Ischemic Stroke
Overview
Ischemic strokes occur when blood supply is cut off to part of the brain. This type of stroke accounts for the majority of all strokes.
The blocked blood flow in an ischemic stroke may be caused by a blood clot or by atherosclerosis, a disease which causes narrowing of the arteries over time. Ischemic strokes can be caused by a blockage anywhere along the arteries feeding the brain.
Immediate emergency treatment is critical to surviving a stroke with the least amount of damage to the brain and ability to function.
Symptoms
Most ischemic strokes occur rapidly, over minutes to hours, and immediate medical care is vital. If you notice one or more of these signs in another person or in yourself, do not wait to seek help. Call 9-1-1 immediately.
The signs of a stroke are:
- Sudden numbness or weakness of the face, arm or leg, especially on one side of the body
- Sudden confusion
- Sudden trouble speaking
- Sudden trouble seeing in one or both eyes
- Sudden trouble walking
- Sudden dizziness, loss of balance or coordination
- Sudden, severe headache with no known cause
The effects of an acute ischemic stroke may cause additional symptoms in women including:
- Face, arm or leg pain
- Hiccups or nausea
- Chest pain or palpitations
- Shortness of breath
Not all symptoms occur with every stroke, and sometimes they go away and return.
Some patients experience symptoms that clear up within only a few minutes, which may be a sign of a transient ischemic attack (TIA). This is known to be one of the early warning signs of a stroke.
Causes
Ischemic strokes occur when blood supply is cut off to part of the brain by a blood clot or narrowing of the arteries.
Blood clots may be caused by an irregular heartbeat such as arrhythmia, problems with the heart valve, infection of the heart muscle, hardening of the arteries, blood-clotting disorders, inflammation of the blood vessels, or a heart attack.
A less common cause of ischemic stroke occurs when blood pressure becomes too low (hypotension), reducing blood flow to the brain. This usually occurs with narrowed or diseased arteries. Low blood pressure can result from a heart attack, large loss of blood or severe infection. Each of these conditions affects the flow of blood through the heart and blood vessels and increases the risk of stroke.
Risk factors
Strokes can happen to a person of any age, including children. However, the older a person is, the higher their risk of stroke. Strokes are more common in men, but more women die from them. A family history of stroke, or a personal history of stroke or heart attack, also increase the risk of stroke. Research also has shown African-Americans are at higher risk of stroke than Caucasians.
The top preventable risk factor for stroke is smoking. Quitting smoking is a far more powerful way to prevent stroke than any other pill or procedure.
Uncontrolled high blood pressure, diabetes, coronary artery disease and high blood cholesterol are all risk factors for stroke.
In people younger than 50, the more common causes of stroke also include migraine, drug abuse, consumption of "energy" drinks or herbal supplements, and arterial dissection, which occurs when a small tear forms in the innermost lining of the artery wall allowing blood to leak into the space between the inner and outer layers of the vessel.
Diagnosis
Diagnosis of an ischemic stroke usually is based on a detailed history of events and a physical examination. The Stroke Program at Cedars-Sinai accesses myriad diagnostic services to produce a detailed diagnosis, and allow for the best possible course of treatment.
In general, if a stroke is suspected, imaging tests, including magnetic resonance imaging (MRI) and computed tomography (CT) scans, will be done to produce a detailed picture of the brain.
Further testing may include:
- Electrical activity tests, including electroencephalogram (EEG) and evoked potential tests
- Blood flow tests, including angiography and echocardiography
Some diagnostic tests may be done to see if other conditions are present, check the person's overall health and see if the patient's blood clots too easily.
Treatment
People who have symptoms of a stroke need emergency medical care. Immediate medical attention may prevent life-threatening complications, more widespread brain damage, and is critical for the recovery.
If emergency treatment is sought for ischemic stroke within the first three hours after symptoms begin, the patient may receive a medication to dissolve the clot, such as tissue plasminogen (tPA), which can increase the chances of a full recovery. A surgical procedure, known as thrombectomy, also may reverse stroke symptoms.
Medication may be given to treat brain swelling or pressure that can occur after a stroke. Many effects of a stroke require oxygen or an intravenous line to provide the patient with fluids and nourishment.
Removing blood vessel blockages after a small stroke or transient ischemic attack (TIA) may reduce the risk of future strokes. In this case, carotid artery stenting or treating aneurysms or arteriovenous malformations may be recommended. Additional treatments of acute ischemic strokes vary according to the underlying cause.
The goals of treatment are to prevent life-threatening complications that may occur soon after stroke symptoms develop, prevent future strokes, reduce disability, prevent long-term complications and help the patient get back as much normal functioning as possible through rehabilitation.
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