title: Limits of endoscopic visualization and instrumentation in the frontal sinus.
abstract: BACKGROUND
  Endoscopic limitations in the frontal sinus are poorly defined. We set out to define these limits.
  
  
  METHODS
  Fifteen cadaveric heads underwent endoscopic frontal sinusotomies (Draf IIA, IIB, III). Areas of frontal sinus openings were calculated. Coordinates of the most distant points for instrumentation, visualization, and instrumentation with visualization in the frontal sinus were identified with the use of image guidance.
  
  
  RESULTS
  Twenty-eight frontal sinuses were evaluated. The mean sinus opening areas were 47.5 mm2, 105.1 mm2, and 246.4 mm2 for Draf IIA, IIB, and III. Visualization exceeds instrumentation and visualized reach (P<0.05) regardless of different frontal sinusotomies. Anterior and lateral instrumentation and visualized reach increase as the frontal sinus opening increases (P<or=0.05). For lateral visualization, Draf III>IIB>IIA (P<0.04). There is no statistical difference for superior visualization, instrumentation, and visualized reach among various sinusotomies (P>0.05).
  
  
  CONCLUSIONS
  Endoscopic visualization exceeds instrumentation and instrumentation exceeds visualized reach. Enlarging frontal sinus opening area increases instrumentation and visualization.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Virginia Health System, Charlottesville, Virginia 22908-0713, USA.
authors.forename: Samuel S
authors.initials: SS
authors.lastname: Becker
authors.forename: Steven R
authors.initials: SR
authors.lastname: Bomeli
authors.forename: Charles W
authors.initials: CW
authors.lastname: Gross
authors.forename: Joseph K
authors.initials: JK
authors.lastname: Han
mesh_terms: D002102:Cadaver; D019723:Endoscopes; D004724:Endoscopy / Q000379:methods*; D005626:Frontal Sinus / Q000033:anatomy & histology* / Q000601:surgery; D006801:Humans; D016014:Linear Models