The two categories of stroke are ischemic and hemorrhagic. The more common, ischemic, is caused by a blockage of an artery or other blood vessel. Ischemic strokes kill brain cells downstream from the blockage by cutting off the blood's supply of oxygen and glucose that brain cells need to survive. There are three kinds of ischemic strokes. A thrombotic stroke blocks blood flow in an artery feeding the brain when a clot forms on pre-existing deposits on the artery walls.
Many thrombotic strokes occur in large blood vessels.
A second type of ischemic stroke, small vessel thrombotic stroke, is called lacunar because a small cavity opens within the brain after this kind of stroke. Ischemia causes 83 percent of strokes. Fifty-one percent of these are thrombotic, and 31.5 percent are embolic. The second category of stroke is hemorrhagic, a breaking, tearing or bursting in the wall of a blood vessel. Blood not only fails to deliver its nutrients, but it also causes direct physical damage.