Neuronavigation System as a Tool for the Treatment of Skull Base Tumors— Single Brazilian Center Retrospective Study of 72 Cases

Introduction/Objectives: In 1986, Roberts et al developed the first frameless stereotaxic system based on computed tomography (CT) and magnetic resonance imaging (MRI). Since then, the systems have been upgraded allowing integration with angiography; tractography; endoscopy; PET scan;, and, more recently, intraoperative CT and MRI. Our objectives are to report the experience of a single Brazilian center using the frameless neuronavigation as a tool in the surgical treatment of skull base tumors, discussing the advantages and disadvantages of the method.

Materials and Methods: Retrospective study of 53 patients undergoing 72 surgeries from January 2008 to December 2011, using a frameless neuronavigation system (VectorVision2, BrainLab). We analyzed several parameters, including patients’ demographic characteristics, lesions characteristics, surgical approaches, surgical results, time needed to assemble and calibrate the neuronavigation system, and the navigation efficacy.

Results: Among 53 patients, 56.7% were female and the mean age was 49 years. The endoscopic endonasal approach was the most common surgical route (51.3%) followed by retrosigmoid (16.2%), pterional (15.2%), subtemporal (5.5%), frontolateral (4,1%), fronto-orbital (2.6%), far lateral (2.7%), and subfrontal (1.3%). Complete (gross total resection and Simpson I grade for meningiomas) resection was obtained in 58% of the cases. In the series, 19 patients needed re-operations, and in 52.6% of these, complete resection was achieved and only one patient had major complication (vascular injury). The main histopathological diagnoses were pituitary adenoma (45.8%), meningioma (25%), and vestibular schwannoma (13.8%). The mean time needed for planning was 32 minutes and for setting up the system in operative room was 4 minutes. Good accuracy was achieved at first calibration attempt in most cases.

Conclusion: Neuronavigation is an essential tool for increasing safety in skull base tumor resections, allowing identification of neurovascular structures previous to their surgical exposure. Overall, it does not increase the complete resection rate; once in this particular region, most incomplete resections are related to preservation of neural tissue and technical difficulties implied by the lesion itself. It does not significantly increase the surgical time and has become a less expensive technique through time being available in most neurosurgery services.