Updated February 02, 2015.

An ischemic stroke is a type of stroke that results from a lack of blood supply to the brain. This is different from a hemorrhagic stroke, which is caused by bleeding in the brain. About 70-80% of strokes are ischemic strokes, while some strokes have ischemic and hemorrhagic characteristics, and others are hemorrhagic.

Ischemia can occur in any part of the body, including the brain, when an artery that supplies a region of the body with blood is blocked by a blood clot or damaged in a way that interrupts blood flow.

Blood that flows through arteries carries red blood cells that deliver oxygen to nearby cells. Blood that flows through arteries also delivers water, nutrients, and minerals to all of the cells in the body, while removing excess waste material. So an interruption of blood supply has serious consequences because every cell in the body needs oxygen, water, nutrients and minerals to survive. Ischemia can occur in any part of the body, and when it occurs in the brain, it is called an ischemic stroke.

The Damage Caused by Ischemia is Called Infarct

Usually if ischemia lasts for more than a few minutes, harmful biological changes begin to take place. These biochemical changes damage the brain through a process that is referred to as an infarction, or infarct. A brain infarct results in changes of structure and function of brain cells. The changes are produced by inflammation and the release of toxins that damage the cells, as well as a discharge of excess fluid that causes swelling, and alterations in the blood vessels.

The time course of the chemical injury of a brain infarct begins within minutes after ischemia, worsens within a few hours and continues to develop over 24-48 hours. Eventually, severe permanent damage may occur to the affected region of the brain if blood flow is not restored. Therefore, immediate recognition of stroke symptoms and prompt medical attention can save lives and prevent serious disability from a stroke.

When a region of the brain undergoes an infarct, people experience neurological symptoms because of the loss of function of the impaired region of the brain. The neurological symptoms correspond to the damaged area of the brain.

Recent scientific research studies have allowed doctors to carefully observe and better understand the process of ischemia, which helps in developing better treatments for neuro protection for stroke patients. Research in the area of stroke neuro protection may eventually lead to ways to diminish or even eliminate the damage caused by a stroke.

Temporary Ischemia

When ischemia occurs, and then quickly reverses, people experience a temporary stroke, often referred to as a mini-stroke. This is called a transient ischemic attack, or TIA, because the ischemia is only transient and does not last for long enough to cause permanent damage. However, if you experience a TIA, it is critical to recognize that this is a warning sign indicating that you are at risk of a stroke, and to get medical attention immediately.

Risk factors

Risk factors for ischemic stroke include any disease that increases the predisposition to abnormal blood clot formation or any disease that damages the inner lining of arteries in the brain (cerebral arteries), which makes them more likely to clog up. Heart disease, high cholesterol, smoking, cerebrovascular disease, hypertension, poorly controlled diabetes and blood-clotting disorders are all risk factors for ischemic stroke.

Treatment of ischemic stroke

Urgent treatment for ischemic stroke includes careful monitoring and management of blood pressure and blood sugar and possibly administration of strong blood thinners. Long-term treatment of ischemic stroke includes maintaining optimal blood pressure, management of heart disease, blood sugar control, lowering cholesterol and possibly taking blood thinners to prevent the development of harmful blood clots. Certain habits, such as diet, exercise and smoking can have a huge impact on the likelihood of ischemic stroke.

Sources:

Therapeutic efficacy of brain imaging in acute ischemic stroke patients, Von Kummer R, Dzialowski I, Gerber J, Journal of Neuroradiology, November 2014

Time course of neuronal death following endothelin-1 induced focal ischemia in rats, Nguemeni C, Gomez-Smith M, Jeffers M, Schuch CP, Corbett D, Journal of Neuroscience Methods, January 2015