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A stapedectomy is a surgical procedure of the middle ear performed to improve hearing. If the stapes footplate is fixed in position, rather than being normally mobile, then a conductive hearing loss results. There are two major causes of stapes fixation. The first is a disease process of abnormal mineralization of the temporal bone called otosclerosis. The second is a congenital malformation of the stapes. In both of these situations, it is possible to improve hearing by removing the stapes bone and replacing it with a micro prosthesis - a stapedectomy, or creating a small hole in the fixed stapes footplace and inserting a tiny, piston-like prosthesis - a stapedotomy. The results of this surgery are generally most reliable in patients whose stapes has lost mobility because of otosclerosis. Nine out of ten patients who undergo the procedure will come out with significantly improved hearing while less than 1% will experience worsened hearing acuity or deafness. Successful surgery usually provides an increase in hearing acuity of about 20 dB. That is as much difference as having your hands over both ears, or not. However, most of the published results of success fall within the speech frequency of 500 Hz, 1000 Hz and 2000 Hz; poorer results are typically obtained in the high frequencies, but these are normally less hampered by otosclerosis in the first place. ==Indications== Indications of stapedectomy: # Conductive hearing loss (due to fixation of stapes). # Air bone gap of at least 30 dB. # Presence of Carhart's notch in the audiogram of a patient with conductive hearing loss (relative) # Good cochlear reserve as assessed by the presence of good speech discrimination. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Stapedectomy」の詳細全文を読む スポンサード リンク
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