title: Anatomic comparison of anterior petrosectomy versus the expanded endoscopic endonasal approach: interest in petroclival tumors surgery.
abstract: OBJECTIVE
  Since the petroclival region is deep-seated with close neurovascular relationships, the removal of petroclival tumors still represents a fascinating surgical challenge. Although the classical anterior petrosectomy (AP) offers a meaningful access to this petroclival region, the expanded endoscopic endonasal approach (EEEA) recently leads to overcome difficulties from trans-cranial approaches. Herein, we present an anatomic comparison of AP versus EEEA. We aim to describe the limits of these both approaches helping the choice of the optimal surgical route for petroclival tumors.
  
  
  METHODS
  Six fresh cadaveric heads were harvested and injected with colored latex. Each approach was step-by-step detailed until its final surgical exposure.
  
  
  RESULTS
  The AP provided a narrow direct supero-lateral access to the petroclival area that can also reach the cavernous sinus, the retrochiasmatic region and perimesencephalic cisterns. However, this corridor anterior to the internal acoustic meatus passed on each side of the trigeminal nerve. Moreover, tumor extensions toward the foramen jugularis, inside the clivus or behind the internal acoustic meatus were difficult to control. The EEEA brought a straightforward access to the clivus but the petrous apex was hidden behind the internal carotid artery. Several variants were described: a medial transclival, a lateral through the Meckel's cave and an inferior trans-pterygoid route. Elsewhere, tumor extension behind the internal acoustic meatus or above the tentorium could not be satisfactorily assessed.
  
  
  CONCLUSIONS
  PA and EEEA have their own limits in reaching the petroclival region in accordance with the tumor characteristics. The AP should be preferred for radical removal of middle-sized petrous apex intradural tumors like meningiomas. The EEEA would be of interest for extradural midline tumors like chordomas or for petrous apex cysts drainage.
authors.affiliation: Skull Base Multi-disciplinary Unit, Department of Neurosurgery B, Neurological Hospital Pierre Wertheimer, Hospices Civils de Lyon, 59 Bd Pinel, 69677, Lyon Cedex, France. timothee.jacquesson@neurochirurgie.fr.|Department of Anatomy, University of Lyon 1, 8 Avenue Rockefeller, 69003, Lyon, France. timothee.jacquesson@neurochirurgie.fr.
authors.forename: Timothée
authors.initials: T
authors.lastname: Jacquesson
authors.affiliation: Department of Anatomy, University of Lyon 1, 8 Avenue Rockefeller, 69003, Lyon, France.
authors.forename: Emile
authors.initials: E
authors.lastname: Simon
authors.affiliation: Skull Base Multi-disciplinary Unit, Department of Neurosurgery B, Neurological Hospital Pierre Wertheimer, Hospices Civils de Lyon, 59 Bd Pinel, 69677, Lyon Cedex, France.
authors.forename: Moncef
authors.initials: M
authors.lastname: Berhouma
authors.affiliation: Skull Base Multi-disciplinary Unit, Department of Neurosurgery B, Neurological Hospital Pierre Wertheimer, Hospices Civils de Lyon, 59 Bd Pinel, 69677, Lyon Cedex, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Jouanneau
mesh_terms: D002102:Cadaver; D003388:Cranial Fossa, Posterior / Q000601:surgery; D004724:Endoscopy; D006801:Humans; D019635:Neurosurgical Procedures / Q000379:methods*; D010579:Petrous Bone / Q000601:surgery*; D012888:Skull Neoplasms / Q000601:surgery*
keywords: Endonasal; Endoscopy; Petroclival; Petrosectomy; Skull base