title: Surgical consideration to optic nerve protrusion according to sinus computed tomography.
abstract: OBJECTIVE
  This study aimed to investigate the prevalence of optic nerve protrusion (ONP) and its clinical indicators by using sinus computed tomography (CT) scan.
  
  
  METHODS
  Sinus CT scans of 260 consecutive patients with chronic inflammatory sinus disease were reviewed.
  
  
  RESULTS
  The prevalence of ONP in our study population was 28%. Nineteen percent of the optic nerves protruded into the sphenoid sinuses including indentation of the sinus wall (12%) and coursing through the sphenoid sinus (8%). In the presence of contralateral ONP and/or ipsilateral anterior clinoid process pneumatization, the chance of ONP occurrence was significantly higher (both P < 0.01). They were reliable indicators of ONP (R(2) = 0.47, P < 0.01).
  
  
  CONCLUSIONS
  ONP is a common anatomic variation observed in patients with chronic inflammatory sinus disease. To reduce optic nerve damage in surgeries, the presence of ONP according to sinus CT scans and the intraoperative findings should be carefully evaluated.
  
  
  METHODS
  C-4.
authors.affiliation: Department of Otolaryngology, Chang Gung Memorial Hospital, Taipei, Taiwan, Republic of China.
authors.forename: Ying-Lin
authors.initials: YL
authors.lastname: Chen
authors.forename: Li-Ang
authors.initials: LA
authors.lastname: Lee
authors.forename: Kun-Eng
authors.initials: KE
authors.lastname: Lim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001847:Bone Diseases / Q000000981:diagnostic imaging; D002908:Chronic Disease; D005005:Ethmoid Sinus / Q000000981:diagnostic imaging / Q000294:innervation; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D009900:Optic Nerve / Q000000981:diagnostic imaging*; D009901:Optic Nerve Diseases / Q000000981:diagnostic imaging; D020221:Optic Nerve Injuries / Q000517:prevention & control; D011391:Prolapse; D012189:Retrospective Studies; D012737:Sex Factors; D013100:Sphenoid Bone / Q000000981:diagnostic imaging / Q000294:innervation; D013101:Sphenoid Sinus / Q000000981:diagnostic imaging / Q000294:innervation* / Q000601:surgery; D015524:Sphenoid Sinusitis / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed