Abstract
This paper described the findings obtained in 4 cases of unilateral occlusion of the internal carotid artery, in which differences in diameter of the middle cerebral artery (MCA) were demonstrated by three-dimensional CT angiography (3D-CTA) between the occluded and non-occluded side. The main angiographic collateralization was Willisian in 2 cases, and ophthalmic in the other 2 cases. However, the collateral circulation was poor as seen on angiograms, and cerebral infarctions were detected at the borderzone area by CT scans in all of the 4 cases. The mean maximal diameter of the horizontal portion of the MCA on the occluded side was 2.5 mm, which was significantly smaller than that of the non-occluded side (3.9 mm; p<0.05) or of control subjects (3.4 mm). The mean cerebral blood flow in the MCA territories on the occluded side was about 16 ml/100 g/min as measured by xenon-CT, and the mean flow velocity in the horizontal portion of the MCA was 13 cm/sec as determined with a 2 MHz pulsed transcranial doppler velocimeter. These data suggest the presence of severely dysfunctioned cerebral hemodynamics. The clinical significance of the existence of laterality in the diameter of the MCA on 3 D-CTA is discussed in relation to the detection of abnormal cerebral hemodynamics.
