Lost credit card cytotec misoprostol 200 mcg pfizer youtube A stroke—a decrease in blood flow to the brain due to a clot or bleeding—is a medical emergency. And doctors often say "time is brain," meaning the quicker you get treatment, the less likely it is that your brain tissue will be permanently damaged. About 80 percent of strokes are due to a clot (ischemic strokes) and the rest are due to bleeding in the brain (hemorrhagic stroke).