Validation of a Temporal Bone Dissection Simulator .Validation of a Temporal Bone Dissection Simulator

Validation of a Temporal Bone Dissection Simulator .Validation of a Temporal Bone Dissection Simulator

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  • Validation of a Temporal Bone Dissection SimulatorValidation of a Temporal Bone Dissection SimulatorJeff C. Rastatter, MD1,2; Sumit Bapna, MD1,2; Mark Packer, MD1,2; Don Stredney3 ; Gregory J. Wiet, MD1,2,3

    From the 1Department of Otolaryngology, Columbus Childrens Hospital, Columbus, Ohio and the 2Department of Otolaryngology Head and Neck Surgery, The Ohio State University Medical Center, Columbus, OH, and

    the 3Ohio Supercomputer Center, Columbus, OH

    AbstractAbstractEDUCATIONAL OBJECTIVETo increase our understanding of the effect of temporal bone simulator training on individuals ability to learn cadaveric temporal bone dissection.

    OBJECTIVESTo study the effect of virtual temporal bone dissection training on individuals ability to dissect cadaverictemporal bones.

    STUDY DESIGNProspective, randomized, blinded study.

    METHODSTwelve study subjects with no previous relevant training were recruited. All twelve subjects received similar standardized pretest education. Subjects were then randomized to 2 test groups. The simulator group was given unlimited access to the virtual temporal bone dissection instrument for individual practice over the next 2 weeks. The traditional group was given access to 2 cadaveric temporal bones each for individual practice over the next 2 weeks in the temporal bone laboratory. All subjects then dissected 2 cadaveric temporal bones for a post training test. The post test dissections were graded by two senior neurotologists using the Welling Scale.

    RESULTSThe traditional group had a mean percent of total possible Welling Scale points of 23% (range 8.6 46, STD 8.6), and the simulator group had a value of 17% (range 0 40, STD 8.5). The traditional group had a mean practice time of 2.5 hours (range 2.0 3.25, STD 0.56), and the simulator group had a mean practice time of 3.3 hours (range 0.75 5.0, STD 1.9).

    CONCLUSIONSSubjects from both study groups performed relatively similar to each other on post test cadaveric temporal bone dissection measured by the Welling Scale. The traditional group did, however, perform slightly better. This reslult is consistent with the hypothesis that practice on the temporal bone dissection simulator is beneficial, but not equivalent to traditional practice with cadavertic specimens. Further studies and refinement of the research protocol are needed to continue to evaluate the role temporal bone dissection simulators will play in the future.

    The objective measure of performance dissecting the post test cadaveric temporal bones for both study groups is detailed in Figure 2. The traditional group did slightly better than the simulator group, and the difference was statistically significant.

    The recorded total practice time for both groups is detailed in Figure 3. On average the simulator group practiced for a longer period of time.

    ResultsResults

    BibliographyBibliography

    Recruitment: 12 Subjects with no previous relevant training were recruited for the study: 6 medical students with an interest in surgery. 6 PGY 1 or 2 residents with no experience yet in mastoid surgery.

    Standardized pretest education given to all 12 study subjects. Access to relevant pages from the Temporal Bone Surgical Dissection Manual.10 30 minute lecture on relevant anatomy. 2 hour proctored dissection of cadaveric temporal bone. Instruction on how to use the Temporal Bone Dissection Simulator. 15 minute skills test on Temporal Bone Dissection Simulator Drill a cone off a sphere.

    Randomization: Subjects randomized between 2 study groups (6 each). Subjects from both groups recorded their total practice time.

    Traditional Group: Unlimited practice time with 2 new cadaveric temporal bones in the temporal bone dissection laboratory over 2 week period. Simulator Group: Unlimited practice time using the temporal bone dissection simulator over 2 week period.

    Post test dissection: All subjects dissected 2 cadaveric temporal bones.

    Data Analysis: The post test dissections were analyzed and scored by two neurotologistsusing the Welling Scale (Figure 1). Statistical analysis was done to compare the scores between study groups.

    Methods and MaterialsMethods and Materials

    While the traditional group did perform slightly better than the simulator group, the margin was not large. This is consistent with our hypothesis that training on the simulator would be beneficial but not equivalent to traditional training in the temporal bone laboratory. The similar performance could also be understood if neither group benefited from either training method. This possibility will become evident with further studies and refinement of the study protocol. Specifically, a multi-institutional study is needed with potentially longer training periods. The fact that the simulator group tended to practice more is interesting and may be due to easier access and setup relative to a temporal bone specimen in a lab.

    As the fidelity of temporal bone dissection simulators continues to advance, the potential role they could play in resident education remains an exciting and cutting edge area. Further studies will certainly be essential in defining the simulators place in surgical education.

    ConclusionsConclusions

    IntroductionIntroductionTraining to become an otologic surgeon involves years of study and practice by various methods. Traditional methods include studying books, illustrations, and anatomic models, and assisting established surgeons during operations. An important part of the learning process is dissection of cadaveric temporal bone specimens. Nearly all residency training programs have access to temporal bone dissection laboratories and incorporate these dissections into resident education and training.

    Working with cadaveric temporal bone specimens has inherent limitations and risks. Specimens are expensive, often are in short supply, and for the most part can only be dissected once. Further, working with human tissue has the potential to transmit disease. A potential solution to these issues is emerging through advancing technology and computer simulation.

    Harada first introduced the concept of utilizing 3-dimentional volumetric reconstructions from computed tomography to simulate temporal bone dissections.1 Technological limitations, however, prevented real time execution of this concept in the late 1980s. Advancing technology has allowed surface-based computer reconstruction models2 and volumetric physical based models.3,4,5

    For the past five years our group has been developing a temporal bone dissection simulator based on volumetric data sets from computed tomography.6,7,8 The system has haptic (or tactile) feedback for the user. Our group has also recently developed and validated the Welling Scale as an objective measure of temporal bone dissection quality.9 The goal of this current study is to evaluate the effectiveness of training with the temporal bone dissection simulator on subjects proficiency dissecting a cadaveric temporal bone.

    Please grade each item. 0 = incomplete, inadequate dissection, 1 = complete, adequateCortex1. Cortex rounded at linea temporalis 0 12. Cortex rounded from linea temporalis to middle cranial fossa 0 13. Thinning of posterior canal wall 0 14. Complete saucerization 0 1Tegmen mastoideum5. Dissection parallels curve of the dura 0 16. Completely exposed 0 17. No holes 0 18. No cells remain 0 1Sigmoid Sinus9. No holes 0 110. No cells 0 111. No overhang 0 1Sinodural Angle12. Sharp 0 113. No cells remaining 0 1Digastric Ridge14. Identified 0 115. Digastric tendon followed to stylomastoid foramen 0 1External Auditory Canal16. Canal Wall Up 0 117. Without holes 0 118. Without cells 0 1Semicircular Canals Skeletonized19. Horizontal 0 120. Superior 0 121. Posterior 0 122. Blue lined without fenestra 0 1Facial Nerve23. Identification of nerve at the stylomastoid foramen 0 124. Identification of nerve at the external genu 0 125. Identification tympanic segment 0 126. Identification of nerve at cochleariform process 0 127. No exposed nerve sheath 0 128. Identification of chorda tympani or stump 0 129. Facial Recess Completely exposed 0 1Additional Anatomical Structures30. Stapedial muscle dissected 0 131. ELS transition to duct 0 132. Blue line of basal turn of the cochlea 0 133. Identification of carotid artery in middle ear 0 134. Identification of jugular bulb 0 135. Skeletonization of jugular bulb 0 1

    TOTAL POINTSDifficulty of temporal bone

    1 2 3 4 5 Very Easy Easy Average Difficult Very Difficult

    Figure 1Figure 1Welling Scale for Evaluation of Temporal Bone DissectionsWelling Scale for Evaluation of Temporal Bone Dissections

    1. Harada T, Ishii S, and Tayama N, Three-dimensional Reconstruction of the Temporal Bone From Histological Sections, Arch Otolaryngol Head Neck Surg,1988;114:1139-1142.

    2. Serra L, Kockro R, Goh LC, Ng H, and ECK Lee, The DextroBeam: a stereoscopic presentation system for volumetric medical data, Proc. MMVR10, JD Westwood et al, (Eds.) IOS Press, Amsterdam, 2002, 478484.

    3. John N, et al, An Integrated Simulator for Surgery of the Petrous Bone Proc. MMVR9,2001:218-224.4. Agus M, Giachetti A, Gobbetti E, Zanetti G, Zorcolo A, John NW and RJ Stone, (2002) Mastoidectomy

    Simulation with Combined Visual and Haptic Feedback, Proc. MMVR10, J.D. Westwood et al, (Eds.) IOS Press, Amsterdam, 2002, 17-23.

    5. Agus M, Giachetti A, Gobbetti E, Zanetti G, Zorcolo and B Picasso, A Haptic Model of a Bone-Cutting Burr Proc. MMVR11, .J.D. Westwood et al, (Eds.) IOS Press, Amsterdam,4-10.

    6. Wiet GJ, Schmalbrock P, Powell K, Stredney D. Use of ultra-high-resolution data for temporal bone dissection simulation. Otolar