Jordan B. Hochman

Generation of a 3D printed temporal bone model with internal fidelity and validation of the mechanical construct.

Objective To generate a rapid-prototyped temporal bone model from computed tomography (CT) data with a specific focus on internal anatomic fidelity. Study Design Research ethics board-approved prospective cohort study. Setting Current iterations of a rapid-prototyped temporal bone model are complicated by absent void spaces and inconsistent bone density due to limited infiltrant exposure. The creation of a high-fidelity model allows surgical trainees to practice in a standardized and reproducible training environment. This learning paradigm will significantly augment resident understanding of surgical approaches and techniques to prevent adverse outcomes. Subjects and Methods We describe a technique for generating internally accurate rapid-prototyped anatomical models with solid and hollow structures, including void spaces. The novel slicing algorithm digitally deconstructs a model into segments and permits removal of extraneous print material and allows infiltrant penetration of the entire bone structure. Precise reassembly is facilitated by digitally generated fiducials. Infiltrant of choice was determined by expert assessment and subjected to objective mechanical property assessment with comparison to cadaveric sheep bone. Results The printed bone models are highly realistic. Void space representation was excellent with 88% concordance between cadaveric bone and the resultant rapid-prototyped temporal bone model. Ultimately, cyanoacrylate with hydroquinone was determined to be the most appropriate infiltrant for both cortical and trabecular simulation. The mechanical properties of all tested infiltrants were similar to real bone. Conclusion This model serves as an excellent replica of a human temporal bone for training and preoperative surgical rehearsal and can be dissected in a true-to-life fashion.

Post—Tympanostomy Tube Otorrhea: A Meta-Analysis

INTRODUCTION: Post—tympanostomy tube otorrhea is the most common complication of tympanostomy tube placement. The incidence of this problem varies from 3.4% to 74%. Trials that study post—tympanostomy tube otorrhea may involve valid randomization “by patient” or “by ear.” In an attempt to define “best practice,” we conduct a meta-analysis to quantify the benefit of using topical prophylactic antibiotic drops in the postoperative period. We then compare our findings with previous results found in the literature. METHODS: We selected randomized studies for which antibiotic drops had been used for at least 48 hours after tympanostomy tube insertion. Nine studies, 3 “by ear” and 6 “by patient,” met our inclusion criteria. The odds ratio and 95% confidence intervals were calculated for each to conduct the meta-analysis. RESULTS: Overall, prophylaxis appears to be effective at reducing the incidence of post—tympanostomy tube otorrhea. The odds ratios for all studies were less than 1.0. However, none of the 3 “by ear” studies and only 3 of the 6 “by patient” studies were statistically significant. The mean odds ratio was 52%, suggesting that prophylaxis may reduce the incidence of post—tympanostomy tube otorrhea by half. CONCLUSION: This meta-analysis suggests that routine post—tympanostomy tube prophylaxis is beneficial, but this finding is dependent on selection criteria used. EBM rating: A-1a

Comparison of cadaveric and isomorphic three-dimensional printed models in temporal bone education.

Current three‐dimensional (3D) printed simulations are complicated by insufficient void spaces and inconsistent density. We describe a novel simulation with focus on internal anatomic fidelity and evaluate against template/identical cadaveric education.

Prevalence of Connexin 26 (GJB2) and Pendred (SLC26A4) mutations in a population of adult cochlear implant candidates.

Objective: To assess the prevalence of Connexin 26 (GJB2), Connexin 30 (GJB6), and Pendred (SLC26A4) mutations in a population of adult cochlear implant patients with a history of either early idiopathic or hereditary progressive sensorineural deafness. Background: Significant efforts have been applied in defining the epidemiology of Connexin 26 (GJB2)-associated hearing impairment in the pediatric population, yet the issue remains ambiguous for adult patients. Causation is important in this population because there are implications to prognosis, risk of associated medical manifestations, and for genetic counseling purposes. Patients: Adult patients meeting criteria for cochlear implantation with early-onset hearing loss assessed at an adult cochlear implant center from November 2007 to April 2009. Intervention: Genomic DNA samples from whole blood were tested with bidirectional sequence analysis for mutations in the coding region of the GJB2 and SLC26A4 genes and tested for large deletions of the GJB6 gene. Results: Fifty-seven patients were analyzed for GJB2 mutations. Eight patients (14%) were found to have GJB2-related hearing impairment; 5 patients were homozygous for the c.35delG mutation (genotype c.35delG/c.35delG), and 3 additional patients were compound heterozygotes with 2 different GJB2 mutations. Of these 8 patients with GJB2-related hearing impairment, 3 had serviceable hearing into their teenage years. One additional patient had 1 GJB2 variant (p.Met195Ile, heterozygous). None had GJB6 mutations. Of the 57 patients, 30 were also analyzed for SLC26A4 mutations. Three of these patients were compound heterozygotes for disease-causing SLC26A4 mutations, confirming SLC26A4-related hearing impairment. Three additional patients were found to have a single variant in SLC26A4. Conclusion: The prevalence of GJB2- and SLC26A4-related hearing impairment in an adult population with early-onset severe sensorineural hearing loss is significant, suggesting the need for routine assessment for genetic etiologies in this group. We also note 3 individuals with causal connexin 26 mutations with subjective serviceable hearing into adolescence in our cohort.

End User Comparison of Anatomically Matched 3-Dimensional Printed and Virtual Haptic Temporal Bone Simulation: A Pilot Study.

Objective Simulation has assumed a prominent role in education. It is important to explore the effectiveness of different modalities. In this article, we directly compare surgical resident impression of 2 distinct temporal bone simulations (physical and haptic). Study Design Research Ethics Board–approved prospective cohort study. Setting A haptic voxel-based virtual model (VM) and a physical 3-dimensional printed temporal bone model (PBM) were developed. Participants rated each construct on a number of parameters and performed a direct comparison of the simulations using a survey instrument that employed a 7-point Likert scale and rank lists. Subjects and Methods Ten otolaryngology residents dissected anatomically identical, matched physical and virtual models. Data for both simulations originated from 10 unique cadaveric micro–computed tomography images. Results Subjects rated the PBM drill quality as being more similar to cadaveric temporal bone than the VM (cortical bone mean: 5.5 vs 3.2, P = .011; trabecular bone mean: 5.2 vs 2.8, P = .004) and with better air cell system representation (mean: 5.4 vs 4.5, P = .003). Subjects strongly agreed that both simulations are effective educational tools, but they rated the PBM higher (mean: 6.7 vs 5.4, P = .019). Notably, subjects agreed that both modalities should be integrated into training, but they were more favorably inclined toward the PBM (mean: 7.0 vs 5.5, P = .002). In direct comparison, the PBM was the preferred simulation in 7 of 9 educational domains. Conclusions Appraisal of a PBM and a VM found both to have perceived educational benefit. However, the PBM was considered to have more realistic physical properties and was considered the preferred training instrument.

Comparison of cadaveric and isomorphic virtual haptic simulation in temporal bone training

BackgroundVirtual surgery may improve learning and provides an opportunity for pre-operative surgical rehearsal. We describe a novel haptic temporal bone simulator specifically developed for multicore processing and improved visual realism. A position locking algorithm for enhanced drill-bone interaction and haptic fidelity is further employed. The simulation construct is evaluated against cadaveric education.MethodsA voxel-based simulator was designed for multicore architecture employing Marching Cubes and Laplacian smoothing to perform real-time haptic and graphic rendering of virtual bone.Ten Otolaryngology trainees dissected a cadaveric temporal bone (CTB) followed by a virtual isomorphic haptic model (VM) based on derivative microCT data. Participants rated 1) physical characteristics, 2) specific anatomic constructs, 3) usefulness in skill development and 4) perceived educational value. The survey instrument employed a Likert scale (1-7).ResultsResidents were equivocal about the physical properties of the VM, as cortical (3.2 ± 2.0) and trabecular (2.8 ± 1.6) bone drilling character was appraised as dissimilar to CTB. Overall similarity to cadaveric training was moderate (3.5 ± 1.8). Residents generally felt the VM was beneficial in skill development, rating it highest for translabyrinthine skull-base approaches (5.2 ± 1.3). The VM was considered an effective (5.4 ± 1.5) and accurate (5.7 ± 1.4) training tool which should be integrated into resident education (5.5 ± 1.4). The VM was thought to improve performance (5.3 ± 1.8) and confidence (5.3 ± 1.9) and was highly rated for anatomic learning (6.1 ± 1.9).ConclusionStudy participants found the VM to be a beneficial and effective platform for learning temporal bone anatomy and surgical techniques. They identify some concern with limited physical realism likely owing to the haptic device interface. This study is the first to compare isomorphic simulation in education. This significantly removes possible confounding features as the haptic simulation was based on derivative imaging.

Temporal bone surgical simulation employing a multicore architecture

This paper presents a novel haptic temporal bone surgery simulator. Temporal bone surgery is challenging as anatomic structures are complex and encased within bone. The new simulator is designed to train surgical residents permitting virtual practice of complex patient specific procedures before actual surgery is performed. The simulation employs voxels for collision detection and bone removal. It is designed to run on multicore computers that allow it to render changes in the temporal bone using Marching Cubes and Laplacian HC smoothing, in real time. This approach allows the use of consumer level hardware to display the simulation in stereo 3D, and serves as a vehicle for several new training tools, now incorporated into the simulation. Future plans include trials of validity, efficacy and cost effective integration into training and surgical rehearsal.

Mixed reality temporal bone surgical dissector: mechanical design

ObjectiveThe Development of a Novel Mixed Reality (MR) Simulation.An evolving training environment emphasizes the importance of simulation. Current haptic temporal bone simulators have difficulty representing realistic contact forces and while 3D printed models convincingly represent vibrational properties of bone, they cannot reproduce soft tissue. This paper introduces a mixed reality model, where the effective elements of both simulations are combined; haptic rendering of soft tissue directly interacts with a printed bone model.This paper addresses one aspect in a series of challenges, specifically the mechanical merger of a haptic device with an otic drill. This further necessitates gravity cancelation of the work assembly gripper mechanism. In this system, the haptic end-effector is replaced by a high-speed drill and the virtual contact forces need to be repositioned to the drill tip from the mid wand.Previous publications detail generation of both the requisite printed and haptic simulations.MethodCustom software was developed to reposition the haptic interaction point to the drill tip. A custom fitting, to hold the otic drill, was developed and its weight was offset using the haptic device. The robustness of the system to disturbances and its stable performance during drilling were tested. The experiments were performed on a mixed reality model consisting of two drillable rapid-prototyped layers separated by a free-space. Within the free-space, a linear virtual force model is applied to simulate drill contact with soft tissue.ResultsTesting illustrated the effectiveness of gravity cancellation. Additionally, the system exhibited excellent performance given random inputs and during the drill’s passage between real and virtual components of the model. No issues with registration at model boundaries were encountered.ConclusionThese tests provide a proof of concept for the initial stages in the development of a novel mixed-reality temporal bone simulator.

Gesture-controlled interactive three dimensional anatomy: a novel teaching tool in head and neck surgery.

BackgroundThere is a need for innovative anatomic teaching tools. This paper describes a three dimensional (3D) tool employing the Microsoft Kinect ™. Using this instrument, 3D temporal bone anatomy can be manipulated with the use of hand gestures, in the absence of mouse or keyboard.MethodsCT Temporal bone data is imported into an image processing program and segmented. This information is then exported in polygonal mesh format to an in-house designed 3D graphics engine with an integrated Microsoft Kinect™. Motion in the virtual environment is controlled by tracking hand position relative to the user’s left shoulder.ResultsThe tool successfully tracked scene depth and user joint locations. This permitted gesture-based control over the entire 3D environment. Stereoscopy was deemed appropriate with significant object projection, while still maintaining the operator’s ability to resolve image details. Specific anatomical structures can be selected from within the larger virtual environment. These structures can be extracted and rotated at the discretion of the user. Voice command employing the Kinect’s™ intrinsic speech library was also implemented, but is easily confounded by environmental noise.ConclusionThere is a need for the development of virtual anatomy models to complement traditional education. Initial development is time intensive. Nonetheless, our novel gesture-controlled interactive 3D model of the temporal bone represents a promising interactive teaching tool utilizing a novel interface.

Simplified Summative Temporal Bone Dissection Scale Demonstrates Equivalence to Existing Measures

Introduction: Emphasis on patient safety has created the need for quality assessment of fundamental surgical skills. Existing temporal bone rating scales are laborious, subject to evaluator fatigue, and contain inconsistencies when conferring points. To address these deficiencies, a novel binary assessment tool was designed and validated against a well-established rating scale. Methods: Residents completed a mastoidectomy with posterior tympanotomy on identical 3D-printed temporal bone models. Four neurotologists evaluated each specimen using a validated scale (Welling) and a newly developed “CanadaWest” scale, with scoring repeated after a 4-week interval. Results: Nineteen participants were clustered into junior, intermediate, and senior cohorts. An ANOVA found significant differences between performance of the junior-intermediate and junior-senior cohorts for both Welling and CanadaWest scales (P < .05). Neither scale found a significant difference between intermediate-senior resident performance (P > .05). Cohen’s kappa found strong intrarater reliability (0.711) with a high degree of interrater reliability of (0.858) for the CanadaWest scale, similar to scores on the Welling scale of (0.713) and (0.917), respectively. Conclusion: The CanadaWest scale was facile and delineated performance by experience level with strong intrarater reliability. Comparable to the validated Welling Scale, it distinguished junior from senior trainees but was challenged in differentiating intermediate and senior trainee performance.