title: Experimental Endoscopic Angular Domains of Transnasal and Transoral Routes to the Craniovertebral Junction: Light and Shade.
abstract: METHODS
  We investigate on the surgical reliability of nasal palatine line for the transnasal approach and introduce a conceptually analogue radiological line as a reliable predictor of the maximal superior extension of the transoral approach. We have also compared radiological and surgical lines to find possible radiological references points to predict preoperatively the maximal extent of superior dissection for the transoral approach.
  
  
  OBJECTIVE
  After comparing the surgical exposition angle and the working channel volume of both the approaches in our previous article, now we compare the radiological (theoretical) with the "surgical" (effective) Nasopalatine line and the latter with the recently introduced Nasal Axial Line. We conceived a radiological line with a similar significance for the transoral approach and we called it Mandibulopalatine line; then we compared the radiological with the "surgical" one.
  
  
  BACKGROUND
  Endoscopy represents both an alternative and a useful complement to the standard microsurgical approach to the anterior craniovertebral junction (CVJ). Both the surgical routes have a limitation caused by the hard palate.
  
  
  METHODS
  Ten fresh nonperfused cadavers were studied. Transnasal and transoral linear and angled exposure of the CVJ were evaluated by means of X-ray and CT scan in the sagittal plane.
  
  
  RESULTS
  The angular difference between the radiological and surgical transoral endoscopic lines was significantly smaller compared with the difference between the radiological and surgical transnasal lines. Finally we found how to calculate preoperatively the "surgical" (effective) Mandibulopalatine line by a simple lateral preoperative radiological study of the CVJ.
  
  
  CONCLUSIONS
  Naso-axial line is confirmed to be a reliable preoperative predictor of the maximal extent of inferior dissection for transnasal approach. Surgical Palatine Inferior dental Arch line will draw the maximal extent of superior dissection for the transoral approach with simple lateral head X-ray examination by open mouth.
  
  
  METHODS
  3.
authors.affiliation: *Institute of Neurosurgery, Catholic University of Rome, Rome, Italy †Institute of Radiology, Catholic University of Rome, Rome, Italy ‡Institute of Otolaryngology, Catholic University of Rome, Rome, Italy.
authors.forename: Masimiliano
authors.initials: M
authors.lastname: Visocchi
authors.forename: Gaetano
authors.initials: G
authors.lastname: Pappalardo
authors.forename: Marco
authors.initials: M
authors.lastname: Pileggi
authors.forename: Francesco
authors.initials: F
authors.lastname: Signorelli
authors.forename: Gaetano
authors.initials: G
authors.lastname: Paludetti
authors.forename: Giuseppe
authors.initials: G
authors.lastname: La Rocca
mesh_terms: D000328:Adult; D000368:Aged; D001269:Atlanto-Occipital Joint / Q000000981:diagnostic imaging / Q000601:surgery; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009055:Mouth / Q000000981:diagnostic imaging / Q000601:surgery; D009296:Nasal Cavity / Q000000981:diagnostic imaging / Q000601:surgery; D057605:Natural Orifice Endoscopic Surgery / Q000379:methods*; D021362:Palate, Hard / Q000000981:diagnostic imaging / Q000601:surgery; D012886:Skull / Q000000981:diagnostic imaging / Q000601:surgery; D014057:Tomography, X-Ray Computed