Definition

Stroke is a brain injury that occurs when the brain's blood supply is interrupted. Without oxygen and nutrients from blood, brain tissue starts to die rapidly (usually in less than 10 minutes), resulting in a sudden loss of function.

Also known "brain attack" or cerebrovascular accident (CVA).

Causes

A stroke most often occurs when blood flow to the brain becomes blocked (called ischemic stroke). One of the following may cause this blockage:

  • A build-up of fatty substances (atherosclerotic plaque) along the inner lining of the artery causes it to narrow, reduces its elasticity, and decreases its blood flow
  • A clot forms in an artery supplying the brain. Due to conditions in which blood quickly clots, such as during pregnancy, clot form somewhere in the body (often the heart) and break free, traveling to and becoming lodged in an artery supplying the brain.
  • Inflammatory conditions in the blood vessels (vasculitis) interrupting blood flow

A stroke may also occur if a blood vessel breaks and bleeds into or around the brain, this is called hemorrhagic stroke.

Hemorrhagic vs. Ischemic Stroke

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Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

Risk factors include:

Modifiable risk factors:

  • High blood pressure , the number one risk factor for ischemic stroke
  • High blood homocysteine level
  • Drug abuse (heroin, cocaine , amphetamines)
  • Narrowing of arteries supplying the brain due to atherosclerosis
  • High cholesterol levels , particularly low-density lipoprotein (LDL) cholesterol
  • Smoking
  • Diabetes mellitus
  • Atrial fibrillation (abnormality of heart rhythm)
  • Use of birth control pills if you are over 35 years old and smoke

Nonmodifiable risk factors:

  • A prior stroke or pre-existing cardiovascular disease such as heart attack other than stroke
  • A prior transient ischemic attack (a temporary interruption of the brain's blood supply, often called a mini-stroke)
  • Age: 60 or older
  • Family members who have had a stroke
  • Gender: males are at greater risk than females
  • Race: Black , Asian, Hispanic
  • Blood disorders which increase clotting in sickle cell disease and polycythemia
  • Valvular disease such as mitral stenosis

Some patients experience a "warning stroke" or transient ischemic attack (TIA). These are symptoms of a stroke that resolve completely, usually within minutes. Such patients are at a significantly increased risk of having a full-blown stroke sometime in the near future.

Symptoms

Symptoms occur suddenly and differ depending on the part of the brain affected. Multiple symptoms generally arise simultaneously. Do not delay calling for emergency medical help. Brain tissue dies quickly when deprived of oxygen.

Symptoms include:

  • Weakness or numbness on one side of the body, including the face
  • Seizures
  • Confusion
  • Nausea and vomiting of sudden onset
  • Blurry, dimming, double vision, or no vision
  • Difficulty swallowing, talking, or comprehending others
  • Dizziness, falling, or loss of balance
  • Severe or unusual headache

Diagnosis

Having a stroke is an emergency situation. Diagnosis includes:

  • Neurological exams
  • Electrocardiogram (ECG, EKG) –a test that records the heart's activity by measuring electrical currents through the heart muscle
  • Blood tests especially homocysteine, prothrombin time, and other coagulation tests
  • Imaging scans
  • Other tests to quickly determine the cause, location, and amount of damage

Some tests may include:

CT scan—a type of x-ray that uses a computer to make pictures of the brain. This test helps doctors sort out hemorrhagic versus ischemic stroke.

MRI scan—a test that uses magnetic waves to make pictures of the brain

Arteriography (Angiography)—shows arteries in the brain

Magnetic resonance angiography (MRA)—shows brain blood vessels by mapping blood flow

Functional MRI—shows brain activity by picking up signals from oxygenated blood

Doppler ultrasound—shows narrowing of the arteries supplying the brain

Echocardiography—a test that uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart. This test shows if the clot comes from one of the heart's chambers.

Treatment

Immediate treatment is needed to:

  • Dissolve a clot causing an ischemic stroke
  • Stop the bleeding during a hemorrhagic stroke

Other stroke care aims to:

  • Reduce the chance of subsequent strokes
  • Improve functioning
  • Overcome disabilities

Medications

Medications include:

  • Clot-dissolving drugs—given within three hours of the onset of symptoms. (Note: Only in carefully selected patients.) Tissue plasminogen activator (tPA) is given through a vein after the doctor has confirmed the stroke's cause and there is no evidence of bleeding.
  • Blood-thinning drugs (Anticoagulants)—heparin is given by vein (along with tPA, if indicated) and an oral medication (warfarin) is sometimes started if long-term treatment with a blood-thinner is anticipated.
  • Antiplatelet drug— aspirin is the most common, but clopidogrel (Plavix), dipyridamole (Persantine), and ticlopidine (Ticlid) are also sometimes used.

Other drugs are used to:

  • Control blood pressure (usually use Labetalol, the first-line drug, or sodium nitroprusside)
  • Reduce chance of additional clot formation (aspirin or similar medications)
  • Reduce brain swelling
  • Correct irregular heart rhythm (such as atrial fibrillation)

Other interventions during an acute stroke include:

  • Providing adequate oxygen
  • Taking precautions to prevent choking
  • Frequent neurological examinations

Surgery

Surgery may be performed following a stroke or TIA to prevent a recurrence. Surgical techniques include:

Carotid endarterectomy—fatty deposits are removed from a carotid artery (major arteries in the neck that lead to the brain)

Carotid angioplasty and stenting—in a less invasive procedure than carotid endarterectomy, the carotid artery is widened and a metallic mesh tube and filter is inserted into the artery to help keep it open

Extracranial/intracranial bypass—reroutes the blood supply around a blocked artery using a healthy scalp artery

Recently, a study was conducted comparing endarterectomy and stenting in 527 patients who recently suffered a minor stroke or TIA and had severe carotid artery narrowing (at least 60%). Even though endarterectomy is more invasive (and dangerous) than stenting, endarterectomy led to fewer deaths and repeat strokes than stenting within the first six months. *

Rehabilitation

Rehabilitation may include:

  • Physical therapy
  • Occupational therapy
  • Speech therapy

Prevention

The following may help prevent a stroke:

  • Exercise regularly.
  • Increase intake of fruits and vegetables and limit dietary salt and fat.
  • Stop smoking.
  • If you drink alcohol, drink alcohol only in moderation (1-2 drinks per day).
  • Maintain a healthy weight.
  • Frequently check blood pressure and follow physician recommendations for keeping it in a safe range.
  • Consider taking a low dose of aspirin (75 milligrams per day) if your physician determines it is safe.
  • Keep chronic medical conditions under control (such as high cholesterol and diabetes).
  • Seek medical care if you have symptoms of a stroke, even if symptoms stop.
  • Stop the use of recreational drugs (cocaine, heroin, marijuana, amphetamines)