title: Calculation of an Optic Nerve Injury Risk Profile Before Sphenoid Sinus Surgery.
abstract: OBJECTIVE
  Our objective was to analyze variations in the optic nerve (ON) course and surrounding structures in an effort to construct an optic nerve injury risk profile before endoscopic intranasal sphenoidal, or endoscopic endonasal transphenoidal, skull-base surgery, and eventually to construct and formulate a common classification by combining the known classes. The authors used computed tomography (CT) toward this end.
  
  
  METHODS
  The authors retrospectively reviewed 200 consecutive CT scans (400 sides) of the paranasal sinuses. The pneumatization of the anterior clinoid process, the relationships of the ONs to the sphenoidal sinuses, and ON dehiscence were evaluated. The authors then created a formula by which risk profiles can be constructed for patients for whom sphenoid or parasellar surgery is planned.
  
  
  RESULTS
  Pneumatization of the anterior clinoid process was evident in 28.25%. Dehiscence of the bony wall of the ON was evident in 9.5%. The ON course lay adjacent to the sphenoidal sinus, causing sinus wall indentation, in 23%. Cumulative optic nerve injury risk scoring showed that, radiologically, surgery on 8.5% and 1.5% of sphenoid sinuses described here carried severe or critical risk of ON injury, respectively.
  
  
  CONCLUSIONS
  Head-and-neck surgeons and neurosurgeons should be aware of variations in ON course. The authors composed an optic nerve injury risk classification category based on the sum of individual weights of each of these classes. Reductions in ON injuries require careful evaluation of potential variant anatomies. Preoperative CT scans must be meticulously reviewed to avoid ON injury.
authors.affiliation: *ENT Department †Department of Diagnostic Radiology ‡Ophthalmology Department, Antalya Ataturk State Hospital §Department of Diagnostic Radiology, Antalya Training-Research Hospital, Antalya ||ENT Department, Medical Faculty, Kirikkale University, Kirikkale ¶ENT Department, Medical Faculty, Eskisehir Osmangazi University, Eskisehir, Turkey.
authors.forename: Erdem Atalay
authors.initials: EA
authors.lastname: Cetinkaya
authors.forename: Koray
authors.initials: K
authors.lastname: Koc
authors.forename: Mehmet Fatih
authors.initials: MF
authors.lastname: Kucuk
authors.forename: Pinar
authors.initials: P
authors.lastname: Koc
authors.forename: Nuray Bayar
authors.initials: NB
authors.lastname: Muluk
authors.forename: Cemal
authors.initials: C
authors.lastname: Cingi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D020221:Optic Nerve Injuries / Q000209:etiology / Q000517:prevention & control*; D010256:Paranasal Sinuses / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D011300:Preoperative Care; D012189:Retrospective Studies; D018570:Risk Assessment; D013101:Sphenoid Sinus / Q000601:surgery*; D055815:Young Adult