title: Present state and future perspectives of computer aided surgery in the field of ENT and skull base.
abstract: BACKGROUND
  CAS technology has emerged in the last 10 years and is more and more used for surgery of the anterior and lateral skull base. Endoscopic and microscopic CAS systems are available. The endoscopic key hole or minimal invasive procedure is used increasingly not only for treatment of inflammatory disease, but also for tumour surgery. The integration of CAS systems into these procedures raises the level of their safety and efficiency. In addition, they allow the distance to the bone border on the CT slices to be previewed and measured.
  
  
  OBJECTIVE
  Review of the present state of CAS systems, our own experience as a research centre and as users of the systems, demonstration of new navigational devices, microscope integration and a new registration procedure developed for the "Bernese" frameless optical navigation system (SurgiGATE ORL@1000, medivision, [Synthes, Stratec-medical], CH-4436 Oberdorf).
  
  
  METHODS
  The optical CAS system with microscope integration (VM 900@1000, Möller-Wedel, Germany), new devices and new matching procedure; accuracy tests on a cadaver skull and on the patient's head.
  
  
  RESULTS
  The practical accuracy on the cadaver skull with the pointer system has a mean average error of 0.79 mm, and the clinical accuracy is between 0.5 mm and 2 mm.
  
  
  CONCLUSIONS
  CAS-microscope integration, new CAS technical devices and new noninvasive CAS-registration procedures support the surgeon in more minimally invasive surgical procedures of the paranasal sinuses and the skull base. Future perspectives will be discussed.
authors.affiliation: Division of ENT, Head and Neck Surgery, Inselspital, University of Bern, Switzerland. marco.caversaccio@insel.ch
authors.forename: Marco
authors.initials: M
authors.lastname: Caversaccio
authors.forename: Lutz-Peter
authors.initials: LP
authors.lastname: Nolte
authors.forename: Rudolf
authors.initials: R
authors.lastname: Häusler
mesh_terms: D006801:Humans; D010038:Otorhinolaryngologic Diseases / Q000000981:diagnostic imaging* / Q000601:surgery*; D011859:Radiography; D015203:Reproducibility of Results; D019291:Skull Base / Q000000981:diagnostic imaging* / Q000601:surgery*; D025321:Surgery, Computer-Assisted / Q000295:instrumentation* / Q000379:methods / Q000639:trends*