Frame-based and frameless endoscopic procedures in the third ventricle.

Stereotactic guidance is useful for planning an accurate trajectory to the third ventricle. A guiding block with a ball joint was developed for frame-based endoscopy and adaptors for arm-based and armless navigation systems. Between 1992 and 1996, 52 patients were operated on endoscopically in the third ventricle under stereotactic guidance. Thirty-eight ventriculostomies, 13 biopsies and 10 cystic lesions were performed. The coordinates of two points were calculated; one in the foramen of Monro and the second in the third ventricle. The ventriculostomy was performed under endoscopic control bluntly with a Fogarty catheter in front of the basilar artery. Twenty-seven (71%) of the patients had a long-lasting benefit from the operation, 6 (16%) had no benefit, and in 5 (13%) a shunt operation was necessary. Poor outcome was due to closure of the stoma by tumor growth or infection. Three cysts were fenestrated and 7 colloid cysts partly evacuated. One incident of bleeding occurred in the frontal lobe in the path of the endoscope which was treated conservatively with success. Transient memory deficit was noted in one patient and double vision in the second.