Indications for Endovascular Treatment of Unruptured Cerebral Aneurysms

We investigated the indications for endovascular treatment of unruptured cerebral aneurysms based on the natural history reported in ISUIA and our treatment results. At Nagoya University hospital and affiliated hospitals over 7 years we treated or attempted embolization for 383 unruptured aneurysms, including 301 asymptomatic and 82 symptomatic ones. Among them, 326 were treated with embolization and 57 were left untreated due to the high risks involved. Ruptures during the follow-up occurred in 2 symptomatic cases without treatment. We experienced 28 technical complications including 9 hemorrhagic, 14 ischemic and 4 others at the intra- and perioperative stage, in addition to 14 recanalizations at the delayed stage. The rate of morbidity associated with procedure was 4.0%. There was a high risk of hemorrhagic complications from a tiny anterior communicating artery aneurysm and ischemic complications in the middle cerebral, basilar-tip, and vertebral dissecting aneurysms with a hypoplastic posterior inferior cerebellar artery. As for the symptomatic aneurysms, although 72 patients had a good outcome, symptoms due to mass effects did not improve in 19 cases and worsened in 7. Particularly large paraclinoid aneurysms with visual symptoms showed a reduced possibility of symptom improvement. Although embolization has proved highly effective for the treatment of unruptured aneurysms, the treatment decision should take into account the relevant guidelines, including those for surgical option and observation. Abbreviations: ISUIA: International Study of Unruptured Intracranial Aneurysms