Unruptured Cerebral Aneurysms: Evaluation and Management
Table 3
Summary of large studies evaluating the microsurgical clipping of unruptured cerebral aneurysms.
Study
Important findings
International Study of Unruptured Intracranial Aneurysms (ISUIA) [12, 15]
Overall, morbidity and mortality were the highest in patients older than age 50 years and with aneurysms that were large or in the posterior circulation. In a cohort of 1917 prospectively evaluated patients, combined morbidity and mortality at 1 year was 12.6% for those without prior hemorrhage (death was 2.7%; functional disability was 1.4%; impaired cognitive status was 5.5%) and 10.1% for those with previous subarachnoid hemorrhage from some other aneurysm (death was 0.6%; functional disability was 0.9%; impaired cognitive status was 7.1%)
Surgical clipping in 4619 patients was associated with higher survival estimates (hazard rate of death 30%) and low neurologically related causes of death (2.3%)
Ogilvy and colleagues at Massachusetts General Hospital [17]
Treatment of 604 unruptured aneurysms showed an overall morbidity and mortality of 15.9% and 0.8%, respectively. Treatment risk for large aneurysms was 5% in the anterior versus 15% in the posterior circulation in the elderly, while treatment risk was 2% in young patients with aneurysmal size <10 mm
Moroi and colleagues at the Research Institute for Brain and Blood Vessels [18]
Treatment of 549 unruptured aneurysms showed a mortality and morbidity of 0.0% and 0.6% for aneurysms <10 mm and a mortality and morbidity of 1.2% and 6.1% for aneurysms >10 mm
Meta-analysis using Cochrane Database by Kotowski et al. [19]
Analysis of 60 studies (from 1990 to 2011) with 9845 patients with 10,845 aneurysms showing a mortality rate of 1.7% and an overall morbidity rate of 6.7%. Significant risk factors for poor surgical prognosis included aneurysm size >10 mm and posterior circulation aneurysms ( < 0.001)
