title: Variations of lamina papyracea position from the endoscopic view: a retrospective computed tomography analysis.
abstract: BACKGROUND
  Accidental injury of lamina papyracea (LP) remains one of the most common complications reported in endoscopic sinus surgery (ESS) even in most recent studies. The purpose of this study was to categorize the LP position radiologically and from an endoscopic perspective.
  
  
  METHODS
  A total of 207 computed tomography (CT) scans (414 sides) including both diseased and control groups were retrospectively reviewed by 2 examiners. Inferior turbinate attachment to the lateral nasal wall and the inferior margin of the planned middle meatal antrostomy (MMA) were identified anteriorly. Position of LP in relation to the vertical line passing through MMA inferior margin was reported. LP was categorized to lie either within 2 mm on either side of the MMA inferior margin (type I), more than 2 mm medial to the MMA line (type IIa: 2 to 4 mm; type IIb: >4 mm), or more than 2 mm lateral to the MMA line (type IIIa: 2 to 4 mm; type IIIb: >4 mm).
  
  
  RESULTS
  Of the 221 sides in the control group, 69.7% were classified as type I, 24.9% as type II, and 5.5% as type III. Among the 193 diseased operated sides examined, 60.1% were classified as type I, 20.2% as type II, and 13.5% as type III. Weighted kappa coefficient showed good interexaminer reliability. Five sides (2.6%) in the case group had accidental LP penetration intraoperatively, 4 of them were type II and type III LP.
  
  
  CONCLUSIONS
  This study improves surgeons' awareness of LP variations in the endoscopic field and can be of help for residents in training.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Faculty of Medicine, Zagazig University, Egypt; Ear, Nose, and Throat (ENT) Department, King Abdullah Medical City (KAMC), Makkah, Saudi Arabia.
authors.forename: Islam R
authors.initials: IR
authors.lastname: Herzallah
authors.forename: Osama A
authors.initials: OA
authors.lastname: Marglani
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Shaikh
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D004724:Endoscopy; D005004:Ethmoid Bone / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: allergic fungal sinusitis; anatomical types; chronic rhinosinusitis with nasal polyps; maxillary hypoplasia; medial orbital wall injury; orbit complication; paranasal sinuses anatomy; prevention of sinus surgery complications; radiologic classification; residual ethmoid cells