MedLink Neurology is an interactive service for up-to-date information on clinical neurology. MedLink Neurology provides immediate access to an exclusive collection of more than 1000 in-depth, yet concise, clinical summaries on neurologic disorders and related topics. Written and kept up-to-date by experts, the clinical summaries contain links to thousands of abstracts and hundreds of informative videos and other illustrations in the MedLink library.

Stroke

What is a stroke/brain attack?
A stroke or brain attack occurs when a blood clot blocks a blood vessel or artery, or when a blood vessel breaks, interrupting blood flow to an area of the brain. When a brain attack occurs, it kills brain cells in the immediate area. Doctors call this area of dead cells an infarct. These cells usually die within minutes to a few hours after the stroke starts.

When brain cells in the infarct die, they release chemicals that set off a chain reaction called the "ischemic cascade." This chain reaction endangers brain cells in a larger, surrounding area of brain tissue for which the blood supply is compromised but not completely cut off. Without prompt medical treatment this larger area of brain cells, called the penumbra, will also die. Given the rapid pace of the ischemic cascade, the "window of opportunity" for interventional treatment is about six hours. Beyond this window, reestablishment of blood flow and administration of neuroprotective agents may fail to help and can potentially cause further damage.

When brain cells die, control of abilities which that area of the brain once controlled are lost. This includes functions such as speech, movement, and memory. The specific abilities lost or affected depend on where in the brain the stroke occurs and on the size of the stroke (i.e., the extent of brain cell death). For example, someone who has a small stroke may experience only minor effects such as weakness of an arm or leg. On the other hand, someone who has a larger stroke may be left paralyzed on one side or lose his/her ability to express and process language. Some people recover completely from less serious strokes, while other individuals lose their lives to very severe strokes.

Brain attack!
• Stroke is a "Brain Attack"
• Stroke happens in the brain rather than the heart.
• Stroke is an emergency!
• "Time is brain"


Why use the term brain attack?
The origination of the term "brain attack" and its application to stroke are credited to Vladimir C. Hachinski, M.D., and John Norris, M.D., both world-renowned neurologists from Canada. NSA began to champion the term in 1990 because it characterizes the medical condition and communicates the actual event more clearly to the public than does the word "stroke." The brain is the most delicate organ in the body. "To give the best chance of limiting damage, brain attacks should be heeded even more urgently than heart attacks," said Dr. Hachinski.

The symptoms of stroke should have the same alarming significance in identifying a brain attack that acute chest pain has in identifying a heart attack.

The public misperception that nothing can be done about stroke has prevailed for too long. With the use of the term "brain attack," we give stroke a definitive name and a unique face for the first time. Of all the images we use to identify stroke, "brain attack" is the most descriptive, realistic and powerful call to action. The appropriate response to a brain attack is emergency action, both by the person it strikes and the medical community.

Brain attack means medical emergency
Educating the public to treat stroke as a brain attack and to seek emergency treatment is crucial because every minute lost, from the onset of symptoms to the time of emergency contact, cuts into the limited window of opportunity for intervention. The majority of patients don't report to the emergency room until more than 24 hours after the onset of stroke symptoms. The longer the delay in patient presentation, the more damage a stroke can do and the less recovery can be achieved.

One of the largest obstacles to emergency treatment is that many people don't even know it when they are having a stroke. The University of Cincinnati reported that 52 percent of their acute stroke patients were unaware they were experiencing a stroke. Another factor in time of presentation is where people are when they have strokes. Those who have a brain attack in a public place where others may recognize the symptoms or see that something is wrong tend to report to the emergency room sooner. That is why it is critical for everyone to "Be Stroke Smart" and learn the 3 Rs of stroke: Reduce risk, Recognize symptoms, Respond by calling 911.

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

Call 911 if you see or have any of these symptoms. Treatment can be more effective if given quickly. Every minute counts!

Other important but less common stroke symptoms include:
• Sudden nausea, fever and vomiting distinguished from a viral illness by the speed of onset (minutes or hours vs. several days)
• Brief loss of consciousness or period of decreased consciousness (fainting, confusion, convulsions or coma)

Changing the perception of stroke

Myth Reality
* Stroke is unpreventable * Stroke is largely preventable
* Stroke cannot be treated * Stroke requires emergency treatment
* Stroke only strikes the elderly * Stroke can happen to anyone
* Stroke happens to the heart * Stroke is a "Brain Attack"
* Stroke recovery only happens for a few months following a stroke * Stroke recovery continues throughout life

Time to presentation
• 58% of stroke patients don't present until 24 hours or more after the onset
--Alberts et al, 1990
• 13 hours is median time from stroke onset to presentation
--Feldman et al, 1993
• 17% of adults over age 50 can't name a single stroke symptom
--NSA/Gallup Survey, 1996

Types of stroke
There are two main ways "brain attacks" can happen: ischemic and hemorrhagic strokes. In ischemic strokes, a blood clot blocks or "plugs" a blood vessel in the brain. In hemorrhagic strokes, a blood vessel in the brain breaks or ruptures.

Ischemic stroke
In everyday life, blood clotting is beneficial. When you are bleeding from a wound, blood clots work to slow and eventually stop the bleeding. In the case of stroke, however, blood clots are dangerous because they can block arteries and cut off blood flow, a process called ischemia. An ischemic stroke can occur in two ways: embolic and thrombotic strokes.

Embolic stroke
In an embolic stroke, a blood clot forms somewhere in the body (usually the heart) and travels through the bloodstream to your brain. Once in your brain, the clot eventually travels to a blood vessel small enough to block its passage. The clot lodges there, blocking the blood vessel and causing a stroke. The medical word for this type of blood clot is embolus.

Thrombotic stroke
In the second type of blood-clot stroke, blood flow is impaired because of a blockage to one or more of the arteries supplying blood to the brain. The process leading to this blockage is known as thrombosis. Strokes caused in this way are called thrombotic strokes. That's because the medical word for a clot that forms on a blood-vessel deposit is thrombus.

Blood-clot strokes can also happen as the result of unhealthy blood vessels clogged with a buildup of fatty deposits and cholesterol. Your body regards these buildups as multiple, tiny and repeated injuries to the blood vessel wall. So your body reacts to these injuries just as it would if you were bleeding from a wound it responds by forming clots.

Two types of thrombosis can cause stroke large vessel thrombosis and small vessel disease (or lacunar infarction).

Large vessel thrombosis
Thrombotic stroke occurs most often in the large arteries, so large vessel thrombosis is the most common and best understood type of thrombotic stroke. Most large vessel thrombosis is caused by a combination of long-term atherosclerosis followed by rapid blood clot formation. Thrombotic stroke patients are also likely to have coronary artery disease, and heart attack is a frequent cause of death in patients who have suffered this type of brain attack.

Small vessel disease/Lacunar infarction
Small vessel disease, or lacunar infarction, occurs when blood flow is blocked to a very small arterial vessel. The term's origin is from the Latin word lacuna which means hole, and describes the small cavity remaining after the products of deep infarct have been removed by other cells in the body. Little is known about the causes of small vessel disease, but it is closely linked to hypertension.

Hemorrhagic stroke
Strokes caused by the breakage or "blowout" of a blood vessel in the brain are called hemorrhagic strokes. The medical word for this type of breakage is hemorrhage. Hemorrhages can be caused by a number of disorders which affect the blood vessels, including long-standing high blood pressure and cerebral aneurysms. An aneurysm is a weak or thin spot on a blood vessel wall. These weak spots are usually present at birth. Aneurysms develop over a number of years and usually don't cause detectable problems until they break. There are two types of hemorrhagic stroke: subarachnoid and intracerebral.

In an intracerebral hemorrhage, bleeding occurs from vessels within the brain itself. Hypertension is the primary cause of this type of hemorrhage.

In a subarachnoid hemorrhage (SAH), an aneurysm bursts in a large artery on or near the thin, delicate membrane surrounding the brain. Blood spills into the area around the brain which is filled with a protective fluid, causing the brain to be surrounded by blood-contaminated fluid.

The FDA recently issued a voluntary recall of non-prescription medications containing PPA (phenylpropanolamine) after they were linked to an increased risk of hemorrhagic stroke in women.

Classification of hemorrhagic strokes
• Hemorrhagic strokes are divided into two types, named for the part of the brain where they occur. An intracerebral hemorrhage(ICH) is characterized by bleeding into the brain itself, while a subarachnoid hemorrhage (SAH) describes bleeding into the area that surrounds the brain. While these two types of hemorrhagic stroke are similar, they generally arise from different causes and produce different outcomes.

• An understanding of hemorrhagic stroke offers hope for reducing the death and disability that results from the disease. Read on to learn more about how a hemorrhagic stroke occurs, the risk factors you should be aware of, and some of the treatment methods doctors use.

Effects of stroke
The ability to define the world and our place in it distinguishes our humanity. Stroke or brain attack forever alters this world-making capacity. The stroke patient's world, once comprehensible and manageable, is transformed into a confusing, intimidating and hostile environment. The skills of intellect, sensation, perception and movement, which are honed over the course of a lifetime and which so characterize our humanity are the very abilities most compromised by stroke. Stroke can rob people of the most basic methods of interacting with the world.

The specific abilities that will be lost or affected by stroke depend on the extent of the brain damage and most importantly where in the brain the stroke occurred. The brain is an incredibly complex organ, and each area within the brain has responsibility for a particular function or ability. The brain is divided into four primary parts: the right hemisphere (or half), the left hemisphere, the cerebellum and the brain stem.

Right-hemisphere stroke
The right hemisphere of the brain controls the movement of the left side of the body. It also controls analytical and perceptual tasks, such as judging distance, size, speed, or position and seeing how parts are connected to wholes.

A stroke in the right hemisphere often causes paralysis in the left side of the body. This is known as left hemiplegia. Survivors of right-hemisphere strokes may also have problems with their spatial and perceptual abilities. This may cause them to misjudge distances (leading to a fall) or be unable to guide their hands to pick up an object, button a shirt or tie their shoes. They may even be unable to tell right-side up from upside-down when trying to read.

Along with their impaired ability to judge spatial relationships, survivors of right-hemisphere strokes often have judgment difficulties that show up in their behavioral styles. These patients often develop an impulsive style unaware of their impairments and certain of their ability to perform the same tasks as before the stroke. This behavioral style can be extremely dangerous. It may lead the left hemiplegic stroke survivor to try to walk without aid. Or it may lead the survivor with spatial and perceptual impairments to try to drive a car.

Survivors of right-hemisphere strokes may also experience left-sided neglect. Stemming from visual field impairments, left-sided neglect causes the survivor of a right-hemisphere stroke to "forget" or "ignore" objects or people on their left side.

Finally, some survivors of right-hemisphere strokes will experience problems with short-term memory. Although they may be able to recount a visit to the seashore that took place 30 years ago, they may be unable to remember what they ate for breakfast that morning.

Left-hemisphere stroke
The left hemisphere of the brain controls the movement of the right side of the body. It also controls speech and language abilities for most people. A left-hemisphere stroke often causes paralysis of the right side of the body. This is known as right hemiplegia.

Someone who has had a left-hemisphere stroke may also develop aphasia. Aphasia is a catch-all term used to describe a wide range of speech and language problems. These problems can be highly specific, affecting only one component of the patient's ability to communicate, such as the ability to move their speech-related muscles to talk properly. The same patient may be completely unimpaired when it comes to writing, reading or understanding speech.

In contrast to survivors of right-hemisphere stroke, patients who have had a left-hemisphere stroke often develop a slow and cautious behavioral style. They may need frequent instruction and feedback to complete tasks.

Finally, patients with left-hemisphere stroke may develop memory problems similar to those of right-hemisphere stroke survivors. These problems can include shortened retention spans, difficulty in learning new information and problems in conceptualizing and generalizing.

Cerebellar stroke
The cerebellum controls many of our reflexes and much of our balance and coordination. A stroke that takes place in the cerebellum can cause abnormal reflexes of the head and torso, coordination and balance problems, dizziness, nausea and vomiting.

Brain stem stroke
Strokes that occur in the brain stem are especially devastating. The brain stem is the area of the brain that controls all of our involuntary, "life-support" functions, such as breathing rate, blood pressure and heartbeat. The brain stem also controls abilities such as eye movements, hearing, speech and swallowing. Since impulses generated in the brain's hemispheres must travel through the brain stem on their way to the arms and legs, patients with a brain stem stroke may also develop paralysis in one or both sides of the body.

Recovery & rehabilitation
Current statistics indicate that there are nearly 4 million people in the United States who have survived a stroke and are living with the after-effects. These numbers do not reflect the scope of the problem and do not count the millions of husbands, wives and children who live with and care for stroke survivors and who are, because of their own altered lifestyle, greatly affected by stroke.

The very word "stroke" indicates that no one is ever prepared for this sudden, often catastrophic event. Stroke survivors and their families can find workable solutions to most difficult situations by approaching every problem with patience, ingenuity, perseverance and creativity.

Early recovery
There's still so much we don't know about how the brain compensates for the damage caused by stroke or brain attack. Some brain cells may be only temporarily damaged, not killed, and may resume functioning. In some cases, the brain can reorganize its own functioning. Sometimes, a region of the brain "takes over" for a region damaged by the stroke. Stroke survivors sometimes experience remarkable and unanticipated recoveries that can't be explained. General recovery guidelines show:

• 10 percent of stroke survivors recover almost completely
• 25 percent recover with minor impairments
• 40 percent experience moderate to severe impairments requiring special care
• 10 percent require care in a nursing home or other long-term care facility
• 15 percent die shortly after the stroke

Rehabilitation
Rehabilitation actually starts in the hospital as soon as possible after the stroke. In patients who are stable, rehabilitation may begin within two days after the stroke has occurred, and should be continued as necessary after release from the hospital.

Depending on the severity of the stroke, rehabilitation options include:
• A rehabilitation unit in the hospital
• A subacute care unit
• A rehabilitation hospital
• Home therapy
• Home with outpatient therapy
• A long-term care facility that provides therapy and skilled nursing care

The goal in rehabilitation is to improve function so that the stroke survivor can become as independent as possible. This must be accomplished in a way that preserves dignity and motivates the survivor to relearn basic skills that the stroke may have taken away - skills like eating, dressing and walking.

Types of rehabilitation
There are three primary means of rehabilitation.

Physical therapy (PT) helps restore physical functioning and skills like walking and range of movement. Major impairments which PT works on include partial or one-sided paralysis, faulty balance and foot drop.

Occupational therapy (OT) involves relearning the skills needed for everyday living such as eating, toileting, dressing and taking care of oneself.

Speech language pathology is another major rehabilitative therapy. Some stroke survivors are left with aphasia, an impairment of language and speaking skills in which the stroke survivor can think as well as before the stroke, but is unable to get the right words out or is unable to process words coming in. Aphasia is usually caused by a stroke on the left side of the brain. Speech language pathology can teach the aphasic stroke survivor and his or her family members methods for coping with this frustrating impairment. Speech language pathologists also work to help the stroke survivor cope with memory loss and other "thought" problems caused by the stroke.

Stroke risk factors and their impact
Stroke is one of the most preventable of all life-threatening health problems. The two primary types of risk factors for stroke are those that are controllable and those that are not. It's important to remember that having one or more uncontrollable stroke risk factors DOES NOT MAKE A PERSON FATED TO HAVE A STROKE. With proper attention to controllable stroke risk factors, the impact of uncontrollable factors can be greatly reduced.

Uncontrollable stroke risk factors
Uncontrollable stroke risk factors include:
Age - The chances of having a stroke go up with age. Two-thirds of all strokes happen to people over age 65. Stroke risk doubles with each decade past age 55.

Gender - Males have a slightly higher stroke risk than females. But, because women in the United States live longer than men, more stroke survivors over age 65 are women.

Race - African-Americans have a higher stroke risk than most other racial groups.

Family history of stroke or TIA - Risk is higher for people with a family history of stroke or TIA.

Personal history of diabetes - People with diabetes have a higher stroke risk. This may be due to circulation problems that diabetes can cause. In addition, brain damage may be more severe and extensive if blood sugar is high when a stroke happens. Treating diabetes may delay the onset of complications that increase stroke risk. However, even if diabetics are on medication and have blood sugar under control, they may still have an increased stroke risk simply because they have diabetes.

Controllable stroke risk factors
Treatable medical disorders that increase stroke risk include:
High blood pressure - Having high blood pressure, or hypertension, increases stroke risk four to six times. It is the single most important controllable stroke risk factor. High blood pressure is often called "the silent killer" because people can have it and not realize it, since it often has no symptoms. Hypertension is a common condition, affecting approximately 50 million Americans, or one-third of the adult population. Blood pressure is considered pre-hypertensive if it is consistently more than 120/80. It is classified as Stage One Hypertnesion if it is over 140/90. Between 40 and 90 percent of all stroke patients had high blood pressure before their stroke. Hypertension puts stress on blood vessel walls and can lead to strokes from blood clots or hemorrhage.

Atrial fibrillation and other heart diseases - Heart disease such as atrial fibrillation increases stroke risk up to six times. About 15 percent of all people who have a stroke have a heart disease called atrial fibrillation, or AF, which affects approximately 2.2 million Americans. AF is caused when the atria (the two upper chambers of the heart) beat rapidly and unpredictably, producing an irregular heartbeat. AF raises stroke risk because it allows blood to pool in the heart. When blood pools, it tends to form clots which can then be carried to the brain, causing a stroke.

Normally, all four chambers of the heart beat in the same rhythm somewhere between 60 and 100 times every minute. In someone who has AF, the left atrium may beat as many as 400 times a minute. If left untreated, AF can increase stroke risk four to six times. Long-term untreated AF can also weaken the heart, leading to potential heart failure. The prevalence of AF increases with age. AF is found most often in people over age 65 and in people who have heart disease or thyroid disorders. Among people age 50 to 59, AF is linked to 6.7 percent of all strokes. By ages 80-89, AF is responsible for 36.2 percent of all strokes.

Coronary heart disease and high cholesterol - High cholesterol can directly and indirectly increase stroke risk by clogging blood vessels and putting people at greater risk of coronary heart disease, another important stroke risk factor. A cholesterol level of more than 200 is considered "high." Cholesterol is a fatty substance in the blood that our bodies make on their own, but we also get it from fat in the foods we eat. Certain foods (such as egg yolks, liver or foods fried in animal fat or tropical oils) contain cholesterol. High levels of cholesterol in the blood stream can lead to the buildup of plaque on the inside of arteries, which can clog arteries and cause heart or brain attack.

Sleep disordered breathing - sleep apnea - Sleep apnea is a major cardiovascular and stroke risk factor increasing blood pressure rates which may cause stroke or heart attack. Studies also indicate that people with sleep apnea develop dangerously low levels of oxygen in the blood while carbon dioxide levels rise, possibly causing blood clots or even strokes to occur. Diagnosing sleep apnea early may be an important stroke prevention tool.

Personal history of stroke or TIA - People who have already had a stroke or TIA are at risk for having another. After suffering a stroke, approximately 5 to 14 percent of survivors will have another stroke within one year. The rate of having another stroke is about 10 percent per year thereafter. (Sacco et. al. Survival and Recurrence Following Stroke; The Framingham Study) TIAs are also strong predictors of stroke because 35 percent of those who experience TIAs have a stroke within five years.

Lifestyle factors that increase stroke risk include
Smoking - Smoking doubles stroke risk. Smoking damages blood vessel walls, speeds up the clogging of arteries by deposits, raises blood pressure and makes the heart work harder.

Alcohol - Excessive consumption of alcohol is associated with stroke in a small number of research studies. Its specific role in stroke has not yet been determined or proven. Recent studies have also suggested that modest alcohol consumption (one 4 oz. glass of wine or the alcohol equivalent) may protect against stroke by raising levels of a naturally occurring "clot-buster" in the blood.

Weight - Excess weight puts a strain on the entire circulatory system. It also makes people more likely to have other stroke risk factors such as high cholesterol, high blood pressure and diabetes.

This information was developed by the National Stroke Association and is herewith used with permission.

National Stroke Association. All About Stroke. Available at: http://199.239.30.192/NationalStroke/AllAboutStroke/default.htm. Last accessed June 4, 2004.

The information in this document is for general educational purposes only. It is not intended to substitute for personalized professional advice. Although the information was obtained from sources believed to be reliable, MedLink Corporation, its representatives, and the providers of the information do not guarantee its accuracy and disclaim responsibility for adverse consequences resulting from its use. For further information, consult a physician and the organization referred to herein.

CopyrightŠ MedLink Corporation 1993-2005 All Rights Reserved

This site is developped by Massoud Bina, M.D. and Morteza Bina, Ph.D. All rights reserved. Copyright ©2005. Site Administrator: morteza@massoudbina.com