title: Lateral frontal sinus access in endoscopic skull-base surgery.
abstract: BACKGROUND
  The modified endoscopic Lothrop (MELP) or Draf III procedure can provide extended endoscopic access to the frontal sinus. The ability to access the entire frontal sinus entirely endoscopically is often debated and there is little published data to predict access based on tumor location.
  
  
  METHODS
  MELP was performed in 10 cadaver heads. Access was defined as the ability to contact the bone under vision with the head of a 70-degree diamond burr. Access was assessed in 3 areas: the orbital roof and the anterior and posterior walls of the frontal sinus. Endpoints were defined in millimeters from medial orbit and lateral quartile zones.
  
  
  RESULTS
  Complete lateral access was excellent anterior and posterior in 95% of sinuses (mean 15.5 ± 7.8 mm and 15.4 ± 7.7 mm, respectively). Access to the orbital roof was limited (10.3 ± 4.6 mm; p = 0.01 comparing anterior and posterior). For sinuses pneumatized beyond the midorbital point, only 10% of lateral orbital roofs were contacted. Orbital roof access correlated with the anteroposterior (AP) distance between the olfactory fossa and outer periosteum of the frontal beak (r = 0.6, p < 0.01).
  
  
  CONCLUSIONS
  Lateral endoscopic access to the walls of the frontal sinus is excellent except for the sinus floor. Access to the orbital roof is reliable in the medial quarter only and minimal lateral to the midorbital point. The ability to predict the areas accessible by the endoscopic approach and those areas that might require ancillary approaches is important for both surgical planning and patient expectations.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Concord General Hospital, Sydney, Australia. daniel.timperley@gmail.com
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Timperley
authors.forename: Catherine
authors.initials: C
authors.lastname: Banks
authors.forename: Daniel
authors.initials: D
authors.lastname: Robinson
authors.forename: Jason
authors.initials: J
authors.lastname: Roth
authors.forename: Raymond
authors.initials: R
authors.lastname: Sacks
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Harvey
mesh_terms: D000704:Analysis of Variance; D002102:Cadaver; D004724:Endoscopy / Q000379:methods*; D005626:Frontal Sinus / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D019291:Skull Base / Q000000981:diagnostic imaging / Q000601:surgery*; D014057:Tomography, X-Ray Computed