“…[5][6][7] Risk factors for hyperperfusion have been proposed, including high-grade stenosis, poor collateral circulation, high blood pressure, age, and bloodbrain barrier breakdown. [7][8][9][10][11] Nevertheless, the underlying pathophysiology of HPS has not been well evaluated due to its low incidence (0.7%-3%). 7,9,12 The generally accepted explanation emphasizes a failure of autoregulation after sudden augmentation of cerebral blood inflow following carotid stent placement.…”