Unruptured Intracranial Aneurysms Incidence of Rupture and Risk Factors

Backgrounds and Purpose - The authors evaluated the incidence of rupture of unruptured intracranial saccular aneurysm during observation. Methods - Between January 2003 and December 2006, a total of 419 patients with 529 unruptured intracranial saccular aneurysms were observed without treatment. The mean follow-up duration was 905.3 days. Aneurysm size was measured by 3-dimensional CT angiography. Clinical and 3-dimensional CT angiography follow-up were obtained every 6 months. Results - Nineteen aneurysms ruptured during observation resulting in a 1.4% rupture rate per year. A history of subarachnoid hemorrhage (hazard ratio, 7.3; 95% CI, 2.5 to 21.2), posterior circulation aneurysm (hazard ratio, 2.9; 95% CI, 1.1 to 8), and large size were significant independent predictors for aneurysm rupture. Conclusions - Size, history of subarachnoid hemorrhage, and posterior circulation aneurysms were significant risk factors for prediction of rupture of unruptured intracranial saccular aneurysms. (Stroke. 2009; 40: 313-316.)