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The BONEBRIDGE is a partially implantable, transcutaneous bone conduction device that can be used to treat conductive or mixed mild-to-moderate hearing loss in patients who do not attain sufficient improvement from conventional hearing aids. The following case report describes sequential bilateral BONEBRIDGE implantation in a 25-year-old patient with achondroplasia and bilateral mixed-hearing loss with a significant sensorineural component in the setting of chronic suppurative otitis media. Although the patient did not meet the approved BONEBRIDGE criteria, implantation was successful with improvements in audiological outcomes and self-reported quality of life. There were no reported complications at 5-years post-implantation.

Learning to use a surgical microscope is a fundamental step in otolaryngology training; however, there is currently no objective method to teach or assess this skill. Tympanostomy tube placement is a common otologic procedure that requires skilled use of a surgical microscope. This study was designed to (1) implement metrics capable of evaluating microscope use and (2) establish construct validity. This was a prospective cohort study. Eight otolaryngology trainees and three otolaryngology experts were asked to use a microscope to insert a tympanostomy tube into a cadaveric myringotomy in a standardized setting. Microscope movements were tracked in a three-dimensional space, and tracking metrics were applied to the data. The procedure was video-recorded and then analyzed by blinded experts using operational metrics. Results from both groups were compared, and discriminatory metrics were determined. The following tracking metrics were identified as discriminatory between the trainee and expert groups: total completion time, operation time, still time, and jitter (movement perturbation). Many operational metrics were found to be discriminatory between the two groups, including several positioning metrics, optical metrics, and procedural metrics. Performance metrics were implemented, and construct validity was established for a subset of the proposed metrics by discriminating between expert and novice participants. These discriminatory metrics could form the basis of an automated system for providing feedback to residents during training while using a myringotomy surgical simulator. Additionally, these metrics may be useful in guiding a standardized teaching and evaluation methodology for training in the use of surgical microscopes.

Hypothesis Measuring the length of the basilar membrane (BM) in the cochlear hook region will result in improved accuracy of cochlear duct length (CDL) measurements. Background Cochlear implant pitch mapping is generally performed in a patient independent approach, which has been shown to result in place-pitch mismatches. In order to customize cochlear implant pitch maps, accurate CDL measurements must be obtained. CDL measurements generally begin at the center of the round window (RW) and ignore the basal-most portion of the BM in the hook region. Measuring the size and morphology of the BM in the hook region can improve CDL measurements and our understanding of cochlear tonotopy. Methods Ten cadaveric human cochleae underwent synchrotron radiation phase-contrast imaging. The length of the BM through the hook region and CDL were measured. Two different CDL measurements were obtained for each sample, with starting points at the center of the RW (CDLRW) and the basal-most tip of the BM (CDLHR). Regression analysis was performed to relate CDLRW to CDLHR. A three-dimensional polynomial model was determined to describe the average BM hook region morphology. Results The mean CDLRW value was 33.03 ± 1.62 mm, and the mean CDLHR value was 34.68 ± 1.72 mm. The following relationship was determined between CDLRW and CDLHR: CDLHR = 1.06(CDLRW)-0.26 (R2 = 0.99). Conclusion The length and morphology of the hook region was determined. Current measurements underestimate CDL in the hook region and can be corrected using the results herein.

The human cochlea transforms sound waves into electrical signals in the acoustic nerve fibers with high acuity. This transformation occurs via vibrating anisotropic membranes (basilar and tectorial membranes) and frequency-specific hair cell receptors. Frequency-positions can be mapped within the cochlea to create a tonotopic chart which fits an almost-exponential function with lowest frequencies positioned apically and highest frequencies positioned at the cochlear base (Bekesy 1960, Greenwood 1961). To date, models of frequency positions have been based on a two-dimensional analysis with inaccurate representations of the cochlear hook region. In the present study, the first three-dimensional frequency analysis of the cochlea using dendritic mapping to obtain accurate tonotopic maps of the human basilar membrane/organ of Corti and the spiral ganglion was performed. A novel imaging technique, synchrotron radiation phase-contrast imaging, was used and a spiral ganglion frequency function was estimated by nonlinear least squares fitting a Greenwood-like function (F = A (10ax − K)) to the data. The three-dimensional tonotopic data presented herein has large implications for validating electrode position and creating customized frequency maps for cochlear implant recipients.

Human spiral ganglion (HSG) cell bodies located in the bony cochlea depend on a rich vascular supply to maintain excitability. These neurons are targeted by cochlear implantation (CI) to treat deafness, and their viability is critical to ensure successful clinical outcomes. The blood supply of the HSG is difficult to study due to its helical structure and encasement in hard bone. The objective of this study was to present the first three-dimensional (3D) reconstruction and analysis of the HSG blood supply using synchrotron radiation phase-contrast imaging (SR-PCI) in combination with histological analyses of archival human cochlear sections. Twenty-six human temporal bones underwent SR-PCI. Data were processed using volume-rendering software, and a representative three-dimensional (3D) model was created to allow visualization of the vascular anatomy. Histologic analysis was used to verify the segmentations. Results revealed that the HSG is supplied by radial vascular twigs which are separate from the rest of the inner ear and encased in bone. Unlike with most organs, the arteries and veins in the human cochlea do not follow the same conduits. There is a dual venous outflow and a modiolar arterial supply. This organization may explain why the HSG may endure even in cases of advanced cochlear pathology. These authors share last authorship: Hanif M. Ladak, Sumit K. Agrawal and Helge Rask-Andersen.

Background Trainees in Otolaryngology–Head and Neck Surgery must gain proficiency in a variety of challenging temporal bone surgical techniques. Traditional teaching has relied on the use of cadavers; however, this method is resource-intensive and does not allow for repeated practice. Virtual reality surgical training is a growing field that is increasingly being adopted in Otolaryngology. CardinalSim is a virtual reality temporal bone surgical simulator that offers a high-quality, inexpensive adjunct to traditional teaching methods. The objective of this study was to establish the face and content validity of CardinalSim through a national study. Methods Otolaryngologists and resident trainees from across Canada were recruited to evaluate CardinalSim. Ethics approval and informed consent was obtained. A face and content validity questionnaire with questions categorized into 13 domains was distributed to participants following simulator use. Descriptive statistics were used to describe questionnaire results, and either Chi-square or Fishers exact tests were used to compare responses between junior residents, senior residents, and practising surgeons. Results Sixty-two participants from thirteen different Otolaryngology–Head and Neck Surgery programs were included in the study (32 practicing surgeons; 30 resident trainees). Face validity was achieved for 5 out of 7 domains, while content validity was achieved for 5 out of 6 domains. Significant differences between groups (p-value of p = 0.002) and two content validity domains (teaching drilling technique, p = 0.011 and overall teaching utility, p = 0.006). The assessment scores, global rating scores, and overall attitudes towards CardinalSim, were universally positive. Open-ended questions identified limitations of the simulator. Conclusion CardinalSim met acceptable criteria for face and content validity. This temporal bone virtual reality surgical simulation platform may enhance surgical training and be suitable for patient-specific surgical rehearsal for practicing Otolaryngologists.

Hypothesis To characterize anatomical measurements and shape variation of the facial nerve within the temporal bone, and to create statistical shape models (SSMs) to enhance knowledge of temporal bone anatomy and aid in automated segmentation. Background The facial nerve is a fundamental structure in otologic surgery, and detailed anatomic knowledge with surgical experience are needed to avoid its iatrogenic injury. Trainees can use simulators to practice surgical techniques, however manual segmentation required to develop simulations can be time consuming. Consequently, automated segmentation algorithms have been developed that use atlas registration, SSMs, and deep learning. Methods Forty cadaveric temporal bones were evaluated using three dimensional microCT (μCT) scans. The image sets were aligned using rigid fiducial registration, and the facial nerve canals were segmented and analyzed. Detailed measurements were performed along the various sections of the nerve. Shape variability was then studied using two SSMs: one involving principal component analysis (PCA) and a second using the Statismo framework. Results Measurements of the nerve canal revealed mean diameters and lengths of the labyrinthine, tympanic, and mastoid segments. The landmark PCA analysis demonstrated significant shape variation along one mode at the distal tympanic segment, and along three modes at the distal mastoid segment. The Statismo shape model was consistent with this analysis, emphasizing the variability at the mastoid segment. The models were made publicly available to aid in future research and foster collaborative work. Conclusion The facial nerve exhibited statistical variation within the temporal bone. The models used form a framework for automated facial nerve segmentation and simulation for trainees.

Objective To present surgical and audiometric outcomes of patients implanted with an active transcutaneous bone conduction implant following the novel middle fossa surgical approach with self-drilling screws. Study design Retrospective review. Setting Tertiary care center. Patients Thirty-seven adults with either conductive or mixed hearing loss that met indications for an active transcutaneous bone conduction implant were consecutively implanted from April, 2013 to May, 2018. Intervention Unilateral middle fossa implantation of an active transcutaneous bone conduction implant. Main outcome measures Patient charts were reviewed for surgical outcomes and complications over the 6-year period. Preoperative air conduction, preoperative bone conduction, and 3-month postoperative aided thresholds were recorded. Speech perception was assessed using CNC words and AzBio sentences. Pure-tone averages (PTAs; measured at 0.5, 1.0, 2.0 and 3.0 kHz), air-bone gap, and functional gain were calculated. Results Mean air conduction and bone conduction PTAs (±standard deviation) of the implanted ear were 66.8 dB (±14.9 dB) and 21.9 dB (±14.0 dB), respectively. Mean aided PTA was 26.5 dB (± 8.5 dB). The average functional gain was 40.3 dB (±19.0 dB). Favorable speech perception outcomes were observed. No complications or instances of revision surgery were reported, with a mean follow-up time of 32 months (range, 9-71 mo). Conclusions This is the first paper to describe outcomes of patients implanted with an active transcutaneous bone conduction implant via the middle fossa with self-drilling screws. Favorable surgical outcomes were observed with a follow-up of up to 6 years.

Hypothesis Evaluating the accuracy of cochlear duct length (CDL) measurements from a published three-dimensional (3D) analytical cochlear model using Synchrotron Radiation Phase-Contrast Imaging (SR-PCI) data will help determine its clinical applicability and allow for model adjustments to increase accuracy. Background Accurate CDL determination can aid in cochlear implant sizing for full coverage and frequency map programming, which has the potential to improve hearing outcomes in patients. To overcome problems with the currently available techniques for CDL determination, a novel 3D analytical cochlear model, dependent on four basal turn distances, was proposed in the literature. Methods SR-PCI data from 11 cadaveric human cochleae were used to obtain reference measurements. CDL values generated by the analytical cochlear model were evaluated in two conditions: when the number of cochlear turns (NCT) were automatically predicted based on the four input distances, and when the NCT were manually specified based on SR-PCI data. Results When the analytical cochlear model automatically predicted the NCT, the mean absolute error was 2.6 ± 1.6 mm, with only 27% (3/11) of the samples having an error in the clinically acceptable range of ±1.5 mm. When the NCT were manually specified based on SR-PCI data, the mean absolute error was reduced to 1.0 ± 0.6 mm, with 73% (8/11) of the samples having a clinically acceptable error. Conclusion The 3D analytical cochlear model introduced in the literature is effective at modeling the 3D geometry of individual cochleae, however tuning in the NCT estimation is required.

Nasopharyngeal swabs currently remain the gold standard for COVID-19 sample collection. A surge in testing volume has resulted in a large number of health care workers who are unfamiliar with nasal anatomy performing this test, which can lead to improper collection practices culminating in false-negative results and complications. Therefore, we aimed to assess the accuracy and educational potential of a realistic 3D-printed nasal swab simulator to expedite health care workers' skill acquisition.Prospective pre-post interventional study.A nasal swab task trainer (NSTT) was developed to scale from computed tomography data with a deviated septum. Frontline workers at COVID-19 testing sites in Ontario, Canada, were recruited to use the NSTT for nasopharyngeal swab training. Integrated video recording capability allowed participants to self-evaluate procedure accuracy. A five-point Likert scale was collected regarding the NSTT's educational value and procedural fidelity.Sixty-two frontline workers included in the study were primarily registered nurses (52%) or paramedics (16%). Following simulator use, self-assessed accuracy improved in 77% of all participants and 100% of participants who expressed low confidence before training. Ninety-four percent reported that the NSTT provided a complete educational experience, and 82% regarded the system as a more effective training approach than what is currently available. Eighty-one indicated that the simulator should be used at all COVID-19 testing sites, with 77% stating province-wide implementation was warranted.The nasal swab task trainer is an effective educational tool that appears well-suited for improved skill acquisition in COVID-19 testing and may be useful for training other nasal swab applications.3 Laryngoscope, 2022.

Virtual reality simulation has gained prominence as a valuable surgical rehearsal and education tool in neurosurgery. Approaches to the internal auditory canal, cerebellopontine angle, and ventral brainstem region using the middle cranial fossa are not well explored by simulation.We hope to contribute to this paucity in simulation tools devoted to the lateral skull base, specifically the middle cranial fossa approach.Eight high-resolution microcomputed tomography scans of human cadavers were used as volumetric data sets to construct a high-fidelity visual and haptic rendering of the middle cranial fossa using CardinalSim software. Critical neurovascular structures related to this region of the skull base were segmented and incorporated into the modules.The virtual models illustrate the 3-dimensional anatomic relationships of neurovascular structures in the middle cranial fossa and allow a realistic interactive drilling environment. This is facilitated by the ability to render bone opaque or transparent to reveal the proximity to critical anatomy allowing for practice of the virtual dissection in a graduated fashion.We have developed a virtual library of middle cranial fossa approach models, which integrate relevant neurovascular structures with aims to improve surgical training and education. A ready extension is the potential for patient-specific application and pathology.

Objective Meniere's disease (MD) is a clinical disorder that often provides challenges in diagnosis and management. High-quality evidence to guide care providers is sparse, which can result in significant practice variations. Quality indicators (QIs) are one method that can be used to standardize and measure accepted care practices to improve healthcare quality and patient outcomes. Here, we developed practical, high-yield QIs that serve to measure and inform the quality of care provided to patients with MD. Study design Modified RAND Corporation University of California, Los Angeles appropriateness methodology for QI development. Setting Multicenter nine-member expert panel. Patients NA. Interventions NA. Main outcome measure Final QIs deemed appropriate measures of quality care with agreement by the expert panel. Results Twenty-seven candidate indicators were identified after literature review. After the first round of evaluations, the panel agreed on three candidate indicators as appropriate QIs. A subsequent expert panel meeting provided a platform to discuss disagreements. Two agreed-upon QIs were revised during this discussion before final evaluations. The expert panel ultimately agreed upon five QIs as appropriate measures of high-quality care after completing final evaluations and reviewing updated literature. The five quality indicators measure audiometric documentation, minimization of electrocochleography, use of intratympanic dexamethasone, use of intratympanic gentamycin, and rate of labyrinthectomy/vestibular neurectomy in refractory MD patient. Conclusions This study proposes five QIs that cover key aspects of care for MD, such as accurate diagnosis and management options including initial destructive therapies. These QIs can serve multiple purposes, the most important of which is to galvanize quality improvement initiatives.

Otosclerosis is a bone disorder of the otic capsule and common form of late-onset hearing impairment. Considered a complex disease, little is known about its pathogenesis. Over the past 20 years, ten autosomal dominant loci (OTSC1-10) have been mapped but no genes identified. Herein, we map a new OTSC locus to a 9.96 Mb region within the FOX gene cluster on 16q24.1 and identify a 15 bp coding deletion in Forkhead Box L1 co-segregating with otosclerosis in a Caucasian family. Phenotype ranges from moderate to severe hearing loss resolved by stapedectomy, to profound sensorineural loss requiring a cochlear implant. Mutant FOXL1 is both transcribed and translated and correctly locates to the cell nucleus. However, the deletion of 5 residues in the C-terminus of mutant FOXL1 causes a complete loss of transcriptional activity due to loss of secondary (alpha helix) structure. FOXL1 (rs764026385) was identified in a second unrelated case on a shared background. We conclude that FOXL1 (rs764026385) is pathogenic and causes autosomal dominant otosclerosis and propose a key inhibitory role for wildtype Foxl1 in bone remodelling in the otic capsule. New insights into the molecular pathology of otosclerosis from this study provide molecular targets for non-invasive therapeutic interventions.

Objective: Cochlear implants are traditionally programmed to stimulate according to a generalized frequency map, where individual anatomic variability is not considered when selecting the centre frequency of stimulation of each implant electrode. However, high variability in cochlear size and spatial frequency distributions exist among individuals. Generalized cochlear implant frequency maps can result in large pitch perception errors and reduced hearing outcomes for cochlear implant recipients. The objective of this work was to develop an individualized frequency mapping technique for the human cochlea to allow for patient-specific cochlear implant stimulation. Methods: Ten cadaveric human cochleae were scanned using synchrotron radiation phase-contrast imaging (SR-PCI) combined with computed tomography (CT). For each cochlea, ground truth angle-frequency measurements were obtained in three-dimensions using the SR-PCI CT data. Using an approach designed to minimize perceptual error in frequency estimation, an individualized frequency function was determined to relate angular depth to frequency within the cochlea. Results: The individualized frequency mapping function significantly reduced pitch errors in comparison to the current gold standard generalized approach. Conclusion and Significance: This paper presents for the first time a cochlear frequency map which can be individualized using only the angular length of cochleae. This approach can be applied in the clinical setting and has the potential to revolutionize cochlear implant programming for patients worldwide.

Background Trainees in Otolaryngology–Head and Neck Surgery must gain proficiency in a variety of challenging temporal bone surgical techniques. Traditional teaching has relied on the use of cadavers; however, this method is resource-intensive and does not allow for repeated practice. Virtual reality surgical training is a growing field that is increasingly being adopted in Otolaryngology. CardinalSim is a virtual reality temporal bone surgical simulator that offers a high-quality, inexpensive adjunct to traditional teaching methods. The objective of this study was to establish the face and content validity of CardinalSim through a national study. Methods Otolaryngologists and resident trainees from across Canada were recruited to evaluate CardinalSim. Ethics approval and informed consent was obtained. A face and content validity questionnaire with questions categorized into 13 domains was distributed to participants following simulator use. Descriptive statistics were used to describe questionnaire results, and either Chi-square or Fishers exact tests were used to compare responses between junior residents, senior residents, and practising surgeons. Results Sixty-two participants from thirteen different Otolaryngology–Head and Neck Surgery programs were included in the study (32 practicing surgeons; 30 resident trainees). Face validity was achieved for 5 out of 7 domains, while content validity was achieved for 5 out of 6 domains. Significant differences between groups (p-value of

Benign paroxysmal positional vertigo is the most common etiology of peripheral vertigo and is caused by the hydrodynamic influence from free-floating canaliths. Any of the 3 semicircular canals can be involved, but posterior canal BPPV is the predominant subtype. The condition is diagnosed clinically, and the preponderance of cases resolve spontaneously or are amenable to particle-repositioning maneuvers. A small subset of patients experience intractable symptoms for which surgical intervention can be considered. Transmastoid posterior canal occlusion surgery has been demonstrated to be a safe and curative procedure insofar as it can eradicate vertiginous symptoms while preserving auditory function.

Incus necrosis is a common complication following stapes surgery and is associated with impaired microcirculation. The objective of this study was to investigate the vascular anatomy of the human incus by using light microscopy, micro-computed tomography (micro-CT), and synchrotron phase-contrast imaging (SR-PCI) for a novel three-dimensional (3D) analysis of the middle ear, mucosal folds, major vascular pathways, and intraosseous vascular bone channels.One-hundred-and-fifty temporal bones from the Uppsala collection were analyzed under light microscopy. Twenty temporal bones underwent high-resolution micro-CT scanning, and an additional seven specimens underwent SR-PCI at the Canadian Lightsource in Saskatoon, Canada. One of these specimens was from an individual who had undergone stapes surgery. Data were processed with volume-rendering software to create 3D reconstructions using scalar opacity mapping for bone transparency, cropping, and soft tissue analyses.Micro-CT and SR-PCI with 3D rendering revealed the extensive vascular plexus within the un-decalcified incus bone communicating with the exterior surface. The relationship between the vessels, lenticular process, and incudostapedial joint were clearly observed. SR-PCI allowed for histologic-level detail while preserving the specimen and its 3D relationships.SR-PCI with 3D reconstructions confirmed the main vascular supply to the lenticular process along the intraosseous lenticular vessels. This is the first synchrotron analysis of a patient having undergone stapes surgery, and it suggests that incus necrosis associated with stapes surgery may be caused by a disruption of the lenticular blood flow induced by the prosthesis loop, and not by strangulation of mucosal vessels as has been previously described.

Objectives/hypothesis The objectives of the study were to present an institutional experience with device failures and cochlear reimplantation rates over a 30-year period and to perform a detailed literature review. Study design Retrospective institutional experience and literature review. Methods A review of cochlear implant failures over a period of 30 years, between January 1988 and March 2017, at a single institution was conducted. Cochlear implant failures were calculated based on manufacturer, type of failure, and overall failure rate. Survival analysis was performed using Kaplan-Meier curves. An electronic search of the PubMed, Web of Science, and EMBASE databases revealed 24 articles on the topic of cochlear device failure. Data on reimplantation and device failure rates were extracted from this literature review and analyzed. Results A total of 804 cochlear implantations were reviewed from three manufacturers. The institutional reimplantation rate was 2.9% compared to the pooled rate of 6.0% calculated from the literature review. Medical failures accounted for 0.5% of the overall failures, device failures accounted for 1.6%, and inconclusive failures account for 0.7%. Survival analysis revealed a significant difference among manufacturers. An improved device failure rate was noted in the adult population (0.8%) as compared to the pediatric population (2.8%). Conclusions This 30-year review represents one of the longest series in the literature examining reimplantation, device failure, and medical failure rates. Cochlear implant survival varied by manufacturer and was significantly better in adult compared to pediatric patients. Level of evidence NA Laryngoscope, 130:782-789, 2020.

Objective To three-dimensionally reconstruct Rosenthal's canal (RC) housing the human spiral ganglion (SG) using synchrotron radiation phase-contrast imaging (SR-PCI). Straight cochlear implant electrode arrays were inserted to better comprehend the electro-cochlear interface in cochlear implantation (CI). Design SR-PCI was used to reconstruct the human cochlea with and without cadaveric CI. Twenty-eight cochleae were volume rendered, of which 12 underwent cadaveric CI with a straight electrode via the round window (RW). Data were input into the 3D Slicer software program and anatomical structures were modeled using a threshold paint tool. Results The human RC and SG were reproduced three-dimensionally with artefact-free imaging of electrode arrays. The anatomy of the SG and its relationship to the sensory organ (Corti) and soft and bony structures were assessed. Conclusions SR-PCI and computer-based three-dimensional reconstructions demonstrated the relationships among implanted electrodes, angular insertion depths, and the SG for the first time in intact, unstained, and nondecalcified specimens. This information can be used to assess stimulation strategies and future electrode designs, as well as create place-frequency maps of the SG for optimal stimulation strategies of the human auditory nerve in CI.

OBJECTIVES To demonstrate that synchrotron radiation phase-contrast imaging (SR-PCI) can be used to visualize the intrascalar structures in implanted human cochleae and to find the optimal combination of the parameters object-to-detector distance (ODD) and beam energy (E) for visualization. MATERIALS AND METHODS Three cadaveric implanted human temporal bones underwent SR-PCI with varying combinations of parameters ODD (3, 2 and 1 m) and E (47, 60 and 72 keV). All images were then reconstructed to a three-dimensional (3D) stack of slices. The acquired 3D images were compared using contrast-to-noise ratios (CNRs) of the basilar membrane ( CNRBM ) and the electrode array (CNRE ) and the standard deviation of the beam streaks ( σS ). Postprocessing calculations were performed using Matlab (Version 2017b, MathWorks Inc., Natick, MA, U.S.A.) with a standard significance level p < 0.05 to determine the most optimal combination of parameters. RESULTS SR-PCI with computed tomography reconstruction provided good visualization of the anatomical features of the implanted cochleae, specifically the exact location of the electrode with respect to the BM. A single-factor ANOVA revealed a significant difference of variance for both CNRE and CNRBM , but failed to show significance for σS . A two-sample t-test failed to show any significant difference between CNRE columns of (3 m, 72 keV) and (2 m, 60 keV). The CNRBM was significantly different only at two pairs of columns, when (1 m, 72 keV) was compared against (2 m, 72 keV) and (3 m, 72 keV). CONCLUSIONS The results of this study show that SR-PCI is a viable method to visualize implanted human cochleae. SR-PCI is less invasive, less labour intensive and is associated with a much lower acquisition time compared to other methods for postimplantation imaging in humans, such as histological sectioning. We found that the optimal combination of E and ODD parameters was 72 keV and 2 m, respectively. These parameters resulted in high-contrast images of the electrode as well as all internal structures of the cochleae. LAY DESCRIPTION Cochlear implants (CI) are currently the preferred method of treatment for hearing loss. Cochlear implantation surgery involves placement of a metallic, wire-shaped electrode inside the cochlea, the main organ of the human hearing system. Knowledge of the exact location of the electrode after implantation is beneficial in improving the extent of restored hearing. Common clinical imaging modalities such as computed-tomography (CT) are not ideal for providing such information, due to lack of resolution and streaking caused by the metallic electrode. Recent studies have developed algorithms to extract the electrode location from clinical computed-tomography images and have been validated using histology or micro computed-tomography (micro-CT). Synchrotron radiation phase contrast imaging (SR-PCI) is a high-resolution imaging technique used to visualize small structures in three dimensions. Recently, SR-PCI has been shown to be an alternative to histology or micro-CT for imaging the human cochlea. However, it has not been optimized for imaging implanted human cochleae. The main objective of the present work was to find the optimal organization of imaging parameters (i.e., object-to-detector distance and beam energy) for using SR-PCI to image implanted human cochleae. Three cadaveric human cochleae were imaged using five different combinations of imaging parameters at the Canadian Light Source Inc., Saskatoon, SK, Canada. The resulting images were compared both quantitatively and qualitatively. An optimal combination of parameters was found to produce high-contrast images of the both the CI electrode and all internal structures of the cochlea with minimal streaking. SR-PCI is therefore a viable alternative to histological or micro-CT studies for post-surgical imaging of implanted human cochleae.

Objectives Prussak's space (PS) is an intricate middle ear region which may play an essential role in the development of middle ear disease. The three-dimensional (3D) anatomy of the human PS and its drainage routes remain relatively unknown. Earlier studies have histologically analyzed PS, by micro-dissection and endoscopy. Here, we used synchrotron-radiation phase-contrast imaging (SR-PCI), 3D reconstructions, and modeling to study the framework of the human PS, including aeration pathways. It may lead to increased understanding of development of middle ear pathology. Design Nine human temporal bone specimens underwent in-line SR-PCI at the Canadian Light Source in Saskatoon, Saskatchewan, Canada. Data were processed with volume-rendering software to create 3D reconstructions using scalar opacity mapping and segmentations to visualize its walls in fixed, undecalcified human temporal bones. Results The PS was found to be an irregular, variably shaped chamber with different aeration systems. Three different drainage pathways were found: 1) via the posterior malleolar pouch of von Troltsch in seven of nine ears; 2) directly posterior-inferior into the mesotympanum medial to the posterior malleolar pouch in one ear; and 3) anteriorly in another. The posterior-inferior communications depended on the anatomy of the posterior malleolar fold. In one bilateral case, the aeration differed between the ears. Earlier descriptions of upper ventilation routes between the PS and the epitympanic spaces could not be substantiated. Conclusions The 3D anatomy of the membrane folds organizing the PS in humans was demonstrated for the first time using in-line SR-PCI. The PS was always aerated into the mesotympanum, suggesting its relative independence of attic ventilation. The impact of its various drainage routes on middle ear ventilation and disease were discussed.

Introduction Auditory brainstem responses (ABRs) offer a unique opportunity to assess the neural integrity of the peripheral auditory nervous system in individuals presenting with listening difficulties. ABRs are typically recorded and analyzed by an audiologist who manually measures the timing and quality of the waveforms. The interpretation of ABRs requires considerable experience and training, and inappropriate interpretation can lead to incorrect judgments about the integrity of the system. Machine learning (ML) techniques may be a suitable approach to automate ABR interpretation and reduce human error. Objectives The main objective of this paper was to identify a suitable ML technique to automate the analysis of ABR responses recorded as a part of the electrophysiological testing in the Auditory Processing Disorder clinical test battery. Methods ABR responses recorded during routine clinical assessment from 136 children being evaluated for auditory processing difficulties were analyzed using several common ML algorithms: Support Vector Machines (SVM), Random Forests (RF), Decision Trees (DT), Gradient Boosting (GB), Extreme Gradient Boosting (Xgboost), and Neural Networks (NN). A variety of signal feature extraction techniques were used to extract features from the ABR waveforms as inputs to the ML algorithms. Statistical significance testing and confusion matrices were used to identify the most robust model capable of accurately identifying neurological abnormalities present in ABRs. Results Clinically significant features in the time-frequency representation of the signal were identified. The ML model trained using the Xgboost algorithm was identified as the most robust model with an accuracy of 92% compared to other models. Conclusion The findings of the present study demonstrate that it is possible to develop accurate ML models to automate the process of analyzing ABR waveforms recorded at suprathreshold levels. There is currently no ML-based application to screen children with listening difficulties. Therefore, it is expected that this work will be translated into an evaluation tool that can be used by audiologists in the clinic. Furthermore, this work may aid future researchers in exploring ML paradigms to improve clinical test batteries used by audiologists in achieving accurate diagnoses.

The ossicular chain is a middle ear structure consisting of the small incus, malleus and stapes bones, which transmit tympanic membrane vibrations caused by sound to the inner ear. Despite being shown to be highly variable in shape, there are very few morphological studies of the ossicles. The objective of this study was to use a large sample of cadaveric ossicles to create a set of three-dimensional models and study their statistical variance. Thirty-three cadaveric temporal bone samples were scanned using micro-computed tomography (μCT) and segmented. Statistical shape models (SSMs) were then made for each ossicle to demonstrate the divergence of morphological features. Results revealed that ossicles were most likely to vary in overall size, but that more specific feature variability was found at the manubrium of the malleus, the long process and lenticular process of the incus, and the crura and footplate of the stapes. By analyzing samples as whole ossicular chains, it was revealed that when fixed at the malleus, changes along the chain resulted in a wide variety of final stapes positions. This is the first known study to create high-quality, three-dimensional SSMs of the human ossicles. This information can be used to guide otological surgical training and planning, inform ossicular prosthesis development, and assist with other ossicular studies and applications by improving automated segmentation algorithms. All models have been made publicly available.

Direct drive hearing devices, which deliver a signal directly to the middle ear by vibrating the tympanic membrane via a lens placed in contact with the umbo, are designed to provide an extension of audible bandwidth, but there are few studies of the effects of these devices on preference, speech intelligibility, and loudness. The current study is the first to compare aided speech understanding between narrow and extended bandwidth conditions for listeners with hearing loss while fitted with a direct drive hearing aid system. The study also explored the effect of bandwidth on loudness perception and investigated subjective preference for bandwidth. Fifteen adult hearing aid users with symmetrical sensorineural hearing loss participated in a prospective, within-subjects, randomized single-blind repeated-measures study. Participants wore the direct drive hearing aids for 4 to 15 weeks (average 6 weeks) prior to outcome measurement. Outcome measures were completed in various bandwidth conditions achieved by reducing the gain of the device above 5000 Hz or by filtering the stimuli. Aided detection thresholds provided evidence of amplification to 10000 Hz. A significant improvement was found in high-frequency consonant detection and recognition, as well as for speech in noise performance in the full versus narrow bandwidth conditions. Subjective loudness ratings increased with provision of the full bandwidth available; however, real-world trials showed most participants were able to wear the full bandwidth hearing aids with only small adjustments to the prescription method. The majority of participants had either no preference or a preference for the full bandwidth setting.

OBJECTIVE: To determine sound quality for extended bandwidth amplification using a direct drive hearing device. STUDY DESIGN: Prospective double-blind within-subjects repeated measures study. SETTING: University hearing research laboratories. PATIENTS: Fifteen experienced hearing aid users with symmetric mild-sloping-to-severe sensorineural hearing loss. INTERVENTIONS: Sound quality ratings of speech and music passages were obtained using the Multiple Stimulus with Hidden References and Anchors (MUSHRA) protocol after wearing a direct drive hearing aid for at least 4 weeks. Passages were processed to filter out low-frequency (below 123 and 313 Hz) and high-frequency (above 4455, 5583, 6987, and 10,869 Hz) energy. MAIN OUTCOME MEASURES: Comparison of sound quality ratings for speech and music between low and high-pass filter frequencies measured from 0 to 100, where 0 represents "bad" and 100 represents "excellent." RESULTS: Wider bandwidth stimuli received higher sound quality ratings compared with narrower bandwidth stimuli. Conditions with more low-frequency energy (full-band and 123 Hz cut-off) were rated as having higher sound quality. More low-frequency energy in the 123 Hz condition was rated as having higher sound versus the 313 Hz condition (mean difference: 11.2%, p = 0.001). Full-band conditions with more low- and high-frequency energy were higher than the other high-frequency cutoff conditions (mean difference range: 12.9-15%, p

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The temporal bone is a part of the lateral skull surface that contains organs responsible for hearing and balance. Mastering surgery of the temporal bone is challenging because of this complex and microscopic three-dimensional (3D) anatomy. Virtual reality (VR) surgical simulators have proven to be effective for surgical training. In this paper a fully automated method is proposed for segmenting multiple temporal-bone structures based on micro computed tomography (micro-CT) images for a realistic virtual environment. An automated segmentation pipeline is proposed based on a three-dimensional, fully convolutional neural network. The proposed balanced subsampling strategy creates balanced learning among the labels of multiple anatomical structures and reduces the class imbalance. The accuracy and speed of the proposed algorithm outperforms current manual and semi-automated segmentation techniques. The average Dice similarity scores for all temporal-bone structures was 88%. The proposed algorithm was validated on low-resolution CTs scanned by other centers with different scanner parameters than the ones used to create the algorithm. The presented fully automated segmentation algorithm creates 3D models of multiple structures of temporal-bone anatomy from micro- CT images with sufficient accuracy to be used in VR surgical training simulators.

Objective: To assess the performance of an active transcutaneous implantable-bone conduction device (TI-BCD), and to evaluate the benefit of device digital signal processing (DSP) features in challenging listening environments. Design: Participants were tested at 1- and 3-month post-activation of the TI-BCD. At each session, aided and unaided phoneme perception was assessed using the Ling-6 test. Speech reception thresholds (SRTs) and quality ratings of speech and music samples were collected in noisy and reverberant environments, with and without the DSP features. Self-assessment of the device performance was obtained using the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire. Study sample: Six adults with conductive or mixed hearing loss. Results: Average SRTs were 2.9 and 12.3 dB in low and high reverberation environments, respectively, which improved to −1.7 and 8.7 dB, respectively with the DSP features. In addition, speech quality ratings improved by 23 points with the DSP features when averaged across all environmental conditions. Improvement scores on APHAB scales revealed a statistically significant aided benefit. Conclusions: Noise and reverberation significantly impacted speech recognition performance and perceived sound quality. DSP features (directional microphone processing and adaptive noise reduction) significantly enhanced subjects’ performance in these challenging listening environments.

Background Despite significant anatomical variation amongst patients, cochlear implant frequency-mapping has traditionally followed a patient-independent approach. Basilar membrane (BM) length is required for patient-specific frequency-mapping, however cochlear duct length (CDL) measurements generally extend to the apical tip of the entire cochlea or have no clearly defined end-point. By characterizing the length between the end of the BM and the apical tip of the entire cochlea (helicotrema length), current CDL models can be corrected to obtain the appropriate BM length. Synchrotron radiation phase-contrast imaging has made this analysis possible due to the soft-tissue contrast through the entire cochlear apex. Methods Helicotrema linear length and helicotrema angular length measurements were performed on synchrotron radiation phase-contrast imaging data of 14 cadaveric human cochleae. On a sub-set of six samples, the CDL to the apical tip of the entire cochlea (CDLTIP) and the BM length (CDLBM) were determined. Regression analysis was performed to assess the relationship between CDLTIP and CDLBM. Results The mean helicotrema linear length and helicotrema angular length values were 1.6 ± 0.9 mm and 67.8 ± 37.9 degrees, respectively. Regression analysis revealed the following relationship between CDLTIP and CDLBM: CDLBM = 0.88(CDLTIP) + 3.71 (R2 = 0.995). Conclusion This is the first known study to characterize the length of the helicotrema in the context of CDL measurements. It was determined that the distance between the end of the BM and the tip of the entire cochlea is clinically consequential. A relationship was determined that can predict the BM length of an individual patient based on their respective CDL measured to the apical tip of the cochlea.