Endoscopic biopsy of foramen of Monro and third ventricle lesions guided by frameless neuronavigation: usefulness and limitations.

OBJECTIVES: To describe our institution experience regarding the usefulness and limitations of frameless neuronavigation in the endoscopic biopsy of foramen of Monro and third ventricle lesions.
METHODS: We report our experience with 22 patients harbouring intraventricular lesions located in the region of the foramen of Monro or the third ventricle who underwent endoscopic biopsy guided by the neuronavigation system. Nine lesions were located on the posterior aspect of the third ventricle or at the pineal region, and thirteen lesions were located at the foramen of Monro or anterior third ventricle region. The endoscopes were introduced via an operating sheath, which had previously been inserted with a trocar under neuronavigational control. After approaching the foramen of Monro from the planned angle, surgery was continued under direct visualisation until the lesion was reached, if it was located on the third ventricle. In cases where the lesion was located at the foramen of Monro, an excellent view of the lesion was obtained and neuronavigation was used to determine the location of critical areas.
RESULTS: Histological examination of biopsy specimens obtained endoscopically was diagnostic in all cases. Open surgery following endoscopic biopsy was only needed in 1 patient out of 22.
CONCLUSION: In our experience, image-guided neuroendoscopy can improve the accuracy of the endoscopic approach, minimising brain trauma. It can be particularly helpful when performing a brain biopsy in the absence of clear intraventricular landmarks or in the event of adverse visual conditions such as intraventricular bleeding.