title: Intradural en-bloc removal of the anterior clinoid process.
abstract: BACKGROUND
  Anterior clinoidectomy is useful in the surgical treatment of paraclinoid and parasellar lesions. Previously reported procedures require expertise in drilling, the alternative method reported here reduces the drilling procedure.
  
  
  RESULTS
  En-bloc clinoidectomy is performed intradurally via the standard pterional approach. A 1 to 2 mm-wide narrow drill line is placed with a 1 mm-wide diamond burr through the lesser sphenoid wing. It encircles the medial border of the optic canal and the lateral border of the lesser sphenoid wing over the superior orbital fissure, and is located about 1 cm anterior to the posterior margin of the optic canal. After drilling, one bony piece that includes the anterior clinoid process (ACP) and the optic canal roof remains connected to the basisphenoid bone by the optic strut alone. The optic strut is then fractured easily by applying leverage near its junction with the basisphenoid bone and the piece is removed en bloc with the major part of the optic strut, requiring little or no additional drilling of the residual bony fragments. Of 37 patients who underwent our en-bloc clinoidectomy, only one suffered complications consisting of cerebrospinal fluid (CSF) leakage through the sphenoid sinus. Our procedure requires an average of 20 min.
  
  
  CONCLUSIONS
  Intradural en-bloc removal of the ACP with fracture of the optic strut requires minimal drilling, resulting in decreased risk of injury to the optic nerve and a shortened time for clinoidectomy.
authors.affiliation: Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto, Japan. jat@kuhp.kyoto-u.ac.jp
authors.forename: J A
authors.initials: JA
authors.lastname: Takahashi
authors.forename: A
authors.initials: A
authors.lastname: Kawarazaki
authors.forename: N
authors.initials: N
authors.lastname: Hashimoto
mesh_terms: D004388:Dura Mater / Q000601:surgery*; D006801:Humans; D002532:Intracranial Aneurysm / Q000601:surgery; D020221:Optic Nerve Injuries / Q000517:prevention & control; D009915:Orbit / Q000601:surgery; D010027:Osteotomy / Q000379:methods*; D010911:Pituitary Neoplasms / Q000601:surgery; D013100:Sphenoid Bone / Q000601:surgery*