Pathophysiology
Clinical meaning
Ischemic stroke (87% of strokes) results from arterial occlusion by thrombosis or embolism, causing focal cerebral ischemia. The ischemic core becomes irreversibly damaged within minutes, but the surrounding penumbra remains viable for hours if perfusion is restored. Thrombotic stroke typically occurs in large vessels with atherosclerotic plaque rupture. Cardioembolic stroke originates from the heart (atrial fibrillation, LV thrombus, valvular disease). Lacunar stroke results from lipohyalinosis of small perforating arteries. Hemorrhagic stroke (13%) involves intracerebral hemorrhage (ICH, usually from hypertensive arteriolar rupture) or subarachnoid hemorrhage (SAH, from ruptured aneurysm). Time is brain: approximately 1.9 million neurons die per minute during untreated ischemic stroke. IV alteplase (tPA) within 4.5 hours and mechanical thrombectomy within 24 hours (large vessel occlusion with salvageable tissue) are evidence-based reperfusion strategies.