Systematic Review on Late Cochlear Implantation in Early-Deafened Adults and Adolescents: Clinical Effectiveness.

OBJECTIVES: Cochlear implantation in early-deafened patients, implanted as adolescents or adults, is not always advised due to poor expected outcomes. In order to judge whether such reluctance is justified, the current systematic review aimed to gather all available evidence on postoperative outcomes obtained by early-deafened patients using a state-of-the art cochlear implant (CI). DESIGN: Five electronic databases (PubMed, Embase, the Cochrane library, CINAHL, and PsycInfo) were systematically searched for studies in English, French, German, or Dutch, published between 2000 and September 2017. Studies that reported pre- and postoperative outcomes on any measure of speech or sound perception, audiovisual or subjective benefit (quality of life) were included. Study quality was assessed with the Institute of Health Economics quality appraisal tool for case series studies. RESULTS: The systematic search and subsequent full-text evaluation identified 38 studies meeting the inclusion criteria. Only a limited number of studies were judged to be of high quality according to the Institute of Health Economics tool, with lack of (clear) presentation of relevant study information being a recurring problem. Twenty-five studies presented viable outcomes on open-set speech understanding in quiet: mean postoperative scores obtained with CI remained below 50% for the vast majority of studies; significant postoperative improvements were found in 16 studies, although this number might have been higher if appropriate statistical testing had been performed in all studies. Eight studies observed increased audiovisual performance after implantation, which was statistically significant in six studies. A validated measure of hearing-related quality of life was used in only 5 of the 16 studies assessing subjective outcomes, showing significant postoperative improvements for most questionnaire domains. The relation between auditory and subjective outcomes was assessed in two studies, with contradictory results. CONCLUSIONS: The current review showed that late cochlear implantation in early-deafened subjects resulted in significantly improved open-set speech perception, audiovisual speech perception, and (hearing-related) quality of life in the majority of the studies involved. Nonetheless, more and especially higher-quality research is needed in order to gain a more detailed understanding of the outcomes of cochlear implantation in this population.

Systematic Review on Late Cochlear Implantation in Early-Deafened Adults and Adolescents: Predictors of Performance.

OBJECTIVES: Early-deafened, late-implanted adolescents and adults constitute a unique group of cochlear implant (CI) users, showing a large variability in outcomes. The current systematic review aimed to determine which preimplantation factors are relevant in predicting postoperative outcomes in this patient group. DESIGN: A systematic search for studies published between 2000 and September 2017 was performed in five electronic databases (PubMed, Embase, the Cochrane library, CINAHL, and PsycInfo). Prognostic studies that assessed the relation between patient-related factors and CI outcomes in early-deafened but late-implanted adolescent and adult CI users were included. Study quality was assessed with the Quality In Prognosis Studies (QUIPS) tool. RESULTS: The systematic search and subsequent full-text evaluation identified 13 studies that had a clear prognostic study goal. Eight out of these 13 studies had a high risk of bias for at least one of the five QUIPS domains. Analysis of the outcomes identified that communication mode (in childhood), preoperative speech intelligibility, and preoperative speech recognition scores were significantly related to speech perception outcomes for this group of CI users. A number of additional factors considered worth for further investigation were also identified. CONCLUSIONS: The analysis of the studies assessing the effect of a number of patient-related factors on outcome with CI in early-deafened adolescents and adults identified three potential prognostic factors and a number of additional factors to be incorporated in future research. More high-quality prognosis studies in the investigated patient population are still needed.

Late Cochlear Implantation in Early-Deafened Adults: A Detailed Analysis of Auditory and Self-Perceived Benefits.

OBJECTIVES: It is known that early-deafened cochlear implant (CI) users are a very heterogeneously performing group. To gain more insight into this population, this study investigated (1) postoperative changes in auditory performance over time based on various outcome measures, focusing on poor performers, (2) self-perceived outcomes, (3) relations between auditory and self-perceived outcomes, and (4) preimplantation factors predicting postoperative outcomes. METHODS: Outcomes were assessed prospectively in a group of 27 early-deafened, late-implanted CI users, up to 3 years after implantation. Outcome measures included open-set word and sentence recognition, closed-set word recognition, speech tracking and a questionnaire on self-perceived outcomes. Additionally, the relative influence of 8 preimplantation factors on CI outcome was assessed with linear regression analyses. RESULTS: Significant improvements were found for auditory performance measures and most of the questionnaire domains. Significant changes of the closed-set word test, speech tracking and questionnaire were also found for a subgroup of poor performers. Correlations between auditory and self-perceived outcomes were weak and nonsignificant. Preoperative word recognition and preoperative hearing thresholds, both for the implanted ear, were significant predictors of postoperative outcome in the multivariable regression model, explaining 63.5% of the variation. CONCLUSIONS: Outcome measurement in this population should be adjusted to the patients' individual performance level and include self-perceived benefit. There is still a need for more knowledge regarding predictors of CI outcomes in this group, but the current study suggests the importance of the preoperative performance of the ear to be implanted.

Fitting prelingually deafened adult cochlear implant users based on electrode discrimination performance.

OBJECTIVE: This study investigated the hypotheses that (1) prelingually deafened CI users do not have perfect electrode discrimination ability and (2) the deactivation of non-discriminable electrodes can improve auditory performance. DESIGN: Electrode discrimination difference limens were determined for all electrodes of the array. The subjects' basic map was subsequently compared to an experimental map, which contained only discriminable electrodes, with respect to speech understanding in quiet and in noise, listening effort, spectral ripple discrimination and subjective appreciation. STUDY SAMPLE: Subjects were six prelingually deafened, late implanted adults using the Nucleus cochlear implant. RESULTS: Electrode discrimination difference limens across all subjects and electrodes ranged from 0.5 to 7.125, with significantly larger limens for basal electrodes. No significant differences were found between the basic map and the experimental map on auditory tests. Subjective appreciation was found to be significantly poorer for the experimental map. CONCLUSIONS: Prelingually deafened CI users were unable to discriminate between all adjacent electrodes. There was no difference in auditory performance between the basic and experimental map. Potential factors contributing to the absence of improvement with the experimental map include the reduced number of maxima, incomplete adaptation to the new frequency allocation, and the mainly basal location of deactivated electrodes.

Amplitude Modulation Detection and Speech Recognition in Late-Implanted Prelingually and Postlingually Deafened Cochlear Implant Users.

OBJECTIVES: Many late-implanted prelingually deafened cochlear implant (CI) patients struggle to obtain open-set speech understanding. Because it is known that low-frequency temporal-envelope information contains important cues for speech understanding, the goal of this study was to compare the temporal-envelope processing abilities of late-implanted prelingually and postlingually deafened CI users. Furthermore, the possible relation between temporal processing abilities and speech recognition performances was investigated. DESIGN: Amplitude modulation detection thresholds were obtained in eight prelingually and 18 postlingually deafened CI users, by means of a sinusoidally modulated broadband noise carrier, presented through a loudspeaker to the CI user's clinical device. Thresholds were determined with a two-down-one-up three-interval oddity adaptive procedure, at seven modulation frequencies. Phoneme recognition (consonant-nucleus-consonant [CNC]) scores (percentage correct at 65 dB SPL) were gathered for all CI users. For the prelingually deafened group, scores on two additional speech tests were obtained: (1) a closed-set monosyllable-trochee-spondee test (percentage correct scores at 65 dB SPL on word recognition and categorization of the suprasegmental word patterns), and (2) a speech tracking test (number of correctly repeated words per minute) with texts specifically designed for this population. RESULTS: The prelingually deafened CI users had a significantly lower sensitivity to amplitude modulations than the postlingually deafened CI users, and the attenuation rate of their temporal modulation transfer function (TMTF) was greater. None of the prelingually deafened CI users were able to detect modulations at 150 and 200 Hz. High and significant correlations were found between the results on the amplitude modulation detection test and CNC phoneme scores, for the entire group of CI users. In the prelingually deafened group, CNC phoneme scores, word scores on the monosyllable-trochee-spondee test, and speech tracking scores correlated significantly with the mean amplitude modulation detection threshold of the modulation frequencies between 5 and 100 Hz and with almost all separate amplitude modulation thresholds. High correlations with these speech measures were also found for the attenuation rate of and the surface area below the TMTF. In postlingually deafened CI users, CNC phoneme scores only correlated significantly with the 100-Hz and 150-Hz amplitude modulation thresholds, as well as with the attenuation rate of and surface area below the TMTF. CONCLUSIONS: Prelingually deafened CI users were less sensitive to temporal modulations than postlingually deafened CI users, and the attenuation rate of their TMTF was steeper. For all CI users, subjects with better amplitude modulation detection skills tended to score better on measures of speech understanding. Significant correlations with low modulation frequencies were found only for the prelingually deafened CI users and not for the postlingually deafened CI users.

Predictors of spoken language development following pediatric cochlear implantation.

OBJECTIVES: Although deaf children with cochlear implants (CIs) are able to develop good language skills, the large variability in outcomes remains a significant concern. The first aim of this study was to evaluate language skills in children with CIs to establish benchmarks. The second aim was to make an estimation of the optimal age at implantation to provide maximal opportunities for the child to achieve good language skills afterward. The third aim was to gain more insight into the causes of variability to set recommendations for optimizing the rehabilitation process of prelingually deaf children with CIs. DESIGN: Receptive and expressive language development of 288 children who received CIs by age five was analyzed in a retrospective multicenter study. Outcome measures were language quotients (LQs) on the Reynell Developmental Language Scales and Schlichting Expressive Language Test at 1, 2, and 3 years after implantation. Independent predictive variables were nine child-related, environmental, and auditory factors. A series of multiple regression analyses determined the amount of variance in expressive and receptive language outcomes attributable to each predictor when controlling for the other variables. RESULTS: Simple linear regressions with age at first fitting and independent samples t tests demonstrated that children implanted before the age of two performed significantly better on all tests than children who were implanted at an older age. The mean LQ was 0.78 with an SD of 0.18. A child with an LQ lower than 0.60 (= 0.78-0.18) within 3 years after implantation was labeled as a weak performer compared with other deaf children implanted before the age of two. Contralateral stimulation with a second CI or a hearing aid and the absence of additional disabilities were related to better language outcomes. The effect of environmental factors, comprising multilingualism, parental involvement, and communication mode increased over time. Three years after implantation, the total multiple regression model accounted for 52% of the variance in receptive language scores and 58% of the variance in expressive language scores. CONCLUSIONS: On the basis of language test scores of this large group of children, an LQ of 0.60 or lower was considered a risk criterion for problematic language development compared with other deaf children using CIs. Children attaining LQs below 0.60 should be monitored more closely and perhaps their rehabilitation programs should be reconsidered. Improved language outcomes were related to implantation under the age of two, contralateral stimulation, monolingualism, sufficient involvement of the parents, and oral communication by the parents. The presence of an additional learning disability had a negative influence on language development. Understanding these causes of variation can help clinicians and parents to create the best possible circumstances for children with CIs to acquire language.

Bimodal listeners are not sensitive to interaural time differences in unmodulated low-frequency stimuli (L).

Sensitivity to interaural time differences (ITDs) with unmodulated low-frequency stimuli was assessed in bimodal listeners who had previously shown to be good performers in ITD experiments. Two types of stimuli were used: (1) an acoustic sinusoid combined with an electric transposed signal and (2) an acoustic sinusoid combined with an electric clicktrain. No or very low sensitivity to ITD was found for these stimuli, even though subjects were highly trained on the task and were intensively tested in multiple test sessions. In previous studies with users of a cochlear implant (CI) and a contralateral hearing aid (HA) (bimodal listeners), sensitivity was shown to ITD with modulated stimuli with frequency content between 600 and 3600 Hz. The outcomes of the current study imply that in speech processing design for users of a CI in combination with a HA on the contralateral side, the emphasis should be more on providing salient envelope ITD cues than on preserving fine-timing ITD cues present in acoustic signals.

Sensitivity to interaural level difference and loudness growth with bilateral bimodal stimulation.

The interaural level difference (ILD) is an important cue for the localization of sound sources. The sensitivity to ILD was measured in 10 users of a cochlear implant (CI) in one ear and a hearing aid (HA) in the other severely impaired ear. For simultaneous presentation of a pulse train on the CI side and a sinusoid on the HA side the just noticeable difference (JND) in ILD and loudness growth functions were measured. The mean JND for pitch-matched electric and acoustic stimulation was 1.7 dB. A linear fit of the loudness growth functions on a decibel-versus-microampere scale shows that the slope depends on the subject's dynamic ranges.

Quality-of-life benefit from cochlear implantation in the elderly.

OBJECTIVE: To compare the audiologic results of geriatric patients receiving cochlear implants with younger age groups and to evaluate the quality of life after cochlear implantation in the geriatric population by means of validated quality-of-life questionnaires. STUDY DESIGN: Cross-sectional study involving 89 postlingually deafened cochlear implant subjects. SETTING: Tertiary referral center. PATIENTS: A total of 89 postlingually deafened patients were included in the study, among which were 25 patients who were aged 70 years or older. INTERVENTIONS: All patients received a cochlear implant. Subjects were implanted with either the Laura, Nucleus 24, or Med-el Combi 40+ cochlear implant systems implementing the SPEAK, ACE, CIS, or CIS+ coding strategies. MEAN OUTCOME MEASURES: Speech recognition was determined by means of phonetically balanced monosyllabic word lists. The Hearing Handicap Inventory for Adults, the Glasgow Benefit Inventory, and the scale for the prediction of hearing disability in sensorineural hearing loss were used to quantify the quality of life. RESULTS: Mean audiologic performance for the three groups increased significantly after implantation (p < 0.001). Postoperative audiologic performance of the geriatric population led to useful hearing, but these scores were significantly lower than for the younger age groups (p = 0.002). However, the quality-of-life outcomes for the geriatric group were similar to those of the younger age groups (p = 0.411 for the Hearing Handicap Inventory for Adults; p = 0.886 for the Glasgow Benefit Inventory). CONCLUSION: The results of this study prove that cochlear implantation in the elderly provides improvements in quality of life and speech understanding, similar to those for younger adult cochlear implant recipients.

Bilateral cochlear implantation in children.

AIMS: to determine the benefit of bilateral cochlear implantation in a child on speech and language development. METHOD: This child got her first implant, a Nucleus 24-system, on the right side at the age of 2.5 years. The left side was implanted at the age of 4.4 years with a Nucleus 24Contour-system. On the right side she's now wearing an Esprit 24-speechprocessor (SPR). On the left side she has a Sprint-SPR. M. goes to a mainstream school and receives Speech and Language therapy in a Speech and Hearing Rehab Centre. The etiology of her deafness was hyperbilirubinemia. Auditory capacity and speech recognition tests were performed for both ears separately and together. RESULTS: Aided thresholds give a PTA of 28 dBA with the first implant, 22 dBA with the second implant and with both implants we get a PTA of 23 dBA. Results for speech identification and recognition demonstrated an increased performance when both implants are used together. Speech and language development was equivalent to the mean of age 4.5. At the time of testing M. was 4.8 years. At this time the speech and language development show no delays with normal hearing children. CONCLUSIONS: bilateral cochlear implantation in children may have additional value for their speech and language development. Also, implantation may be considered when auditory neuropathy is likely.

Noninvasive treatment alternative for intractable startle epilepsy.

We describe a treatment alternative for intractable, startle-provoked, epileptic seizures in four children aged between 8 and 14. Three of the four children had symptomatic localization-related epilepsy. They all suffered from intractable epilepsy precipitated by sudden sounds. The fact that seizures tended to occur with high frequency - more than one seizure a day - had a clear impact on daily life. Clinical seizure pattern demonstrated asymmetric tonic posturing in all four children. Three children experienced several seizure types including focal seizure onset. All children had focal neurological signs or learning disabilities or a combination of both. Our noninvasive treatment method using psychoeducational counseling and sound generators was applied in four children, resulting in a seizure frequency reduction of ≥ 50% in two of them.

Auditory maturation in premature infants: a potential pitfall for early cochlear implantation.

OBJECTIVES/HYPOTHESIS: To describe spontaneous hearing improvement in the first years of life of a number of preterm neonates relative to cochlear implant candidacy. STUDY DESIGN: Retrospective case study. METHODS: Hearing levels of 14 preterm neonates (mean gestational age at birth = 29 weeks) referred after newborn hearing screening were evaluated. Initial hearing thresholds ranged from 40 to 105 dBHL (mean = 85 dBHL). RESULTS: Hearing level improved to normal levels for four neonates and to moderate levels for five, whereas for five neonates, no improvement in hearing thresholds was observed and cochlear implantation was recommended. Three of the four neonates in whom the hearing improved to normal levels were born prior to 28 weeks gestational age. Hearing improvement was mainly observed prior to a gestational age of 80 weeks. CONCLUSIONS: Delayed maturation of an immature auditory pathway might be an important reason for referral after newborn hearing screening in premature infants. Caution is advised regarding early cochlear implantation in preterm born infants. Audiological follow-ups until at least 80 weeks gestational age are therefore recommended.

Effect of pediatric bilateral cochlear implantation on language development.

OBJECTIVE: To examine spoken language outcomes in children undergoing bilateral cochlear implantation compared with matched peers undergoing unilateral implantation. DESIGN: Case-control, frequency-matched, retrospective cross-sectional multicenter study. SETTING: Two Belgian and 3 Dutch cochlear implantation centers. PARTICIPANTS: Twenty-five children with 1 cochlear implant matched with 25 children with 2 cochlear implants selected from a retrospective sample of 288 children who underwent cochlear implantation before 5 years of age. INTERVENTION: Cochlear implantation. MAIN OUTCOME MEASURES: Performance on measures of spoken language comprehension and expression (Reynell Developmental Language Scales and Schlichting Expressive Language Test). RESULTS: On the receptive language tests (mean difference [95% CI], 9.4 [0.3-18.6]) and expressive language tests (15.7 [5.9-25.4] and 9.7 [1.5-17.9]), children undergoing bilateral implantation performed significantly better than those undergoing unilateral implantation. Because the 2 groups were matched with great care on 10 auditory, child, and environmental factors, the difference in performance can be mainly attributed to the bilateral implantation. A shorter interval between both implantations was related to higher standard scores. Children undergoing 2 simultaneous cochlear implantations performed better on the expressive Word Development Test than did children undergoing 2 sequential cochlear implantations. CONCLUSIONS: The use of bilateral cochlear implants is associated with better spoken language learning. The interval between the first and second implantation correlates negatively with language scores. On expressive language development, we find an advantage for simultaneous compared with sequential implantation.

Clinical evaluation of cochlear implant sound coding taking into account conjectural masking functions, MP3000™.

Efficacy of the SPEAK and ACE coding strategies was compared with that of a new strategy, MP3000™, by 37 European implant centers including 221 subjects. The SPEAK and ACE strategies are based on selection of 8-10 spectral components with the highest levels, while MP3000 is based on the selection of only 4-6 components, with the highest levels relative to an estimate of the spread of masking. The pulse rate per component was fixed. No significant difference was found for the speech scores and for coding preference between the SPEAK/ACE and MP3000 strategies. Battery life was 24% longer for the MP3000 strategy. With MP3000 the best results were found for a selection of six components. In addition, the best results were found for a masking function with a low-frequency slope of 50 dB/Bark and a high-frequency slope of 37 dB/Bark (50/37) as compared to the other combinations examined of 40/30 and 20/15 dB/Bark. The best results found for the steepest slopes do not seem to agree with current estimates of the spread of masking in electrical stimulation. Future research might reveal if performance with respect to SPEAK/ACE can be enhanced by increasing the number of channels in MP3000 beyond 4-6 and it should shed more light on the optimum steepness of the slopes of the masking functions applied in MP3000.

Sensitivity to interaural time differences with combined cochlear implant and acoustic stimulation.

The interaural time difference (ITD) is an important cue to localize sound sources. Sensitivity to ITD was measured in eight users of a cochlear implant (CI) in the one ear and a hearing aid (HA) in the other severely impaired ear. The stimulus consisted of an electric pulse train of 100 pps and an acoustic filtered click train. Just-noticeable differences (JNDs) in ITD were measured using a lateralization paradigm. Four subjects exhibited median JNDs in ITD of 156, 341, 254, and 91 mus; the other subjects could not lateralize the stimuli consistently. Only the subjects who could lateralize had average acoustic hearing thresholds at 1,000 and 2,000 Hz better than 100-dB SPL. The electric signal had to be delayed by 1.5 ms to achieve synchronous stimulation at the auditory nerves.

The ASSR: clinical application in normal-hearing and hearing-impaired infants and adults, comparison with the click-evoked ABR and pure-tone audiometry.

The objective of this study was to investigate the clinical application of the ASSR (GSI Audera). It was completed in two parts: Study 1. Correlation between the ASSR-based threshold estimations and the conventional pure-tone thresholds in adults; and Study 2. Correlation between the average of the 2-4 kHz ASSR-based threshold estimations and c-ABR thresholds in children. The ASSRs were recorded in awake adults and sleeping infants with a range of hearing loss at CFs of 0.5 to 4 kHz and MFs between 46 and 95 Hz. The results show that in hearing-impaired adults (thresholds > 40 dBHL) good correlations can be observed between the behavioural thresholds and the ASSR-based threshold estimations. For the normal- to near-normal-hearing adults, a significant correspondence exists between the ASSR-based threshold estimations and FPTA. In children, strong correlations were found between the c-ABR and the 2-4 kHz ASSR-based threshold estimation average. These studies illustrate that the GSI Audera ASSR can accurately predict the behavioural audiogram in hearing-impaired subjects. In subjects with normal hearing the individual ASSR-based threshold estimations scatter too much. Instead the average of the ASSR-based threshold estimations corresponds well with the FPTA.