18-year-old with history of stroke status post pial synangiosis at outside hospital. MRI: There is extensive encephalomalacia throughout the vast majority of the right side cerebral hemisphere with relative sparing of the inferior frontal and anterior mesial temporal lobes. There is associated right brainstem Wallerian degeneration, ex vacuo dilatation of the right lateral ventricle, right Dyke-Davidoff-Masson, as well as approximately 7 mm of rightward midline shift. There is mild periventricular T2 hyperintensity in the left cerebral hemisphere. There is no evidence of acute intracranial hemorrhage, mass, or acute infarct. The orbits are unremarkable. MRA: There is a patent anastomosis between the bilateral superficial temporal arteries and distal branches of the middle cerebral arteries. Otherwise, there is extensive steno-occlusive diease of the anterior circulation, right more than left. There is also proliferation of lenticulostriate collateral vessels within the basal ganglia. Right dominant vertebrobasilar. There is a right posterior communicating artery that communicates with collateral vessels. The right posterior cerebral artery is diminutive, while the left right posterior cerebral artery, basilar artery, and vertebral arteries are intact.
1. Extensive chronic infarction of the right cerebral hemisphere, but no evidence of acute infarction.2. Patent bilateral pial synangiosis, but extensive steno-occlusive disease involving the anterior circulation with moyamoya, right more severe than left.