Types of Stroke
Ischemic Stroke
Approximately 80% 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). Types of ischemic stroke include embolic infarct, thrombotic infarct, and lacunar infarct. Infarct of undetermined cause accounts for approximately 30% 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 20-30% of ischemic strokes.
Thrombotic infarct (approx. 10-15% 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% 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% of ischemic strokes are preceded by a TIA, and about 40% of patients who experience a TIA will have a stroke.
