Types of Stroke
Approximately 80 percent of strokes, or brain attacks, are ischemic. They can develop in major blood vessels on the surface of the brain (called large-vessel infarcts) or in small blood vessels deep in the brain (called small-vessel infarcts).
Specific types of ischemic stroke include embolic infarct, thrombotic infarct, and lacunar infarct. Infarct of undetermined cause accounts for approximately 30 percent of cases of ischemic stroke.
Tissue death caused by lack of blood (embolic infarct) occurs suddenly when a blood clot (embolism) forms in one part of the body, travels through the bloodstream, and lodges in and obstructs a blood vessel in the brain. Cardiac embolism, in which a blood clot forms in the heart, accounts for about 2030 percent of ischemic strokes.
Thrombotic infarct (approx. 1015 percent of cases) occurs when a blood clot forms in an artery that supplies the brain, causing tissue death. This type usually occurs as a result of plaque build-up in arteries (atherosclerosis ) and develops over time.
Lacunar infarct (approx. 20 percent of cases) usually occurs as a result of arterial blockage caused by high blood pressure (hypertension). This type of stroke has the best prognosis.
A transient ischemic attack (TIA) is a transient event that is a risk factor for ischemic stroke. In a TIA, arterial blockage in the brain occurs briefly and resolves on its own, without causing tissue death. Approximately 10 percent of ischemic strokes are preceded by a TIA, and about 40 percent of patients who experience a TIA will have a stroke.