American Board of Internal Medicine (ABIM) Certification Practice Exam

For surgical consideration, what size of an unruptured intracranial aneurysm in the posterior circulation warrants treatment?

1. 3 mm or greater

2. 5 mm or greater

3. 7 mm or greater

4. 10 mm or greater

The correct answer is: 7 mm or greater

The indication for surgical intervention in unruptured intracranial aneurysms, particularly in the posterior circulation, is primarily guided by the size of the aneurysm due to the associated risk factors for hemorrhage. In the case of posterior circulation aneurysms, a threshold of 7 mm is generally recognized as significant for recommending surgical treatment. Aneurysms that are 7 mm or greater carry a higher risk of rupture compared to smaller aneurysms. The posterior circulation specifically is associated with a higher complication rate when ruptured, which underscores the need to be more aggressive in their management. Surgical intervention, whether endovascular or open surgical clipping, aims to prevent potential rupture and the resultant morbidity or mortality that can accompany such events. In contrast, smaller aneurysms, such as those measuring less than 7 mm, tend to have a lower risk profile for rupture, thus making a conservative approach more appropriate unless other risk factors are present, such as patient symptoms or certain anatomical considerations. This is why the 7 mm threshold is pivotal in clinical decision-making regarding the treatment of posterior circulation aneurysms.