Why is immediate treatment so important for a stroke?

Immediate treatment for stroke is extremely important because nervous system tissue requires a constant supply of oxygen. As soon as the oxygen supply is cut off, and the oxygen typically is delivered by the blood. So when the blood flow is cut off the oxygen supply is cut off. And tissue injury begins at that point. If that remains untreated and the blood flow remains blocked then over a period of minutes to hours, permanent damage accumulates. So that there is a very short window of time after which a blood vessel becomes blocked where you could go in, unblock the vessel restore flow, and decrease the amount of permanent damage that's done from that particular episode.  Generally the time windows that we look at for clinical treatment of stroke are a time window of somewhere between three and six hours. There are several methods that we can use to unblock arteries. And depending on what method we are considering using the time window may vary a bit. But in general, treatment needs to start within about 3 to 6 hours. And it's important to remember that includes traveling to a hospital, being seen and evaluated, and receiving diagnostic tests. So that process itself typically takes up a fair amount of time. So it's vital that, as soon as symptoms are recognized, a person goes to a hospital to get evaluated and treated.