الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Cochlear implantation (CI) is typically performed through a mastoidectomy and posterior tympanotomy approach. The electrode array is inserted via the round window or a cochleostomy. The surgical procedure can be modified if necessary in order to obtain adequate surgical exposure. Preoperative high-resolution computed tomography (HRCT) of the temporal bone demonstrates the anatomical features and can predict the difficulty of the surgical approach.
Successful implantation via the posterior tympanotomy approach depends upon accurate identification of the round window niche (RWN), which can be difficult in patients with limited RWN visibility. Therefore, it is beneficial for surgeons to be able to predict RWN visibility preoperatively. Posterior tympanotomy through facial recess (FR) is the conventional and most preferred approach to facilitate cochlear implantation, especially when the electrode is inserted through the round window. The complications of the FR approach can be minimized by proper understanding of the anatomy of the FR.
The aim of this study is to measure the facial recess (width and length) radiologically and correlate this measurement with the surgical measurement in the cochlear implantation.
The current study is an observational cross sectional study, 100 participants were enrolled for this study (56 female and 44 male). Facial recess width was measured from anterolateral surface of the facial nerve to the posterior canaliculus of the chorda tympani nerve passing through the chorda tympani nerve (maximum width), it was measured in axial cut, oblique sagittal plane and curved MPR CT. Facial recess length was measured from the most superior point beneath the lateral semicircular
Summary
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canal to the chorda tympani branching point in oblique sagittal plane and curved MPR CT. facial nerve position was determined.
In our study there was statistically significant correlation between FR width clinical and FR width radiology, and FR width measured in the axial cut, curved MPR CT and oblique sagittal cut can predict FR width clinical, and curved MPR CT was the most statistically significant one that can predict FR width .there was there was statistically significant correlation between FR length clinical and FR length radiology.
There was no statistically significant difference between axial cut and curved MPR CT as regard mean of FR width (mm). There was no statistically significant difference between oblique sagittal and curved MPR CT as regard FR length (mm). There was easy round window accessibility in 78% of patients, difficult round window accessibility in 18% of patients and inaccessible round window in 4% of patients.