title: Usefulness of the radiological planning for hearing preservation surgery in vestibular schwannoma.
abstract: OBJECTIVE
  During vestibular schwannoma surgery there is a risk of endolymphatic duct and sac injury, which may cause a loss or a deterioration of hearing. The goal of the study was to evaluate the empirical utility of presurgical planning using CT with the bone window for the hearing preservation surgery.
  
  
  METHODS
  The study was performed on 14 human temporal bones. CT scans with the bone window were obtained in the standard position. Safe drilling line was evaluated and after that drilling distances were analysed: the lateral drilling distance, total length of internal acoustic meatus, drilled length of internal acoustic meatus. After this, a surgical exposure was performed, using size of a drill tip as measuring scale. The dura was excised and endolymphatic duct was injected with a latex. Revision of the internal acoustic meatus was performed with the use of a microscope.
  
  
  RESULTS
  Mean results of safe drilling coefficients were: lateral drilling distance: 10 ± 2 mm, total length of internal acoustic meatus: 9 ± 2 mm, drilled length of internal acoustic meatus: 7 ± 2 mm. In all cases, no endolymphatic duct injury was observed.
  
  
  CONCLUSIONS
  Preoperative radiological planning using the safe drilling coefficients is of value for the hearing preservation surgery in vestibular schwannoma. The size of the drilling tip may be used as an intraoperative measuring scale during this procedure. However, CT with a bone window is a necessary tool for the purposes of this procedure.
authors.affiliation: Department of Descriptive and Clinical Anatomy, Medical University of Warsaw, Chałubińskiego 5, Warsaw, 02-004, Poland. kamil.krystkiewicz@gmail.com.
authors.forename: Kamil
authors.initials: K
authors.lastname: Krystkiewicz
authors.affiliation: Department of Descriptive and Clinical Anatomy, Medical University of Warsaw, Chałubińskiego 5, Warsaw, 02-004, Poland.|Department of Pediatric Neurosurgery, Bogdanowicz Memorial Hospital for Children, Warsaw, Poland.
authors.forename: Tymon
authors.initials: T
authors.lastname: Skadorwa
authors.affiliation: Department of Descriptive and Clinical Anatomy, Medical University of Warsaw, Chałubińskiego 5, Warsaw, 02-004, Poland.|1st Department of Clinical Radiology, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Paweł
authors.initials: P
authors.lastname: Szaro
authors.affiliation: Department of Descriptive and Clinical Anatomy, Medical University of Warsaw, Chałubińskiego 5, Warsaw, 02-004, Poland.|Department of Pediatric Neurosurgery, Bogdanowicz Memorial Hospital for Children, Warsaw, Poland.
authors.forename: Bogdan
authors.initials: B
authors.lastname: Ciszek
mesh_terms: D006801:Humans; D009464:Neuroma, Acoustic / Q000000981:diagnostic imaging / Q000601:surgery*; D011300:Preoperative Care; D014057:Tomography, X-Ray Computed
keywords: Endolymphatic duct; Endolymphatic sac; Hearing preservation surgery; Retrosigmoid approach; Vestibular schwannoma