Neuronal Development of Hearing and Language: Cochlear Implants and Critical Periods.

The modern cochlear implant (CI) is the most successful neural prosthesis developed to date. CIs provide hearing to the profoundly hearing impaired and allow the acquisition of spoken language in children born deaf. Results from studies enabled by the CI have provided new insights into (a) minimal representations at the periphery for speech reception, (b) brain mechanisms for decoding speech presented in quiet and in acoustically adverse conditions, (c) the developmental neuroscience of language and hearing, and (d) the mechanisms and time courses of intramodal and cross-modal plasticity. Additionally, the results have underscored the interconnectedness of brain functions and the importance of top-down processes in perception and learning. The findings are described in this review with emphasis on the developing brain and the acquisition of hearing and spoken language.

Dissociated Representation of Binaural Cues in Single-Sided Deafness: Implications for Cochlear Implantation.

Congenital single-sided deafness (SSD) leads to an aural preference syndrome that is characterized by overrepresentation of the hearing ear in the auditory system. Cochlear implantation (CI) of the deaf ear is an effective treatment for SSD. However, the newly introduced auditory input in congenital SSD often does not reach expectations in late-implanted CI recipients with respect to binaural hearing and speech perception. In a previous study, a reduction of the interaural time difference (ITD) sensitivity has been shown in unilaterally congenitally deaf cats (uCDCs). In the present study, we focused on the interaural level difference (ILD) processing in the primary auditory cortex. The uCDC group was compared with hearing cats (HCs) and bilaterally congenitally deaf cats (CDCs). The ILD representation was reorganized, replacing the preference for the contralateral ear with a preference for the hearing ear, regardless of the cortical hemisphere. In accordance with the previous study, uCDCs were less sensitive to interaural time differences than HCs, resulting in unmodulated ITD responses, thus lacking directional information. Such incongruent ITDs and ILDs cannot be integrated for binaural sound source localization. In normal hearing, the predominant effect of each ear is excitation of the auditory cortex in the contralateral cortical hemisphere and inhibition in the ipsilateral hemisphere. In SSD, however, auditory pathways reorganized such that the hearing ear produced greater excitation in both cortical hemispheres and the deaf ear produced weaker excitation and preserved inhibition in both cortical hemispheres.

A systematic review of altered resting-state networks in early deafness and implications for cochlear implantation outcomes.

Auditory deprivation following congenital/pre-lingual deafness (C/PD) can drastically affect brain development and its functional organisation. This systematic review intends to extend current knowledge of the impact of C/PD and deafness duration on brain resting-state networks (RSNs), review changes in RSNs and spoken language outcomes post-cochlear implant (CI) and draw conclusions for future research. The systematic literature search followed the PRISMA guideline. Two independent reviewers searched four electronic databases using combined keywords: 'auditory deprivation', 'congenital/prelingual deafness', 'resting-state functional connectivity' (RSFC), 'resting-state fMRI' and 'cochlear implant'. Seventeen studies (16 cross-sectional and one longitudinal) met the inclusion criteria. Using the Crowe Critical Appraisal Tool, the publications' quality was rated between 65.0% and 92.5% (mean: 84.10%), ≥80% in 13 out of 17 studies. A few studies were deficient in sampling and/or ethical considerations. According to the findings, early auditory deprivation results in enhanced RSFC between the auditory network and brain networks involved in non-verbal communication, and high levels of spontaneous neural activity in the auditory cortex before CI are evidence of occupied auditory cortical areas with other sensory modalities (cross-modal plasticity) and sub-optimal CI outcomes. Overall, current evidence supports the idea that moreover intramodal and cross-modal plasticity, the entire brain adaptation following auditory deprivation contributes to spoken language development and compensatory behaviours.

Speech-evoked cortical activities and speech recognition in adult cochlear implant listeners: a review of functional near-infrared spectroscopy studies.

Cochlear implants (CIs) are the most successful neural prostheses, enabling individuals with severe to profound hearing loss to access sounds and understand speech. While CI has demonstrated success, speech perception outcomes vary largely among CI listeners, with significantly reduced performance in noise. This review paper summarizes prior findings on speech-evoked cortical activities in adult CI listeners using functional near-infrared spectroscopy (fNIRS) to understand (a) speech-evoked cortical processing in CI listeners compared to normal-hearing (NH) individuals, (b) the relationship between these activities and behavioral speech recognition scores, (c) the extent to which current fNIRS-measured speech-evoked cortical activities in CI listeners account for their differences in speech perception, and (d) challenges in using fNIRS for CI research. Compared to NH listeners, CI listeners had diminished speech-evoked activation in the middle temporal gyrus (MTG) and in the superior temporal gyrus (STG), except one study reporting an opposite pattern for STG. NH listeners exhibited higher inferior frontal gyrus (IFG) activity when listening to CI-simulated speech compared to natural speech. Among CI listeners, higher speech recognition scores correlated with lower speech-evoked activation in the STG, higher activation in the left IFG and left fusiform gyrus, with mixed findings in the MTG. fNIRS shows promise for enhancing our understanding of cortical processing of speech in CI listeners, though findings are mixed. Challenges include test-retest reliability, managing noise, replicating natural conditions, optimizing montage design, and standardizing methods to establish a strong predictive relationship between fNIRS-based cortical activities and speech perception in CI listeners.

Exposure to sign language prior and after cochlear implantation increases language and cognitive skills in deaf children.

Recent evidence suggests that deaf children with CIs exposed to nonnative sign language from hearing parents can attain age-appropriate vocabularies in both sign and spoken language. It remains to be explored whether deaf children with CIs who are exposed to early nonnative sign language, but only up to implantation, also benefit from this input and whether these benefits also extend to memory abilities, which are strongly linked to language development. The present study examined the impact of deaf children's early short-term exposure to nonnative sign input on their spoken language and their phonological memory abilities. Deaf children who had been exposed to nonnative sign input before and after cochlear implantation were compared to deaf children who never had any exposure to sign input as well as to children with typical hearing. The children were between 5;1 and 7;1 years of age at the time of testing and were matched on age, sex, and socioeconomic status. The results suggest that even short-term exposure to nonnative sign input has positive effects on general language and phonological memory abilities as well as on nonverbal working memory-with total length of exposure to sign input being the best predictor of deaf children's performance on these measures. The present data suggest that even access to early short-term nonnative visual language input is beneficial for the language and phonological memory abilities of deaf children with cochlear implants, suggesting also that parents should not be discouraged from learning and exposing their child to sign language. RESEARCH HIGHLIGHTS: This is the first study to examine the effects of early short-term exposure to nonnative sign input on French-speaking children with cochlear implants' spoken language and memory abilities. Early short-term nonnative exposure to sign input can have positive consequences for the language and phonological memory abilities of deaf children with CIs. Extended exposure to sign input has some additional and important benefits, allowing children to perform on par with children with typical hearing.

Impedance and Functional Outcomes in Robotic-Assisted or Manual Cochlear Implantation: A Comparative Study.

INTRODUCTION: Preservation of residual hearing, mainly the low frequencies, is the current main objective of cochlear implantation. New electrode arrays and the development of minimally invasive surgery have allowed electroacoustic stimulation. Over the past several years, robotic-assisted cochlear implant surgery aimed to improve the insertion process while respecting inner ear structures. However, the introduction of a foreign body inside the cochlea can lead to the development of fibrous tissue around the electrode array, or even induce osteogenesis. These histological changes disrupt the parameters of the cochlear implant, resulting in elevated impedance. In addition, long-term auditory performance can be affected, with a deterioration in word comprehension. We evaluated the potential impact of RobOtol® on impedance changes over time, leading to potentially positive functional outcomes. METHODS: Cochlear implant surgery with a round window approach was performed under general anesthesia. Fifteen Med-El Flex24 electrode arrays were inserted manually and 24 using RobOtol®. All subjects underwent pure-tone audiometry tests before the surgery and at regular intervals up to 1 year after the surgery. Based on the pure-tone average at the low frequencies from 250 to 1,000 Hz, we divided the patients according to the degree of auditory preservation (full preservation ≤15 dB, partial preservation 15 dB-30 dB, significant loss >30 dB). These different groups were compared in terms of impedance changes and auditory performance, specifically word recognition score. RESULTS: We found proportionally fewer patients who experienced significant low-frequency hearing loss after robotic insertion (53.33% in the manual group compared to 41.67% in the robot-assisted insertion group). Impedance changes at the apex of the electrode array, especially at the first electrode (p = 0.04), after robotic surgery, with less overall variability, a continuous decreasing trend without secondary elevation, and lower values in cases of complete residual hearing preservation (for the three first electrodes: p = 0.017, p = 0.04, p = 0.045). The speech intelligibility amelioration over time showed favorable evolution in patients with complete residual hearing preservation regardless of the insertion method. However, in the absence of auditory preservation, the positive evolution continued more than 6 months after robotic surgery but stagnated after manual insertion (difference at 1 year, p = 0.038; median auditory capacity index 83% vs. 57%). CONCLUSION: Atraumatic electrode array insertion with consistent, slow speed and the assistance of RobOtol® minimizes disturbances in the delicate neurosensory structures of the inner ear and leads to better auditory performance.

The Benefit of Bimodal Hearing and Beamforming for Cochlear Implant Users.

INTRODUCTION: Cochlear implantation is the standard treatment for severe to profound hearing loss. While cochlear implant (CI) users can communicate effectively in quiet environments, speech understanding in noise remains challenging. Bimodal hearing, combining a CI in one ear and a hearing aid (HA) in the other, has shown advantages over unilateral electrical hearing, especially for speech understanding in noisy conditions. Beamforming is a technique used to improve speech understanding in noise by detecting sound direction and enhancing frontal (speech) sounds while attenuating background noise. One specific beamformer, Stereozoom, combines signals from microphones in both ears to create a focused beam toward the front resulting in a binaural beamformer (BB), in order to improve speech intelligibility in noise for bilateral and bimodal CI users. METHODS: A prospective crossover study involving 17 bimodal CI users was conducted, and participants were tested with various device configurations (CI, HA, CI + HA) with and without BB. Speech recognition testing with the Dutch/Flemish matrix test was performed in a sound-attenuated booth with diffuse noise to simulate realistic listening conditions. RESULTS: The results showed a statistically significant benefit of bimodal hearing over the CI configuration and showed a statistical significant benefit of BB for the CI and CI + HA configuration. The benefit of BB in the HA configuration was not statistically significant probably due to the higher variance. The benefit of BB in the three configurations did not differ statistically significant. CONCLUSION: In conclusion, bimodal hearing offers advantages for speech understanding in noise for CI users. BB provides a benefit in various device configurations, leading to improved speech intelligibility when speech comes from the front in challenging listening environments.

Implantable Hearing Devices in Ontario: A Population-Based Study of Access to Care and Access to Devices.

INTRODUCTION: The prevalence of hearing loss in Canada is high, with many patients requiring implantable hearing devices (IHDs) as treatment for their disease severity. Despite this need, many eligible patients do not pursue these interventions. The objective of this study was to examine rates of IHD based on geographic location to understand locoregional variation in access to care. STUDY DESIGN: This was a retrospective population-based cohort study. SETTING: All hospitals in the Canadian province of Ontario. METHODS: Of all patients with IHD between April 1, 1992, and March 31, 2021, cochlear implants (CIs) (4,720) and bone-anchored hearing aids (BAHA) (1,125) cohorts were constructed. Place of residence was categorized based on Local Health Integrated Network (LHIN). Summary statistics for place of surgical institution based on LHIN at first surgery, name of institution of first surgery and "as the crow flies" distance (in km) between place of residence and surgical institution were calculated. Rate of implantations was calculated for LHIN regions based on number of surgeries per 1,000,000 persons/years. RESULTS: Toronto Central, Central, Central East, and Champlain regions had >10% of patients undergoing BAHA and CI. 1,019 (90.6%) and 4,232 (89.7%) of patients receiving BAHA and CI, respectively, resided in urban/suburban regions and 94 patients (8.4%) and 436 (9.2%) resided in rural regions. The median distance between residential location and the institution was 46.4 km (interquartile range [IQR], 18.9-103.6) and 44.7 km (IQR, 15.7-96.9) for BAHA and CI, respectively. From 1992 to 2021, the number of CI and BAHA performed across Ontario increased by 17 folds and 6 folds, respectively. CONCLUSION: This large comprehensive population study provides longitudinal insight into the access to care of IHD based on geographic factors. Our findings of the present population-based study indicate an overall increase in access to devices with disproportionate access to care based on geographic locations. Further work is needed to characterize barriers to IHD access to align with demands.

The (in)visibility of deafness: Identity, stigma, quality of life and the potential role of totally implantable cochlear implants.

INTRODUCTION: The disclosure of deafness is complex, given the historic and on-going stigma associated with being deaf. The aim of this study was to explore how identity, stigma, and quality of life may be impacted when using cochlear implants (CIs) and totally implantable cochlear implants (TICIs). The physical difference between these two assistive listening devices is significant, given many CI users opt to hide their sound processor behind hair or headwear, in contrast to TICIs (an emerging technology) whereby all components are implanted internally and thus invisible. METHODS: This qualitative study involved semistructured interviews and demographic questionnaires with 12 adult participants with more than 1 year of experience using their CI. Participants were recruited Australia-wide through community organisations that support deaf and hard-of-hearing individuals. Interview transcripts were analysed thematically, with the themes generated through an inductive process, with consensus generated through group working with three members from the research team. RESULTS: Four major themes were identified: (1) CI challenges; (2) The importance of social and support networks; (3) Identity and disclosure and (4) Concerns about TICIs. The underlying finding was centred around the construction of deaf identity. Participant attitudes were generally categorised as 'Loud and proud', with the recognition that displaying the CI was an extension of self, something to be proud of, and a means to normalise deafness; or 'Out of sight and out of mind', which sought to minimise the visibility of deafness. While both identities differed in how deafness is disclosed, they are fundamentally related to the same ideas of self-agency and empowerment. CONCLUSION: TICIs present a novel opportunity-the ability for CI users to control the visibility of their deafness and thus control disclosure. This study explored the impact of stigma and categorised two core identities that CI users construct. Future directions include investigating potential CI candidates, to explore if TICIs may be a facilitator to CI uptake. PATIENT OR PUBLIC CONTRIBUTION: The semistructured interview guide was developed in consultation with adults with CIs. Feedback led to adjustments and improvement to the interview guide. In addition, F. R. has a lived experience with hearing loss, and C. Y. L. is an executive committee member for a nonprofit charity organisation that supports families that are D/deaf and hard-of-hearing.

Patient-Led Research to Develop a Training Programme for Restoring Musical Joy in Cochlear Implant Recipients: A Reflexive Process Evaluation.

BACKGROUND: The role of patients in healthcare research is slowly evolving, although patient roles in the research process are limited. This paper reports on a patient-led research project aiming to develop a musical hearing training programme for patients with a cochlear implant (CI): the Musi-CI programme. A CI is an inner ear prosthesis that allows people with severe hearing loss to hear. However, while speech can be understood, CI users cannot fully enjoy music or feel aversion to it. The Musi-CI programme aims to reduce this music aversion to ultimately improve music enjoyment and social participation. The development of the Musi-CI programme was supported by a consortium of professionals in CI rehabilitation and research. The aim of this paper is to describe and evaluate the Musi-CI programme development process and its impact on professional CI rehabilitation and research. METHODS: Programme development was described using a 3-layered process model of action research, distinguishing the CI user process, the healthcare professional process and the research process. To evaluate perceptions on the programme development process, consortium partners provided written comments and participated in a reflexive evaluation session that was video-recorded. Reflexive evaluation aims for collective learning and strengthening collaboration among participants. Written comments and video data were analysed using template analysis. RESULTS: The involvement of an expert by experience was perceived as challenging but rewarding for all consortium partners, opening up new perspectives on CI-rehabilitation practice and research. Data analysis revealed two themes on the programme development process, professional space and acknowledgement, and two themes on the outcomes on CI rehabilitation and research: critical reflection and paradigm shift. CONCLUSION: Experts by experience represent a different knowledge domain that may contribute to change in rehabilitation and research. PATIENT OR PUBLIC CONTRIBUTION: The development of the programme was initiated by a professional musician and CI user who organized the funding, had a leading role throughout the research process, including the write-up of the results, and co-authored this paper.

Differences in music appreciation between bilateral and single-sided cochlear implant recipients.

OBJECTIVE: To compare changes in music appreciation after cochlear implant (CI) surgery for patients with bilateral and single-sided deafness (SSD). METHODS: A retrospective cohort study was performed on all adult CI unilateral or bilateral recipients from November 2019 to March 2023. Musical questionnaire subset data from the Cochlear Implant Quality of Life (CIQOL) - 35 Profile Instrument Score (maximum raw score of 15) was collected. Functional CI assessment was measured with CI-alone speech-in-quiet (SIQ) scores (AzBio and CNC). RESULTS: 22 adults underwent CI surgery for SSD and 21 adults for bilateral deafness (8 sequentially implanted). Every patient group had clinically significant improvements (p < 0.001) in mean SIQ scores in the most recently implanted ear (Azbio (% correct) SSD: 14.23 to 68.48, bilateral: 24.54 to 82.23, sequential: 6.25 to 82.57). SSD adults on average had higher music QOL scores at baseline (SSD: 11.05; bilateral: 7.86, p < 0.001). No group had significant increases in raw score at the first post-operative visit (SSD: 11.45, p = 0.86; bilateral: 8.15, p = 0.15). By the most recent post-implantation evaluation (median 12.8 months for SSD, 12.3 months for bilateral), SSD adults had a significant increase in raw score from baseline (11.05 to 12.45, p = 0.03), whereas bilaterally deafened (7.86 to 9.38, p = 0.12) adults had nonsignificant increases. CONCLUSIONS: SSD patients demonstrate higher baseline music appreciation than bilaterally deafened individuals regardless of unilateral or bilateral implantation and are more likely to demonstrate continued improvement in subjective music appreciation at last follow-up even when speech perception outcomes are similar.

Hearing outcomes following reimplantation of functional legacy cochlear implants.

OBJECTIVES: Recently, patients with certain legacy cochlear implants (CIs) have sought out reimplantation to enjoy the benefits offered by newer processor technology. This decision can be difficult, especially when the individual relies exclusively on the device for communication and scores at the ceiling of performance metrics. To date, most outcome data is derived from reimplantation of a non-functioning CI-a relatively easy decision. The aim of this study is to report hearing outcomes following reimplantation of legacy implants to guide surgeons and patients approaching this high-stakes clinical situation. PATIENTS AND INTERVENTION: Four patients implanted with Advanced Bionics Clarion C1 devices over 20 years ago underwent reimplantation. RESULTS: Three reimplanted patients demonstrated a maintenance or improvement in their audiometric performance with one patient experiencing only a 5 % decrease in AzBioQ score. Each patient expressed satisfaction with the expansion of technological capabilities including improved battery life, and device connectivity. There were no failed reimplantations or other adverse effects. CONCLUSIONS: Reimplantation of a functioning legacy CI result in stability or improvement in auditory performance. All individuals in this series report that they enjoy the new connectivity and programming technologies. As the rate advancement in CI technology continues to increase and newer device architectures emerge, these data will help to inform the decision to reimplant functioning devices.

"Repository of Cochlear Implant Information:" A Multi-Institutional REDCap Database.

PURPOSE: To describe the creation of a multi-center cochlear implant database as a template for future medical database design. The first clinical question examined was the association between BMI on cochlear implant surgical time and postoperative outcome. MATERIALS AND METHODS: A retrospective repository in REDCap, named the "Repository of Cochlear Implant Information" (ROCII), was created and collected de-identified data on patients who underwent cochlear implantation. Data was exported and stratified into three BMI groupings (<25, 25.0-29.9, ≥ 30.0). Differences in surgical time and AZBio Sentence Test postoperative score changes were analyzed using the mixed-effect model. RESULTS: The mean BMI (n = 145) was 28.52, and the mean surgical time was 128.9 min. The BMI < 25 reference group (n = 50) and the BMI 25.0-29.9 group (n = 50) had an identical mean surgical time of 127.5 min. The BMI ≥30.0 group (n = 45) had a mean surgical time of 132 min, however this difference was not statistically significant when compared to the reference group (p = 0.4727). The mean AZBio postoperative score change (n = 74) was 63.32. The BMI < 25 reference group (n = 29) had a mean postoperative change of 56.66. The BMI 25.0-29.9 group (n = 22) and BMI ≥30.0 group (n = 23) had mean postoperative changes of 61.32 and 73.65 respectively, however these differences were not statistically significant compared to the reference group (p = 0.5847, 0.0637). CONCLUSION: BMI did not have a significant association with surgical time or postoperative outcome and therefore should not be a contraindication for implantation. ROCII will facilitate a deeper understanding of the evaluation process, outcomes, and patient experience of cochlear implantation across institutions. LEVEL OF EVIDENCE: Level 1.

Patient and clinician experiences with the multidisciplinary single-day cochlear implant selection (MSCS) protocol.

PURPOSE: This study assessed the MSCS (Multidisciplinary Single-day Cochlear Implant Selection) protocol with a primary focus on sustaining or enhancing patient satisfaction throughout the cochlear implant selection process. MATERIALS AND METHODS: Following the implementation of the new selection protocol, where all selection appointments take place on the same day, we surveyed 37 individuals who underwent the process. Twenty adhered to the standard procedure, while 17 followed the MSCS protocol. We also gathered feedback from seven out of eight involved healthcare providers. This method enabled us to evaluate the protocol's effectiveness in maintaining patient satisfaction and ensuring staff contentment with care delivery within a condensed timeframe. RESULTS: Patient responses showed slight variations in average scores without statistical significant differences, indicating comparable satisfaction between the MSCS pathway and the standard protocol. The majority of patients preferred the MSCS protocol, with none of the MSCS participants opting for appointments spread over multiple days. Healthcare practitioners of the CI center also displayed similar or increased satisfaction levels with the MSCS protocol. CONCLUSION: The adoption of the MSCS in daily clinical care has led to a decrease in patient appointment times without sacrificing patient satisfaction. Additionally, the majority of individuals actively choose the MSCS protocol. Among those who have directly experienced it, there is unanimous preference for the consolidated appointments over spreading them across multiple days. Professionals within the CI team express equal satisfaction with both the new and old protocols, indicating that the reduction in patient time does not diminish overall satisfaction.

Pilot study of a multidisciplinary single-day cochlear implant selection protocol.

PURPOSE: This study aimed to explore and introduce the potential of a MSCS (Multidisciplinary Single-day Cochlear Implant Selection) protocol. The primary objectives of this pilot were to reduce the duration between referral and surgery, minimize hospital visits and decrease the time healthcare professionals dedicate to the cochlear implant (CI) selection process. MATERIALS AND METHODS: We established a pilot program at the CI center of the Erasmus MC, a tertiary referral center in the Netherlands, with the goal of improving and shorten the selection process. We evaluated our pilot, including 15 CI candidates, and conducted a retrospective analysis for time and cost savings. RESULTS: The results showed that the pilot of the MSCS protocol significantly reduced the length of the CI selection phase (84 days vs 1; standard intake vs MSCS protocol) and the number of hospital visits (6 vs 2 visits; standard vs MSCS protocol), resulting in less travel time and lower costs for the CI candidates. The total time of professionals spend on patients was also reduced with 27 %. CONCLUSION: This study highlights the potential benefits of the MSCS protocol in terms of reducing the burden on patients and healthcare providers and improving the efficiency of the CI selection process.

Patients with Mondini deformty: is standard electrode necessary?

PURPOSE: The aim of this study is to compare the results of auditory perception tests and speech sound evaluations with electrode array length in patients with Mondini deformity. METHODS: The study included 14 patients who underwent cochlear implantation and radiologically confirmed Mondini deformity between 2007 and 2021 in our clinic. While 7 patients received standard electrode arrays from the MED-EL brand, the remaining 7 received shortened electrode arrays from the MED-EL brand. Differences in auditory perception, articulation, and speech intelligibility between the two groups were examined. Auditory perception tests were administered to these patients preoperatively and at least 2 years after cochlear implant surgery. The patients' auditory perception performance was evaluated using single, double, and triple closed-set word tests (MTP-3, MTP-6, MTP-12), two-syllable open-set word test, Glendonald Auditory Screening Procedure (GASP) tests for articulation, Phonemic Synthesis Test (SST) for phonemic knowledge, and Speech Intelligibility Rating (SIR) test for speech intelligibility. RESULTS: Both groups did not show statistically significant differences in auditory perception tests (MTP-3, MTP-6, MTP-12, two-syllable open-set word test), speech sound tests (SST), and speech intelligibility test (SIR). Significant improvement was observed in all tests in both groups when compared preoperatively and postoperatively. CONCLUSION: No significant difference was observed in auditory perception and speech sound tests between groups with short and standard electrode arrays in patients with Mondini deformity. The option of using short electrode arrays during implantation in patients with Mondini deformity can be preferred without doubt in terms of outcomes.

The relation between cochlear implant programming levels and speech perception performance in post-lingually deafened adults: a data-driven approach.

PURPOSE: Programming a cochlear implant (fitting) is an essential part of a user's post-implantation journey, defining how sound will be translated into electrical stimulation and aiming to provide optimal speech perception outcomes. Currently, there are no established, evidence-based guidelines for fitting cochlear implant users, leading to a high degree of variability in fitting practices, users' parameters, and probably outcomes. In this study a data-driven approach is used to retrospectively investigate the relation between cochlear implant fitting parameters and speech perception outcomes in post-lingually deafened adults. METHODS: 298 data points corresponding to fitting parameters and speech audiometry test results for the same number of adult, post-lingually deafened, experienced CI users were analyzed. Correlation analysis was performed, after which parameters from the top-scoring and bottom-scoring tertiles were compared via the Mann-Whitney-Wilcoxon u test. RESULTS: Weak correlations between dynamic range and speech audiometry outcomes were identified, having p values lower than (albeit close to) 0.05. A significant (p < 0.05) difference in electrical dynamic range (the difference between the minimum and maximum amount of current which may be delivered by each electrode) was found, with top-scoring subjects having on average a wider dynamic range. CONCLUSION: The association between dynamic range and speech perception outcomes shown in this retrospective study highlights the need for deeper investigation into evidence-driven fitting. It might be a first step in the direction of evidence-based fitting, minimizing variability in outcomes for cochlear implant users and helping mitigate the issue of unexplained low performance.

Auditory performance and language skills in children with auditory brainstem implants and cochlear implants.

PURPOSE: This study aims to evaluate school-age language skills and auditory performance in different listening situations in children with cochlear implants and auditory brainstem implants. METHOD: The study included 60 children between the ages of 5 and 9 years with cochlear implants (CI) and auditory brainstem implants (ABI). The volunteer children were divided into two groups: bimodal CI-ABI and bilateral CI users. Test of Language Development: Primary (TOLD-P:4), which assesses components of language such as phonology, morphology, syntax and semantics, was used to evaluate school-age language skills. Children's Auditory Performance Scale (CHAPS) was used to measure their listening performance in quiet, noisy, multi-stimulus environments and their auditory attention and memory skills in daily life. The correlations between language and auditory performance were analyzed and compared between the two groups. RESULTS: Children with ABI showed poorer performance in school-age language skills and auditory performance in different listening environments (p < 0.05). Significant correlations were between school-age language skills and auditory performance (p < 0.05). CONCLUSION: Improved auditory performance is crucial for the development of school-age language skills. To improve auditory performance in children with ABI in different listening environments, assistive listening devices, acoustic environmental arrangements, informative activities, etc., should be used.

Bilateral cochlear implants in a MELAS patient.

BACKGROUND: Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a maternally inherited mitochondrial disease that affects various systems in the body, particularly the brain, nervous system, and muscles. Among these systems, sensorineural hearing loss is a common additional symptom. METHODS: A 42-year-old female patient with MELAS who experienced bilateral profound deafness and underwent bilateral sequential cochlear implantation (CIs). Speech recognition and subjective outcomes were evaluated. RESULTS: Following the first CI follow-up, the patient exhibited improved speech recognition ability and decided to undergo the implantation of the second ear just two months after the initial CI surgery. The second CI also demonstrated enhanced speech recognition ability. Subjective outcomes were satisfactory for bilateral CIs. CONCLUSIONS: MELAS patients receiving bilateral CIs can attain satisfactory post-CI speech recognition, spatial hearing, and sound qualities.

Is the spread of excitation different between adults and children cochlear implants users?

PURPOSE: While cochlea is adult size at birth, etiologies and bone density may differ between children and adults. Differences in neural response thresholds (tNRT) and the spread of excitation (SOE) width may impact the use of artificial intelligence algorithms in speech processor fitting. AIM: To identify whether neural response telemetry threshold and spread of excitation width are similar in adults and children. METHODS: Retrospective cross-sectional study approved by the Ethical Board. Intraoperative tNRT and SOE recordings of consecutive cochlear implant surgeries in adults and children implanted with Cochlear devices (Cochlear™, Australia) were selected. SOE was recorded on electrode 11 (or adjacent, corresponding to the medial region of the cochlea) through the standard forward-masking technique in Custom Sound EP software, which provides SOE width in millimeters. Statistical comparison between adults and children was performed using the Mann-Whitney test (p ≤ 0.05). RESULTS: Of 1282 recordings of intraoperative evaluations, 414 measurements were selected from children and adults. Despite the tNRT being similar between adults and children, SOE width was significantly different, with lower values in children with perimodiolar arrays. Besides, it was observed that there is a difference in the electrode where the SOE function peak occurred, more frequently shifted to electrode 12 in adults implanted. In straight arrays, there was no difference in any of the parameters analyzed on electrode 11. CONCLUSION: Although eCAP thresholds are similar, SOE measurements differ between adults and children in perimodiolar electrodes.