title: Measurements of the position relationship between the inferior margin of the oval window and the endosteum of basal cochlear turn in histologic and HRCT study.
abstract: OBJECTIVE
  To identify the optimum and safe location histologically for drilling and fenestration on promontory inferior to the oval window in stapedectomy. The value of application of high-resolution computed tomography (HRCT) scanning and multiple-planar reconstruction (MPR) for this purpose is also assessed.
  
  
  METHODS
  By means of histologic sections and HRCT scanning and MPR for coronal image, measurements were conducted on 3 perpendicular planes in temporal bone sections through the anterior, posterior, and midpoint of the inferior margin of the oval window, respectively.
  
  
  RESULTS
  The promontory bone inferior to the posterior portion of the oval window is thickest, which has an average thickness of about 1.1 mm. The endosteum of the basal turn here is deepest under the promontory, which has an average height of about 0.2 mm above the plane of footplate, whereas the distance between the inferior margin of the oval window and the endosteum here is no more than 0.3 mm. The coincidence rate of the measurements by HRCT and histology is up to 90.5%.
  
  
  CONCLUSIONS
  Relatively safe location for bone of the promontory removal should be restricted in the posterior portion inferior to the oval window, and the burr should be lifted laterally while drilling. Preoperative HRCT scanning and MPR for coronal image would offer a valuable reference to estimate the safe area for bone of the promontory removal in stapedectomy.
authors.affiliation: Department of Otolaryngology Head and Neck Surgery, Sun Yat-Sen Memorial Hospital, Guangzhou, People's Republic of China.
authors.forename: Yubin
authors.initials: Y
authors.lastname: Chen
authors.forename: Suijun
authors.initials: S
authors.lastname: Chen
authors.forename: Yu
authors.initials: Y
authors.lastname: Si
authors.forename: Yi
authors.initials: Y
authors.lastname: Liu
authors.forename: Hao
authors.initials: H
authors.lastname: Xiong
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D003051:Cochlea / Q000033:anatomy & histology / Q000601:surgery*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D010040:Otosclerosis / Q000601:surgery*; D010046:Oval Window, Ear / Q000033:anatomy & histology / Q000601:surgery*; D013201:Stapes Surgery / Q000379:methods*