In ten patients authors used the Stereoplan Plus programme with a PC work station and Zamora- no-Dujovny stereotactic device for virtual planning of ventriculostomy in obstructive hydrocepha- lus. The accuracy of this system was plus minus 1 mm for navigation of the endoscope into the IIIrd ventricle for intervention. Duration of intervention was 20 minutes. The ventriculostomy was effected by a balloon-expandible stent.

        Key words: navigation - virtual reality - stereotaxy - minimal invasivity - cerebral endoscopy - ventriculostomy - stent