Ischemic stroke etiology: Ischemic stroke is a disorder of cerebral blood circulation caused by various causes, especially cerebral vascular stenosis or occlusion, followed by ischemic necrosis of brain tissue and consequent clinical symptoms. These causes include atherosclerotic stenosis, vascular occlusion, vascular entrapment, smog, atrial fibrillation, heart valve lesions, cardiac arrhythmias, systemic hematologic disorders, vasculitis, and other diseases. Not all cerebral infarcts are caused by stenosis or occlusion of arteries, but venous infarcts can also occur in the venous return of brain tissue, such as cortical vein thrombosis and intracranial venous sinus thrombosis.