Types of Stroke
An ischemic stroke most often occurs when blood flow to the brain becomes blocked. One of the following events may cause this blockage:
- The most common cause is a build-up of fatty substances (atherosclerotic plaque) along an artery's inner lining that causes it to narrow, reduces its elasticity, and decreases its blood flow.
- A clot forms in an artery supplying the brain, usually one affected by atherosclerosis.
- A clot forms somewhere in the body (often the heart) and breaks free, traveling to and becoming lodged in an artery supplying the brain. This clot is called an embolus, and the process is called embolism.
A stroke may also occur if a blood vessel breaks and bleeds into or around the brain; this is called hemorrhagic stroke. Trauma, cocaine abuse, and high blood pressure are the leading causes of hemorrhagic strokes, which occur more commonly in younger people. Aneurysms predispose you to hemorrhagic stroke. An aneurysm is a weak spot in an artery that balloons out under pressure and can rupture, causing bleeding into the brain.