Frameless optical computer-aided tracking of a microscope for otorhinology and skull base surgery

To integrate a digitally controlled operating microscope without a laser autofocus system into a frameless optical computer-aided surgery system and to test the accuracy and usability of this system in otorhinological surgery.

Experimental study and case series.

Department of Oto-Rhino-Laryngology, Head and Neck Surgery, Inselspital, and the Maurice E. Müller Institute for Biomechanics, University of Bern, Bern, Switzerland.

Eight computer-aided microscopic surgical procedures were performed between January and October 2000 on patients with various diseases of the anterior and lateral skull base.

The practical accuracy of the navigated microscope on the lateral side of a cadaver skull was 2.27 +/- 0.25 mm and on the anterior side of the same skull was 2.07 +/- 0.35 mm. In all 8 cases of computer-aided microscopic surgery, no complications occurred. Clinical inaccuracy was 2 to 3 mm.

Integration of a low-cost, non-laser autofocus microscope into our computer-aided surgery system was successfully performed and offers surgeons the ability to combine the precise optics of the operating microscope with the localization power of a computer-aided system.