"Transcanal view" computed tomography reformat: Applications for transcanal endoscopic ear surgery.

PURPOSE: Transcanal endoscopic ear surgery (TEES) is an increasingly used surgical approach for otologic surgeries, but no en face preoperative imaging format currently exists. We aim to assess the utility of a transcanal high resolution computed tomography (HRCT) reformat suitable for TEES preoperative planning. MATERIALS AND METHODS: Preoperative HRCTs of patients with middle ear pathologies (cholesteatoma, otosclerosis, and glomus tympanicum) who underwent TEES were obtained. Axial image series were rotated and reformatted -90 or +90 degrees for left and right ear surgeries, respectively, where additional rotation along the left-right axis was performed to align the transcanal series with the plane of the external auditory canal. Quantitative measurements of middle ear structures were recorded. Consecutive transcanal reformatted sections were then reviewed to identify critical middle ear anatomy and pathology with corresponding TEES cases. RESULTS: The aforementioned methodology was used to create three transcanal view HRCTs. The mean left-right axis degree of rotation was 4.0 ± 2.2 degrees. In the cholesteatoma transcanal HRCT, areas of cholesteatoma involvement in middle ear compartments (e.g. epitympanum) and eroded ossicles were successfully identified in the corresponding case. In the otosclerosis transcanal HRCT, areas for potential otosclerotic involvement were visualized such as the round window as well as a low-hanging facial nerve. In the glomus tympanicum transcanal HRCT, the span of the glomus tympanicum was successfully visualized in addition to a high riding jugular bulb. CONCLUSION: A transcanal HRCT reformat may aid preoperative planning for middle ear pathologies. This novel reformat may help highlight patient-specific anatomy.

Adult Auditory Brainstem Implant Outcomes and Three-Dimensional Electrode Array Position on Computed Tomography.

OBJECTIVES: Factors contributing to auditory brainstem implant (ABI) outcomes are poorly understood. The aims of this study are to (1) characterize ABI electrode array position on postoperative imaging and (2) determine if variability in position is related to perceptual outcomes. DESIGN: Retrospective cohort study. Subjects were selected from the adult ABI recipient population at Massachusetts Eye and Ear. Postoperative three-dimensional (3D) computed tomography (CT) reconstruction of the head was used to measure ABI array position in 20 adult ABI recipients (17 with Neurofibromatosis Type 2 (NF2) and three non-NF2 recipients). Three-dimensional electrode array position was determined based on angles from the horizontal using posterior and lateral views and on distances between the proximal array tip superiorly from the basion (D1), laterally (D2P) and posteriorly (D2L) from the midline. Array position was correlated with perceptual data (in 15 of the 20 recipients who used their ABI). Perceptual data included the number of electrodes that provided auditory sensation, location and type of side effects, level of speech perception (from no sound to open-set word recognition of monosyllables) and the amount of charge required for auditory perception. RESULTS: Although the 3D orientation of the ABI array exhibited a variety of angles, all arrays were posteriorly tilted from the lateral view and most were medially tilted from the posterior view. ABI position relative to the basion from posterior showed mean distances of 1.71 ± 0.42 and 1.1 ± 0.29 cm for D1 and D2, respectively, and a mean D2 of 1.30 ± 0.45 cm from the lateral view. A strong linear negative correlation was found between the number of active electrodes and the distance of the proximal array tip laterally from the basion (D2P; rs = -0.73, p = 0.006) when measured in the posterior view. Although side effects were experienced in all recipients and varied in type and location across the array, electrodes in the middle part of the array tended to elicit auditory sensations while the proximal and distal tips of the array tended to elicit nonauditory side effects. Arrays with and without low charge thresholds appeared to generally overlap in position. However, the two recipients with the best (open-set) speech perception had low charge thresholds and had arrays that were tilted superiorly in the posterior view. CONCLUSION: ABI recipients with better speech perception appear to share a profile of arrays that are tilted superiorly as compared to recipients with lower speech perception levels. These ABI recipients have a high number of active electrodes (10 or more) and require less electrical charge on individual electrodes to achieve optimal stimulation.

3D-printed tracheoesophageal puncture and prosthesis placement simulator.

OBJECTIVES: A tracheoesophageal prosthesis (TEP) allows for speech after total laryngectomy. However, TEP placement is technically challenging, requiring a coordinated series of steps. Surgical simulators improve technical skills and reduce operative time. We hypothesize that a reusable 3-dimensional (3D)-printed TEP simulator will facilitate comprehension and rehearsal prior to actual procedures. METHODS: The simulator was designed using Fusion360 (Autodesk, San Rafael, CA). Components were 3D-printed in-house using an Ultimaker 2+ (Ultimaker, Netherlands). Squid simulated the common tracheoesophageal wall. A Blom-Singer TEP (InHealth Technologies, Carpinteria, CA) replicated placement. Subjects watched an instructional video and completed pre- and post-simulation surveys. RESULTS: The simulator comprised 3D-printed parts: the esophageal lumen and superficial stoma. Squid was placed between components. Ten trainees participated. Significant differences existed between junior and senior residents with surveys regarding anatomy knowledge(p<0.05), technical details(p<0.01), and equipment setup(p<0.01). Subjects agreed that simulation felt accurate, and rehearsal raised confidence in future procedures. CONCLUSIONS: A 3D-printed TEP simulator is feasible for surgical training. Simulation involving multiple steps may accelerate technical skills and improve education.

Auditory Brainstem Implant Array Position Varies Widely Among Adult and Pediatric Patients and Is Associated With Perception.

OBJECTIVES: The auditory brainstem implant (ABI) provides sound awareness to patients who are ineligible for cochlear implantation. Auditory performance varies widely among similar ABI cohorts. We hypothesize that differences in electrode array position contribute to this variance. Herein, we classify ABI array position based on postoperative imaging and investigate the relationship between position and perception. DESIGN: Retrospective review of pediatric and adult ABI users with postoperative computed tomography. To standardize views across subjects, true axial reformatted series of scans were created using the McRae line. Using multiplanar reconstructions, basion and electrode array tip coordinates and array angles from vertical were measured. From a lateral view, array angles (V) were classified into types I to IV, and from posterior view, array angles (T) were classified into types A to D. Array position was further categorized by measuring distance vertical from basion (D1) and lateral from midline (D2). Differences between array classifications were compared with audiometric thresholds, number of active electrodes, and pitch ranking. RESULTS: Pediatric (n = 4, 2 with revisions) and adult (n = 7) ABI subjects were included in this study. Subjects had a wide variety of ABI array angles, but most were aimed superiorly and posteriorly (type II, n = 7) from lateral view and upright or medially tilted from posterior view (type A, n = 6). Mean pediatric distances were 8 to 42% smaller than adults for D1 and D2. In subjects with perceptual data, electrical thresholds and the number of active electrodes differed among classification types. CONCLUSIONS: In this first study to classify ABI electrode array orientation, array position varied widely. This variability may explain differences in auditory performance.

Defining the Learning Curve for Endoscopic Ear Skills Using a Modular Trainer: A Multi-Institutional Study.

OBJECTIVE: Quantify the learning curve for endoscopic ear skills acquisition in otolaryngology residents using a simulator. The secondary objective was to determine if demographic factors or previous endoscopic experience influenced skill development. STUDY DESIGN: Prospective, multicenter study. Resident participants each completed 10 amassed trials using a validated endoscopic ear skill trainer. SETTING: Two academic teaching hospitals. SUBJECTS: Otolaryngology residents. MAIN OUTCOME MEASURES: Trial completion times; rate of improvement over time. RESULTS: Thirty-eight residents completed the study, 26 from program A and 12 from program B. Fifteen participants were women and 23 were men. Mean age was 30 years old (range 26 to 34 years). Previous experience with otoendoscopy (B = -16.7, p = 0.005) and sinus endoscopy (B = -23.4, p = 0.001) independently correlated with lower overall trial times. Age, gender, postgraduate year, handedness, interest in otology, and video gaming were not associated with trial times. On multivariate logistic regression, resident completion times improved with trial number, and residents without previous endoscopy experience improved at a faster rate than those with experience ( p < 0.001). CONCLUSIONS: Novice surgeons may acquire basic endoscopic ear experience with self-directed simulation training. The learning curve for transcanal endoscopic ear surgery is comparable to those demonstrated for other otologic surgeries, and specific task competencies can be achieved within 10 trials, suggesting that previous experiences, or lack thereof, may not dictate the ability to acquire new skills. There may be a translational value to previous endoscopic sinus experience on learning transcanal endoscopic ear surgery.

Utility of Augmented Reality and Virtual Reality in Spine Surgery: A Systematic Review of the Literature.

BACKGROUND: Augmented reality (AR), virtual reality (VR), and mixed reality (MR) are emerging technologies that are starting to be translated into clinical practice. Limited data are available regarding these tools in use during live surgery of the spine. Our objective was to systematically collect, analyze, and interpret the existing data regarding AR, VR, and MR use in spine surgery on living people. METHODS: A systematic review was conducted using the PRISMA (preferred reporting items for systematic reviews and meta-analyses) guidelines. The PubMed, PubMed Central, Cochrane Reviews, and Embase databases were searched. Combinations and variations of the phrases "augmented reality," "virtual reality," and spine surgery using both "AND" and "OR" configurations were used to find relevant studies. The references of the included reports from the systematic review were also screened for possible inclusion as a part of a manual review. The included studies were full-text publications written in English that had included any spine surgery on live persons with the use of VR or AR. RESULTS: A total of 1566 unique reports were found, and 15 full-text publications met the criteria for the present study. The total number of patients from all studies was 241, with a weighted average age of 50.37 years. Surgical procedures using AR, VR, and/or MR were diverse and spanned from simple discectomy to intradural spinal tumor resection. All patients experienced improvement in their symptoms present at clinical presentation. The highest complication rate reported in the studies was 6.1% and was for suboptimal pedicle screw placement. No complications led to clinical sequelae. CONCLUSIONS: The systematically collected, analyzed, and interpreted data of existing peer-reviewed full-text articles showed favorable metrics regarding surgical efficacy, pedicle screw target accuracy, radiation exposure, clinical outcomes, and disability and pain for patients with spinal pathology treated with the help of AR, VR, and/or MR.

Three-Dimensional Printing in Neurosurgery Residency Training: A Systematic Review of the Literature.

BACKGROUND: The use of three-dimensional (3D) printing in neurosurgery has become more prominent in recent years for surgical training, preoperative planning, and patient education. Several smaller studies are available using 3D printing; however, there is a lack of a concise review. This article provides a systematic review of 3D models in use by neurosurgical residents, with emphasis on training, learning, and simulation. METHODS: A structured literature search of PubMed and Embase was conducted using PRISMA guidelines to identify publications specific to 3D models trialed on neurosurgical residents. Criteria for eligibility included articles discussing only neurosurgery, 3D models in neurosurgery, and models specifically tested or trialed on residents. RESULTS: Overall, 40 articles were identified that met inclusion criteria. These studies encompassed different neurosurgical areas including aneurysm, spine, craniosynostosis, transsphenoidal, craniotomy, skull base, and tumor. Most articles were related to brain surgery. Of these studies, vascular surgery had the highest overall, with 13 of 40 articles, which include aneurysm clipping and other neurovascular surgeries. Twenty-two articles discussed cranial plus tumor surgeries, which included skull base, craniotomy, craniosynostosis, and transsphenoidal. Five studies were specific to spine surgery. Subjective outcome measures of neurosurgical residents were most commonly implemented, of which results were almost unanimously positive. CONCLUSIONS: 3D printing technology is rapidly expanding in health care and neurosurgery in particular. The technology is quickly improving, and several studies have shown the effectiveness of 3D printing for neurosurgical residency education and training.

New Navigation Approaches for Endoscopic Lateral Skull Base Surgery.

Image-guided navigation is well established for surgery of the brain and anterior skull base. Although navigation workstations have been used widely by neurosurgeons and rhinologists for decades, utilization in the lateral skull base (LSB) has been less due to stricter requirements for overall accuracy less than 1 mm in this region. Endoscopic approaches to the LSB facilitate minimally invasive surgeries with less morbidity, yet there are risks of injury to critical structures. With improvements in technology over the years, image-guided navigation for endoscopic LSB surgery can reduce operative time, optimize exposure for surgical corridors, and increase safety in difficult cases.

Teaching Endoscopic Ear Surgery.

Endoscopic ear surgery (EES) has become an integral part of otologic surgery. Training in EES involves learning fundamental techniques for endoscopic visualization, becoming proficient at one-handed dissection, mastering use of instruments designed for endoscopic ear surgery, and learning to optimize the operating room setup specifically for EES. Despite the steep learning curve, EES offers several advantages over the microscope for otologic procedures. With the rise in the demand for minimally invasive approaches, EES has a clear role in the future of otologic surgery. Identifying strategies to improve the training process of EES for the novice and experienced otolaryngologist is paramount.

Integrating Stereoscopic Video with Modular 3D Anatomic Models for Lateral Skull Base Training.

Introduction Current virtual reality (VR) technology allows the creation of instructional video formats that incorporate three-dimensional (3D) stereoscopic footage.Combined with 3D anatomic models, any surgical procedure or pathology could be represented virtually to supplement learning or surgical preoperative planning. We propose a standalone VR app that allows trainees to interact with modular 3D anatomic models corresponding to stereoscopic surgical videos. Methods Stereoscopic video was recorded using an OPMI Pentero 900 microscope (Zeiss, Oberkochen, Germany). Digital Imaging and Communications in Medicine (DICOM) images segmented axial temporal bone computed tomography and each anatomic structure was exported separately. 3D models included semicircular canals, facial nerve, sigmoid sinus and jugular bulb, carotid artery, tegmen, canals within the temporal bone, cochlear and vestibular aqueducts, endolymphatic sac, and all branches for cranial nerves VII and VIII. Finished files were imported into the Unreal Engine. The resultant application was viewed using an Oculus Go. Results A VR environment facilitated viewing of stereoscopic video and interactive model manipulation using the VR controller. Interactive models allowed users to toggle transparency, enable highlighted segmentation, and activate labels for each anatomic structure. Based on 20 variable components, a value of 1.1 × 10 12 combinations of structures per DICOM series was possible for representing patient-specific anatomy in 3D. Conclusion This investigation provides proof of concept that a hybrid of stereoscopic video and VR simulation is possible, and that this tool may significantly aid lateral skull base trainees as they learn to navigate a complex 3D surgical environment. Future studies will validate methodology.

Transcanal Computed Tomography Views for Transcanal Endoscopic Lateral Skull Base Surgery: Pilot Cadaveric Study.

Objective Transcanal endoscopic operative approaches provide for a minimally invasive surgical portal to the lateral skull base. Traditional preoperative imaging evaluation involves computed tomography (CT) acquisition in the axial and coronal planes that are not optimized for the transcanal surgical corridor. Herein, we describe a novel CT-based "transcanal view" for preoperative surgical planning and intraoperative navigation. Study Design Present study is a cadaveric imaging study. Methods Cadaveric temporal bones ( n = 6) from three specimens underwent high-resolution CT (0.625 mm slice thickness). Using three-dimensional (3D) Slicer 4.8, reformatted "transcanal" views in the plane of the external auditory canal (EAC) were created. Axial and coronal reformats were used to compare and measure distances between anatomic structures in the plane of the EAC. Results The degree of oblique tilt for transcanal CT reformats was 6.67 ± 1.78 degrees to align the EAC in axial and coronal planes. Anticipated critical landmarks were identified easily using the transcanal view. Mean values were 8.68 ± 0.38 mm for annulus diameter, 9.5 ± 0.93 mm for isthmus diameter, 10.27 ± 0.73 mm for distance between annulus and isthmus, 2.95 ± 0.13 mm for distance between annulus and stapes capitulum, 5.12 ± 0.35 mm for distance between annulus and mastoid facial nerve, and 19.54 ± 1.22 mm for EAC length. Conclusion This study is the first to illustrate a novel "transcanal" CT sequence intended for endoscopic lateral skull base surgery. Future studies may address how incorporation of a transcanal CT reformat may influence surgical decision making.

Diagnosis of Stapedial Myoclonus Using Endoscopic Visualization.

BACKGROUND: Stapedial myoclonus is an uncommon condition involving the rhythmic contraction of the stapedial tendon that may result in a host of symptoms, including tinnitus . There is a dearth of robust diagnostic modalities to diagnose stapedial myoclonus, and most patients are treated without definitive diagnosis. Herein, we hypothesize that stapedial myoclonus can be readily diagnosed by awake otoendoscopy (see Video, Supplemental Digital Content 1, http://links.lww.com/MAO/A997). CASE REPORT: A 21-year-old healthy male professional singer presented with a rhythmic "thumping sound" heard in both ears for 5 years. Symptoms were triggered by singing and were worse on the right side. Work-up, including otologic exam, audiologic testing, and high resolution imaging, was unrevealing. Given symptomatology, stapedial tendon myoclonus was suspected.While awake in the operating room, an inferior myringotomy was made, and both 1.9 mm 0 and 30 degree 3-CCD Hopkins rod endoscopes were used to visualize the middle ear space using a transcanal approach. There was robust movement of the tendon with patient vocalization that corresponded precisely with the timing of tinnitus. The patient subsequently underwent transection of the right stapedial tendon under general anesthesia using otoendoscopic visualization. The pyramidal eminence was also removed to avoid future regeneration. The patient underwent an identical procedure on the contralateral ear 3 months later with complete resolution of symptoms bilaterally. CONCLUSION: Stapedial myoclonus was diagnosed by transtympanic otoendoscopy in an awake patient. This approach may be readily applied in awake patients suspected of having stapedial myoclonus. Transection of the stapedial tendon in these patients resolves tinnitus.

Underwater Endoscopic Repair of Superior Canal Dehiscence.

: Superior canal dehiscence (SCD) is a bony defect of the superior semicircular canal (SCC). Patients with SCD Syndrome (SCDS) may experience symptoms such as aural fullness, pulsatile tinnitus, hyperacusis, autophony, or pressure or noise-induced vertigo . The defect can be repaired in various ways, but there is potential for loss of perilymphatic fluid during transmastoid approaches that could result in postoperative sensorineural hearing loss . We hypothesize that if the procedure were performed "underwater" in balanced salt solution (BSS), loss of perilymphatic fluid would be minimized. CASE REPORT:: A 55-year-old male presented with right-sided autophony, pulsatile tinnitus, and hyperacusis. Audiometric testing demonstrated a low-frequency airbone gap and a supranormal bone-conduction threshold at 4 kHz. Ocular VEMP responses were increased amplitude. Temporal bone imaging revealed a SCC dehiscence.The patient was taken to the operating room for an underwater, endoscopic repair of the SCC using a transmastoid approach. A cortical mastoidectomy was performed using Landmarx image navigation. BSS filled the mastoid and a 0-degree endoscope with endoscrub was used to see the SCC underwater. The SCC was entered near the ampullated end with a bur. A stepwise plugging process included applying strips of wet and dried fascia and bone dust. The non-ampullated end was similarly plugged. BSS was suctioned, and under microscopic visualization, labyrinthotomies were capped with bone chips. The patient tolerated the procedure well and was discharged the next day. There was no sensorineural hearing loss postoperatively. CONCLUSION:: SCDS may be addressed surgically using multiple approaches. An underwater endoscopic repair of the SCC may be safe and effective surgical treatment.SDC video link: http://links.lww.com/MAO/A808.

Combining Stereoscopic Video and Virtual Reality Simulation to Maximize Education in Lateral Skull Base Surgery.

Mastery of lateral skull base (LSB) surgery requires thorough knowledge of complex, 3-dimensional (3D) microanatomy and techniques. While supervised operation under binocular microscopy remains the training gold standard, concerns over operative time and patient safety often limit novice surgeons' stereoscopic exposure. Furthermore, most alternative educational resources cannot meet this need. Here we present proof of concept for a tool that combines 3D-operative video with an interactive, stereotactic teaching environment. Stereoscopic video was recorded with a microscope during translabyrinthine approaches for vestibular schwannoma. Digital imaging and communications in medicine (DICOM) temporal bone computed tomography images were segmented using 3D-Slicer. Files were rendered using a game engine software built for desktop virtual reality. The resulting simulation was an interactive immersion combining a 3D operative perspective from the lead surgeon's chair with virtual reality temporal bone models capable of hands-on manipulation, label toggling, and transparency modification. This novel tool may alter LSB training paradigms.

Virtual coach: the next tool in functional endoscopic sinus surgery education.

BACKGOUND: Functional endoscopic sinus surgery (FESS) can be challenging as novices become accustomed to handling endoscopes and instruments while navigating complex sinonasal anatomy. Experts demonstrate fluid and efficient motions when addressing pathology. The training process from novice to expert relies on hands-on experience in cadaveric laboratories and preceptorship models that require significant time and expense. This study aims to validate the use of a virtual coach to guide users step-by-step through a basic FESS. METHODS: Seventeen surgeons were grouped into novice (n = 10) and expert (n = 7) based on self-reported levels of surgical experience. Users were trained using the maxillary antrostomy module in the Neurorhinological Surgery (NRS) simulator combining the physical craniofacial model with virtual reality (VR)-tracked surgical instruments in the VR operating room. The virtual coach guided the user using surgical videos, auditory, and visual cues. The coach recorded data for each subject including the number of times borders of the nasal cavity were encountered and time to completion. Users graded the usefulness of the virtual coach on a Likert questionnaire. RESULTS: Face validity of our NRS simulator was replicated by user questionnaires, and construct validity replicated by differentiation between novice and expert level surgeons (p < 0.01). Novices contacted a significantly higher number of anatomic borders (n = 17) and had a longer operative time (t = 370 seconds). All users reported high scores on the benefit and usefulness of the virtual coach. CONCLUSION: The virtual coach provides a useful tool to enhance FESS education by providing objective real-time data in a novel mixed-reality surgical environment.

Effect of anesthesia on evoked auditory responses in pediatric auditory brainstem implant surgery.

OBJECTIVE: Electrically evoked auditory brainstem responses (EABR) guide placement of the multichannel auditory brainstem implant (ABI) array during surgery. EABRs are also recorded under anesthesia in nontumor pediatric ABI recipients prior to device activation to confirm placement and guide device programming. We examine the influence of anesthesia on evoked response morphology in pediatric ABI users by comparing intraoperative with postoperative EABR recordings. STUDY DESIGN: Retrospective review. METHODS: Seven children underwent ABI surgery by way of retrosigmoid craniotomy. General anesthesia included inhaled sevoflurane induction and propofol maintenance during which EABRs were recorded to confirm accurate positioning of the ABI. A mean of 7.7 ± 2.8 weeks following surgery, the ABI was activated under general anesthesia or sedation (dexmedetomidine) and EABR recordings were made. A qualitative analysis of intraoperative and postoperative waveform morphology was performed. RESULTS: Seven subjects (mean age 20.6 months) underwent nine ABI surgeries (seven primary, two revisions) and nine activations. EABRs were observed in eight of nine postoperative recordings. In three cases, intraoperative EABRs during general anesthesia were similar to postoperative EABRs with sedation. In one case, sevoflurane and propofol were used for intra- and postoperative recordings, and waveforms were also similar. In four cases, amplitude and latency changes were observed for intraoperative versus postoperative EABRs. CONCLUSION: Similarity of EABR morphology in the anesthetized versus sedated condition suggests that anesthesia does not have a large effect on far-field evoked potentials. Changes in EABR waveform morphology observed postoperatively may be influenced by other factors such as movements of the surface array. LEVEL OF EVIDENCE: 4 Laryngoscope, 130:507-513, 2020.

Image-Guided Mastoidectomy with a Cooperatively Controlled ENT Microsurgery Robot.

Mastoidectomy is a common surgical procedure within otology. Despite being inherently well suited for implementation of robotic assistance, there are no commercially available robotic systems that have demonstrated utility in aiding with this procedure. This article describes a robotic technique for image-guided mastoidectomy with an experimental cooperatively controlled robotic system developed for use within otolaryngology-head and neck surgery. It has the ability to facilitate enhanced operative precision with dampening of tremor in simulated surgical tasks. Its kinematic design is such that the location of the attached surgical instrument is known with a high degree of fidelity at all times. This facilitates image registration and subsequent definition of virtual fixtures, which demarcate surgical workspace boundaries and prevent motion into undesired areas. In this preliminary feasibility study, we demonstrate the clinical utility of this system to facilitate performance of a cortical mastoidectomy by a novice surgeon in 5 identical temporal bone models with a mean time of 221 ± 35 seconds.

Initial Experience with 3-Dimensional Exoscope-Assisted Transmastoid and Lateral Skull Base Surgery.

Extracorporeal video microscopes, or "exoscopes," provide high-definition views of the operative field and are alternatives to the operating microscope or loupes for large-corridor surgical approaches. In this proof-of-concept study, we aim to determine the feasibility of 3-dimensional exoscopes as alternatives to operating microscopes in otology and neurotology, espeically in conjunction with endoscopes. Eleven consecutive cases were performed using 3-dimensional exoscopes in place of, or as adjuncts to, the operating microscope. The exoscope was the sole visualization tool in 7 cases, with 4 including the use of an endoscope or microscope. There were no perioperative complications. Potential subjective advantages include superior ergonomics, compact size, and an equal visual experience for surgeons and observers. Limitations include low lighting in small surgical corridors and pixilation at high magnification. Exoscopes are potentially viable alternatives to the microscope in otologic and neurotologic surgery.

High Resolution Computed Tomography Atlas of the Porcine Temporal Bone and Skull Base: Anatomical Correlates for Traumatic Brain Injury Research.

Brain injuries are a significant cause of morbidity and mortality worldwide. Auditory and vestibular dysfunction may occur following trauma to the temporal bone (TB), including the lateral skull base. The porcine model is a commonly used large animal model for investigating brain injury. Reports detailing porcine TB anatomy based on high resolution computed tomography (HRCT) imaging, however, are limited. Herein, we employ HRCT to evaluate and describe the bony anatomy of the porcine TB and lateral skull base. High-resolution multi-detector and cone beam CT were used to image porcine TBs (n = 16). TBs were analyzed for major anatomical structures and compared to human species. Porcine temporal bone anatomy was readily identifiable by HRCT. Although some variability exists, the ossicular chain, vestibule, cochlea, course of the facial nerve, and skull base are similar to those of humans. Major differences included position of the external auditory canal and mastoid, as well as presence of the petrous carotid canal. Study findings may serve as an atlas to evaluate the porcine middle and inner ear, as well as lateral skull base injuries for future porcine brain injury models or other studies that require CT-based analysis.

Virtual Functional Endoscopic Sinus Surgery Simulation with 3D-Printed Models for Mixed-Reality Nasal Endoscopy.

The surgeon's knowledge of a patient's individual anatomy is critical in skull base surgery. Trainees and experienced surgeons can benefit from surgical simulation; however, current models are expensive and impractical for widespread use. In this study, we report a next-generation mixed-reality surgical simulator. We segmented critical anatomic structures for 3-dimensional (3D) models to develop a modular teaching tool. We then developed a navigation tracking system utilizing a 3D-printed endoscope as a trackable virtual-reality (VR) controller and validated the accuracy on VR and 3D-printed skull models within 1 cm. We combined VR and augmented-reality visual cues with our 3D physical model to simulate sinus endoscopy and highlight segmented structures in real time. This report provides evidence that a mixed-reality simulator combining VR and 3D-printed models is feasible and may prove useful as an educational tool that is low cost and customizable.