A retrospective analysis of 10 patients was performed to evaluate navigation systems in extranasal frontal skull base surgery. When performing a craniotomy following a bicoronal skin incision, the surgeon has to calculate the extent of the frontal sinus to avoid unnecessary damage to the dura or mucoceles later. Due to surgical morbidity including compression of the frontal lobe, many skull base surgeons have refused to use such an approach. Malformation or bone-destruction complicates the identification of the borders and increases the risk ofside-effects. Navigation systems can be an alternative for calculating the frontal sinus outlines during surgery. In the authors’ surgical procedure two different navigation systems were used. Conventional surgery using the transfrontal, transbasal or subcranial approach consisting of trepanation and craniotomy were performed, while the navigated surgical procedure was evaluated.

The analysis showed that computer-assisted surgery (CAS) is applicable to extranasal frontalskull base surgery. In comparison to X-ray beam-controlled craniotomy, CAS is beneficial as it constitutes a noninvasive instrument of quality management. Furthermore, the analysis indicatedthat under the guidance of a navigation system a precise pre-surgical simulation is available in order to perform an optimal craniotomy and reconstruction of the frontal skull base.

This cadaver study assessed the value of navigation in cochlear implant surgery. Cochlear implantation was simulated on a cadaver using a Stryker-Leibinger navigation system and a Nucleus 24 Contour implant. A conventional surgical strategy consisting of mastoidectomy, posterior tympanotomy, and cochleostomy was performed. The navigated surgical procedure was evaluated for accuracy, reliability, reproducibility, and practicability. The technology of computer-assisted surgery is applicable in cochlear implantation and beneficial in as much as the navigation-controlled implantation constitutes a non-invasive instrument of quality management. Nevertheless, in order to keep the point accuracy below one millimeter, a referencing methodusing concealed bordering anatomical structures may be further needed to perform the cochleostomy reliably under the guidance of a navigation system. More reproducible reference systems are needed if navigated lateral skull base surgery is to be fully relied upon.

Three-dimensional computer-aided surgery adds a ‘third-dimension’ to endoscopic sinus surgery. The images it provides have the potential to provide the surgeon with further information that might result in safer and more effective surgery with less surgical morbidity. The gold test, as yet untested, will be whether the technique leads to fewer revision procedures and complications as a result of more complete and safe initial surgery. Its greatest asset lies in reinforcing the surgeons’ estimate of an instrument’s position in a difficult anatomical area. It can augment the learning curve and enhance teaching and training in endoscopic sinus surgery but it is not a substitute for a thorough knowledge of paranasal sinus anatomy.