Age , dissecting aneurysm type , ruptured vertebrobasilar aneurysm , Fisher grade , Hunt and Hess grade , admission intraventricular hemorrhage , admission intraparenchymal hemorrhage , blood in the fourth ventricle on admission , perioperative ventriculostomy , and hemicraniectomy were significant risk factors ( P < @ ) associated with shunt-dependent hydrocephalus on univariate analysis .