Stroke

Stroke

What is a stroke?

A stroke or "brain attack" occurs when a blood clot blocks an artery (a blood vessel that carries blood from the heart to the body) or a blood vessel (a tube through which the blood moves through the body) breaks, interrupting blood flow to an area of the brain. When either of these things happen, brain cells begin to die and brain damage occurs.

When brain cells die during a stroke, abilities controlled by that area of the brain are lost. These abilities include speech, movement and memory. How a stroke patient is affected depends on where the stroke occurs in the brain and how much the brain is damaged.

For example, someone who has a small stroke may experience only minor problems such as weakness of an arm or leg. People who have larger strokes may be paralyzed on one side or lose their ability to speak. Some people recover completely from strokes, but more than 2/3 of survivors will have some type of disability.

Causes :

Of the 2 main types of stroke, the ischemic stroke occurs 80-85% of the time. With an ischemic stroke, a blood vessel in the brain becomes clogged. With a hemorrhagic stroke, a blood vessel in the brain actually bursts or leaks.

Hemorrhagic strokes tend to be more serious. The distinction between type of stroke can be critical in determining the treatment used.

• Ischemic strokes occur when a blood vessel gets so narrow or clogged that not enough blood can get through to keep the brain cells alive.
  
  
  • Plaques (or build-up of cholesterol-containing fatty deposits calledarteriosclerosis) in the blood vessel walls can narrow the blood vessels that supply the brain. These plaques build up until the center of the blood vessel is so narrow that little, if any, blood can get past. Many things including high cholesterol and high blood pressurecause plaques. The plaques may occur in small vessels that supply only a very tiny portion of the brain but may also occur in the big blood vessels in the neck (carotids) or in the large arteries to the brain (cerebral arteries).
    
    
  • Ischemic strokes may also be caused by small blood clots or emboli that go through the bloodstream and then get clogged in an artery when the artery narrows. These clots can come from pieces of plaques in the bigger arteries that break off or from the heart.
  • [Ischaemic stroke]
  
  
• Hemorrhagic strokesoccur when the wall of a blood vessel becomes weak and blood leaks out into the brain.
• In addition to having decreased blood flow past the leak, the blood in the brain damages brain cells as it decomposes. If a lot of blood leaks out, it can cause a build-up of pressure in the brain because the brain is enclosed in the skull. There is not room for it to expand, and it cancompress and kill important areas of the brain.
  
  
• Hemorrhagic strokes tend to be more serious than ischemic strokes. Death occurs in 30-50% of people with this type of stroke.

[Hemorrhagic stroke]

Risk Factors :

Anyone can have a stroke no matter your age, race or gender. But, the chances of having a stroke increase if a person has certain risk factors, or criteria that can cause a stroke. The good news is that up to 80 percent of strokes can be prevented, and the best way to protect yourself and loved ones from stroke is to understand personal risk and how to manage it.

There are 2 types of risk factors for stroke: controllable and uncontrollable. Controllable risk factors generally fall into two categories: lifestyle risk factors or medical risk factors. Lifestyle risk factors can often be changed, while medical risk factors can usually be treated. Both types can be managed best by working with a doctor, who can prescribe medications and advise on how to adopt a healthy lifestyle. Uncontrollable risk factors include being over age 55, being male, being African American, Hispanic or Asian/Pacific Islander, or having a family history of stroke or transient ischemic attack (TIA).

Controllable Risk Factors: High Blood Pressure Atrial Fibrillation High Cholesterol Diabetes Tobacco Use and Smoking Alcohol Use Physical Inactivity Obesity Uncontrollable Risk Factors: Age Gender Race Family History Previous Stroke or TIA Fibromuscular Dysplasia Patent Foramen Ovale (PFO or Hole in the Heart)

Symptoms :

The symptoms of a stroke depend on what part of the brain and how much of the brain tissue is affected.

• Stroke symptoms usually come on suddenly-in minutes to an hour.
  
  
• There is usually no pain associated with the symptoms.
  
  
• The symptoms may come and go, go away totally, or get worse over the course of several hours.
  
  
• If the symptoms go away completely in a short time (fewer than 24 hours), the episode is called a transient ischemic attack (TIA).
  
  
• A third of all strokes occur during sleep, so people first notice the symptoms when they wake up.
  
  
• These are the common symptoms of stroke:
  
  
  • Weakness in the arm or leg or both on the same side:This can range from total paralysis to a very mild weakness. Complete numbness or a pins-and-needles feeling may be present on one side of your body or part of one side of your body.
    
    
  • Weakness in the muscles of the face: Your face may droop or look lopsided. Speech may be slurred because you can't control the movement of your lips or tongue.
    
    
  • Difficulty speaking: You can't speak, speech may be very slurred, or when you speak, the words sound fine but do not make sense.
    
    
  • Coordination problems:You may seem uncoordinated and stumble or have difficulty walking or difficulty picking up objects.
    
    
  • Dizziness: You may feel drunk or dizzy or have difficulty swallowing.
    
    
  • Vision problems: You may develop difficulty with vision, such as double vision, loss of peripheral (side) vision, or blindness. (Blurred vision by itself is not usually a symptom of stroke.)
    
    
  • Sudden headache: A sudden, severe headache may strike like "a bolt out of the blue." Some people have called this the worst headache of their lives.
    
    
  • Loss of consciousness:You may become unconscious, stuporous, or hard to arouse and could die.

What should be done if you suspect you or someone else is having a stroke?

If any of the symptoms mentioned above suddenly appear, emergency medical attention should be sought.Therefore, the first action should be to call 911(or whatever number activates the emergency medical response in your area). The family doctor and/or neurologist should also be contacted. However, the first priority is ensuring that the ambulance arrives as soon as possible.

• The affected person should lie flat to promote an optimal blood flow to the brain.
  
  
• If drowsiness, unresponsiveness, ornausea are present, the person should be placed in the rescue position on their side to prevent choking should vomiting occur.
  
  
• Although aspirin plays a major role in stroke prevention (see below), once the symptoms of a stroke begin, it is generally recommended that additional aspirin not be taken until the patient receives medical attention. If stroke is of the bleeding type, aspirin could theoretically make matters worse.

Cincinnati Prehospital Stroke Scale (CPSS)

According to a study by the University of North Carolina, three commands may be used to assess whether a person may be experiencing a stroke. Lay persons can command a potential stroke victim to:

1. Smile
   
   
2. Raise both arms
   
   
3. Speak a simple sentence

The three commands, known as the Cincinnati Prehospital Stroke Scale (CPSS), are used by health professionals as a simple first step in the assessment process for signs of stroke. If a person has trouble with any of these simple commands, emergency services should be called immediately with a description of the situation, noting that you suspect the individual is having a stroke.

Diagnosis :

Stroke is diagnosed through several techniques: a neurological examination, CT scans (most often without contrast enhancements) or MRI scans, Doppler ultrasound, and arteriography. The diagnosis of stroke itself is clinical, with assistance from the imaging techniques. Imaging techniques also assist in determining the subtypes and cause of stroke. There is yet no commonly used blood testfor the stroke diagnosis itself, though blood tests may be of help in finding out the likely cause of stroke.

Imaging

For diagnosing ischemic stroke in the emergency setting:

• CT scans (withoutcontrast enhancements)

sensitivity= 16%

specificity= 96%

• MRI scan

sensitivity= 83%

specificity= 98%

[Head CT showing deep intracerebral hemorrhage due to bleeding within thecerebellum, approximately 30 hours old]

For diagnosing hemorrhagic stroke in the emergency setting:

• CT scans (withoutcontrast enhancements)

sensitivity= 89%

specificity= 100%

• MRI scan

sensitivity= 81%

specificity= 100%

For detecting chronic hemorrhages, MRI scan is more sensitive.

For the assessment of stable stroke, nuclear medicine scans SPECT and PET/CT may be helpful. SPECT documents cerebral blood flow and PET with FDG isotope the metabolic activity of the neurons.

Underlying etiology

When a stroke has been diagnosed, various other studies may be performed to determine the underlying etiology. With the current treatment and diagnosis options available, it is of particular importance to determine whether there is a peripheral source of emboli. Test selection may vary, since the cause of stroke varies with age, comorbidity and the clinical presentation. Commonly used techniques include:

• an ultrasound/doppler study of the carotid arteries (to detect carotid stenosis) or dissection of the precerebral arteries
• an electrocardiogram (ECG) and echocardiogram (to identify arrhythmias and resultant clots in the heart which may spread to the brain vessels through the bloodstream)
• a Holter monitor study to identify intermittent arrhythmias
• an angiogram of the cerebral vasculature (if a bleed is thought to have originated from an aneurysm or arteriovenous malformation)
• blood tests to determine hypercholesterolemia, bleeding diathesis and some rarer causes such as homocysteinuria.

Treatment :

Medical Treatment

The initial treatment for stroke is supportive.

• You usually will be given fluids through an IV because if you're having a stroke, you may often be dehydrated.
  
  
• Oxygen may be given to be sure that your brain is getting the maximal amount.
  
  
• If you have any difficulty breathing, this will be assessed and treated.
  
  
• Unlike people with chest pain, people having a stroke are not given an aspirin immediately.
  
  
• You are requested not to eat or drink until your ability to swallow is assessed.
  
  
• Blood pressure control: It is important not to lower the blood pressure too much so that the brain will get enough blood. Many different medications can be used to lower the blood pressure including pills,nitroglycerin paste, or IV injections. If the blood pressure is very high, you would be placed on a continuous IV flow of medication.
  
  
  • Many people with stroke have very high blood pressure when they come to the emergency department. This may be due to an underlying problem or in response to the stroke. The doctor will assess the blood pressure and the type of stroke and decide if the blood pressure should be lowered.
  
  
• If you have acute stroke, you will be admitted to the hospital for monitoring and further testing to figure out the cause of the stroke and ways to prevent a future stroke. Once you have had a stroke, you are at greater risk than others of having an additional stroke.

Medications

• Drugs for acute stroke: Currently, only 1 medicine is approved to treat new strokes. It is the clot-busting medication calledtissue plasminogen activator (t-PA). This medicine works with the body's own chemicals and helps dissolve the blockage in the blood vessel in the brain that may be causing the stroke. It is the same drug that is often used to treat heart attacks. This is not a miracle drug, but studies of t-PA have shown that it can reduce disability from stroke by 30%. It has potentially serious side effects that include bleeding within the brain. This usually occurs in people who have serious strokes or who were not going to do well regardless of treatment (see the illustration of how effective this drug is). Not all people with stroke can receive the clot-busting drug t-PA.
  

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  • For t-PA to work, it must be given within 3 hours of the onset of symptoms. The earlier the drug is given within those 3 hours, the better it works. Symptom onset is defined as the time you were last known to be OK. If you awaken with symptoms, the symptom onset time is set back to the hour you went to sleep. This criterion alone may exclude many people from receiving this drug. This is also why it is so important to get to a stroke team for evaluation.
    
    
  • You must not have any evidence of bleeding on the CT scan of the head. The clot-busting medication is not used for anyone having a hemorrhagic stroke. That is why it is critical to know what kind of stroke you are having.
    
    
  • The doctor evaluates whether you should receive treatment with this drug and discuss the risks and benefits of giving it. Some doctors may believe that the drug is less effective. If given, strict guidelines must be met for the administration of this drug to prevent bad side effects.
  
  
• Other treatments for acute stroke are being tested. At some hospitals, clot-busting drugs are given through a small catheter that, through an IV, is threaded up into the neck and into the artery where there is a blockage. This treatment can potentially be used up to 6 hours after onset of stroke symptoms. Many other new treatments for stroke are being developed. It may be possible to participate in a study of a new stroke drug or other acute treatment.

Prevention :

Up to 80% of all strokes are preventable.

National Stroke Association's stroke prevention guidelines will help you learn how you may be able to lower your risk for a first stroke. The Stroke Prevention Guidelines were established by National Stroke Association's Stroke Prevention Advisory Board, an elite group of the nation's leading experts on stroke prevention. They were first published in a 1999 issue of Journal of the American Medical Association (JAMA) and have been updated to reflect current medical standards. National Stroke Association suggests you ask your doctor for advice on how to best use these guidelines.

Stroke Prevention Guidelines

Know your blood pressure. Find out if you have atrial fibrillation. If you smoke, stop. If you drink alcohol, do so in moderation. Find out if you have high cholesterol If you are diabetic... Exercise. Enjoy a lower sodium (salt), lower fat diet. Circulation (movement of the blood through the heart and blood vessels) problems. Know the Symptoms of Stroke. Stroke At A Glance : Stroke is the sudden death of brain cells due to lack of oxygen. Stroke is caused by the blockage of blood flow or rupture of an artery to the brain. Sudden tingling, weakness, or paralysis on one side of the body or difficulty with balance, speaking, swallowing, or vision can be a symptom of a stroke. Any person suspected of having a stroke or TIA should present for emergency care immediately Clot-busting drugs like TPA can be used to reverse a stroke, but the time frame for their use is very narrow. Patients need to present for care as soon as possible so that TPA therapy can be considered. Stroke prevention involves minimizing risk factors, such as controlling high blood pressure, elevated cholesterol, tobacco abuse, and diabetes.