Electrode migration and magnet dislocation are uncommon but clinically relevant complications following cochlear implant (CI) surgery. Most previously published studies are limited by small sample sizes, restricting the ability to precisely estimate incidence rates and risk factors. To determine the frequency, mechanisms, and clinical correlates of rare CI complications in one of the largest contemporary single-center CI cohorts. This retrospective study analyzed 1,035 CI surgeries performed between 2015 and 2025 at a tertiary referral center. Clinical, demographic, surgical, and audiologic data were extracted from institutional databases. Electrode migration was confirmed via imaging and surgical exploration. Electrode migration occurred in 16 cases (1.55

Background/Objectives: Cochlear implants (CIs) are a common treatment of severe-to-profound hearing loss and provide reasonable speech understanding, at least in quiet situations. However, their limited spectro-temporal resolution restricts sound quality, which is especially crucial for music appraisal. Many CI recipients wear a hearing aid (HA) on the non-implanted ear (bimodal users), which may enhance music perception by adding acoustic fine structure cues. Since it is unclear how the HA should be fitted in conjunction with the CI to achieve optimal benefit, this study aimed to systematically vary HA fitting parameters and assess their impact on music sound quality in bimodal users. Methods: Thirteen bimodal CI recipients participated in a listening experiment using a master hearing aid that allowed controlled manipulation of HA settings. Participants evaluated three music excerpts (pop with vocals, pop without vocals, classical) using the multiple-stimulus with hidden reference and anchor (MUSHRA) test. To assess the reliability of individual judgments, each participant repeated the test, and responses were analyzed with the eGauge method. Results: Most participants provided reliable and consistent sound quality ratings. Compared to a standard DSL v5.0 prescriptive fitting, modifications in compression settings and low-frequency gain significantly influenced perceived music quality. The effect of low-frequency gain adjustments was especially pronounced for pop music with vocals, indicating stimulus-dependent benefits. Conclusions: The study demonstrates that HA fitting for bimodal CI users can be optimized beyond standard prescriptive rules to enhance music sound quality by increasing low-frequency gain, particularly for vocal-rich pieces. Additionally, the testing method shows promise for clinical application, enabling individualized HA adjustments based on patient-specific listening preferences, hence fostering personalized audiology care.

OBJECTIVE:This study investigated whether the SONNET 2 audio processor's ambient noise reduction (ANR) algorithm improves speech recognition and listening effort in cochlear implant (CI) users as a function of different noise signals. DESIGN:Speech recognition and listening effort were measured in the presence of four different noise signals, including stationary and fluctuating noise, and including a speech masker. Speech was presented from the front (S0) and noise from two sources from the back (N ± 135). STUDY SAMPLE:20 adult CI users. RESULTS:With the ANR, speech recognition significantly improved in the presence of one stationary noise and in the presence of one fluctuating noise. The ANR had no significant effect on listening effort. CONCLUSIONS:When activating the ANR algorithm of the SONNET 2 audio processor, speech recognition improved in some conditions. Listening effort was equal in all conditions. In corresponding everyday situations, it can be recommended to use the ANR algorithm.

Although a cochlear implant (CI) can partially restore auditory function, CI recipients show alterations not only in auditory but also in visual cortical processing. Yet, it is not well understood how these visual changes relate to the CI outcome and to what extent these changes are induced by auditory deprivation and the limited CI input, respectively. Here, we present a prospective longitudinal electroencephalography study which examined the deprivation- and CI-induced alterations on cortical face processing by comparing visual evoked potentials (VEP) in CI users before and 6 months after implantation. A group of normal-hearing (NH) listeners served as a control. The participants performed a word-identification task and a face-categorization task to study the cortical processing of static and articulating faces in attended and unattended conditions. The CI candidates and CI users showed a reduced visual-cortex activation, a stronger functional connectivity between the visual and auditory cortex, and a reduced attention effect in the (extended) alpha frequency range (8-18 Hz) when compared to NH listeners. There was a positive correlation between the P1 VEP amplitude recorded before implantation and the speech recognition ability after implantation. Our results suggest that the CI users' alterations in cortical face processing are mainly induced by auditory deprivation and not by CI experience. Importantly, these deprivation-induced changes seem to be related to the CI outcome. Our results suggest that the visual P1 amplitude as recorded before implantation provides an objective index of cortical visual reorganization that may help predict the CI outcome.

Background Endovascular aortic aneurysm repair (EVAR) has become the standard procedure for treating infrarenal abdominal aortic aneurysms (AAA). Various associated complications can lead to open conversion (OC). Thorough follow-up after the procedure is mandatory for the early detection of complications. Persisting perfusion of the aneurysm, a so-called endoleak (EL), paired with structural instability because of aortic wall atrophy and impaired cell functionality induced by EVAR, results in a high risk for aortic rupture. Purpose The goal of this study was to detect the risk factors for elective and urgent OC as a result of EVAR-induced pathophysiological changes inside the aortic wall. Research Design Retrospective data analysis was performed on all open aortic repairs from January 2016 to December 2020. Data Collection and Analysis Fifty patients were identified as treated by OC for failure of an infrarenal EVAR. The patients were divided into two subgroups, here depending on the urgency of surgery. Statistical analysis of patient characteristics and outcomes was performed. Results The most common indications for OC were various types of EL (74%), resulting in an aortic rupture in 15 patients. Patients with insufficient or absent follow-up were treated more frequently in an emergency setting (16% vs. 63%). The mortality rate was higher in cases of emergency OC (3% vs. 26%). Conclusions Particularly in cases of insufficient or absent follow-up, complications such as EL pose an enormous risk for fatal aortic rupture.

In many cases, cochlear implants enable a significant improvement in speech recognition. However, sound quality is fundamentally restricted due to limited spectro-temporal cues. A conventional hearing aid is often used on the contralateral side, which opens up potential for improving sound quality through the additional transmission of acoustic features. In this context, two experiments aimed to systematically optimise the hearing aid fitting in the low-frequency range. The fitting based on the DSL v5.0 rule (Scolie et al., 2005) was always used as a reference. In the first experiment, a Master Hearing Aid (Grimm et al., 2006) was applied to simulate the hearing aid on the non-implanted side. This allowed all changes to the fitting to be carried out under controlled conditions. Building on this, real hearing aids were used in the second experiment to verify the results under conditions closer to everyday life. Various pieces of music were presented and the subjective perception of sound was recorded using different psychoacoustic methods (Abdellatif et al., 2022). Based on both experiments, it is shown that an increase in low-frequency gain relative to that proposed via DSL can lead to an improvement in sound quality [1] [2] [3].

Background Using Otoplan software, it is possible to measure the cochlea before cochlear implant surgery. Until now, computed tomography (CT) of the cochlea has been necessary for this purpose. The aim of this study was to find out whether measuring the cochlea with magnetic resonance imaging (MRI) using Otoplan is possible with the same accuracy.Methods The cochlea of 44 patients of the local cochlear implant centre was measured by Otoplan using high-resolution CT-bone and MRI images, and the determined lengths were compared.Results No significant difference was found between the cochlear lengths measured, regardless of whether the length measurement was based on a CT or an MRI data set.Conclusion For the determination of cochlear length prior to cochlear implant surgery, MRI images are just as suitable as CT images, therefore CT is not mandatory for length measurement by Otoplan, which could reduce the patient's radiation exposure.

Limited auditory input, whether caused by hearing loss or by electrical stimulation through a cochlear implant (CI), can be compensated by the remaining senses. Specifically for CI users, previous studies reported not only improved visual skills, but also altered cortical processing of unisensory visual and auditory stimuli. However, in multisensory scenarios, it is still unclear how auditory deprivation (before implantation) and electrical hearing experience (after implantation) affect cortical audiovisual speech processing.Here, we present a prospective longitudinal electroencephalography (EEG) study which systematically examined the deprivation- and CI-induced alterations of cortical processing of audiovisual words by comparing event-related potentials (ERPs) in postlingually deafened CI users before and after implantation (five weeks and six months of CI use). A group of matched normal-hearing (NH) listeners served as controls. The participants performed a word-identification task with congruent and incongruent audiovisual words, focusing their attention on either the visual (lip movement) or the auditory speech signal. This allowed us to study the (top-down) attention effect on the (bottom-up) sensory cortical processing of audiovisual speech.When compared to the NH listeners, the CI candidates (before implantation) and the CI users (after implantation) exhibited enhanced lipreading abilities and an altered cortical response at the N1 latency range (90-150 ms) that was characterized by a decreased theta oscillation power (4-8 Hz) and a smaller amplitude in the auditory cortex. After implantation, however, the auditory-cortex response gradually increased and developed a stronger intra-modal connectivity. Nevertheless, task efficiency and activation in the visual cortex was significantly modulated in both groups by focusing attention on the visual as compared to the auditory speech signal, with the NH listeners additionally showing an attention-dependent decrease in beta oscillation power (13-30 Hz).In sum, these results suggest remarkable deprivation effects on audiovisual speech processing in the auditory cortex, which partially reverse after implantation. Although even experienced CI users still show distinct audiovisual speech processing compared to NH listeners, pronounced effects of (top-down) direction of attention on (bottom-up) audiovisual processing can be observed in both groups. However, NH listeners but not CI users appear to show enhanced allocation of cognitive resources in visually as compared to auditory attended audiovisual speech conditions, which supports our behavioural observations of poorer lipreading abilities and reduced visual influence on audition in NH listeners as compared to CI users.

Objectives: This study’s objective was to evaluate Endurant II (Medtronic Inc, Minneapolis, Minnesota) stent graft’s early and midterm outcomes and compare the results according to the anatomic severity grade (ASG) scores. Methods: This was a retrospective study of patients treated with the Endurant II stent graft between January 2013 and May 2021. The patients were divided into 2 independent groups, including those with a low ASG score (score <14) and a high ASG score (score >14). Results: A total of 165 consecutive patients (89% males, age 74±8 years) were included. There were 110 (67%) patients in the low-score group and 55 (33%) patients in the high-score group. Technical success was achieved in all cases. Primary clinical success at 30 days was 100% and at 1 year was 96%. Median operative time was longer in the high-score group with no statistical significance (133 vs 120 minutes, p=0.116). The median dose area product of low-score patients (50.9 Gy·cm2; IQR 22.4–75.5 Gy·cm2) was significantly lower than high-score patients (85.0 Gy·cm2; IQR 46.5–127.9 Gy·cm2) with p=0.025. Median fluoroscopic time was lower in low-score patients (17 minutes; IQR 13–24 minutes) compared with high-score patients (19 minutes; IQR 16–23 minutes) without a significant difference at p=0.148. At a midterm follow-up of 32 months (range 2–63 months), combined complications (29% vs 8%, p<0.001) and implant-related complications (13% vs 4%, p=0.043) were higher in the high-score group. Systemic complications at 30 days were higher in the high-score group without a statistically significant difference (15% vs 11%, p=0.500). The Kaplan-Meier estimate of freedom from reintervention was significantly higher in the low-risk group at 1 (97% vs 90%), 2 (96% vs 88%), and 3 years (96% vs 85%) with (p=0.035). The cumulative survival rate was significantly higher in the low-score group than high-score group (p=0.001) at 1 (99% vs 87%), 2 (98% vs 85%), and 3 years (96% vs 82%). Conclusions: Endurant II endovascular aneurysm repair seems to be safe in both low-score and high-score patients. However, patients in the high-score group showed more implant-related complications and midterm mortalities than those in the low-score group.

Implanting clinics are responsible for the care process of their cochlear implant (CI) patients, from preoperative consultation to implantation and lifelong follow-up. The Remote Check (RC) app is part of the Cochlear™ Nucleus​ Smart App from Cochlear Ltd. and is designed to provide telemedicine support for annual follow-up care. In this multicenter study, follow-up appointments with the app and traditional CI follow-up were compared. Two groups of patients were recruited for this purpose. RC+ used the app, while RC- attended a traditional follow-up appointment on-site at the clinic/CI center. Up to 120 adult unilateral, bilateral, or bimodal CI users per study center (seven total) participated in the study. Data collected included questionnaire responses regarding the time and cost of the follow-up appointment, as well as satisfaction with it. Initial data showed a difference in time and cost for the two follow-up groups. While a follow-up appointment for RC- took an average of about 100 minutes (excluding travel time), it was 45 minutes for RC+. This contrasted with greater satisfaction with the follow-up appointment for RC-. About 50% of RC- could imagine using a telemedicine app for follow-up. When asked about their follow-up of choice, the majority of RC+ would prefer a follow-up appointment via app from home, while the majority of RC- would prefer an in-person on-site appointment, but just under 30% would prefer both alternately. A telemedicine app can usefully complement CI follow-up to reduce the time and effort required for this.

Objective: Hearing with a cochlear implant (CI) is difficult in noisy environments, but the use of noise reduction algorithms, specifically ForwardFocus, can improve speech intelligibility. The current eventrelated potentials (ERP) study examined the electrophysiological correlates of this perceptual improvement. Methods: Ten bimodal CI users performed a syllable-identification task in auditory and audiovisual conditions, with syllables presented from the front and stationary noise presented from the sides. Brainstorm was used for spatio-temporal evaluation of ERPs. Results: CI users revealed an audiovisual benefit as reflected by shorter response times and greater activation in temporal and occipital regions at P2 latency. However, in auditory and audiovisual conditions, background noise hampered speech processing, leading to longer response times and delayed auditorycortex-activation at N1 latency. Nevertheless, activating ForwardFocus resulted in shorter response times, reduced listening effort and enhanced superior-frontal-cortex-activation at P2 latency, particularly in audiovisual conditions. Conclusions: ForwardFocus enhances speech intelligibility in audiovisual speech conditions by potentially allowing the reallocation of attentional resources to relevant auditory speech cues. Significance: This study shows for CI users that background noise and ForwardFocus differentially affect spatio-temporal cortical response patterns, both in auditory and audiovisual speech conditions. & COPY; 2023 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Implantierende Kliniken tragen die Verantwortung für den Versorgungsprozess ihrer Cochlea Implantat (CI)-Patienten/Innen, von der präoperativen Beratung über die Implantation bis hin zur lebenslangen Nachsorge. Die Remote Check (RC) App ist Teil der Cochlear™ Nucleus​ Smart App von Cochlear Ltd. und dient der telemedizinischen Unterstützung der jährlichen Nachsorge. In dieser multizentrischen Studie wurden Nachsorgetermine mit der App und traditionelle CI-Nachsorge verglichen. Hierzu wurden zwei Gruppen von Patienten rekrutiert. RC+ nutzte die App, während RC- einen traditionellen Nachsorgetermin vor Ort in der Klinik/im CI-Zentrum wahrnahm. Bis zu 120 erwachsene unilaterale, bilaterale oder bimodale CI-Träger pro Studienzentrum (insgesamt sieben) nahmen an der Studie teil. Erhobene Daten umfassten Fragebogenantworten bezüglich des Zeit- und Kostenaufwands für den Nachsorgetermin, sowie die Zufriedenheit mit diesem. Erste Daten zeigten einen Unterschied in zeitlichem und finanziellem Aufwand für die beiden Nachsorgegruppen. Während ein Nachsorgetermin für RC- durchschnittlich etwa 100 Minuten (exkl. Fahrzeiten) in Anspruch nahm, waren es für RC+ 45 Minuten. Demgegenüber stand eine größere Zufriedenheit mit dem Nachsorgetermin für RC-. Etwa 50% von RC- könnte sich vorstellen eine telemedizinische App für die Nachsorge zu nutzen. Gefragt nach der Nachsorge ihrer Wahl, würde die Mehrheit von RC+ einen Nachsorgetermin per App von zu Hause aus bevorzugen, die Mehrheit von RC- einen persönlichen Vor-Ort-Termin, aber knapp 30 % beides im Wechsel. Eine telemedizinische App kann die CI-Nachsorge sinnvoll ergänzen, um den dafür aufzubringenden Aufwand zu reduzieren.

Objective: The aim of the study was to investigate if a directional microphone mode improves speech perception in noise and sound localization in experienced pediatric bilateral cochlear implant users. Methods: 15 bilaterally implanted children were included in the analysis. Speech perception in 4 noise conditions (S0N0, S0N90, S0N-90, S0N180) and sound localization were measured when using the OPUS 2 audio processor (omnidirectional mode) and the SONNET audio processor (omnidirectional and natural mode). Results: Speech perception in all 4 noise conditions was better with the SONNET natural mode than with the omnidirectional mode of either SONNET or OPUS 2. The root-mean-square error of the sound localization test was smaller with the natural mode of SONNET than with the omnidirectional mode of either SONNET or OPUS 2. The performance of the audio processors in the omnidirectional mode did not differ significantly except in the S0N0 condition of the speech perception test. Conclusion: The natural microphone mode of the SONNET audio processor improved speech perception in noise and sound localization in bilaterally implanted children.

Objective: This study aimed to derive a new scoring model from estimating the severity grade of mesenteric artery stenosis. We sought to analyze the relationship between the new scoring model and the development, treatment, and mortality of chronic mesenteric ischemia (CMI). Methods: This retrospective study included 242 patients (128 (53%) women and 114 (47%) men) with suspected CMI from January 2011 to December 2020. A weighted sum six-point score (CSI-score; the celiac artery is abbreviated by “C”, superior mesenteric artery by “S”, and inferior mesenteric artery by “I”) based on the number of affected vessels and the extent and grade of the stenosis or occlusion of the involved visceral arteries was derived by maximizing the area under the ROC curve. The calculated CSI-score ranged from 0 to 22. The patients were divided according to the best cut-off point into low-score (CSI-score < 8) and high-score (CSI-score ≥ 8) groups. Results: The area under the receiver operating characteristic curve (AUC) of the CSI-score was 0.86 (95% CI, 0.82–0.91). The best cut-off point of “8” represented the highest value of Youden’s index (0.58) with a sensitivity of 87% and specificity of 72%. The cohort was divided according to the cut-off point into a low-score group (n = 100 patients, 41%) and high-score group (n = 142 patients, 59%) and according to the clinical presentation into a CMI group (n = 109 patients, 45%) and non-CMI group (n = 133 patients, 55%). The median CSI-score for all patients was 10 (range: 0 -22). High-scoring patients showed statistically significant higher rates of coronary artery disease (54% vs. 36%, p = 0.007), chronic renal insufficiency (50% vs. 30%, p = 0.002), and peripheral arterial disease (57% vs. 16%, p < 0.001). A total of 109 (45%) patients underwent invasive treatment of the visceral arteries and were more often in the high-score group (69% vs. 11%, p < 0.001). Of those, 79 (72%) patients underwent primary endovascular treatment, and 44 (40%) patients underwent primary open surgery or open conversion after endovascular treatment. Sixteen (7%) patients died during the follow-up, with a statistically significant difference between high- and low-scoring patients (9% vs. 0%, p = 0.008). The score stratification showed that the percentage of patients treated with endovascular and open surgical methods, the recurrence of the stenosis or failure of the endovascular treatment, the need for a bypass procedure, and the mortality rates significantly increased in the subgroups. The CSI-score demonstrated an excellent ability to discriminate between patients who needed treatment and those who did not, with an AUC of 0.87 (95% CI, 0.82–0.91). Additionally, the CSI-score’s ability to predict the patients’ mortality was moderate, with an AUC of 0.73 (95% CI, 0.62–0.83). Conclusions: The new scoring model can estimate the severity grade of the stenosis of the mesenteric arteries. Our study showed a strong association of the score with the presence of chronic mesenteric ischemia, the need for treatment, the need for open surgery, and mortality.

A cochlear implant (CI) can partially restore hearing in individuals with profound sensorineural hearing loss. However, electrical hearing with a CI is limited and highly variable. The current study aimed to better understand the different factors contributing to this variability by examining how age affects cognitive functions and cortical speech processing in CI users. Electroencephalography (EEG) was applied while two groups of CI users (young and elderly; N = 13 each) and normal-hearing (NH) listeners (young and elderly; N = 13 each) performed an auditory sentence categorization task, including semantically correct and incorrect sentences presented either with or without background noise. Event-related potentials (ERPs) representing earlier, sensory-driven processes (N1-P2 complex to sentence onset) and later, cognitive-linguistic integration processes (N400 to semantically correct/incorrect sentence-final words) were compared between the different groups and speech conditions. The results revealed reduced amplitudes and prolonged latencies of auditory ERPs in CI users compared to NH listeners, both at earlier (N1, P2) and later processing stages (N400 effect). In addition to this hearing-group effect, CI users and NH listeners showed a comparable background-noise effect, as indicated by reduced hit rates and reduced (P2) and delayed (N1/P2) ERPs in conditions with background noise. Moreover, we observed an age effect in CI users and NH listeners, with young individuals showing improved specific cognitive functions (working memory capacity, cognitive flexibility and verbal learning/retrieval), reduced latencies (N1/P2), decreased N1 amplitudes and an increased N400 effect when compared to the elderly. In sum, our findings extend previous research by showing that the CI users’ speech processing is impaired not only at earlier (sensory) but also at later (semantic integration) processing stages, both in conditions with and without background noise. Using objective ERP measures, our study provides further evidence of strong age effects on cortical speech processing, which can be observed in both the NH listeners and the CI users. We conclude that elderly individuals require more effortful processing at sensory stages of speech processing, which however seems to be at the cost of the limited resources available for the later semantic integration processes.

A cochlear implant (CI) is an auditory prosthesis which can partially restore the auditory function in patients with severe to profound hearing loss. However, this bionic device provides only limited auditory information, and CI patients may compensate for this limitation by means of a stronger interaction between the auditory and visual system. To better understand the electrophysiological correlates of audiovisual speech perception, the present study used electroencephalography (EEG) and a redundant target paradigm. Postlingually deafened CI users and normal-hearing (NH) listeners were compared in auditory, visual and audiovisual speech conditions. The behavioural results revealed multisensory integration for both groups, as indicated by shortened response times for the audiovisual as compared to the two unisensory conditions. The analysis of the N1 and P2 event-related potentials (ERPs), including topographic and source analyses, confirmed a multisensory effect for both groups and showed a cortical auditory response which was modulated by the simultaneous processing of the visual stimulus. Nevertheless, the CI users in particular revealed a distinct pattern of N1 topography, pointing to a strong visual impact on auditory speech processing. Apart from these condition effects, the results revealed ERP differences between CI users and NH listeners, not only in N1/P2 ERP topographies, but also in the cortical source configuration. When compared to the NH listeners, the CI users showed an additional activation in the visual cortex at N1 latency, which was positively correlated with CI experience, and a delayed auditory-cortex activation with a reversed, rightward functional lateralisation. In sum, our behavioural and ERP findings demonstrate a clear audiovisual benefit for both groups, and a CI-specific alteration in cortical activation at N1 latency when auditory and visual input is combined. These cortical alterations may reflect a compensatory strategy to overcome the limited CI input, which allows the CI users to improve the lip-reading skills and to approximate the behavioural performance of NH listeners in audiovisual speech conditions. Our results are clinically relevant, as they highlight the importance of assessing the CI outcome not only in auditory-only, but also in audiovisual speech conditions.

The use of cochlear implants (CI) is the common treatment to counteract severe-profound hearing loss. CI often allow reasonable speech understanding but are generally limited in terms of spectro-temporal resolution. Many CI recipients use a hearing aid (HA) on the non-implanted ear (so called bimodal patients) that complements the electrical stimulation of the CI by providing acoustical fine structure information. Amongst others, this might be especially beneficial for music appraisal. However, it is not clear how the HA should be fitted in conjunction with the CI in order to provide the best sound quality.The purpose of this study was to vary different fitting parameters of the HA systematically and to determine the resulting music sound quality. To this end, a master hearing aid was used in order to have controlled access to the different parameters. Three different music excerpts (pop with and without vocals, classic) were presented to 13 bimodally fitted CI users and the sound quality was assessed using the “multiple-stimulus with hidden reference and anchor” (MUSHRA) test. Since the goal was to gain information on possible improvement of fitting, a complete retest was performed and individual reliability of the assessments was determined by the eGauge method.It could be shown that most of the listeners were able to provide reliable sound quality judgements. In terms of HA fitting it turned out that changing compression and varying low frequency gain had a significant effect compared to a standard prescriptive fitting based on DSL v5.0. However, especially the effect of changing low frequency gain depended on the music excerpts presented, since pop music with vocals revealed the largest effect.The study gives evidence that hearing aid fitting can be optimized relative to a standard prescriptive rule in order to improve music sound quality in bimodal CI users. Moreover, the method might be helpful in a clinical setting to determine the best fitting based on individual results.### Competing Interest StatementThe first author (KHAA) was financially supported by a research grant (IIR-1934) of Cochlear Ltd. The other authors declare no competing interests. The study was designed by the authors in collaboration with Cochlear Ltd. Data collection, analysis and the decision to publish were all solely accounted for by the authors.### Clinical TrialDRKS00016778### Funding StatementThis study was funded by Cochlear Ltd. (Reference IIR-1934)### Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:This study was approved by the Institutional Review Board of the Medical Faculty of the University of Cologne (Reference 18-383). All subjects provided informed consent prior to participation.I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.YesAll data produced in the present study are available upon reasonable request to the author

Cochlear implants (CIs) allow to restore the hearing function in profoundly deaf individuals. Due to the degradation of the stimulus by CI signal processing, implanted individuals with single-sided deafness (SSD) have the specific challenge that the input highly differs between their ears. The present study compared normal-hearing (NH) listeners (N = 10) and left- and right-ear implanted SSD CI users (N = 10 left, N = 9 right), to evaluate cortical speech processing between CI- and NH-ears and to explore for side-of-implantation effects. The participants performed a two-deviant oddball task, separately with the left and the right ear. Auditory event-related potentials (ERPs) in response to syllables were compared between proficient and non-proficient CI users, as well as between CI and NH ears. The effect of the side of implantation was analysed on the sensor and the source level. CI proficiency could be distinguished based on the ERP amplitudes of the N1 and the P3b. Moreover, syllable processing via the CI ear, when compared to the NH ear, resulted in attenuated and delayed ERPs. In addition, the left-ear implanted SSD CI users revealed an enhanced functional asymmetry in the auditory cortex than right-ear implanted SSD CI users, regardless of whether the syllables were perceived via the CI or the NH ear. Our findings reveal that speech-discrimination proficiency in SSD CI users can be assessed by N1 and P3b ERPs. The results contribute to a better understanding of the rehabilitation success in SSD CI users by showing that cortical speech processing in SSD CI users is affected by CI-related stimulus degradation and experience-related functional changes in the auditory cortex.

Hearing with a cochlear implant (CI) is limited compared to natural hearing. Although CI users may develop compensatory strategies, it is currently unknown whether these extend from auditory to visual functions, and whether compensatory strategies vary between different CI user groups. To better understand the experience-dependent contributions to multisensory plasticity in audiovisual speech perception, the current event-related potential (ERP) study presented syllables in auditory, visual, and audiovisual conditions to CI users with unilateral or bilateral hearing loss, as well as to normal-hearing (NH) controls. Behavioural results revealed shorter audiovisual response times compared to unisensory conditions for all groups. Multisensory integration was confirmed by electrical neuroimaging, including topographic and ERP source analysis, showing a visual modulation of the auditory-cortex response at N1 and P2 latency. However, CI users with bilateral hearing loss showed a distinct pattern of N1 topography, indicating a stronger visual impact on auditory speech processing compared to CI users with unilateral hearing loss and NH listeners. Furthermore, both CI user groups showed a delayed auditory-cortex activation and an additional recruitment of the visual cortex, and a better lip-reading ability compared to NH listeners. In sum, these results extend previous findings by showing distinct multisensory processes not only between NH listeners and CI users in general, but even between CI users with unilateral and bilateral hearing loss. However, the comparably enhanced lip-reading ability and visual-cortex activation in both CI user groups suggest that these visual improvements are evident regardless of the hearing status of the contralateral ear.