Types of Stroke
According to the CDC, every year about 610,000 people in the United States have a new stroke. Almost 130,000 of the 800,000 Americans who die of cardiovascular disease each year are killed by strokes —that’s 1 in every 19 deaths from all causes. Anyone, including children, can have a stroke, and there are different kinds of stroke that can occur. Read on to learn about the most common types and what the signs are that your or someone else may be having a stroke.
Most strokes (87%) that occur fall into the category of ischemic strokes. An ischemic stroke happens when blood flow through the artery that supplies blood to the brain becomes blocked. Ischemic strokes are primarily caused by blood clots and atherosclerosis, which is fatty deposits lining the vessel walls. According to the American Stroke Association, atherosclerosis can cause two types of obstruction:
- Cerebral thrombosis is a thrombus (blood clot) that develops at the fatty plaque within the blood vessel.
- Cerebral embolism is a blood clot that forms at another location in the circulatory system, usually the heart and large arteries of the upper chest and neck. Part of the blood clot breaks loose, enters the bloodstream and travels through the brain’s blood vessels until it reaches vessels too small to let it pass. A main cause of embolism is an irregular heartbeat called atrial fibrillation. This condition can cause clots to form in the heart, dislodge and travel to the brain.
Ischemic stroke can also occur in other scenarios, one of which is during a procedure involving a catheter, such as TAVI. During a TAVI procedure, a long flexible tube (catheter) is advanced through an artery (often through a small incision in the leg) to reach the aortic valve. Once in position, an artificial implantation valve at the tip of the catheter is expanded, pushing the diseased natural valve aside.
In the process of advancing the catheter and positioning the artificial implantation valve, embolic debris – calcium, tissue or other organic or foreign matter – may break loose and travel through the bloodstream toward the brain. If this matter sticks, it could potentially limit the blood and oxygen supply to the brain, which can lead to long-term damage. This can lead to a stroke, silent cerebral infarctions or other brain injury.
Silent cerebral infarction (SCI), or “silent stroke,” is a brain injury without the typical symptoms and sign of a stroke and is likely caused by a blood clot that interrupts blood flow in the brain. It’s a risk factor for future strokes and a sign of progressive brain damage.
Hemorrhagic stroke accounts for around 13% of all stroke and happens when a weakened vessel in the brain leaks blood or breaks open and bleeds into the surrounding brain. The leaked blood puts too much pressure on brain cells, which damages them.
There are two types of hemorrhagic strokes:
Intracerebral hemorrhage, the most common type, occurs when an artery in the brain bursts, flooding the surrounding tissue with blood. Two types of weakened blood vessels usually cause hemorrhagic stroke: aneurysms and arteriovenous malformations (AVMs).
The less common type of hemorrhagic stroke is called a subarachnoid hemorrhage. It refers to bleeding in the area between the brain and the thin tissues that cover it.
High blood pressure and aneurysms are examples of conditions that can cause a hemorrhagic stroke.
Transient Ischemic Attack (TIA)
A transient ischemic attack (TIA) is sometimes called a “mini-stroke.” It is a temporary blockage of blood flow, which is different than an ischemic or hemorrhagic stroke. In TIA, the blockage occurs for a short time, usually less than 5 minutes, and per definition symptoms and signs disappear within 24 hours. Similar to an ischemic stroke, TIAs can often be caused by a blood clot.
There isn’t a way to distinguish between a TIA and a major stroke in the beginning, since the symptoms and signs are identical. Although the blockage does not last as long and it does not typically cause permanent damage, it is important to treat it just as seriously and call 911. Having a TIA may signal a major stroke may happen in the future. According to the CDC, more than a third of people who have a TIA and don’t get treatment have a major stroke within 1 year. As many as 10% to 15% of people will have a major stroke within 3 months of a TIA. Recognizing and treating TIAs can lower the risk of a major stroke. If you have a TIA, your health care team can find the cause and take steps to prevent a major stroke.
The signs of a stroke
The American Stroke Association outlines the best method to determining stroke:
Use the letters in “F.A.S.T.” to spot stroke signs and know when to call 9-1-1
Face Drooping – Does one side of the face droop or is it numb? Ask the person to smile. Is the person’s smile uneven or lopsided?
Arm Weakness – Is one arm weak or numb? Ask the person to raise both arms. Does one arm drift downward?
Speech – Is speech slurred? Is the person unable to speak or hard to understand? Ask the person to repeat a simple sentence
Time to Call 9-1-1 – If the person shows any of these symptoms, even if the symptoms go away, call 9-1-1 and get them to the hospital immediately.
Additional Symptoms of Stroke:
- Sudden numbness or weakness of face, arm, or leg, especially on one side of the body
- Sudden confusion – trouble speaking or understanding speech
- Sudden trouble seeing in one or both eyes
- Sudden trouble walking, dizziness, loss of balance or coordination
- Sudden severe headache with no known cause
- Know the Facts about Stroke. Available at: https://www.cdc.gov/stroke/docs/ConsumerEd_Stroke.pdf. Accessed Feb. 22, 2019.
- Types of Strokes. Available at: https://www.strokeassociation.org/en/about-stroke/types-of-stroke. Accessed Feb. 22, 2019.
- Stroke Symptoms. Available at: https://www.strokeassociation.org/en/about-stroke/stroke-symptoms. Accessed Feb. 22, 2019.
- Type of Strokes. Available at: https://www.cdc.gov/stroke/types_of_stroke.htm. Accessed Feb. 22, 2019.
This educational blog was provided by Boston Scientific.