Incidence and Outcome of Multiple Intracranial Aneurysms in a Defined Population

Background and Purpose— Proportions of patients with single and multiple aneurysms among patients suffering from subarachnoid hemorrhage (SAH) are not well established. We evaluated these proportions and the differences in outcome between SAH patients with a single aneurysm and those with multiple aneurysms in a defined population. Methods— Between 1989 and 1998, 2037 patients (age, 20 to 89 years) with ruptured intracranial aneurysm were treated in 11 hospitals in Nagasaki Prefecture. Multiple aneurysms were found in 361 of these patients. Age- and sex-specific incidences of ruptured aneurysm per 100 000 people were calculated. Results— For both single and multiple aneurysms, the incidences were significantly higher in women than in men 60 to 69 and 70 to 79 years of age. In every age category except 80 to 89 years, the frequency of multiple aneurysms was higher in women than in men. The overall frequency of multiple aneurysms was 20.2% in women, which was significantly higher than the 12.4% in men (P<0....