title: Three-dimensional and 2-dimensional endoscopic exposure of midline cranial base targets using expanded endonasal and transcranial approaches.
abstract: OBJECTIVE
  Endoscopic endonasal approaches provide an access method to the midline cranial base. To integrate these approaches into neurosurgical practice, the extent of their anatomic exposure must be compared with that provided by more traditional transcranial approaches.
  
  
  METHODS
  Ten fresh cadaver heads were studied. Both endonasal and transcranial approaches to the midline cranial base were performed. The midline cranial base was divided into several areas, and the relative exposure provided by each approach was described and presented in both 2-dimensional and 3-dimensional images. Limitations and advantages of each approach are discussed.
  
  
  RESULTS
  The endonasal approaches achieved a direct and wide exposure of the midline extracranial and intracranial cranial base anatomy. The main lateral limitations of the endonasal approaches were the optic nerves, lateral cavernous sinus, vidian nerve, internal carotid artery, abducens nerve in Dorello's canal, jugular tubercle, and hypoglossal canals. Limitations of the transcranial approaches were the neurovascular structures which lie in the operative corridor and create narrow working spaces.
  
  
  CONCLUSIONS
  The endonasal approaches achieve a direct and wide exposure of the midline cranial base bilaterally. Lateral exposure, beyond the cranial nerves and carotid artery, are challenging. Transcranial approaches are limited by the narrow corridors provided by the cranial nerves, and they do not visualize the contralateral paramedian cranial base very well. Three-dimensional endoscopes augment the spatial orientation and may improve patient safety and the learning curve for endoscopic approaches to the midline cranial base.
authors.affiliation: Department of Neurological Surgery, Weill Medical College of Cornell University, New York Presbyterian Hospital, New York, New York 10021, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Roth
authors.forename: Ameet
authors.initials: A
authors.lastname: Singh
authors.forename: Gurston
authors.initials: G
authors.lastname: Nyquist
authors.forename: Justin F
authors.initials: JF
authors.lastname: Fraser
authors.forename: Antonio
authors.initials: A
authors.lastname: Bernardo
authors.forename: Vijay K
authors.initials: VK
authors.lastname: Anand
authors.forename: Theodore H
authors.initials: TH
authors.lastname: Schwartz
mesh_terms: D002102:Cadaver; D004724:Endoscopy / Q000379:methods*; D006801:Humans; D009296:Nasal Cavity / Q000033:anatomy & histology / Q000601:surgery*; D019635:Neurosurgical Procedures / Q000379:methods*; D019291:Skull Base / Q000033:anatomy & histology / Q000601:surgery*