Randomization The randomization will start as soon as possible after consent to the study has been obtained. Any patient meeting the inclusion criteria and not violating the exclusion criteria may participate in the TABGUIDE study and be randomized to either a guided or freehand ventriculostomy, thus defining the two distinct groups " guided " or " freehand ". Online randomization will be performed by the treating physician in the study center using permuted blocks, to ensure an equal number of patients in both study arms.