160 patients with ischemic stroke who underwent multislice computed tomography (MSCT) angiography or magnetic resonance angiography (MRA) were examined. Depending on the state of the circle of Willis (CW) , patients were divided into two groups: the first group consisted of 105 (65.6%) patients with open CWand the second group, which included 55 (34.4%) patients with closed CW. Patients with open CWwere divided into two subgroups: group I -a - acquired defects in CW- 79 (75.2%) patients, and group II b - congenital anomalies of CW- 26 (24.8%) patients. In a comprehensive clinical and neuroimaging examination of 160 patients who underwent stroke, anomalies of the CWwere found in 105: anterior trifurcation in 34.6%, posterior trifurcation in 46.2% , dissociation of the CWassociated with the absence of ACoA in 15.2%, PCoAin 52,2%. Anomalies of the CWwere combined with other congenital and acquireddefects: hypoplasia of the vertebral arteries, stenosis or occlusion of the internal carotid artery. Visual assessment of collateral blood flow using MSCT angiography in patients with stroke in the presence of an open CWrevealed a depletion of blood flow in the cerebral hemispheres compared with patients with closed CW. Thus, the inferiority of the CWcontributes to a decrease in collateral blood flow and disruption of the processes of compensation of cerebral hemodynamics in this category of patients.

atherosclerosis, stroke, anomaly, circle of Willis, risk factor.