Definition

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 (in 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:
  • 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
      • Blood protein defects leading to increased clotting tendency
      • 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

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© 2009 Nucleus Medical Media, 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:

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. They may signal 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
  • 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. Also, multiple symptoms can happen at the same time. If you notice any of the symptoms below, call emergency help right away. Getting help immediately is important, because brain tissue dies quickly when deprived of oxygen.

  • Sudden weakness or numbness of face, arm, or leg, especially on one side of the body
  • Sudden confusion
  • Sudden trouble speaking or understanding
  • Sudden trouble seeing in one or both eyes
  • Sudden dizziness, trouble walking, loss of balance, or coordination
  • Sudden severe headache with no known cause

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, 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 blood vessels feeding the brain
  • Blood tests, especially homocysteine, prothrombin time, and other coagulation tests

Some tests may include:

  • Arteriography (angiography)—a catheter is placed in a blood vessel in the groin and threaded up to the brain, shows arteries in the brain
  • Magnetic resonance angiography (MRA)—shows brain blood vessels by mapping blood flow
  • CT angiogram (CTA)—this test uses a CT scanner, gives images of the blood vessels inside the brain after a dye is injected into the veins
  • Functional MRI—shows brain activity by picking up signals from oxygenated blood
  • Doppler ultrasound—shows narrowing of the arteries (carotid and vertebral) supplying the brain, evaluates flow of blood in brain
  • Echocardiography—a test that uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart, 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 shortly after the start of symptoms—typically given within 3 hours by IV, or intraarterially (IA) within 6 hours
    • Used in carefully selected patients
  • Blood-thinning drugs (anticoagulants)
    • Heparin, given by vein
    • Oral medicine (warfarin), given if long-term treatment with blood-thinner is expected
    • Lovenox or other related medicines, given subcutaneously (under skin)
  • Antiplatelet drugs

Other drugs are used to:

Other interventions during an acute stroke:

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

Surgery

Some procedures can be done to prevent damage or allow blood flow back into the affected area after a stroke:

  • Extracranial/intracranial bypass—blood supply is rerouted around a blocked artery using a healthy scalp artery
  • Craniotomy—done with a hemorrhagic stroke to relieve pressure build-up in the brain caused by swelling
  • Embolectomy—a catheter is threaded through blood vessels to the clot; a special device will either mechanically remove the clot or deliver clot-dissolving medicine directly to the area

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

  • Carotid endarterectomy—fatty deposits are removed from a carotid artery (major arteries in the neck that lead to the brain)
  • Carotid angioplasty and stenting—less invasive procedure, carotid artery is widened and a mesh tube is placed into the artery to keep it open

A study was done to compare endarterectomy to stenting. Even though endarterectomy is more invasive, it led to fewer deaths. It also had fewer repeat strokes than stenting within the first six months.

Rehabilitation

  • Physical therapy—to regain as much movement as possible
  • Occupational therapy—to assist in everyday tasks and self care
  • Speech therapy—to improve swallowing and speech challenges
  • Psychological therapy—to improve mood and decrease depression

Prevention

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

  • Exercise regularly.
  • Eat more fruits and vegetables. Limit dietary salt and fat.
  • Stop smoking.
  • Increase your consumption of fish.
  • Drink alcohol only in moderation (1-2 drinks per day).
  • Maintain a healthy weight.
  • Check blood pressure frequently. Follow your doctor's recommendations for keeping it in a safe range.
  • Take a low dose of aspirin (50-325 milligrams per day) if your doctor says it is safe.
  • Keep chronic medical conditions under control. This includes high cholesterol and diabetes.
  • Talk to your doctor about the use of a statins. These types of drugs may help prevent certain kinds of strokes in some people.
  • Seek medical care if you have symptoms of a stroke, even if symptoms stop.
  • Stop the use of recreational drugs (cocaine, heroin, marijuana, amphetamines).