Stroke

What is stroke?

A stroke, or brain attack, is caused by the sudden loss of blood flow to the brain or bleeding inside the head. Each can cause brain cells to stop functioning or die. When brain cells die, the function of body parts they control is impaired or lost, causing paralysis, speech problems, loss of feeling, memory and reasoning deficits, coma, and possibly death. Every year, about 550,000 people in the United States suffer a stroke, and about 150,000 die, making it the nationís number three killer after heart disease and cancer. It is the number one cause of adult disability. Stroke risk increases sharply with age, doubling every decade after the age of 55. However, stroke can occur at any age- approximately 28 percent of those who have a stroke are under 65 years old.

Fortunately, by recognizing the signs of stroke and seeking immediate medical attention you can help reduce your chances of death and disability.

What are the symptoms?

Stroke symptoms may not be as dramatic or painful as a heart attack, but the results can be just as devastating. Stroke is an emergency. Get medical attention immediately and know when the symptoms started. Common symptoms include:

  • Sudden weakness, numbness, or paralysis of the face, arm, or leg (especially on one side of the body)
  • Sudden loss of speech or difficulty talking
  • Sudden difficulty understanding language or confusion
  • Sudden loss of vision (in one eye or loss of vision to one side) or blurred vision
  • Sudden, severe headache with no apparent cause
  • Sudden loss of balance or coordination, often associated with dizziness

Call 911 immediately if you or someone you know experiences any of the above warning signs. Jot down the time the symptoms started. Sometimes these warning signs occur for only a few minutes and then resolve. Even if this happens, or if you think you are getting better, call for help.

What causes a brain attack?

Ischemic stroke is cause by an interruption of blood flow to the brain, while hemorrhagic stroke is caused by bleeding inside the head. The following defines the various types of stroke:

  • Ischemic- blockage of brain blood vessels, including:
    • Embolic- clots travel from the heart or neck blood vessels and lodge in the brain
    • Lacunar- small vessels in the brain are blocked, often due to high blood pressure or diabetes damage
    • Thrombotic- clot forms in the brain blood vessels often due to arteriosclerosis
  • Hemorrhagic- bleeding into or around the brain, including:
    • Subarachnoid- weak spots on brain arteries burst and blood covers the brain
    • Bleeding into the brain- blood vessels in the brain break because they have been weakened by damage due to high blood pressure, diabetes, and aging

When blood cannot get to the brain cells, they die within minutes to a few hours. Doctors call this area of dead cells an infarct.

The lack of normal blood flow to brain cells sets off a chain reaction called the "ischemic cascade." Over hours, this chain reaction endangers brain cells in a progressively larger area of brain where blood supply is compromised but not completely cut off. Prompt medical treatment offers the best chance of salvaging this region of brain cells, called the "penumbra."

What are the treatments

Immediate medical care is critical. New treatments work only if given within a few hours after the onset of a stroke. For example, a clot-busting drug recently approved by FDA must be given within three hours.

Before treatment, the neurologist or emergency physician must carefully examine the patient to determine the patientís condition and what caused the stroke. Diagnostic tests to determine treatment could include:

  • Neurologic exam
  • Brain imaging tests to determine the type, location and extent of the stroke (CT and MRI scans)
  • Tests that show blood flow and bleeding sites (angiography and carotid and transcranial ultrasound)
  • Blood tests for blleding or clotting disorders
  • EKG or an ultrasound examination of the heart (echocardiogram) to identify cardiac sources of blood clots that can travel to the brain
  • Tests that gauge impairments on a functional scale

Once the doctor completes these tests, the treatment is selected. For all stroke patients, the aim is to prevent further brain damage. If the stroke is caused by blockage of blood to the brain, treatment could include:

  • Drugs that thin the blood, including anticoagulants (coumadin) and antiplatelet medications (aspirin or ticlopidine)
  • Drugs that break up clots (thrombolytics)
  • Surgery that cleans the insides of blood vessels (endarterectomy)
  • Drugs that stop the chain reaction of damage from the ischemic cascade (neuroprotective agents, promising but still experimental)
  • Procedures which dilate blocked blood vessels

If the stroke is caused by bleeding, treatment could include:

  • Drugs that maintain normal blood clotting
  • Surgery to remove blood in the brain or decrease pressure on the brain
  • Surgery to fix the broken blood vessels
  • Blocking off bleeding vessels with a balloon or coil
  • Drugs that prevent or reverse brain swelling

After having a stroke, many people will be left with some disability. The disability depends on the size and location of the stroke. The right side of the brain controls the left side of the body and in right-handed individuals it is important for attention and visual-spatial skills. The left side of the brain controls the right side of the body and in right-handed individuals (and 50 percent of left-handed individuals) controls language- speaking and understanding. Language disorders are also called "aphasias."

Rehabilitation helps restore functions lost from damage due to stroke. During rehabilitation, most patients will improve to some degree, but many do not recover completely. Unlike skin cells, brain cells that die do not recover and are not replaced by new cells. However, the human brain is adaptable and patients can learn new ways of functioning, using other, undamaged brain cells. This stage is often a challenge as the patient and family work as part of the medical team.

A stroke patientís rehabilitation team may include physical, occupational, and speech therapists; nurses; and doctors. Most of the improvement will take place in the first three to six months of the rehabilitation process, but some patients can make excellent progress over longer periods of time.

How is stroke prevented?

Some risk factors- age, sex, race, and a history of stroke in the family-cannot be changed, but others can be controlled. Most controllable risk factors relate to the health of the heart and blood vessels. The following can help prevent stroke:

  • Regular medical check-ups
  • Controlling high blood pressure
  • Donít smoke- if you do smoke, stop
  • Treating heart disease, especially an irregular heart beat called atrial fibrillation (AF)
  • Improving diet: Avoid excess fat, salt, and alcohol
  • Exercising
  • Controlling diabetes
  • Seeking immediate medical attention for warning signs of stroke

Progress through research

A massive effort is underway throughout the United States and the world, involving thousands of scientists studying all aspects of stroke: genetic factors; new diagnostic tools to detect early stroke; drugs and techniques to prevent or reduce stroke; drugs to improve stroke recovery; new ways of opening blocked blood vessels; and improved methods in prevention and rehabilitation. To date, the most significant progress has been increased understanding and prevention of the causes of stroke and improved emergency care of stroke patients. Much of this process and all new treatments have come from studies using animal models of stroke. Continues research is needed and should improve prevention and survival of stroke.

 
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