The management of cerebral aneurysms is still the subject of controversy in spite of recent dramatic advances in surgical techniques and neuro-intensive care. Currently, two main topics in this field have totally different aspects: 1. the management of unruptured cerebral aneurysms as a preventive medicine and 2. neurocrutical management of severe subarachnoid hemorrhage (SAH) after the rupture. These topics were discussed during the Swiss-Japanese Joint Conference in Zurich, Switzerland, in May 2001. Selected papers from this meeting are included in this volume presenting new clinical experiences in order to find out updated and proper ways to focus the treatment and providing updated information on neurocritical care aspects as well as endovascular and surgical treatment modalities carried out in daily practice in Zurich and Japan.