Abstract:ObjectiveTo evaluate the accuracy and reliability of preoperative thin slice computerized tomography (CT) and predict the difficulty of stapes exposure in ear microsurgery by measuring and comparing the preoperative CT imaging parameters.MethodsTwentyseven inpatients (27 ears) undergoing mastoid microsurgery due to chronic otitis media from Feb 2019 to Oct 2019 were enrolled in the study. The operation was performed via retroauricular approach by the same experienced associate senior doctor in all the patients. Preoperative thin slice temporal bone CT was adopted to obtain the images of the external auditory canal, stapes, incudostapedial joint, pyramidal eminence and posterior tympanic cavity. The widths of cartilaginous portion, isthmus and bony portion of the external auditory canal, the distance between stapes and pyramidal eminence and that between stapes and tympanic sinus, as well as the angle between the parallel line of long axis of talus cone and the extension line of stapes were observed and measured by Medical Systems software. The exposure difficulty of stapes was predicted preoperatively and confirmed intraoperatively. All the patients were divided into easily exposed group and difficultly exposed group according to the intraoperative difficulty of exposure. SPSS 17.0 software was used for statistical analysis.ResultsThe difficulty of stapes exposure was closely related to the distance from stapes to pyramidal eminence (P<0.01) and that between stapes and tympanic sinus (P<0.01), as well as the width of bony portion of external auditory canal (P<0.05). Meanwhile, the difficulty of stapes exposure was not related to the widths of cartilaginous portion and isthmus of external auditory canal, and the angle (α) (all P>0.05).ConclusionThe distance from stapes to pyramidal eminence and that between stapes and tympanic sinus have dramatic impact on exposure of stapes. The width of bony portion of external auditory canal may affect the difficulty of surgery. Parameters from preoperative highresolution CT of temporal bone may predict the difficulty of stapes exposure in ear microsurgery, which has certain practical value in clinical application.