Computed tomography of vertebrobasilar artery aneurysm.

Review of computed tomographic as well as clinical and angiographic findings in 19 patients with vertebrobasilar artery aneurysms has revealed that there are two roentgenographically and clinically distinct types of aneurysms: saccular and fusiform. The saccular aneurysms often present with acute subarachnoid hemorrhage that differs in distribution from that seen with anterior circulation aneurysms. Small interpeduncular cisternal hematomas are helpful in localization of these aneurysms. Fusiform aneurysms of the basilar artery frequently present as posterior fossa mass lesions and have a fairly characteristic appearance on computed tomograms.