In this paper, we described a patient with a basilar tip aneurysm complicated by bilateral carotid occlusions and a patient with the formation of the vertebrobasilar dolichoectasia following bilateral carotid occlusions.
The patient with a basilar tip aneurysm had had no ischemic symptoms following bilateral carotid occlusions because the vertebrobasilar artery supplied enough blood flow for both cerebral hemispheres through both posterior communicating arteries. We performed a craniotomy and coated the aneurysm.
In the second patient, the bilateral carotid occlusion had caused moderate ischemic symptoms of the left cerebral hemisphere. The vertebrobasilar artery completely perfused the right cerebral hemisphere through the right posterior communicating artery. Six years after the left STA-MCA bypass surgery, we found the devolopment of the dolichoectasia in the vertebrobasilar artery. A right STA-MCA bypass was performed to reduce the hemodynamic stress to the dolichoectasia. Digital subtraction angiography revealed the reduction of the dolichoectasia and good patencies of both STA-MCA bypasses 10 months after right STA-MCA bypass surgery.
The mechanism and therapeutic problems of aneurysmal formation in the posterior circulation following bilateral carotid occlusion are discussed.