Causes - Stroke - Causes

There are two main types of stroke that have different causes. Ischemic strokes are caused by a blockage of a blood vessel. Hemorrhagic strokes are caused by sudden bleeding in the brain. Sometimes the doctor may not be able to figure out the cause of your stroke.

Ischemic stroke

Ischemic strokes are usually caused by a piece of plaque or a blood clot that blocks blood flow to the brain.

The illustration shows how an ischemic stroke can occur in the brain. If a blood clot breaks away from plaque buildup in a carotid artery in the neck, it can travel to an artery in the brain. The clot can block blood flow to part of the brain, causing brain tissue death
The illustration shows how an ischemic stroke can occur in the brain. If a blood clot breaks away from plaque buildup in a carotid artery in the neck, it can travel to an artery in the brain. The clot can block blood flow to part of the brain, causing brain tissue death.

Plaque buildup

When a fatty substance called plaque builds up on the inner walls of the arteries, it can lead to a disease called atherosclerosis. Plaque hardens and narrows the arteries, which limits blood flow to tissues and organs.

Plaque can build up in any artery in the body, including arteries in the brain and neck. Carotid artery disease is when plaque builds up in the carotid arteries in the neck that supply blood to the brain. It is a common cause of ischemic stroke.

Blood clots in the brain or elsewhere in the body

Plaque in an artery can break open. Blood platelets stick to the site of the plaque injury and clump together to form blood clots. These clots can partly or fully block an artery.

A blood clot that forms in one part of the body can also break loose and travel to the brain. This type of ischemic stroke is called an embolic stroke. Certain heart and blood conditions, such as atrial fibrillation and sickle cell disease, can cause blood clots that lead to stroke.

Inflammation

Chronic (long-term) inflammation contributes to ischemic stroke. Researchers are still trying to understand this fully. We know that inflammation can damage the blood vessels and contribute to atherosclerosis, however. In addition, ischemic stroke can lead to inflammation that further damages brain cells.

Transient ischemic attack

A transient ischemic attack (TIA) is caused by a blockage in the brain just like an ischemic stroke. But the blockage breaks up before there is any damage to your brain. It typically lasts less than an hour but can come and go. Eventually, it can progress to a full stroke. A TIA is also called a mini-stroke.

Hemorrhagic stroke

The illustration shows how a hemorrhagic stroke can occur in the brain. An aneurysm in a cerebral artery breaks open, which causes bleeding in the brain. The pressure of the blood causes brain tissue death.
The illustration shows how a hemorrhagic stroke can occur in the brain. An aneurysm in a cerebral artery breaks open, which causes bleeding in the brain. The pressure of the blood causes brain tissue death.

Sudden bleeding can cause a hemorrhagic stroke. This can happen when an artery in or on top of the brain breaks open. The leaked blood causes the brain to swell, putting pressure on it that can damage brain cells.

Some conditions make blood vessels in the brain more likely to bleed.

  • Aneurysm is a balloon-like bulge in an artery that can stretch and burst.
  • Arteriovenous malformations (AVMs) are tangles of poorly formed arteries and veins that can break open in the brain.
  • High blood pressure puts pressure on the inside walls of the arteries. This pressure makes them more likely to break open, especially when they are weakened because of an aneurysm or AVM.