Comparison of Middle Ear Visualization With Endoscopy and Microscopy

TLDR

Chronic ear surgery aims to create a safe, dry ear, and complete cholesteatoma removal depends on visualization, which is limited by conventional microscopy but improved by endoscopy in certain middle‑ear subregions. The study quantitatively evaluates the visualization advantage of endoscopes over operating microscopes. Using a 3‑D temporal‑bone model, the authors simulated microscopic and endoscopic views, quantified subsegment visualization percentages for microscopes and 0°, 30°, and 45° endoscopes, and identified the optimal visualization mode for each anatomical region. 0‑degree endoscopes reveal more of each subregion than microscopes (except the antrum), and angled scopes visualize even more surface area, giving endoscopes an advantage for cholesteatoma dissection in hard‑to‑see areas such as the sinus tympani and epitympanum.

Abstract

Introduction: The primary goal of chronic ear surgery is the creation of a safe, clean dry ear. For cholesteatomas, complete removal of disease is dependent on visualization. Conventional microscopy is adequate for most dissection, but various subregions of the middle ear are better visualized with endoscopy. Objective: The purpose of the present study was to quantitatively assess the improved visualization that endoscopes afford as compared with operating microscopes. Methods: Microscopic and endoscopic views were simulated using a three-dimensional model developed from temporal bone scans. Surface renderings of the ear canal and middle ear subsegments were defined and the percentage of visualization of each middle ear subsegment, both with and without ossicles, was then determined for the microscope as well as for 0-, 30-, and 45-degree endoscopes. Using this information, we analyzed which mode of visualization is best suited for dissection within a particular anatomical region. Results: Using a 0-degree scope provides significantly more visualization of every subregion, except the antrum, compared with a microscope. In addition, angled scopes permit visualizing significantly more surface area of every subregion of the middle ear than straight scopes or microscopes. Conclusions: Endoscopes offer advantages for cholesteatoma dissection in difficult-to-visualize areas including the sinus tympani and epitympanum.