American Board of Internal Medicine (ABIM) Certification Practice Exam

Which aneurysm size indicates the possible need for surgical intervention in the posterior circulation?

1. 5 mm

2. 6 mm

3. 7 mm

4. 8 mm

The correct answer is: 7 mm

In the context of aneurysms in the posterior circulation, a size of 7 mm is often considered a threshold for potential surgical intervention. Aneurysms located in the posterior circulation, such as those on the vertebral arteries or basilar artery, are associated with a higher risk of rupture when they reach this size. The risk of rupture increases with the size of the aneurysm, and guidelines typically suggest that aneurysms larger than 7 mm should be considered for surgical evaluation due to the heightened risk they pose. This is particularly crucial in the posterior circulation, where the likelihood of complications from ruptured aneurysms, such as subarachnoid hemorrhage and subsequent neurological deficits, is significant. Smaller aneurysms, like those measuring 5 mm or 6 mm, are often monitored rather than surgically addressed unless there are additional risk factors present, such as patient age, family history of aneurysms, or symptomatic presentation. Aneurysms measuring 8 mm or larger may also prompt earlier intervention but, in this case, 7 mm serves as a critical threshold for taking action.