الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Cochlear implant is the established treatment for SNHL. The classical approach is the trans-mastoid facial recess till the present day. Its final aim is inserting electrode into the scala tympani. It has been judged by some authors to be affected by anatomical variations of the temporal bone. CT of the temporal bone can detect these difficulties with different measurement and non-measurement methods even in seemingly normal temporal bones. However, many methods were published in the literature regarding that matter and all with proposed statistical significance.This study was performed on 3 groups of patients, 65 adults with intra-operative comparison with statistical analysis, 82 pediatric CT scan with no comparison and 9 cadaveric specimens with dissection comparison without statistical analysis due to their small number.Assessment was done in 2 sections. First road map to RW assessing mastoid pneumatization, dural height, sigmoid sinus position and facial recess pneumatization. The second was the status of the round window area itself through assessing visibility of RWN through PT, RWM visibility through RWN and height of the jugular bulb CT could accurately predict all aspects of the road map. Classification of the RWN visibility had many measures applied to it in the literature and some of them in the present study. In our hands only one method was reliable. CT could predict RWM accessibility and anticipate if jugular bulb height can affect cochlear implant surgery.A pre-operative CT checklist was suggested to predict difficulties in CI through the classic approach and indicate when additional measures or alternative approaches might be necessary.