Monday, October 27, 2014

WHAT IS A STROKE ?



What is a Stroke?
Blood is carried to the brain via a complex network of arteries and vessels. A stroke occurs when one of these arteries becomes b ?locked or ruptures.

A stroke is a sudden interruption in the blood supply of the brain. Most strokes are caused by an abrupt blockage of arteries leading to the brain (ischemic stroke).  Other strokes are caused by bleeding into brain tissue when a blood vessel bursts (hemorrhagic stroke). Because stroke occurs rapidly and requires immediate treatment, stroke is also called a brain attack. When the symptoms of a stroke last only a short time (less than an hour), this is called a transient ischemic attack (TIA) or mini-stroke.

The effects of a stroke depend on which part of the brain is injured, and how severely it is injured. Strokes may cause sudden weakness, loss of sensation, or difficulty with speaking, seeing, or walking. Since different parts of the brain control different areas and functions, it is usually the area immediately surrounding the stroke that is affected. Sometimes people with stroke have a headache, but stroke can also be completely painless. It is very important to recognize the warning signs of stroke and to get immediate medical attention if they occur.

Types of Stroke
The most common type of stroke, accounting for almost 80 percent of all strokes, is caused by a clot or other blockage within an artery leading to the brain.
An intracerebral hemorrhage is a type of stroke caused by the sudden rupture of an artery within the brain. Blood is then released into the brain compressing brain structures.
A subarachnoid hemorrhage is also a type of stroke caused by the sudden rupture of an artery. A subarachnoid hemorrhage differs from an intracerebral hemorrhage in that the location of the rupture leads to blood filling the space surrounding the brain rather than inside of it.

Type of stroke:
1. Ischemic Stroke
An ischemic stroke occurs when an artery in the brain becomes blocked.

Ischemic (“is-skeem-ic”) stroke occurs when an artery to the brain is blocked.  The brain depends on its arteries to bring fresh blood from the heart and lungs. The blood carries oxygen and nutrients to the brain, and takes away carbon dioxide and cellular waste. If an artery is blocked, the brain cells (neurons) cannot make enough energy and will eventually stop working. If the artery remains blocked for more than a few minutes, the brain cells may die. This is why immediate medical treatment is critical.

What causes it?
Ischemic stroke can be caused by several different kinds of diseases. The most common problem is narrowing of the arteries in the neck or head. This is most often caused by atherosclerosis, or gradual cholesterol deposition. If the arteries become too narrow, blood cells may collect and form blood clots. These blood clots can block the artery where they are formed (thrombosis), or can dislodge and become trapped in arteries closer to the brain (embolism). Another cause of  stroke is blood clots in the heart, which can occur as a result of irregular heartbeat (for example, atrial fibrillation), heart attack, or abnormalities of the heart valves. While these are the most common causes of ischemic stroke, there are many other possible causes. Examples include use of street drugs, traumatic injury to the blood vessels of the neck, or disorders of blood clotting.

Types of ischemic stroke?
Ischemic stroke can be divided into two main types: thrombotic and embolic.

Deprived of oxygen and other nutrients, the brain suffers damage as a result of the stroke.
A thrombotic stroke occurs when diseased or damaged cerebral arteries become blocked by the formation of a blood clot within the brain. Clinically referred to as cerebral thrombosis or cerebral infarction, this type of event is responsible for almost 50 percent of all strokes. Cerebral thrombosis can also be divided into an additional two categories that correlate to the location of the blockage within the brain: large-vessel thrombosis and small-vessel thrombosis. Large-vessel thrombosis is the term used when the blockage is in one of the brain’s larger blood-supplying arteries such as the carotid or middle cerebral, while small-vessel thrombosis involves one (or more) of the brain’s smaller, yet deeper, penetrating arteries. This latter type of stroke is also called a lacuner stroke.
An embolic stroke is also caused by a clot within an artery, but in this case the clot (or emboli) forms somewhere other than in the brain itself. Often from the heart, these emboli will travel in the bloodstream until they become lodged and cannot travel any farther. This naturally restricts the flow of blood to the brain and results in near-immediate physical and neurological deficits.

Who gets it?
Ischemic stroke is by far the most common kind of stroke, accounting for about 88 percent of all strokes. Stroke can affect people of all ages, including children. Many people with ischemic strokes are older (60 or more years old), and the risk of stroke increases with age. Each year, about 55,000 more women than men have a stroke, and it is more common among African-Americans than members of other ethnic groups. Many people with stroke have other problems or conditions which put them at higher risk for stroke, such as high blood pressure (hypertension), heart disease, smoking, or diabetes. Read more about stroke risk factors and how to reduce your risk.

2. Intracerebral Hemorrhage
When blood vessels within the brain become damaged, they are more likely to burst and cause a hemorrhage.

Intracerebral hemorrhage occurs when a diseased blood vessel within the brain bursts, allowing blood to leak inside the brain. (The name means within the cerebrum or brain). The sudden increase in pressure within the brain can cause damage to the brain cells surrounding the blood. If the amount of blood increases rapidly, the sudden buildup in pressure can lead to unconsciousness or death. Intracerebral hemorrhage usually occurs in selected parts of the brain, including the basal ganglia, cerebellum, brain stem, or cortex.

What causes it?
The most common cause of intracerebral hemorrhage is high blood pressure (hypertension). Since high blood pressure by itself often causes no symptoms, many people with intracranial hemorrhage are not aware that they have high blood pressure, or that it needs to be treated. Less common causes of intracerebral hemorrhage include trauma, infections, tumors, blood clotting deficiencies, and abnormalities in blood vessels (such as arteriovenous malformations). View an interactive tutorial on arteriovenous malformations from the Toronto Brain Vascular Malformation Study Group.

Who gets it?
A ruptured blood vessel will leak blood into the brain, eventually causing the brain to compress due to the added amount of fluid.
Intracerebral hemorrhage occurs at all ages. The average age is lower than for ischemic stroke. Less common than ischemic strokes, hemorrhagic strokes make up about 12 percent of all strokes.

3. Subarachnoid Hemorrhage
When a cerebral aneurysm ruptures, blood will fill the space surrounding the brain.
Subarachnoid hemorrhage occurs when a blood vessel just outside the brain ruptures. The area of the skull surrounding the brain (the subarachnoid space) rapidly fills with blood. A patient with subarachnoid hemorrhage may have a sudden, intense headache, neck pain, and nausea or vomiting. Sometimes this is described as the worst headache of one’s life. The sudden buildup of pressure outside the brain may also cause rapid loss of consciousness or death.

What causes it?
Subarachnoid hemorrhage is most often caused by abnormalities of the arteries at the base of the brain, called cerebral aneurysms. These are small areas of rounded or irregular swellings in the arteries. Where the swelling is most severe, the blood vessel wall becomes weak and prone to rupture. View an interactive tutorial on cerebral aneurysms from the Toronto Brain Vascular Malformation Study Group.

Who gets it?
Surgical treatment of aneurysms involves placing clip on neck of aneurysm.
The cause of cerebral aneurysms is not known. They may develop from birth or in childhood and grow very slowly. Some people have multiple aneuryms. Subarachnoid hemorrhage can occur at any age, including in teenagers and young adults and is slightly more common in women than men.

How a Stroke is Diagnosed
If you have had a stroke, or have had stroke warning signs or risk factors, it is very important to seek prompt medical attention.  Your doctor will work with you to find the cause of your problem and determine the best treatment.  Even if your symptoms resolve without treatment, you should still discuss them with your doctor. Don’t assume that a problem is unimportant if it goes away on its own. Never try to make a diagnosis by yourself.

IMPORTANT:  If you or someone you know is having stroke symptoms now, call 911!  Stroke is a medical emergency.

The first step in understanding your problem is to obtain a careful medical history. Your doctor or health care provider will ask questions about your situation. If you can’t communicate, a family member or friend will be asked to provide this information. Your doctor will ask about the symptoms you are having now and have had in the past, previous medical problems or operations, and any illnesses which run in your family. Be sure to bring a current list of all the medicines you take (prescription and non-prescription.) If your symptoms lasted only a while, your doctor might also want to talk with someone else who was with you at the time.

The next step is a thorough physical examination. Your doctor will check your pulse and blood pressure, and examine the rest of your body (heart, lungs, etc). The neurologic examination includes detailed tests of your muscles and nerves. The doctor will check your strength, sensation, coordination and reflexes. In addition, you will be asked questions to check your memory, speech and thinking.

Depending on the results of your evaluation, your doctor may need additional tests to fully understand your problem. You may also be referred to a medical specialist in brain disorders (neurologist), brain surgery (neurosurgery) or another area. Be patient. Sometimes it takes a while to discover the cause of stroke symptoms, and sometimes the cause of a stroke cannot be determined. Be sure to discuss any questions or concerns with your doctor or health care provider.

Reducing Your Risk
If you have ever had a stroke or experience any of the warning signs of a stroke, it is very important that you work with your doctor to determine the most likely cause of the problem and the best course of treatment for you.

Certain medical conditions greatly increase your likelihood of having a stroke. Working with your doctor, you may need to begin specific medical treatment to control these risk factors.

Medical conditions that increase your stroke risk:
  • Previous stroke or “mini-stroke” (transient ischemic attack, TIA).
    Depending on the most likely cause of your stroke, your doctor may prescribe specific medication or consider surgery to remove fatty deposits in your carotid artery.
  • High blood pressure.
    Hypertension is one of the leading risks for heart disease and stroke. Your physician may advise dietary or lifestyle changes, or specific medications to lower your blood pressure. Take a look at
    “Your Guide to Lowering Blood Pressure” from the National Heart, Lung, and Blood Institute.
  • Diabetes.
    High blood sugar can increase your risk, so you should work closely with your doctor to manage it. Learn more about diabetes from the
    National Institute of Diabetes and Digestive and Kidney Diseases.
  • Heart disease.
    If you have an irregular heartbeat (atrial fibrillation), disease of the heart valves, congestive heart failure or have had a recent heart attack, your physician may prescribe medications to thin your blood and/or reduce your cholesterol level.
    Visit the
    National Heart, Lung, and Blood Institute for more information on cardiovascular disease.
Controllable risk factors and lifestyle choices:
  • Smoking.
    Tobacco use is a major preventable risk factor for stroke and heart disease. Even if you have smoked for years, you can still reduce your risk by quitting now.
    Need help quitting? The
    Freedom From Smoking® plan is free and available online at the American Lung Association.
  • Obesity, elevated cholesterol, and elevated lipids.
    Reducing your dietary intake of saturated fats and cholesterol may help reduce your risk of a stroke.
  • Physical inactivity.
    A sedentary lifestyle void of regular exercise can contribute to heart disease which may lead to stroke.
  • Excessive alcohol intake.
  • Illegal drug use.
Uncontrollable risk factors:
  • Increasing age.
    Stroke is more common in people over 60.
  • Male sex.
    Men and women both have strokes but stroke is more common at younger ages in men.
  • Heredity and ethnicity.
    Stroke is more common in people whose close relatives have had stroke at an early age. African-Americans and Hispanic Americans are at higher risk than white Americans. This may be due in part to high blood pressure and dietary differences.
Caregiver Introduction
Family caregivers and friends play a critical role in a loved one’s recovery from stroke, particularly as time spent in hospitals and rehabilitation facilities continues to decrease. Stroke recovery lasts for at least two years after stroke onset, so most of the support during this period comes from informal sources including friends and family members.

Providing care for a stroke patient can be an extremely rewarding experience. At the same time, it can be very stressful and frustrating to be suddenly thrust into the position of caregiver with little or no warning. It is crucial to remember to take care of your own needs in addition to those of the patient.
Also important to note is that stress tends to increase over time if the caregiver’s needs are not met. Some of those needs may include the need for information (especially better understanding of the emotional and behavioral changes of the patient), the need for skills in the physical aspects of care, and the need for support in the “case management” aspects of care. In terms of emotional reactions, caregivers often feel one or more of the following: anxiety, guilt, depression, frustration, resentment, impatience, and fear. (Fear that a stroke may happen again, fear that the stroke survivor may be unable to accept his or her disabilities, fear that the survivor may require nursing home placement, fear that the caregiver may make mistakes, and fear that families and friends will abandon them.) Coping with these reactions is paramount to a healthy caregiver, and ultimately, to a well-adjusted patient.


Source : internet stroke center

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