Natural Course of Dissecting Vertebrobasilar Artery Aneurysms without Stroke

BACKGROUND AND PURPOSE: The natural history and therapeutic management of dissecting vertebrobasilar aneurysms without ischemic or hemorrhagic stroke (nonstroke dissecting vertebrobasilar aneurysms) are not well-established. We conservatively followed patients with nonstroke dissecting vertebrobasilar aneurysms and evaluated the factors related to clinical and morphologic deterioration. MATERIALS AND METHODS: One hundred thirteen patients were enrolled and divided by clinical presentation at diagnosis: asymptomatic (group 1, n = 52), pain only (group 2, n = 56), and mass effect (group 3, n = 5). Patients were conservatively managed without intervention and antithrombotic therapy. Clinical outcomes and morphologic changes were analyzed. RESULTS: A total of 113 patients who were diagnosed with nonstroke dissecting vertebrobasilar aneurysm had a mean follow-up of 2.9 years (range, 27 days to 8 years). Throughout that period, 1 patient in group 1 (1.9%) and 1 patient in group 2 (1.8%) showed clinical deterioration due to mass effect, and 1 patient in group 3 (20%) developed ischemic stroke followed by subarachnoid hemorrhage. Most patients (97.3%) were clinically unchanged. Three patients who had clinical deterioration showed aneurysm enlargement (P < .001). Aneurysms remained morphologically unchanged in 91 patients (80.5%). Aneurysm enlargement was seen in 5 patients (4.4%); risk of enlargement was significantly associated with either maximum diameter (hazard ratio = 1.30; 95% CI, 1.11-11.52; P = .001) or aneurysm >= 10 mm (hazard ratio = 18.0; 95% CI, 1.95-167; P = .011). CONCLUSIONS: The natural course of these lesions suggests that acute intervention is not always required and close follow-up without antithrombotic therapy is reasonable. Patients with symptoms due to mass effect or aneurysms of >10 mm may require treatment.