title: Identification of the internal carotid artery at the superior part of the cavernous sinus during endoscopic endonasal cavernous sinus tumor surgery.
abstract: BACKGROUND
  Identification of the internal carotid artery (ICA) is essential for successful endoscopic endonasal cavernous sinus tumor surgery. This study aimed to develop a method for identifying the ICA in cavernous sinus tumors at the superior part of the cavernous sinus.
  
  
  METHODS
  Ten fresh cadavers were studied with a 4-mm 0° and 30° endoscope to identify surgical landmarks of the ICA in the cavernous sinus. Clinical cases of cavernous sinus tumors were surgically treated using an endoscopic transpterygoid approach.
  
  
  RESULTS
  Anatomical study indicated the ICA at the superior part of the cavernous sinus can be identified using three steps: 1) exposure of the optic nerve sheath by drilling the optic canal; 2) identification of the proximal orifice of the optic nerve sheath at the transition of the optic nerve sheath and dura mater of the tuberculum sellae; and 3) identification of the clinoid segment of the ICA at the distal dural ring just below the proximal orifice of the optic nerve sheath. Although the ICA was encased and transposed by tumors in preliminary surgical cases, the clinoid segment of the ICA was safely exposed at the superior part of the cavernous sinus using this method.
  
  
  CONCLUSIONS
  Dural structures around the cavernous sinus are key to identifying the ICA at the superior part of the cavernous sinus. This method is expected to reduce the risk of ICA injury during endoscopic endonasal surgery for cavernous sinus tumors.
authors.affiliation: Department of Neurosurgery, Tokai University Hachioji Hospital, 1838 Ishikawa-machi, Hachioji, Tokyo, 192-0032, Japan, fuminarikomatsu@gmail.com.
authors.forename: Fuminari
authors.initials: F
authors.lastname: Komatsu
authors.forename: Masami
authors.initials: M
authors.lastname: Shimoda
authors.forename: Shinri
authors.initials: S
authors.lastname: Oda
authors.forename: Masaaki
authors.initials: M
authors.lastname: Imai
authors.forename: Hideaki
authors.initials: H
authors.lastname: Shigematsu
authors.forename: Mika
authors.initials: M
authors.lastname: Komatsu
authors.forename: Manfred
authors.initials: M
authors.lastname: Tschabitscher
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Matsumae
mesh_terms: D002102:Cadaver; D002343:Carotid Artery, Internal / Q000033:anatomy & histology*; D002426:Cavernous Sinus / Q000033:anatomy & histology*; D004210:Dissection / Q000379:methods*; D004388:Dura Mater / Q000033:anatomy & histology*; D004724:Endoscopy / Q000379:methods*; D006801:Humans; D008297:Male; D060787:Neoplasm Grading; D010255:Paranasal Sinus Neoplasms / Q000473:pathology* / Q000601:surgery*; D012658:Sella Turcica / Q000033:anatomy & histology