In a thrombotic stroke, a blood clot (thrombus) forms inside one of the brain’s arteries. The clot blocks blood flow to a part of the brain. This causes brain cells in that area to stop functioning and die quickly.
The blood clot that triggers a thrombotic stroke usually forms inside an artery that already has been narrowed by atherosclerosis. This is a condition in which fatty deposits (plaques) build up inside blood vessels.
Thrombotic strokes can affect large or small arteries in the brain. Strokes that affect large arteries block flow to greater portions of the brain. These strokes tend to cause the most disability
When a thrombotic stroke occurs in a small artery, the artery is usually one that is deep within the brain. This stroke is more specifically named a lacunar stroke. Lacunar strokes often have minimal symptoms because only a small part of the brain is affected.
Another type of stroke — embolic stroke — is also caused by a blood clot. However, in an embolic stroke, the blood clot forms somewhere else in the body. It then travels through the bloodstream to the brain artery. The blood clot usually comes from the heart.