Cortical mechanisms of across-ear speech integration investigated using functional near-infrared spectroscopy (fNIRS).

This study aimed to investigate integration of alternating speech, a stimulus which classically produces a V-shaped speech intelligibility function with minimum at 2-6 Hz in typical-hearing (TH) listeners. We further studied how degraded speech impacts intelligibility across alternating rates (2, 4, 8, and 32 Hz) using vocoded speech, either in the right ear or bilaterally, to simulate single-sided deafness with a cochlear implant (SSD-CI) and bilateral CIs (BiCI), respectively. To assess potential cortical signatures of across-ear integration, we recorded activity in the bilateral auditory cortices (AC) and dorsolateral prefrontal cortices (DLPFC) during the task using functional near-infrared spectroscopy (fNIRS). For speech intelligibility, the V-shaped function was reproduced only in the BiCI condition; TH (with ceiling scores) and SSD-CI conditions had significantly higher scores across all alternating rates compared to the BiCI condition. For fNIRS, the AC and DLPFC exhibited significantly different activity across alternating rates in the TH condition, with altered activity patterns in both regions in the SSD-CI and BiCI conditions. Our results suggest that degraded speech inputs in one or both ears impact across-ear integration and that different listening strategies were employed for speech integration manifested as differences in cortical activity across conditions.

Combined-electrical optogenetic stimulation but not channelrhodopsin kinetics improves the fidelity of high rate stimulation in the auditory pathway in mice.

Novel stimulation methods are needed to overcome the limitations of contemporary cochlear implants. Optogenetics is a technique that confers light sensitivity to neurons via the genetic introduction of light-sensitive ion channels. By controlling neural activity with light, auditory neurons can be activated with higher spatial precision. Understanding the behaviour of opsins at high stimulation rates is an important step towards their translation. To elucidate this, we compared the temporal characteristics of auditory nerve and inferior colliculus responses to optogenetic, electrical, and combined optogenetic-electrical stimulation in virally transduced mice expressing one of two channelrhodopsins, ChR2-H134R or ChIEF, at stimulation rates up to 400 pulses per second (pps). At 100 pps, optogenetic responses in ChIEF mice demonstrated higher fidelity, less change in latency, and greater response stability compared to responses in ChR2-H134R mice, but not at higher rates. Combined stimulation improved the response characteristics in both cohorts at 400 pps, although there was no consistent facilitation of electrical responses. Despite these results, day-long stimulation (up to 13 h) led to severe and non-recoverable deterioration of the optogenetic responses. The results of this study have significant implications for the translation of optogenetic-only and combined stimulation techniques for hearing loss.

Performance After Cochlear Reimplantation Using a Different Manufacturer.

OBJECTIVE: To better understand cochlear implant (CI) performance after reimplantation with a different device manufacturer. STUDY DESIGN: Multisite retrospective review. SETTING: Tertiary referral centers. PATIENTS: Patients older than 4 years who received a CI and subsequently underwent CI reimplantation with a different manufacturer over a 20-year period. INTERVENTION: Reimplantation. MAIN OUTCOME MEASURE: The primary outcome was difference in the best CNC score obtained with the primary CI, compared with the most recent CNC score obtained after reimplantation. RESULTS: Twenty-nine patients met the criteria at three centers. The best average CNC score achieved by adult patients after primary cochlear implantation was 46.2% (n = 16), measured an average of 14 months (range: 3-36 mo) postoperatively. When looking at the most recent CNC score of adult patients before undergoing reimplantation, the average CNC score dropped to 19.2% (n = 17). After reimplantation, the average 3- to 6-month CNC score was 48.3% (n = 12), with most recent average CNC score being 44.4% (n = 17) measured an average of 19 months (range: 3-46 mo) postoperatively. There was no statistically significant difference (p = 0.321; t11 = 0.48) identified in performance between the best CNC score achieved by adult patients after primary cochlear implantation, and the most recent score achieved after reimplantation (n = 12). Analysis of prerevision and postrevision speech performance was not possible in pediatric patients (<18 yr old) because of differences in tests administered. CONCLUSION: Patients undergoing reimplantation with a different manufacturer achieved CNC score performance comparable to their best performance with their original device.

When to Start Computer-Based Auditory Training After Cochlear Implantation: Effects on Quality of Life and Speech Recognition.

OBJECTIVE: Computer-based auditory training (CBAT) has been shown to improve outcomes in adult cochlear implant (CI) users. This study evaluates in new CI users whether starting CBAT within 3 months of activation or later impacts CI outcomes. STUDY DESIGN: Prospective natural experiment. SETTING: Tertiary academic medical center. PATIENTS: Sixty-five new adult CI users. INTERVENTIONS: CBAT use over the first-year postactivation. MAIN OUTCOME MEASURES: Speech recognition scores and CIQOL-35 Profile score improvements between CI recipients who started CBAT resources early (<3 mo) and late (3-12 mo) postactivation. RESULTS: A total of 43 CI recipients started using CBAT within 3 months postactivation (early) and 22 after 3 months (late). Patients who used CBAT within 3 months postactivation showed significantly greater improvement in consonant-nucleus-consonant words (CNCw) (48.3 ± 24.2% vs 27.8 ± 24.9%; d = 0.84), AzBio Sentences in quiet (55.1 ± 28.0% vs 35.7 ± 36.5%; d = 0.62), and CIQOL-35 listening domain scores (18.2 ± 16.3 vs 6.9 ± 12.9, d = 0.73 [0.023, 1.43]), at 3 months postactivation, compared to those who had not yet initiated CBAT. However, by 12 months postactivation, after which all CI recipients had started CBAT, there were no differences observed between patients who started CBAT early or late in speech recognition scores (CNCw: d = 0.26 [-0.35, 0.88]; AzBio: d = 0.37 [-0.23, 0.97]) or in any CIQOL global or domain score (d-range = 0.014-0.47). CONCLUSIONS: Auditory training with self-directed computer software (CBAT) may yield speech recognition and quality-of-life benefits for new adult CI recipients. While early users showed greater improvement in outcomes at 3 months postactivation than users who started later, both groups achieved similar benefits by 12 months postactivation.

Investigating the Minimal Clinically Important Difference for AzBio and CNC Speech Recognition Scores.

OBJECTIVE: To assess the minimal clinically important difference (MCID) values for cochlear implant-related speech recognition scores, which have not been previously reported. STUDY DESIGN: Retrospective cohort. SETTING: Tertiary referral center. PATIENTS: Eight hundred sixty-three adult patients who underwent cochlear implantation between 2009 and 2022. MAIN OUTCOME MEASURES: MCID values for consonant-nucleus-consonant (CNC) word scores and AzBio sentences in quiet and noise scores using distribution-based methods (half-standard deviation, standard error of measurement, Cohen's d, and minimum detectable change). RESULTS: In this cohort, the mean preoperative CNC word score was 13.9% (SD, 15.6). The mean preoperative AzBio sentences in quiet score was 19.1% (SD, 22.1), and the mean preoperative AzBio sentences in noise score was 13.0% (SD, 12.0). The average MCID values of several distribution-based methods for CNC, AzBio in quiet, and AzBio in noise were 7.4%, 9.0%, and 4.9%, respectively. Anchor-based approaches with the Speech, Spatial, and Qualities of hearing patient-reported measure did not have strong classification accuracy across CNC or AzBio in quiet and noise scores (ROC areas under-the-curve ≤0.69), highlighting weak associations between improvements in speech recognition scores and subjective hearing-related abilities. CONCLUSIONS: Our estimation of MCID values for CNC and AzBio in quiet and noise allows for enhanced patient counseling and clinical interpretation of past, current, and future research studies assessing cochlear implant outcomes.

The impact of the Cochlear™ Osia® 2 System on patients with mixed or conductive hearing loss: A comparison with Cochlear™ Baha® Attract System outcomes.

OBJECTIVE: This prospective study assessed the efficacy of the Cochlear™ Osia® 2 System compared to the previous Baha® Attract System in patients with mixed or conductive hearing loss (MHL/CHL). METHODS: In this prospective case-control study, 10 patients (2 men and 8 women) with MHL/CHL were implanted with the Osia® 2 System. Their audiological outcomes were compared with 13 patients (2 men and 11 women) who had previously been implanted with the transcutaneous Baha® Attract system. We compared the complications and compliance of the two groups. Also, in the Osia 2 System group, subjective satisfaction was assessed using the Korean version of the International Outcome Inventory for Hearing Aids (K-IOI-HA) questionnaire and the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire. RESULTS: Complications such as poor magnetization, pain & infection, and abnormal noise were more common in the Baha Attract group, although not statistically significant. Also, the Osia 2 group exhibited better compliance. Subjective satisfaction was assessed using the K-IOI-HA and APHAB questionnaires with the Osia 2 group, revealing significantly improved scores in ease of communication, reverberation, background noise, and higher K-IOI-HA scores post-implantation. Postoperative-aided thresholds with both systems were significantly lower than preoperative-unaided thresholds, with the Osia 2 System demonstrating notably high satisfaction levels. Although both systems showed similar preoperative and postoperative word-recognition scores, the Osia 2 System provided greater audiological gain, especially at 2 kHz and 4 kHz frequencies. Additionally, the functional gain of both systems was comparable across all frequencies. CONCLUSIONS: The Osia 2 System demonstrated high subjective satisfaction and improved audiological outcomes compared to the Baha Attract system in patients with conductive or mixed hearing loss. Its superior audiological gain, particularly at critical frequencies, along with better compliance, suggests it as a favorable option for this patient population.

A real-world evaluation of the clinical benefits of improved sound processor technology among Chinese cochlear implant users: A focus on Cochlear Nucleus 7.

Real-world evidence is increasingly used to support clinical and regulatory decisions globally and may be a useful tool to study the unique needs of cochlear implant users in China. The ability to recognize and understand speech in noise is critical for cochlear implant users, however, this remains a challenge in everyday settings with fluctuating competing noise levels. The Cochlear™ Sound Processor, Nucleus® 7 (CP1000), includes Forward Focus, a spatial noise algorithm aimed to improve speech-in-noise performance, and Made for iPhone/iPod/iPad functionality. We conducted a prospective, single-center, open-label, within-participant, real-world evidence investigation in participants with cochlear implants. The primary objective of this study, conducted in China, was to compare speech perception in spatially separated dynamic noise with the Nucleus 7 to the recipients' current older Cochlear Sound Processor, including the Freedom and Nucleus 5 sound processors. A follow-up study monitored participants from the initial study up to 12-months post the fitting of their Nucleus 7 and investigated hearing ability, satisfaction, and usability of the device via a questionnaire. Forty participants were included in the initial study (age-range 3 to 49 years) and 29 continued to the follow-up study (age-range 5 to 28 years). The participants were heterogeneous in terms of age, cochlear implant experience, and duration of hearing loss. Nucleus 7 significantly improved participant speech recognition performance in noise by 7.54 dB when compared with the participants' current older sound processor (p<0.0001). Overall satisfaction with Nucleus 7 was 72%. Satisfaction in different hearing contexts ranged from 93.1% for understanding a 1:1 conversation in a quiet setting, 62.1% for understanding on the phone, to 34.5% hearing in complex noisy situations. The study demonstrated the benefits of the Nucleus 7 sound processor across different hearing environments in a Chinese population and showed improved hearing ability, usability, and satisfaction in a real-world every-day environment.

A cost-utility analysis of cochlear implants for single sided deafness in adults and children in the Netherlands.

BACKGROUND: Cochlear Implant (CI) has been shown to improve speech comprehension, sound localization and tinnitus in adults with Single-Sided-Deafness (SSD) compared to standard treatment currently available in the Dutch setting such as a CROS (Contralateral Routing of Signals) hearing device or a BCD (Bone Conduction Device). Also, for the pediatric population with SSD, CI has shown to be clinically meaningful. Because currently no information is available on the health economic effects of CI in adults and children with SSD in the Netherlands, a cost-utility analysis was conducted. METHODS: We developed a Markov cohort model, for both the adult and pediatric SSD population, with three states: implant, no implant, and dead. CI was compared with the Bone Conduction Device (BCD) treatment, requiring surgery and no specific treatment. The time horizon of the model was lifelong, costs were discounted with 3% and effects with 1.5%. A societal perspective was taken, including productivity costs in the analysis, with costing data based on publicly available prices for the Netherlands. Values for clinical outcome parameters, i.e. hearing gain, and event probabilities were based on existing literature. Deterministic and probabilistic sensitivity analyses as well as scenario analyses were performed to outline uncertainty of individual and combined parameters. RESULTS: Mean per patient costs for CI in the adult population were €194,051 (95%-CrI €177,274 to €211,108) compared to the total costs of €185,310 (95%-CrI €182,367 to €194,142) for BCD resulting in a cost difference of €8,826 (95%-CrI -€5,020 to €18,252). Compared to no treatment, the cost difference was -€25,089 (95%-CrI -€31,678 to -€6,003). Adults who were treated with CI gained 18.41 (95%-CrI 18.07 to 18.75) quality adjusted life years (QALY) whereas BCD patients gained 15.81 QALYs (95%-CrI 15.53 to 16.10), a difference of 2.60 QALYs (95%-CrI 2.15 to 3.05). The Incremental Cost Effectiveness Ratio (ICER) for adults with CI was determined to be €3,494/QALY gained. Patient without treatment gained 13.46 QALY (95%-CrI 13.20 to 13.73), a difference of 4.95 (95%-CrI 4.87 to 5.01) resulting in CI dominating no treatment. The ICER remained below the Dutch threshold of €20,000/QALY. The probabilistic sensitivity analyses confirmed the results. For children, CI dominated when compared to BCD and when compared to no treatment. Compared to BCD, CI led to a cost saving of €29,611 (95%-CrI -€126,800 to €54,375) and compared to no treatment, CI resulted in a cost saving of €57,658 (95%-CrI -€146,687 to €5,919). The incremental QALY gain compared to BCD was 7.22 (95%-CrI 4.19 to 8.55) and 26.03 (95%-CrI 20.82 to 31.06) compared to no treatment. CONCLUSIONS: Based on the results of this health economic evaluation with a Markov cohort model, it is very likely that CI is cost-effective compared to BCD and to no treatment in the Dutch adult and pediatric population with SSD. In both populations the ICER was below the Dutch cost-effectiveness threshold of €20,000/QALY.

[Early vocabulary development in Mandarin children with cochlear implantation].

Objective: To investigate the development of receptive and expressive vocabulary in Mandarin-speaking children with cochlear implants (CI) during the first year after CI activation. Methods: A total of 827 children (411 boys and 416 girls) who were implanted CI before 2.5 years of age from October 2019 to December 2022 in the Department of Auditory Implantation, Shandong Provincial ENT Hospital were included in this study. The Infant Checklist of the Mandarin Early Vocabulary Inventory (EVI) was used to assess the quantity and content of receptive and expressive vocabulary at the time of CI activation and at the 1st, 3rd, 6th, 9th, 12th months post-activation. SPSS 22.0 was used to describe the receptive and expressive vocabulary of CI children at the first year after activation. Results: During the first year after CI activation, CI children's receptive and expressive vocabulary consistently increased with the CI usage. The average number of receptive vocabulary and expressive vocabulary respectively increased from 0 to 178, and from 0 to 97. At the first year of post-activation, the number of receptive and expressive vocabulary of CI children were superior to that of hearing-age matched typical-hearing children, but fell behind of that of chronological age matched typical-hearing children. In terms of lexical categories, receptive and expressive vocabulary was acquired in the following order: nouns, verbs, adjectives, and pronouns. Among the top 50 words that CI children could express, nouns were the most common, then followed by verbs, adjectives, and pronouns. Father's education level can significantly and positively predictethe receptive vocabulary of CI children at the first year post-activation. At the first year after CI activation, the 10th, 25th, 50th, 75th, and 90th percentiles were 113, 149, 178, 202, 223 for the receptive vocabulary, and 9, 37, 97, 148, 188 for expressive vocabulary. Conclusion: For Mandarin speaking children with CI, the receptive and expression vocabulary continuely increased within the first year after CI activation. The ability to grasp receptive vocabulary precedes the ability to express expressive vocabulary. Compared to hearing-age matched typical-hearing children, CI children showed faster rate of the vocabulary growth, and earlier and more frequently verb expression. However, it still larged behind that of chronological age matched hearing normal children. CI children respectively understood and expressed nouns and verbs the first. In children with CI, the first concepts understood and expressed were nouns and verbs. Among the first 50 words expressed, nouns were the most numerous, and the age at which verbs were acquired was earlier than that for hearing-age matched typical-hearing children.

[Early auditory processing of speech in prelingually-deafened children with cochlear implants based on event-related potentials].

Objective: To investigate the early auditory discrimination of vowels, consonants and lexical tones in prelingually-deafened children with cochlear implants (CI) using auditory event-related potentials. Methods: Nineteen prelingually-deafened CI children and 19 normal hearing (NH) children were recruited in this study. A multi-deviant oddball paradigm was constructed using the monosyllable/ta1/as the standard stimulus and monosyllables/tu1/,/te1/, /da1/,/ra1/,/ta4/and/ta2/as the deviant stimuli. The event-related potentials evoked by vowel, consonant and lexical tone contrasts were recorded and analyzed in the two groups. Results: NH children showed robust mismatch negativities (MMNs) to vowel, consonant and lexical tone contrasts (P<0.05), whereas CI children only showed positive mismatch responses (pMMRs) and P3a responses to the vowel (P<0.05) and consonant contrasts (P<0.05) and no significant event-related potential to the lexical tone contrasts (P>0.05). The longer pMMR and P3a peak latencies (P<0.01) but similar amplitudes (P>0.05) were found in CI children than in NH children. CI children showed weaker phase synchronization of θ oscillations than NH children (P<0.05). The duration of CI use was positively correlated with the scores of Categories of Auditory Performance (CAP) (P=0.004), Speech Intelligibility Rate (SIR) (P=0.044) and Meaningful Auditory Integration Scale (MAIS) (P=0.001) in CI children. Conclusions: Prelingually-deafened CI children can process vowels and consonants at an early stage. However, their ability of processing speech, especially lexical tones, is still more immature compared with their NH peers. The event-related potentials could be objective electrophysiological indicators reflecting the maturity of CI children's auditory speech functions. Long-term CI use is beneficial for prelingually-deafened children to improve auditory and speech performance.

Cochlear Implantation in Post-Meningitis Deafness: Audiological, Imaging, and Postoperative Outcomes: A Systematic Review With Qualitative Synthesis.

INTRODUCTION: Post-meningitis deafness (PMD) is a potentially devastating cause of hearing loss among pediatric and adult patients, for which hearing rehabilitation with cochlear implants (CIs) remains the standard of care. To date, there have been limited systematic studies on the impact of cochlear ossification (CO) and time-to-implantation (TTI) on audiological outcomes. METHODS: An online database search was performed on the PubMed, Embase, and Scopus databases for articles within the past 20 years pertaining to audiological outcomes among pediatric and adult patients with PMD. Information on study characteristics, patient demographics, clinical outcomes, and postoperative complications was collected and analyzed. RESULTS: From 8,325 articles generated in the original search, 11 were included in the final analysis, representing 376 patients in total. Of the articles discussing TTI, the majority (3 of 4) found that a shorter TTI of 6 months on average led to improved audiological outcomes compared with control groups with a longer TTI. Of the articles that discussed the impact of preoperative CO, the majority (4 of 6) found that the presence of CO had a detrimental effect on postoperative audiological outcomes after CI. Finally, of the articles that discussed long-term audiological outcomes for PMD compared with the non-PMD control group after CI, the majority (4 of 7) found that PMD patients had inferior long-term outcomes. CONCLUSION: CI is a safe and effective treatment modality for PMD, with the majority of literature demonstrating improved long-term outcomes for patients without CO and a reduced TTI.

Evaluation of a Slim Modiolar Electrode Array: A Temporal Bone Study.

HYPOTHESIS: Evaluation of the Slim Modiolar (SM) electrode in temporal bones (TB) will elucidate the electrode's insertion outcomes. BACKGROUND: The SM electrode was designed for atraumatic insertion into the scala tympani, for ideal perimodiolar positioning and with a smaller caliber to minimize interference with cochlear biological processes. METHODS: The SM electrode was inserted into TBs via a cochleostomy. First, the axial force of insertion was measured. Next, TBs were inserted under fluoroscopy to study insertion dynamics, followed by histologic evaluation of electrode placement and cochlear trauma. A subset of TBs were inserted with the Contour Advance (CA) electrode for comparison. RESULTS: Sixteen of 22 insertions performed to measure the axial force of insertion had flat or near zero insertion force profiles. Six insertions had increased insertion forces, which were attributed to improper sheath depth before electrode insertion. Under real-time fluoroscopy, 23 of 25 TBs had uneventful insertion and good perimodiolar placement. There was 1 scala vestibuli insertion due to suboptimal cochleostomy position and 1 tip roll over related to premature electrode deployment. When compared with the CA electrode, 14 of 15 insertions with the SM electrode resulted in a more perimodiolar electrode position. No evidence of trauma was found in histologic evaluation of the 24 TBs with scala tympani insertions. CONCLUSION: TB evaluation revealed that the SM electrode exerts minimal insertion forces on cochlear structures, produces no histologic evidence of trauma, and reliably assumes the perimodiolar position. Nonstandard cochleostomy location, improper sheath insertion depth, or premature deployment of the electrode may lead to suboptimal outcomes.

Cochlear Implantation: Small Cochlear Diameter May Indicate Degree of Abnormality.

Cochlear size variation was first reported in 1884, and since then, there have been various reports confirming the same. Yet, there is no single report that has displayed the wide variations in the cochlear size in a single layout capturing the cochlea in the oblique coronal view/ cochlear view. Basal turn diameter (A-value) was measured in the oblique coronal plane using the OTOPLAN® otological preplanning tool in 104 computed tomography (CT) scans of the temporal bones of cochlear implant (CI) recipients in a tertiary CI center. All CT scans with an image resolution of at least 0.5 mm and identified as having cochleae with normal anatomy were included in this study. A 3-dimensional (3D) segmentation was performed using the 3D slicer and visualized to evaluate the impact of cochlear size on the number of turns studied. The A-value was found to vary between 7.3 mm and 10.4 mm among the studied patients. Three-dimensional segmentation of the inner ear revealed only 2 turns of the cochlea in 4 ears, with A-values of 7.3, 8.8, 7.8, and 7.7 mm. One ear had only 11 /2 turns of the cochlea, with an A-value of 7.9 mm. As a further advancement in the assessment of cochlear size as determined by the A-value, 3D segmentation of the complete inner ear provides a full picture of the number of cochlear turns. Three-dimensional segmentation of the entire inner ear could help improve the preoperative planning of CI surgery and have implications for electrode array selection. Cochlear size could be a predictor of the number of cochlear turns, even in cases that look normal from the radiological findings. The findings of this study could help in improving the preoperative planning for a more successful CI surgery by differentiating between the normal and abnormal cochlea.