Do you know the signs and symptoms of a stroke or what do you if you or someone you love may be experiencing a stroke? Franciscan Health explains the proper response in this situation. A stroke occurs when blood flow to a part of the brain is cut off or drastically reduced. Brain cells begin to die when they are deprived of oxygen and glucose. Permanent brain damage or death is possible if a stroke is not caught early. It is important to know what to do and be able to respond quickly.