0 no perfusion
1 antegrade perfusion past the initial occlusion, but limited distal branch filling with little or slow distal reperfusion
2a antegrade perfusion of < 50% of the ischemic territory of the occluded target artery (e.g. in 1 major division of the MCA & its territory)
2b antegrade perfusion of > 50% of the ischemic territory of the occluded target artery (e.g. in 2 major divisions of the MCA & their territories)
3 complete antegrade reperfusion of the ischemic territory of the occluded target artery, with absence of visualized occlusion in all distal branches