A stroke is the sudden death of brain cells due to a problem with the blood supply. When blood flow to the brain is impaired, oxygen and important nutrients cannot be delivered. The result is abnormal brain function. Blood flow to the brain can be disrupted by either a blockage or rupture of an artery to the brain. There are many causes for a stroke, as shown in the table and discussed below. A stroke is also referred to as a cerebrovascular accident or CVA.