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.

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.

Development of an Algorithm for Correct Placement of the Basal Electrode Contact in the Context of Anatomy-Based Cochlear Implantation: A Proof of Concept.

BACKGROUND: Correct individual tonotopic frequency stimulation of the cochlea plays an important role in the further development of anatomy-based cochlear implantation. In this context, frequency-specific fitting of the basal electrode contact with a normal insertion depth can be difficult since it is often placed in a frequency range higher than 10 kHz, and current audio processors only stimulate for frequencies up to 8.5 kHz due to microphone characteristics. This results in a mismatch of the high frequencies. Therefore, this study represents a proof of concept for a tonotopic correct insertion and aims to develop an algorithm for a placement of the basal electrode below 8.5 kHz in an experimental setting. METHODS: Pre- and postoperative flat-panel volume CT scans with secondary reconstructions were performed on 10 human temporal bone specimens. The desired frequency location for the most basal electrode contact was set at 8.25 kHz. The distance from the round window to the position where the basal electrode contact was intended to be located was calculated preoperatively using 3D-curved multiplanar reconstruction and a newly developed mathematical approach. A specially designed cochlear implant electrode array with customized markers imprinted on the silicone of the electrode array was inserted in all specimens based on the individually calculated insertion depths. All postoperative measurements were additionally validated using otological planning software. RESULTS: Positioning of the basal electrode contact was reached with only a small mean deviation of 37 ± 399 Hz and 0.06 ± 0.37 mm from the planned frequency of 8.25 kHz. The mean rotation angle up to the basal electrode contact was 51 ± 5°. In addition, the inserted electrode array adequately covered the apical regions of the cochleae. CONCLUSION: Using this algorithm, it was possible to position the basal electrode array contact in an area of the cochlea that could be correctly stimulated by the existing speech processors in the context of tonotopic correct fitting.

Cochlear Implant: Analysis of the Frequency-to-Place Mismatch with the Table-Based Software OTOPLAN® and Its Influence on Hearing Performance.

OBJECTIVE: The purpose of this study was to compare the originally applied frequency allocation of cochlear implant electrodes assigned by default at the time of activation with a more recent frequency allocation that is anatomy-based by a software called OTOPLAN®. Based on a computed tomography scan of the temporal bone, this software calculates the position of each electrode in the cochlea and its corresponding tonotopic frequency. We also evaluated whether patients with a significant mismatch between these two allocations present poorer speech intelligibility. MATERIALS AND METHODS: Patients who underwent cochlear implantation from 2016 to 2021 at the University Hospital of Liege were included in this retrospective study. We used OTOPLAN® to calculate the tonotopic frequency allocation of each electrode according to its exact position in the cochlear duct. This anatomical frequency mapping was compared with the default frequency mapping at the time of cochlear implant activation. Finally, we compared the mismatch with the patients' auditory performance, represented by the Auditory Capacity Index (ACI). RESULTS: Thirteen patients were included in the study. All patients had a mismatch between the two frequency maps, to a variable extent (200 Hz-1,100 Hz). Frequency shift was significantly inversely correlated with ACI and with the time needed to improve speech intelligibility. CONCLUSION: Our primary results show that patients with a larger mismatch between default frequency mapping and anatomically assigned frequency mapping experience poorer hearing performance and slower adaptation to a cochlear implant.

Analysis of Cochlear Morphology for Cochlear Implantation Using Three-Dimensional Reconstruction of Computed Tomography Images.

INTRODUCTION: Preoperative evaluation of cochlear morphology is important for successful cochlear implantation. This study analyzed the cochlear canal by three-dimensional reconstructions of temporal bones using computed tomography (CT). METHODS: Fifty temporal bones from 25 patients aged 42-74 years were evaluated. The inner spaces of the bony cochlea were reconstructed using a surface rendering technique on the CT images. Eight angular points (P0-P7) every 90° were selected from 0° to 630° from the center of the round window using the reconstructed cochlear canal images. The radius (R) and thickness (T) of the cochlear canal at each point were measured. The cochlear canal length (CoCL) was estimated using an equation based on the radius at each point. The cochlear width and height based on multiplanar CT images were also measured and compared with the length and volume of the cochlear canal. RESULTS: The mean CoCL from 0° to 630° was 31.5 mm, and the cochlear volume was 55.9 mm3. The CoCL to P7 was correlated with the cochlear volume (r = 0.77), coiling ratios (R4/R0, r = 0.47; R5/R1, r = 0.384), cochlear width (long) (r = 0.539), cochlear height (r = 0.385), and total thickness at each point (r = 0.475). The cochlear volume was correlated with CoCL (630°) (r = 0.77), coiling ratio (R4/R0, r = 0.367), cochlear width (long) (r = 0.616), cochlear height (r = 0.447), and total T (r = 0.566). CONCLUSION: Preoperative evaluation using three-dimensional reconstruction can elucidate the size and shape of the cochlear canal before cochlear implantation.

Comparison of Tonotopic and Default Frequency Fitting for Speech Understanding in Noise in New Cochlear Implantees: A Prospective, Randomized, Double-Blind, Cross-Over Study.

OBJECTIVES: While cochlear implants (CIs) have provided benefits for speech recognition in quiet for subjects with severe-to-profound hearing loss, speech recognition in noise remains challenging. A body of evidence suggests that reducing frequency-to-place mismatch may positively affect speech perception. Thus, a fitting method based on a tonotopic map may improve speech perception results in quiet and noise. The aim of our study was to assess the impact of a tonotopic map on speech perception in noise and quiet in new CI users. DESIGN: A prospective, randomized, double-blind, two-period cross-over study in 26 new CI users was performed over a 6-month period. New CI users older than 18 years with bilateral severe-to-profound sensorineural hearing loss or complete hearing loss for less than 5 years were selected in the University Hospital Centre of Rennes in France. An anatomical tonotopic map was created using postoperative flat-panel computed tomography and a reconstruction software based on the Greenwood function. Each participant was randomized to receive a conventional map followed by a tonotopic map or vice versa. Each setting was maintained for 6 weeks, at the end of which participants performed speech perception tasks. The primary outcome measure was speech recognition in noise. Participants were allocated to sequences by block randomization of size two with a ratio 1:1 (CONSORT Guidelines). Participants and those assessing the outcomes were blinded to the intervention. RESULTS: Thirteen participants were randomized to each sequence. Two of the 26 participants recruited (one in each sequence) had to be excluded due to the COVID-19 pandemic. Twenty-four participants were analyzed. Speech recognition in noise was significantly better with the tonotopic fitting at all signal-to-noise ratio (SNR) levels tested [SNR = +9 dB, p = 0.002, mean effect (ME) = 12.1%, 95% confidence interval (95% CI) = 4.9 to 19.2, standardized effect size (SES) = 0.71; SNR = +6 dB, p < 0.001, ME = 16.3%, 95% CI = 9.8 to 22.7, SES = 1.07; SNR = +3 dB, p < 0.001 ME = 13.8%, 95% CI = 6.9 to 20.6, SES = 0.84; SNR = 0 dB, p = 0.003, ME = 10.8%, 95% CI = 4.1 to 17.6, SES = 0.68]. Neither period nor interaction effects were observed for any signal level. Speech recognition in quiet ( p = 0.66) and tonal audiometry ( p = 0.203) did not significantly differ between the two settings. 92% of the participants kept the tonotopy-based map after the study period. No correlation was found between speech-in-noise perception and age, duration of hearing deprivation, angular insertion depth, or position or width of the frequency filters allocated to the electrodes. CONCLUSION: For new CI users, tonotopic fitting appears to be more efficient than the default frequency fitting because it allows for better speech recognition in noise without compromising understanding in quiet.

Effect of Return Electrode Placement at Apical Cochleostomy on Current Flow With a Cochlear Implant.

OBJECTIVES: A method for stimulating the cochlear apex using perimodiolar electrode arrays is described. This method involves implanting an electrode (ECE1) into the helioctrema in addition to standard cochlear implant placement. One objective is to verify a suitable approach for implanting ECE1 in the helicotrema. Another is to determine how placement of ECE1 reshapes electric fields. DESIGN: Two cadaveric half-heads were implanted, and electric voltage tomography was measured with ECE1 placed in many positions. RESULTS: An approach for placing ECE1 was identified. Changes in electric fields were only observed when ECE1 was placed into the fluid in the helicotrema. When inside the helicotrema, electric voltage tomography modeling suggests an increased current flow toward the apex. CONCLUSIONS: Placement of ECE1 into the cochlear apex is clinically feasible and has the potential to reshape electric fields to stimulate regions of the cochlea more apical than those represented by the electrode array.

A Guinea Pig Model Suggests That Objective Assessment of Acoustic Hearing Preservation in Human Ears With Cochlear Implants Is Confounded by Shifts in the Spatial Origin of Acoustically Evoked Potential Measurements Along the Cochlear Length.

OBJECTIVES: Our recent empirical findings have shown that the auditory nerve compound action potential (CAP) evoked by a low-level tone burst originates from a narrow cochlear region tuned to the tone burst frequency. At moderate to high sound levels, the origins shift to the most sensitive audiometric regions rather than the extended high-frequency regions of the cochlear base. This means that measurements evoked from extended high-frequency sound stimuli can shift toward the apex with increasing level. Here we translate this study to understand the spatial origin of acoustically evoked responses from ears that receive cochlear implants, an emerging area of research and clinical practice that is not completely understood. An essential step is to first understand the influence of the cochlear implant in otherwise naive ears. Our objective was to understand how function of the high-frequency cochlear base, which can be excited by the intense low-frequency sounds that are frequently used for objective intra- and postoperative monitoring, can be influenced by the presence of the cochlear implant. DESIGN: We acoustically evoked responses and made measurements with an electrode placed near the guinea pig round window. The cochlear implant was not utilized for either electrical stimulation or recording purposes. With the cochlear implant in situ, CAPs were acoustically evoked from 2 to 16 kHz tone bursts of various levels while utilizing the slow perfusion of a kainic acid solution from the cochlear apex to the cochlear aqueduct in the base, which sequentially reduced neural responses from finely spaced cochlear frequency regions. This cochlear perfusion technique reveals the spatial origin of evoked potential measurements and provides insight on what influence the presence of an implant has on acoustical hearing. RESULTS: Threshold measurements at 3 to 11 kHz were elevated by implantation. In an individual ear, thresholds were elevated and lowered as cochlear implant was respectively inserted and removed, indicative of "conductive hearing loss" induced by the implant. The maximum threshold elevation occurred at most sensitive region of the naive guinea pig ear (33.66 dB at 8 kHz), making 11 kHz the most sensitive region to acoustic sounds for guinea pig ears with cochlear implants. Conversely, the acute implantation did not affect the low-frequency, 500 Hz thresholds and suprathreshold function, as shown by the auditory nerve overlapped waveform. As the sound pressure level of the tone bursts increased, mean data show that the spatial origin of CAPs along the cochlear length shifted toward the most sensitive cochlear region of implanted ears, not the extended high-frequency cochlear regions. However, data from individual ears showed that after implantation, measurements from moderate to high sound pressure levels originate in places that are unique to each ear. CONCLUSIONS: Alterations to function of the cochlear base from the in situ cochlear implant may influence objective measurements of implanted ears that are frequently made with intense low-frequency sound stimuli. Our results from guinea pigs advance the interpretation of measurements used to understand how and when residual acoustic hearing is lost in human ears receiving a cochlear implant.

Electrocochleography-Based Tonotopic Map: II. Frequency-to-Place Mismatch Impacts Speech-Perception Outcomes in Cochlear Implant Recipients.

OBJECTIVES: Modern cochlear implants (CIs) use varying-length electrode arrays inserted at varying insertion angles within variably sized cochleae. Thus, there exists an opportunity to enhance CI performance, particularly in postlinguistic adults, by optimizing the frequency-to-place allocation for electrical stimulation, thereby minimizing the need for central adaptation and plasticity. There has been interest in applying Greenwood or Stakhovskaya et al. function (describing the tonotopic map) to postoperative imaging of electrodes to improve frequency allocation and place coding. Acoustically-evoked electrocochleography (ECochG) allows for electrophysiologic best-frequency (BF) determination of CI electrodes and the potential for creating a personalized frequency allocation function. The objective of this study was to investigate the correlation between early speech-perception performance and frequency-to-place mismatch. DESIGN: This retrospective study included 50 patients who received a slim perimodiolar electrode array. Following electrode insertion, five acoustic pure-tone stimuli ranging from 0.25 to 2 kHz were presented, and electrophysiological measurements were collected across all 22 electrode contacts. Cochlear microphonic tuning curves were subsequently generated for each stimulus frequency to ascertain the BF electrode or the location corresponding to the maximum response amplitude. Subsequently, we calculated the difference between the stimulus frequency and the patient's CI map's actual frequency allocation at each BF electrode, reflecting the frequency-to-place mismatch. BF electrocochleography-total response (BF-ECochG-TR), a measure of cochlear health, was also evaluated for each subject to control for the known impact of this measure on performance. RESULTS: Our findings showed a moderate correlation ( r = 0.51; 95% confidence interval: 0.23 to 0.76) between the cumulative frequency-to-place mismatch, as determined using the ECochG-derived BF map (utilizing 500, 1000, and 2000 Hz), and 3-month performance on consonant-nucleus-consonant words (N = 38). Larger positive mismatches, shifted basal from the BF map, led to enhanced speech perception. Incorporating BF-ECochG-TR, total mismatch, and their interaction in a multivariate model explained 62% of the variance in consonant-nucleus-consonant word scores at 3 months. BF-ECochG-TR as a standalone predictor tended to overestimate performance for subjects with larger negative total mismatches and underestimated the performance for those with larger positive total mismatches. Neither cochlear diameter, number of cochlear turns, nor apical insertion angle accounted for the variability in total mismatch. CONCLUSIONS: Comparison of ECochG-BF derived tonotopic electrode maps to the frequency allocation tables reveals substantial mismatch, explaining 26.0% of the variability in CI performance in quiet. Closer examination of the mismatch shows that basally shifted maps at high frequencies demonstrate superior performance at 3 months compared with those with apically shifted maps (toward Greenwood and Stakhovskaya et al.). The implications of these results suggest that electrophysiological-based frequency reallocation might lead to enhanced speech-perception performance, especially when compared with conventional manufacturer maps or anatomic-based mapping strategies. Future research, exploring the prospective use of ECochG-based mapping techniques for frequency allocation is underway.

Long-Term Outcome of Cochlear Implantation in Children With Congenital, Perilingual, and Postlingual Single-Sided Deafness.

OBJECTIVES: We investigated the long-term outcomes of children with single-sided deafness (SSD) after cochlear implant (CI) surgery, during and after rehabilitation, and compared the results of children with congenital, perilingual, and postlingual SSD. We evaluated the impact of SSD at age at onset and duration of deafness on their performance. DESIGN: Thirty-six children with SSD treated with CI participated in the study: 20 had congenital, seven perilingual (defined: >0 to 4 years), and nine had postlingual deafness (defined as >4 years of age). Their outcome with CI were measured on both subjective and objective scales: duration of device use, speech intelligibility in noise and in quiet, bilateral hearing and localization ability, quality of life and hearing, presence and loudness of tinnitus, and hearing ability of the better hearing ear. RESULTS: After a mean follow-up time of 4.75 years, 32 of the 36 children used their CI on a regular basis. The remaining four children were nonusers. These children had congenital SSD and were older than three years at the time of CI surgery. Overall, for congenital/perilingual and postlingual SSD, speech intelligibility in noise and the Speech, Spatial and Qualities of Hearing Scale (SSQ) speech subscore were significantly improved, as were their subjective and objective localization ability and hearing-related quality of life. Children with postlingual SSD benefited from the CI with regard to speech intelligibility, SSQ speech/spatial/total score, and localization error, and children with congenital SSD showed better results with a short duration of deafness of less than 3 years compared with those with a longer deafness period. CONCLUSIONS: Cochlear implantation is a successful treatment for children with congenital/perilingual or postlingual SSD. Results largely differed with respect to the onset and duration of deafness, and better outcomes were achieved by children with postlingual SSD and with a short duration of deafness. Our data also confirmed that children with congenital SSD should be implanted with a CI within three years of age.

Auditory cortical plasticity after cochlear implantation in asymmetric hearing loss is related to spatial hearing: a PET H215O study.

In asymmetric hearing loss (AHL), the normal pattern of contralateral hemispheric dominance for monaural stimulation is modified, with a shift towards the hemisphere ipsilateral to the better ear. The extent of this shift has been shown to relate to sound localization deficits. In this study, we examined whether cochlear implantation to treat postlingual AHL can restore the normal functional pattern of auditory cortical activity and whether this relates to improved sound localization. The auditory cortical activity was found to be lower in the AHL cochlear implanted (AHL-CI) participants. A cortical asymmetry index was calculated and showed that a normal contralateral dominance was restored in the AHL-CI patients for the nonimplanted ear, but not for the ear with the cochlear implant. It was found that the contralateral dominance for the nonimplanted ear strongly correlated with sound localization performance (rho = 0.8, P < 0.05). We conclude that the reorganization of binaural mechanisms in AHL-CI subjects reverses the abnormal lateralization pattern induced by the deafness, and that this leads to improved spatial hearing. Our results suggest that cochlear implantation enables the reconstruction of the cortical mechanisms of spatial selectivity needed for sound localization.

Comparison of 96-kV and 120-kV cone-beam CT for the assessment of cochlear implants.

BACKGROUND: To compare the diagnostic value of 120-kV with conventional 96-kV Cone-Beam CT (CBCT) of the temporal bone after cochlear implant (CI) surgery. METHODS: This retrospective study included CBCT scans after CI surgery between 06/17 and 01/18. CBCT allowed examinations with 96-kV or 120-kV; other parameters were the same. Two radiologists independently evaluated following criteria on 5-point Likert scales: osseous spiral lamina, inner and outer cochlear wall, semi-circular canals, mastoid trabecular structure, overall image quality, metal and motion artefacts, depiction of intracochlear electrode position and visualisation of single electrode contacts. Effective radiation dose was assessed. RESULTS: Seventy-five patients (females, n = 39 [52.0%], mean age, 55.8 ± 16.5 years) were scanned with 96-kV (n = 32, 42.7%) and 120-kV (n = 43, 57.3%) protocols including CI models from three vendors (vendor A n = 7; vendor B n = 43; vendor C n = 25). Overall image quality, depiction of anatomical structures, and electrode position were rated significantly better in 120-kV images compared to 96-kV (all p < = 0.018). Anatomical structures and electrode position were rated significantly better in 120-kV CBCT for CI models from vendor A and C, while 120-kV did not provide improved image quality in CI models from vendor B. Radiation doses were significantly higher for 120-kV scans compared to 96-kV (0.15 vs. 0.08 mSv, p < 0.001). CONCLUSIONS: 120-kV and 96-kV CBCT provide good diagnostic images for the postoperative CI evaluation. While 120-kV showed improved depiction of temporal bone and CI electrode position compared to 96-kV in most CI models, the 120-kV protocol should be chosen wisely due to a substantially higher radiation exposure.

Bilateral simultaneous cochlear implants in children: Best timing of surgery and long-term auditory outcomes.

PURPOSE: Evaluate the hearing outcomes of bilateral deaf children implanted simultaneously and define the most appropriate timing for surgery. MATERIALS AND METHODS: Audiological CI results were retrieved in both the short-term and long-term period and compared by stratifying the patients into different subcohorts according to their age at surgery. Additional data collected were age at implant activation, etiology and timing of onset of deafness, presence of psychomotor delay. RESULTS: fifty-six bilaterally implanted children were included. The short-term outcomes differed significantly when comparing groups of different ages at implantation: younger patients achieved better aided pure tone audiometry results. Considering long-term follow-up, a significant correlation was identified between an early age at implantation and the hearing outcome at ages 2 to 5 years. Perceptive levels were better at 4 years of age in the younger group. No significant differences were found between children implanted at before 12 months and between 12 and 16 months of age. CONCLUSIONS: The results of the analyzed follow-up data support the hypothesis that children implanted at before 24 months are expected to have better hearing performances. Nevertheless, these results are referred to a widely heterogeneous group of patients and the duration of auditory deprivation should be considered.

Entirely robotic cochlear implant surgery.

INTRODUCTION: Robot-assisted cochlear implant surgery (RACIS) as defined by the HEARO®-procedure performs minimal invasive cochlear implant (CI) surgery by directly drilling a keyhole trajectory towards the inner ear. Hitherto, an entirely robotic automation including electrode insertion has not been described yet. The feasability of using a newly developed, dedicated motorised device for automated electrode insertion in the first clinical case of entirely robotic cochlear implant surgery was investigated. AIM: The aim is to report the first experience of entirely robotic cochlear implantation surgery. INTERVENTION: RACIS with a straight flexible lateral wall electrode. PRIMARY OUTCOME MEASUREMENTS: Electrode cochlear insertion depth. SECONDARY OUTCOME MEASUREMENTS: The audiological outcome in terms of mean hearing thresholds. CONCLUSION: Here, we report on a cochlear implant robot that performs the most complex surgical steps to place a cochlear implant array successfully in the inner ear and render similar audiological results as in conventional surgery. Robots can execute tasks beyond human dexterity and will probably pave the way to standardize residual hearing preservation and broadening the indication for electric-acoustic stimulation in the same ear with hybrid implants.

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.

Cochlear reimplantation outcomes over 20 years: Expertise in reimplantation surgery and auditory-speech rehabilitation.

OBJECTIVES: The aim of this study was to present an institution's experience with cochlear reimplantation (CRI), to assess surgical challenges and post-operative outcomes and to increase the success rate of CRI. STUDY DESIGN: Retrospective single-institution study. SETTING: Tertiary medical center. METHODS: We retrospectively evaluated data from 76 reimplantation cases treated in a tertiary center between 2001 and 2022. Clinical features including etiology of hearing loss, type of failure, surgical issues, and auditory speech performance were analyzed. Categorical Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) scores were used to evaluate pre- and post-CRI outcomes. RESULTS: The CRI population comprises of 7 patients from our institute,69 referred patients from other centers. Device failure was the most common reason (68/76, 89.5 %) for CRI; in addition, there were 7 medical failures and 1 had both soft device failure. Medical failures included flap rupture and device extrusion, magnet migration, auditory neuropathy, leukoencephalopathy, foreign-body residue and meningitis. In 21/76 patients, the electrode technology was upgraded. The mean time to failure was 0.58-13 years, with a mean of 4.97 years. The mean (± SD) CAP and SIR scores before and after CRI were 5.2 ± 1.2 versus 5.5 ± 1.1 and 3.4 ± 1.1 versus 3.5 ± 1.1, respectively. Performance was poor in six patients with severe cochlear malformation, auditory nerve dysplasia, leukoencephalopathy, and epilepsy. CONCLUSION: CRI surgery is a challenging but relatively safe procedure, and most reimplanted patients experience favorable postoperative outcomes. Medical complications and intracochlear damage are the main causes of poor postoperative results. Therefore, adequate preoperative preparation and atraumatic CRI should be carried out for optimal results.

AI model for predicting adult cochlear implant candidacy using routine behavioral audiometry.

OBJECTIVE: To describe an AI model to facilitate adult cochlear implant candidacy prediction based on basic demographical data and standard behavioral audiometry. METHODS: A machine-learning approach using retrospective demographic and audiometric data to predict candidacy CNC word scores and AzBio sentence in quiet scores was performed at a tertiary academic center. Data for the model were derived from adults completing cochlear implant candidacy testing between January 2011 and March 2023. Comparison of the prediction model to other published prediction tools and benchmarks was performed. RESULTS: The final dataset included 770 adults, encompassing 1045 AzBio entries, and 1373 CNC entries. Isophoneme scores and word recognition scores exhibited strongest importance to both the CNC and AzBio prediction models, followed by standard pure tone average and low-frequency pure tone average. The mean absolute difference between the predicted and actual score was 15 percentage points for AzBio sentences in quiet and 13 percentage points for CNC word scores, approximating anticipated test-retest constraints inherent to the variables incorporated into the model. Our final combined model achieved an accuracy of 87 % (sensitivity: 90 %; precision: 80 %). CONCLUSION: We present an adaptive AI model that predicts adult cochlear implant candidacy based on routine behavioral audiometric and basic demographical data. Implementation efforts include a public-facing online prediction tool and accompanying smartphone program, an embedded notification flag in the electronic medical record to alert providers of potential candidates, and a program to retrospectively engage past patients who may be eligible for cochlear implantation based on audiogram results.

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.

Hearing rehabilitation in children with malformed ears: The endoscopic-assisted approach for cochlear implantation.

BACKGROUND: Cochlear implantation (CI) in children with malformed ears can be challenging through the standard surgical technique. Several alternative approaches have been described. The endoscopic-assisted approach can be chosen as an effective and safe surgical technique, overcoming the drawbacks of the traditional approach. MATERIAL: We further describe a combined technique based on a limited mastoidectomy with no posterior tympanotomy and an endoscopic transmeatal approach to the round window (RW): the electrode is driven from the mastoid to the middle ear through the attic. RESULTS: The concomitant endoscopic assistance allows for improved surgical vision, reducing the risk of major complications. The main advantages of this technique are related to better visualization of the RW for safe insertion of the electrode; avoidance of damage to the facial nerve (FN), due to direct visualization, and sparing the posterior tympanotomy; avoidance of subtotal petrosectomy, if not necessary. CONCLUSION: The purpose of this article, supported with a video file, is to describe step by step this endoscopic-assisted procedure in a patient with middle ear malformation.