ABSTRACT
Aneurysmal subarachnoid hemorrhage (SAH) has a 30-day mortality rate reported to approach 50%1-4, and an additional 20% of patients are left dependent following SAH2. SAH accounts for nearly half of all mortality due to cerebrovascular disease in persons less than 35 years old5. The potential impact for the general population of cerebral aneurysm is difficult to measure because only limited data exist regarding the incidence of and prevalence of intracranial aneurysm (IA). Autopsy studies have suggested a mean prevalence of IA in the general population of 5%6. In Olmsted County, Minnesota, from 1965 to 1995, the incidence and prevalence of IA were 9.0/100 000 person-years and 83.4/100 000 person-years, respectively7. Whether IA should be sought in asymptomatic individuals and treated if identified are hotly debated issues. To resolve the issue, the natural history of an unruptured IA, risk of harboring an IA, risk of the treatment and the longterm cost-effectiveness of screening need to be determined.
