There are three major types of stroke: Embolic, Thrombotic, and Hemorrhagic.
In an embolic stroke, a small artery of the brain is blocked by either a blood clot, usually from the heart, or a broken piece of arterial plaque, which has travelled up through the blood stream.
In a thrombotic stroke, a large, localized arterial plaque (which is the result of the build up of fatty deposits and cholesterol) impedes blood flow by blocking an artery. As a result, the brain region receiving blood from this artery no longer gets sufficient oxygen and the affected cells die. This form of stroke is referred to as thrombotic stroke because the blocking clot is a thrombus.
A hemorrhagic stroke results from a breakage of blood vessels in the brain. A cerebral hemorrhage can be caused by a number of conditions affecting the blood vessels. However, the two most common causes of hemorrhage are high blood pressure and ruptured cerebral aneurysms. In an aneurysm, a weak spot on a blood vessel wall dilates, thus forming a balloon. Aneurysms are usually present at birth, and develop over a number of years. They do not cause detectable behavioural or motor problems until they become enlarged or rupture.