Objective: To report on a series of three cases in which problems with rotating magnets (blocked rotation, demagnetization) occurred in cochlear implants and to resolve these problems without surgical intervention. Methods: Of the 3635 devices with rotating magnets implanted at this tertiary referral hospital, 2 exhibited rotation blockage (associated with misalignment of the coil or audio processor), and 1 was partially demagnetized in a 1.5 T MRI scanner. Results: One blockage resolved spontaneously without intervention. The second blockage was resolved in the static field of a 3T MRI scanner, where the demagnetized magnet was also re-magnetized to its original strength. Surgical intervention or re-implantation was not necessary in either case. Conclusions: Surgical intervention or re-implantation is not primarily required in the event of problems with the rotating implant magnet. Prior to surgery, technical analysis can lead to a conservative solution.

In cochlear implant (CI) recipients, measurement of the electrically evoked compound action potential (ECAP) is used in clinical routine to prove the electrode-nerve interface and to support fitting, especially in very young children. To record an ECAP amplitude growth function (AGF), electrical stimuli are presented at increasing intensities up to the maximum acceptable loudness (MAL). However, a continuously monotonically rising sound can quickly be perceived as unpleasant and thus impair the success rate of ECAP threshold determination. The present study investigates whether perceptual and objective parameters, which are involved in ECAP measurements, depend on the type of stimulus presentation. In 27 subjects with a CI (28 implants), stimuli of five different AGF patterns were presented ten times in random order at a medial electrode contact, resulting in a total of 50 AGFs per implant. One pattern (Pclin) in which the stimuli increase strictly monotonically is already implemented in the clinical software (MAESTRO). The present study also employed rhythmic patterns and patterns with pauses. The behavioral threshold (THR), the maximum comfortable level (MCL), the MAL, and objective ECAP threshold were analyzed. ECAP threshold values did not change significantly when different stimulus paradigms were applied. Rhythmic AGF patterns were perceived as less unpleasant and enabled a higher MAL compared to Pclin. This in turn led to improved ECAP threshold determination, with the success rate rising to 86.7%, compared to 79.1% for Pclin.

Cochlear implants (CIs) enable hearing via direct electrical stimulation of the spiral ganglion neurons (SGN). Outcomes with a CI depend, in part, on the number and excitability of the SGNs. In an animal model, we introduced the Failure Index (FI) as an electrically-evoked compound action potential (eCAP)-derived marker of cochlear health. The FI informs about the presence, site, and size of SGN lesions. Here, we translated the FI to clinical recordings from human MED-EL CI users. In this retrospective study, we included patient data recorded between 2016 and 2024 from 199 ears with postlingual hearing loss and 79 ears with prelingual hearing loss. The averaged FI values over all contacts of the array were stable within the analysis period (3 rd month to 1 st year postoperatively). The FI increased with age and was elevated in etiologies associated with higher SGN loss. Using 3D reconstruction from cone-beam computed tomography scans, we confirmed that the FI was independent of electrode-to-modiolus distance (0.1–2.5 mm). The FI showed individual patterns along the array, with maxima usually found at basal contacts, corresponding to reduced neural health at high-frequency cochlear regions. In a selected group of postlingual-deaf ears, we found higher correlation coefficients between speech-perception scores and the FI compared to other eCAP-derived markers (i.e., threshold, slope, and amplitude). These results were in line with the hypothesis that the FI may serve as a clinical tool to identify implanted ears with reduced neural health and to identify contacts stimulating areas of reduced SGN survival and integrity.

OBJECTIVE:This study examined if the amplitude growth function (AGF) of the electrically evoked compound action potential (ECAP) can objectively predict the perceptual loudness growth function (LGF) in cochlear implant (CI) users. METHODS:ECAP AGFs were measured in 16 CI users across all active electrodes using the MED-EL AutoART fine-grain procedure. Perceptual LGFs were obtained with psychophysical loudness scaling at stimulation rates between 150 and 1200 pulses per second (pps). A third experiment collected ECAP and LGF data simultaneously at 80 pps. Both physiological and perceptual functions were normalized to their dynamic ranges, and a power-law transformation was fitted to model the transformation between ECAP amplitude and perceived loudness. The effects of stimulation rate and electrode position on the model parameters were examined statistically, and the model's predictive accuracy was assessed using a goodness-of-fit (R²) analysis. RESULTS:Loudness growth functions showed a systematic rate dependency: shifting from compressive at 80 pps to expansive at 1200 pps. Electrode-specific effects were less pronounced. The power-law exponent increased significantly with stimulation rate (p < 10⁻¹⁵), indicating steeper loudness growth at higher rates. The transformation model was remarkably accurate predicting perceptual loudness: 66% of fits yielded R²>0.8 and 45% >0.9, demonstrating strong correspondence between physiological and perceptual growth functions. CONCLUSIONS:A strong, systematic relationship exists between ECAP AGFs and perceptual loudness growth across stimulation rates in CI users. Modeling loudness growth from ECAP data provides a viable path toward objective, physiology-based individualization of compression functions in future CI fittings.

Auditory brainstem implants (ABI) can enable hearing sensation through electrical stimulation of the cochlear nucleus. The basic stimulation and signal coding strategies of the ABI are based on those of the cochlear implant. This may not always be optimal, and ABI-specific strategies may be preferred. In a cohort of ten ABI users, we examined the feasibility of measuring local evoked potentials (LEP) via fine-grained stimulation with a forward masking paradigm. We introduce a new baseline-dependent definition of LEP amplitude for analyzing the LEP amplitude growth function to obtain threshold stimulation levels and slope values. The processing of biphasic pulses by the cochlear nucleus and the influence of the leading phase polarity were examined. There were no statistically significant differences in LEP thresholds or slopes between cathodic and anodic leading pulses. LEP thresholds measured with cathodic leading pulses (r = 0.77, t31 = 6.81, p < 0.0001) and anodic leading pulses (r = 0.70, t27 = 45.14, p < 0.0001) correlated significantly with perceptual hearing thresholds. The correlation analysis was impacted by outlier values, especially in the case of LEP thresholds measured with anodic leading pulses. Cathodic leading pulses had significantly shorter LEP peak latencies (t104.8 = 2.63, p < 0.01). These results show that the cathodic leading pulses are superior for eliciting LEPs. We suggest that cathodic leading pulses should be the basis for ABI-specific coding strategies.

Cochlear implants (CIs) enable hearing with the deafened ear, via direct, electrical stimulation of the spiral ganglion neurons (SGN). Thus, the outcome depends on the number and excitability of the SGNs. We recently established the electrically-evoked compound action potential (eCAP)-derived Failure Index (FI) as cochlear-health marker in the animal model. The FI informs about the presence, site, and size of a SGN lesion. Here, we translated the FI to clinical recordings of MED-EL CI users. For the retrospective study, we selected patient data from the database of the German Hearing Center Hannover recorded 2017 to 2024. We included 199 post-lingually and 79 pre-lingually deafened ears. Averaged FIs over all contacts of a CI were stable within the analysis period (3 rd month to 1 st year postoperatively). The FI increased with age and was elevated for etiologies associated with higher SGN loss. Utilizing 3D information from cone beam-computed tomography scans, we confirmed that the FI was independent of distance (0.1-2.5 mm) to the modiolus. The FI showed individual patterns along the array with maxima usually at basal contacts, corresponding to elevated SGN loss at high frequencies. In a selected group of post-lingually deaf ears, we confirmed the correlation of the FI with speech perception in quiet and in noise (n=28, r 2 =0.12-0.55). Thus, we propose the FI as promising clinical tool to identify CI-implanted ears with reduced neural health and contacts close to areas of SGN loss. Thereby, it can serve to guide speech-processor fitting to optimize CI outcomes.

Einleitung Eine Elektrodenmigration bei Patienten mit auditorischem Hirnstammimplantat (ABI) kann – insbesondere bei Kindern – zur Ablehnung des Sprachprozessors führen. Die bildgebende Überprüfung der Elektrodenlage ist aufwändig und stellt zudem eine Strahlenbelastung dar. Für die regelmäßigen Nachsorgeuntersuchen ist die Messung des elektrisch evozierten Potenzials (LEP) (Gärtner et al. 2021, DOI: 10.1371/journal.pone.0249535) eine Alternative.

Objectives: This study aims to synthesize current knowledge and outcomes related to pediatric auditory brainstem implantation (ABI) in children with severe inner ear malformations (IEMs). It highlights the clinical management practices, challenges, and potential future directions for consensus development in this field. Methods: A systematic review of findings presented at the Third International Pediatric ABI Symposium organized by the Hacettepe Cochlear Implant team between 3 and 5 September 2020 was conducted, incorporating data from 41 departments across 19 countries. Relevant clinical outcomes, imaging techniques, surgical approaches, and rehabilitation strategies were analyzed to identify key trends and variability in practices. Results: The review indicates that children receiving ABIs exhibit diverse auditory outcomes influenced by individual anatomical variations and developmental factors. Early implantation, particularly before the age of three, positively correlates with better auditory and language development. Multicenter experiences underscore the necessity of tailored decision-making, which considers both surgical candidacy and comprehensive rehabilitation resources. Discussion:: The variability in outcomes emphasizes the need for improved consensus and guidelines regarding eligibility, surgical techniques, and multidisciplinary rehabilitation approaches. Notable complications and the necessity for thorough imaging assessments were also identified as critical components affecting clinical decisions. Conclusion: A formal consensus statement is warranted to standardize best practices in ABI management. This will not only enhance patient outcomes but also guide future research efforts to address the remaining challenges in the treatment of children with severe IEMs. Enhanced collaboration among team members will be pivotal in achieving these objectives.

Introduction Electrode migration in patients with auditory brainstem implant (ABI) can lead to refusal to use the speech processor, especially in children. Imaging verification of electrode location is costly and also represents radiation exposure. For regular follow-up examinations, measurement of the local evoked potential (LEP) (Gärtner et al. 2021, DOI: 10.1371/journal.pone.0249535) is an alternative.

Introduction Hearing impaired people describe different problems in everyday communication. So far, it is unclear how the perception of emotional parts of the speaker's voice changes after CI fitting and how they affect the severity of the subjectively perceived handicap.

Introduction:In a previous study, an inner ear catheter was used to deliver low- and high-dose steroids into the cochlea prior to cochlear implant electrode insertion. With this approach, more apical regions of the cochlea could be reached and a reduction of electrode impedances in the short term was achieved in cochlear implant recipients. Whether intracochlear application of drugs via the catheter is a safe method also for patients with residual hearing has not been investigated hitherto. The aim of the present study was therefore to investigate the effect of intracochlear triamcinolone application in cochlear implant recipients with residual hearing. Patients and methods:Patients with residual hearing were administered triamcinolone-acetonide (4 mg/ml; n = 10) via an inner ear catheter just prior to insertion of a MED-EL FLEX28 electrode. Impedances were measured at defined time points (intra-operatively, post-operatively and at first fitting) and retrospectively compared with a control group (no steroid application) and low- and high-dose group. Hearing thresholds were measured preoperatively, 3 days after surgery and at first fitting by pure tone audiometry. Pre- to postoperative hearing loss was determined at first fitting and compared to results from a previous study. Results:The median hearing loss after implantation (125-1,500 Hz) was 20.6 dB. Four patients (40%) showed a median hearing loss of less than 15 dB, three patients (30%) between 15 and 30 dB and three patients (30%) more than 30 dB. The median hearing loss was similar to the results obtained from our previous study showing a median hearing loss of 24 dB when using FLEX28 electrode arrays. Conclusion:No difference in residual hearing loss was found when comparing application of triamcinolone-acetonide using an inner ear catheter prior to the insertion of a FLEX28 electrode array to the use of the FLEX28 electrode array without the catheter. Thus, we conclude that application of drugs to the cochlea with an inner ear catheter could be a feasible approach in patients with residual hearing.

Einführung Auch wenn Cochlea-Implantate (CI) mittlerweile bei Kindern neben den Hörgeräten eine Erfahrungs-basierte Versorgung ist, chirurgische Komplikationen selten sind, ist die Reimplantation und das Re-Fitting eine spezifische pathophysiologische Herausforderung bei Patienten nach CI-abhängiger cerebraler Reifung implantiert vor 20 Jahren. In einer retrospektiven Studie berichten wir über 28 Patienten, die als Kind CI-versorgt wurden und im jungen Erwachsenenalter ohne medizinischen oder technischen Grund reimplantiert wurden.

Introduction Cochlear Implants as well as conventional hearing aids are part of the well experienced therapy strategy in children. Surgical complications in CI are rare. But reimplantation and re-Fitting in young adolescents, implanted in childhood, are a specific pathophysiological challenge. In this retrospective study we are reporting about 28 patient, implanted in childhood and asking for reimplantation because of expecting better speech understanding.

Einleitung Hörgeschädigte beschreiben unterschiedliche Probleme in der Alltagskommunikation. Bisher ist es unklar, wie sich die Wahrnehmung von emotionalen Anteilen der Sprecherstimme nach einer CI-Versorgung verändert und wie sich diese auf die Schwere des subjektiv empfundenen Handicaps auswirken.Material und

A percentage (i.e., 5.6%) of Cochlear Implant (CI) users reportedly experience unwanted facial nerve stimulation (FNS). For some, the effort to control this problem results in changing stimulation parameters, thereby reducing their hearing performance. For others, the only viable solution is to deactivate the CI completely. A growing body of evidence in the form of case reports suggests that undesired FNS can be effectively addressed through re-implantation with an Oticon Medical (OM) Neuro-Zti implant. However, the root of this benefit is still unknown: is it due to surgical adjustments, such as varied array geometries and/or positioning, or does it stem from differences in stimulation parameters and/or grounding? The OM device exhibits two distinct features: (1) unique stimulation parameters, including anodic leading pulses and loudness controlled by pulse duration-not current-resulting in lower overall current amplitudes; and (2) unconventional grounding, including both passive (capacitive) discharge, which creates a pseudo-monophasic pulse shape, and a 'distributed-all-polar' (DAP) grounding scheme, which is thought to reduce current spread. Unfortunately, case reports alone cannot distinguish between surgical factors and these implant-related ones. In this paper, we present a novel follow-up study of two CI subjects who previously experienced FNS before re-implantation with Neuro-Zti implants. We used the Oticon Medical Research Platform (OMRP) to stimulate a single electrode in each subject in two ways: (1) with traditional monopolar biphasic cathodic-first pulses, and (2) with distinct OM clinical stimulation. We progressively increased the stimulation intensity until FNS occurred or the sound became excessively loud. Non-auditory/FNS sensations were observed with the traditional stimulation but not with the OM clinical one. This provides the first direct evidence demonstrating that stimulation parameters and/or grounding-not surgical factors-play a key role in mitigating FNS.

OBJECTIVES:Temporal bone fracture can cause posttraumatic deafness. Sequelae like ossification or obliteration of the cochlea can impact the outcome of cochlear implantation. This study highlights the effect of localisation of the fracture to morphologic, electric and functional criteria.METHODS:The study group consists of patients suffering from hearing loss caused by temporal bone fracture (n = 61 ears). Patients were divided into otic capsule sparing (OCS) and otic capsule involving (OCI) fractures. The OCI group was additionally divided into subgroups with or without signs of ossification inside the cochlea. Postoperative imaging, hearing tests and electrode impedances were analysed.RESULTS:The results of postoperative hearing rehabilitation showed lower speech understanding scores for the OCI group, especially for the ossification group. OCI fractures with signs of ossification showed increased impedances. Patients in the OCI group suffered more frequently from facial nerve stimulation (FNS). FNS was most frequently observed within the ossification group.CONCLUSION:Cochlear implantation in patients with temporal bone fracture is adequate therapy for the treatment of fracture-induced deafness. In long-term observation, these patients show comparable results with regular cochlear implant (CI) patients. Implantation should be performed as soon as possible after hearing loss, before obstructing obliteration or ossification of the cochlea start.

We report the case of a woman, who was bilaterally supplied with hearing aids at the age of 12 years. 7 years later, she was provided with a cochlear implant (CI) on the right side due to progressive hearing impairment. After another 13 months, a CI was implanted also on the left side. Speech comprehension developed very well. 10 months later, the patient complained about fluctuating hearing perception with her left CI, especially after sneezing, yawning and blowing her nose. This hearing impairment could be provoked by Valsalva maneuver and was associated with an increase of electrode impedances. Pressure onto the skin above the implant led immediately decrease impedances. An integrity test of all internal and external parts of the CI did not reveal any kind of failure. Suspicion fell upon some possible air inclusion underneath the skin and above the implant case. Imaging showed that the implant was located in the rear part of the pneumatized mastoid and confirmed the hypothesis. First, non-invasive interventions were carried out, including re-programming the reference electrode from case to ring, application of a stronger magnet and compression bandages, and nasal spray for better ventilation. Since the problem remained, a revision surgery was indicated. The implant was moved in a cranial and posterior direction. One day after surgery, the CI was switched-on again. No parameters of the speech processors’ map needed to be change. The patient has not had the fluctuating hearing perception since.

Wir berichten den Fall einer heute 22 Jahre alten Frau. In ihrem 12. Lebensjahr wurden aufgrund einer progredienten Hörminderung beidseits Hörgeräte verordnet, die die Patientin seit ihrem 16. Lebensjahr ständig trug. Drei Jahre später wurde sie zunächst rechts, nach weiteren 13 Monaten auch links mit einem Cochlea-Implantat (CI) versorgt. Das Sprachverstehen entwickelte sich gut. Auf der linken Seite registrierte die Patientin etwa 10 Monate später Lautheitsschwankungen, zunächst nach Niesen, Gähnen und Nase putzen, später vermehrt und täglich. Die Hörverschlechterung ließ sich mit dem Valsalva-Manöver provozieren und ging mit einem Anstieg der Impedanzen der Elektrodenkontakte einher. Druckeinwirkung auf die Haut über dem Implantat ließ die Impedanzen schlagartig abfallen. Eine technische Überprüfung von CI und Sprachprozessor ergab keinen Hinweis auf einen Defekt. Der Verdacht fiel auf einen möglichen Lufteinschuss unter der Haut über dem Implantat. Es zeigte sich in der Bildgebung, dass das eingesetzte CI über dem hinteren Teil des sehr ausgeprägten pneumatisierten Mastoids liegt, dort auch dann etwas eingesenkt ist, sodass eine möglicherweise breite Luftverbindung aus dem Mastoid um das Implantat herum besteht. Verschiedene Maßnahmen wie Umprogrammieren der Referenzelektrode von Case- auf Ringelektrode, Einsetzen eines stärkeren Magneten, Anlegen eines Druckverbands sowie Anwendung eines Nasensprays wurden ohne Erfolg durchgeführt. Damit war eine Revision mit Verlagerung des CIs nach kranial und posterior indiziert. Das Implantat wurde bereits einen Tag nach der Operation wieder in Betrieb genommen. Die Einstellungen des Sprachprozessors wurden überprüft, mussten jedoch nicht angepasst werden. Der schwankende Höreindruck ist seitdem nicht wieder aufgetreten.

Anatomical malformations, obliterations of the cochlea, or re-implantations pose particular challenges in cochlear implantation. Treatment methods rely on radiological and intraoperative findings and include incomplete insertion, the implantation of a double array, and radical cochleostomy. In addition, a stiff electrode array, e.g., the IE stiff (IES) custom-made device (CMD, MED-EL), was prescribed individually for those special cases and pre-inserted prior to facilitate cochlear implantation in challenging cases. Data on outcomes after implantation in obliterated cochleae are usually based on individual case reports since standardised procedures are lacking. A retrospective analysis was conducted to analyse our cases on obliterated cochleae treated with MED-EL devices in order to allow the different cases to be compared. Impedances and speech perception data of patients treated with the IES CMD and the double array were retrospectively compared to patients treated with a STANDARD or FLEX electrode array (the REGULAR group). Patients with a Split-Array CMD had a poor speech perception when compared to patients treated with the IES CMD device. Thus, the IES CMD can successfully be used in patients with obliterated cochleae who would otherwise be non-users, candidates for a Split-Array CMD, or candidates for partial insertion with insufficient cochlear coverage.

Objectives To describe the influence of stimulus parameters on aberrant facial nerve stimulation in cochlear implant users. Methods Retrospective case series (three ears - two patients). Cochlear implant patients with severe facial nerve stimulation and degraded speech comprehension who underwent re-implantation with Neuro Zti EVO (Oticon Medical). Results In all three ears, side effects evoked by aberrant facial nerve stimulation could be resolved and thereby speech comprehension was improved. Conclusions Aberrant facial nerve stimulation in cochlear implant patients was successfully resolved by re-implantation. We hypothesize that one or more of the specific stimulus paramet ers are responsible for this success: combined common ground and monopolar stimulation mode, asymmetric pulse waveform with active anodic leading first phase followed by slow capacitive discharge, and pulse width modulation for loudness coding.