Otology & Neurotology - Highlights from the ACIA 15th Symposium on Cochlear Implants in Children in San Francisco

Introduction to the Special Issue: 15th Symposium on Cochlear Implants in Children No abstract available

Relationship Between Objective and Behavioral Audiology for Young Children Being Assessed for Cochlear Implantation: Implications for CI Candidacy Assessment Objective: This study aimed to evaluate the feasibility of making cochlear implant recommendations based on diagnostic ABR and ASSR results. The goal was to challenge the need for behavioral audiometry as part of the standard cochlear implant assessment battery for infants with profound hearing loss and to reduce the age at which cochlear implant recommendation was made. Study Design: A retrospective review of 123 patient files for children referred to the pediatric cochlear implant service before 3 years of age over a 3-year period was undertaken. Results for click-ABR, ASSR, and behavioral audiology at 500, 1k, 2k and 4k Hz, and tympanometry were collected and relationships were investigated for 64 children who met the inclusion criteria. Data were excluded for 59 children due to the presence of auditory neuropathy findings, middle ear pathology at the time of testing, if ASSR was not assessed at intensity levels >85 dB, and/or behavioral testing was judged to be unreliable by two experienced clinicians. Setting: Primary care pediatric cochlear implant program located within a hospital setting. Patients: Pediatric patients referred for cochlear implant evaluation before 3 years of age. Interventions(s): Children were assessed using ABR, ASSR, and behavioral audiometry for identification and confirmation of hearing loss. Main Outcome Measures(s): Correlation between diagnostic click-ABR and ASSR thresholds and subsequently obtained behavioral hearing thresholds. Results: Results for objective measures (click-ABR and ASSR) were significantly correlated with behavioral results. The correlations, however, were poorer than expected with limited predictive value. For 6 of the 64 children click-ABR and/or ASSR suggested profound hearing loss and corresponding behavioral hearing threshold was found to be in the severe hearing loss range. Conclusions: Findings of this study do not support making cochlear implant recommendations based on the findings of diagnostic click-ABR and ASSR alone. Investigating ways to reduce the average age children with severe-to-profound hearing loss receive a cochlear implant is a priority for the study institution. An alternate evaluation pathway for infants which incorporates a multifaceted assessment is warranted and will be the focus of future work at the study institution.

Remote Programming of Cochlear Implants Objective: This study investigated the safety and efficacy of remote programming of cochlear implants. Study Design: Single-subject design Setting: Four North American clinical sites Patients: Forty cochlear implant recipients aged 12 years or older Intervention: Subjects had their cochlear implants programmed at a location that was remote from their audiologist using telecommunication with and without the support of a facilitator. Main Outcome Measures: Consonant-Nucleus-Consonant (CNC) word scores and the Speech, Spatial, and Qualities of Hearing Scale-C (SSQ-C) were compared using the subject's in-office MAP (program) and MAPs programmed remotely with and without the assistance of a facilitator. Additional subjective preference data were gathered from subjects and audiologists via questionnaires. Results: MAPs programmed via the three different models did not yield significantly different group mean CNC word scores. No device/procedure-related adverse events occurred. SSQ-C questionnaire results indicated that recipients received similar subjective benefit from familiar in-office, remote-facilitated, and remote-unassisted MAPs. Conclusions: Remote programming is an effective means of cochlear implant service delivery. The practice was approved by the FDA on November 17, 2017 supported by the results of this study.

Bilateral Cochlear Implants Using Two Electrode Lengths in Infants With Profound Deafness Objective: The goal of this investigation was to determine if a short electrode in one ear and standard electrode in the contralateral ear could be an option for infants with congenital profound deafness to theoretically preserve the structures of the inner ear. Similarities in performance between ears and compared with a control group of infants implanted with bilateral standard electrodes was evaluated. Study Design: Repeated-measure, single-subject experiment. Setting: University of Iowa—Department of Otolaryngology. Participants: Nine infants with congenital profound bilateral sensorineural hearing loss. Intervention(s): Short and standard implants. Main Outcome Measure(s): Early speech perception test (ESP), children's vowel, phonetically balanced-kindergarten (PB-K) word test, and preschool language scales-3 (PLS-3). Results: ESP scores showed performance reaching a ceiling effect for the individual short and standard ears and bilaterally. The children's vowel and PB-K word results indicated significant (both p < 0.001) differences between the two ears. Bilateral comparisons to age-matched children with standard bilateral electrodes showed no significant differences (p = 0.321) in performance. Global language performance for six children demonstrated standard scores around 1 standard deviation (SD) of the mean. Two children showed scores below the mean, but can be attributed to inconsistent device usage. Averaged total language scores between groups showed no difference in performance (p = 0.293). Conclusions: The combined use of a short electrode and standard electrode might provide an option for implantation with the goal of preserving the cochlear anatomy. However, further studies are needed to understand why some children have or do not have symmetric performance.

Hearing Preservation in Pediatric Recipients of Cochlear Implants Objective: To determine factors that influence low-frequency hearing preservation following pediatric cochlear implantation and compare hearing preservation outcomes between 20 and 24 mm depth lateral wall electrodes. Study Design: Retrospective chart review. Setting: Tertiary academic referral center. Patients: Pediatric cochlear implant recipients (under the age of 18) who presented preoperatively with a low-frequency pure tone average (LFPTA; 125, 250 and 500 Hz) ≤ 70 dB HL. Intervention: Cochlear implantation Main Outcome Measures: Multiple logistic regression evaluating the influence of variables on change in LFPTA including preoperative low-frequency hearing, lateral wall or perimodiolar electrode, progressive vs stable hearing, side, time from surgery, and the presence or the absence of enlarged vestibular aqueduct. A second analysis reviews the 12-month postactivation hearing preservation of a subset of subjects implanted with modern lateral wall electrodes. Results: A total of 105 subjects were included from the last 10 years for our multiple logistic regression analysis. This demonstrated a significant correlation of poorer preoperative low-frequency hearing with change in LFPTA. A significant negative effect of electrode type, specifically perimodiolar electrodes was also seen. Forty-five subjects from the last 3 years undergoing cochlear implantation with a lateral wall electrode demonstrated an overall 12-month preservation rate (LFPTA < 90 dB) of 82%. Differences in preservation rates existed between different electrodes. Conclusion: Preservation of low-frequency hearing following cochlear implantation is predicted both by preoperative low-frequency hearing as well as type of electrode implanted. Consistent low-frequency hearing preservation is possible in pediatric subjects receiving lateral wall electrodes, although differences exist between electrode types.

Hybrid Music Perception Outcomes: Implications for Melody and Timbre Recognition in Cochlear Implant Recipients Objective: To examine whether or not electric–acoustic music perception outcomes, observed in a recent Hybrid L24 clinical trial, were related to the availability of low-frequency acoustic cues not present in the electric domain. Study Design: Prospective, repeated-measures, within-subject design. Setting: Academic research hospital. Subjects: Nine normally hearing individuals. Intervention: Simulated electric–acoustic hearing in normally hearing individuals. Main Outcomes Measures: Acutely measured melody and timbre recognition scores from the University of Washington Clinical Assessment of Music Perception (CAMP) test. Results: Melody recognition scores were consistently better for listening conditions that included low-frequency acoustic information. Mean scores for both acoustic (73.5%, S.D. = 15.5%) and electric–acoustic (67.9%, S.D. = 21.2%) conditions were significantly better (p < 0.001) than electric alone (39.2%, S.D. = 18.1%). This was not the case for timbre recognition for which scores were more variable across simulated listening modes with no significant differences found in mean scores across electric (36.1%, S.D. = 17.7%), acoustic (38.0%, S.D. = 20.4%), and electric–acoustic (40.7%, S.D. = 19.7%) conditions (p > 0.05). Conclusion: Recipients of hybrid cochlear implants demonstrate music perception abilities superior to those observed in traditional cochlear implant recipients. Results from the present study support the notion that electric–acoustic stimulation confers advantages related to the availability of low-frequency acoustic hearing, most particularly for melody recognition. However, timbre recognition remains more limited for both hybrid and traditional cochlear implant users. Opportunities remain for new coding strategies to improve timbre perception.

Beyond Technology: The Interaction of Perceptual Accuracy and Experiential Factors in Pediatric Music Engagement Background: Music engagement (the active making of music, e.g., music lessons and ensembles) is a common part of educational and community experiences. Music making typically involves listening to and production of rapidly changing combinations of pitch, timbre, and rhythm, which can be challenging for cochlear implant (CI) recipients, given that pitch and timbre are poorly conveyed through the CI. Pediatric CI users have variable patterns of music engagement, but some have achieved, sustained participation despite the degraded CI signal. What factors contribute to their persistence in these demanding listening situations? Our study examined a cohort of pediatric CI recipients from our center to better understand those perceptual and experiential factors most influential in relation to music engagement. Method: Regressions and correlations were run for measures of pitch and speech perception, hearing history, familial involvement in music, personal importance of music, and extent of music engagement (years in music lessons; general involvement in music). Results: Pitch ranking accuracy was a significant predictor of sustained participation in music lessons (p = 0.0019), and sustained involvement in music (p = 0.0038), as well as performance on CNC words (p = −0.0060) and phonemes (p = −0.0174). Extent of familial involvement in music at the time of testing was significantly predictive of the user's musical engagement (p = 0.0007). Personal importance of music was not predicted by or significantly correlated with, any of the variables investigated. Conclusion: Better pitch perception was associated with sustained involvement in music lessons as well as better speech perception. However, familial involvement in music was of greater impact for sustained music engagement. Judicious choice of musical instrument also influenced persistence. The positive impact of familial involvement indicates that perceptual limitations associated with CI processing do not present insurmountable barriers to music engagement. Because music engagement provides normalizing social involvement and challenging auditory practice, the impact of parental involvement has implications for counseling parents of CI users.

Comparison of Skull Radiograph and Computed Tomography Measurements of Cochlear Implant Insertion Angles Background: Measurement of the angular depth of insertion (aDOI) of cochlear implant electrode arrays has numerous clinical and research applications. Plain-film radiographs are easily obtained intraoperatively and have been described as a means to calculate aDOI. CT imaging with 3D reformatting can also be used for this measurement, but is less conveniently obtained and requires higher radiation doses, a particular concern in pediatrics. The extent to which plain-film and 3D CT image-based measurements are representative of the true position of the electrode within the cochlea is unknown. Methods: Cochlear implantation was performed on 10 cadaveric temporal bones. Five bones were implanted with perimodiolar electrodes (Contour Advance TM, Cochlear, Sydney, Australia) and five were implanted with lateral wall electrodes (Slim Straight, Cochlear). The insertion depths of the electrodes were varied. Each bone was imaged with a radiograph and CT. aDOI was measured for each bone in each imaging modality by a neurotologist and a neuroradiologist. To obtain a "gold standard" estimate of aDOI, the implanted temporal bones were embedded in an epoxy resin and methodically sectioned at 100 μm intervals; histologic images were captured at each interval. A 3D stack of the images was compounded, and a MATLAB script used to calculate aDOI of the most apical electrode. Measurements in the three modalities (radiograph, CT, and histology) were then compared. Results: The average aDOI across all bones was similar for all modalities: 423° for radiographs, 425° for CT scans, and 427° for histology, indicating that neither imaging modality resulted in large systematic errors. Using the histology-measured angles as a reference, the average error for CT-based measures (regardless of whether the error was in the positive or negative direction) was 12°, and that for radiograph-based measures was 15°. This small difference (12 vs 15° error) was not statistically significant. Conclusion: Based on this cadaveric temporal bone model, both radiographs and CTs can provide reasonably accurate aDOI measurements. In this small sample, and as expected, the CT-based estimates were more accurate than the radiograph-based measurements. However, the difference was small and not statistically significant. Thus, the use of plain radiographs to calculate aDOI seems judicious whenever it is desired to prevent unnecessary radiation exposure and expense.

Surgical Experience and Early Outcomes With a Slim Perimodiolar Electrode Introduction: In 2016 the Cochlear CI532 received FDA approval and has since been the primary full-length electrode from this manufacturer implanted at our center. Our experience to date including surgical technique and early patient outcomes are reviewed here. Methods: Since 2016, this array was used as our standard full length Cochlear array, including children with normal anatomy, with 237 total implantations. Surgical experience and clinical outcomes including low frequency hearing preservation and speech perception on CNC words were analyzed in those with at least 6 months follow-up implanted through June 2017 (n = 94). Results: Speech perception scores are improving over clinical follow-up in accord with other electrode arrays. Hearing preservation is possible with a number of patients utilizing acoustic low frequency hearing in conjunction with electric stimulation from their CI. Tip fold overs were infrequent (4.6%) and always identified on intraoperative x-ray. No patients left the operating room with a tip fold over. Conclusions: Speech perception outcomes with the CI532 slim periomodiolar array are similar to other full length arrays with the added potential for at least short term preservation of residual acoustic hearing. There is a learning curve to its use and intraoperative x-rays are valuable to ensure optimal placement.

Temporal Modulation Detection in Children and Adults With Cochlear Implants: Initial Results Objectives: The auditory experience of early deafened pediatric cochlear implant (CI) users is different from that of postlingually deafened adult CI users due to disparities in the developing auditory system. It is therefore expected that the auditory psychophysical capabilities between these two groups would differ. In this study, temporal resolving ability was investigated using a temporal modulation detection task to compare the performance outcomes between these two groups. Design: The minimum detectable modulation depth of amplitude modulated broadband noise at 100 Hz was measured for 11 early deafened children with a CI and 16 postlingually deafened adult CI users. Results: Amplitude modulation detection thresholds were significantly lower (i.e., better) for the pediatric CI users than for the adult CI users. Within each group, modulation detection thresholds were not significantly associated with chronologic age, age at implantation, or years of CI experience. Conclusions: Early implanted children whose auditory systems develop in response to electric stimulation demonstrate better temporal resolving abilities than postlingually deafened adult CI users. This finding provides evidence to suggest that early implanted children might benefit from sound coding strategies emphasizing temporal information.

Alexandros Sfakianakis
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alsfakia@gmail.com