title: Petrous apex cholesterol granulomas: endonasal versus infracochlear approach.
abstract: OBJECTIVE
  The aim of this study was to investigate and compare the surgical anatomy of two different routes to access and drain petrous apex (PA) cholesterol granulomas: the expanded endonasal approach (EEA) and the transcanal infracochlear approach (TICA).
  
  
  METHODS
  Anatomic and radiologic study.
  
  
  METHODS
  The EEA and TICA to the PA were performed in 11 anatomic specimens with the assistance of imaging guidance. The PA was categorized into three zones: superior PA, anterior-inferior PA, and posterior-inferior PA. The maximum drainage window achieved by each approach was calculated using the imaging studies of each anatomic specimen.
  
  
  RESULTS
  The EEA was able to reach superior PA and anterior-inferior PA in all specimens and posterior-inferior PA in 90%. The TICA did not provide access to superior PA in any case. The TICA was suitable to reach anterior-inferior PA in 80% of specimens and posterior-inferior PA in 60%. Based on the radiologic study, the EEA provided a drainage window three times larger than the TICA.
  
  
  CONCLUSIONS
  The transnasal approach provides reliable access to the PA when combined with internal carotid artery exposure and allows for large drainage window. The transcanal approach is less versatile and more limited than the transnasal approach but provides access to the most posterior and inferior portion of the PA without Eustachian tube transection. Here we propose a new surgical classification that may help to decide the most suitable approach to the PA according to the location and extension of the lesion.
authors.affiliation: Department of Otolaryngology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Tiago Fernando
authors.initials: TF
authors.lastname: Scopel
authors.forename: Juan C
authors.initials: JC
authors.lastname: Fernandez-Miranda
authors.forename: Carlos D
authors.initials: CD
authors.lastname: Pinheiro-Neto
authors.forename: Maria
authors.initials: M
authors.lastname: Peris-Celda
authors.forename: Alessandro
authors.initials: A
authors.lastname: Paluzzi
authors.forename: Paul A
authors.initials: PA
authors.lastname: Gardner
authors.forename: Barry E
authors.initials: BE
authors.lastname: Hirsch
authors.forename: Carl H
authors.initials: CH
authors.lastname: Snyderman
mesh_terms: D002102:Cadaver; D002784:Cholesterol; D003051:Cochlea; D004322:Drainage / Q000379:methods*; D004724:Endoscopy / Q000379:methods*; D015745:Granuloma, Foreign-Body / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D006801:Humans; D008953:Models, Anatomic; D009666:Nose; D010579:Petrous Bone; D014057:Tomography, X-Ray Computed
chemical_list: D002784:Cholesterol