 MRI: There are small areas of acute infarction involving the right insular cortex, and right parietal cortex. There is subarachnoid hemorrhage in the right sylvian fissure, and scattered along the right temporal and occipital lobe sulci as well hemorrhage in the right occipital horn, not as well appreciated on CT. There is moderate diffuse volume loss and scattered T2 signal abnormalities in the periventricular and subcortical white matter most consistent with chronic microvascular ischemic changes. There is a small old right cerebellar hemispheric infarct. There are old pontine infarcts as well with significant encephalomalacia.MRA: There is a short segment of focal severe luminal irregularity and narrowing in the cavernous right internal carotid artery which is favored to represent atherosclerotic disease, much less likely aneurysmal dilatation (series 301 image 61). Only one major branch of the right MCA bifurcation is seen with the other expected large branch or branches presumed to be occluded. A paucity of right MCA vessels is seen more distally. There is luminal irregularity of the right M1 branch without high-grade stenosis. The anterior cerebral arteries are patent. There is no flow related enhancement at the expected location of the distal vertebral arteries. There is a prominent right posterior communicating artery and perhaps a hypoplastic left posterior communicating artery. There is flow related enhancement in both posterior cerebral arteries, right greater than left which may be in part due to decreased caliber of the left posterior cerebral artery as compared to the right. There is probable retrograde filling of the basilar artery tip. The basilar artery is markedly attenuated more proximally.
1.Small areas of acute infarction involving the right insular cortex and right parietal cortex. Occlusion of one or more of the branches off the right MCA bifurcation is suspected with paucity of distal right MCA branch vessels as compared to the left. Given the mismatch between the large vessel occlusion and few small infarcts, question is raised as to the chronicity of the vessel occlusion.2.Subarachnoid hemorrhage in the right sylvian fissure, right temporal and occipital sulci as well as intraventricular hemorrhage layering in the right occipital horn.3.Short segment high-grade focal stenosis of the distal right cavernous carotid artery with aneurysmal dilatation much less likely.4.Chronic microvascular ischemic changes and old cerebellar and pontine infarcts.5.Occlusion of bilateral vertebral arteries, proximal to mid basilar artery with retrograde filling of the basilar tip predominantly via a patent and large right posterior communicating artery. Again chronicity of these findings is uncertain particularly given the history of a chronic pontine infarct.