- Atherosclerotic extracranial proximal vertebral artery stenosis demonstrated by angiography(any of the following): 1) bilateral vertebral artery stenosis ≥70%, or vertebral artery stenosis ≥70% concomitant occlusion of contralateral vertebral artery; 2) superior lateral vertebral artery stenosis ≥70%; 3) non-superior lateral vertebral artery stenosis ≥50%, but the vertebral artery was directly extended to the posterior inferior cerebellar artery on this side and symptoms were related to insufficiency of the ipsilateral posterior inferior cerebellar artery.