Ischemic strokes account for about 87 percent of all stroke cases. The usually occur at night or first thing in the morning. An Ischemic stroke occurs when blood vessels to the brain become narrowed or clogged, cutting off blood flow to brain cells. The most important risk factor for ischemic stroke that you can control is high blood pressure.

Symptoms of an ischemic stroke develop over a few minutes or worsen over hours. They may be preceded by symptoms or warning signs that may include loss of strength or sensation on one side of the body, problems with speech and language or changes in vision or balance.

There are three types of ischemic strokes:

• Thrombotic strokes are caused by a blood clot in an artery going to the brain. The clot blocks the blood flow. Blood clots usually form in arteries damaged by arteriosclerosis.
• Embolic strokes are caused by a wandering clot that has formed in another part of the body and carried in the blood stream eventually clogging a blood vessel in or leading to the brain.
• Systemic hypoperfusion (low blood flow) occurs because of circulatory failure caused by the heart itself. The heart’s pumping action fails and too little blood reaches the brain. This is how a heart attack may cause a stroke.

Ischemic strokes are usually treated with clot busting drugs. Tissue plasminogen activator (tPA) is very effective but must be administered within a three-hour window.