الفهرس 
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Abstract
Mastoidectomy and posterior tympanotomy (PT) are cochlear implantation (CI) cornerstones. This approach is still the most used by otologists. Many anatomical variations may affect these surgical steps and increase surgical difficulty and complications liability. So, we proposed a numerical radiological scoring system that included most of the previously used parameters with other novel parameters covering all the aspects related to mastoidectomy and posterior tympanotomy difficulties during cochlear implantation.
It was a multicenter prospective case-series study from October 2021 to April 2022. We included 73 CI candidates through the PT approach. The radiological score, composed of thirteen items with a twenty-point total score, was fulfilled and evaluated before each CI surgery independently by two physicians. This radiological score covered many aspects such as the FN localization, second genu angle, PT width. PT depth, FR aeration, CF angle, CF-SM length, middle ear opacification, sigmoid sinus location, tegmen level, the presence of the Korner′s septum, and the mastoid aeration. We used verified radiological methods for the radiological evaluation or verified novel methods. Then, we correlated this score with the intraoperative difficulty and surgical duration.
The operation was straightforward in 42 patients with a score of 3.87 ± 1.725 and challenging in 31 patients with a score of 10.66 ± 1.73. The radiological score was strongly correlated with the surgical difficulty and duration (P-value <0.0001). Chorda-facial angle, MPFN localization in the medial-to-lateral direction, and facial recess aeration were the most independent variables that significantly affected the score. A score of more than 7.5 was associated with surgical difficulty. This cut-off point was highly sensitive (96.8%), specific (100%), and accurate (98.63%).