Cochlear Implant

Patients' satisfaction and efficacy of modern conventional hearing aids: A comprehensive analysis of the self-reported user experiences in adult people

OBJECTIVE

Hearing loss is a widespread condition that impacts the quality of life, affecting communication, social interactions, and cognitive functions. This study aimed to evaluate the subjective benefit and satisfaction of using hearing aids among patients since the adoption rate of hearing aids remains low.

METHODS

The study retrospectively analysed data from 133 patients with hearing aids, using the Abbreviated Profile of Hearing Aid Benefit (APHAB) and the Satisfaction with Amplification in Daily Life (SADL) questionnaires. Patients were divided into two groups based on this median age and sex for comparative analysis. The Mann Whitney test was applied with references to numerical parameters (APHAB and SADL) to assess differences between male vs female subjects and adults vs elderly. The Spearman correlation test was applied to assess the possible correlation between APHAB and SADL. A p-value lower than 0.05 was considered statistically significant.

RESULTS

Results indicated no significant gender differences in most APHAB and SADL subscales, except for the SADL "personal image" subscale, which showed lower scores for women (p =  0.023). Age-based comparison revealed no significant differences in APHAB scores; the SADL scores showed significant differences in the "positive effect" (p = 0.013), "negative features" (p = 0.005), and overall scores (p = 0.039), with lower satisfaction in older patients. Correlation analysis identified a positive relationship between the SADL "negative features" and APHAB "aversiveness" subscales (p = 0.042, correlation coefficient ρ = 0.176).

CONCLUSIONS

The study highlights the importance of addressing subjective perceptions and aesthetic concerns in hearing aid adoption, emphasizing the need for personalized rehabilitation strategies to improve patient outcomes and satisfaction.

LEVEL OF EVIDENCE

Level 3.

Study on Recovery Strategy of Hearing Loss & SGN Regeneration Under Physical Regulation

The World Health Organization (WHO) reports that by 2050, nearly 2.5 billion people are expected to have some degree of hearing loss (HL) and at least 700 million will need hearing rehabilitation. Therefore, there is an urgent need to develop treatment strategies for HL. At present, the main treatment strategies for HL are hearing aids and cochlear implants (CIs), which cannot achieve a radical cure for HL. Relevant studies have shown that the most fundamental treatment strategy for sensorineural hearing loss (SNHL) is to regenerate hair cells and spiral ganglion neurons (SGNs) through stem cells to repair the structure and function of cochlea. In addition, physical stimulation strategies, such as electricity, light, and magnetism have also been used to promote SGN regeneration. This review systematically introduces the classification, principle and latest progress of the existing hearing treatment strategies and summarizes the advantages and disadvantages of each strategy. The research progress of physical regulation mechanism is discussed in detail. Finally, the problems in HL repair strategies are summarized and the future development direction is prospected, which could provide new ideas and technologies for the optimization of hearing treatment strategies and the research of SGN repair and regeneration through physical regulation.

Transimpedance Matrix Measurement (TIM) Parameters Evaluation for the Assessment of Cochlear Implant Electrode Placement and Modiolar Proximity in Children

Introduction: Transimpedance matrix measurement (TIM) is an electrophysiological measurement protocol of the impedance patterns of electrode contacts within the cochlea. Several studies have reported that TIM is an effective tool for the identification of abnormal electrode array placement. However, the normative values for properly inserted electrodes, as well as correlation of the TIM patterns with the electrode position, are not completely determined. Objectives: The first aim of this study is to establish normative values of TIM measurements obtained in children with proper electrode array insertion and tip fold-over, with proper inner ear anatomy and in congenital anomalies. The second aim of this study is to compare TIM measurements in Slim Modiolar (SM) and in Contour Advance (CA) electrodes, as their position is different according to the modiolus proximity. Methods: A total of 55 pediatric patients were included in the study and underwent cochlear implantation. 62 intraoperative measurements were conducted in this group-50 in children with normal inner ear anatomy and 12 in children with inner ear malformations. After each implantation, a plain x-ray was obtained. Results: There were clear statistically significant differences in TIM patterns in patients where electrode fold-over was confirmed and between SM and CA electrodes. Conclusions: TIM is a promising technique for intraoperative analysis of electrode placement. TIM patterns differ and correlate consistently with the different models of array implanted. This study is the first to report TIM patterns observed in children with normal inner ear anatomy and in inner ear malformations.

Unilateral Versus Bilateral Cochlear Implants in Adults: A Cross-Sectional Questionnaire Study Across Multiple Hearing Domains

AIM

The aim of this study was to assess the subjective experiences of adults with different cochlear implant (CI) configurations-unilateral cochlear implant (UCI), bilateral cochlear implant (BCI), and bimodal stimulation (BM)-focusing on their perception of speech in quiet and noisy environments, music, environmental sounds, people's voices and tinnitus.

METHODS

A cross-sectional survey of 130 adults who had undergone UCI, BCI, or BM was conducted. Participants completed a six-item online questionnaire, assessing difficulty levels and psychological impact across auditory domains, with responses measured on a 10-point scale. Statistical analyses were performed to compare the subjective experiences of the three groups.

RESULTS

Patients reported that understanding speech in noise and tinnitus perception were their main concerns. BCI users experienced fewer difficulties with understanding speech in both quiet (p < 0.001) and noisy (p = 0.008) environments and with perceiving non-vocal sounds (p = 0.038) compared to UCI and BM users; no significant differences were found for music perception (p = 0.099), tinnitus perception (p = 0.397), or voice naturalness (p = 0.157). BCI users also reported less annoyance in quiet (p = 0.004) and noisy (p = 0.047) environments, and in the perception of voices (p = 0.009) and non-vocal sounds (p = 0.019). Tinnitus-related psychological impact showed no significant differences between groups (p = 0.090).

CONCLUSIONS

Although speech perception in noise and tinnitus remain major problems for CI users, the results of our study suggest that bilateral cochlear implantation offers significant subjective advantages over unilateral implantation and bimodal stimulation in adults, particularly in difficult listening environments.

Pupillometry and perceived listening effort for cochlear implant users-a comparison of three speech-in-noise tests

OBJECTIVE

Measuring listening effort using pupillometry is challenging in cochlear implant (CI) users. We assess three validated speech tests (Matrix, LIST, and DIN) to identify the optimal speech material for measuring peak-pupil-dilation (PPD) in CI users as a function of signal-to-noise ratio (SNR).

DESIGN

Speech tests were administered in quiet and two noisy conditions, namely at the speech recognition threshold (0 dB re SRT), i.e. the SNR where speech intelligibility (SI) was 50%, and at a more favourable SNR of +6 dB re SRT. PPDs and subjective ratings of effort were obtained.

STUDY SAMPLE

Eighteen unilaterally implanted CI users.

RESULTS

LIST sentences revealed significantly different PPDs between +6 and 0 dB re SRT and DIN triplets between quiet and +6 dB re SRT. PPDs obtained with the Matrix test were independent of SNR and yielded large PPDs and high subjective ratings even in quiet.

CONCLUSIONS

PPD is a sensitive measure for listening effort when processing LIST sentences near 0 dB re SRT and when processing DIN triplets at more favourable listening conditions around +6 dB re SRT. PPDs obtained with the Matrix test were insensitive to SNR, likely because it is demanding for CI users even in quiet.

Determinants of Success in Revision Cochlear Implant Surgeries: A Comprehensive Evaluation of Patient, Surgical, and Radiological Factors

Background/Objectives: This study aims to evaluate factors influencing revision cochlear implant surgeries, including patient demographics, surgical techniques, and radiological findings. The main aim was to identify factors influencing surgical success to inform clinical treatment and enhance patient outcomes. Methods: This cross-sectional study included adult patients over the age of 18 who underwent revision cochlear implant surgery due to implant-related complications. Data were collected from systematic chart reviews of electronic medical records, including demographics, surgical techniques, radiological output from standard high-resolution CT and MRI, and intraoperative data. The primary outcome was surgical success, defined by improved auditory function, stable device positioning, and absence of postoperative complications. Statistical analyses, including multivariate logistic regression, were conducted to identify independent predictors of surgical success. Results: A total of 188 patients were included, with a mean age of 45.67 years. Younger age, shorter duration of implant use, modified surgical techniques, and absence of co-morbidities are key factors contributing to surgical success. Modified surgical techniques were associated with better outcomes (39.29% vs. 68.75%, OR: 2.78, 95% CI: 1.25-6.14, p = 0.012). Radiological patterns significantly affected outcomes, with normal findings associated with higher success rates. In contrast, abnormalities such as electrode migration (OR: 2.14, 95% CI: 1.12-4.09, p = 0.021) and ossification (r = -0.51, β = -0.44, adjusted R2 = 0.25, p < 0.01) were correlated with poorer results. Smoking status, when comparing smokers to non-smokers, was associated with unfavorable outcomes (20.00% vs. 45.83%, OR: 2.01, 95% CI: 1.01-4.01, p = 0.048), and a history of previous surgeries (21.43% vs. 37.50%, OR: 1.95, 95% CI: 1.03-3.71, p = 0.033) was significantly associated with unfavorable outcomes. Conclusions: Statistically, significantly better outcomes are positively correlated with the duration of the first cochlear implant experience and negatively with prior otologic pathology and nonauditory environmental influences on surgical success. Younger age, modified surgical techniques, and normal radiological findings were related to better outcomes; complications such as electrode migration and ectopic ossification were strong predictive factors for surgical failure. These findings underscore the need for tailored surgical approaches and early intervention to enhance outcomes in revision cochlear implant surgeries.

fNIRS Changes in the Middle Temporal and Occipital Cortices After a Cochlear Implant

OBJECTIVES

The relationship between the middle temporal (MTG) and occipital cortices in post-lingually deaf (PLD) individuals is unclear. This study aimed to investigate changes in the MTG and occipital cortices excitability and their effects on the occipital cortex in individuals with PLD after receiving a cochlear implant (CI).

METHODS

Twenty-six individuals with severe-to-profound binaural sensorineural PLD were assessed clinically. Nine individuals had received a unilateral cochlear implant over 6 months, while 17 had not. Brodmann area 19 (BA19, extra-striate occipital cortex) and MTG (auditory-related area of cortex) were selected as regions of interest. The excitability of the ROI was observed and compared in the surgery and no-surgery groups by functional near-infrared spectroscopy (fNIRS) in the resting state, and correlations between connectivity of the MTG and occipital cortex, and as well as the duration of time that had elapsed following CI surgery, were investigated.

RESULTS

fNIRS revealed enhanced global cortical connectivity in the BA19 and MTG on the operative side (p < 0.05) and the connectivity between BA19 and the MTG also increased (p < 0.05). The connectivity between the MTG and BA19 was positively correlated with the duration of cochlear implantation, as was the case for BA18.

CONCLUSION

There was evidence for remodeling of the cerebral cortex: increased excitability was observed in the MTG and BA19, and their connectivity was enhanced, indicating a synergistic effect. Moreover, the MTG may further stimulate the visual cortex by strengthening their connectivity after CI.

LEVEL OF EVIDENCE

3 Laryngoscope, 135:331-338, 2025.

Effect of Cochlear Implantation on Air Conduction and Bone Conduction Elicited Vestibular Evoked Myogenic Potentials-A Scoping Review

Background/Objectives: Cochlear implantation (CI) is an effective intervention for individuals with severe to profound hearing loss; however, it may impact vestibular function due to its proximity to related anatomical structures. Vestibular evoked myogenic potentials (VEMPs) assess the function of the saccule and utricle, critical components of the vestibular system. This review examines CI's impact on air conduction (AC) and bone conduction (BC) VEMP responses. Methods: A scoping review was conducted following PRISMA guidelines, using databases such as Medline, Embase, Cochrane Library, Scopus, and ProQuest Dissertations. Studies reporting on AC and/or BC-VEMP in CI recipients were included. Data extraction focused on VEMP response rates, amplitudes, and latencies pre- and post-CI. Risk of bias/quality assessment was performed using the Newcastle-Ottawa Scale. Results: Out of 961 studies identified, 4 met the inclusion criteria, encompassing a total of 245 CI-implanted ears. Results indicated that AC-VEMP responses were often reduced or absent post-CI, reflecting the influence of surgical changes in the middle ear mechanics rather than otolith dysfunction. In contrast, BC-VEMP responses were more consistently preserved, suggesting that BC stimuli bypass the middle ear and more accurately delineate otolith function. Variations in VEMP outcomes were noted depending on the surgical approach and individual patient factors. Conclusions: CI impacts vestibular function as measured by VEMP, with AC-VEMP showing greater susceptibility to postoperative changes compared to BC-VEMP. The presence of preserved BC-VEMP alongside absent AC-VEMP underscores the need to differentiate between these measures in assessing vestibular function.

Investigating the effect of cochlear implant usage metrics on cortical auditory-evoked potential responses in adult recipients post-implantation

Introduction

This study examines the effect of cochlear implant (CI) device usage metrics on post-operative outcomes in unilateral CI recipients. The primary objective is to investigate the relationship between CI usage frequency (average daily CI use) and duration (total years of CI use) on electrically evoked cortical auditory-evoked potential (eCAEP) response peak latency (ms) and amplitude (μV).

Methods

Adult CI users (n = 41) who previously exhibited absent acoustically evoked CAEP responses participated in the study. The peak latency and amplitude of eCAEP P1-N1-P2 responses were recorded, when present for the apical, medial, and basal test electrode contacts. CI duration was defined as the number of years between the date of CI activation and date that eCAEP testing was performed. CI usage frequency was defined as the average number of hours per day of audio processor use, which was recorded using the CI programming software.

Results

Overall, 27 participants (65.85%) exhibited detectable eCAEP responses across one or more electrode contacts. Among these, 18 participants (43.9%) elicited eCAEP responses at all three electrode contacts, while 7 (17.07%) showed responses at two contacts, and 2 (4.88%) at one contact. For the remaining 14 participants (34.15%), eCAEP responses were either absent or undetectable. CI usage frequency (average daily CI use [hours/day]) was captured for 32 (78%) of the participants (median 10.35 h/day, range 0.2-16 h/day). Participants with present eCAEP responses for the basal electrode (n = 14) showed significantly higher CI usage frequency (11.8 h/day, p = 0.026) compared to those with non-detectable responses (6.25 h/day). An association was found between higher CI usage frequency and reduced N1 (p = 0.002), P2 (p = 0.0037) and P1-N1 inter-peak (p = 0.015) response latency (ms). While CI duration (total CI use [years]) did not differ significantly between groups based on the presence of eCAEP responses, an association was found between greater CI duration and increased eCAEP response amplitude (μV) for the P2 (p = 0.008) and N1-P2 peak-peak (p = 0.009) response components.

Discussion

Additionally, most (65.85%) participants who previously exhibited absent acoustic CAEP responses developed eCAEP responses after consistent CI use and increased CI experience. These findings may suggest a potential for cortical plasticity and adaptation with consistent CI use over time. Recognizing the impact of device usage metrics on neural responses post-implantation enhances our understanding of the importance of consistent daily CI use. Overall, these findings contribute to addressing the variability among CI users, improving post-operative outcomes and advancing the standard of personalized care in auditory rehabilitation.

The association of intraoperative electric field and neural excitation patterns of the cochlear implant with patient-related factors of age, gender, cochlear diameter, and postoperative speech measures

PURPOSE

To assess the relationships between the electric field (EF) and neural excitation patterns in cochlear implants (CIs) and explore their associations with the cochlear diameter, patient age and gender, and postoperative speech recognition.

METHOD

The intraoperative transimpedance matrix (TIM) and spread of excitation (SOE) measures were computed to obtain their 50 % widths corresponding to six electrode contacts of a lateral-wall electrode array. The measures were then analyzed for intercorrelations, associations with the cochlear diameter, as well as age and gender-related differences. The relationships between the computed intraoperative measures and postimplant speech recognition were also studied.

RESULTS

The TIM and SOE 50 % widths present moderate correlations and exhibit differences between adults and children. The TIM 50 % widths show additional associations with the cochlear diameter and partly vary with the implantee's gender. Speech recognition was found to have a significant relationship with the exponential spread coefficients (ESCs) obtained for individual electrode contacts.

CONCLUSION

Although interrelated, the EF and neural excitation measures of the CI are associated with different variables. The ESC, derived from computations of the TIM, is the only measure linked to postoperative speech recognition.

Listening Effort Measured With Pupillometry in Cochlear Implant Users Depends on Sound Level, But Not on the Signal to Noise Ratio When Using the Matrix Test

OBJECTIVES

We investigated whether listening effort is dependent on task difficulty for cochlear implant (CI) users when using the Matrix speech-in-noise test. To this end, we measured peak pupil dilation (PPD) at a wide range of signal to noise ratios (SNR) by systematically changing the noise level at a constant speech level, and vice versa.

DESIGN

A group of mostly elderly CI users performed the Dutch/Flemish Matrix test in quiet and in multitalker babble at different SNRs. SNRs were set relative to the speech-recognition threshold (SRT), namely at SRT, and 5 and 10 dB above SRT (0 dB, +5 dB, and +10 dB re SRT). The latter 2 conditions were obtained by either varying speech level (at a fixed noise level of 60 dBA) or by varying noise level (with a fixed speech level). We compared these PPDs with those of a group of typical hearing (TH) listeners. In addition, listening effort was assessed with subjective ratings on a Likert scale.

RESULTS

PPD for the CI group did not significantly depend on SNR, whereas SNR significantly affected PPDs for TH listeners. Subjective effort ratings depended significantly on SNR for both groups. For CI users, PPDs were significantly larger, and effort was rated higher when speech was varied, and noise was fixed for CI users. By contrast, for TH listeners effort ratings were significantly higher and performance scores lower when noise was varied, and speech was fixed.

CONCLUSIONS

The lack of a significant effect of varying SNR on PPD suggests that the Matrix test may not be a feasible speech test for measuring listening effort with pupillometric measures for CI users. A rating test appeared more promising in this population, corroborating earlier reports that subjective measures may reflect different dimensions of listening effort than pupil dilation. Establishing the SNR by varying speech or noise level can have subtle, but significant effects on measures of listening effort, and these effects can differ between TH listeners and CI users.

Electrophysiological Characteristics in Pediatric Cochlear Implantation

AIMS

Cochlear implantation is a potential intervention for individuals with severe to profound hearing loss, in particular in the pediatric population. This literature review aims to comprehensively evaluate the applications of electrophysiological tests in enhancing cochlear implant (CI) outcomes for children.

METHODS

A literature review searched Medline and PubMed databases for articles on electrophysiological tests in CI children, using the terms "electrophysiological tests," "children," and "cochlear implant." The systematic search leads to 72 eligible texts.

RESULTS

Electrophysiological tests can be used to test CI children without the need for their active participation. These tests can be helpful in identifying and improving the health of deaf children in various ways, such as determining the CI functional status, the semantic integration effects in CI children, the effect of central auditory structures in speech stimulus processing, the development of lexical-semantic in CI children, and tracking the maturation of the central auditory system. CI enhances central auditory nervous system (CANS) maturation and auditory/language skills.

CONCLUSION

The quality of electrophysiological tests can be improved to enhance hearing outcome prediction, postoperative physiology understanding, and hearing loss mechanisms. Electrophysiological tests study CANS maturation, identify lesions, aid CI programming, determine prognosis, and treatment outcomes.

Examining the Quality of Life of Hearing-Impaired Children in Nepal with Cochlear Implants: Perspectives From Parents

Millions of people worldwide suffer from hearing loss, a common sensory condition. However, new developments in cochlear implants have drastically transformed children's lives. However, there is still much to learn about the complex effects of cochlear implant interventions on children's lives and the unique difficulties experienced by Nepalese families. This study aims to comprehensively evaluate parents' perspectives regarding the quality of life of children with cochlear implants in Nepal. This study utilized the 'Children with Cochlear Implants: Parental Perspectives' (CCIPP) questionnaire, focusing on parents' viewpoints to assess the quality of life of Nepalese children with cochlear implants. A purposive sampling approach encompassed 22 families who completed the questionnaire. The study showed good parental ratings; the mean overall quality of life score was more than three (out of five), indicating significant gains following cochlear implantation. The greatest scores were for communication abilities, but issues with the implantation procedure and educational components persisted. A strong relationship existed between communication and several quality-of-life dimensions, highlighting communication's critical role in improving social interactions, well-being, and self-reliance. From the viewpoint of the parents of Nepalese children with cochlear implants, the current research represents a significant change in our knowledge of their quality of life. Even though there have been significant gains, targeted interventions are necessary to address post-implantation problems and educational challenges. The study recommends customized support networks and academic achievements to help Nepal's children with cochlear implant treatments.

Knowledge and Practice in Cochlear Re-Implantation in the UK: A Survey for Audiologists

BACKGROUND

Cochlear implantation (CI) has proven to be a highly effective method for rehabilitating individuals with severe to profound hearing loss. However, challenges persist, particularly in cases where CI failure necessitates re-implantation. This study aims to address the gap in understanding the knowledge and practices of audiologists in the UK regarding cochlear re-implantation through a comprehensive questionnaire survey.

METHODS

A bespoke questionnaire was distributed to audiologists working with CI across the UK. The survey, which included multiple-choice items, open-text responses, and visual analogue scales, was made accessible via an online link shared through professional bodies, email groups, and social media platforms.

RESULTS

The survey received 27 responses, predominantly from female audiologists (71.4%), with significant representation from London (28.6%) and the East of England (21.4%). A majority of respondents had over 16 years of CI experience (35.7%) and held a master's degree (60.7%). Key reasons for CI re-implantation included electrode failure (82.1%) and hermetic seal failure (60.7%). While respondents showed strong confidence in counselling (88.8%) and managing re-implanted devices (84.6%), there was a noted variation in opinions regarding the need for additional training in intraoperative measures.

CONCLUSION

This survey highlights the current practices and training needs of UK audiologists in CI re-implantation. This underscores the importance of targeted training to fill knowledge gaps and improve clinical care during CI re-implantation, ultimately enhancing outcomes for both audiologists and CI recipients.

Comparison of depth of electrode insertion between cochleostomy and round window approach: a cadaveric study

INTRODUCTION

Round window approach and cochleostomy approach can have different depth of electrode insertion during cochlear implantation which itself can alter the audiological outcomes in cochlear implant.

OBJECTIVE

The current study was conducted to determine the difference in the depth of electrode insertion via cochleostomy and round widow approach when done serially in same temporal bone.

METHODOLOGY

This is a cross-sectional study conducted in the Department of Otorhinolaryngology in conjunction with Department of Anatomy and Department of Diagnostic and Interventional Radiology over a period of 1 year. 12-electrode array insertion was performed via either approach (cochleostomy or round window) in the cadaveric temporal bone. HRCT temporal bone scan of the implanted temporal bone was done and depth of insertion and various cochlear parameters were calculated.

RESULT

A total of 12 temporal bones were included for imaging analysis. The mean cochlear duct length was 32.892 mm; the alpha and beta angles were 58.175° and 8.350°, respectively. The mean angular depth of electrode insertion via round window was found to be 325.2° (SD = 150.5842) and via cochleostomy 327.350 (SD = 112.79) degree and the mean linear depth of electrode insertion via round window was found to be 18.80 (SD = 4.4962) mm via cochleostomy 19.650 (SD = 3.8087) mm, which was calculated using OTOPLAN 1.5.0 software. There was a statically significant difference in linear depth of insertion between round window and cochleostomy. Although the angular depth of insertion was higher in CS group, there was no statistically significant difference with round window type of insertion.

CONCLUSION

The depth of electrode insertion is one of the parameters that influences the hearing outcome. Linear depth of electrode insertion was found to be more in case of cochleostomy compared to round window approach (p = 0.075) and difference in case of angular depth of electrode insertion existed but not significant (p = 0.529).

An overview of risk factors, management and prevention of cochlear implant infections

PURPOSE OF REVIEW

With cochlear implantation becoming increasingly performed worldwide, an understanding of the risk factors, preventive measures, and management of cochlear implant (CI) infection remains important given the significant morbidity and cost it conveys.

RECENT FINDINGS

At the turn of the 21st century there was a decrease in rates of CI infection, particularly meningitis, following the discontinuation of positioner use for CI. However, in more recent years rates of CI infection have remained largely static. Recently, studies evaluating preventive measures such as pneumococcal vaccination, S. aureus decolonization and surgical antibiotic prophylaxis have emerged in the literature.

SUMMARY

Prompt recognition of CI infection and appropriate investigation and management are key, however at present treatment is largely informed by cohort and case-control studies and expert opinion. Preventive measures including pneumococcal vaccination, S. aureus decolonization and preoperative antibiotic prophylaxis play a role in reducing rates of CI infection. However, there remains a need for well designed clinical trials to provide higher level evidence to better guide preventive measures for, and management decisions of, CI infections in the future.

Advances in 3D Inner Ear Reconstruction Software for Cochlear Implants: A Comprehensive Review

Auditory impairment stands as a pervasive global issue, exerting significant effects on individuals' daily functioning and interpersonal engagements. Cochlear implants (CIs) have risen as a cutting-edge solution for severe to profound hearing loss, directly stimulating the auditory nerve with electrical signals. The success of CI procedures hinges on precise pre-operative planning and post-operative evaluation, highlighting the significance of advanced three-dimensional (3D) inner ear reconstruction software. Accurate pre-operative imaging is vital for identifying anatomical landmarks and assessing cochlear deformities. Tools like 3D Slicer, Amira and OTOPLAN provide detailed depictions of cochlear anatomy, aiding surgeons in simulating implantation scenarios and refining surgical approaches. Post-operative scans play a crucial role in detecting complications and ensuring CI longevity. Despite technological advancements, challenges such as standardization and optimization persist. This review explores the role of 3D inner ear reconstruction software in patient selection, surgical planning, and post-operative assessment, tracing its evolution and emphasizing features like image segmentation and virtual simulation. It addresses software limitations and proposes solutions, advocating for their integration into clinical practice. Ultimately, this review underscores the impact of 3D inner ear reconstruction software on cochlear implantation, connecting innovation with precision medicine.

Evaluating Listening Effort in Unilateral, Bimodal, and Bilateral Cochlear Implant Users

OBJECTIVE

Evaluate listening effort (LE) in unilateral, bilateral, and bimodal cochlear implant (CI) users. Establish an easy-to-implement task of LE that could be useful for clinical decision making.

STUDY DESIGN

Prospective cohort study.

SETTING

Tertiary neurotology center.

METHODS

The Sentence Final Word Identification and Recall Task, an established measure of LE, was modified to include challenging listening conditions (multitalker babble, gender, and emotional variation; test), in addition to single-talker sentences (control). Participants listened to lists of sentences in each condition and recalled the last word of each sentence. LE was quantified by percentage of words correctly recalled and was compared across conditions, across CI groups, and within subjects (best aided vs monaural).

RESULTS

A total of 24 adults between the ages of 37 and 82 years enrolled, including 4 unilateral CI users (CI), 10 bilateral CI users (CICI), and 10 bimodal CI users (CIHA). Task condition impacted LE (P < .001), but hearing configuration and listener group did not (P = .90). Working memory capacity and contralateral hearing contributed to individual performance.

CONCLUSION

This study adds to the growing body of literature on LE in challenging listening conditions for CI users and demonstrates feasibility of a simple behavioral task that could be implemented clinically to assess LE. This study also highlights the potential benefits of bimodal hearing and individual hearing and cognitive factors in understanding individual differences in performance, which will be evaluated through further research.

A 10-year in-depth follow-up of post-lingual hearing loss patients with Chinese domestic cochlear implants

BACKGROUND

Follow-up of cochlear implant effectiveness is mainly focused on 3 years postoperatively, and studies with more than 5 years of observation are rare, especially for local Chinese brands.

OBJECTIVES

Nurotron (Chinese domestic cochlear implant brand) CI recipients who participated in the clinical trial in 2009 were followed-up for 10 years prospectively, providing data to guide doctors and patients.

MATERIAL AND METHODS

From December 2009 to April 2010, 57 subjects underwent Nurotron Venus CI surgery at multiple-centers, and were continued to be followed up and assessed at 1, 2, 3, 4, 5, and 10 years after switch on.

RESULTS

All recipients were successfully implanted with CIs with no difficulty in subsequent use with one reported case of re-implantation at 9 years after implantation. The aided hearing thresholds were significantly improved at one month after switch on (p < 0.0001) and remained stable afterwards for 10 years. Speech recognition scores were significantly higher than pre-operative results (p < 0.05) and continued to improve till 3 years after switch on. At 10 years post-operation, most subjects had improved QOL scores in most sub-items.

CONCLUSIONS AND SIGNIFICANCE

Nurotron Venus CI System provides long-term, stable results in hearing speech assistance capabilities and can improve the quality of life of CI recipients.

Development of a feline model for preclinical research of a new translabyrinthine auditory nerve implant

Cochlear implants are among the most successful neural prosthetic devices to date but exhibit poor frequency selectivity and the inability to consistently activate apical (low frequency) spiral ganglion neurons. These issues can limit hearing performance in many cochlear implant patients, especially for understanding speech in noisy environments and in perceiving or appreciating more complex inputs such as music and multiple talkers. For cochlear implants, electrical current must pass through the bony wall of the cochlea, leading to widespread activation of auditory nerve fibers. Cochlear implants also cannot be implanted in some individuals with an obstruction or severe malformations of the cochlea. Alternatively, intraneural stimulation delivered via an auditory nerve implant could provide direct contact with neural fibers and thus reduce unwanted current spread. More confined current during stimulation can increase selectivity of frequency fiber activation. Furthermore, devices such as the Utah Slanted Electrode Array can provide access to the full cross section of the auditory nerve, including low frequency fibers that are difficult to reach using a cochlear implant. However, further scientific and preclinical research of these Utah Slanted Electrode Array devices is limited by the lack of a chronic large animal model for the auditory nerve implant, especially one that leverages an appropriate surgical approach relevant for human translation. This paper presents a newly developed transbullar translabyrinthine surgical approach for implanting the auditory nerve implant into the cat auditory nerve. In our first of a series of studies, we demonstrate a surgical approach in non-recovery experiments that enables implantation of the auditory nerve implant into the auditory nerve, without damaging the device and enabling effective activation of the auditory nerve fibers, as measured by electrode impedances and electrically evoked auditory brainstem responses. These positive results motivate performing future chronic cat studies to assess the long-term stability and function of these auditory nerve implant devices, as well as development of novel stimulation strategies that can be translated to human patients.

Cochlear implant positioning: development and validation of an automatic method using computed tomography image analysis

The aim of this study was to preoperatively asses the feasibility of drilling a bony recess for the fixation of a cochlear implant in the temporal bone. Even though complications are rare with cochlear implantations, drilling at the site of implantation have resulted in hematoma or cerebrospinal fluid leakage. Mainly in cases with a reduced temporal bone thickness, the risk for complications has increased, such as in paediatric patients.

Methods

An in-house designed semi-automatic algorithm was developed to analyse a 3D model of the skull. The feasibility of drilling the recess was determined by a gradient descent method to search for the thickest part of the temporal bone. Feasibility was determined by the residual bone thickness which was calculated after a simulated drilling of the recess at the thickest position. An initial validation of the algorithm was performed by measuring the accuracy of the algorithm on five 3D models with known thickest locations for the recess. The accuracy was determined by a part comparison between the known position and algorithm provided position.

Results

In four of the five validation models a standard deviation for accuracy below the predetermined cut-off value of 4.2 mm was achieved between the actual thickest position and the position determined by the algorithm. Furthermore, the residual thickness calculated by the algorithm showed a high agreement (max. 0.02 mm difference) with the actual thickness.

Conclusion

With the developed algorithm, a semi-automatic method was created to analyse the temporal bone thickness within a specified region of interest on the skull. Thereby, providing indications for surgical feasibility, potential risks for anatomical structures and impact on procedure time of cochlear implantation. This method could be a valuable research tool to objectively assess feasibility of drilling a recess in patients with thin temporal bones preoperatively.

Current advances in biomaterials for inner ear cell regeneration

Inner ear cell regeneration from stem/progenitor cells provides potential therapeutic strategies for the restoration of sensorineural hearing loss (SNHL), however, the efficiency of regeneration is low and the functions of differentiated cells are not yet mature. Biomaterials have been used in inner ear cell regeneration to construct a more physiologically relevant 3D culture system which mimics the stem cell microenvironment and facilitates cellular interactions. Currently, these biomaterials include hydrogel, conductive materials, magneto-responsive materials, photo-responsive materials, etc. We analyzed the characteristics and described the advantages and limitations of these materials. Furthermore, we reviewed the mechanisms by which biomaterials with different physicochemical properties act on the inner ear cell regeneration and depicted the current status of the material selection based on their characteristics to achieve the reconstruction of the auditory circuits. The application of biomaterials in inner ear cell regeneration offers promising opportunities for the reconstruction of the auditory circuits and the restoration of hearing, yet biomaterials should be strategically explored and combined according to the obstacles to be solved in the inner ear cell regeneration research.

Intraoperative Difficulties and Postoperative Complications Associated With Cochlear Implantations: A Study From Erbil City

Background and objective Cochlear implants are highly effective for the treatment of severe to profound hearing loss. Cochlear implant surgery is a safe surgical procedure; however, due to many modifications over the years, it has been associated with certain minor and major complications. This study aimed to examine the intraoperative difficulties and postoperative complications in patients who received cochlear implants in Erbil City. Methods We conducted a retrospective descriptive study regarding complications of cochlear implants involving patients who received unilateral or bilateral cochlear Implants at the Rizgary Teaching Hospital and a private hospital in Erbil City from January 2013 to July 2022. Their medical records were analyzed, and data on demographics, intraoperative difficulties, and postoperative complications were gathered. Results A total of 160 patients with cochlear implants (87 male, 54.4%; 73 female, 45.6%) were included in the study. The mean age of the patients at the time of operation was 6.76 ± 8.02 years (range: 1-53 years); 150 of these patients were children and 10 were adults (18 years and above). Intraoperative difficulties occurred in five patients (3.1%). The overall rate of complication was 10%, 7.5% of which was minor (the most common being wound infection) and 2.5% major (the most frequent being device extrusion). Conclusions Cochlear implant surgery is a safe procedure performed to treat profoundly deaf patients. It is associated with a low rate of complications, most of which can be successfully managed with conservative measures or minimal intervention.

Are children with unilateral sensorineural hearing loss receiving cochlear implants?

INTRODUCTION

The US Food and Drug Administration (FDA) granted its first approval for cochlear implants (CI) in children with bilateral sensorineural hearing loss (SNHL) in 1990. In 2019, the FDA expanded CI indications to include children with unilateral SNHL.

OBJECTIVE

The aim of this study was to assess the prevalence of children with unilateral SNHL in the population of new pediatric CI recipients between 2012 and 2021.

METHODS

A retrospective analysis using the American College of Surgeons National Surgical Quality Improvement Pediatric database examined patients under 18 years of age with bilateral or unilateral SNHL who underwent CI between 2012 and 2021. Current Procedural Terminology code 69930 identified patients with 'cochlear device implantation, with or without mastoidectomy.' The percentage of children undergoing CI for unilateral versus bilateral SNHL during the study period was calculated and subjected to statistical analysis.

RESULTS

9863 pediatric CI patients were included with a mean age of 5.1 (95 % CI 5.1-5.2) years at the time of implantation. 7.5 % (N = 739) of patients had unilateral SNHL and 92.5 % (N = 9124) had bilateral SNHL. Children with bilateral SNHL undergoing CI were significantly younger (5.0 years versus 6.9 years for those with unilateral SNHL, p < .001). There was a statistically significant difference in the percentage of children receiving CI for unilateral versus bilateral SNHL (3.3 % in 2012 to 14.3 % in 2021, p < .001) before and after the FDA changes.

CONCLUSIONS

The proportion of CIs placed for unilateral SNHL has increased annually even before 2019 when the FDA expanded its CI indications to include children with unilateral SNHL for the first time.

Prognostic factors in pediatric cochlear implant: an outcome-based study

OBJECTIVE

To determine the prognostic factors in the pediatric cochlear implant (CI) outcome.

MATERIALS AND METHODS

This prospective cohort study was conducted on 289 pediatric cases with prelingual hearing loss who received cochlear implantation. Several possible salient factors have been recorded. Auditory and speech evaluations were performed before CI, as well as 6 and 12 months after surgery, using Categories of Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) tests.

RESULTS

According to univariate analysis, age at the time of surgery was a statistically significant factor. Neurological problems in the child, history of newborn infectious diseases, history of hearing aid use, proper parental cooperation, and round window approach were all significantly related to better auditory or speech outcomes. On the other hand, good parental cooperation and age (for CAP) and good parental cooperation, age, history of infectious disease, and hearing aids use (for SIR) are the significant factors in the multivariate setting.

CONCLUSION

As evidenced by the obtained results, age, background diseases, history of rehabilitation with hearing aids, and surgical details are essential factors to be taken into account in the case-selection process.

The Role of Imaging Investigations in Evaluation of Cochlear Dimensions in Candidates for Cochlear Implantation-Our Experience

Background and Objectives: The Cochlear implant is the first approved cranial nerve stimulator that works by directly stimulating the cochlear nerve. Various attempts have been made to evaluate the dimensions of the cochlea related to cochlear implantation. The preoperative computed tomographic examination is essential not only in assessing the anatomical aspect of the cochlea, but also in determining its dimensions to choose an appropriate electrode and obtain the best possible audiological performance. Materials and Methods: In the present paper, we aimed to carry out an observational study regarding the role of cochlear measurements in the preoperative evaluation of patients proposed for cochlear implants. The purpose of the study was to measure the cochlea and establish the existence of a correlation between the size of the cochlea and the age and gender of the patients. Results: From the group of 35 examined patients, 54% (n = 19) were male and 46% (n = 16) were female. The average length of the cochlea in the age group 0-4 years is 7.82 mm in the left ear and 7.86 mm in the right ear; in the age group 4-7 years, it is 7.82 mm and 7.94 mm, respectively; for the age group 7-14 years, the dimensions increase to 8.48 mm and 8.77 mm, respectively; and after 14 years, these dimensions reach 9.12 mm and 9.18 mm, respectively. Comparative measurements of the length of the cochlea by age groups show an increase in length with the patient's age, but this increase does not exceed 1.5 mm for both the right and left ears. The measurements of the width of the cochlea, by age group, start from 6.84 mm in the left ear and 6.81 mm in the right ear at 0-4 years, 6.94 mm and 6.97 mm, respectively, in the group 4-7 years, 7.71 mm and 7.55 mm at 7-14 years, and reaching 8.19 mm and 8.12 mm at the age of 14 years and over. Conclusions: From the study carried out, it can be concluded that the evaluation of the dimensions of the cochlea is important for cochlear implantation. The size variables, although small, are still an element to be considered in correlation with the age of the patient and the implanted ear. This increase is statistically insignificant, but it still exists, even if, from a theoretical point of view, it is considered that the dimensions of the cochlea remain constant.

Photobiomodulation Can Enhance Stem Cell Viability in Cochlea with Auditory Neuropathy but Does Not Restore Hearing

Sensorineural hearing loss is very difficult to treat. Currently, one of the techniques used for hearing rehabilitation is a cochlear implant that can transform sound into electrical signals instead of inner ear hair cells. However, the prognosis remains very poor if sufficient auditory nerve cells are not secured. In this study, the effect of mouse embryonic stem cells (mESC) and photobiomodulation (PBM) combined treatment on auditory function and auditory nerve cells in a secondary neuropathy animal model was investigated. To confirm the engraftment of stem cells in vitro, cochlear explants were treated with kanamycin (KM) to mimic nerve damage and then cocultured with GFP-mESC. GFP-mESCs were observed to have attached and integrated into the explanted samples. An animal model for secondary neurodegeneration was achieved by KM treatment and was treated by a combination therapy of GFP-mESC and NIR-PBM at 8 weeks of KM treatment. Hearing recovery by functional testing using auditory brain stem response (ABR) and eABR was measured as well as morphological changes and epifluorescence analysis were conducted after 2 weeks of combination therapy. KM treatment elevated the hearing threshold at 70-80 dB and even after the combination treatment with GFP-mESC and PBM was applied, the auditory function was not restored. In addition, the stem cells transplanted into cochlea has exponentially increased due to PBM treatment although did not produce any malignancy. This study confirmed that the combined treatment with mESC and PBM could not improve hearing or increase the response of the auditory nerve. Nevertheless, it is noteworthy in this study that the cells are distributed in most cochlear tissues and the proliferation of stem cells was very active in animals irradiated with PBM compared to other groups wherein the stem cells had disappeared immediately after transplantation or existed for only a short period of time.

Emotions and Psychological Mechanisms of Listening to Music in Cochlear Implant Recipients

OBJECTIVES

Music is a multidimensional phenomenon and is classified by its arousal properties, emotional quality, and structural characteristics. Although structural features of music (i.e., pitch, timbre, and tempo) and music emotion recognition in cochlear implant (CI) recipients are popular research topics, music-evoked emotions, and related psychological mechanisms that reflect both the individual and social context of music are largely ignored. Understanding the music-evoked emotions (the "what") and related mechanisms (the "why") can help professionals and CI recipients better comprehend the impact of music on CI recipients' daily lives. Therefore, the purpose of this study is to evaluate these aspects in CI recipients and compare their findings to those of normal hearing (NH) controls.

DESIGN

This study included 50 CI recipients with diverse auditory experiences who were prelingually deafened (deafened at or before 6 years of age)-early implanted (N = 21), prelingually deafened-late implanted (implanted at or after 12 years of age-N = 13), and postlingually deafened (N = 16) as well as 50 age-matched NH controls. All participants completed the same survey, which included 28 emotions and 10 mechanisms (Brainstem reflex, Rhythmic entrainment, Evaluative Conditioning, Contagion, Visual imagery, Episodic memory, Musical expectancy, Aesthetic judgment, Cognitive appraisal, and Lyrics). Data were presented in detail for CI groups and compared between CI groups and between CI and NH groups.

RESULTS

The principal component analysis showed five emotion factors that are explained by 63.4% of the total variance, including anxiety and anger, happiness and pride, sadness and pain, sympathy and tenderness, and serenity and satisfaction in the CI group. Positive emotions such as happiness, tranquility, love, joy, and trust ranked as most often experienced in all groups, whereas negative and complex emotions such as guilt, fear, anger, and anxiety ranked lowest. The CI group ranked lyrics and rhythmic entrainment highest in the emotion mechanism, and there was a statistically significant group difference in the episodic memory mechanism, in which the prelingually deafened, early implanted group scored the lowest.

CONCLUSION

Our findings indicate that music can evoke similar emotions in CI recipients with diverse auditory experiences as it does in NH individuals. However, prelingually deafened and early implanted individuals lack autobiographical memories associated with music, which affects the feelings evoked by music. In addition, the preference for rhythmic entrainment and lyrics as mechanisms of music-elicited emotions suggests that rehabilitation programs should pay particular attention to these cues.

A Five-Decade Text Mining Analysis of Cochlear Implant Research: Where We Started and Where We Are Heading

Background and Objectives: Since its invention in the 1970s, the cochlear implant (CI) has been substantially developed. We aimed to assess the trends in the published literature to characterize CI. Materials and Methods: We queried PubMed for all CI-related entries published during 1970-2022. The following data were extracted: year of publication, publishing journal, title, keywords, and abstract text. Search terms belonged to the patient's age group, etiology for hearing loss, indications for CI, and surgical methodological advancement. Annual trends of publications were plotted. The slopes of publication trends were calculated by fitting regression lines to the yearly number of publications. Results: Overall, 19,428 CIs articles were identified. Pediatric-related CI was the most dominant sub-population among the age groups, with the highest rate and slope during the years (slope 5.2 ± 0.3, p < 0.001), while elderly-related CIs had significantly fewer publications. Entries concerning hearing preservation showed the sharpest rise among the methods, from no entries in 1980 to 46 entries in 2021 (slope 1.7 ± 0.2, p < 0.001). Entries concerning robotic surgery emerged in 2000, with a sharp increase in recent years (slope 0.5 ± 0.1, p < 0.001). Drug-eluting electrodes and CI under local-anesthesia have been reported only in the past five years, with a gradual rise. Conclusions: Publications regarding CI among pediatrics outnumbered all other indications, supporting the rising, pivotal role of CI in the rehabilitation of children with sensorineural hearing loss. Hearing-preservation publications have recently rapidly risen, identified as the primary trend of the current era, followed by a sharp rise of robotic surgery that is evolving and could define the next revolution.

High-Precision 3D Printing of Microporous Cochlear Implants for Personalized Local Drug Delivery

Hearing loss is a highly prevalent multifactorial disorder affecting 20% of the global population. Current treatments using the systemic administration of drugs are therapeutically ineffective due to the anatomy of the cochlea and the existing blood-labyrinth barrier. Local drug delivery systems can ensure therapeutic drug concentrations locally while preventing adverse effects caused by high dosages of systemically administered drugs. Here, we aimed to design, fabricate, and characterize a local drug delivery system for the human cochlea. The design was relevant to the size of the human ear, included two different shapes, and incorporated two different microporous structures acting as reservoirs for drug loading and release. The four cochlear implant designs were printed using the two-photon polymerization (2PP) technique and the IP-Q photoresist. The optimized 2PP process enabled the fabrication of the cochlear implants with great reproducibility and shape fidelity. Rectangular and cylindrical implants featuring cylindrical and tapered tips, respectively, were successfully printed. Their outer dimensions were 0.6 × 0.6 × 2.4 mm3 (L × W × H). They incorporated internal porous networks that were printed with high accuracy, yielding pore sizes of 17.88 ± 0.95 μm and 58.15 ± 1.62 μm for the designed values of 20 μm and 60 μm, respectively. The average surface roughness was 1.67 ± 0.24 μm, and the water contact angle was 72.3 ± 3.0°. A high degree of polymerization (~90%) of the IP-Q was identified after printing, and the printed material was cytocompatible with murine macrophages. The cochlear implants designed and 3D printed in this study, featuring relevant sizes for the human ear and tunable internal microporosity, represent a novel approach for personalized treatment of hearing loss through local drug delivery.

Dynamic Range and Neural Response Threshold in Cochlear Implant Mapping Can Be Useful in Predicting Prognosis Related to Postoperative Speech Perception

BACKGROUND AND OBJECTIVES

To analyze mapping changes in dynamic range (DR) and neural response threshold (NRT) as prognostic factors for cochlear implant (CI). To analyze whether postoperative speech perception performance could be predicted using DR change and initial NRT.

SUBJECTS AND METHODS

The speech comprehension data of 33 patients with CI were retrospectively analyzed after 1, 3, 6, and 12 months of device use. All subjects were adult, postlingually hearing-impaired, and Cochlear Nucleus CI users. Speech perception performance was evaluated using aided pure tone audiometry, consonant, vowel, one-word, two-word, and sentence tests.

RESULTS

The averages of initial NRT and DR changes were 197.8±25.9 CU (104-236) and 22.2±18.4 CU (-15-79), respectively. The initial DR was 40.8±16.6 CU. The postoperative DR was 50.3±16.4 CU at 3 months, 58±12.3 CU at 6 months, and 62.9±10.4 CU at 12 months. A gradual increase of DR was observed during the first year of CI. Compared with the initial DR, significant increases in DR were observed at 3 (p<0.05), 6 (p<0.001), and 12 (p<0.001) months. Compared with initial speech performance outcomes, a significant gain in all performance outcomes was achieved at 12 months (p<0.001).

CONCLUSIONS

Patients with low NRT after CI surgery could initially set DR to a wider range and had better final speech perception outcomes. Conversely, patients with high NRT after CI surgery had to set up a gradual increase in DR while adjusting the T-C level, and the final speech perception outcomes were worse. DR and NRT, the main CI mapping variables, can help predict prognosis related to speech perception outcomes after CI surgery. In conclusion, the post-CI speech perception is better with a lower initial NRT, wider final DR, or younger age.

Interactions between cathodic- and anodic-pulses during high-frequency stimulations with the monophasic-pulses alternating in polarity at axons-experiment and simulation studies

Background. Electrical neuromodulation therapies commonly utilize high-frequency stimulations (HFS) of biphasic-pulses to treat neurological disorders. The biphasic pulse consists of a leading cathodic-phase to activate neurons and a lagging anodic-phase to balance electrical charges. Because both monophasic cathodic- and anodic-pulses can depolarize neuronal membranes, splitting biphasic-pulses into alternate cathodic- and anodic-pulses could be a feasible strategy to improve stimulation efficiency.Objective. We speculated that neurons in the volume initially activated by both polarity pulses could change to be activated only by anodic-pulses during sustained HFS of alternate monophasic-pulses. To verify the hypothesis, we investigated the interactions of the monophasic pulses during HFS and revealed possible underlying mechanisms.Approach. Different types of pulse stimulations were applied at the alvear fibers (i.e. the axons of CA1 pyramidal neurons) to antidromically activate the neuronal cell bodies in the hippocampal CA1 region of anesthetized ratsin-vivo. Sequences of antidromic HFS (A-HFS) were applied with alternate monophasic-pulses or biphasic-pulses. The pulse frequency in the A-HFS sequences was 50 or 100 Hz. The A-HFS duration was 120 s. The amplitude of antidromically-evoked population spike was measured to evaluate the neuronal firing induced by each pulse. A computational model of axon was used to explore the possible mechanisms of neuronal modulations. The changes of model variables during sustained A-HFS were analyzed.Main results. In rat experiments, with a same pulse intensity, the activation volume of a cathodic-pulse was greater than that of an anodic-pulse. In paired-pulse tests, a preceding cathodic-pulse was able to prevent a following anodic-pulse from activating neurons due to refractory period. This indicated that the activation volume of a cathodic-pulse covered that of an anodic-pulse. However, during sustained A-HFS of alternate monophasic-pulses, the anodic-pulses were able to prevail over the cathodic-pulses in activating neurons in the overlapped activation volume. Model simulation results show the mechanisms of the activation failures of cathodic-pulses. They include the excessive membrane depolarization caused by an accumulation of potassium ions, the obstacle of hyperpolarization in the conduction pathway and the interactions from anodic-pulses.Significance. The study firstly showed the domination of anodic-pulses over cathodic-pulses in their competitions to activate neurons during sustained HFS. The finding provides new clues for designing HFS paradigms to improve the efficiency of neuromodulation therapies.

Association of age-related hearing loss with cognitive impairment and dementia: an umbrella review

Background

Hearing loss, cognitive impairment and dementia have become common problems for older adults. Currently, systematic reviews and meta-analyses of the association between age-related hearing loss (ARHL) with cognitive impairment and dementia may have inconsistent results. To explore and validate the association between ARHL with cognitive impairment and dementia through summarizing and evaluating existing evidence.

Methods

From inception to February 01, 2023, PubMed, Web of Science, Embase, and Cochrane Library databases were systematically searched. AMSTAR 2 was used to evaluate methodological quality and GRADE system was used to evaluate evidence quality. We summarized the basic characteristics of the included studies and extracted effect data for ARHL with cognitive impairment and dementia. Forest plots were used to describe the relative risk associated with ARHL and cognitive impairment, and the relative risk associated with ARHL and dementia, respectively.

Results

A total of 11 systematic reviews and meta-analyses met the inclusion criteria. Overall, the methodological quality of the included SRs/MAs was moderate and the quality of the evidence was low. The combined results found that the pooled risk ratio of ARHL and cognitive impairment was 1.30 (random-effects; 95% CI 1.16 to 1.45), and the pooled risk ratio of ARHL and dementia was 1.59 (random-effects; 95% CI 1.34 to 1.90).

Conclusion

Based on the evidence reported in this umbrella review, age-related hearing loss is significantly associated with cognitive impairment and dementia. Hearing loss may be a high risk factor for cognitive impairment and dementia in older adults.

The Impact of Patient Factors on Objective Cochlear Implant Verification Using Acoustic Cortical Auditory-Evoked Potentials

INTRODUCTION

Hearing loss is a major global public health issue that negatively impacts quality of life, communication, cognition, social participation, and mental health. The cochlear implant (CI) is the most efficacious treatment for severe-to-profound sensorineural hearing loss. However, variability in outcomes remains high among CI users. Our previous research demonstrated that the existing subjective methodology of CI programming does not consistently produce optimal stimulation for speech perception, thereby limiting the potential for CI users to derive the maximum device benefit to achieve their peak potential. We demonstrated the benefit of utilising the objective method of measuring auditory-evoked cortical responses to speech stimuli as a reliable tool to guide and verify CI programming and, in turn, significantly improve speech perception performance. The present study was designed to investigate the impact of patient- and device-specific factors on the application of acoustically-evoked cortical auditory-evoked potential (aCAEP) measures as an objective clinical tool to verify CI mapping in adult CI users with bilateral deafness (BD).

METHODS

aCAEP responses were elicited using binaural peripheral auditory stimulation for four speech tokens (/m/, /g/, /t/, and /s/) and recorded by HEARLab™ software in adult BD CI users. Participants were classified into groups according to subjective or objective CI mapping procedures to elicit present aCAEP responses to all four speech tokens. The impact of patient- and device-specific factors on the presence of aCAEP responses and speech perception was investigated between participant groups.

RESULTS

Participants were categorised based on the presence or absence of the P1-N1-P2 aCAEP response to speech tokens. Out of the total cohort of adult CI users (n = 132), 63 participants demonstrated present responses pre-optimisation, 37 participants exhibited present responses post-optimisation, and the remaining 32 participants either showed an absent response for at least one speech token post-optimisation or did not accept the optimised CI map adjustments. Overall, no significant correlation was shown between patient and device-specific factors and the presence of aCAEP responses or speech perception scores.

CONCLUSION

This study reinforces that aCAEP measures offer an objective, non-invasive approach to verify CI mapping, irrespective of patient or device factors. These findings further our understanding of the importance of personalised CI rehabilitation through CI mapping to minimise the degree of speech perception variation post-CI and allow all CI users to achieve maximum device benefit.

Triamcinolone Injection for Cochlear Implant Magnet Adherence Issues

OBJECTIVES

To evaluate the effectiveness of triamcinolone injections in treating external magnet displacement in cochlear implant (CI) patients with adhesions problems of their processor.

PATIENTS

We present seven CI patients with magnet adhesion issues who presented to our tertiary care neurotology clinic. None of the patients had a history of head trauma, postimplant MRI, or surgery in the head and neck other than the cochlear implantation.

INTERVENTION

Triamcinolone 40 mg/mL injected subcutaneously at the CI magnet site.

MAIN OUTCOME MEASURE

Reduction of scalp thickness and successful magnet retention.

RESULTS

Our cohort consisted of seven patients (eight implant sites) of which five were overweight or obese. The temporoparietal scalp thickness measured on preoperative CT scans varied between 8.4 and 15.9 mm. Initial conservative measures such as hair shaving at the magnet site, using a headband, and increasing magnet strength failed in all patients. After receiving triamcinolone injections at the CI receiver site, six out of seven patients (seven out of eight CI sites) were able to use their processor again without the need for a headband for an average of 9.55 hours/day. The average number of injections required for each patient was 2.57 (SD = 2.18), median (range) = 1 (1-7). One patient required a flap thinning surgery but showed no improvement even after flap thinning. None of the patients showed skin irritation, breakdown, ulceration, necrosis, or magnet exposure during follow-up period.

CONCLUSIONS

The significant improvement in CI retention shows that triamcinolone injections are effective in making the subcutaneous tissue thinner and allowing magnet retention.

Using x-ray micro computed tomography to quantify intracochlear fibrosis after cochlear implantation in a Guinea pig model

Cochlear implants (CIs) allow individuals with profound hearing loss to understand speech and perceive sounds. However, not all patients obtain the full benefits that CIs can provide and the cause of this disparity is not fully understood. One possible factor for the variability in outcomes after cochlear implantation, is the development of fibrotic scar tissue around the implanted electrode. It has been hypothesised that limiting the extent of fibrosis after implantation may improve overall CI function, and longevity of the device. Currently, histology is often used to quantify the extent of intracochlear tissue growth after implantation however this method is labour intensive, time-consuming, often involves significant user bias, and causes physical distortion of the fibrosis. Therefore, this study aimed to evaluate x-ray micro computed tomography (μCT) as a method to measure the amount and distribution of fibrosis in a guinea pig model of cochlear implantation. Adult guinea pigs were implanted with an inactive electrode, and cochleae harvested eight weeks later (n = 7) and analysed using μCT, to quantify the extent of tissue reaction, followed by histological analysis to confirm that the tissue was indeed fibrotic. Cochleae harvested from an additional six animals following implantation were analysed by μCT, before and after contrast staining with osmium tetroxide (OsO4), to enhance the visualisation of soft tissues within the cochlea, including the tissue reaction. Independent analysis by two observers showed that the quantification method was robust and provided additional information on the distribution of the response within the cochlea. Histological analysis revealed that μCT visualised dense collagenous material and new bone formation but did not capture loose, areolar fibrotic tissue. Treatment with OsO4 significantly enhanced the visible tissue reaction detected using μCT. Overall, μCT is an alternative and reliable method that can be used to quantify the extent of the CI-induced intracochlear tissue response and will be a useful tool for the in vivo assessment of novel anti-fibrotic treatments.

Health Utilities of Bilateral Severe-to-Profound Hearing Loss with Assistive Devices

Hearing loss is a common sensory disorder in newborns. Early intervention with assistive devices benefits children's auditory and speech performance. This study aimed to measure the health utilities of children with bilateral severe-to-profound hearing impairment with different assistive devices. The descriptions of four hypothetical health states were developed, and their utility values were obtained from healthcare professionals via the visual analogue scale (VAS) and time trade-off (TTO) methods. Thirty-seven healthcare professionals completed the TTO interview and were included in the analysis. The mean utility scores obtained via VAS were 0.31 for no assistive devices, 0.41 for bilateral hearing aids, 0.63 for bimodal hearing, and 0.82 for bilateral cochlear implants. As for the utility scores obtained via TTO, mean values were 0.60, 0.69, 0.81, and 0.90, respectively. None of the four groups had the same VAS- or TTO-elicited utility (p < 0.001). The post hoc test results showed that the difference was significant between any two groups (all p < 0.05). In conclusion, this study elicited health utility of bilateral hearing impairment with different assistive devices using the VAS and TTO methods. The utility values obtained provide critical data for future cost-utility analysis and health technology assessment.

The Influence of Activities and Functional Social Support on Adult Cochlear Implant Outcomes

Objective

The objective of this study is to assess whether patient participation in specific activities and perceived social support correlate with speech perception following cochlear implantation.

Setting

Tertiary referral hospital.

Methods

Adult cochlear implantation patients implanted in their poorer hearing ear between January 2019 and December 2020 completed the Functional Social Support Questionnaire (FSSQ) and a modified version of the Victoria Lifestyle Study-Activities Lifestyle Questionnaire (VLS-ALQ). Demographics, FSSQ score, and individual activities were correlated with implanted ear and binaural AzBio scores.

Results

Twenty-three patients completed the survey and had at least 6 months of follow-up with appropriate speech perception testing. The average age at survey completion was 71.7 (SD, 9.1). Average pure-tone average in the contralateral ear was 70.1 (SD: 20) dB. The majority (N = 21, 91.3%) wore a hearing aid in the contralateral ear following cochlear implantation. Mean AzBioQuiet score improvement was 60.6% (range: 20%-99%) in the implanted ear and 42.6% (range: -2% to 67%) binaurally. Work-related social support correlated positively with improvement in the implanted ear (Pearson's R = 0.473; 95% CI, 0.075-0.741; P = 0.023). Improvement in the implanted ear correlated positively with creative writing (R = 0.542; 95% CI, 0.167-0.780; P = 0.008), attending films (R = 0.448; 95% CI, 0.044-0.726; P = 0.032), going out with friends (R = 0.423; 95% CI, 0.013-0.711; P = 0.044) listening to audiobooks (R = 0.433; 95% CI, 0.025-0.717; P = 0.039), and public speaking (R = 0.468; 95% CI, 0.069-0.738; P = 0.024). Gains in binaural performance correlated positively with watching TV news (R = 0.819; 95% CI, 0.509-0.941; P < 0.001) and negatively with eating at restaurants (R = -0.532; 95% CI, -0.829 to -0.002; P = 0.05).

Conclusions

Activities that provide intellectual stimulation and engage auditory faculties correlate with greater speech perception testing improvements in adult cochlear implantation patients.

Interobserver variability of cochlear duct measurements in pediatric cochlear implant candidates

PURPOSE

The objective of the study was to evaluate the proposed cochlear duct length estimation based on the cochlear 'A value'. Furthermore, we assessed the interobserver variability between radiology and otolaryngology attending physicians and otolaryngology trainees.

METHODS

Thirteen pediatric cochlear implant candidates were retrospectively analyzed by three otolaryngology physicians (attending physician, second year, and fourth year trainees) and a radiology attending. The cochlear duct length was calculated based on the formula of Grover et al. The differences in acquired measurements between observers were compared using the Wilcoxon matched signed-rank test.

RESULTS

The differences in measurements between the attending otolaryngologist and radiologist were not statistically different, while several significant differences were observed with regard to measurements of attending doctors compared to both residents. In particular, a significant difference between the second year otolaryngology resident and otolaryngology and radiology attending was observed for one side (right ear p = 0.034 and p = 0.012, respectively). Moreover, the fourth year resident calculated significantly different cochlear duct measurements when compared to the attending otolaryngologist (left ear p = 0.014) and radiologist (right ear p = 0.047). Interestingly, differently experienced otolaryngology residents provided significantly different measurements for both ears.

CONCLUSIONS

Based on these results, cochlear duct length measurement according to the proposed method may be a reliable and cost-effective method. Indeed, otolaryngology training may be sufficient to provide measurements comparable to radiologists. On the other hand, additional efforts should be invested during otolaryngology training in terms of the evaluation of radiological imaging which may increase the capabilities of otolaryngology residents in this regard.

Health-Related Quality of Life and Work Satisfaction in Working-Aged Adults Pre- and Post-Cochlear Implant: A Longitudinal Study

Hearing loss is a growing public health concern associated with decreased health-related quality of life (HRQoL) and a negative impact on work life. Knowledge about the long-term benefits for patients receiving cochlear implants may provide knowledge imperative for policymakers to promote better HRQoL and working life outcomes for individuals with hearing loss. The purpose of this study was to explore how HRQoL, hearing disabilities, and work satisfaction outcomes changed in working-aged adults with severe to profound hearing loss from pre- to post-receiving a cochlear implant (CI) between the baseline, year one, and year two. This longitudinal study used Cochlear's Implant Recipient Observational Study (IROS) registry data to assess HRQoL, hearing disabilities, and work satisfaction in 18-65-year-old CI recipients. Data were collected pre- and post-implantation at baseline, year one, and year two follow-up. One hundred and twenty-seven CI recipients participated in the study. Significant improvements were observed for HRQoL outcomes for hearing, speech, emotion, and health utility post-implant. Overall hearing disability decreased post-CI, and work satisfaction improved. With the increasing prevalence of hearing disabilities, this is pertinent knowledge that supports the use of CIs for hearing rehabilitation which may promote better HRQoL and work satisfaction.

Activation region overlap visualization for image-guided cochlear implant programming

Objective. The cochlear implant is a neural prosthesis designed to directly stimulate auditory nerve fibers to induce the sensation of hearing in those experiencing severe-to-profound hearing loss. After surgical implantation, audiologists program the implant's external processor with settings intended to produce optimal hearing outcomes. The likelihood of achieving optimal outcomes increases when audiologists have access to tools that objectively present information related to the patient's own anatomy and surgical outcomes. This includes visualizations like the one presented here, termed the activation region overlap image, which is designed to decrease subjectivity when determining amounts of overlapping stimulation between implant electrodes.Approach. This visualization uses estimates of electric field strength to indicate spread of neural excitation due to each electrode. Unlike prior visualizations, this method explicitly defines regions of nerves receiving substantial stimulation from each electrode to help clinicians assess the presence of significant overlapping stimulation. A multi-reviewer study compared this and an existing technique on the consistency, efficiency, and optimality of plans generated from each method. Statistical significance was evaluated using the two-sided Wilcoxon rank sum test.Main results. The study showed statistically significant improvements in consistency (p < 10-12), efficiency (p < 10-15), and optimality (p < 10-5) when generating plans using the proposed method versus the existing method.Significance. This visualization addresses subjectivity in assessing overlapping stimulation between implant electrodes, which currently relies on reviewer estimates. The results of the evaluation indicate the provision of such objective information during programming sessions would likely benefit clinicians in making programming decisions.

Can cochlear implantation prevent cognitive decline in the long-term follow-up?

Cognitive function and hearing are known to both decline in older adults. As hearing loss is proposed to be one modifiable risk factor for dementia, the impact of auditory rehabilitation on cognitive decline has been gaining increasing attention. Despite a large number of studies, long-term data are still rare. In a large prospective longitudinal monocentric study, 50 adults (aged ≥ 50 years) with severe postlingual bilateral hearing loss received a cochlear implant (CI). They underwent comprehensive neurocognitive testing prior to implantation (T1), at 12 months (T2) and up to 65 months (T3) after implantation. Various cognitive subdomains such as attention, inhibition, working memory, verbal fluency, mental flexibility and (delayed) recall were assessed by the computer-based non-auditory test battery ALAcog©. The observed trajectories of two exemplary cognitive subdomains (delayed recall and working memory) were then fitted over time using multilevel growth models to adjust for sociodemographic covariates and compared with 5-year longitudinal data from a sample of older adults from the representative Survey of Health, Aging and Retirement in Europe (SHARE) study. Postoperatively, auditory functions improved from 6.98% (SD 12.83) to 57.29% (SD 20.18) in monosyllabic speech understanding. Cognitive functions significantly increased from T1 to T3 in attention (p = 0.001), delayed recall (p = 0.001), working memory (OSPAN; p = 0.001), verbal fluency (p = 0.004), and inhibition (p = 0.002). A closer look at follow-up revealed that cognitive improvement could be detected between T1 and T2 and thereafter remained stable in all subtests (p ≥ 0.06). Additional longitudinal analysis confirmed these findings in a rigorous multilevel approach in two exemplary cognitive subdomains. In contrast to the SHARE data, there was no evidence for age-differential associations over time in CI recipients. This suggests that older adults benefit equally from cochlear implantation. CI users with worse preoperative cognitive skills experienced the most benefit (p < 0.0001). Auditory rehabilitation by cochlear implantation has a stimulating effect on cognitive functions beyond an improvement in speech understanding and an increased well-being. Large multicenter studies using standardized protocols have to be undertaken in the future to find out whether hearing restoration might help to prevent cognitive decline.

Advancements in inner ear development, regeneration, and repair through otic organoids

The vertebrate inner ear contains a diversity of unique cell types arranged in a particularly complex 3D cytoarchitecture. Both of these features are integral to the proper development, function, and maintenance of hearing and balance. Since the elucidation of the timing and delivery of signaling molecules to produce inner ear sensory cells, supporting cells, and neurons from human induced pluripotent stem cells, we have entered a revolution using organ-like 'otic organoid' cultures to explore inner ear specific genetic programs, developmental rules, and potential therapeutics. This review aims to highlight a selection of reviews and primary research papers from the past two years of particular merit that use otic organoids to investigate the broadly defined topics of cell reprogramming, regeneration, and repair.

Image-Guided Cochlear Implant Programming: A Systematic Review and Meta-analysis

OBJECTIVE

To review studies evaluating clinically implemented image-guided cochlear implant programing (IGCIP) and to determine its effect on cochlear implant (CI) performance.

DATA SOURCES

PubMed, EMBASE, and Google Scholar were searched for English language publications from inception to August 1, 2021.

STUDY SELECTION

Included studies prospectively compared intraindividual CI performance between an image-guided experimental map and a patient's preferred traditional map. Non-English studies, cadaveric studies, and studies where imaging did not directly inform programming were excluded.

DATA EXTRACTION

Seven studies were identified for review, and five reported comparable components of audiological testing and follow-up times appropriate for meta-analysis. Demographic, speech, spectral modulation, pitch accuracy, and quality-of-life survey data were collected. Aggregate data were used when individual data were unavailable.

DATA SYNTHESIS

Audiological test outcomes were evaluated as standardized mean change (95% confidence interval) using random-effects meta-analysis with raw score standardization. Improvements in speech and quality-of-life measures using the IGCIP map demonstrated nominal effect sizes: consonant-nucleus-consonant words, 0.15 (-0.12 to 0.42); AzBio quiet, 0.09 (-0.05 to 0.22); AzBio +10 dB signal-noise ratio, 0.14 (-0.01 to 0.30); Bamford-Kowel-Bench sentence in noise, -0.11 (-0.35 to 0.12); Abbreviated Profile of Hearing Aid Benefit, -0.14 (-0.28 to 0.00); and Speech Spatial and Qualities of Hearing Scale, 0.13 (-0.02 to 0.28). Nevertheless, 79% of patients allowed to keep their IGCIP map opted for continued use after the investigational period.

CONCLUSION

IGCIP has potential to precisely guide CI programming. Nominal effect sizes for objective outcome measures fail to reflect subjective benefits fully given discordance with the percentage of patients who prefer to maintain their IGCIP map.

Influence of cochlear implants on hearing-related quality of life: results from Chinese children with cochlear implants entering mainstream education

OBJECTIVES

This study aimed to 1) assess the hearing-related Quality of Life (QoL) of children with cochlear implants (CIs) in China and 2) investigate the impact of CI in children and of the socio-demographic backgrounds of their guardians on the hearing-related QoL of children with CIs in the Chinese mainstream education system.

METHODS

This study used the Mandarin Children with Cochlear Implants: Parental Perspectives questionnaire (MPP), which assessed the communication capability, auditory perception, self-independence, level of happiness with family, social interaction, academic performance, outcome assessment for CI, and level of family support in children with CIs. Both univariate and multiple linear regression analyses were performed to identify the relationship of CI in children and the socio-demographic backgrounds of their guardians with hearing-related QoL in children with CI.

RESULT

A total of 124 responses were collected, and they indicated satisfaction and improvement across all aspects of the MPP Questionnaire. Statistical analysis revealed that an earlier age of cochlear implantation (≤3 years old) could improve the communication capabilities, self-independence, social interaction performance, and academic performance of children with CIs. In addition, children with CI from the urban regions demonstrated better social interaction performance than that by those from the rural regions of China.

CONCLUSION

CIs can improve hearing-related QoL in children with pre-lingual or congenital hearing loss entering the mainstream education system in China. This study showed that early age of cochlear implantation was critical for successful long-term auditory development and academic achievement in children with CIs in China. Therefore, healthcare professionals and educators in China should advocate for CI for children with severe congenital or pre-lingual hearing loss.

Poly-D,L-lactic acid polymer and cochlear implantation

This case report describes a peculiar and innovative fixing procedure with a Poly-D,L-lactic acid (PDLLA) polymer in the unusual case of magnet dislodgment and rupture of the cochlear implant (CI) silicone sheath holding the magnet.

Longitudinal Speech Recognition Changes After Cochlear Implant: Systematic Review and Meta-analysis

OBJECTIVES

To examine patterns of change and plateau in speech recognition scores in postlingually hearing impaired adult cochlear implant recipients. The study also examines variations in change patterns for different speech materials and testing conditions.

STUDY DESIGN

Used systematic review with meta-analysis.

METHODS

Articles in English reporting speech recognition scores of adults with postlingual hearing loss at pre-implantation and at least two post-implantation time points were included. Statistically significant changes were determined by meta-analysis and the 95% confidence interval.

RESULTS

A total of 22 articles representing 1954 patients were included. Meta-analysis of mean difference demonstrated significant improvements in speech recognition score for words in quiet (37.4%; 95% confidence interval [34.7%, 40.7%]), sentences in quiet (49.4%; 95% confidence interval [44.9%, 53.9%]), and sentences in noise (30.8%; 95% confidence interval [25.2%, 36.4%]) from pre-op to 3 months. Scores continued to increase from 3 to 12 months but did not reach significance. Similarly, significant improvements from pre-op to 3 months were observed for consonant nucleus consonant (CNC) words in quiet (37.1%; 95% confidence interval [33.8%, 40.4%]), hearing in noise test (HINT) sentences in quiet (46.5%; 95% confidence interval [37.0%, 56.0%]), AzBio sentences in quiet (45.9%; 95% confidence interval [44.2%, 47.5%]), and AzBio sentences in noise (26.4%; 95% confidence interval [18.6%, 34.2%]). HINT sentences in noise demonstrated improvement from pre-op to 3 months (35.1%; 95% confidence interval [30.0%, 40.3%]) and from 3 to 12 months (15.5%; 95% confidence interval [7.2%, 23.8%]).

CONCLUSIONS

Mean speech recognition scores demonstrate significant improvement within the first 3 months, with no further statistically significant improvement after 3 months. However, large individual variation should be expected and future research is needed to explain the sources of these individual differences. Laryngoscope, 2022.

Bridging the electrode-neuron gap: finite element modeling of in vitro neurotrophin gradients to optimize neuroelectronic interfaces in the inner ear

Although cochlear implant (CI) technology has allowed for the partial restoration of hearing over the last few decades, persistent challenges (e.g., poor performance in noisy environments and limited ability to decode intonation and music) remain. The "electrode-neuron gap" is inherent to these challenges and poses the most significant obstacle to advancing past the current plateau in CI performance. We propose the development of a "neuro-regenerative nexus"-a biological interface that doubly preserves native spiral ganglion neurons (SGNs) while precisely directing the growth of neurites arising from transplanted human pluripotent stem cell (hPSC)-derived otic neuronal progenitors (ONPs) toward the native SGN population. We hypothesized that the Polyhedrin Delivery System (PODS®-recombinant human brain-derived neurotrophic factor [rhBDNF]) could stably provide the adequate BDNF concentration gradient to hPSC-derived late-stage ONPs to facilitate otic neuronal differentiation and directional neurite outgrowth. To test this hypothesis, a finite element model (FEM) was constructed to simulate BDNF concentration profiles generated by PODS®-rhBDNF based on initial concentration and culture device geometry. For biological validation of the FEM, cell culture experiments assessing survival, differentiation, neurite growth direction, and synaptic connections were conducted using a multi-chamber microfluidic device. We were able to successfully generate the optimal BDNF concentration gradient to enable survival, neuronal differentiation toward SGNs, directed neurite extension of hPSC-derived SGNs, and synaptogenesis between two hPSC-derived SGN populations. This proof-of-concept study provides a step toward the next generation of CI technology. STATEMENT OF SIGNIFICANCE: Our study demonstrates that the generation of in vitro neurotrophin concentration gradients facilitates survival, neuronal differentiation toward auditory neurons, and directed neurite extension of human pluripotent stem cell-derived auditory neurons. These findings are indispensable to designing a bioactive cochlear implant, in which stem cell-derived neurons are integrated into a cochlear implant electrode strip, as the strategy will confer directional neurite growth from the transplanted cells in the inner ear. This study is the first to present the concept of a "neuro-regenerative nexus" congruent with a bioactive cochlear implant to eliminate the electrode-neuron gapthe most significant barrier to next-generation cochlear implant technology.