Stroke is a brain injury. It occurs when the brain's blood supply is interrupted. Without oxygen and nutrients from blood, brain tissue dies quickly (less than 10 minutes). This causes a sudden function loss.

Causes
A stroke occurs when blood flow to the brain is blocked (called ischemic stroke). This is caused by one of the following:

Sudden decreased blood flow
Damage to a blood vessel supplying blood to the brain can occur suddenly from either:

• Injury
• A clot that forms and breaks off from another part of the body (such as the heart or neck)
• There are certain conditions which predispose people to form blood clots, such as:
  • Cancer
  • Pregnancy
  • Atrial fibrillation
  • Certain autoimmune diseases

Local blood clot
A build-up of fatty substances (atherosclerotic plaque) along the inner lining of the artery causes:

• Narrowing of artery
• Reduced elasticity
• Local inflammation
• Decreased blood flow in the artery
• Clot in an artery supplying the brain
• Inflammatory conditions in the blood vessels (vasculitis)

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

© 2009 Nucleus Medical Art, Inc.
Risk Factors
These risk factors increase your chance of developing a stroke. Tell your doctor if you have any of these risk factors.

Risk factors you can affect:

• 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
• Long-term use of hormone replacement therapy*

Risk factors you cannot affect:

• Prior stroke or pre-existing cardiovascular disease such as heart attack
• Prior transient ischemic attack (TIA)
  • Some people experience a "warning stroke" or TIA. This is a temporary interruption of the brain's blood supply (mini-stroke). These are stroke symptoms that resolve completely within minutes. There may be a very high risk of having a full-blown stroke in the near future.
• 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 heart disease such as mitral stenosis

Symptoms
Symptoms occur suddenly. They differ depending on the part of the brain affected. Multiple symptoms arise at the same time. Call emergency help right away. Brain tissue dies quickly when deprived of oxygen.

Symptoms:

• Weakness or numbness on one side of the body, including the face
• Seizures
• Confusion
• Sudden nausea and vomiting
• 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.
• Brain and blood vessel imaging by:
  • CT scan, a type of x-ray that uses a computer to make pictures of the brain.
    • This test helps doctors identify hemorrhagic versus ischemic stroke.
  • MRI scan, a test that uses magnetic waves to make pictures of the brain.
  • Ultrasonography, a test that uses sound waves to examine the brain.
• Blood tests especially homocysteine, prothrombin time, and other coagulation tests.

Some tests may include:

• 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 treatment aims to:

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

Medications

Clot-dissolving drugs

• Given within three hours of the start of symptoms
• Used in carefully selected patients

Blood-thinning drugs (anticoagulants)

• Heparin given by vein
• Oral medication (warfarin) given if long-term treatment with blood-thinner is expected

Antiplatelet drugs

• Aspirin
• Clopidogrel (Plavix), dipyridamole (Persantine), and ticlopidine (Ticlid)

Other drugs are used to:

• Control blood pressure (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 (eg, atrial fibrillation)

Other interventions during an acute stroke:

• Adequate oxygen
• Precautions to prevent choking
• Frequent neurological examinations

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

• Carotid endarterectomy. The surgeon removes fatty deposits from a carotid artery (major arteries in the neck that lead to the brain).
• Carotid angioplasty and stenting. This is a less invasive procedure than carotid endarterectomy. The surgeon widens the carotid artery. He inserts a mesh tube into the artery to keep it open.
• Extracranial/intracranial bypass. The surgeon reroutes the blood supply around a blocked artery using a healthy scalp artery.
• Craniotomy. In the case of a hemorrhagic stroke, the surgeon relieves pressure build-up in the brain caused by swelling.

A study compared 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

• Physical therapy
• Occupational therapy
• Speech therapy

Prevention
To help reduce your chance of getting a stroke, take the following steps:

• Exercise regularly.
• Eat more fruits and vegetables and limit dietary salt and fat.
• Stop smoking.
• Drink alcohol only in moderation (1-2 drinks per day).
• Maintain a healthy weight.
• Frequently check blood pressure and follow doctor recommendations for keeping it in a safe range.
• Take a low dose of aspirin (75 milligrams per day) if your doctor says 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).