title: Decision making for the surgical approach of posterior petrous bone meningiomas.
abstract: OBJECTIVE
  The authors undertook this study to examine the surgical approaches used to treat posterior petrous bone meningiomas at a single institution and retrospectively evaluate their surgical strategy based on a previously published classification.
  
  
  METHODS
  Cases in which craniotomies were performed to treat posterior petrous bone meningiomas between 2002 and 2010 were retrospectively reviewed. Data were examined from 57 patients who were treated for 59 tumors. The tumors were classified into 3 types according to the location of their primary dural attachment: Type A, located around the porus trigeminus (33 tumors); Type M, located at the level of the porus of the internal auditory canal (IAC) (12 tumors); and Type P, located laterally to the IAC (14 tumors). The median tumor diameter was 34 mm (range 20-67 mm).
  
  
  RESULTS
  The choice of the approach was based on tumor location, as the displacement of vascular structures and cranial nerves was primarily determined by the site of dural attachment on the posterior petrous bone. An anterior petrosectomy was performed in 82% of Type A meningiomas, and a retrosigmoid approach was used in 86% of Type P meningiomas. The spectrum of approaches was less uniform for Type M meningiomas. Overall, total resection was obtained in 39% of all cases, and in 18%, 50%, and 86% of Type A, Type M, and Type P tumors, respectively. The postoperative mortality rate was 8.8% (5 deaths among 57 patients), and all 5 patients who died during the early postoperative period had large Type A tumors. At last follow-up, the functional preservation of the facial nerve was excellent in 49 (94%) of the 52 surviving patients.
  
  
  CONCLUSIONS
  The authors believe that proper selection of the approach favorably impacts functional outcome in patients undergoing surgery for the treatment of skull base tumors. In the authors' case series of posterior petrous bone meningiomas, Type P and most Type M tumors were safely managed through a regular retrosigmoid approach, whereas Type A tumors were optimally treated via an epidural anterior petrosectomy.
authors.affiliation: CHU Marseille Nord APHM, Université de la Méditerrannée, Chemin des Bourelly, Marseille Cedex 20, France. proche@ap-hm.fr
authors.forename: Pierre-Hugues
authors.initials: PH
authors.lastname: Roche
authors.forename: Vincent
authors.initials: V
authors.lastname: Lubrano
authors.forename: Rémy
authors.initials: R
authors.lastname: Noudel
authors.forename: Anthony
authors.initials: A
authors.lastname: Melot
authors.forename: Jean
authors.initials: J
authors.lastname: Régis
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003389:Cranial Nerve Diseases / Q000209:etiology; D003657:Decision Making; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000473:pathology / Q000601:surgery*; D008579:Meningioma / Q000473:pathology / Q000601:surgery*; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D010579:Petrous Bone / Q000601:surgery*; D011183:Postoperative Complications; D016634:Radiosurgery / Q000379:methods; D012189:Retrospective Studies