Article
Comparison of microscopic and endoscopic view of the internal auditory canal – A cadaveric study
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Authors
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Guilherme Ramina Montibeller
- Klinik für Neurochirurgie, Universitätsklinikum des Saarlandes und Medizinische Fakultät der Universität des Saarlandes, Homburg/Saar
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Fabian Fries
- Klinik für Neurochirurgie, Universitätsklinikum des Saarlandes und Medizinische Fakultät der Universität des Saarlandes, Homburg/Saar
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Ioannis Petrakakis
- Klinik für Neurochirurgie, Medizinische Hochschule Hannover, Hannover
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Kurt W. Becker
- Anatomie und Zellbiologie, Universitätsklinikum des Saarlandes und Medizinische Fakultät der Universität des Saarlandes, Homburg/Saar
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Joachim Oertel
- Klinik für Neurochirurgie, Universitätsklinikum des Saarlandes und Medizinische Fakultät der Universität des Saarlandes, Homburg/Saar
| Published: | May 13, 2014 |
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Outline
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Objective: Studies suggest that the endoscope could provide superior exposure of the internal auditory canal after microsurgical resection of intrameatal tumors. The aim of this study is to quantify the differences of the exposure of the internal auditory canal using the microscope and the endoscope.
Method: A retrosigmoid approach was performed on 6 cadaver heads. Computer tomography scans were used to plan the size of the craniotomy and perform anatomical measurements. A millimeter gauge was introduced inside the internal auditory canal, and examinations with surgical microscope and 0°, 30° and 70° rigid endoscopes were performed. The differences between the view of the microscope and different angled endoscopes were analyzed. Other anatomical measurements (length of the internal auditory canal, angle between anterior and posterior wall of the internal auditory canal, relation of sinus sigmoideus and the fundus, etc) were also performed and evaluated.
Results: The endoscope allowed an improved exposure of the internal auditory canal in all cases. With increasing angles of the endoscope, the internal auditory canal could be investigated more deeply. However, the distortion of the image gained increased also. The 0°, 30° and 70° endoscopes permitted an exposure that was respectively 2.1 (5 mm), 3 (7.125 mm) and 3.4 (8.125 mm) times more lateral than the microscopic view (2.375 mm) on average. A decreased necessity of retraction of structures to expose the internal auditory canal could also be noted when using the endoscope. The area inspected by the endoscope was not always accessible using regular microsurgical instruments. The working area was diminished as a result of the additional instrument brought into the operation area when using the endoscope.
Conclusions: The use of the endoscope for inspection of the internal auditory canal can be very useful during intrameatal tumor surgeries. The clear advantage gained by the use of different angled endoscopes in this region could be objectively demonstrated in this anatomical study. The combination of the qualities of both, microscope and endoscope, provided the best intrameatal visualization. Higher resolution, finer instruments and hands-on experience open the field for new surgical techniques to be thought of and developed.
