stroke

Stroke Know the signs & symptoms of stroke.

More about Stroke: Causes and symptoms Diagnosis Treatment Prognosis Prevention Resources

Definition

A stroke is the sudden death of brain cells in a localized area due to inadequate blood flow.

Description

A stroke occurs when blood flow is interrupted to part of the brain. Without blood to supply oxygen and nutrients and to remove waste products, brain cells quickly begin to die. Depending on the region of the brain affected, a stroke may cause paralysis, speech impairment, loss of memory and reasoning ability, coma, or death. A stroke is also sometimes called a brain attack or a cerebrovascular accident (CVA).

Some important stroke statistics:

• more than half a million people in the United States experience a new or recurrent stroke each year
• stroke is the third leading cause of death in the United States and the leading cause of disability
• stroke kills about 150, 000 Americans each year, or almost one out of three stroke victims
• three million Americans are currently permanently disabled from stroke
• in the United States, stroke costs about $30 billion per year in direct costs and loss of productivity
• two-thirds of strokes occur in people over age 65
• strokes affect men more often than women, although women are more likely to die from a stroke
• strokes affect blacks more often than whites, and are more likely to be fatal among blacks

Stroke is a medical emergency requiring immediate treatment. Prompt treatment improves the chances of survival and increases the degree of recovery that may be expected. A person who may have suffered a stroke should be seen in a hospital emergency room without delay. Treatment to break up a blood clot, the major cause of stroke, must begin within three hours of the stroke to be effective. Improved medical treatment of all types of stroke has resulted in a dramatic decline in death rates in recent decades. In 1950, nine in ten died from stroke, compared to slightly less than one in three today.

— Richard Robinson

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n.

1. The act or an instance of striking, as with the hand, a weapon, or a tool; a blow or impact.
2. 1. The striking of a bell or gong.
   2. The sound so produced.
   3. The time so indicated: at the stroke of midnight.
3. A sudden action or process having a strong impact or effect: a stroke of lightning.
4. A sudden occurrence or result: a stroke of luck; a stroke of misfortune.
5. A sudden severe attack, as of paralysis or sunstroke.
6. A sudden loss of brain function caused by a blockage or rupture of a blood vessel to the brain, characterized by loss of muscular control, diminution or loss of sensation or consciousness, dizziness, slurred speech, or other symptoms that vary with the extent and severity of the damage to the brain. Also called cerebral accident, cerebrovascular accident.
7. An inspired or effective idea or act: a stroke of genius.
8. 1. A single uninterrupted movement, especially when repeated or in a back-and-forth motion: the stroke of a pendulum.
   2. Any of a series of movements of a piston from one end of the limit of its motion to another.
9. 1. A single completed movement of the limbs and body, as in swimming or rowing.
   2. The manner or rate of executing such a movement: My favorite stroke is butterfly. She had a very rapid stroke.
10. Nautical.
    1. The rower who sits nearest the coxswain or the stern and sets the tempo for the other rowers.
    2. The position occupied by this person.
11. Sports.
    1. A movement of the upper torso and arms for the purpose of striking a ball, as in golf or tennis.
    2. The manner of executing such a movement.
    3. A scoring unit in golf counted for such a movement: finished six strokes under par.
12. 1. A single mark made by a writing or marking implement, such as a pen.
    2. The act of making such a mark.
    3. A printed line in a graphic character that resembles such a mark.
13. A distinctive effect or deft touch, as in literary composition.

v., stroked, strok·ing, strokes.

v.tr.

1. 1. To mark with a single short line.
   2. To draw a line through; cancel: stroked out the last sentence.
2. Nautical. To set the pace for (a rowing crew).
3. To hit or propel (a ball, for example) with a smoothly regulated swing.

v.intr.

1. To make or perform a stroke.
2. Nautical. To row at a particular rate per minute.

[Middle English, probably from Old English *strāc.]

stroke² (strōk)
tr.v., stroked, strok·ing, strokes.

1. To rub lightly, with or as if with the hand or something held in the hand; caress.
2. Informal. To behave attentively or flatteringly toward, especially in order to restore to confidence or win over.

n.
A light caressing movement, as of the hand.

[Middle English stroken, from Old English strācian, from *strāc, stroke. See stroke¹.]

stroker strok'er n.

stroke

For more information on stroke, visit Britannica.com.

Definition

A stroke is the sudden death of brain cells in a localized area due to inadequate blood flow.

Description

A stroke occurs when blood flow is interrupted to part of the brain. Without blood to supply oxygen and nutrients and to remove waste products, brain cells quickly begin to die. Depending on the region of the brain affected, a stroke may cause paralysis, speech impairment, a loss of memory and reasoning ability, coma, or death. A stroke is also sometimes called a brain attack or a cerebrovascular accident (CVA).

Some important stroke statistics include:

• More than half a million people in the United States experience a new or recurrent stroke each year.
• Stroke is the third leading cause of death in the United States and the leading cause of disability.
• Stroke kills about 150,000 Americans each year, or almost one out of three stroke victims.
• Three million Americans are currently permanently disabled from stroke.
• In the United States, stroke costs about $30 billion per year in direct costs and loss of productivity.
• Two-thirds of strokes occur in people over age 65.
• Strokes affect men more often than women, although women are more likely to die from a stroke.
• Strokes affect blacks more often than whites, and are more likely to be fatal among blacks.

Stroke is a medical emergency requiring immediate treatment. Prompt treatment improves the chances of survival and increases the degree of recovery that may be expected. A person who may have suffered a stroke should be seen in a hospital emergency room without delay. Treatment to break up a blood clot, the major cause of stroke, must begin within three hours of the stroke to be effective. Improved medical treatment of all types of stroke has resulted in a dramatic decline in death rates in recent decades. In 1950, nine in 10 people died from stroke, compared to slightly less than one in three today.

Causes and symptoms

Causes

There are four main types of stroke. Cerebral thrombosis and cerebral embolism are caused by blood clots that block an artery supplying the brain, either in the brain itself or in the neck. These account for 70–80% of all strokes. Subarachnoid hemorrhage and intracerebral hemorrhage occur when a blood vessel bursts around or in the brain.

Cerebral thrombosis occurs when a blood clot, or thrombus, forms within the brain itself, blocking the flow of blood through the affected vessel. Clots most often form due to "hardening" (atherosclerosis) of brain arteries. Cerebral thrombosis occurs most often at night or early in the morning. Cerebral thrombosis is often preceded by a transient ischemic attack (TIA), sometimes called a "mini-stroke." In a TIA, blood flow is temporarily interrupted, causing short-lived stroke-like symptoms. Recognizing the occurrence of a TIA and seeking immediate treatment are important steps in stroke prevention.

Cerebral embolism occurs when a blood clot from elsewhere in the circulatory system breaks free. If it becomes lodged in an artery supplying the brain, either in the brain or in the neck, it can cause a stroke. The most common cause of cerebral embolism is atrial fibrillation, a disorder of the heartbeat. In atrial fibrillation, the upper chambers (atria) of the heart beat weakly and rapidly, instead of slowly and steadily. Blood within the atria is not completely emptied. This stagnant blood may form clots within the atria, which can then break off and enter the circulation. Atrial fibrillation is a factor in about 15% of all strokes. The risk of a stroke from atrial fibrillation can be dramatically reduced with daily use of anticoagulant medication.

Hemorrhage, or bleeding, occurs when a blood vessel breaks, either from trauma or excess internal pressure. The vessels most likely to break are those with preexisting defects such as an aneurysm. An aneurysm is a "pouching out" of a blood vessel caused by a weak arterial wall. Brain aneurysms are surprisingly common. According to autopsy studies, about 6% of all Americans have them. Aneurysms rarely cause symptoms until they burst. Aneurysms are most likely to burst when blood pressure is highest, and controlling blood pressure is an important preventive strategy.

Intracerebral hemorrhage affects vessels within the brain itself, while subarachnoid hemorrhage affects arteries at the brain's surface, just below the protective arachnoid membrane. Intracerebral hemorrhages represent about 10% of all strokes, while subarachnoid hemorrhages account for about 7%.

In addition to depriving affected tissues of blood supply, the accumulation of fluid within the inflexible skull creates excess pressure on brain tissue, which can quickly lead to death. Nonetheless, recovery may be more complete for a person who survives hemorrhage than for one who survives a clot, because the blood deprivation effects are usually not as severe.

Death of brain cells triggers a chain reaction in which toxic chemicals created by cell death affect other nearby cells. This is one reason why prompt treatment can have such a dramatic effect on final recovery.

Risk factors

Risk factors for stroke involve age, sex, heredity, predisposing diseases or other medical conditions, and lifestyle choices, including:

• Age and sex. The risk of stroke increases with increasing age, doubling for each decade after age 55. Men are more likely to have a stroke than women.
• Heredity. Blacks, Asians, and Hispanics all have higher rates of stroke than do whites, related partly to higher blood pressure. People with a family history of stroke are at greater risk.
• Diseases. Stroke risk is increased for people with diabetes, heart disease (especially atrial fibrillation), high blood pressure, prior stroke, or TIA. Risk of stroke increases tenfold for someone with one or more TIAs.
• Other medical conditions. Stroke risk increases with obesity, high blood cholesterol level, or high red blood cell count.
• Lifestyle choices. Stroke risk increases with cigarette smoking (especially if combined with the use of oral contraceptives), low level of physical activity, alcohol consumption above two drinks per day, or use of cocaine or intravenous drugs.

Symptoms

Symptoms of an embolic stroke usually come on quite suddenly and are at their most intense right from the start, while symptoms of a thrombotic stroke come on more gradually. Symptoms may include:

• blurring or decreased vision in one or both eyes
• severe headache
• weakness, numbness, or paralysis of the face, arm, or leg, usually confined to one side of the body
• dizziness, loss of balance or coordination, especially when combined with other symptoms

Diagnosis

The diagnosis of stroke is begun with a careful medical history, especially concerning the onset and distribution of symptoms, presence of risk factors, and the exclusion of other possible causes. A brief neurological exam is performed to identify the degree and location of any deficits such as weakness, incoordination, or visual losses.

Once stroke is suspected, a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan is performed to distinguish a stroke caused by blood clot from one caused by hemorrhage, a critical distinction that guides therapy. Blood and urine tests are done routinely to look for possible abnormalities.

Other investigations that may be performed to guide treatment include an electrocardiogram, angiography, ultrasound, and electroencephalogram.

Treatment team

Stroke treatment involves a multidisciplinary team. Physicians are responsible for caring for the stroke survivor's general health and providing guidance aimed at preventing a second stroke. Neurologists usually lead acute-care stroke teams and direct patient care during hospitalization. The team may include a physiatrist (a specialist in rehabilitation), a rehabilitation nurse, a physical therapist, an occupational therapist, a speech-language pathologist, a social worker, a psychologist, and a vocational counselor.

Treatment

Emergency treatment

Emergency treatment of stroke from a blood clot is aimed at dissolving the clot. This "thrombolytic therapy" is currently performed most often with tissue plasminogen activator, or t-PA. This t-PA must be administered within three hours of the stroke event. Therefore, patients who awaken with stroke symptoms are ineligible for t-PA therapy, as the time of onset cannot be accurately determined. The t-PA therapy has been shown to improve recovery and decrease long-term disability in selected patients. The t-PA therapy carries a 6.4% risk of inducing a cerebral hemorrhage, and is not appropriate for patients with bleeding disorders, very high blood pressure, known aneurysms, any evidence of intracranial hemorrhage, or incidence of stroke, head trauma, or intracranial surgery within the past three months. Patients with clot-related (thrombotic or embolic) stroke who are ineligible for t-PA treatment may be treated with heparin or other blood thinners, or with aspirin or other anti-clotting agents in some cases.

Emergency treatment of hemorrhagic stroke is aimed at controlling intracranial pressure. Intravenous urea or mannitol plus hyperventilation are the most common treatments. Corticosteroids may also be used. Patients with reversible bleeding disorders such as those due to anticoagulant treatment should have these bleeding disorders reversed, if possible.

Surgery for hemorrhage due to aneurysm may be performed if the aneurysm is close enough to the cranial surface to allow access. Ruptured vessels are closed off to prevent rebleeding. For aneurysms that are difficult to reach surgically, endovascular treatment may be used. In this procedure, a catheter is guided from a larger artery up into the brain to reach the aneurysm. Small coils of wire are discharged into the aneurysm, which plug it up and block off blood flow from the main artery.

Recovery and rehabilitation

Rehabilitation refers to a comprehensive program designed to help the patient regain function as much as possible and compensate for permanent losses. Approximately 10% of stroke survivors are without any significant disability and able to function independently. Another 10% are so severely affected that they must remain institutionalized for severe disability. The remaining 80% can return home with appropriate therapy, training, support, and care services.

Rehabilitation is coordinated by a team that may include the services of a neurologist, a physiatrist, a physical therapist, an occupational therapist, a speech-language pathologist, a nutritionist, a mental health professional, and a social worker. Rehabilitation services may be provided in an acute care hospital, rehabilitation hospital, long-term care facility, outpatient clinic, or at home.

The rehabilitation program is based on the patient's individual deficits and strengths. Strokes on the left side of the brain primarily affect the right half of the body, and vice versa. In addition, in left-brain-dominant people, who constitute a significant majority of the population, left-brain strokes usually lead to speech and language deficits, while right-brain strokes may affect spatial perception. Patients with right-brain strokes may also deny their illness, neglect the affected side of their body, and behave impulsively.

Rehabilitation may be complicated by cognitive losses, including diminished ability to understand and follow directions. Poor results are more likely in patients with significant or prolonged cognitive changes, sensory losses, language deficits, or incontinence.

Preventing complications

Rehabilitation begins with prevention of stroke recurrence and other medical complications. The risk of stroke recurrence may be reduced with many of the same measures used to prevent stroke, including quitting smoking and controlling blood pressure.

One of the most common medical complications following stroke is deep venous thrombosis, in which a clot forms within a limb immobilized by paralysis. Clots that break free can often become lodged in an artery feeding the lungs. This type of pulmonary embolism is a common cause of death in the weeks following a stroke. Resuming activity within a day or two after the stroke is an important preventive measure, along with use of elastic stockings on the lower limbs. Drugs that prevent clotting may be given, including intravenous heparin and oral warfarin.

Weakness and loss of coordination of the swallowing muscles may impair swallowing (dysphagia), and allow food to enter the lower airway. This may lead to aspiration pneumonia, another common cause of death shortly after a stroke. Dysphagia may be treated with retraining exercises and temporary use of pureed foods.

Depression occurs in 30–60% of stroke patients. Antidepressants and psychotherapy may be used in combination.

Other medical complications include urinary tract infections, pressure ulcers, falls, and seizures.

Types of rehabilitative therapy

Brain tissue that dies in a stroke cannot regenerate. In some cases, other brain regions may perform the functions of that tissue after a training period. In other cases, compensatory actions may be developed to replace lost abilities.

Physical therapy is used to maintain and restore range of motion and strength in affected limbs, and to maximize mobility in walking, wheelchair use, and transferring (from wheelchair to toilet or from standing to sitting, for instance). The physical therapist advises on mobility aids such as wheelchairs, braces, and canes. In the recovery period, a stroke patient may develop muscle spasticity and contractures, or abnormal contractions. Contractures may be treated with a combination of stretching and splinting.

Occupational therapy improves self-care skills such as feeding, bathing, and dressing, and helps develop effective compensatory strategies and devices for activities of daily living. A speech-language pathologist focuses on communication and swallowing skills. When dysphagia is a problem, a nutritionist can advise alternative meals that provide adequate nutrition.

Mental health professionals may be involved in the treatment of depression or loss of thinking (cognitive) skills. A social worker may help coordinate services and ease the transition out of the hospital back into the home. Both social workers and mental health professionals may help counsel the patient and family during the difficult rehabilitation period. Caring for a person affected with stroke requires learning a new set of skills and adapting to new demands and limitations. Home caregivers may develop stress, anxiety, and depression. Caring for the care-giver is an important part of the overall stroke treatment program.

Support groups can provide an important source of information, advice, and comfort for stroke patients and for caregivers. Joining a support group can be one of the most important steps in the rehabilitation process.

Clinical trials

As of mid-2004, there were numerous open clinical trials for stroke, including:

• "Adjunctive Drug Treatment for Ischemic Stroke Patients," "E-Selectin Nasal Spray to Prevent Stroke Recurrence," "Improving Motor Learning in Stroke Patients," "Aspirin or Warfarin to Prevent Stroke," "Hand Exercise and Upper Arm Anesthesia to Improvements Hand Function in Chronic Stroke Patients," "Preliminary Study of Transcranial Magnetic Stimulation for Stroke Rehabilitation," and "Using fMRI to Understand the Roles of Brain Areas for Fine Hand Movements" are all sponsored by the National Institute of Neurological Disorders and Stroke.
• "Preventing Post-Stroke Depression" is sponsored by the National Institute of Mental Health (NIMH).
• "Walking Therapy in Hemiparetic Stroke Patients Using Robotic-Assisted Treadmill Training" is sponsored by the United States Department of Education.
• "Brain Processing of Language Meanings" is sponsored by Warren G. Magnuson Clinical Center.

Updated information on these and other ongoing trials for the study and treatment of stroke can be found at the National Institutes of Health Web site for clinical trials at .

Prognosis

Stroke is fatal for about 27% of white males, 52% of black males, 23% of white females, and 40% of black females. Stroke survivors may be left with significant deficits. Emergency treatment and comprehensive rehabilitation can significantly improve both survival and recovery.

Prevention

Damage from stroke may be significantly reduced through emergency treatment. Knowing the symptoms of stroke is as important as knowing those of a heart attack. Patients with stroke symptoms should seek emergency treatment without delay, which may mean dialing 911 rather than their family physician.

The risk of stroke can be reduced through lifestyle changes, including:

• stopping smoking
• controlling blood pressure
• getting regular exercise
• keeping weight down
• avoiding excessive alcohol consumption
• getting regular checkups and following the doctor's advice regarding diet and medicines

Treatment of atrial fibrillation may significantly reduce the risk of stroke. Preventive anticoagulant therapy may benefit those with untreated atrial fibrillation. Warfarin (Coumadin) has proven to be more effective than aspirin for those with higher risk.

Screening for aneurysms may be an effective preventive measure in those with a family history of aneurysms or autosomal polycystic kidney disease, which tends to be associated with aneurysms.

Resources

BOOKS

Caplan, L. R., M. L. Dyken, and J. D. Easton. American Heart Association Family Guide to Stroke Treatment, Recovery, and Prevention. New York: Times Books, 1996.

Warlow, C. P., et al. Stroke: A Practical Guide to Management. Boston: Blackwell Science, 1996.

Weiner F., M. H. M. Lee, and H. Bell. Recovering at Home After a Stroke: A Practical Guide for You and Your Family. Los Angeles: The Body Press/Perigee Books, 1994.

PERIODICALS

Selman, W. R., R. Tarr, and D. M. D. Landis. "Brain Attack: Emergency Treatment of Ischemic Stroke." American Family Physician 55 (June 1997): 2655–2662.

Wolf, P. A., and D. E. Singer. "Preventing Stroke in Atrial Fibrillation." American Family Physician (December 1997).

ORGANIZATIONS

National Stroke Association. 9707 E. Easter Lane, Englewood, Co. 80112. (800) 787-6537. (June 3, 2004). http://www.stroke.org.

American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300. (June 3, 2004). http://www.americanheart.org.

Richard Robinson

(1) In printing, the weight, or thickness, of a character. For example, in the LaserJet, one of the specifications of the font description is the stroke weight from lightest to boldest. See stroke weight.

(2) In computer graphics, a pen or brush stroke. The stroke function lets you set the width of the line being drawn.

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Apoplexy or stroke has been recognized at least since the beginning of Western medicine, in ancient Greece. Stroke arises from injury to the brain caused by interruption of the blood supply, rather like a heart attack: in fact stroke is now sometimes called a ‘brain attack’. Over 250 000 people suffer some type of stroke in the UK each year. Stroke now is the third leading cause of death and the most common cause of adult disability.

The most typical manifestations include sudden weakness of the face, arm, or leg, and altered sensation or numbness, on the side of the body opposite the stroke. Language expression and comprehension can be impaired, usually for strokes in the left cerebral hemisphere. A stroke in the occipital lobe, at the back of the hemisphere, can cause blindness in the opposite half of the visual field. Sometimes a stroke in the parietal lobe of the right hemisphere renders the patient unable to attend to the left hand side of objects or even without awareness of the left side of their own body (the so-called neglect syndrome). Most bizarre of all, damage to the right hemisphere can produce anosagnosia — denial by the patient of any deficit at all, despite virtual paralysis of the left arm and leg.

The brain — especially the cerebral cortex, a frequent target of strokes — is divided into distinct regions, functionally specialized for one sense or another, for the control of movement, for aspects of language, etc. The sensory, motor, linguistic, and cognitive deficits caused by small strokes can therefore be extraordinarily specific, and their interpretation by neuropsychologists has been a major source of evidence about the organization of the human brain. But major strokes can have devastating effects, sometimes eliminating consciousness completely, or, perhaps even worse, leaving a conscious mind in a useless body. The French writer Jean-Dominique Bauby gives a unique view of this state in his autobiography — paralysed except for the capacity to blink an eye, he described himself as a ‘butterfly’ trapped inside a ‘diving bell’.

In 1761, Battista Morgagni, Professor of Anatomy in Padua, first clearly attributed strokes to limitation of blood flow to the brain. In 85% of cases this comes from blockage of a blood vessel giving a so-called ischaemic stroke. Most of the remaining 15% are due to sudden bleeding into the substance of the brain to create a haemorrhagic stroke. A small percentage are due to rupture of an artery in the surface of the brain — a subarachnoid haemorrhage.

The brain is metabolically highly active. Although it accounts for only about 2% of the body weight, it uses 20% of the total oxygen intake and has a high demand for the blood sugar, glucose. At least 15% of the blood output from the heart is needed to supply this amount of oxygen and glucose. If this blood flow is interrupted, even for minutes, then brain cells die. The pattern of clinical deficits after strokes (other than subarachnoid haemorrhage) is determined by the particular blood vessel that is primarily affected. Interruption of flow in the left middle cerebral artery, for example, typically leads to specific impairments of language or calculation, while occlusion of the right middle cerebral artery may disturb visual-spatial skills. Subarachnoid haemorrhages lead to changes in pressure on the brain and chemical effects that cause more general deficits.

The most common cause of ischaemic strokes is blocking of a vessel by a so-called embolus, which forms on a pathologically abnormal wall of a larger vessel and then detaches and circulates in the blood. The wall of the larger vessel, particularly in areas of high-flow turbulence and around major bifurcations (e.g. the point at which the internal carotid artery branches off from the aorta), may become thickened and irregular, and calcified atherosclerotic plaques may form. Rupture of these plaques can form a blood clot, fragments of which can be carried along the course of flowing blood to block smaller vessels. Alternatively, platelets that aggregate on the abnormal surface of a plaque, or fragments of the plaque, can themselves act as emboli. Emboli also can be formed in the heart, or, more rarely, can come from elsewhere in the body.

(a) CT brain scan within 24 hours of an ischaemic stroke due to blockage in large middle cerebral artery (arrow). (b) The next day the CT scan shows a transformed area (arrow). Without knowledge of (a) it would be very difficult to distinguish this area of change from intracerebral haemorhage. (Donaghy, T. (2001). Brain's diseases of the nervous system, 11th edn, Oxford University Press, Oxford.)


The risk of stroke is determined by both genetic and environmental influences. A number of specific risk factors include: a family history of stroke in first-degree relatives; older age; male sex; hypertension; smoking; diabetes; and heart disease.

Control of risk factors (e.g. giving up smoking, control of hypertension or diabetes, treatment of heart disease) can reduce the risk of stroke in affected individuals. The importance of hypertension has been recognized in a practical way since the time of Galen (c. ad 130-210), who advocated treatment of apoplexy with vigorous blood-letting.

Perhaps half or more of strokes are preceded by neurological symptoms (such as difficulty with speech or with movement of one hand) that last less than 12 hours and reverse completely. However, the risk of a full-blown stroke following these transient ischaemic attacks (TIAs) is similar to the risk that a stroke leaving persistent deficits will be followed by another (approximately 12% overall risk over 12 months). The precise risks vary substantially, however, depending on the underlying cause and the particular blood vessel involved.

Acute treatment of smaller ischaemic strokes is generally based on use of drugs that limit platelet aggregation, such as aspirin. Patients with occlusion of relatively large vessels, who reach medical care within the first few hours after the onset of deficits, may benefit from infusion of thrombolytic agents (clot-busters) such as tissue plasminogen activator (tPA) that can dissolve emboli and restore blood flow in the ischaemic area. This may benefit particularly the tissue at the outside of the core of the damage, in the so-called ischaemic penumbra, where the function of brain tissue is not irreversibly impaired.

Patients who survive their strokes without massive neurological deficits always show significant functional improvement. This occurs most rapidly over the first month after the stroke, but can continue for two years or more. The degree of recovery depends not only on the size of a stroke but also on its location. For example, small ischaemic strokes in the basal ganglia — nuclei deep in the cerebral hemispheres, involved in the control of movement — have a much better prognosis than strokes in the posterior limb of the internal capsule (see brain), which contains major nerve fibres running between the cerebral cortex and the rest of the brain.

Recovery is often complicated by less well-understood consequences of stroke, which illustrate the complex interconnectedness of brain functions. Alfred Brodal, the famous Danish neuroanatomist, observed in 1973 after his own small, ‘pure motor’ stroke that, in addition to difficulties moving one half of his body, he suffered from a ‘loss of powers of concentration, reduced short-term memory, increased fatigue, reduced initiative, [and] incontinence of movements of emotional expression’. Depression can also be a major problem. In part this is a consequence of the patient's perception of the new disability. Sir Peter Medawar, Nobel Laureate in Medicine, describes this well in personal reflections on his own stroke entitled Memoirs of a Thinking Radish (1986). Strokes can have direct effects on the balance of neurotransmitters in the brain that are responsible for mood.

Current experimental strategies for treatment in stroke are focusing simultaneously on several areas: safer and more effective ways of delivering thrombolytic therapy to patients, with particular attention to the possibility of rapid, on-the-spot treatment; neuroprotective agents, designed to guard the surrounding area of brain from the effects of neurotransmitters released by dying neurons following the initial damage of the stroke; and other experimental drugs, directed at limiting damage from the breakdown of nerve cell membranes and highly reactive oxygen radicals that are generated in the damaged tissue.

An intriguing possibility is that cells derived from bone marrow (stem cells) could be implanted surgically into areas of brain damaged by stroke, where they may be able to differentiate into new neurons that could take over functions of those that have been damaged.

— Paul M. Matthews

Bibliography

• Bauby, J.-D. (1998). The diving-bell and the butterfly. Fourth Estate, London.
• Kapur, N. (1997). Injured brains of medical minds. Oxford University Press.
• Porter, R. (1999). The greatest benefit to mankind. Fontain Press, London

See also apoplexy; brain; language and the brain; paralysis.

Also known as cerebrovascular accident (CVA); damage to brain tissue by hypoxia due to blockage of a blood vessel as a result of thrombosis, atherosclerosis, or haemorrhage. The severity and nature of the effects of the stroke depend on the region of the brain affected and the extent of damage. Hypertension and hypercholesterolaemia are major risk factors.

An interruption of the blood supply to the brain. A blood clot, a head injury, or a burst blood vessel in the brain (an aneurysm) can cause strokes. The main risk factors associated with strokes are high blood pressure, heart diseases, diabetes, smoking, obesity, and physical inactivity.

A stroke results in a portion of the brain being deprived of oxygen often leading to some type of paralysis, but small strokes may occur without symptoms. Large strokes can result in severe paralysis or death. Regular exercise and a healthy, balanced diet lower blood pressure and cholesterol levels, and so can reduce the risk of a stroke.

n

Definition: accomplishment
Antonyms: failure, loss

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Common name for the slant (‘/’, ASCII 0101111) character. See ASCII for other synonyms.

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n

1. a single, unbroken movement made by an instrument or the mandible. 2. common term for accident, cerebrovascular.

Definition

Stroke is the common name for the injury to the brain that occurs when the flow of blood to brain tissue is interrupted by a clogged or burst artery. Arterial blood carries oxygen and nutrition to the cells of the body. When arteries are unable to carry out this function due to rupture, constriction, or obstruction, the cells nourished by these arteries die. The medical term for stroke is the acronym CVA, or cerebral vascular accident. It is estimated that four of every five families in the United States will be affected by stroke in their lifetime, and it is the top cause of adult disability worldwide. Stroke is ranked third in the leading causes of death in the United States, has left three million Americans permanently disabled, and costs the United States 30 billion dollars each year in terms of health care costs and lost productivity.

The most common type of stroke is classified as ischemic, or occurring because the blood supply to a portion of the brain has been cut off. Ischemic strokes account for approximately 80% of all strokes, and can be further broken down into two subtypes: thrombotic, also called cerebral thrombosis; and embolic, termed cerebral embolism.

Thrombotic strokes are by far the more prevalent, and can be seen in nearly all aging populations worldwide. As people grow older, atherosclerosis, or hardening of the arteries, occurs. This results in a buildup of a waxy cholesterol-laden substance in the arteries, which eventually narrows the interior space, or lumen, of the artery. This arterial narrowing occurs in all parts of the body, including the brain. As the process continues, the occlusion, or shutting off of the artery, eventually becomes complete, so that no blood supply can pass through. Usually the presentation of the symptoms of a thrombotic stroke are much more gradual and less dramatic than that of other strokes due to the slow ongoing process that produces it. Transient ischemic attacks, or TIAs, are one form of thrombotic stroke, and usually the least serious. TIAs represent the blockage of a very small artery or arteriole, or the intermittent or temporary obstruction of a larger artery. This blockage affects only a small portion of brain tissue and does not leave noticeable permanent ill effects. These transient ischemic attacks last only a matter of minutes, but are a forewarning that part of the brain is not receiving its necessary supply of blood, and thus oxygen and nutrition. Thrombotic strokes account for 40-50% of all strokes.

Embolic strokes are more acute and rapid in onset. They take place when the heart's rhythm is changed for a number of different reasons, and blood clot formation occurs. This blood clot can move through the circulatory system until it blocks a blood vessel and stops the blood supply to cells in a specific portion of the body. If it occludes an artery that nourishes heart muscle, it causes myocardial infarction, or heart attack. If it blocks off a vessel that feeds brain tissue, it is termed an embolic stroke. Embolisms account for 25-30% percent of all strokes. Normally these blockages occur in the brain itself when arteries directly feeding portions of brain tissue are blocked by a clot. But occasionally the obstruction is found in the arteries of the neck, especially the carotid artery.

Approximately 20% of cerebral vascular accidents are termed hemorrhagic strokes. Hemorrhagic strokes occur when an artery to the brain has a weakness and balloons outward, producing what is called an aneurysm. Such aneurysms often rupture due to this inflation and thinning of the arterial wall, causing a hemorrhage in the affected portion of the brain.

Both ischemic and hemorrhagic strokes display similar symptoms, depending on which portion of the brain is cut off from its supply of oxygen and nourishment. The brain is divided into left and right hemispheres. These hemispheres are responsible for bodily movement on the opposite side of the body from the brain hemisphere. For example, the left hemisphere of the brain is responsible for both motor control and sensory discrimination for the right side of the body, just as the right hemisphere is responsible for left body movements and feeling. Deeper brain tissue in the left hemisphere of the brain directs muscle tone and coordination for both the right arm and leg. As the communication and speech centers for the brain are also located in the left hemisphere of the brain, interruption of blood supply to that area can also typically affect the person's ability to speak.

Description

Strokes are always considered a medical emergency, and every minute is important in initiating treatment. With the possible exception of transient ischemic attacks, all other types of stroke are life-threatening events. Stroke is a leading cause of death in all nations of the Western world and the more affluent Asian countries. One-quarter of all strokes are fatal. Cerebral vascular accidents are typically a condition of the elderly, and more often happen to men than women. In the United States, strokes occur in roughly one of every 500 people, and the likelihood of becoming a stroke victim rises sharply as a person ages. The incidence of strokes among people ages 30-60 years is less than 1%. This figure triples by the age of 80 years.

Causes & Symptoms

Along with the typical risk factors for heart disease, the most common risk factor for thrombotic stroke is age. Some buildup of material along the inner lumen of the artery, or atherosclerosis, is a normal part of growing older. Hypertension, or high blood pressure, can result from this buildup, as the heart attempts to pump blood through these narrowed arteries. High blood pressure is one of the foremost causes of stroke. Aside from aging and hypertension, heart disease, obesity, diabetes, smoking, oral contraceptives in women, polycythemia, and a condition called sleep apnea are all risk factors for stroke, as is a diet high in cholesterol or fatty foods.

The risk factors for hemorrhagic stroke are those that can weaken arteries supplying blood to the brain. They include high blood pressure, which can over a period of time cause the ballooning of arteries known as aneurysm, and hereditary malformations that produce defective and weakened veins and arteries. Substance abuse also is a major cause. It has been demonstrated for years that cocaine and stimulants such as amphetamine drugs are culprits, and chronic alcoholism can cause a weakening of blood vessels that also can result in hemorrhagic stroke.

Exactly what triggers the actual ischemic stroke event continues to puzzle clinicians. Researchers refer to these triggers as "short-term risk" vs. "long-term risk" factors. If researchers can help identify the triggers for stroke in those with high risk factors, they might be able to help prevent the stroke from occurring. One 2002 report found that abrupt changes in body position caused by sudden loud noises or other unexpected events might trigger a stroke. These events occurred during a two-hour period before the stroke. As noted previously, the symptoms of stroke observed depend upon the part of the brain that is affected, and how large a portion of brain tissue has been damaged by the CVA. Unconsciousness and even seizures can be initial components of a stroke. Other effects materialize over a time period ranging from minutes to hours, and even, in some rare instances, over several days. Headache (often described as "the worst headache I've ever had" in hemorrhagic stroke); mental confusion; vertigo; vision problems, aphasia, or difficulty speaking and communicating, including slurring of words are major symptoms. Hemiplegia, or weakness or paralysis of one side of the body, is a symptom that is frequently seen. This one-sided weakness is often first noticed in the person's face. Stroke victims often have facial drooping, or slackness of the facial muscles on the affected side, as well as difficulty swallowing. The severity of these symptoms will depend upon the amount of brain tissue that has died and its location in the brain.

Computed tomography (CT) brain scans, angiography, lumbar puncture, and magnetic resonance imaging (MRI) are all used to rule out any other possible causes of the symptoms seen. Other possible causes of these symptoms could be brain tumor, brain abscess, subdural hematoma, encephalitis, and meningitis.

Treatment

There are many applications of alternative and complementary medicine in the treatment and prevention of stroke. Alternative therapies are also used in rehabilitation of stroke victims. Acupuncture and acupressure are commonly used for stroke patients, as is massage. Movement and meditation programs such as t'ai chi are also helpful. Herbs with antioxidant properties may be prescribed by a practitioner. Many therapies aid in blood pressure control, including meditation, guided imagery, biofeedback and t'ai chi.

Allopathic Treatment

Much of the needed care immediately following a stroke will be to prevent damage beyond that which has already occurred. Paralysis requires prevention of contractures or tightening up of paralyzed limbs. This is done through physiotherapy, and may include the use of supportive braces for arms or hands, footboards or wearing sneakers when in bed to prevent foot drop. The severely ill stroke patient will need to be repositioned frequently to prevent complications such as pneumonia and venous or pulmonary embolism.

Because of difficulty in swallowing, the person who has suffered a stroke may need a temporary or permanent feeding tube inserted into the stomach to ensure adequate nutrition. Such tubes can be placed through the nose, into the esophagus, and into the stomach, or gastrically, with a wider-lumen tube surgically implanted into the stomach.

A severe stroke that results in coma or unconsciousness will require medical monitoring and support, including oxygen and even possibly intubation to assure an adequate airway and facilitate breathing. Provision of fluids that the person may not be able to take by mouth due to swallowing difficulties will be necessary, as will possibly the administration of such blood-thinning or clot-dissolving medications as Coumadin or heparin. A five-year clinical trial completed in 1995 and reported by the New England Journal of Medicine showed that stroke patients treated with t-PA, a clot-dissolving medication, within three hours of the stroke were one-third more likely to be left with no permanent residual difficulty. The trauma of the brain caused by stroke may result in edema, or swelling, which may have to be reduced by giving the patient diuretic or steroid medications. Sometimes surgical removal of a clot obstructing an artery is necessary. Hemorrhagic stroke can cause a buildup of pressure on the brain that must be relieved as quickly as possible to prevent further brain damage. In extreme cases, this may require incision through the skull to relieve that pressure.

Expected Results

Studies reported by the National Institute of Neurological Disorders and Stroke report that 25% of people who suffer a stroke recover completely and 20% die within three months after the stroke. Of the remaining 55% percent, 5% will require long-term (nursing home) care, and for the rest — roughly half of all stroke patients — rehabilitative and restorative services will be necessary to regain as much of their former capabilities as possible. It has been estimated that the most common irreversible damage from stroke is the loss of intellectual functions.

Prevention

Control of blood pressure is the single most important factor in preventing stroke. People should have their blood pressure checked regularly, and if consistently elevated, (diastolic, or lower blood pressure beat above 90 to 100, systolic or top beat above 140 to 150), a physician should be consulted.

The American Heart Association recommends that cigarette smokers break the habit to reduce stroke risk. Current cigarette use can increase risk of cerebral infarction to nearly double, and smoking is associated with other risk factors of stroke. The AHA also recommends that those at risk for stroke avoid secondhand tobacco smoke if possible.

Diet, including reduction of sodium (salt) intake, exercise and weight loss, if overweight, are all non-drug treatments for lowering blood pressure. Other natural remedies include eating artichokes, which lowers the fat content of the blood; garlic, now believed to lower cholesterol and blood pressure as well as to reduce the clotting ability of the blood; and ginkgo, which improves circulation and strengthens arteries and veins. The use of folic acid, lecithin, vitamins B 6 and B₁₂, vitamins C and E are all recommended as supportive measures in reducing blood pressure. Two new Harvard studies found that eating a diet high in fruits and vegetables (particularly leafy green vegetables and cruciferous ones like broccoli, cauliflower, and cabbage) can reduce the risk of ischemic stroke. When fruits and vegetables were not only added to the diet, but replaced meat and trans fats, they further reduced stroke risk.

Avoiding substances that can cause stroke is another preventive measure. A 2002 report revealed that the popular herbal supplement ephedrine can cause stroke, heart attack, and sudden death.

Multiple studies have found that aspirin acts as a blood-thinning or clot-reducing medication when taken in small doses. One baby aspirin tablet per day provides this anticoagulant protection.

If necessary, a physician may also order medication to lower blood pressure. These medications include the following categories of drugs:

• Beta blockers reduce the force and speed of the heartbeat.
• Vasodilators dilate the blood vessels.
• Diuretics reduce the total volume of circulating blood and thus the heart's work by removing fluid from the body.
• Lipid-lowering drugs increase the loss of cholesterol from the body or prevent the conversion of fatty acids to cholesterol. This lowers fat levels in the blood stream.

A preliminary report out of France in 2002 stated that getting a flu shot might reduce risk of stroke. Previous research has also suggested that flu shots might stimulate a response in the immune system that helps reduce inflammation throughout the body. If true, those most likely to benefit would be people age 75 and older.

Resources

Books

Clayman, Charles B., MD. The American Medical Association Home Medical Encyclopedia. New York: Random House, 1989.

Landis, Robyn, and Karta Purkh Singh Khalsa. Herbal Defense: Positioning Yourself to Triumph Over Illness and Aging. New York: Warner Books, 1997.

Sammons, James H., MD, John T. Baker, MD, Frank D. Campion, Heidi Hough, James Ferris, Brenda A. Clark. The American Medical Association Guide to Prescription and Over-the-Counter Drugs. New York: Random House, 1988.

Thomas, Clayton L. Taber's Cyclopedic Medical Dictionary. F.A. Davis Co., 1998.

Periodicals

"Abrupt Changes in Body Position Can Trigger Stroke." Heart Disease Weekly (March 24, 2002):15.

"Flu Shots May Prevent Strokes." Medical Update (February 2002):5.

Hall, Zach W., Ph.D. New England Journal of Medicine (December 14, 1995).

Samenuk, David. "Adverse Cardiovascular Events Temporarily Associated with Ma Huang, an Herbal Source of Ephedrine." JAMA, Journal of the American Medical Association (March 27, 2002):1506.

"Strategies Identified to Prevent Primary Stroke." Clinician Reviews (March 2002):89.

"Vegetables and Fruits Cut Stroke Risk." Health Science (Winter 2002):7.

Organizations

National Institute of Neurological Disorders and Stroke. National Institutes of Health, Building 31, Room 8A-16, P.O. Box 5801, Bethesda, MD 20824. (301) 496-5751.

National Stroke Association. 1-800-STROKES. http://www.stroke.org.

Other

Dr. Rappa. "What Is a Stroke?" http://www.medhealthsolution.com.

[Article by: Joan Schonbeck; Teresa G. Odle]

Definition

A stroke, also called a cerebral infarction, is a life-threatening condition marked by a sudden disruption in the blood supply to the brain.

Description

A disruption in the blood supply to the brain starves the brain of oxygen-rich blood and causes the nerve cells in that area to become damaged and die within minutes. The body parts controlled by those damaged brain cells lose their ability to function.

Depending on the area of the brain that is affected, a stroke can alter many aspects of a child's functioning such as speech, movement, behavior and learning. A stroke also may cause weakness or paralysis on one side of the body. The loss of function may be mild or severe, temporary or permanent.

If medical treatment begins within hours after symptoms are recognized, brain damage can be limited and the risk of permanent medical effects can be decreased.

Types of Stroke

An ischemic stroke—the most common form of stroke in children under age 15—is caused by a blocked or narrowed artery. In children, blockages may be caused by a blood clot, injury to the artery, or rarely in children, atherosclerosis (build-up of fatty deposits on the blood vessel walls). A cerebral thrombosis is a blood clot that develops at the clogged part of the blood vessel. A cerebral embolism is a blood clot that travels to the clogged blood vessel from another location in the circulatory system.

A hemorrhagic stroke—the more common form of stroke in infants and children under age two—occurs when a weakened blood vessel leaks or bursts, causing bleeding in the brain tissue or near the surface of the brain.

Two types of weakened blood vessels usually cause hemorrhagic stroke, including:

• aneurysm: ballooning of a weakened area of a blood vessel
• arteriovenous malformations: cluster of abnormal blood vessels

A transient ischemic attack (TIA), also called a "mini stroke," is characterized by a short-term blood vessel obstruction or clot that tends to resolve itself quickly, usually within 10–20 minutes, or up to 24 hours. A TIA usually does not require intervention. However, a TIA is a strong indicator of an ischemic stroke and should be evaluated in the same way as a stroke to prevent a more serious attack.

In children, strokes can be categorized as:

• prenatal stroke: occurring before birth
• neonatal or perinatal stroke: occurring in infants less than 30 days old
• pediatric or childhood stroke: occurring in children aged 15 and under

Demographics

Childhood stroke is relatively rare, occurring in about two to three of every 100,000 children aged one to 14 per year. In comparison, stroke occurs in about 100 of every 100,000 adults per year. The rate of ischemic stroke and hemorrhagic stroke is similar among children aged one to 14.

Stroke occurs more frequently in children under age two, and peaks in the perinatal period. In the National Hospital Discharge Survey from 1980-1998, the rate of stroke for infants less than 30 days old (per 100,000 live births per year) was 26.4, with rates of 6.7 for hemorrhagic stroke and 17.8 for ischemic stroke.

More fatal strokes occur in African-American children than white children, mirroring the racial differences of stroke in adults. Compared to the stroke risk of white children, African-American children have an increased relative risk of 2.12, Hispanics a decreased relative risk of 0.76 and Asians have a similar risk. Boys have a 1.28-fold higher risk of stroke than girls and have a higher case-fatality rate for ischemic stroke than girls. The increased risk among African Americans is not explained by the presence of sickle cell disease, nor is the excess risk among boys explained by trauma.

Research conducted by the National Institute of Neurological Diseases and Stroke (NINDS) indicates a "stroke belt," or geographical area where fatal strokes are more predominant. This stroke belt includes Alabama, Arkansas, Georgia, Indiana, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, and Virginia. Researchers examined death certificates over a 19-year period and found a 21 percent higher risk of death from stroke in people under age 20 in the stroke belt states had compared with the same age group in other states. During the same period, people over age 25 in the stroke belt region had a 20 percent higher risk of death from stroke. Because the overall rate of stroke in children is low, researchers warn parents in these states not to be too alarmed. However, the findings indicate further investigation is needed.

Causes and Symptoms

Causes

The cause of childhood stroke is unknown in one-third of cases, and an underlying medical condition or multiple conditions appear to contribute to over half of the cases. The most common causes of stroke are congenital (present at birth) and acquired heart diseases, and sickle cell anemia.

About 10–15 percent of children with sickle cell disease suffer a stroke, usually ischemic stroke. Sickle cell disease is a blood disorder in which the blood cells cannot carry oxygen to the brain because the blood vessels to the brain are either narrowed or closed.

One rare cause of stroke is an extreme case of the chickenpox virus, which causes a narrowing of blood vessels in the head for some children.

RISK FACTORS. Although obesity, high cholesterol, high blood pressure, atherosclerosis, and smoking are common stroke risk factors in adults, they rarely contribute to stroke risk in children. Risk factors for childhood stroke include a family history of stroke, cardiovascular disease or diabetes, as well as the presence of the conditions listed below.

Some of the more common congenital heart diseases that increase the risk of childhood stroke include:

• aortic and mitral valve stenosis
• atrial septal defect
• patent ductus arteriosus (PDA)
• patent foramen ovale
• inherited blood clotting disorders
• ventricular septal defect
• hypercoagulable states

Some of the acquired heart conditions that increase the risk of childhood stroke include:

• bacterial meningitis
• endocarditis
• arrhythmia and atrial fibrillation
• artificial heart valve
• myocarditis
• cardiomyopathy
• rheumatic heart disease
• embolism
• anoxia
• antiphospholipid antibody syndrome
• encephalitis
• blood vessel disease
• certain blood disorders, such as hemophilia
• inborn errors of metabolism
• illicit drug use
• teenage pregnancy
• teen use of oral contraceptives (birth control pills)

Possible traumas that increase the risk of childhood stroke include birth injury or trauma, child abuse, or other injury or trauma.

Because of the wide range of secondary conditions that contribute to stroke, it is difficult for researchers to assess the relative contribution of each risk factor to the problem of cerebrovascular disease as a whole, according to the Child Neurology Society Ad Hoc Committee on Stroke in Children. In addition, this variability also hinders clinical research.

Symptoms

In infants and very young children, stroke symptoms are sudden and include:

• seizures
• coma
• paralysis on one side of the body
• nausea or vomiting

In older children, stroke symptoms are sudden and include:

• numbness or weakness of the face, arm, or leg, especially on one side of the body
• confusion or difficulty speaking or understanding speech
• vision difficulties, often in one eye
• hearing problems, often in one ear
• difficulty walking, dizziness or loss of balance or coordination
• severe headache
• difficulty swallowing
• nausea or vomiting
• painful or stiff neck

Other stroke signs and symptoms include:

• sudden severe headache with unknown cause
• sudden nausea or vomiting
• warm, flushed, clammy skin
• slow, full pulse
• appearance of unequal pupils
• facial "droop" on one side
• salivary drool
• urinary incontinence

If the child seems to recover quickly from these stroke symptoms, a TIA may have occurred. All neurological symptoms should serve as a stroke "warning sign" and could indicate a pending, more serious attack. The child should receive prompt evaluation so necessary preventive therapies can be initiated.

WHEN TO CALL THE DOCTOR. If a child has any of the symptoms listed above, the parent or caregiver should immediately dial 9-1-1 to seek emergency care. It is important not to wait to see if symptoms subside; a stroke is a medical emergency. Until the paramedics arrive, the parent or caregiver should follow these first aid guidelines:

• Make sure the child is in a comfortable posture, lying on his or her side, so the airway does not become obstructed by drool or mucus.
• Talk reassuringly to the child, even if he or she is unconscious.
• Do not leave the child alone—constantly observe the child.
• Cover the child with a blanket or remove clothing as needed to maintain the child's normal body temperature.
• Do not give the child any medication, including aspirin; medication will be given later as needed.

Diagnosis

In most children, the diagnosis of stroke is delayed by more than 24 hours from the onset of symptoms. This delay is thought to occur because there is a lack of general awareness by physicians and families of cerebrovascular disorders in children. However, early recognition and treatment of a stroke could improve management, reduce the risk of brain damage and permanent disability, help prevent a recurrence, and initiate a proper treatment and rehabilitation program to maximize functional recovery.

The diagnosis of pediatric stroke generally occurs in the emergency room and includes:

• personal and family medical history
• review of current medications
• evaluation of other health problems
• physical examination
• brief neurological exam
• diagnostic tests

The medical history helps the physician evaluate the presence of other conditions or disorders that might have caused the stroke. The child's family medical history is evaluated to determine if there is a history of cardiovascular or neurological diseases that might increase the risk of blood clots.

The brief neurological exam includes a review of the patient's mental status, motor and sensory system, deep tendon reflexes, coordination, and walking pattern (gait). The cranial nerve function also will be evaluated and includes a review of the patient's visual function and eye movement, strength of facial muscles, the gag reflex, tongue and lip movements, ability to smell and taste, hearing, and sensation and movement of the face, head, and neck.

Questions about the child's condition may include:

• What symptoms occurred?
• When were the symptoms first noticed?
• How long did the symptoms last?
• What functions were affected?

During the physical exam, the child's pulse, blood pressure, and height and weight are checked and recorded.

Diagnostic tests include:

• Blood tests: Test used to detect the presence of any chemical abnormalities, infection, or blood clotting that may have caused the stroke.
• Magnetic resonance imaging (MRI) scan: An imaging technique that provides a detailed picture of the brain without the use of x rays. MRI uses a large magnet, radio waves and a computer to produce these images.
• Computed tomography (CT) scan: An imaging technique that shows the blood vessels in the brain. A CT scan is used to identify the area of the brain affected and to detect signs of swelling.
• Chest x ray: X rays are used to detect an enlarged heart, vascular abnormalities, or lung problems.
• Angiogram: An invasive imaging technique used to examine the blood vessels in the brain. An angiogram is only performed if the CT or MRI scans do not show conclusive results.
• Echocardiogram (echo): A graphic outline of the heart's movement, valves and chambers, used to determine if the stroke was caused by a blood clot traveling from the heart to the brain. Echo is often combined with Doppler ultrasound and color Doppler. During the echo, an ultrasound transducer (hand-held wand placed on the skin of the chest) emits high-frequency sound waves to produce pictures of the heart's valves and chambers.

MRI is more sensitive than CT scanning for the diagnosis of an ischemic stroke within 24 hours. However, the two tests are comparable when used to evaluate the effects of a hemorrhagic stroke.

In rare cases or when carotid artery disease is suspected, additional tests may include a carotid ultrasound or cerebral or carotid angiogram. Other tests to diagnose stroke may include a transcranial Doppler ultrasound and neurosonogram. In a transcranial Doppler ultrasound, sound waves are used to measure blood flow in the vessels of the brain. In a neurosonogram, ultra high frequency sound waves are used to analyze blood flow and possible blockages in the blood vessels in or leading to the brain.

If a pediatric stroke is diagnosed, additional tests may be performed to assess the overall function

• Electroencephalogram (EEG): Electrodes (small, sticky metal patches attached to the scalp) are connected by wires (leads) to an electroencephalograph machine to chart the brain's continuous electrical activity.
• Evoked potentials study: Wires attached to the scalp, neck, and limbs are connected to a computer to measure the electrical activity in certain areas of the brain and spinal cord when specific sensory nerve pathways are stimulated. The brain's electrical response to visual, auditory, and sensual stimulation is recorded.

Treatment

Initial treatment depends on the type of stroke. For an ischemic stroke, initial emergent treatment focuses on restoring blood flow to the brain. For a hemorrhagic stroke, the goal of initial treatment is to control the bleeding. Children with a hemorrhagic stroke may be transferred to a center with neurosurgical facilities so the proper treatment, such as decompression or hydrocephalus drainage, can be provided by skilled specialists.

Emergency-room treatment may include: oxygen to ensure the brain is getting the maximum amount, control of body temperature, assessment and treatment of breathing difficulties, intravenous fluids to prevent or treat dehydration, and medications to control blood pressure and prevent blood clotting. Blood transfusions may be used to treat children with sickle cell disease.

Treatment Team

Treatment should be provided by a pediatric neurologist and a multi-disciplinary team of specialists that may include a physical therapist, occupational therapist, speech therapist, social worker, and other specialists as needed to meet the child's individual needs.

Medications

Adult stroke patients who receive treatment within three hours after the onset of stroke symptoms may receive a "clot-busting" medication called t-PA. However, the diagnosis of stroke is rarely made within three hours, so the use of this drug in children is uncommon.

Anticoagulant medications, including heparin or warfarin and low-dose aspirin, may be used to reduce the risk of blood clot formation. Although experience with these medications in children suggests they are safe, their use in children remains controversial because of the risk of Reye's syndrome. Sometimes the potential benefits of these medications outweigh the small risk of side effects. Researchers agree that further studies are needed to determine the proper dosage and effectiveness of aspirin and other anticoagulant medications for treating stroke in children.

The most important medication guidelines are: 1) Ensure your child takes all medications exactly as prescribed; 2) Never discontinue any medication without first talking to the child's doctor, even if the medication does not seem to be working or is causing unwanted side effects; and 3) Follow-up with the child's health care provider as recommended to monitor the effects of the medication. Frequent blood tests are required for people taking anticoagulants to evaluate the dosage and effects of the medication.

Other stroke medications that are still being tested in clinical trials include:

• Citicoline as a treatment for ischemic stroke. Studies have shown both acute and long-term neuroprotective properties of citicoline in animal models of stroke and in several human clinical trials.
• Epoetin, a synthetic version of human erythropoietin, as a treatment for ischemic stroke. Epoetin aids the body in producing red blood cells and is currently used to treat anemia associated with kidney disease or caused by some drugs.
• Early administration of magnesium to serve as a potential neuroprotective agent. Studies have shown neuroprotectant properties of magnesium sulfate in animal models of stroke, and improved outcomes following magnesium sulfate treatment in humans have been observed following small pilot studies.

Rehabilitation

After the child's condition has stabilized, rehabilitation is initiated. Rehabilitation includes physical, occupational, and speech therapy. Therapy is usually initiated as soon as possible after a stroke and is often the most intense in the early stages of recovery. Clinicians should work with the child and the parents or caregivers to develop an individual treatment plan. Specific treatment goals will vary from one child to the next but will focus on restoring maximum function and independence, helping the child return to normal activities, and improving the child's quality of life. The child's progress after rehabilitation will depend upon which area of the brain was affected, the cause of stroke, the extent of injury, and the presence of other medical conditions.

Physical therapy includes stretching exercises, muscle group strengthening exercises, and range of motion exercises to preserve flexibility and range of motion. Exercises should be practiced daily, as recommended by the physical therapist. A physical therapist can instruct the patient on proper posture guidelines to maintain proper alignment of the hips and back. Balancing rest and exercise is also important.

Occupational therapy may include splints, casts, or braces on the affected arm or leg to enable proper limb positioning, prevent joint stiffness, and maintain flexibility and range of motion. An occupational therapist can recommend assistive equipment and devices to help the child with activities of daily living, such as bathing, dressing, and eating. If a walker or wheelchair are needed, an occupational therapist can provide specific instructions.

Physical and occupational therapists can provide guidelines on how to adapt the child's home and school environments to ensure safety and comfort.

Speech therapy will focus on the child's specific needs which may include any or all aspects of language use, such as speaking, reading, writing, and understanding the spoken word. Speech and language problems (aphasia) usually occur when a stroke affects the right side of the body.

Behavioral problems and learning disabilities, such as difficulties with attention or concentration, may become apparent when the child goes to school, so specific treatments and educational assistance may be needed to address these problems. A formal assessment can help parents identify potential behavioral and learning problems.

Surgery

The need for surgical treatment for pediatric stroke will depend on a number of factors, including the type of stroke, extent of damage from stroke, the child's age, and potential benefits and risks. Sometimes urgent surgery is necessary soon after the child is admitted to the emergency room to remove a blood clot and restore oxygen flow to the brain tissue.

Treatment options for hemorrhagic stroke may include surgery, sterotactic radiotherapy, or interventional neuroradiology to treat the underlying aneurysm or arteriovenous malformation.

There are several surgical procedures to repair an aneurysm that may have caused a hemorrhagic stroke. A clip may be placed across the neck of the aneurysm (like a clip at the end of a balloon) to stop the bleeding. A newer approach is to thread a long, thin tube through the artery that leads to the aneurysm. Then a tiny coil is fed through the tube into the aneurysm "balloon" to fill the space and seal off the bleeding.

An interventional procedure called carotid angioplasty may be performed to treat a blockage or blockages in the carotid arteries. During the procedure, a tiny balloon at the end of a long, thin tube (called a catheter) is pushed through the artery to the blockage. When the balloon is inflated, it opens the artery. In addition, a mesh tube (called a stent) may be placed inside the artery to help hold it open.

Carotid endarterectomy is a surgical procedure performed to remove a blockage from the carotid artery. During the operation, the surgeon scrapes away plaque from the wall of the artery so blood can flow freely through the artery to the brain.

Intracranial bypass surgery is a surgical procedure performed to restore blood flow around a blocked blood vessel in the brain. During the surgery, a healthy blood vessel, on the outside of the scalp, is re-routed to the part of the brain that is not getting enough blood flow. This new blood vessel bypasses the blocked vessel and provides an additional blood supply to areas of the brain that were deprived of blood. When blood flow is restored, the brain works normally, and the symptoms disappear. This procedure is not as common as the other surgical treatments listed above to treat pediatric stroke but it may be used to treat recurrent TIAs.

Alternative Treatment

Alternative and complementary therapies include approaches that are considered to be outside the mainstream of traditional health care.

Techniques that induce relaxation and reduce stress, such as yoga, Tai Chi, meditation, guided imagery, and relaxation training, may be helpful in controlling blood pressure. Acupuncture and biofeedback training also may help induce relaxation. Before learning or practicing any particular technique, it is important for the parent/caregiver and child to learn about the therapy, its safety and effectiveness, potential side effects, and the expertise and qualifications of the practitioner. Although some practices are beneficial, others may be harmful to certain patients.

Alternative treatments should not be used as a substitute for medical therapies prescribed by a doctor. Parents should discuss these techniques and treatments with the child's doctor to determine the remedies that may be beneficial for the child.

Nutritional Concerns

Dietary guidelines are individualized, based on the child's age, diagnosis, overall health, and level of functioning. Specific nutritional problems, such as swallowing or feeding difficulties, may be a concern in some patients and should be managed by a team of specialists including a speech therapist. Early identification, treatment, and correction of specific feeding problems will improve the health and nutritional status of the child.

A child's self-feeding skills can impact his or her health outcome. One study indicated that 90 percent of children with good to fair motor and feeding skills reached adulthood. In contrast, a lack of self-feeding skills was associated with a six-fold increase in mortality (rate of death).

Maintaining a healthy weight is important to prevent the development of chronic diseases such as diabetes, high blood pressure (hypertension), and heart disease.

Tube feedings may be required in some patients with failure to thrive, aspiration pneumonia, difficulty swallowing, or an inability to ingest adequate calories orally to maintain nutritional status or promote growth.

A well-balanced and carefully planned diet will help maintain general good health for children who have suffered a stroke. In general, children should follow the same low-fat, high fiber diet that is recommended for the general population.

In children older than age two, the following low-fat dietary guidelines are recommended:

• Total fat intake should comprise 30 percent or less of total calories consumed per day.
• Calories consumed as saturated fat should equal no more than 8-10 percent of total calories consumed per day.
• Total cholesterol intake should be less than 300 mg/dl per day.

If the child has high blood pressure, the DASH diet is recommended. The "Dietary Approaches to Stop Hypertension (DASH)" study, sponsored by the National Institutes of Health (NIH), showed that elevated blood pressures were reduced by an eating plan that emphasized fruits, vegetables, and low-fat dairy foods and was low in saturated fat, total fat, and cholesterol. The DASH diet includes whole grains, poultry, fish, and nuts. Fats, red meats, sodium, sweets, and sugar-sweetened beverages are limited. Sodium should also be reduced to no more than 1,500 milligrams per day.

Prognosis

Cerebrovascular disorders are among the top 10 causes of death in children, with rates highest in the first year of life. From 1979 to 1998 in the United States, childhood mortality from stroke declined sharply, by 58 percent, with reductions in all major subtypes: ischemic stroke decreased by 19 percent, subarachnoid hemorrhage by 79 percent, and intracerebral hemorrhage by 54 percent.

Some children survive a pediatric stroke with no life-long consequences. In other children, long-term complications of stroke may develop right away or within months to years after a stroke. According to a 2000 study published in the Journal of Child Neurology, the outcome of childhood stroke was a moderate or severe deficit in 42 percent of cases. Adverse outcomes after childhood stroke—including death in 10 percent, recurrence in 20 percent, and neurological deficits in two-thirds of survivors—can be reduced with available stroke treatments.

When a stroke affects a child whose brain is still developing, it is thought that the developing brain may be able to compensate for the functions that were lost as a result of a stroke.

Recovery from stroke is different with each child. Overall, the degree of permanent disability after a stroke is less in children than in adults. Speech and language problems usually improve rapidly in the first year after a stroke. Children may only have minor delays in the development of coordinated movement or in cognitive functioning. Almost all children recover the ability to walk independently after a stroke, unless there is another condition that causes disability. Recovery of function in the affected arm and hand is usually the most significant movement problem after a stroke. Most children who suffer from a stroke can expect to lead independent lives as adults.

Prevention

Despite current treatment, one out of 10 children with ischemic stroke will have a recurrence within five years. Although there is a high risk of repeat strokes in patients with sickle cell anemia, the risk can be reduced with regular blood transfusions. If no cause of the stroke was identified, the risk of a recurrence is low. If a cause was identified, the underlying condition should be treated, and anticoagulant or low-dose aspirin therapy may be initiated, depending on the child's diagnosis.

There is no screening for stroke, but screening exists for many of its risk factors. To prevent stroke, risk factors should be treated and managed by the child's primary care doctor or specialist. The doctor can advise if specific preventive treatment is needed.

Management of high cholesterol—especially high LDL (low-density lipoprotein) levels—high blood pressure and diabetes can help reduce the risk of a stroke.

Nutritional Concerns

An adequate intake of folic acid (vitamin B9) has been linked to the prevention of stroke and heart disease by lowering homocysteine, an amino acid related to the early development of cardiovascular disease when high levels are present in the blood. Dietary sources of folic acid include: vegetables, especially green vegetables; potatoes; cereal and cereal products; fruits; and organ meats (liver or kidney). It is best to eat fresh fruits and vegetables whenever possible to get the most vitamins. Recommended daily intake in micrograms (mcg) for folic acid supplements (oral tablets) include: 25–100 mcg in newborns to age three; 75–400 mcg in children aged four to six; 100-400 mcg in children aged seven to 10; and 150–400 mcg in children aged 11 and above.

Vitamin K is an important nutrient needed to regulate normal blood clotting. A diet deficient in vitamin K can cause prolonged blood-clotting time and easy bleeding and bruising. Vitamin K is found in: alfalfa, asparagus, broccoli, Brussels sprouts, cabbage cheddar cheese, green tea, green leafy lettuce, liver, seaweed, spinach, and turnip greens. Recommended daily intake for vitamin K supplements (for patients not on anticoagulant therapy) include: 10 mcg in newborns to age three; 20 mcg in children aged four to six; 30 mcg in children aged seven to 14; 65 mcg in boys and 55 mcg in girls aged 15–18; 70–80 mcg for males over age 18 and 60–65 mcg for females over age 18. If the patient is taking anticoagulant medications, vitamin K supplements are not recommended, and foods high in vitamin K are limited, since they counteract the action of the medication.

Vitamin E and beta carotene supplements were once thought to help decrease the risk of stroke and prevent the development of heart disease, but newer studies disprove their effectiveness. Researchers at The Cleveland Clinic Heart Center performed a meta-analysis of seven large randomized trials of vitamin E (given alone or in combination with other antioxidants) and eight of beta carotene. All trials included 1,000 or more patients and follow-up ranged from 1.4 to 12 years. The doses of vitamin E given in these trials ranged from 50–800 international units (IU) and 15–50 milligrams (mg) for beta carotene. The meta-analysis reviewed the effect of these antioxidants on death from cardiovascular disease or from any other cause ("all-cause mortality").

Their findings, published in the June, 2003 issue of The Lancet journal, do not support the continued use of vitamin E supplementation nor the inclusion of vitamin E in further studies. Regardless of the dosage given or the patient population, Vitamin E did not provide any benefit in lowering mortality compared to control treatments, and it did not significantly decrease the risk of cardiovascular death or stroke (cerebrovascular accident). In addition, they recommend that vitamin supplements containing beta carotene be "actively discouraged" because of the small but statistically significant increased risk of death. Researchers discourage further study of beta carotene because of the mortality risk.

Even though studies have demonstrated that vitamin E and beta carotene supplements do not reduce stroke risk, foods rich in antioxidants are still encouraged because they also contain beneficial nutrients such as flavonoids and lycopenes that are not usually included in standard oral vitamin supplements. A diet rich in antioxidant-containing foods, such as fruits, vegetables and whole grains, is linked to a reduced risk of cardiovascular disease.

Dietary supplements should not be used as a substitute for medical therapies prescribed by a doctor. Parents should discuss these nutrition supplements with the child's doctor to determine the remedies that may be beneficial for the child.

Parental Concerns

It is common for a child to feel sad or depressed after a stroke. These emotions may be the result of not knowing what to expect or not being able to do simple tasks without becoming overly tired. Temporary feelings of sadness are normal, and should gradually go away within a few weeks, as the child starts a rehabilitation program and returns to some of his or her normal routines and activities.

When a depressed mood is severe and accompanied by other symptoms that persist every day for two or more weeks, the parent should ask for a referral to a mental health professional who can help the child cope and recover. There are many treatments for depression. A healthy lifestyle including regular exercise, proper sleep, a well-balanced diet, as well as relaxation and stress management techniques can help manage depression. Major depressive disorder may be treated with antidepressants, psychotherapy (supportive counseling or "talk therapy"), or a combination of both.

Regular follow-up visits with the child's health care provider will help identify and manage risk factors and other medical conditions. If the child has a known medical condition that increases the risk of stroke, it is important for parents and caregivers to learn the warning signs and symptoms of stroke in children and infants. If the child experiences any unexpected neurological problem, the parent should have the child evaluated by a physician. Lastly, it is important for parents to carefully follow the child's treatment plan, including following the medication schedule exactly as prescribed.

Resources

Books

Burkman, Kip. The Stroke Recovery Book: A Guide for Patients and Families. Nebraska: Addicus Books, Inc., May, 1998.

Senelick, Richard C., Peter W. Rossi, and Karla Dougherty. Living with Stroke: A Guide For Families: Help and New Hope for All Those Touched by Stroke. New York: McGraw-Hill/Contemporary Books, June, 1999.

Zimmer, Judith and John P. Cooke. The Cardiovascular Cure: How to Strengthen Your Self-Defense Against Heart Attack and Stroke. New York: Broadway Books, August, 2002.

Periodicals

Abram, Harry S., MD. "Childhood Strokes: Evaluation and Treatment." Duval County Medical Society. www.dchmsonline.org/jax-medicine/1998journals/november1998/childhoodstrokes.htm.

deVeber, G., ES Roach, AR Riela, and M. Wiznitzer. "Stroke in Children: Recognition, Treatment, and Future Directions." Seminars in Pediatric Neurology. 7:4 (December, 2000): 309-317.

deVeber, G., ES Roach, AR Riela, and M. Wiznitzer. "Recognition and Treatment of Stroke in Children." Child Neurology Society Ad Hoc Committee on Stroke in Children. July, 2001.

Kirkham, FJ. "Stroke in Childhood." Archives of Disease in Childhood. 81 (July, 1999): 85-89.

Nicolaides, P. and R.E. Appleton. "Stroke in Children." Developmental Medicine and Child Neurology. 38:2 (February, 1996): 172-180.

Organizations

American Stroke Foundation. 11902 Lowell, Overland Park, KS 66213. (913) 649-1776. .

American Stroke Association, A Division of American Heart Association, 7272 Greenville Ave., Dallas, TX 75231. (888) 4-STROKE (787653). E-mail: strokeassociation@heart.org. .

Children's Hemiplegia and Stroke Association. 4101 W. Green Oaks, Ste. 305, PMB 149, Arlington, TX 76016. (817) 492-4325. E-mail: info@chasa.org. .

National Heart, Lung and Blood Institute. National Institutes of Health, Building 1, 1 Center Dr., Bethesda, MD 20892. E-mail: NHLBIinfo@rover.nhlbi. .

National Institute on Disability and Rehabilitation Research, Office of Special Education and Rehabilitative Services, U.S. Department of Education, 400 Maryland Ave. S.W., Washington, DC 20202-7100. (202) 245-7640. .

National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health. P.O. Box 5801, Bethesda, MD 20824. (800) 352-9424 or (301) 496-5751. .

National Rehabilitation Information Center (NARIC).4200 Forbes Blvd., Ste. 202, Lanham, MD 20700. (800) 346-2742 or (301) 459-5900. .

National Stroke Association. 9707 E. Easter Ln., Englewood, CO 80112-3747. (800) STROKES (787-6537) or (303) 649-9299. .

Stroke Clubs International. 805 12th St. Galveston, TX 77550. (409) 762-1022 attn. Ellis Williamson. E-mail: strokeclub@aol.com.

Web Sites

The Brain Attack Coalition. www.stroke-site.org

The Brain Matters, American Academy of Neurology Foundation. www.thebrainmatters.org

Different Strokes—A Charity for Younger Stroke Survivors. www.differentstrokes.co.uk/

HeartCenterOnline. www.heartcenteronline.com

HemiHelp—Information and Support for Children and Young People with Hemiplegia. www.hemihelp.org.uk

Pediatric Stroke Network. www.pediatricstrokenetwork.com

[Article by: Angela M. Costello]

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Stroke, or cerebrovascular accident (CVA), is the third leading cause of death (after heart disease and cancer) in the United States and the industrialized countries of the world. The term "stroke," which comes from subjects being suddenly "struck down" with neurological deficits, is commonly used by both professional and lay groups. Efforts are being made to replace the term with "brain attack" to dramatize its analogous effects to a "heart attack," the term used for myocardial infarction. The term "cerebrovascular accident" is used interchangeably with stroke ("accident" indicates the catastrophic nature of strokes, not a traumatic origin as the term implies). More than 600,000 strokes occur annually in the United States, according to the American Heart Association, and stroke prevalence (number of living stroke victims) is approximately 4.5 million with an annual cost in 1997, both direct and indirect, of over $40 billion.

Stroke refers to the usually sudden onset of a neurological deficit, such as hemiparesis (weakness on one side of the body), or aphasia (impairment of language comprehension and production), which can be attributed to either the occlusion or rupture of a cerebral vessel. Resulting specific neurological symptoms and signs are determined by the area of the brain that is affected, and since the complex functions of the brain are either localized in specialized areas or diffusely distributed, stroke symptoms may similarly be localized or generalized in nature. For example, the long pathway of motor fibers can be interrupted, with resulting hemiparesis involving various cerebral arteries or their branches, such as the anterior, middle, or vertebrobasilar arteries. Occlusion of smaller arterioles which feed smaller areas of brain may result in more isolated effects, such as pure sensory or motor hemiparesis. On the other hand, occlusion or rupture of vessels in "silent" areas of the brain, as in the frontal or parietal cortex, can lead to subtle nonfocal symptoms reflected in impaired cognition, executive function, or memory. Other symptoms of impaired specialized brain functions from strokes include apraxia (impairment in the execution of motor actions), and agnosia (loss of ability to recognize familiar objects). Leukoaraiosis, or increased T2-signal intensity, on magnetic resonance imaging (MRI) of brain white matter results predominantly from small-vessel disease, and this syndrome is associated with increased risks for strokes and dementia.

Ischemic Strokes

The causes of arterial occlusion, or ischemic strokes, are multiple. The most frequent is atherosclerotic disease of extracranial and/or intracranial arteries; the former is more common in Caucasians, while the latter is more frequent among African Americans and Asians. A thrombus (stationary blood clot) formed on atherosclerotic plaques in these locations, as well as on the aorta, can dislodge and embolize to occlude a distal artery. Strokes due to atherosclerosis account for approximately two-thirds of all strokes. If seen within three hours of stroke onset, treatment with tissue plasminogen activator (tPA), a thrombolytic agent, may substantially improve a patient's neurological outcome. Otherwise, therapeutic efforts are aimed at optimizing cerebral blood flow to ischemically impaired brain tissue, providing neural protection to avert brain damage, and maximizing neurorehabilitation. Research on stem cell and neural progenitor cell implantation into an ischemically damaged brain to promote recovery is a recently promising area of stroke research.

Transient Ischemic Attacks (TIAs). Strokes may be heralded by transient neurological deficits, called transient ischemic attacks (TIAs), such as temporary blindness of one eye (amaurosis fugax), hemiparesis, or aphasia. Most frequently, TIAs occur with significant atherosclerotic disease of the extracranial carotid arteries. Control of risk factors for atherosclerosis, such as hypertension, smoking, diabetes mellitus, elevated cholesterol, stress, and, perhaps, sedentary lifestyle, will hopefully minimize strokes from this cause to an irreducible minimum. For significant extracranial disease (>70% diameter stenosis [constriction] at the carotid bifurcation), carotid endarterectomy in competent surgical hands has been shown to reduce stroke recurrence significantly. Aspirin and other antiplatelet drugs in nonsurgical candidates can prevent subsequent strokes.

Cardiogenic strokes. Ischemic strokes can be caused by emboli from the heart as a result of more than a dozen cardiac disorders, the most common being arrhythmias, particularly atrial fibrillation (AF). Suspected cardiogenic strokes require workup, including transthoracic and transesophageal echocardiography (TTE and TEE), which can detect valvular pathologies, wall-motion abnormalities, thrombi, and patent foramen ovale (PFO). This group, in aggregate, may account for up to a quarter or more of all ischemic strokes. For AF, the treatment of choice to prevent embolic strokes is long-term anticoagulation. Patients who are not anticoagulation candidates should be treated with antiplatelet drugs. Conditions such as PFO can be treated medically with anticoagulation; surgical and percutaneous options are also available for PFO closure.

Lacunar Strokes. These strokes refer to small branch occlusions (noted previously), and include discrete syndromes such as pure sensory and motor hemiparesis. Lacunar strokes result primarily from chronic sustained hypertension, and the pathological change is "lipohyalinosis" of arterioles. This syndrome may account for 10 to 15 percent of all strokes. Adequate control of hypertension should prevent this condition.

Two final categories of diseases-causing ischemic strokes are more frequently considered in younger persons, especially those under fifty-five years of age, and involve arteries and blood elements. For the former, vessel diseases other than atherosclerosis include inflammatory processes, such as the arteritides; migraine; dissection—either spontaneous or traumatic; moyamoya syndrome; fibromuscular disorders; MELAS syndrome (mitochondrial encephalopathy, lactic acidosis, and stroke-like symptoms) and a few others. For the latter, blood-element disorders include clotting, and platelets and erythrocyte abnormalities. The most common clotting disorders are resistance to protein C activation—most frequently due to Factor V Leiden mutation (506Q); antiphospholipid syndrome, which includes the lupus anticoagulant and anticardiolipin antibodies; reduced antithrombin III; protein C & S deficiencies; plus a few others. Treatment of vascular disorders is tailored to the individual condition; for example, migraine is treated with prophylactic agents, which prevent vasospasm; arteritides with steroids and immunosuppressive agents; and moyamoya syndrome with a variety of bypass surgical procedures. Many of the hypercoagulable or prothrombotic conditions are treated with long-term anticoagulation.

Intracerebral and Subarachnoid Hemorrhages

Rupture of vessels include two large categories. The more common is intracerebral hemorrhage (ICH), which results from chronic sustained hypertension and accounts for approximately 10 percent of all strokes. An infrequent cause of ICH is amyloid angiopathy; its cause (and cure) is unknown. A second category of vessel rupture is subarachnoid hemorrhage (SAH), most frequently due to aneurysmal rupture, but occasionally from arteriovenous malformations. SAH accounts for about 5 percent of all strokes. Gene and molecular pathological markers to identify persons at risk will hopefully provide interventional tools to both prevent and treat subjects at risk before aneurysmal rupture.

ICH occurs in five brain sites, most commonly in the putamen. With substantial cerebellar ICH in a noncomatose patient, surgical evacuation can be life-saving. The only other site that may benefit from surgery is polar or white matter ICH. In neurologically viable patients, SAH can be treated successfully with surgical extirpation of the aneurysm, or with a variety of endovascular procedures, such as aneurysmal obliteration.

Public Health Importance of Strokes

As the third leading cause of death and disability, there are important public health implications for strokes, especially since many of the stroke syndromes are preventable. This is particularly true for those due to atherosclerosis, which is the most common cause of strokes. Except for increasing age, all of the risk factors for atherosclerosis can be either controlled or eliminated. To accomplish this goal, better strategies to educate and motivate the general public are vital.

In addition to controlling risk factors, a better understanding of the nature of stroke symptoms by the public is required for expeditious corrective and therapeutic measures, much as has happened with the public's general awareness of chest pain as a symptom of a potential heart attack. Investigations on proteomic and gene expression profiles for strokes to identify individuals at increased risk for strokes will hopefully provide public health planners with an even more powerful tool to intervene effectively for stroke prevention, the ultimate best treatment of strokes.

(SEE ALSO: American Heart Association; Atherosclerosis; Cardiovascular Diseases; Transient Ischemic Attacks)

Bibliography

Barnett, H. J. M.; Mohr, J. P.; Stein, B.; and Yatsu, F. M., eds. (1998). Stroke: Pathophysiology, Diagnosis & Management. Philadelphia, PA: Churchill-Livingstone.

— FRANK YATSU

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apoplexy; cerebrovascular accident

An interruption in the blood supply to the brain. Causes include a blood clot, a head injury, or an aneurysm, but the primary cause is usually disease of the heart or blood vessels, with the effects on the head being secondary. A stroke results in a part of the brain being deprived of oxygen. Small strokes may occur without symptoms and go unnoticed by the victim, but the most common manifestation is some degree of paralysis; large strokes may be fatal. Regular aerobic exercise produces a number of benefits (e.g. reduction of blood pressure in those with moderate hypertension) that can reduce the risk of a stroke.

A sudden loss of brain function caused by an interruption in the supply of blood to the brain. A ruptured blood vessel or cerebral thrombosis may cause the stroke, which can occur in varying degrees of severity from temporary paralysis and slurred speech to permanent brain damage and death.

Stroke is the third major cause of death in the Western world. It is also the commonest cause of severe physical disability occurring in people living in their own homes. It has major financial implications both for individuals and for nations.

The term 'stroke' is used to describe an acute disturbance of the brain due to an abnormality of blood supply. The onset is usually sudden and, indeed, it is this suddenness which is one of its principal characteristics. The most common initial event is weakness of the arm and leg on one side of the body (hemiplegia). About 15 per cent of 'cases' are accounted for by spontaneous bleeding into the substance of the brain — cerebral haemorrhage — usually the result of rupture of minute aneurysmal weaknesses, on one of the small arteries deep inside the brain. In the remaining 85 per cent, the underlying pathology involves 'infarction' (death of tissue), resulting from partial or complete blockage of an artery, with the resultant cutting-off of arterial blood supply.

The term 'cerebrovascular disease' is used to describe abnormalities of the arteries in the brain. The pathology of cerebral haemorrhage has been mentioned above. In the majority of cases, however, there is infarction due to arterial blockage. The underlying process involves atheroma, in which there is deposition of fatty substances on the wall of the blood vessel. The three principal results of this process are stenosis (narrowing), occlusion (blockage), and embolism, which involves the formation of a blood clot on the damaged arterial wall; this becomes dislodged and may itself produce blockage of an artery 'further on' in the arterial circulation. Cerebrovascular disease is often associated with degeneration of arteries elsewhere — particularly in the heart.

1. Can strokes be avoided?
2. Assessment of neurological deficits
3. How much recovery will occur?

1. Can strokes be avoided?

Much attention has been given in recent years to identifying 'risk factors', with a view to setting up programmes of stroke prevention. The major treatable factor is hypertension (high blood pressure). There is now clear evidence that the effective treatment of hypertension can reduce (although not eliminate) the risk of an acute stroke. This places considerable logistical demands on general practitioners and others who have the responsibility of both detecting and treating the condition.

Other risk factors are of less importance and include diabetes, cardiac disease (particularly disorders of the heart valves and of cardiac rhythm), an increased number of red blood cells (raised haematocrit), and an excessive intake of alcohol.

There has been a steady decline in the death rate from cerebrovascular disease in many parts of the world during the last 30 years. The reason for this, however, is unclear.

2. Assessment of neurological deficits

The patient usually becomes 'medically stable' within the first ten days. At the end of this time, he or she is likely to be fit enough to start the process of 'rehabilitation'. Most patients will have weakness or paralysis of the arm and leg on one side of the body (a hemiplegia). In many instances, this 'motor' loss is accompanied by impairment of sensation in the limbs. The paralysed limbs require careful positioning, and it is essential to avoid excessive pulling and stretching of the affected joints. A variety of other deficits may occur.Hemianopia. A homonymous hemianopia occurs if the visual pathways in the affected hemisphere have been damaged (see visual system: organization). If the disturbance is severe, the patient will not see objects on one side. Thus, a patient with a right homonymous hemianopia may not react to his wife and family, if they are sitting at his bedside on his right side. If mobile, he may walk into door frames and other objects on the right side.Aphasia (in this context, the terms 'aphasia' and 'dysphasia' are used synonymously) involves a disturbance of language function, and usually results from damage to the left cerebral hemisphere. In its mildest form, it may simply involve the inability to name objects such as a table, clock, or pen. In most instances, however, there is a disturbance of comprehension, and reading is impaired. In the worst cases, the patient has almost complete loss of the ability to comprehend language, and cannot speak, though, happily, the problem is rarely so severe.Visuospatial disorders. Damage to the right cerebral hemisphere often produces disorders of spatial orientation (see spatial coordination) and perception. These can be complicated and difficult to understand, but are of enormous importance to those who are caring for the stroke patient. Some patients neglect one side of the body (usually the left), and may even deny the existence of the left arm. Occasionally, the patient's perception of the arm is distorted so that it appears much longer or shorter than normal, or appears to be covered in hair. Patients with a severe disturbance of spatial function may be, for instance, unable to draw symmetrical objects, such as a house, or a clock-face, the left side of the object being usually less well drawn than the right. Such people are frequently unable to dress because they cannot organize their clothes, and may, for instance, try to don a jacket which is inside out and back to front.

A variety of other deficits may be mentioned. Apraxia involves a defect of motor programming, so that the person is unable to undertake tasks, although there is no paralysis of the affected part. Thus, the person may be unable to stick out his tongue when asked to do so, although he has no difficulty with licking his lips involuntarily. A patient with visual agnosia may be unable to recognize common objects, such as a pen or a torch, although his eyesight is satisfactory. The range of scope of cerebral disorders resulting from a stroke is large; their recognition, quantification, and management are discussed in detail in Wade et al. (1985).

Patients with an acute stroke usually remain in hospital for 4–6 weeks and are then allowed home. Their rehabilitation involves physical therapy, designed to help the patient regain lost functions, and to avoid unnecessary complications such as stiff and immobile joints, and fractures (which are often due to falling, associated with premature attempts at walking).

3. How much recovery will occur?

There is now considerable literature on the subject of recovery after stroke (for example, Skilbeck et al. 1983, Barnett, Stein, and Mohr 1986). The three adverse factors occurring in the first few days are unconsciousness, urinary incontinence, and deviation of the eyes to one side. Only 5–10 per cent of patients who are unconscious in the first week will survive, and those who do survive will usually be left very severely disabled.

About 75 per cent of disabled stroke survivors learn to walk again, though only about 20 per cent can walk at a normal speed. Many cannot, for example, get to the shops or pub. Only 15 per cent of those with a paralysed arm eventually regain normal arm function. Dysphasic patients may be expected to make about a 25 per cent improvement between three weeks and six months. In general, the amount of recovery is largely dependent upon the severity of the initial deficit: those who are severely disabled initially will usually remain with a severe permanent disability, although some recovery usually occurs. Those with a mild initial deficit may eventually make a full recovery.

(Published 1987)

— Richard Langton-Hewer

Bibliography
• Barnett, H. J. N., Stein, B. M., and Mohr, J. P. (1986). Stroke: Pathophysiology, Diagnosis and Management.
• Skilbeck, C. E., Wade, D. T., Langton Hewer, R., and Wood, V. A. (1983). 'Recovery after stroke'. Journal of Neurology, Neurosurgery, and Psychiatry, 46.
• Wade, D. T., Langton Hewer, R., Skilbeck, C. E., Bainton, D., and Burns-Cox, C. (1985). 'Controlled trial of a home-care service for acute stroke patients'. Lancet, 9 Feb.
• — —   — —   — —   and David, R. M. (1986). Stroke: A Critical Approach to Diagnosis, Treatment, and Management.

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1. a sudden and severe attack.
2. in humans, rupture or blockage of a blood vessel in the brain, depriving parts of the brain of blood supply, resulting in loss of consciousness, paralysis or other symptoms depending on the site and extent of brain damage; see also cerebral vascular accident. A very uncommon occurrence in animals.

• canine s. — see canine idiopathic vestibular syndrome.
• lightning s. — see lightning injury.
• sun s. — see heat stroke.
• s. volume — the volume of blood ejected by the left ventricle during a single ejection.

IN BRIEF: A sudden action that results in something unexpected.

Remember that not getting what you want is sometimes a wonderful stroke of luck. — The Dalai Lama

sign description: The index finger begins at the forehead. The finger pulls away and changes to a fist that strikes the opposite flat hand.

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The linear distance the piston moves inside the cylinder from top to bottom in a reciprocating engine.

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This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Stroke

Dansk (Danish)
n. - hug, slag, stød, tag, strøg, skrifttræk, slagtilfælde
v. tr. - stryge, glatte, klappe

idioms:

• a stroke of    et anfald af
• at a stroke    med et slag
• do a stroke    gøre et slag
• in one stroke    på én gang
• on the stroke of    på slaget (klokkeslæt)
• stroke of luck    udslag af held

Nederlands (Dutch)
aaien, slag, zwemslag, beroerte, streek, inslag, klap

Français (French)
n. - (gén) coup, (fig) coup, (Sport) mouvement des bras, nage, (Sport) coup d'aviron, chef de nage, (Art) trait, touche, coup de pinceau/crayon, barre oblique, coup, (Méd) congestion cérébrale, attaque, (Tech) course, caresse
v. tr. - caresser, (Sport) être le chef de nage (aviron)

idioms:

• at a stroke    d'un coup
• at one stroke    d'un seul coup
• in one stroke    d'un seul coup
• not do a stroke of work    ne rien faire, ne pas en ficher une rame
• on the stroke of    sur le coup de
• stroke of genius    (avoir) un éclair de génie
• stroke of luck    coup de chance

Deutsch (German)
n. - Strich, Schlag, Hieb, Stoß, Zug, Hub, Schachzug, Schlagmann, Schlaganfall
v. - streicheln, als Schlagmann rudern

idioms:

• at a stroke    mit einem Schlag
• at one stroke    auf einen Schlag od. Streich
• in one stroke    auf einen Schlag
• not do a stroke of work    keinen Handschlag tun, keinen Finger rühren
• on the stroke of    Punkt, Schlag
• stroke of genius    Genieschlag
• stroke of luck    glücklicher Zufall

Ελληνική (Greek)
n. - χτύπημα, πλήγμα, χτύπος, χάδι, κίνηση κολυμβητή, απλωτή, παλμός ρίψης, κονδυλιά, πινελιά, κίνηση κωπηλασίας, "κουπιά", αναπάντεχο περιστατικό, πετυχημένη προσπάθεια, (αθλοπ.) κτύπημα της μπάλας, μπαλιά, (μηχαν.) διαδρομή εμβόλου, (παθολ.) αποπληξία, (τυπογρ.) κάθετος, μπάρα
v. - χαϊδεύω, εξομαλύνω, στρώνω, κωπηλατώ

idioms:

• a stroke of    χτύπημα, κονδυλιά, πινελιά, εύνοια (της τύχης)
• at a stroke    μονομιάς, μια και καλή, με ένα χτύπημα
• do a stroke    κάνω ελάχιστη (δουλειά)
• in one stroke    με ένα χτύπημα
• on the stroke of    με το που σήμανε
• stroke of luck    εύνοια της τύχης

Italiano (Italian)
accarezzare, tratto, botta, carezza, bracciata, colpo apoplettico, tocco, colpo di fulmine

idioms:

• a stroke of    un colpo di
• at a stroke    d'un colpo, all'improvviso
• do a stroke    fare un po'
• in one stroke    d'un sol colpo
• on the stroke of    al battere delle
• stroke of luck    colpo di fortuna

Português (Portuguese)
n. - curso (m) (Mec.), impacto (m), apoplexia (f) (Med.)
v. - acariciar

idioms:

• a stroke of    um golpe de
• at a stroke    de um golpe
• do a stroke    acariciar
• in one stroke    de um só golpe
• on the stroke of    ao dar (horas)
• stroke of luck    golpe de sorte

Русский (Russian)
удар, припадок, взмах, прием, неожиданный случай, штрих, мазок, черта, бой часов, биение (сердца), стиль (плавания), ход (поршня), поглаживание рукой, похвала, задавать темп, испещрять полосами, перечеркивать, гладить, хвалить, уговаривать

idioms:

• a stroke of    удача
• at a stroke    сразу, одним ударом
• do a stroke    делать что-л.
• in one stroke    одним ударом
• on the stroke of    точно в такой-то час
• stroke of luck    удача, везение

Español (Spanish)
n. - línea, golpe, cachetazo, caricia, brazada, tacada, apoplejía, ataque, brochazo, pincelada, rayo
v. tr. - acariciar, frotar suavemente, pasar suavemente la mano, alisar, irritar a uno, ordeñar, poner tilde o trazo

idioms:

• at a stroke    de una vez, de un golpe
• at one stroke    de una vez, de un golpe, inmediatamente
• in one stroke    de un plumazo
• not do a stroke of work    no hacer absolutamente nada
• on the stroke of    en punto
• stroke of genius    rasgo de ingenio, genialidad
• stroke of luck    un golpe de suerte

Svenska (Swedish)
n. - slag, hugg, stöt, slaglängd, simsätt, rodd, roddsätt, drag, grep, strykning
v. - stryka, smeka, blidka, släta till, glätta

中文（简体）(Chinese (Simplified))
1. 打, 敲, 击, 一抽, 打法, 一击, 一划, 划法, 敲声, 鸣声, 画短线于, 抽, 勾销, 删掉

idioms:

• a stroke of    一笔, 一举, 一着, 成功的努力
• at a stroke    一笔, 一下子, 一举
• do a stroke    来做一点事
• in one stroke    一笔, 一下子, 一举
• on the stroke of    准时地, 准点地
• stroke of luck    交了一子好运

2. 抚, 捋, 摸

中文（繁體）(Chinese (Traditional))
1.
v. tr. - 撫, 捋, 摸
n. - 撫, 捋, 摸

2.
n. - 打, 敲, 擊, 一抽, 打法, 一擊, 一劃, 劃法, 敲聲, 鳴聲
v. tr. - 畫短線於, 擊, 抽, 勾銷, 刪掉
v. intr. - 勾銷, 刪掉

idioms:

• a stroke of    一筆, 一舉, 一著, 成功的努力
• at a stroke    一筆, 一下子, 一舉
• do a stroke    來做一點事
• in one stroke    一筆, 一下子, 一舉
• on the stroke of    準時地, 準點地
• stroke of luck    交了一子好運

한국어 (Korean)
n. - 타격, (벼락의) 일격
v. tr. - ~에 선을 긋다, (공을) 치다

idioms:

• a stroke of    일격
• at a stroke    일격으로, 단번에, 일거에
• do a stroke    수완, 솜씨, 성공
• in one stroke    한 번 쳐서

日本語 (Japanese)
n. - 打つこと, ひと打ち, ストローク, ひと動作, ひとかき, 脈拍, ひと彫り, ひと筆, 打つ音, なでること, 一撃, 筆づかい
v. - なでる, 線を引く, ボールを打つ

idioms:

• a stroke of    一撃, 発作
• at a stroke    一撃で
• do a stroke    ひと仕事する
• in one stroke    一度に沢山の事をやり遂げる
• on the stroke of    ちょうど～時に
• stroke of luck    幸運の訪れ

العربيه (Arabic)
‏(الاسم) ضربه, جلطه, حركه مباغته, دقه (فعل) داعب, لاطف, ملمس, مسد‏

עברית (Hebrew)
n. - ‮מכה, שבץ, חבטה, תנועה, הצלפה, משוטאי אחורי, לטיפה, משיכת-קולמוס, תנועת-מכחול, צלצול-שעון, סיסוב, שיטת חבטה במחבט, שחייה בסגנון חתירה, תנועת בוכנה, מאמץ מיומן‬
v. tr. - ‮ליטף, חתר במשוט אחורי, היכה, חבט‬

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