The pathogenesis of vertebrobasilar ischemia is not different from the
one in the carotid territory. Arterio-arterial embolism from arterios
clerotic vascular lesions, local thrombosis and cardiogenic embolism a
re major causes. The long-term prognosis for proximal vertebral artery
(VA) stenosis is dependent on associated carotid artery disease. Dist
al VA and basilar artery (BA) disease has a variable prognosis, which
is determined by the extent of collateralization. The risk of repeated
local ischemic events seems to be less than in the anterior circulati
on. For survivors of BA occlusion, with or without local fibrinolytic
therapy, the long-term prognosis is favorable.