The exam helps to identify individuals who are at risk for low-flow ischemia (ischemia risk). The impairment of Cerebral Autoregulation (VMR) had a high potential to predict poor prognosis in patients with carotid stenosis or intracranial stenosis. The cerebral vasomotor reactivity (VMR) represents the capability of arterioles to dilate and constrict in order to maintain cerebral blood flow.