Overview of Ischemic Stroke

An ischemic stroke occurs when a blood clot blocks blood flow in a vessel that is carrying blood to the brain. The most common risk factor for this type of stroke is high blood pressure. Approximately 80% of all strokes are ischemic strokes.

Comparison of a normal artery with an artery narrowed by atherosclerotic plaque
Encyclopaedia Britannica / UIG / Getty Images


There are two types of ischemic stroke: embolic stroke and thrombotic stroke.

Embolic Stroke

An embolic stroke occurs when an embolus, or a clot that moves through the bloodstream, forms in either the heart or neck arteries. It is then carried in the bloodstream where it blocks a blood vessel leading to or in the brain.

Thrombotic Stroke

A thrombotic stroke occurs when a blood clot, or thrombus, forms in an artery supplying blood to the brain. The blood clot blocks the flow of oxygen-rich blood to a portion of the brain. A thrombotic stroke may be preceded by a series of one or more transient ischemic attacks, also known as “mini-strokes” or TIAs.


Ischemic strokes are most often caused by arteries becoming narrowed, a condition known as atherosclerosis. Other causes include the use of recreational drugs, trauma to blood vessels in the neck, and blood clotting disorders.


When a person shows symptoms of a stroke or has a TIA (transient ischemic attack), the doctor will examine the patient in order to make a diagnosis. After obtaining a medical history, the following diagnostic tests may be performed:

  • Neurological examination
  • Complete blood count
  • CT scan
  • MRI scan


A person who is having a stroke may not notice that they are experiencing symptoms. If you think you are having stroke symptoms, or if you believe someone else is, a simple test is to think “FAST” and do the following:

  • Face: Ask the person to smile. Does one side of their face droop?
  • Arms: Ask the person to raise both arms. Does one of the arms drift downward or are they unable to raise either one of their arms?
  • Speech: Ask the person to repeat a simple phrase. Is their speech slurred?
  • Time: Seek immediate medical attention if you observe any of these signs.

Other symptoms of an ischemic stroke include:

  • Trouble understanding or speaking
  • Numbness of the arm, face, or leg
  • Blurred or blackened vision in one or both eyes
  • Double vision
  • Sudden, severe headache
  • Vomiting
  • Dizziness
  • Difficulty walking
  • Loss of balance or coordination


Immediate treatment is required to limit the level of brain damage that results from the blockage in blood flow. Treatment with tissue plasminogen activator, or tPA, has been effective for patients with an ischemic stroke as long as the patient has received it intravenously within three hours of the onset of symptoms.

Reducing Risk Factors

While certain risk factors as age, gender, heredity, and ethnicity are uncontrollable, a patient can reduce their risk of stroke by beginning treatment that controls their risk factors and adjusts their lifestyle choices.

Ways to control risk factors for a stroke include:

  • Quitting smoking
  • Losing weight
  • Increasing physical activity
  • Reducing alcohol intake
  • Eliminating illegal drug use
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  1. Boehme AK, Esenwa C, Elkind MS. Stroke risk factors, genetics, and preventionCirc Res. 2017;120(3):472-495. doi:10.1161/CIRCRESAHA.116.308398