CEREBRAL HEMISPHERIC LOW-FLOW INFARCTS IN ARTERIAL OCCLUSIVE DISEASE - LESION PATTERNS AND ANGIOMORPHOLOGICAL CONDITIONS

Background and Purpose Among the pathogenetic causes of subcortical he mispheric infarcts are small-vessel disease, thromboembolic occlusions of small arteries, and hemodynamic compromise in low-flow conditions. A topographic classification of these infarcts based on CT and MRI ca n be misleading. Methods We evaluated 30 consecutive patients with pre sumed supratentorial low-flow infarcts. CT was available in all cases, with additional MRI in 14 patients. In all cases the occlusion patter n of the extracranial and intracranial arterial system was studied in detail with angiography. Results The dominant lesion patterns seen on CT and MRI were multilocal chainlike lesions in 19 and confluent stria ted lesions in 8 cases located in the supraventricular and paraventric ular deep white matter. In 8 patients subcortical lesions extended int o the adjacent cortex. Angiography revealed that extracranial occlusiv e disease (n=24) or stenosis of the middle cerebral artery (n=6) was a lways accompanied by impairment of the circle of Willis, in either the anterior part (n=5) and/or the posterior part (n=16). Moreover, lepto meningeal pathways indicative of vascular hemispheric compromise were identified in 26 cases. In total, 29 of 30 patients displayed a noncom petent circle of Willis. Conclusions Low-flow infarcts show typical bu t not pathognomonic lesion patterns on CT and MRI. Definite diagnosis requires knowledge of the complex vascular compromise of the extracran ial and/or intracranial arterial system. A noncompetent circle of Will is should be regarded as the additional predisposing condition in hemi spheric low-flow infarcts.