A stroke is the interruption of the blood supply to the brain that is caused by a blockage or bleeding in the brain.
Stroke is the leading cause of permanent disability in the United States.
Many of the risk factors for stroke can be controlled or eliminated.
A stroke occurs when blood flow to the brain is interrupted. If the brain lacks sufficient blood for a long enough period of time, brain damage or death can result.
There are two major types of stroke:
Ischemic stroke, in which an artery becomes blocked; and
Hemorrhagic, or bleeding, stroke.
Ischemic stroke is the most common type. Blockages can occur if major arteries in the neck or the arteries in the brain become narrowed by atherosclerosis. Usually, a piece of plaque or a blood clot that lodges in the narrowed artery causes the blockage. Sometimes the arteries themselves block blood flow if enough plaque builds up in the artery walls.
Approximately 10 to 15 percent of strokes are hemorrhagic. In hemorrhagic stroke, a blood vessel inside the brain leaks or bursts. Hemorrhagic strokes are more deadly than ischemic strokes.
WHAT ARE THE SYMPTOMS?
Symptoms of stroke vary but usually come on suddenly.
Most stroke-related brain damage occurs within a few hours of the onset of symptoms. Patients who experience any of the following symptoms should seek help immediately:
Partial loss of vision in one eye;
Weakness, tingling, or numbness in a limb;
Temporary loss of control of movement in a limb;
Inability to speak clearly;
Unsteadiness, vertigo, double vision, or sudden falls;
Loss of balance;
Personality or mood changes;
Drowsiness or loss of consciousness; and
Uncontrollable eye movements or eye drooping.
Hemorrhagic strokes can also cause the following symptoms:
Sudden and severe headache;
Nausea or vomiting; and
CAUSES AND RISK FACTORS
High blood pressure increases the risk of hemorrhagic strokes.
Atherosclerosis commonly causes ischemic strokes.
Causes of hemorrhagic stroke include:
High blood pressure;
Anticoagulant medications; and
Factors that increase the risk of strokes include:
African American race;
Family history of stroke;
Prior heart attack or stroke;
Alcohol or drug abuse; and
Obesity and lack of exercise.
To diagnose stroke, the physician will obtain a detailed description of the patient's symptoms and perform physical and neurological examinations.
Tests that the physician may order include:
Computed tomography (CT) scan;
Magnetic resonance imaging (MRI);
Transcranial Doppler ultrasound;
Electroencephalogram (EEG); or
Evoked response test.
Patients who experience stroke are usually treated in the intensive care unit.
Ischemic stroke and hemorrhagic stroke are treated differently. Generally, physicians treat an ischemic stroke by removing the blockage that is preventing blood flow in the brain. The physician administers clot-dissolving drugs through the bloodstream to remove the blockage.
Endovascular treatments that use tiny devices to retrieve clots in the brain are being studied for ischemic stroke.
Several treatments may be used to prevent ischemic stroke, including:
Anticoagulant or antiplatelet medications;
Angiotensin-converting enzyme (ACE) inhibitors;
Carotid endarterectomy; and
To treat hemorrhagic stroke, physicians create an obstruction in the damaged blood vessel to stop bleeding using surgery or minimally invasive treatments.