COLLATERAL ABILITY OF THE CIRCLE OF WILLIS ASSESSED WITH TRANSCRANIAL DOPPLER IN PATIENTS WATERSHED INFARCTS

Objective To assess the collateral ability of the circle of Willis in patients with watershed infarcts.Methods In 100 patients with unilateral internal carotid artery occlusion,collateral circulation pathway in the circle of Willis was measured with transcranial Doppler.Results In patients with watershed infarcts(n=48),collateral circulation pathway in the circle of Willis was not found in 27%,and collateral flow in the posterior communicating artery was found in 13%.In patients without watershed infarcts(n=52),collateral circulation pathway in the circle of Willis not was found in 4%,and the percentage of collateral flow via the posterior communicating artery greatly increased to 52%(P0.01).The percentage of collateral flow via the anterior communicating artery was in the same range for patients with/without watershed infarcts(63% and 67%,respectively).Conclusions In patients with unilateral internal carotid artery occlusion,no collateral circulation pathway in the circle of Willis and a low percentage of collateral flow via the posterior communicating artery is associated with watershed infarcts.