Frameless navigation and endoscopy

Object. Frameless computerized neuronavigation has been increasingly used i n intracranial endoscopic neurosurgery. However, clear indications for the application of neuronavigation in neuroendoscopy have not yet been defined. The purpose of this study was to determine in which intracranial neuroendo scopic procedures frameless neuronavigation is necessary and really benefic ial compared with a free-hand endoscopic approach. Methods. A frameless infrared-based computerized neuronavigation system was used in 44 patients who underwent intracranial endoscopic procedures, incl uding 13 third ventriculostomies, nine aqueductoplasties, eight intraventri cular tumor biopsy procedures or resections, six cystocistemostornies in ar achnoid cysts, five colloid cyst removals, four septostomies in multilocula ted hydrocephalus, four cystoventriculostomies in intraparenchymal cysts, t wo aqueductal stent placements, and fenestration of one pineal cyst and one cavum veli interpositi. All interventions were successfully accomplished. In all procedures, the navigational system guided the surgeons precisely to the target. Navigational tracking was helpful in entering small ventricles , in approaching the posterior third ventricle when the foramen of Monro wa s narrow, and in selecting the best approach to colloid cysts. Neuronavigat ion was essential in some cystic lesions lacking clear landmarks, such as i ntraparenchymal cysts or multiloculated hydrocephalus. Neuronavigation was not necessary in standard third ventriculostomies, tumor biopsy procedures, and large sylvian arachnoid cysts, or for approaching the posterior third ventricle when the foramen of Monro was enlarged. Conclusions. Frameless neuronavigation has proven to be accurate, reliable. and extremely useful in selected intracranial neuroendoscopic procedures. Image-guided neuroendoscopy improved the accuracy of the endoscopic approac h and minimized brain trauma.