This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anatomy of Middle Ear (Otitis Media), Subject name: ENT
[{'content': 'A 30-year-old male is having attic cholesteatoma of left ear with lateral sinus thrombophlebitis. Which of the following will be the operation of choice: \nSelect and explain. \nA. Intact canal wall mastoidectomy, B. Simple mastoidectomy with tympanoplasty, C. Canal wall down mastoidectomy, D. Mastoidectomy with cavity obliteration', 'role': 'user'}, {'content': 'Answer: C \nExplanation: (c) Canal wall down mastoidectomy(Ref. Cummings, 6th ed., 2175)Intact canal wall down mastoidectomy is done when there is limited disease in the mastoid.Simple mastoidectomy also known as cortical mastoidectomy is done for acute and coalescent mastoiditis.Following any canal wall down procedure the big mastoid cavity can be obliterated to prevent cavity related problems but if the unsafe CSOM is associated with complications this is postponed to a next stage.', 'role': 'assistant'}]