Outcomes In Cochlear Implant Recipients Research Articles

How Can We Compare Cochlear Implant Systems across Manufacturers? A Scoping Review of Recent Literature.

Electric stimulation via a cochlear implant (CI) enables people with severe-to-profound sensorineural hearing loss to regain speech understanding and music appreciation and, thus, allow them to actively engage in social life. Three main manufacturers (CochlearTM, MED-ELTM, and Advanced BionicsTM "AB") have been offering CI systems, thus challenging CI recipients and otolaryngologists with a difficult decision as currently no comprehensive overview or meta-analysis on performance outcomes following CI implantation is available. The main goals of this scoping review were to (1) map the literature on speech and music performance outcomes and to (2) find whether studies have performed outcome comparisons between devices of different manufacturers. To this end, a literature search was conducted to find studies that address speech and music outcomes in CI recipients. From a total of 1592 papers, 188 paper abstracts were analyzed and 147 articles were found suitable for an examination of full text. From these, 42 studies were included for synthesis. A total of 16 studies used the consonant-nucleus-consonant (CNC) word recognition test in quiet at 60 db SPL. We found that aside from technical comparisons, very few publications compared speech outcomes across manufacturers of CI systems. However, evidence suggests that these data are available in large CI centers in Germany and the US. Future studies should therefore leverage large data cohorts to perform such comparisons, which could provide critical evaluation criteria and assist both CI recipients and otolaryngologists to make informed performance-based decisions.

Cochlear Implant Upper Stimulation Levels: eSRT vs. Loudness Scaling.

To assess the difference in speech recognition and sound quality between programming upper stimulation levels using behavioral measures (loudness scaling) and electrically evoked stapedial reflex thresholds (eSRTs). Double-blinded acute comparison study. Cochlear implant (CI) program at a tertiary medical center. Eighteen adult (mean age = 60 years) CI users and 20 ears. Speech recognition scores and sound quality ratings. Mean word and sentence in noise recognition scores were 8 and 9 percentage points higher, respectively, for the eSRT-based map. The sound quality rating was 1.4 points higher for the eSRT-based map. Sixteen out of 20 participants preferred the eSRT-based map. Study results show significantly higher speech recognition and more favorable sound quality using an eSRT-based map compared with a loudness-scaling map using a double-blinded testing approach. Additionally, results may be understated as 18 of 20 ears had eSRTs measured before study enrollment. Results underscore the importance of incorporating eSRTs into standard clinical practice to promote best outcomes for CI recipients.

Round Window Electrocochleography to Low Frequency Tones in Pediatric Cochlear Implant Recipients with and Without Auditory Neuropathy Spectrum Disorder: Separating Hair Cell and Neural Contributions Using a Computational Model.

Characterize the contribution of the auditory nerve neurophonic (ANN) to electrocochleography (ECochG) of pediatric cochlear implant (CI) recipients with and without auditory nerve spectrum disorder (ANSD). ECochG is an emerging technique for predicting outcomes in CI recipients. Its utility may be increased by separating the cochlear microphonic (CM), produced by hair cells, from the ANN, the evoked potential correlate of neural phase-locking, which are mixed in the ongoing portion of the response to low frequency tone bursts. Responses to tone bursts of different frequency and intensities were recorded from the round window of pediatric CI recipients. Separation of the CM and ANN was performed using a model of the underlying processes that lead to the shapes of the observed waveforms. Preoperative mean pure tone amplitudes of the included ANSD (n = 36) and non-ANSD subjects (n = 123), were similar (89.5 and 93.5, p = 0.1). Total of 1,024 ECochG responses to frequency and intensity series were recorded. The mean correlation ( r ) between the input and the modeled signals was 0.973 ± 0.056 (standard deviation). The ANN magnitudes were higher in the ANSD group (ANOVAs, F = 26.5 for frequency and 21.9 for intensity, df's = 1, p 's < 0.001). However, its relative contribution to the overall signal was lower (ANOVAs, F = 25.8 and 12.1, df = 1, p 's < 0.001). ANN was detected in low frequency ECochG responses but not high frequency responses in both ANSD and non-ANSD subjects. ANSD subjects, evidence of neural contribution in responses to low frequency stimuli was highly variable and often comparable to signals recorded in non-ANSD subjects. The computational model revealed that on average the ANN comprised a lower proportion of the overall signal than in non-ANSD subjects.

Review of Speech Outcomes in Cochlear Implant Recipients at a Nascent Cochlear Implant Program.

Introduction: The use of cochlear implantation to rehabilitate moderate to profound sensorineural hearing loss has become more widespread; however, the adult utilization rate of cochlear implant candidates is still very less. The study aims to examine the percentage of adult patients in a heterogeneous group of cochlear implant recipients at a nascent cochlear implant program who demonstrate improvements in speech outcomes.Methods: Speech outcome scores were assessed preoperatively and postoperatively at three, six, and 12-month intervals using consonant-nucleus-consonant (CNC) words and AzBio sentences in quiet. Mean speech outcome scores at each time point and binomial distribution tables with 95% CI were used to assess individual improvement in speech understanding.Results: 45 patients underwent a total of 49 cochlear implantation surgeries. The mean age at surgery was 62 years. The mean preoperative CNC score in the ear to be implanted was 18%±18, while the mean postoperative CNC score at three, six, and 12 months was 35%±21, 44%±23, and 45%±25, respectively. The mean preoperative AzBio score in the ear to be implanted was 22%±26 while the mean postoperative AzBio score at three, six, and 12 months was 50%±29, 56%±27, and 63%±26, respectively. Of the implantations, 74% (32 of 43) and 69% (22 of 32) showed significant improvement at six months or one year using AzBio and CNC binomial distribution tables, respectively.Conclusions: Findings demonstrate significant improvements in speech perception following cochlear implantation for patients not benefiting from hearing aid aural rehabilitation. The study provides realistic expectations for new and emerging programs hoping to demonstrate cochlear implant utility for improving patients’ speech outcomes.

Long-Term Vestibular Outcomes in Cochlear Implant Recipients.

Background: Vestibular dysfunction is likely the most common complication to cochlear implantation (CI) and may, in rare cases, result in persistent severe vertigo. Literature on long-term vestibular outcomes is scarce.Objective: This paper aims to evaluate vestibular dysfunction before and after cochlear implantation, the long-term vestibular outcomes, and follows up on previous findings of 35 consecutive adult cochlear implantations evaluated by a battery of vestibular tests.Methods: A prospective observational longitudinal cohort study was conducted on 35 CI recipients implanted between 2018 and 2019; last follow-up was conducted in 2021. At the CI work-up (T0) and two postoperative follow-ups (T1 and T2), 4 and 14 months following implantation, respectively, all patients had their vestibular function evaluated. Evaluation with a vestibular test battery, involving video head impulse test (vHIT), cervical vestibular evoked myogenic potentials (cVEMP), caloric irrigation test, and dizziness handicap inventory (DHI), were performed at all evaluations.Results: vHIT testing showed that 3 of 35 ears had abnormal vHIT gain preoperatively, which increased insignificantly to 4 of 35 at the last follow-up (p = 0.651). The mean gain in implanted ears decreased insignificantly from 0.93 to 0.89 (p = 0.164) from T0 to T2. Preoperatively, 3 CI ears had correction saccades, which increased to 11 at T2 (p = 0.017). Mean unilateral weakness increased from 19 to 40% from T0 to T2 (p < 0.005), and the total number of patients with either hypofunctioning or areflexic semicircular canals increased significantly from 7 to 17 (p < 0.005). Twenty-nine percent of CI ears showed cVEMP responses at T0, which decreased to 14% (p = 0.148) at T2. DHI total mean scores increased slightly from 10.9 to 12.8 from T0 to T1 and remained at 13.0 at T2 (p = 0.368). DHI scores worsened in 6 of 27 patients and improved in 4 of 27 subjects from T0 to T2.Conclusion: This study reports significant deterioration in vestibular function 14 months after cochlear implantation, in a wide range of vestibular tests. vHIT, caloric irrigation, and cVEMP all measured an overall worsening of vestibular function at short-term postoperative follow-up. No significant deterioration or improvement was measured at the last postoperative follow-up; thus, vestibular outcomes reached a plateau. Despite vestibular dysfunction, most of the patients report less or unchanged vestibular symptoms.

Objective Vestibular Test Battery and Patient Reported Outcomes in Cochlear Implant Recipients.

Cochlear implantation (CI) may have undesired effects on the vestibular apparatus. However, the literature holds no consensus on vestibular affection and the testing tools applied to test for vestibular dysfunction after cochlear implantation are inconsistent. We aimed to investigate the impact of CI on vestibular function by an extensive test battery including patient-reported outcomes. Prospective observational study. University hospital. Forty adult unilateral first-time CI recipients. Vestibular function was evaluated pre- and post-implantation with the video head impulse test (VHIT), the caloric test and cervical vestibular evoked myogenic potentials (cVEMPs), and the patient-reported dizziness handicap inventory (DHI). Mean VHIT gain decreased from preoperative 0.92 to 0.84 postoperative (p = 0.018); mean caloric unilateral weakness increased from 20.5% preoperative to 42.9% postoperative (p < 0.0001); cVEMP responses were present on 10 operated ears preoperative and five ears postoperative, and compared with non-implanted ears, cVEMP responses on implanted ears were impaired (p = 0.023). 50% of patients reported early postoperative dizziness, but the mean DHI score remained unchanged (p = 0.94). The DHI scores correlated poorly with the objective outcomes (rs = 0.19 and rs = -0.22). Vestibular function is significantly affected after cochlear implantation, but vestibular hypofunction varies with the test used. Although early dizziness after implantation is common, later DHI scores are not significantly higher than before the implantation, indicating that central compensation plays a major role for these patients.

Frequency-to-Place Mismatch: Characterizing Variability and the Influence on Speech Perception Outcomes in Cochlear Implant Recipients.

The spatial position of a cochlear implant (CI) electrode array affects the spectral cues provided to the recipient. Differences in cochlear size and array length lead to substantial variability in angular insertion depth (AID) across and within array types. For CI-alone users, the variability in AID results in varying degrees of frequency-to-place mismatch between the default electric frequency filters and cochlear place of stimulation. For electric-acoustic stimulation (EAS) users, default electric frequency filters also vary as a function of residual acoustic hearing in the implanted ear. The present study aimed to (1) investigate variability in AID associated with lateral wall arrays, (2) determine the subsequent frequency-to-place mismatch for CI-alone and EAS users mapped with default frequency filters, and (3) examine the relationship between early speech perception for CI-alone users and two aspects of electrode position: frequency-to-place mismatch and angular separation between neighboring contacts, a metric associated with spectral selectivity at the periphery. One hundred one adult CI recipients (111 ears) with MED-EL Flex24 (24 mm), Flex28 (28 mm), and FlexSOFT/Standard (31.5 mm) arrays underwent postoperative computed tomography to determine AID. A subsequent comparison was made between AID, predicted spiral ganglion place frequencies, and the default frequency filters for CI-alone (n = 84) and EAS users (n = 27). For CI-alone users with complete insertions who listened with maps fit with the default frequency filters (n = 48), frequency-to-place mismatch was quantified at 1500 Hz and angular separation between neighboring contacts was determined for electrodes in the 1 to 2 kHz region. Multiple linear regression was used to examine how frequency-to-place mismatch and angular separation of contacts influence consonant-nucleus-consonant (CNC) scores through 6 months postactivation. For CI recipients with complete insertions (n = 106, 95.5%), the AID (mean ± standard deviation) of the most apical contact was 428° ± 34.3° for Flex24 (n = 11), 558° ± 65.4° for Flex28 (n = 48), and 636° ± 42.9° for FlexSOFT/Standard (n = 47) arrays. For CI-alone users, default frequency filters aligned closely with the spiral ganglion map for deeply inserted lateral wall arrays. For EAS users, default frequency filters produced a range of mismatches; absolute deviations of ≤ 6 semitones occurred in only 37% of cases. Participants with shallow insertions and minimal or no residual hearing experienced the greatest mismatch. For CI-alone users, both smaller frequency-to-place mismatch and greater angular separation between contacts were associated with better CNC scores during the initial 6 months of device use. There is significant variability in frequency-to-place mismatch among CI-alone and EAS users with default frequency filters, even between individuals implanted with the same array. When using default frequency filters, mismatch can be minimized with longer lateral wall arrays and insertion depths that meet the edge frequency associated with residual hearing for CI-alone and EAS users, respectively. Smaller degrees of frequency-to-place mismatch and decreased peripheral masking due to more widely spaced contacts may independently support better speech perception with longer lateral wall arrays in CI-alone users.

Effect of Cochlear Implantation on Quality of Life in Adults with Unilateral Hearing Loss

Objective: Patients with moderate-to-profound sensorineural hearing loss in 1 ear and normal hearing in the contralateral ear, known as unilateral hearing loss (UHL) or single-sided deafness (SSD), may experience improved quality of life with the use of a cochlear implant (CI) in the affected ear. Quality of life assessment before and after implantation may reveal changes to aspects of hearing beyond those explicitly evaluated with behavioral measures. Methods: The present report completed 2 experiments investigating quality of life outcomes in CI recipients with UHL. The first experiment assessed quality of life during the 1st year of device use with 3 questionnaires: the Speech, Spatial, and Qualities of Hearing Scale (SSQ), the Abbreviated Profile of Hearing Aid Benefit (APHAB), and the Tinnitus Handicap Inventory. Twenty subjects were evaluated preoperatively and 1, 3, 6, 9, and 12 months post-activation. Quality of life results were compared over the study period using traditional scoring methods and the SSQ pragmatic subscales. Subscales specific to localization and speech perception in noise were compared to behavioral measures at the preoperative and 12-month intervals. The 2nd experiment evaluated quality of life preoperatively and at the 12-month interval for CI recipients with UHL and CI recipients with bilateral hearing loss, including conventional CI users and those listening with electric-acoustic stimulation (EAS). The 3 cohorts differed in CI candidacy criteria, including the amount of residual hearing in the contralateral ear. Results: For subjects with moderate-to-profound UHL, receipt of a CI significantly improved quality of life, with benefits noted as early as 1 month after initial activation. The UHL cohort reported less perceived difficulty at the pre- and postoperative intervals than the conventional CI and EAS cohorts, which may be due to the presence of the normal-hearing ear. Each group experienced a significant benefit in quality of life on the APHAB with CI use. Conclusions: Cochlear implantation in cases of substantial UHL may offer significant improvements in quality of life. Quality of life measures revealed a reduction in perceived tinnitus severity and subjective improvements in speech perception in noise, spatial hearing, and listening effort. While self-report of difficulties were lower for the UHL cohort than the conventional CI and EAS cohorts, subjects in all 3 groups reported an improvement in quality of life with CI use.

Factors Affecting Outcomes in Cochlear Implant Recipients Implanted With a Perimodiolar Electrode Array Located in Scala Tympani.

To identify primary biographic and audiologic factors contributing to cochlear implant (CI) performance variability in quiet and noise by controlling electrode array type and electrode position within the cochlea. Although CI outcomes have improved over time, considerable outcome variability still exists. Biographic, audiologic, and device-related factors have been shown to influence performance. Examining CI recipients with consistent array type and electrode position may allow focused investigation into outcome variability resulting from biographic and audiologic factors. Thirty-nine adults (40 ears) implanted for at least 6 months with a perimodiolar electrode array known (via computed tomography [CT] imaging) to be in scala tympani participated. Test materials, administered CI only, included monosyllabic words, sentences in quiet and noise, and spectral ripple discrimination. In quiet, scores were high with mean word and sentence scores of 76 and 87%, respectively; however, sentence scores decreased by an average of 35 percentage points when noise was added. A principal components (PC) analysis of biographic and audiologic factors found three distinct factors, PC1 Age, PC2 Duration, and PC3 Pre-op Hearing. PC1 Age was the only factor that correlated, albeit modestly, with speech recognition in quiet and noise. Spectral ripple discrimination strongly correlated with speech measures. For these recipients with consistent electrode position, PC1 Age was related to speech recognition performance. Consistent electrode position may have contributed to high speech understanding in quiet. Inter-subject variability in noise may have been influenced by auditory/cognitive processing, known to decline with age, and mechanisms that underlie spectral resolution ability.

Training to Improve Language Outcomes in Cochlear Implant Recipients

Cochlear implants (CI) have brought with them hearing ability for many prelingually deafened children. Advances in CI technology have brought not only hearing ability but speech perception to these same children. Concurrent with the development of speech perception has come spoken language development, and one goal now is that prelingually deafened CI recipient children will develop spoken language capabilities on par with those of normal hearing (NH) children. This goal has not been met purely on the basis of the technology, and many CI recipient children lag behind their NH peers with large variability in outcomes, requiring further behavioral intervention. It is likely that CI recipient children struggle to develop spoken language at NH-like levels because they have deficits in both auditory and cognitive skills that underlie the development of language. Fortunately, both the auditory and cognitive training literature indicate an improvement of auditory and cognitive functioning following training. It therefore stands to reason that if training improves the auditory and cognitive skills that support language learning, language development itself should also improve. In the present manuscript we will review the auditory and cognitive training and their potential impact on speech outcomes with an emphasis on the speech perception literature.