title: Petrous bone pneumatization is a risk factor for cerebrospinal fluid fistula following vestibular schwannoma surgery.
abstract: BACKGROUND
  For the prevention of postoperative CSF fistula a better understanding of origins and risk factors is necessary.
  
  
  OBJECTIVE
  To identify the petrous bone air cell volume as a risk factor for developing CSF fistula, we performed a retrospective analysis.
  
  
  METHODS
  From 2000 to 2007 519 patients had a retrosigmoidal surgical removal of a vestibular schwannoma. The 22 who had a postoperative CSF fistula were chosen for evaluation in addition to 78 patients who were randomly selected in 4 equally sized cohorts: male/female with small/large tumors. Preoperative CT scans were analyzed regarding petrous bone air cell volume, area of visible pneumatization at the level of the internal auditory canal (IAC), tumor grade, and sex.
  
  
  RESULTS
  : Women developed nearly half as many CSF fistulas (2.7%) as men (5.2%). The mean volume of the petrous bone air cells was 10.97 mL (SD, 4.9; range, 1.38-27.25). It was significantly lower for women (mean, 9.23 mL; SD, 3.8) than for men (mean, 12.5 mL; SD, 5.28; P = .0008). The mean air cell volume of CSF-fistula patients was 13.72 mL (SD, 5.22). The difference concerning the air cell volume between patients who developed CSF fistulas and patients from the control group was significant (P = .0042). There was a significant positive correlation between the air cell volume and the area of pneumatization in one CT slide at the level of the IAC.
  
  
  CONCLUSIONS
  The higher incidence of CSF fistulas in men compared with women can be explained by means of differently pneumatized petrous bones. A high amount of petrous bone pneumatization has to be considered as a risk factor for the development of postoperative CSF fistula after vestibular schwannoma surgery.
authors.affiliation: Department of Neurosurgery, University Hospital of Bern, Bern, Switzerland. Lennart@Stieglitze.de
authors.forename: Lennart Henning
authors.initials: LH
authors.lastname: Stieglitz
authors.forename: Mario
authors.initials: M
authors.lastname: Giordano
authors.forename: Venelin
authors.initials: V
authors.lastname: Gerganov
authors.forename: Andreas
authors.initials: A
authors.lastname: Raabe
authors.forename: Amir
authors.initials: A
authors.lastname: Samii
authors.forename: Madjid
authors.initials: M
authors.lastname: Samii
authors.forename: Wolf Olaf
authors.initials: WO
authors.lastname: Lüdemann
mesh_terms: D000328:Adult; D000368:Aged; D065634:Cerebrospinal Fluid Leak; D002559:Cerebrospinal Fluid Rhinorrhea / Q000209:etiology* / Q000517:prevention & control; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000601:surgery*; D010579:Petrous Bone / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000601:surgery*; D011183:Postoperative Complications / Q000209:etiology*; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors