The natural history of radiographically defined vertebrobasilar nonsaccular intracranial aneurysms.

Background: Vertebrobasilar nonsaccular intracranial aneurysms (VBNIA) are characterized by dilatation, elongation, and tortuosity of the vertebrobasilar system.

Methods: The medical records and imaging of patients with vertebrobasilar fusiform aneurysms or dolichoectasia between 1989 and 2001 were reviewed. Prospective follow-up was obtained.

Results: One hundred and fifty-nine patients were identified (74% male) with 719 patient years of follow-up. Presenting events included: hemorrhage (3%), ischemia (28%), and compression (22%). The remainder were incidental. The 1-, 5-, and 10-year risk of cerebral infarction (CI) due toVBNIA is 2.7, 11.3, and 15.9% respectively. The risk of recurrent CI is 6.7% per patient year. Median survival was 7.8 years and death was most commonly due to ischemia.

Conclusions: VBNIA are more common in men and typically present in the 6-7th decade. Recurrent CI is more common than hemorrhage risk.