This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
[{'content': 'Which of the following surgery is known as Schwaz operation? \nSelect and explain. \nA. Coical mastoidectomy, B. Radical mastoidectomy, C. Modified radical mastoidectomy, D. Myringotomy', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Coical mastoidectomy, known as simple or complete mastoidectomy or Schwaz operation, is complete exenteration of all accessible mastoid air cells and conveing them into single cavity. Posterior meatal wall is left intact. Middle ear structures are not disturbed. Indications: 1. Acute coalescent mastoiditis 2. Incompletely resolved acute otitis media with reservoir sign 3. Masked mastoiditis 4. As an initial step to perform, Endolymphatic sac surgery Decompression facial nerve Translabyrinthine or retrolabyrinthine procedures for acoustic neuroma', 'role': 'assistant'}]