Why is it important to emphasize the concept of time to treat acute stroke patients and to raise the awareness of the whole population? Recent statistics in Beijing show that the number of deaths from acute stroke is 4-5 times higher than that of acute heart attack! This indicates that the incidence of stroke is increasing year by year, and on the other hand, it suggests that the awareness of acute stroke is not yet strong enough for all people to seek urgent medical attention, and the best time for treatment is missed. In recent years, the slogan “time is brain” has been raised worldwide. The aim is to raise the awareness of time, reduce the death rate of stroke and improve the quality of life. This is due to the pathophysiological characteristics of stroke; once the blood supply to the brain is interrupted, nerve cell metabolism is affected within 6 seconds, loss of consciousness within 10-15 seconds, and cessation of electrical activity within 2 minutes, and irreversible cellular damage occurs if it lasts for more than 5 minutes. In the pathological staging of ischemic stroke: ① ultra-early stage (1-6 hours); brain tissue in the lesion area is often not significantly changed, some vascular endothelial cells, nerve cells and astrocytes are seen to be swollen, and mitochondria are swollen and cavitated; (the best time for thrombolysis) ② acute stage (6-24 hours); brain tissue in the ischemic area is pale, mildly swollen, and nerve cells, astrocytes and endothelial cells of blood hanging tubes are significantly ischemic changes. ③ Necrotic phase (24-48 hours); a large number of neuronal cells are seen to disappear, glial cells are necrotic, inflammatory cells are infiltrated, and brain tissue is obviously swollen; ④ Softening phase (3 days-3 weeks); the lesion area is liquefied and softened; ⑤ Recovery phase (after 3-4 weeks) liquefied necrotic brain tissue is phagocytosed and cleared, glial cells are proliferated, capillaries are proliferated, small lesions form glial scars, and large lesions form stroke sacs, and this phase can last from several months to 2 years. There are half of the dark zone problems in the early stages of the disease; this is the key to treating stroke. Because irreversible damage has occurred to the neuronal cells in the central area of the infarct, there is a peripheral ischemic border zone where blood flow is between the thresholds of electrical failure and membrane failure (cells survive with reduced function but maintain ionic homeostasis), and this area becomes the semidark zone. This zone receives a partial blood supply due to the presence of collateral circulation, and the damage remains reversible if blood flow is rapidly restored. Protection of these neurons is crucial for successful treatment of acute cerebral infarction. There is also a reperfusion time window and the question of reperfusion injury: within how long is it possible to restore blood perfusion to the ischemic brain tissue and save the ischemic nerve cells? This time is called the reperfusion time window. It is now commonly set at 6 hours or less. If cerebral blood flow is recanalized beyond the time frame of the reperfusion time window, brain injury can continue to increase, a phenomenon called reperfusion injury. This is due to ischemia of the vessel wall at the distal end of the occlusion, increased permeability of the vessel wall, and opening of the blood-cerebrospinal fluid barrier, which can lead to leakage of blood components from the ischemic vessel wall and aggravate cerebral edema or cause hemorrhagic infarction. Accordingly, most hospitals in China set the “time window for thrombolysis” at 3-6 hours. It is clear that acute stroke should be treated in a time-sensitive manner.