Experimental Medicine Brain Focal Impairment and Hemodynamic Parameters in Relation to the Type of Collateral Supply

ABSTRACT. The aim of the paper was to study the relationship between collateral flow via different pathways and cerebral hemodynamic parameters in patients with unilateral high-grade internal carotid artery (ICA) changes. Materials and Methods: 41 patients with severe stenosis and 30 patients with occlusion of ICA underwent brain MRT, 3D TOF-MR-angiography, Color Doppler of extra-intracranial vessels to investigate collateral flow via the circle of Willis and via the ophthalmic artery (OphA). Maps of the cerebral perfusion parameters were calculated. Results: In 50(70%) cases “symptomatic ” cerebral ischemia was noted. In symptomatic patients cortical MCA infarctions (13(26%)), and border-zone infarctions-10(20%) prevailed. In cases of unilateral ICA occlusion com-pensatory dilatation of contralateral ICA and enhancement of flow volume by 60%, additionally enhancement of flow in the vertebral arteries by 18 % was observed. Patients without collateral flow via the circle of Willis or flow via the PComA only have higher incidence of brain infarction (13(85%)) and impaired hemodynamic parameters in the MCA(V mean-38cm/s, PI-0.69) than patients with collateral flow via the AComA (2 infarctions, Vmean-44cm/s, PI-0.77). Patients with reversed OphA could prove an additional risk for infarction. Patients with collateral flow via both AComA and PComA had less increased rCBV than those without. Conclusion: Patients with collateral flow via the PComA and reversed OphA flow have more impaired hemody-namic parameters and a higher risk of brain infarctions than patients with collateral flow via the AComA. Comple