title: Navigated transoral approach to the cranial base and the craniocervical junction: technical note.
abstract: OBJECTIVE
  The transoral approach is an elegant reliable surgical procedure that provides anterior exposure of the cranial base and the craniocervical junction. Our objective was to demonstrate the advantages of neuronavigation in planning and performing the transoral approach.
  
  
  METHODS
  Three patients with chordomas and one patient with rheumatoid atlantoaxial subluxation were considered for a neuronavigated transoral procedure. For image guidance, the Stryker navigation system (Stryker Instruments, Kalamazoo, MI) was used. Registration was performed with individually constructed occlusal splints with four markers.
  
  
  RESULTS
  The transoral approach was successfully used for two patients with chordomas involving the cranial base and the upper spine and for one patient with dislocation of the dens and medullary compression. In one case, preoperative simulation of the approach and trajectory planning demonstrated that adequate resection could not be achieved via the transoral route, and a paracondylar suboccipital approach was used. The registration accuracy achieved with the occlusal splint was less than 1 mm.
  
  
  CONCLUSIONS
  Neuronavigation is a useful tool for planning and performing a transoral approach. It optimizes preoperative planning, clarifies and secures resection limits, and reduces overall surgical morbidity. Registration with an occlusal splint with four markers proved to be an attractive alternative to conventional systems.
authors.affiliation: Department of Neurosurgery, Albrecht-Ludwigs University of Freiburg, Freiburg, Germany. wougio@nz.ukl.uni-freiburg.de
authors.forename: Vassilios I
authors.initials: VI
authors.lastname: Vougioukas
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hubbe
authors.forename: Jörg
authors.initials: J
authors.lastname: Schipper
authors.forename: Uwe
authors.initials: U
authors.lastname: Spetzger
mesh_terms: D000328:Adult; D001268:Atlanto-Axial Joint / Q000601:surgery; D002574:Cervical Vertebrae / Q000473:pathology / Q000601:surgery*; D002817:Chordoma / Q000175:diagnosis / Q000601:surgery*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation; D017090:Occlusal Splints; D009960:Oropharynx / Q000601:surgery; D012086:Reoperation; D019292:Skull Base Neoplasms / Q000175:diagnosis / Q000601:surgery*; D013123:Spinal Fusion; D013125:Spinal Neoplasms / Q000175:diagnosis / Q000601:surgery*