title: Quantitative analysis of exposure of staged orbitozygomatic and retrosigmoid craniotomies for lesions of the clivus with supratentorial extension.
abstract: OBJECTIVE
  A two-stage approach using orbitozygomatic (OZ) and retrosigmoid (RS) craniotomies is one option for the management of petroclival lesions with supratentorial extension. The goal of this study was to investigate the supratentorial and infratentorial exposures of the clivus obtained through this staged approach.
  
  
  METHODS
  Formalin-fixed, silicon-injected specimens underwent stereotactic imaging. Six paired OZ and RS craniotomies were performed. Neuronavigation was used to determine the areas and limits of exposure and to plot these areas on three-dimensional reconstructions of the skull base.
  
  
  RESULTS
  The mean area of exposure of the parasellar region and clivus through the OZ craniotomy was 640 +/- 75 mm. Visualization of the parasellar region, cavernous sinus, and upper cranial nerves was achieved. The ventral brainstem corresponding to the cranial quarter of the clivus was visualized. The mean area of exposure of the clivus and petrous bone through the RS was 1930 +/- 250 mm. In the cranial quarter of the clivus, there was a small region of overlap in exposure between the two craniotomies. The limits of exposure are described.
  
  
  CONCLUSIONS
  OZ and RS craniotomies provide complementary exposure with limited redundancy. Significant visualization of the parasellar region, clivus, and surrounding bony landmarks is obtained. The primary limitation is exposure of the contralateral half of Zones II and III of the clivus. This strategy represents a reasonable option for accessing paracentral petroclival lesions with a supratentorial extension.
authors.affiliation: Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Little
authors.forename: Pakrit
authors.initials: P
authors.lastname: Jittapiromsak
authors.forename: Neil R
authors.initials: NR
authors.lastname: Crawford
authors.forename: Pushpa
authors.initials: P
authors.lastname: Deshmukh
authors.forename: Mark C
authors.initials: MC
authors.lastname: Preul
authors.forename: Robert F
authors.initials: RF
authors.lastname: Spetzler
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Bambakidis
mesh_terms: D001932:Brain Neoplasms / Q000473:pathology / Q000601:surgery*; D003399:Craniotomy / Q000379:methods*; D006801:Humans; D009915:Orbit / Q000473:pathology / Q000601:surgery*; D019292:Skull Base Neoplasms / Q000473:pathology / Q000601:surgery*; D015050:Zygoma / Q000473:pathology / Q000601:surgery*