1526 children from four kindergartens and 1151 children from three kindergartens were selected for the reliability and validity analysis and confirmatory factor analysis, respectively. The standardized norm data of the scale were established based on the 3411 points of scale data of the nine kindergartens. Finally, the clinical usefulness of the scale was analyzed by comparing the results of objective auditory processing tests in children with normal and abnormal auditory processing prompted by the score on the scale.

OUTCOMES AND RESULTS

The preschool auditory processing assessment scale includes 5 dimensions and 30 items. The Cronbach's alpha value of the scale is greater than 0.9. The confirmatory factor analysis results verify that the scale structure is reasonable. The percentile norm of the scale was established. The results of electrophysiological tests of the normal and abnormal auditory processing groups were statistically different (P < 0.05).

CONCLUSIONS AND IMPLICATIONS

The developed preschool auditory processing assessment scale has good reliability and validity. The scale is suitable for clinical application.

Deficient Recurrent Cortical Processing in Congenital Deafness

The influence of sensory experience on cortical feedforward and feedback interactions has rarely been studied in the auditory cortex. Previous work has documented a dystrophic effect of deafness in deep cortical layers, and a reduction of interareal couplings between primary and secondary auditory areas in congenital deafness which was particularly pronounced in the top-down direction (from the secondary to the primary area). In the present study, we directly quantified the functional interaction between superficial (supragranular, I to III) and deep (infragranular, V and VI) layers of feline’s primary auditory cortex A1, and also between superficial/deep layers of A1 and a secondary auditory cortex, namely the posterior auditory field (PAF). We compared adult hearing cats under acoustic stimulation and cochlear implant (CI) stimulation to adult congenitally deaf cats (CDC) under CI stimulation. Neuronal activity was recorded from auditory fields A1 and PAF simultaneously with two NeuroNexus electrode arrays. We quantified the spike field coherence (i.e., the statistical dependence of spike trains at one electrode with local field potentials on another electrode) using pairwise phase consistency (PPC). Both the magnitude as well as the preferred phase of synchronization was analyzed. The magnitude of PPC was significantly smaller in CDCs than in controls. Furthermore, controls showed no significant difference between the preferred phase of synchronization between supragranular and infragranular layers, both in acoustic and electric stimulation. In CDCs, however, there was a large difference in the preferred phase between supragranular and infragranular layers. These results demonstrate a loss of synchrony and for the first time directly document a functional decoupling of the interaction between supragranular and infragranular layers of the primary auditory cortex in congenital deafness. Since these are key for the influence of top-down to bottom-up computations, the results suggest a loss of recurrent cortical processing in congenital deafness and explain the outcomes of previous studies by deficits in intracolumnar microcircuitry.

Auditory Sensory Gating in Children With Cochlear Implants: A P50-N100-P200 Study

Background: While a cochlear implant (CI) can restore access to audibility in deaf children, implanted children may still have difficulty in concentrating. Previous studies have revealed a close relationship between sensory gating and attention. However, whether CI children have deficient auditory sensory gating remains unclear.

Methods: To address this issue, we measured the event-related potentials (ERPs), including P50, N100, and P200, evoked by paired tone bursts (S1 and S2) in CI children and normal-hearing (NH) controls. Suppressed amplitudes for S2 compared with S1 in these three ERPs reflected sensory gating during early and later phases, respectively. A Swanson, Nolan, and Pelham IV (SNAP-IV) scale was performed to assess the attentional performance.

Results: Significant amplitude differences between S1 and S2 in N100 and P200 were observed in both NH and CI children, indicating the presence of sensory gating in the two groups. However, the P50 suppression was only found in NH children and not in CI children. Furthermore, the duration of deafness was significantly positively correlated with the score of inattention in CI children.

Conclusion: Auditory sensory gating can develop but is deficient during the early phase in CI children. Long-term auditory deprivation has a negative effect on sensory gating and attentional performance.

Deafness Weakens Interareal Couplings in the Auditory Cortex

The function of the cerebral cortex essentially depends on the ability to form functional assemblies across different cortical areas serving different functions. Here we investigated how developmental hearing experience affects functional and effective interareal connectivity in the auditory cortex in an animal model with years-long and complete auditory deprivation (deafness) from birth, the congenitally deaf cat (CDC). Using intracortical multielectrode arrays, neuronal activity of adult hearing controls and CDCs was registered in the primary auditory cortex and the secondary posterior auditory field (PAF). Ongoing activity as well as responses to acoustic stimulation (in adult hearing controls) and electric stimulation applied via cochlear implants (in adult hearing controls and CDCs) were analyzed. As functional connectivity measures pairwise phase consistency and Granger causality were used. While the number of coupled sites was nearly identical between controls and CDCs, a reduced coupling strength between the primary and the higher order field was found in CDCs under auditory stimulation. Such stimulus-related decoupling was particularly pronounced in the alpha band and in top–down direction. Ongoing connectivity did not show such a decoupling. These findings suggest that developmental experience is essential for functional interareal interactions during sensory processing. The outcomes demonstrate that corticocortical couplings, particularly top-down connectivity, are compromised following congenital sensory deprivation.

Neural Recovery Function of the Auditory Nerve in Cochlear Implant Surgery: Comparison between Prelingual and Postlingual Patients

Introduction  Cochlear implants (CIs) enable objective measures of the neural function in implanted patients through the measurements of the neural response telemetry (NRT) and of the Auditory nerve Recovery Function (REC). These measurements help in programming the speech processor and understanding the auditory system. Objective  To compare the NRT and the REC in prelingual and postlingual implanted patients. Methods  An observational, descriptive and prospective study was carried out. The NRT and the REC (through the T0, A, and tau parameters) were evaluated in individuals submitted to CI surgery, who were divided into two groups: prelingual and postlingual patients. Results  In total, 46 patients were evaluated. Data analysis showed no statistically significant difference between the NRT measurements and the T0, A, and Tau of the REC in the comparison between the two groups, except for the NRT in the basal cochlear region. Conclusion  There was no statistically significant difference in the REC in pre- and postlingual patients.

Development of auditory perception in preschool children

OBJECTIVE

The aim of this study was to determine whether the auditory skills presented by five-year-old children can predict their performance in auditory processing (AP) tests at seven years old.

DESIGN

Thirty-five children were evaluated for AP at two different times. At evaluation 1, the children were between 5 years 2 months and 6 years 1 month of age, and at evaluation 2, they were between 7 years 1 month and 7 years 8 months of age. The interval between the evaluations ranged from 18 to 23 months. After evaluation 2, the 7-year-olds were classified according to their performance on central AP tests. The children were divided into three groups: GI included nine children with at least two AP tests that scored two standard deviations below the mean and the presence of a speech complaint; GII included 18 children with at least two AP tests that scored two standard deviations below the mean and no speech complaints; and GIII included eight children with no more than one test scored two standard deviations below the mean and no speech disorders complaint. The analysis was performed considering each test individually and as a battery of applied tests. From the results obtained, a discriminant analysis was performed to assess the differences in test performance between the groups when the children were 5 years old.

RESULTS

The discriminant analysis showed that with the results obtained during evaluation 1, it was possible to predict which group 74.3% of the children would be classified into after evaluation 2. The percentage of correct classifications for each group was 77.8% for GI, 66.7% for GII and 87.5% for GIII. That is, 87.5% of the children who were classified as GIII after evaluation 2 had already demonstrated good auditory performance in the tests applied at 5 years of age.

CONCLUSIONS

Children who exhibited lower scores on AP tests at 7 years of age had demonstrated poor auditory perception at 5 years of age. This finding is relevant because it offers the possibility of stimulating or training these auditory skills in preschoolers to foster their development.

Neuronal Development of Hearing and Language: Cochlear Implants and Critical Periods

The modern cochlear implant (CI) is the most successful neural prosthesis developed to date. CIs provide hearing to the profoundly hearing impaired and allow the acquisition of spoken language in children born deaf. Results from studies enabled by the CI have provided new insights into ( a) minimal representations at the periphery for speech reception, ( b) brain mechanisms for decoding speech presented in quiet and in acoustically adverse conditions, ( c) the developmental neuroscience of language and hearing, and ( d) the mechanisms and time courses of intramodal and cross-modal plasticity. Additionally, the results have underscored the interconnectedness of brain functions and the importance of top-down processes in perception and learning. The findings are described in this review with emphasis on the developing brain and the acquisition of hearing and spoken language.

Results of Postoperative, CT-based, Electrode Deactivation on Hearing in Prelingually Deafened Adult Cochlear Implant Recipients

OBJECTIVE

To test the use of a novel, image-guided cochlear implant (CI) programming (IGCIP) technique on prelingually deafened, adult CI recipients.

STUDY DESIGN

Prospective unblinded study.

SETTING

Tertiary referral center.

PATIENTS

Twenty-six prelingually deafened adult CI recipients with 29 CIs (3 bilateral).

INTERVENTION(S)

Temporal-bone CT scans were used as input to a series of semiautomated computer algorithms which estimate the location of electrodes in reference to the modiolus. This information was used to selectively deactivate suboptimally located electrodes, i.e., those for which the distance from the electrode to the modiolus was further than a neighboring electrode to the same site. Patients used the new IGCIP program exclusively for 3-5 weeks.

MAIN OUTCOME MEASURE(S)

Minimum Speech Test Battery (MSTB), quality of life (QOL), and spectral modulation detection (SMD).

RESULTS

On average one-third of electrodes were deactivated. At the group level, no significant differences were noted for MSTB measures nor for QOL estimates. Average SMD significantly improved after IGCIP reprogramming, which is consistent with improved spatial selectivity. Using 95% confidence interval data for CNC, AzBio, and BKB-SIN at the individual level, 76 to 90% of subjects demonstrated equivocal or significant improvement. Ultimately 21 of 29 (72.41%) elected to keep the IGCIP map because of perceived benefit often substantiated by improvement on either MSTB, QOL, and/or SMD.

CONCLUSIONS

Knowledge of the geometric relationship between CI electrodes and the modiolus appears to be useful in adjusting CI maps in prelingually deafened adults. Long-term improvements may be observed resulting from improved spatial selectivity and spectral resolution.

AHL, SSD and bimodal CI results in children

OBJECTIVE

This article aims to demonstrate that children with asymmetric hearing loss (AHL), specifically those with single side deafness (SSD condition) and pure SSD, with substantial hearing (>70% normal speech discrimination) in the ear with hearing aid (HA), obtain clinically relevant speech perception benefit after cochlear implantation in the contralateral side.

RESULTS

Retrospective study of two groups: (1) 36 AHL children with bimodal hearing and (2) SSD children with SSD. They had follow-ups of 24 and 12 months duration, respectively. The AHL children where implanted on one ear and depending on the contralateral ear condition, they were divided into two groups: children who reach a disyllabic speech test score lower than 50% in quiet at 65dB-SPL without lip reading (27) and children with test score higher than 70% (9). The second group consisted on 2 children implanted to obtain SSD condition, as preliminary data, with 1 year of follow-up. They showed benefits of binaural stimulation.

CONCLUSION

Children in a bimodal situation, with substantial hearing (>70% speech discrimination) in the ear with HA, obtain clinically relevant speech perception benefit after cochlear implantation in the contralateral side.

Pediatric Cochlear Implantation-Why the Delay

The aim of the study was to evaluate the factors that act as barriers and delay the process of cochlear implantation in children with congenital profound sensorineural hearing loss. This is a cross sectional observational study in which 154 children with profound sensorineural deafness attending ENT outdoor from Jan 2013 to June 2014 at Sri Aurobindo Institute of Medical College and PG Institute, Indore, were included in the study. Information was taken from the parents of the candidates regarding the reasons for the delay in reporting, the delay in intervention and a detailed history was also taken to evaluate the possible reason for the hearing loss with the help of open ended questions. The most common cause for the delay in reporting was lack of information about the availability of technique and procedure for cochlear implant. Financial constrain was the most common cause for the delay in getting the cochlear implant surgery.

Delayed prelingual cochlear implantation in childhood and puberty

OBJECTIVE

To evaluate the results of delayed cochlear impantion performed in childhood and puberty in the light of speech language pathology assessments.

METHODS

Totally 49 children with prelingual profound hearing loss were included in the study. All children received a cochlear implant between the ages of 5 and 19 years (Group 1 aged between 5 and 9 years, group 2 aged between 10 and 14 years, group 3 aged between and 15 and 19 years). The MAIS, MUSS and PLS-4 scores of children were evaluated one month before, and one year and two years after the operation. The descriptive statistics included several independent variables; age of implantation; gender; trade name of the implant; preoperative duration of hearing aid use; preoperative special education, family support and additional handicap. These variables were categorical variables. We used repeated measures analysis of variance to test improvements in MAIS, MUSS and PLS scores, and whether this improvement depend on the independent variables. In addition, we also tested the interaction between time and the independent variables.

RESULTS

The preoperative MAIS, MUSS and language scores were significantly higher in older children compared to younger children (p<0.01). After two years these scores were similar between the all age groups (p>0.4). There was a significant age and time interaction (p=0.005). That is, improvement continued in all age groups in a parallel way and group 2 reached to the level of group 1 after two years. However, group 3 almost reached to a plateau level after two years. The family support was associated with the MAIS, MUSS and language scores of the patients (p=0.01), and there was a family support-time interaction (p<0.0001). In group 1 and 2, the way of communication shifted from total communication (lip reading, sign language, auditory) to auditory-verbal communication in a significant number of the patients (p<0.01). However, that change in the way of communication was not statistically significant in group 3 (p>0.05).

CONCLUSION

The decision of delayed cochlear implantation in children can be made in the light of following parameters. A good family support is most important. The patients must be wearing hearing aids regularly since early childhood, and preferably use the auditory verbal communication. Evaluation of the patient with MAIS, MUSS and PLS is important to understand the level of receptive and expressive communication level.

Audiovisual spoken word training can promote or impede auditory-only perceptual learning: prelingually deafened adults with late-acquired cochlear implants versus normal hearing adults

Training with audiovisual (AV) speech has been shown to promote auditory perceptual learning of vocoded acoustic speech by adults with normal hearing. In Experiment 1, we investigated whether AV speech promotes auditory-only (AO) perceptual learning in prelingually deafened adults with late-acquired cochlear implants. Participants were assigned to learn associations between spoken disyllabic C(=consonant)V(=vowel)CVC non-sense words and non-sense pictures (fribbles), under AV and then AO (AV-AO; or counter-balanced AO then AV, AO-AV, during Periods 1 then 2) training conditions. After training on each list of paired-associates (PA), testing was carried out AO. Across all training, AO PA test scores improved (7.2 percentage points) as did identification of consonants in new untrained CVCVC stimuli (3.5 percentage points). However, there was evidence that AV training impeded immediate AO perceptual learning: During Period-1, training scores across AV and AO conditions were not different, but AO test scores were dramatically lower in the AV-trained participants. During Period-2 AO training, the AV-AO participants obtained significantly higher AO test scores, demonstrating their ability to learn the auditory speech. Across both orders of training, whenever training was AV, AO test scores were significantly lower than training scores. Experiment 2 repeated the procedures with vocoded speech and 43 normal-hearing adults. Following AV training, their AO test scores were as high as or higher than following AO training. Also, their CVCVC identification scores patterned differently than those of the cochlear implant users. In Experiment 1, initial consonants were most accurate, and in Experiment 2, medial consonants were most accurate. We suggest that our results are consistent with a multisensory reverse hierarchy theory, which predicts that, whenever possible, perceivers carry out perceptual tasks immediately based on the experience and biases they bring to the task. We point out that while AV training could be an impediment to immediate unisensory perceptual learning in cochlear implant patients, it was also associated with higher scores during training.

The effect of age at cochlear implantation outcomes in Saudi children

OBJECTIVES

To determine for the effect of age (late versus early age) on the cochlear implant outcomes; in terms of language development, auditory skills, speech perception, and production outcomes).

METHODS

67 children were included in the study out of 93 implanted cases in the study period. Children were classified into 2 groups according to age at time of implantation. Group 1 contained 43 children who were implanted before the age of 5 years. Group 2 contained 24 children who were implanted after the age of 5 years. All children were evaluated pre-operatively and at 3, 6, 12, 24 months device experience using the language screening test, Standardized Arabic Language test, Listening Progress Profile (LiP Test), the Monosyllabic-Trochee-polysyllabic Test (MTP), and the meaningful Auditory Integration Scale (MAIS) Test. Charts with incomplete data were excluded.

RESULTS

Only 67 children had complete data out of 93 patients. The mean age (in months) for Group 1 was (43.37±8.63) and for Group 2 was (70.38±9.97) at time of implantation. Significantly higher mean values were detected for Group 2 in comparison to Group 1 in the pre-operative period. No significant difference was detected after 2 years evaluation using the test battery for language development and auditory skills.

CONCLUSIONS

Children who were implanted under the 5 years of age had a better outcome in the form of better auditory skills, speech perception, and language production. Limited resources and the absence of a national hearing screening program in Saudi Arabia result in the late presentation of children for evaluation and intervention of hearing problem; this late intervention reduces the benefits the late - implanted children derive from cochlear implantation.

Cortical plasticity after cochlear implantation

The most dramatic progress in the restoration of hearing takes place in the first months after cochlear implantation. To map the brain activity underlying this process, we used positron emission tomography at three time points: within 14 days, three months, and six months after switch-on. Fifteen recently implanted adult implant recipients listened to running speech or speech-like noise in four sequential PET sessions at each milestone. CI listeners with postlingual hearing loss showed differential activation of left superior temporal gyrus during speech and speech-like stimuli, unlike CI listeners with prelingual hearing loss. Furthermore, Broca's area was activated as an effect of time, but only in CI listeners with postlingual hearing loss. The study demonstrates that adaptation to the cochlear implant is highly related to the history of hearing loss. Speech processing in patients whose hearing loss occurred after the acquisition of language involves brain areas associated with speech comprehension, which is not the case for patients whose hearing loss occurred before the acquisition of language. Finally, the findings confirm the key role of Broca's area in restoration of speech perception, but only in individuals in whom Broca's area has been active prior to the loss of hearing.

Listening effort with cochlear implant simulations

PURPOSE

Fitting a cochlear implant (CI) for optimal speech perception does not necessarily optimize listening effort. This study aimed to show that listening effort may change between CI processing conditions for which speech intelligibility remains constant.

METHOD

Nineteen normal-hearing participants listened to CI simulations with varying numbers of spectral channels. A dual-task paradigm combining an intelligibility task with either a linguistic or nonlinguistic visual response-time (RT) task measured intelligibility and listening effort. The simultaneously performed tasks compete for limited cognitive resources; changes in effort associated with the intelligibility task are reflected in changes in RT on the visual task. A separate self-report scale provided a subjective measure of listening effort.

RESULTS

All measures showed significant improvements with increasing spectral resolution up to 6 channels. However, only the RT measure of listening effort continued improving up to 8 channels. The effects were stronger for RTs recorded during listening than for RTs recorded between listening.

CONCLUSION

The results suggest that listening effort decreases with increased spectral resolution. Moreover, these improvements are best reflected in objective measures of listening effort, such as RTs on a secondary task, rather than intelligibility scores or subjective effort measures.

Cochlear implant outcomes in adults and adolescents with early-onset hearing loss

OBJECTIVES

The aims of the study were to investigate (1) speech perception outcomes in people with an early-onset hearing loss (HL) who received a cochlear implant as an adolescent or adult, (2) prognostic factors associated with positive speech perception outcomes, and (3) self-report outcomes in these participants.

DESIGN

Outcomes for 38 implant recipients with a Nucleus device were investigated retrospectively. All participants were diagnosed with a bilateral HL at age #3 yr and were implanted at age 14 yr or older. Nineteen participants had confirmed bilateral, severe to profound HL at age #12 mo (prelingual); nine had confirmed bilateral, severe to profound HL at age.12 mo and #3 yr (perilingual); and the remaining 10 had a diagnosis of bilateral sensorineural HL at age #3 yr which progressed to severe to profound HL after 3 yrs of age (progressive). There were 24 females and 14 males, and the average age at implantation was 33 yr (range 5 14-65 yr). Closed-set and open-set speech perception tests administered pre- and postimplant were analyzed for all participants, in addition to self-report survey measures of benefit, satisfaction, and implant usage.

RESULTS

Participants were placed into one of five hierarchic categories of speech perception performance preimplantation and at 12 mo postimplantation. The categories ranged from sound detection only (category 1) to excellent open-set speech perception (category 5). To be in category 4 or 5, the participant had to score.30% words correct on a recorded version of either the Central Institute for the Deaf Everyday Sentence Lists or the City University of New York Sentences. Before implantation, two recipients (5%) were in category 4 or 5 compared with 20 (53%) at 12 mo postimplant. Consistent with previous studies, there was large intersubject variability in speech scores. Three factors accounted for 63% of the variance on open-set sentence test scores, postimplant: mode of communication in childhood (oral versus total communication/sign), stable as opposed to progressive loss, and time without a hearing aid on the implant ear. More than 80% of survey respondents used their device.8 hr a day, and 90% reported that their ability to understand speech with visual cues was "much better" with the implant. In addition, all reported being satisfied with the device.

CONCLUSION

These results indicate that a cochlear implant should be considered as an option for adults and adolescents with early-onset HL. The majority of participants gained benefit from the device and were satisfied with it. In addition, a substantial number gained good open-set speech perception ability, postimplant. Recipients who used oral communication in childhood, had a progressive loss, and wore a hearing aid on the implant ear up to the time of surgery were more likely to obtain better speech perception outcomes.

Soft tissue complications after pediatric cochlear implantation in children younger than 12 months

OBJECTIVES

Children are undergoing cochlear implantation younger than ever before. There has been some concern that young children may have an increased risk of soft tissue complications than older age groups. We aim to review the major and minor soft tissue complications after pediatric cochlear implantation in the age group of younger than 12 months.

STUDY DESIGN

Retrospective case review.

METHODS

Patients were identified from the cochlear implant program database of more than 1,000 children at the Hospital for Sick Children, Toronto, Canada. Demographic data, cause of hearing loss, and time of the onset of hearing loss were recorded.

RESULTS

A total of 66 patients were identified (94 implants) in the age group of younger than 12 months. Of these, there was 1 minor complication (implanted at 8 mo)-skin infection around implant 14 days later treated with antibiotics. There were no major complications.

CONCLUSION

Cochlear implantation in children younger than 12 months does not increase the risk of soft tissue complications.

Hearing history influences voice gender perceptual performance in cochlear implant users

OBJECTIVES

The study was carried out to assess the role that five hearing history variables (chronological age, age at onset of deafness, age of first cochlear implant [CI] activation, duration of CI use, and duration of known deafness) play in the ability of CI users to identify speaker gender.

DESIGN

Forty-one juvenile CI users participated in two voice gender identification tasks. In a fixed, single-interval task, subjects listened to a single speech item from one of 20 adult male or 20 adult female speakers and had to identify speaker gender. In an adaptive speech-based voice gender discrimination task with the fundamental frequency difference between the voices as the adaptive parameter, subjects listened to a pair of speech items presented in sequential order, one of which was always spoken by an adult female and the other by an adult male. Subjects had to identify the speech item spoken by the female voice. Correlation and regression analyses between perceptual scores in the two tasks and the hearing history variables were performed.

RESULTS

Subjects fell into three performance groups: (1) those who could distinguish voice gender in both tasks, (2) those who could distinguish voice gender in the adaptive but not the fixed task, and (3) those who could not distinguish voice gender in either task. Gender identification performance for single voices in the fixed task was significantly and negatively related to the duration of deafness before cochlear implantation (shorter deafness yielded better performance), whereas performance in the adaptive task was weakly but significantly related to age at first activation of the CI device, with earlier activations yielding better scores.

CONCLUSIONS

The existence of a group of subjects able to perform adaptive discrimination but unable to identify the gender of singly presented voices demonstrates the potential dissociability of the skills required for these two tasks, suggesting that duration of deafness and age of cochlear implantation could have dissociable effects on the development of different skills required by CI users to identify speaker gender.

Cochlear implantation in late-implanted adults with prelingual deafness

PURPOSE

The purpose of this study was to examine the effect of cochlear implantation (CI) on prelingually deafened participants who were implanted as adults. The effect of the CI was examined with regard to the following variables: communication, family, social skills, education, and work satisfaction with one's life, loneliness, and self-esteem.

MATERIALS AND METHODS

Thirty-eight adults participated. Four self-report questionnaires were used at 2 points in time: before and after CI.

RESULTS

The research findings show significant differences in the reports of most variables before and after implantation. The participants felt better with regard to communication, social skills, education, and work and satisfaction with one's life after implantation in comparison to their feelings before implantation. Furthermore, they felt less lonely after implantation. However, there were no significant differences before and after implantation regarding their feelings within the family and regarding their self-esteem.

CONCLUSIONS

The results demonstrated the need to evaluate the benefits resulting from the CI not only with traditional clinical measures but with additional measures as well. Furthermore, they demonstrated the benefit of the CI on the positive psychosociological implications of prelingually deafened adults.

Subcortical plasticity following perceptual learning in a pitch discrimination task

Practice can lead to dramatic improvements in the discrimination of auditory stimuli. In this study, we investigated changes of the frequency-following response (FFR), a subcortical component of the auditory evoked potentials, after a period of pitch discrimination training. Twenty-seven adult listeners were trained for 10 h on a pitch discrimination task using one of three different complex tone stimuli. One had a static pitch contour, one had a rising pitch contour, and one had a falling pitch contour. Behavioral measures of pitch discrimination and FFRs for all the stimuli were measured before and after the training phase for these participants, as well as for an untrained control group (n = 12). Trained participants showed significant improvements in pitch discrimination compared to the control group for all three trained stimuli. These improvements were partly specific for stimuli with the same pitch modulation (dynamic vs. static) and with the same pitch trajectory (rising vs. falling) as the trained stimulus. Also, the robustness of FFR neural phase locking to the sound envelope increased significantly more in trained participants compared to the control group for the static and rising contour, but not for the falling contour. Changes in FFR strength were partly specific for stimuli with the same pitch modulation (dynamic vs. static) of the trained stimulus. Changes in FFR strength, however, were not specific for stimuli with the same pitch trajectory (rising vs. falling) as the trained stimulus. These findings indicate that even relatively low-level processes in the mature auditory system are subject to experience-related change.

Cochlear implantation in adolescents with prelinguistic deafness

Objective: The aims of this study were to examine auditory function in a group of adolescents with prelingual deafness who received cochlear implants (CI) and to identify poor-outcome predictors in order to define reliable prognostic indicators useful in selecting patients for CI.

Study Design: Prospective study.

Setting: The study was conducted in the Audiology Unit of Cà Granda Ospedale Maggiore Policlinico, Milan, Italy.

Subjects and Methods: The study involved 45 adolescents (mean age at implantation: 13.4 ± 2.6 years, range: 11-18) with profound congenital hearing impairment with a follow-up of three years. Preimplantation and postimplantation auditory performance and speech perception were evaluated using the mean score of three hearing and speech perception tests (vowel-consonant-vowel [VCV], identification of disyllabic words, and recognition of short sentences) performed in auditory-only listening conditions.

Results: Significant improvements in all speech perception tests were observed after CI. However, 15 cases were considered “poor performers” (i.e., the auditory performance of these patients was less than 30 percent). The diagnosis of deafness in these subjects was significantly delayed (18.07 ± 6.25 and 34.4 ± 10.26 months in good and poor performers, respectively, P = 0.006), and their hearing threshold was significantly lower than in the good users group. The mean age at CI was 12.8 ± 2.33 and 14.53 ± 2.70 years in good and poor performers, respectively ( P = ns).

Conclusion: CI was shown to be a useful device with the ability to reverse the adverse consequences of hearing loss, particularly for prelingual adolescents who receive implantation early in life and who present a hearing threshold of 100 dB or better both at diagnosis and at surgery.

Age sensitivity in the acquisition of lexical tone production: evidence from children with profound congenital hearing impairment after cochlear implantation

OBJECTIVES

This study investigated the effects of implant experience and age at implantation on the Cantonese tone production of children with cochlear implants. The study also examined whether there was a particular age at which children were more responsive to acquiring tones.

METHODS

The study included 45 children who had received unilateral cochlear implants at a mean age of 65.56 months. The subjects were grouped according to their age at cochlear implantation and were assessed annually for 5 years thereafter. A picture-naming task was used to measure their tone production performance.

RESULTS

A simple effect of age at implantation was significant at all testing intervals except at the preoperative data point. Children who were younger than 4 years of age when they received their implants scored significantly higher than did the 2 older groups at various testing intervals. A significant simple effect of implant experience was also found. Progress was most striking in children who received their implants before the age of 4 years.

CONCLUSIONS

For the most effective acquisition of Cantonese lexical tones, children should undergo early cochlear implantation. For children who receive implants before the age of 4 years, benefits are noted in tone production ability in terms of a faster rate of improvement within a shorter period of time.

Perception of speech by prelingual pre-adolescent and adolescent cochlear implant users

This study was undertaken to assess the speech perception benefits, 24 months after cochlear implantation (CI), in 20 young people (age at CI, 8-18.5 years) with prelingual profound hearing loss, in addition to the use of a proposed CI candidacy assessment profile. Speech perception was evaluated in terms of word and sentence perception before CI, and at six-monthly intervals for two years after CI. Before undergoing CI, all participants were tested on a pre-implantation assessment profile. Compared to the pre-CI findings, group results over 24 months post-CI demonstrated improved speech perception abilities reaching, on average, 46% for word recognition, 71.3% for sentences in quiet, and 33.6% for sentences in noise. Pre-CI profile scores correlated significantly with all speech perception results obtained 24 months after CI. Thus, despite their relatively late ages at implantation, all participants showed gradually improving performance in speech perception. The results showed a high variability in the outcomes of the participants. The pre-CI profile appeared to be useful in formulating realistic expectations of CI outcome during pre-implantation consultations, suggesting that expectations can and should be managed according to each patient's pre-implantation assessment.

Behavioral and electrophysiological measures of auditory change detection in children following late cochlear implantation: a preliminary study

OBJECTIVE

The purpose of the current study was to longitudinally assess the development of automatic sound feature discrimination and compare it to behavioral discrimination in late-implanted cochlear implant users.

METHODS

Scalp-recorded auditory evoked potentials (AEPs) and behavioral discrimination of frequency, duration and intensity differences within an oddball paradigm using complex stimuli were recorded in three late-implanted cochlear implant subjects beginning on turn-on day.

RESULTS

Variable results were obtained in behavioral and AEPs that were consistent with the amount of pre-implant auditory experience each subject had. The best user showed rapid development of neurophysiologic indices of change detection along with improvement in behavioral and real-world auditory skills. In contrast, there were no recordable AEPs in the poorer CI user and there was little change in behavioral outcomes.

CONCLUSION

There is evidence of utilization of usual auditory processing pathways in the AEPs of some children who receive cochlear implants late in their childhood. Some plasticity in the auditory cortical pathways may be present despite prolonged auditory deprivation in school-aged children who are late-implanted cochlear implant recipients.

Long-term follow-up of infants (4-11 months) fitted with cochlear implants

CONCLUSION

In this study the outcomes from several indices (Category of Auditory Performance, CAP; Peabody Picture Vocabulary Test (Revised), PPVT-R; Test of Reception of Grammar, TROG; and Speech Intellegibility Rating, SIR) in three groups of children with different ages at implantation (from 4 to 36 months) with a follow-up time from 4 to 9 years demonstrate that very early cochlear implantation (<11 months) provides normalization of audio-phonologic parameters with no complications.

OBJECTIVES

The aim of the present study was to investigate the efficacy of cochlear implants (CIs) in infants who were implanted at < 11 months of age versus children operated at later age (i.e. 12-36 months) and to document whether children who receive a CI below 11 months of age are able to achieve age-appropriate expected spoken language skills, at a follow-up time from 4 to 9 years.

SUBJECTS AND METHODS

From November 1998 to November 2007, 185 children received CIs and 34 received auditory brainstem implants in our department. The present study focuses on 13 children implanted at ages younger than 12 months (4-11 months; mean, 8.2; SD = 2.4) and fitted with CIs between November 1998 and March 2004. To avoid bias these children were selected from a larger longitudinal cohort of pediatric CI recipients fitted with CIs because they all were implanted with the same cochlear device (Nucleus CI 24 M) during the same period. Postoperatively auditory abilities were evaluated at the latest follow-up, from 4 to 9 years after surgery, with CAP, PPVT-R, TROG, and SIR. The results obtained in this group of 13 children were compared with those obtained in two groups of children implanted at later ages (12-23 and 24-36 months, respectively).

RESULTS

No complication has been observed so far. The highest score of CAP function was achieved in all the three groups but at different intervals from CI activation as function of age at CI implantation. The rate of receptive language growth (PPVT-R) provides distinctive evidence that only the scores of the first group overlap the line of normal-hearing children, whereas the second and third group never reached the values of normal peers even after 9 years of CI use. TROG outcomes clearly indicate that only children from the first group (77%) are in the 76-100 percentile at 5 years follow-up. At 9 years follow-up, 100% of children in the first group, 38% in the second group, and 20% in the third group are in the 76-100 percentile. The SIR outcomes at the 5 years follow-up indicate that none of children was identified within the first two categories, only children from the third group (18%) were identified in category 3, all infants of the first group, 80% of group 2, and 63% of the third group were identified in category 5. At the 9 years follow-up, the number of children from the third group identified in category 3 was reduced to 10%, the second and third groups displayed a slightly higher percentage of children in category 5, but the difference from the values observed at the 5-year follow-up is not significant.

Cochlear implant candidacy in the United States: prevalence in children 12 months to 6 years of age

OBJECTIVE

Pediatric cochlear implantation has been demonstrated to be effective for children as well as cost effective for society. One of Healthy People 2010 goals is to increase the number of people who are deaf or significantly hard of hearing to begin to use a cochlear implant system. NIDCDs Healthy Hearing Progress Reports from 1999 reported that only 2 out of every 1000 adults who are deaf or hard of hearing received a cochlear implant. There were two main objectives for this study: (1) to estimate the number of children between the ages of 12 months and 6 years of age with severe to profound bilateral hearing loss who could benefit from a cochlear implant and (2) to determine if the number of children projected to be candidates received this medical care.

METHODS

Using the 2000 US Census Data from children 12 months to 6 years, the number of children with severe to profound bilateral hearing loss was calculated. Children who would be considered "neurologically devastated" and the children with absent eighth nerves were excluded from the calculations.

RESULTS

Based on the total population of slightly over 231 million, 15,219 children presented with severe to profound hearing loss. Taking into account some exclusions, 12,816 children would be considered cochlear implant candidates. Based on the number of children who were implanted in 2000, approximately 55% of the projected number of candidates received a cochlear implant.

CONCLUSION

Even though the estimates do not reflect a direct measure of actual candidates in the targeted age groups, the population who could benefit from this technology is still being significantly underserved in the United States. With a continued shortage of qualified personnel to serve these children, insufficient reimbursement rates, and disparities in implantation rates based on ethnicity and socioeconomic status, the question remains can we truly meet the needs of these children?

Effects of age at onset of deafness and electrical stimulation on the developing cochlear nucleus in cats

This study examined the effects of deafness and intracochlear electrical stimulation on the anatomy of the cochlear nucleus (CN) after a brief period of normal auditory development early in life. Kittens were deafened by systemic ototoxic drug injections either as neonates or starting at postnatal day 30. Total CN volume, individual CN subdivision volumes, and cross-sectional areas of spherical cell somata in the anteroventral CN (AVCN) were compared in neonatally deafened and 30-day deafened groups at 8 weeks of age and in young adults after approximately 6 months of electrical stimulation initiated at 8 weeks of age. Both neonatal and early acquired hearing loss resulted in a reduction in CN volume as compared to normal hearing cats. Comparison of 8- and 32-week old groups indicated that the CN continued to grow in both deafened groups despite the absence of auditory input. Preserving normal auditory input for 30 days resulted in a significant increase in both total CN volume and cross-sectional areas of spherical cell somata, as compared to neonatally deafened animals. Restoring auditory input in these developing animals by unilateral intracochlear electrical stimulation did not elicit any difference in CN volume between the two sides, but resulted in 7% larger spherical cell size on the stimulated side. Overall, the brief period of normal auditory development and subsequent electrical stimulation maintained CN volume at 80% of normal and spherical cell size at 86% of normal ipsilateral to the implant as compared to 67% and 74%, respectively, in the neonatally deafened group.

Will they catch up? The role of age at cochlear implantation in the spoken language development of children with severe to profound hearing loss

PURPOSE

The authors examined the benefits of younger cochlear implantation, longer cochlear implant use, and greater pre-implant aided hearing to spoken language at 3.5 and 4.5 years of age.

METHOD

Language samples were obtained at ages 3.5 and 4.5 years from 76 children who received an implant by their 3rd birthday. Hierarchical linear modeling was used to identify characteristics associated with spoken language outcomes at the 2 test ages. The Preschool Language Scale (I. L. Zimmerman, V. G. Steiner, & R. E. Pond, 1992) was used to compare the participants' skills with those of hearing age-mates at age 4.5 years.

RESULTS

Expected language scores increased with younger age at implant and lower pre-implant thresholds, even when compared at the same duration of implant use. Expected Preschool Language Scale scores of the children who received the implant at the youngest ages reached those of hearing age-mates by 4.5 years, but those children implanted after 24 months of age did not catch up with hearing peers.

CONCLUSION

Children who received a cochlear implant before a substantial delay in spoken language developed (i.e., between 12 and 16 months) were more likely to achieve age-appropriate spoken language. These results favor cochlear implantation before 24 months of age, especially for children with aided pure-tone average thresholds greater than 65 dB prior to surgery.

A Comparison of Postcochlear Implantation Speech Scores in an Adult Population

OBJECTIVES

The vast majority of cochlear implant recipients realize significant improvement in speech perception. However, there continue to be a small group that does not realize such a benefit. In an effort to identify possible predictors for this, we have compared pre- and postimplant audiologic data using Hearing In Noise Test (HINT), City University of New York (CUNY), or Central Institute for the Deaf (CID) scores for 445 consecutive English-speaking adult patients followed for a minimum of 1 year postimplantation in two distinct groups, poor versus excellent performers.

STUDY DESIGN

Retrospective.

METHODS

Poor performers were those who realized a worsening, no improvement, or an improvement of less than 10%. This group numbered 58 (13%). High performers consisted of a cadre of 194 (44%) patients who scored between 91 and 100% postimplantation. Demographic data relating to onset of deafness, education exposure, etiology, etc., were evaluated.

RESULTS

Of the poor performers, 33 (57%) were pre-/perilingually deafened. Of these, 79% had not received any auditory/oral training in childhood. On the other hand, a total of 109 implant recipients were individuals who were pre-/perilingually deafened. Of these, 24 were in the excellent performer category. All were identified early and were recipients of a strong auditory/oral education. Of the high performers, 170 (88%) were deafened late. Other findings such as preoperative electronystagmography with caloric testing, hearing aid use, device type, and high-resolution computed tomography scan of the temporal bone will be discussed for both groups.

CONCLUSIONS

A high preimplant speech score, auditory verbal therapy, and postlingual deafness statistically correlate with higher postimplant speech scores 1 year after cochlear implantation. Device type, caloric response and hearing aid use preimplantation, age at surgery, and sex do not statistically correlate with either poor or excellent speech discrimination scores postcochlear implantation.

Morphometric comparison of the human corpus callosum in deaf and hearing subjects: an MRI study

Auditory cortices are interconnected to each other by fibers passing through the corpus callosum (CC). In totally deaf persons no auditory impulses are conveyed to the auditory cortices, hence the auditory pathways become nonfunctional. It was reported that there has been cross-modal plasticity between auditory, visual, and somatosensory cortices. In this study, our aim was to make a comparison in the CC morphometry in hearing subjects and in a selected group in which the auditory system was deprived before the age of 2. 18 deaf and 18 hearing male, handedness matched volunteers, ages varying between 28 and 56 years old were examined. Audiometrical tests were applied to both groups and then T1-weighted midsagittal MR images were obtained. Certain dimensions and areas were measured on these images. There were no statistically significant difference between deaf and hearing subjects, either when dimensions and areas were analyzed by multivariate analysis of variance or when areas were analyzed by univariate analysis of variance. Absence of any significant morphometric difference in the CC of deaf subjects could be thought as an evidence of reflection of functional cortical plasticity.

Evaluación del implante coclear como técnica de tratamiento de la hipoacusia profunda en pacientes pre y post locutivos

INTRODUCTION

These are the objectives planned for this study: 1. Evaluate the results from the communication point of view. 2. Evaluate the cochlear implant (CI) impact on the quality of life. 3. Evaluate medical complications and technical failures. 4. Assess direct and indirect costs generated during the phases of a cochlear implantation programme. 5. Determine which factors have a high impact on the clinical evolution and the financial cost.

MATERIALS AND METHOD

A population of 877 patients, postlingual and prelingual, adults and children, have been studied. They were treated in 5 Spanish centres with cochlear implant programmes. Audiometric tests and global questionnaires on life quality have been carried out. Medical and CI technology complications have also been computed. Direct and indirect economic costs of a cochlear implant have been calculated.

RESULTS

Postlocutive-implanted patients reached the 40 dB SPL threshold in the Pure Tone Audiometry, and this result was maintained during the 12-year evolution. In Vowels test, it evolved from a 30% on pre-stimulation to 80-90%, in Disyllables words test it evolved from a 10% to a 50-60%, and in CID Sentences test it evolved from an 18% to a 60-70%. In the prelocutive population, results were influenced by the child's age at implantation. The best results were obtained by the children who had been implanted earlier. Those implanted between 0 and 3 years old evolved in the Vowels test from 0% during pre-stimulation to 95%, from a 0% to a 90% in Disyllables words test and from a 0% to a 90-95% in CID Sentences test. Also, the speech acquisition and development of the pre-locutive population was also influenced by the implantation age. An 80% of postlocutive adult patients stated a mood and sociability improvement after the cochlear implantation. They did not show health changes in general nor relevant modifications in the attention they usually received from relatives and friends. Severe medical-surgical complications were registered for a 3.42% of the cases, a 7.06% of mild medical-surgical complications and a 3.07% of technical breakdowns in the internal components of the CI. Financial cost of implantation for a post-locutive adult oscillated between 36,912 Euro and 37,048 Euro, and between 37,689 Euro and 44,273 Euro for a pre-locutive child.

CONCLUSIONS

Cochlear implants clearly enhance communication skills of the implantees. Results obtained for the prelocutive implanted population justify the creation of hearing screening programmes in new-borns. Postlocutive implanted adults have expressed satisfaction for the results obtained. However, they did perceive some limitations in situations of unfavourable acoustic conditions. An analysis of direct and indirect costs related to a CI programme has been made. It may be useful to carry out reports on the cost-benefit ratio in this field. The low index of complications observed shows which cochlear implant treatment technique complies with the adequate safety margins. The factors influencing the most in the evolution are: duration of hearing deprivation, age at implantation, cochlear anatomy and functionality of the auditory pathway, patient's and relative's motivation, and the coexistence of other handicaps associated to hearing losses.

Speech perception with the ACE and the SPEAK speech coding strategies for children implanted with the Nucleus cochlear implant

OBJECTIVE

The aim of this study is to determine whether implanted children using the ACE speech coding strategy demonstrate superior performances compared to implanted children using the SPEAK speech coding strategy over time.

METHODS

Cochlear implanted children with prelinguistic sensorineural bilateral deafness of profound degree, using either the ACE or SPEAK coding strategy, were evaluated and compared. Both groups of children used one of the speech coding strategies continuously from the initial programming session and for a period of 2 years post-switch-on. One group comprised children who were retrospectively implanted and had received the SPEAK speech coding strategy (n=32) and the second group consisted of prospectively implanted children who received the ACE speech coding strategy (n=26). Both populations were homogenous as far as age of implantation, degree of hearing loss, anatomy of the cochlea, depth of electrode insertion, and educational and rehabilitative support provided. Children were assessed at 6, 12 and 24 months post switch-on via pure-tone audiometry and for speech perception tests. Children using the ACE speech coding strategy were additionally evaluated using the MAIS and MUSS language scales.

RESULTS

Satisfactory benefits in speech perception were demonstrated by both groups of implanted children. No significant difference between the mean pure tone thresholds was observed postoperatively between the groups. Two years post switch-on the group using the ACE speech coding strategy demonstrated superior results for vowel discrimination in comparison to children using the SPEAK coding strategy. No significant difference was observed between the groups for performance on discrimination of syllable patterns (ESP) or for disyllablic word recognition tests. Additionally, the group of ACE users demonstrated maximum performance on MAIS and MUSS scales, 2 years post switch-on.

CONCLUSIONS

The results clearly demonstrate significant benefit of cochlear implantation in prelinguistically deafened children for speech perception ability when using either the SPEAK or ACE speech coding strategies. Children using the ACE speech coding strategy demonstrate more rapid progress in improved speech perception ability initially, however 2 years post switch-on, no significant difference in performance on open-set speech recognition tests can be noted irrespective of the strategy in use.

The effect of age at cochlear implant initial stimulation on expressive language growth in infants and toddlers

This study examined the growth of expressive language skills in children who received cochlear implants (CIs) in infancy. Repeated language measures were gathered from 29 children who received CIs between 10 and 40 months of age. Both cross-sectional and growth curve analyses were used to assess the relationship between expressive language outcomes and CI experience. A beneficial effect of earlier implantation on expressive language growth was found. Growth curve analysis showed that growth was more rapid in children implanted as infants than those implanted as toddlers. Age at initial stimulation accounted for 14.6% of the variance of the individual differences in expressive language growth rates.

Is there a critical period for cochlear implantation in congenitally deaf children? Analyses of hearing and speech perception performance after implantation

A range of basic and applied studies have demonstrated that during the development of the auditory system, early experimental manipulations or clinical interventions are generally more effective than those made later. We present a short review of these studies. We investigated this age-related plasticity in relation to the timing of cochlear implantation in deaf-from-birth children. Cochlear implantation is a standard intervention for providing hearing in children with severe to profound deafness. An important practical question is whether there is a critical period or cutoff age of implantation after which hearing outcomes are significantly reduced. In this article, we present data from prelingually deaf children (mostly congenitally deaf) implanted at ages ranging from 1 to 15 years. Each child was tested with auditory and speech understanding tests before implantation, and at regular intervals up to 8 years postimplantation. We measured the improvement in performance of speech understanding tests in younger implanted children and compared it with the results of those implanted at a later age. We also used a binary partitioning algorithm to divide the data systematically at all ages at implant to determine the optimum split, i.e., to determine the age at implant which best separates performance of early implanted versus later implanted children. We observed distinct age-of-implant cutoffs, and will discuss whether these really represent critical periods during development.

Cochlear implantation in adults with prelingual deafness. Part I. Clinical results

OBJECTIVES/HYPOTHESIS

To examine the hypothesis that the newer generations of cochlear implants could provide considerable speech understanding to late-implanted, prelingually deaf adult patients.

STUDY DESIGN

Retrospective review.

METHODS

Speech perception scores of 103 patients with long-term prelingual deafness obtained from the recent clinical trials were compared with other previously published results.

RESULTS

Unlike patients receiving implants in early childhood, the audiologic performance of most patients with long-term prelingual deafness rapidly approached asymptotic levels within 1 year after implantation. Beginning at 3 months postimplantation, statistically significant improvement was noted in their speech perception scores compared with their preimplant levels. However, the average performance plateau achieved by this group of patients was significantly below the levels published for postlingual patients. No statistically significant differences were observed between the test scores at any testing interval among patients with different devices.

CONCLUSIONS

Most patients with long-term prelingual deafness achieve their performance plateau within 1 year after implantation. The results suggest that patient characteristics, rather than device properties, are likely to be the major contributing factor responsible for the observed audiologic outcomes.