What is a stroke?
A stroke, or cerebrovascular accident (CVA), occurs when blood supply to part of the brain is disrupted, causing brain cells to die. When blood flow to the brain is impaired, oxygen and glucose cannot be delivered to the brain. Blood flow can be compromised by a variety of mechanisms. Blockage of an artery • Narrowing of the small arteries within the brain can cause a so-called lacunar stroke, (lacune=empty space). Blockage of a single arteriole can affect a tiny area of brain causing that tissue to die (infarct). • Hardening of the arteries (atherosclerosis) leading to the brain. There are four major blood vessels that supply the brain with blood. The anterior circulation of the brain that controls most motor, activity, sensation, thought, speech, and emotion is supplied by the carotid arteries. The posterior circulation, which supplies the brainstem and the cerebellum, controlling the automatic parts of brain function and coordination, is supplied by the vertebrobasilar arteries. If
A stroke is a condition that causes death of brain tissue. Brain tissue death is usually caused by interruption of blood flow to that tissue. This can be caused by a blood clot in a vessel blocking the blood supply to an area of the brain, or by the rupture of a blood vessel causing bleeding in the brain. Strokes result from vascular disease. Narrowed arteries with cholesterol plaque are easily blocked by a small blood clot. Narrowed cholesterol filled arteries can actually cause clot formation if the cholesterol is brittle and develops small cracks in it’s surface. A weakening of an arterial wall can lead to the formation of a small aneurysm, or bulging area that may burst causing bleeding and loss of blood flow to areas of the brain supplied by that artery. High blood pressure plays a large roll. High blood pressure, over time, damages arterial walls leading to areas that allow cholesterol plaque to adhere and build up. Fluctuations in blood pressure can then crack cholesterol plaque
