Evaluation of an impedance-based method to monitor the insertion of the electrode array during cochlear implantation.

PURPOSE: Cochlear implantation is a prevalent remedy for severe-to-profound hearing loss. Optimising outcomes and hearing preservation, and minimising insertion trauma, require precise electrode placement. Objective monitoring during the insertion process can provide valuable insights and enhance surgical precision. This study assesses the feasibility and performance of an impedance-based method for monitoring electrode insertion, compared to the surgeon's feedback. METHODS: The study utilised the Insertion Monitoring Tool (IMT) research software, allowing for real-time measurement of impedance and evoked compound action potential (eCAP) during electrode insertion in 20 patient implantations. This enabled an impedance-based method to continuously assess the status of each electrode during the insertion process. The feasibility and performance was evaluated and compared to the surgeon's feedback approach. eCAP measurements focused merely on feasibility without searching specific responses. RESULTS: The IMT demonstrated feasibility in measuring real-time impedances and eCAP during the insertion of the electrode array. The impedance-based method exhibited potential for accurately monitoring the insertion depth with a high success rate. However, further development is needed to improve the number of usable contacts. CONCLUSIONS: Objective monitoring with the impedance-based method shows promise as a valuable tool to enhance the precision of cochlear implant electrode insertion respecting insertion distance estimation. The IMT research software proved feasible in recording real-time impedances and eCAP during electrode insertion. While this impedance-based method exhibits high success rates, further improvements are required to optimise the number of usable contacts. This study highlights the potential of objective monitoring techniques to enhance cochlear implantation outcomes.

Metronome-guided cochlear implantation for slower and smoother insertions of lateral wall electrodes.

INTRODUCTION: Achieving a slow and smooth electrode array insertion is paramount for preserving structural and functional integrity during cochlear implantation. This controlled study evaluates the efficacy of a metronome-guided insertion technique in enhancing the smoothness and speed of electrode array insertions. METHODS: In a prospective cohort study, patients undergoing cochlear implant surgery between 2022 and 2023 with lateral wall electrode arrays were included. Metronome guidance was delivered through an acoustic signal via headphones during electrode array insertion in cochlear implantation and compared to a control group without metronome-guidance. RESULTS: In total, 37 cases were evaluated, including 25 conventional insertions and 12 metronome-guided insertions. The results indicate that metronome-guided insertions were significantly slower (- 0.46 mm/s; p < 0.001) without extending the overall procedure time. This can be attributed to fewer paused sections observed in the metronome-guided technique. Moreover, metronome-guided insertions exhibited superior performance in terms of insertion smoothness and a reduced number of re-gripping events. CONCLUSIONS: The findings support the recommendation for the systematic application of metronome guidance in the manual insertion of cochlear implant electrode arrays, emphasizing its potential to optimize surgical outcomes.

Electrically evoked compound action potentials are associated with the site of intracochlear stimulation.

OBJECTIVES: Objective measurements to predict the position of a cochlear electrode during cochlear implantation surgery may serve to improve the surgical technique and postoperative speech outcome. There is evidence that electrically evoked compound action potentials (ECAP) are a suitable approach to provide information about the site of stimulation. This study aims to contribute to the knowledge about the association between the intraoperative intracochlear ECAP characteristics and the site of stimulation. METHODS: In a retrospective cohort study, patients undergoing cochlear implant surgery with flexible lateral wall electrode arrays (12 stimulating channels) between 2020 and 2022 were analyzed. The CDL was measured using a CT-based clinical planning software. ECAP were measured for all electrode contacts and associated to the CDL as well as to the site of stimulation in degree. RESULTS: Significant differences among the amplitudes and slopes for the individual stimulated electrode contacts at the stimulation sites of 90°, 180°, 270°, 360°, 450° and 540° were found. The values showed a trend for linearity among the single electrodes. CONCLUSIONS: ECAP characteristics correlate with the electrode's position inside the cochlea. In the future, ECAP may be applied to assess the intracochlear position inside the cochlea and support anatomy-based fitting.

[Virtual DEGUM-certified course in the head and neck region-a useful complement to conventional course formats?] / Virtuell abgehaltene DEGUM-zertifizierte Kurse im Kopf-Hals-Bereich ­ eine sinnvolle Ergänzung zum konventionellen Kursformat?

BACKGROUND: Training in clinical ultrasound has become highly relevant for working as an otorhinolaryngologist. While there is a high demand for standardized and certified training courses, until recently, there was no possibility to attend web-based and exclusively virtual head and neck ultrasound courses certified by the Deutsche Gesellschaft für Ultraschall in der Medizin (DEGUM; German Society for Ultrasound in Medicine). OBJECTIVE: The aim of this study was to provide a qualitative and semi-quantitative analysis of the first purely virtual DEGUM-certified head and neck ultrasound courses. MATERIALS AND METHODS: In 2021, three purely web-based DEGUM-certified head and neck ultrasound courses were carried out and then qualitatively analyzed using questionnaires including an examination. RESULTS: The purely virtual implementation of head and neck ultrasound courses proved to be a viable alternative to the conventional course format, with a high level of acceptance among the participants. The lack of practice among the participants remains a relevant criticism. CONCLUSION: A more dominant role of web-based and remote ultrasound training is likely and should be considered as an alternative depending on existing conditions. Nevertheless, acquisition of practical sonographic skills remains a major hurdle if courses are purely digital.

[Providing practical skills in curricular teaching-effect of SkillsLab and flipped classroom]. / Vermittlung praktischer Fähigkeiten in der curricularen Lehre ­ Effekt von SkillsLab und "flipped classroom".

BACKGROUND: In the course of the restructuring of medical studies, practical competencies are clearly defined as learning objectives for the first time. In order to make most effective use of the short attendance time available in otolaryngology, the aim of this study was to teach practical skills with the help of flipped classroom, digital teaching, and a newly established SkillsLab. MATERIALS AND METHODS: During their ENT internship, two groups of students-group A = 93 students (male n = 42, female n = 51) and group B = 113 students (male n = 42, female n = 71)-first worked through material provided online, which explained the individual examinations. This was followed by face-to-face teaching, which consisted of observation and practical exercise of the different examination techniques. While group A practiced on each other or on dummies, group B used structured workstations in the ENT SkillsLab, which was newly built for this purpose. The effects on motivation and subjective competence were measured using a questionnaire developed for this study. RESULTS: After working through the online material, both groups showed a high level of motivation and competence. On the day of face-to-face teaching, there was a gain in motivation and competence, which was statistically significant only in the SkillsLab group (p < 0.001). Although the SkillsLab group was inferior in terms of its subjective competence at the beginning, it was superior to the other group after the face-to-face teaching. CONCLUSION: Combination of digitized teaching in the flipped classroom with structured workstations in the setting of a SkillsLab enables more effective teaching of practical skills, which was reflected by increases in motivation and subjective competence in group B. In particular, the presentation of all collected findings on monitors allows verification of learning success and stimulates discussion.

Comparing linear and non-linear models to estimate the appropriate cochlear implant electrode array length-are current methods precise enough?

PURPOSE: In cochlear implantation with flexible lateral wall electrode arrays, a cochlear coverage (CC) range between 70% and 80% is considered ideal for optimal speech perception. To achieve this CC, the cochlear implant (CI) electrode array has to be chosen according to the individual cochlear duct length (CDL). Here, we mathematically analyzed the suitability of different flexible lateral wall electrode array lengths covering between 70% and 80% of the CDL. METHODS: In a retrospective cross-sectional study preoperative high-resolution computed tomography (HRCT) from patients undergoing cochlear implantation was investigated. The CDL was estimated using an otosurgical planning software and the CI electrode array lengths covering 70-80% of the CDL was calculated using (i) linear and (ii) non-linear models. RESULTS: The analysis of 120 HRCT data sets showed significantly different model-dependent CDL. Significant differences between the CC of 70% assessed from linear and non-linear models (mean difference: 2.5 mm, p < 0.001) and the CC of 80% assessed from linear and non-linear models (mean difference: 1.5 mm, p < 0.001) were found. In up to 25% of the patients none of the existing flexible lateral wall electrode arrays fit into this range. In 59 cases (49,2%) the models did not agree on the suitable electrode arrays. CONCLUSIONS: The CC varies depending on the underlying CDL approximation, which critically influences electrode array choice. Based on the literature, we hypothesize that the non-linear method systematically overestimates the CC and may lead to rather too short electrode array choices. Future studies need to assess the accuracy of the individual mathematical models.

Performing Repeated Intraoperative Impedance Telemetry Measurements during Cochlear Implantation.

Impedance measurements are routinely performed during cochlear implantation (CI) after finalized electrode insertion. They may allow conclusions on the electrode's and implant's function. In the postoperative setting, the analysis of impedance changes enables the identification of scarring or inflammation processes around the electrode. Recent studies report associations between impedance telemetry and the site of stimulation. Consequently, repeated impedance measurements during cochlear implant electrode insertion may enable objective feedback on whether the electrode is positioned inside the perilymph or outside the inner ear. With the presented novel method, impedances can be measured in real-time during cochlear implantation. This protocol systematically explains how to perform repeated impedance recordings during CI surgery. These repeated measurements are challenging since they depend on multiple intraoperative methodological factors starting with the draping of the patient. Thus, for successful recordings, a standardized procedure is mandatory. In this article, we comprehensively illustrate the system setup and procedure of performing intraoperative measurements during CI surgery.

Accuracy of Preoperative Cochlear Duct Length Estimation and Angular Insertion Depth Prediction.

OBJECTIVE: In cochlear implantation with flexible lateral wall electrodes, a cochlear coverage of 70% to 80% is assumed to yield an optimal speech perception. Therefore, fitting the cochlear implant (CI) to the patient's individual anatomy has gained importance in recent years. For these reasons, the optimal angular insertion depth (AID) has to be calculated before cochlear implantation. One CI manufacturer offers a software that allows to visualize the AID of different electrode arrays. Here, it is hypothesized that these preoperative AID models overestimate the postoperatively measured insertion angle. This study aims to investigate the agreement between preoperatively estimated and postoperatively measured AID. STUDY DESIGN: Retrospective cross-sectional study. SETTING: Single-center tertiary referral center. PATIENTS: Patients undergoing cochlear implantation. INTERVENTION: Preoperative and postoperative high-resolution computed tomography (HRCT). MAIN OUTCOME MEASURES: The cochlear duct length was estimated by determining cochlear parameters ( A value and B value), and the AID for the chosen electrode was (i) estimated by elliptic circular approximation by the software and (ii) measured manually postoperatively by detecting the electrode contacts after insertion. RESULTS: A total of 80 HRCT imaging data sets from 69 patients were analyzed. The mean preoperative AID estimation was 662.0° (standard deviation [SD], 61.5°), and the mean postoperatively measured AID was 583.9° (SD, 73.6°). In all cases (100%), preoperative AID estimation significantly overestimated the postoperative determined insertion angle (mean difference, 38.1°). A correcting factor of 5% on preoperative AID estimation dissolves these differences. CONCLUSIONS: The use of an electrode visualization tool may lead to shorter electrode array choices because of an overestimation of the insertion angle. Applying a correction factor of 0.95 on preoperative AID estimation is recommended.

[Health-related quality of life in chronic otitis media-measurement methods and their application in surgical therapy]. / Gesundheitsbezogene Lebensqualität bei der chronischen Otitis media ­ Messmethoden und deren Anwendung bei chirurgischen Therapien.

BACKGROUND: Chronic otitis media (COM) can lead to significant impairment of health-related quality of life (HRQoL) due to symptoms such as otorrhea, pain, hearing loss, tinnitus, or dizziness. A systematic assessment of HRQoL in COM is becoming increasingly important as it complements (semi-)objective outcome parameters in clinical practice and research. HRQoL is measured by means of patient-reported outcome measures (PROMs). There are two disease-specific validated PROMs available for COM in German-the Chronic Otitis Media Outcome Test (COMOT-15) and the Zurich Chronic Middle Ear Inventory (ZCMEI-21)-which have become increasingly popular in recent years. OBJECTIVE: The purpose of this narrative review is to present the current state of research on measuring HRQoL in COM before and after surgical procedures. RESULTS AND CONCLUSION: Hearing is the most important factor influencing HRQoL in COM. Surgical procedures usually result in a clinically relevant improvement in HRQoL in COM with or without cholesteatoma. However, if cholesteatoma is present, its extent does not correlate with HRQoL. While HRQoL plays a secondary role in establishment of the indication for surgical therapy in COM with cholesteatoma, it plays an important role in terms of relative surgical indications, e.g., a symptomatic open mastoid cavity after resection of the posterior canal wall. We encourage the regular use of disease-specific PROMs preoperatively as well as during follow-up to assess HRQoL in COM in individual patients, in research, and in the context of quality monitoring.

[Cochlear implantation - Adverse effects on the cochlea and the vestibular organ]. / Cochlea-Implantation.

Cochlear implantation is the treatment of choice for patients with profound hearing loss and deafness. At the same time, inserting a cochlear implant (CI) leaves damage to the inner ear. The preservation of inner ear structure and function has become a central issue in CI surgery. The reasons for this are i) electroacoustic stimulation (EAS), i.e., the option of joint stimulation by a hearing aid and a CI; ii) an improved audiologic outcome in electric-only stimulation; iii) the preservation of structures and residual hearing for potential future therapy options; and iv) the avoidance of side effects, such as vertigo. The exact mechanisms that determine the extent of damage to the inner ear and which factors contribute to preservation of residual hearing are not yet fully understood. In addition to the surgical technique, electrode selection may play a role. This article provides an overview of what is known about the direct and indirect adverse effects of cochlear implantation on the inner ear, of the methods available to monitor inner ear function during cochlear implantation, and of the focus of future research on preservation of inner ear structure and function.

Internal auditory canal volume in normal and malformed inner ears.

PURPOSE: A narrow bony internal auditory canal (IAC) may be associated with a hypoplastic cochlear nerve and poorer hearing performances after cochlear implantation. However, definitions for a narrow IAC vary widely and commonly, qualitative grading or two-dimensional measures are used to characterize a narrow IAC. We aimed to refine the definition of a narrow IAC by determining IAC volume in both control patients and patients with inner ear malformations (IEMs). METHODS: In this multicentric study, we included high-resolution CT (HRCT) scans of 128 temporal bones (85 with IEMs: cochlear aplasia, n = 11; common cavity, n = 2; cochlear hypoplasia type, n = 19; incomplete partition type I/III, n = 8/8; Mondini malformation, n = 16; enlarged vestibular aqueduct syndrome, n = 19; 45 controls). The IAC diameter was measured in the axial plane and the IAC volume was measured by semi-automatic segmentation and three-dimensional reconstruction. RESULTS: In controls, the mean IAC diameter was 5.5 mm (SD 1.1 mm) and the mean IAC volume was 175.3 mm3 (SD 52.6 mm3). Statistically significant differences in IAC volumes were found in cochlear aplasia (68.3 mm3, p < 0.0001), IPI (107.4 mm3, p = 0.04), and IPIII (277.5 mm3, p = 0.0004 mm3). Inter-rater reliability was higher in IAC volume than in IAC diameter (intraclass correlation coefficient 0.92 vs. 0.77). CONCLUSIONS: Volumetric measurement of IAC in cases of IEMs reduces measurement variability and may add to classifying IEMs. Since a hypoplastic IAC can be associated with a hypoplastic cochlear nerve and sensorineural hearing loss, radiologic assessment of the IAC is crucial in patients with severe sensorineural hearing loss undergoing cochlear implantation.