Impact of carotid disease on posterior circulation in patients with vertebral artery occlusion ― a functional transcranial Doppler study

Almost one quarter of all ischemic strokes occur in posterior circulation. Approximately 20% of posterior circulation strokes evolve as a result of vertebral artery (VA) disease (1, 2). The most common causes of vertebral artery occlusion are development of atherosclerotic plaque and embolism, but dissection should also be taken into account, mostly occurring after neck trauma (3). Carotid disease represents an important risk factor for ipsilateral ischemic stroke and TIA in anterior circulation (4, 5, 6). Also, it can be correlated with the occurrence of disturbances in posterior circulation, since in some patients the collateral pathways redirect the posterior blood flow to anterior circulation (7). A study by Delcker and al. showed that a significantly higher rate of TIA in the vertebrobasilar system occurred in patients with combined carotid and vertebral artery disease (8).