Secondary Outcome Measures include 1) Frequency of placements required, 2) Frequency of completed placements within the ventricle of the perforated part of the tip of the catheter, 3) Frequency of very early and early shunt failures (revision of the ventricular drainage within 24 hours / within three weeks, 4) Frequency and Percentage of complications (procedure-related and nonsurgical) within three weeks, 5) Length of the trajectories from the dura level to the foramen of Monroe, the angle in the coronal plane towards midline (a) and towards the target (b) at the respective entry point, 6) ventricle size (the frontal occipital horn ratio (FOHR) and the width of the lateral ventricle in the coronal plane between the medial wall of the corpus callosum and the septum), 7) Differences (angles, distance of catheter tip from target) on the tablet-guided planned and postoperative trajectory on control computer tomography within 48 hrs (CT).