Development and Evaluation of a Reusable, Force Measuring Tool for the Robot-Assisted Insertion of Cochlear Implant Electrode Arrays.

OBJECTIVE: Limitations in human kinematics during cochlear implantation induce pressure transients and increased forces on intracochlear structures. Herein, we present a novel head-mounted surgical tool designed for the motorized insertion of cochlear implant electrode arrays. The tool integrates a force measurement feature to overcome the lack of haptic feedback in current robotic solutions. METHODS: Utilizing a prototype device, we compare force measurements with those exerted on intracochlear structures in a realistic temporal bone model. Furthermore, we test the tool on six temporal bone specimens in a surgical setting to assess its performance in various anatomies. RESULTS: Force measurements exhibit good agreement with intracochlear forces, offering significantly improved resolution over manual, tactile sensing. Successful electrode array insertions in six cadaver specimens affirmed the feasibility of tool setup, motorized insertion and tool removal in different anatomies. CONCLUSION: The tool allows the robot-assisted insertion of cochlear implant electrode arrays and offers valuable insights during the surgical procedure, demonstrating promise for application in clinical contexts. SIGNIFICANCE: This instrument has the potential to aid surgeons in achieving atraumatic placement of electrodes, consequently contributing to the improvement of hearing outcomes in cochlear implantation.

Electrocochleography in Cochlear Implant Recipients: Correlating Maximum Response With Residual Hearing.

OBJECTIVES: Electrocochleography (ECochG) is increasingly recognized as a biomarker for assessing inner ear function in cochlear implant patients. This study aimed to objectively determine intraoperative cochlear microphonic (CM) amplitude patterns and correlate them with residual hearing in cochlear implant recipients, addressing the limitations in current ECochG analysis that often depends on subjective visual assessment and overlook the intracochlear measurement location. DESIGN: In this prospective study, we investigated intraoperative pure-tone ECochG following complete electrode insertion in 31 patients. We used our previously published objective analysis method to determine the maximum CM amplitude and the associated electrode position for each electrode array. Using computed tomography, we identified electrode placement and determined the corresponding tonotopic frequency using Greenwood's function. Based on this, we calculated the tonotopic shift, that is, the difference between the stimulation frequency and the estimated frequency of the electrode with the maximum CM amplitude. We evaluated the association between CM amplitude, tonotopic shift, and preoperative hearing thresholds using linear regression analysis. RESULTS: CM amplitudes showed high variance, with values ranging from -1.479 to 4.495 dBµV. We found a statistically significant negative correlation ( ) between maximum CM amplitudes and preoperative hearing thresholds. In addition, a significant association ( ) between the tonotopic shift and preoperative hearing thresholds was observed. Tonotopic shifts of the maximum CM amplitudes occurred predominantly toward the basal direction. CONCLUSIONS: The combination of objective signal analysis and the consideration of intracochlear measurement locations enhances the understanding of cochlear health and overcomes the obstacles of current ECochG analysis. We could show the link between intraoperative CM amplitudes, their spatial distributions, and preoperative hearing thresholds. Consequently, our findings enable automated analysis and bear the potential to enhance specificity of ECochG, reinforcing its role as an objective biomarker for cochlear health.

Three-dimensional infrared scanning: an enhanced approach for spatial registration of probes for neuroimaging.

Significance: Accurate spatial registration of probes (e.g., optodes and electrodes) for measurement of brain activity is a crucial aspect in many neuroimaging modalities. It may increase measurement precision and enable the transition from channel-based calculations to volumetric representations. Aim: This technical note evaluates the efficacy of a commercially available infrared three-dimensional (3D) scanner under actual experimental (or clinical) conditions and provides guidelines for its use. Method: We registered probe positions using an infrared 3D scanner and validated them against magnetic resonance imaging (MRI) scans on five volunteer participants. Results: Our analysis showed that with standard cap fixation, the average Euclidean distance of probe position among subjects could reach up to 43 mm, with an average distance of 15.25 mm [standard deviation (SD) = 8.0]. By contrast, the average distance between the infrared 3D scanner and the MRI-acquired positions was 5.69 mm (SD = 1.73), while the average difference between consecutive infrared 3D scans was 3.43 mm (SD = 1.62). The inter-optode distance, which was fixed at 30 mm, was measured as 29.28 mm (SD = 1.12) on the MRI and 29.43 mm (SD = 1.96) on infrared 3D scans. Our results demonstrate the high accuracy and reproducibility of the proposed spatial registration method, making it suitable for both functional near-infrared spectroscopy and electroencephalogram studies. Conclusions: The 3D infrared scanning technique for spatial registration of probes provides economic efficiency, simplicity, practicality, repeatability, and high accuracy, with potential benefits for a range of neuroimaging applications. We provide practical guidance on anonymization, labeling, and post-processing of acquired scans.

Survival from Rhino-Orbital-Cerebral Mucormycosis in SARS-CoV-2-Positive Diabetic Patients: Two Case Reports.

Introduction: Rhino-orbital-cerebral mucormycosis (ROCM) is a rare angioinvasive fungal infection known to be associated with high morbidity and over 50% mortality. ROCM is becoming more common due to an increase in predisposing immunocompromising comorbidities as well as COVID-19. Case Presentations: We report 2 cases - a 75-year-old woman with diabetes and a 39-year-old man with recurrent diabetic ketoacidosis. Both presented initially with acute sinonasal symptoms, were positive for SARS-CoV-2, and diagnosed with acute ROCM. Both underwent mutilating surgical therapy as well as high-dose amphotericin B treatment. With continued oral antifungal treatment, patient 1 showed stable symptoms despite radiographically increasing disease and died of urosepsis 5 months after first surgery. With posaconazole treatment, patient 2 recovered from the disease and showed no clinical sign of disease progression after 1 year. Conclusion: Despite the rarity of the disease, ROCM should be considered if the findings of clinical and radiological examination fit, so that a delay in treatment initiation can be avoided. As our both cases show, survival from ROCM is possible - albeit at a high cost.

Prevention of nostril lacerations in endonasal drilling procedures by use of a conventional protective ear speculum.

PURPOSE: Injuries of the nasal vestibular skin caused by the rotating burr shafts can represent a tedious complication following endonasal drilling and is experienced sooner or later by every rhino-surgeon. MATERIAL AND METHODS: To protect the nasal entrance from laceration by the free rotating drill shaft we position an otology speculum in the nasal entrance. The speculum is held in place by the scrub nurse during the critical phase of bone drilling. RESULTS: Following the introduction of the ear speculum protection, we successfully treated our dacryocystostamia procedures (n = 27) and median maxillectomia procedures (n = 6) without any further soft tissue erosions. DISCUSSION: Preventive measures for injuries by endonasal drilling procedures are not reported extensively in literature. This stands in contrast to the fact that these injuries are prone to cause significant suffering as amply described in the case of nostril laceration due to nasogastric intubation or nasogastric feeding tubes. CONCLUSION: The use of a readily available, reusable ear speculum in endonasal drill application eliminated the complication of nasal entrance lacerations throughout our institution, hitherto.

Uncovering Vulnerable Phases in Cochlear Implant Electrode Array Insertion: Insights from an In Vitro Model.

OBJECTIVES: The aim of this study is to improve our understanding of the mechanics involved in the insertion of lateral wall cochlear implant electrode arrays. DESIGN: A series of 30 insertion experiments were conducted by three experienced surgeons. The experiments were carried out in a previously validated artificial temporal bone model according to established soft surgery guidelines. The use of an in vitro setup enabled us to comprehensively evaluate relevant parameters, such as insertion force, intracochlear pressure, and exact electrode array position in a controlled and repeatable environment. RESULTS: Our findings reveal that strong intracochlear pressure transients are more frequently caused during the second half of the insertion, and that regrasping the electrode array is a significant factor in this phenomenon. For choosing an optimal insertion speed, we show that it is crucial to balance slow movement to limit intracochlear stress with short duration to limit tremor-induced pressure spikes, challenging the common assumption that a slower insertion is inherently better. Furthermore, we found that intracochlear stress is affected by the order of execution of postinsertion steps, namely sealing the round window and posterior tympanotomy with autologous tissue and routing of the excess cable into the mastoid cavity. Finally, surgeons' subjective estimates of physical parameters such as speed, smoothness, and resistance did not correlate with objectively assessed measures, highlighting that a thorough understanding of intracochlear mechanics is essential for an atraumatic implantation. CONCLUSION: The results presented in this article allow us to formulate evidence-based surgical recommendations that may ultimately help to improve surgical outcome and hearing preservation in cochlear implant patients.

Long-term night-to-night variability of sleep-disordered breathing using a radar-based home sleep apnea test: a prospective cohort study.

STUDY OBJECTIVES: Night-to-night variability of sleep-disordered breathing limits the diagnostic accuracy of a single measurement. Multiple recordings using a reliable, affordable method could reduce the uncertainty and avoid misdiagnosis, which could be possible with radar-based home sleep apnea testing (HSAT). METHODS: We recruited consecutive patients with suspected sleep-disordered breathing and performed contactless radar-based HSAT with automated scoring (Sleepiz One; Sleepiz AG, Zurich, Switzerland) over 10 nights. During the first night, patients were simultaneously measured with peripheral arterial tonometry. RESULTS: Twenty-four of the 28 included patients could achieve a minimum of 4 measurements. The failure rate was 16% (37 of 238 measurements). The apnea-hypopnea index (AHI) and oxygen desaturation index were consistently lower with radar-based HSAT compared with peripheral arterial tonometry. The variability of the AHI was considerable, with a standard error of measurement of 5.2 events/h (95% confidence interval [CI]: 4.6-5.7 events/h) and a minimal detectable difference of 14.4 events/h (95% CI: 12.7-15.9 events/h). Alcohol consumption partially accounted for the variability, with an AHI increase of 1.7 events/h (95% CI: 0.6-2.8 events/h) for each standard drink. Based on a single measurement, 17% of patients were misdiagnosed and 32% were misclassified for sleep-disordered breathing severity. After 5 measurements, the mean AHI of the measured nights stabilized with no evidence of substantial changes with additional measurements. CONCLUSIONS: Night-to-night variability is considerable and stable over 10 nights. HSAT using radar-based methods over multiple nights is feasible and well tolerated by patients. It could offer lower costs and allow for multiple-night testing to increase accuracy. However, validation and reducing the failure rate are necessary for implementation in the clinical routine. CLINICAL TRIAL REGISTRATION: Registry: ClinicalTrials.gov; Name: Recording of Multiple Nights Using a New Contactless Device (Sleepiz One Connect) in Obstructive Sleep Apnea; URL: https://clinicaltrials.gov/study/NCT05134402; Identifier: NCT05134402. CITATION: Tschopp S, Borner U, Caversaccio M, Tschopp K. Long-term night-to-night variability of sleep-disordered breathing using a radar-based home sleep apnea test: a prospective cohort study. J Clin Sleep Med. 2024;20(7):1079-1086.

Techniques of Endoscopic Ossiculoplasty.

The utilization of endoscopes in modern otology has evolved from diagnostic purposes to the development of exclusive endoscopic ear surgery. This technique offers a panoramic view of the middle ear and provides an optimal magnification of the oval window region, the stapes' suprastructure, and the footplate, allowing great precision in prosthesis positioning during ossiculoplasty (OPL). Various techniques for ossicular chain reconstruction have been described in the literature. Either autologous or synthetic materials can be used for reconstruction. The use of a patient's own tissue minimizes the risk of implant rejection or extrusion of the prosthesis through the tympanic membrane. On the other hand, synthetic materials like titanium are light and rigid and do not require time-consuming prosthesis remodeling. The main objective of this article is to present a comprehensive step-by-step guide that serves as a surgical manual for exclusive endoscopic OPL. This guide will explain various forms of OPL using synthetic and autologous materials. The goal is to provide a comprehensive understanding of the various surgical techniques and support the integration into clinical practice.

The human middle ear in motion: 3D visualization and quantification using dynamic synchrotron-based X-ray imaging.

The characterization of the vibrations of the middle ear ossicles during sound transmission is a focal point in clinical research. However, the small size of the structures, their micrometer-scale movement, and the deep-seated position of the middle ear within the temporal bone make these types of measurements extremely challenging. In this work, dynamic synchrotron-based X-ray phase-contrast microtomography is used on acoustically stimulated intact human ears, allowing for the three-dimensional visualization of entire human eardrums and ossicular chains in motion. A post-gating algorithm is used to temporally resolve the fast micromotions at 128 Hz, coupled with a high-throughput pipeline to process the large tomographic datasets. Seven ex-vivo fresh-frozen human temporal bones in healthy conditions are studied, and the rigid body motions of the ossicles are quantitatively delineated. Clinically relevant regions of the ossicular chain are tracked in 3D, and the amplitudes of their displacement are computed for two acoustic stimuli.

Impact of COVID-19 pandemic: increase in complicated upper respiratory tract infections requiring ENT surgery?

PURPOSE: This study investigates the impact of the COVID-19 pandemic on complicated upper respiratory tract infections requiring surgical intervention in a tertiary referral center. The aim is to understand the consequences of pandemic-related measures and their subsequent relaxation on the incidence and characteristics of upper respiratory tract infection-related complications. METHODS: Patients who underwent surgery as a complication of upper respiratory tract infections between December 2014 to February 2023 were included. Demographic information, surgical procedures, microbiological findings, and clinical outcomes were assessed and analyzed comparing pre-pandemic, pandemic and post-pandemic groups. RESULTS: 321 patients were enrolled, including 105 patients (32.7%) in the pediatric population. Comparison of pre-pandemic (n = 210), pandemic (n = 46) and post-pandemic periods (n = 65) revealed a statistically significant increase in complicated otologic infections requiring surgical intervention in the post-pandemic period compared to the pandemic period (p value = 0.03). No statistically significant differences in other surgical procedures or demographic parameters were observed. A statistically significant increase in urgent ear surgery in the pediatric population between the pandemic and the post-pandemic period (p value = 0.02) was observed. Beta-hemolytic group A streptococcal infections showed a statistically significant increase in the post-pandemic period compared with the pandemic period (p value = 0.02). CONCLUSIONS: Relaxation of COVID-19-related restrictions was associated with an increase of upper respiratory tract infection-related otologic infections requiring surgical intervention with an increasing rate of beta-hemolytic group A streptococcal infections. These findings highlight the importance of considering the impact of the pandemic on upper respiratory tract infection complications and adapting management strategies accordingly.

The acute vestibular syndrome: prevalence of new hearing loss and its diagnostic value.

OBJECTIVES: To assess the prevalence of new hearing losses in patients with acute vestibular syndrome (AVS) and to start to evaluate its diagnostic value for the differentiation between peripheral and central causes. DESIGN: We performed a cross-sectional prospective study in AVS patients presenting to our Emergency Department (ED) from February 2015 to November 2020. All patients received an MRI, Head-impulse test, Nystagmus test and Test of skew ('HINTS'), caloric testing and a pure-tone audiometry. RESULTS: We assessed 71 AVS patients, 17 of whom had a central and 54 a peripheral cause of dizziness. 12.7% had an objective hearing loss. 'HINTS' had an accuracy of 78.9% to diagnose stroke, whereas 'HINTS' plus audiometry 73.2%. 'HINTS' sensitivity was 82.4% and specificity 77.8% compared to 'HINTS' plus audiometry showing a sensitivity of 82.4% and specificity of 70.4%. The four patients with stroke and minor stroke had all central 'HINTS'. 55% of the patients did not perceive their new unilateral hearing loss. CONCLUSIONS: We found that almost one-eighth of the AVS patients had a new onset of hearing loss and only half had self-reported it. 'HINTS' plus audiometry proved to be less accurate to diagnose a central cause than 'HINTS' alone. Audiometry offered little diagnostic accuracy to detect strokes in the ED but might be useful to objectify a new hearing loss that was underestimated in the acute phase. Complete hearing loss should be considered a red flag, as three in four patients suffered from a central cause.

The value of saccade metrics and VOR gain in detecting a vestibular stroke.

OBJECTIVE: A normal video Head Impulse Test is the gold standard in the emergency department to rule-in patients with an acute vestibular syndrome and a stroke. We aimed to compare the diagnostic accuracy of vHIT metrics regarding the vestibulo-ocular reflex gain and the corrective saccades in detecting vestibular strokes. METHODS: Prospective cross-sectional study (convenience sample) of patients presenting with acute vestibular syndrome in the emergency department of a tertiary referral centre between February 2015 and May 2020. We screened 1677 patients and enrolled 76 patients fulfilling the inclusion criteria of acute vestibular syndrome. All patients underwent video head impulse test with automated and manual data analysis. A delayed MRI served as a gold standard for vestibular stroke confirmation. RESULTS: Out of 76 patients, 52 were diagnosed with acute unilateral vestibulopathy and 24 with vestibular strokes. The overall accuracy of detecting stroke with an automated vestibulo-ocular reflex gain was 86.8%, compared to 77.6% for cumulative saccade amplitude and automatic saccade mean peak velocity measured by an expert and 71% for cumulative saccade amplitude and saccade mean peak velocity measured automatically. Gain misclassified 13.1% of the patients as false positive or false negative, manual cumulative saccade amplitude and saccade mean peak velocity 22.3%, and automated cumulative saccade amplitude and saccade mean peak velocity 28.9% respectively. CONCLUSIONS: We found a better accuracy of video head impulse test for the diagnosis of vestibular strokes when using the vestibulo-ocular reflex gain than using saccade metrics. Nevertheless, saccades provide an additional and important information for video head impulse test evaluation. The automated saccade detection algorithm is not yet perfect compared to expert analysis, but it may become a valuable tool for future non-expert video head impulse test evaluations.

To detach or not to detach the umbo in type I tympanoplasty: functional results.

PURPOSE: To compare the audiological outcomes, tympanic membrane (TM) healing rates and complication rates in patients undergoing endoscopic underlay and over-under tympanoplasty type I (TTI). METHODS: The study includes 95 patients who underwent endoscopic TTI in the period between 2018 and 2023: 56% of the patients had the underlay technique and 41% had the over-under technique. Data regarding pre- and postoperative hearing, perforation characteristics, surgical procedures, graft types and complications were retrospectively analyzed. Audiometrical assessment included air conduction (AC) and bone conduction (BC) pure tone averages (PTA) and air-bone gap (ABG), pre- and postoperatively. RESULTS: Both underlay and over-under techniques significant improved AC PTA, with a mean ABG improvements of 5.9 dB and 7.2 dB, respectively. There was no significant difference in BC PTA between pre- and post-operative, indicating no inner ear damage in both techniques. The over-under technique showed a significantly higher TM closure rate (94.4%) compared to the underlay technique (80.6%). Complications were rare, with only one case of TM lateralization requiring revision surgery. CONCLUSIONS: Endoscopic TTI is an effective treatment in improving auditory function in chronic middle ear diseases. In our cohort, the detachment of the umbo does not negatively influence the postoperative hearing results and does not increase rate of complications. Moreover, the over-under technique demonstrates superior TM closure rates, making it a valuable option for specific cases. However, future prospective studies with larger sample sizes and longer term follow-up are needed to validate these findings and provide more comprehensive insights.

Wall Shear Stress and Pressure Fluctuations under Oscillating Stimulation in Helical Square Ducts with Cochlea-like Geometrical Curvature and Torsion.

Our study aims to provide basic insights on the impact of the spiral shape of the cochlea, i.e., of geometric torsion and curvature, on wall pressure and wall shear stress. We employed computational fluid dynamics in square duct models with curvature and torsion similar to those found in human cochleae. The results include wall pressures and wall shear stresses within the ducts under oscillating axial flow. Our findings indicate that the helical shape generates higher transverse wall shear stresses compared to exclusively curved or twisted ducts. The wall pressures and transverse wall shear stresses we found rise to amounts that may be physiologically relevant in the cochlea.Clinical relevance- The role of the spiral shape of the cochlea in hearing physiology remains, for a large part, elusive. For a better apprehension of hearing and its disorders, it is important to investigate the influence of geometric properties on biofluids motion and emerging phenomena in the cochlea.

Evaluating temporal bone column density for optimized bone conduction implant placement.

Introduction: An optimal placement of bone conduction implants can provide more efficient mechanical transmission to the cochlea if placed in regions with greater bone column density. The aim of this study was to test this hypothesis and to determine the clinical potential of preoperative bone column density assessment for optimal implant placement. Methods: Five complete cadaver heads were scanned with quantitative computed tomography imaging to create topographic maps of bone density based on the column density index (CODI). Laser Doppler vibrometry was used to measure cochlear promontory acceleration under bone conduction stimulation in different locations on the temporal bone, using a bone-anchored hearing aid transducer at frequencies ranging from 355 Hz to 10 kHz. Results: We found a statistically significant association between CODI levels and the accelerance of the cochlear promontory throughout the frequency spectrum, with an average increase of 0.6 dB per unit of CODI. The distance between the transducer and the cochlear promontory had no statistically significant effect on the overall spectrum. Discussion: We highlight the importance of bone column density in relation to the mechanical transmission efficiency of bone conduction implants. It may be worthwhile to consider column density in preoperative planning in clinical practice.

Hearing Results after Transmastoid Superior Semicircular Canal Plugging for Superior Semicircular Canal Dehiscence: A Meta-Analysis.

OBJECTIVE: The transmastoid plugging of a superior semicircular canal is considered a safe and effective technique for the management of superior semicircular canal dehiscence (SSCD). The aim of this meta-analysis is to assess the postoperative hearing outcomes after the transmastoid plugging of the superior semicircular canal. Search method and data sources: A systematic database search was performed on the following databases until 30 January 2023: MEDLINE, Embase, Cochrane Library, Web of Science, CINAHL, ICTRP, and clinicaltrials.gov. A systematic literature review and meta-analysis of the pooled data were conducted. We also included a consecutive case series with SCDS for those who underwent transmastoid plugging treatment at our clinic. RESULTS: We identified 643 citations and examined 358 full abstracts and 88 full manuscripts. A total of 16 studies were eligible for the systematic review and 11 studies for the meta-analysis. Furthermore, 159 ears (152 patients) were included. The postoperative mean air conduction threshold remained unchanged (mean difference, 2.89 dB; 95% CI: -0.05, 5.84 dB, p = 0.58), while the mean bone conduction threshold was significantly worse (mean difference, -3.53 dB; 95% CI, -6.1, -0.95 dB, p = 0.9). CONCLUSION: The transmastoid plugging technique for superior semicircular canal dehiscence syndrome, although minimally worsening the inner ear threshold, is a safe procedure in terms of hearing preservation and satisfactory symptom relief.

Vestibular function, subjective complaints, perceived disability in daily life, and sports activities in patients with cochlear implants performed during childhood: a prospective cross-section study.

BACKGROUND: Vestibular function (VF) in patients with cochlear implantation (CI) performed during childhood is underinvestigated. OBJECTIVE: To study VF in patients receiving CI during childhood. MATERIAL & METHODS: Sixty patients (22 females) from 7-34 years old, unilaterally (n = 21) and bilaterally (n = 39) implanted, were included. Deafness was congenital (n = 45), consequential to meningitis (n = 3), skull fracture (n = 1), perinatal CMV infection (n = 1), ototoxic drugs (n = 1), unknown etiology (n = 9). VF was measured between 1 to 22 years after implantation, including calorics, v-HIT, c-VEMPS. Dizziness handicap inventory (DHI), age at independent walking(IW), sport activities were also investigated. RESULTS: Nine CI-patients (15%) reported dizziness/vertigo either prior or months to years after surgery. Comparison between symptomatic (15%), asymptomatic (85%), uni-bilaterally CI-patients showed no significant difference on VF's impairment for calorics (p = .603) and v-HIT (p = 1). Symptoms were not related to vestibular impairment. Age at implantation (p = 0.956), uni- bilateral (p = .32), simultaneous versus sequential (p = .134) did not influence IW age. DHI showed a tendency for being symptomatic at higher implantation age. Interval between CI, IWage, current age between surgery and vestibular evaluation did not have a significant effect on symptomatology. CONCLUSION & SIGNIFICANCE: This first middle to long-term evaluation of the VF in CI-patients, implanted in childhood, pointed out that 85% of patients were asymptomatic, with a mean time of >10 years after surgery. Vestibular impairment and symptoms seem to be mainly due to the underlying inner ear's disease rather than surgery.

Comparison of auditory brainstem response and electrocochleography to assess the coupling efficiency of active middle ear implants.

Aim: This study aimed to compare the effectiveness of auditory brainstem response (ABR) and extracochlear electrocochleography (ECochG) in objectively evaluating the coupling efficiency of floating mass transducer (FMT) placement during active middle ear implant (AMEI) surgery. Methods: We enrolled 15 patients (mean age 58.5 ± 19.4 years) with mixed hearing loss who underwent AMEI implantation (seven ossicular chain and eight round window couplings). Before the surgical procedure, an audiogram was performed. We utilized a clinical measurement system to stimulate and record intraoperative ABR and ECochG recordings. The coupling efficiency of the VSB was evaluated through ECochG and ABR threshold measurements. Postoperatively, we conducted an audiogram and a vibrogram. Results: In all 15 patients, ABR threshold testing successfully determined intraoperative coupling efficiency, while ECochG was successful in only eight patients. In our cohort, ABR measurements were more practical, consistent, and robust than ECochG measurements. Coupling efficiency, calculated as the difference between vibrogram thresholds and postoperative bone conduction thresholds, was found to be more accurately predicted by ABR measurements (p = 0.016, R2 = 0.37) than ECochG measurements (p = 0.761, R2 = 0.02). We also found a non-significant trend toward better results with ossicular chain coupling compared to round window coupling. Conclusion: Our findings suggest that ABR measurements are more practical, robust, and consistent than ECochG measurements for determining coupling efficiency during FMT placement surgery. The use of ABR measurements can help to identify the optimal FMT placement, especially with round window coupling. Finally, we offer normative data for both techniques, which can aid other clinical centers in using intraoperative monitoring for AMEI placement.

First evaluation of an ovine training model for sialendoscopy.

Objective: Sialendoscopy is a minimally invasive diagnostic and therapeutic technique used in the treatment of various salivary gland diseases. To date, there are very few suitable training models other than the pig's head, which has been used at the European Sialendoscopy Training Center for 22 years. The goal of this study was to describe an ovine model for sialendoscopy training and compare the ovine model's to the human anatomy. We propose a step-by-step approach for sialendoscopy training using this ex-vivo model. Methods: The anatomy of the ovine salivary ducts and glands was assessed by magnetic resonance imaging using one fresh ovine head. Thereafter, the model was designed during dissection by an experienced sialendoscopist. The various steps were then validated during consecutive dissections using a Likert-scale questionnaire. Results: The full model was described in the form of a dissection guide and allowed reliable diagnostic sialendoscopy in 10/10 Stenson's and in 5/10 Wharton's ducts. Moreover, interventional sialendoscopy was simulated to provide a training model for the removal of sialoliths in the Stenson's duct. The human and ovine anatomy are quite similar allowing a training experience close to reality. Conclusion: We developed and evaluated an ovine model with the goal of improving training in diagnostic and interventional sialendoscopy. In particular, the Stenson's duct can be successfully prepared, probed and subjected to sialendoscopy. The realistic anatomical environment and excellent tissue quality created a life-like training experience for an experienced sialendoscopist. Further studies with beginners are necessary to validate this model as a training model. Level of Evidence: 4.