stroke

Stroke

 

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 also is sometimes called a brain attack or a cerebrovascular accident (CVA).

Some important stroke statistics include:

• more than one-half 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 160,000 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 but they can occur at any age
• 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 in the twenty-first century. However, about two-thirds of stroke survivors will have disabilities ranging from moderate to severe.

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, or 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, is an important step 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 heart beat. 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 become fatal. Nonetheless, recovery may be more complete for a person who survives hemorrhage than for one who survives a clot, because the blood deprivation effects usually are 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, use of certain medications, and lifestyle choices:

• Age and sex. The risk of stroke increases with age, doubling for each decade after age 55. Men are more likely to have a stroke than women.
• Heredity. Blacks, Asians, and Hispanics 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.
• Hormone replacement therapy. In mid-2003, a large clinical trial called the Women's Health Initiative was halted when researchers discovered several potentially dangerous effects of combined hormone replacement therapy on postmenopausal women. In addition to increasing the risk of some cancers and dementia, combined estrogen and progesterone therapy increased risk of ischemic stroke by 31% among study participants.
• 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, often described as "the worst headache of my life"
• 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 scan (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

Emergency treatment

Emergency treatment of stroke from a blood clot is aimed at dissolving the clot. This "thrombolytic therapy" currently is performed most often with tissue plasminogen activator, or t-PA. 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. t-PA therapy has been shown to improve recovery and decrease long-term disability in selected patients. 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 is the most common treatment. Corticosteroids also may 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.

Rehabilitation

Rehabilitation refers to a comprehensive program designed to 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 of medical professionals and may include the services of a neurologist, a physician who specializes in rehabilitation medicine (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.

A hemorrhagic stroke (left) compared to a thrombotic stroke (right).

(Illustration by Hans & Cassady, Inc.)

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 also may 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 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, the functions of that tissue may be performed by other brain regions 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 caregiver 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.

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. A 2003 study found that treating people who have had a stroke with certain antidepressant medications, even if they were not depressed, could increase their chances of living longer. People who received the treatment were less likely to die from cardiovascular events than those who did not receive antidepressant drugs.

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:

• quitting smoking
• controlling blood pressure
• getting regular exercise
• keeping body weight down
• avoiding excessive alcohol consumption
• getting regular checkups and following the doctor's advice regarding diet and medicines, particularly hormone replacement therapy.

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. A new drug called ximelagatran (Exanta) with fewer side effects has been introduced in Europe. The drug's manufacturer was applying for FDA approval to market the drug for use in preventing stroke and other thromboembolic complications in early 2004.

In 2003, physicians at the Framingham Heart Study derived new risk scores to help physicians determine which patients with new onset of atrial fibrillation are at higher risk for stroke alone or for stroke or death. 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

Periodicals

"HRT Increases Risk of Dementia and Stroke." Contemporary OB/GYN July 2003: 16-21.

"New Classification Scheme Helpful to Predict Risk of Stroke or Death." Heart Disease Weekly September 14, 2003: 3.

"New Drug Application Submitted to FDA for Exanta." Heart Disease Weekly January 25, 2004: 79.

"New Stroke Prevention Drug." Chemist & Druggist September 13, 2003: 24.

"Post-stroke Antidepressant Treatment Appears to Reduce Death Rate." Heart Disease Weekly October 26, 2003: 56.

Organizations

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

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

Key terms

Aneurysm — A pouchlike bulging of a blood vessel. Aneurysms can rupture, leading to stroke.

Atrial fibrillation — A disorder of the heart beat associated with a higher risk of stroke. In this disorder, the upper chambers (atria) of the heart do not completely empty when the heart beats, which can allow blood clots to form.

Cerebral embolism — A blockage of blood flow through a vessel in the brain by a blood clot that formed elsewhere in the body and traveled to the brain.

Cerebral thrombosis — A blockage of blood flow through a vessel in the brain by a blood clot that formed in the brain itself.

Intracerebral hemorrhage — A cause of some strokes in which vessels within the brain begin bleeding.

Subarachnoid hemorrhage — A cause of some strokes in which arteries on the surface of the brain begin bleeding.

Tissue plasminogen activator (tPA) — A substance that is sometimes given to patients within three hours of a stroke to dissolve blood clots within the brain.

stroke

 [strōk]

1. a sudden and severe attack.

2. stroke syndrome.

A, Stroke. B, Areas of the body affected by a stroke. From Frazier et al., 2000.

heat stroke a condition caused by exposure to excessive heat; see also sunstroke.

stroke

(strōk), [MIM*601367]

1. Any acute clinical event, related to impairment of cerebral circulation, that lasts longer than 24 hours.
See also: stroking. Synonym(s): apoplexy, brain attack

2. A harmful discharge of lightning, particularly one that affects a human being.
See also: stroking.

3. A pulsation.
See also: stroking.

4. To pass the hand or any instrument gently over a surface.
See also: stroking.

5. A gliding movement over a surface.

[A.S. strāc]

An acute neurologic deficit resulting from circulatory impairment that resolves within 24 hours is called a transient ischemic attack (TIA); most TIAs last only 15-20 minutes. In contrast, a stroke involves irreversible brain damage, the type and severity of symptoms depending on the location and extent of brain tissue whose circulation has been compromised. The outcome of a stroke varies from minimal impairment to rapid onset of coma followed quickly by death. Stroke ranks third as a cause of death in adults in the U.S., after ischemic heart disease and cancer. About 600,000 people a year experience strokes in this country, of which about one fourth are fatal. At any given time the population includes about 3 million stroke survivors. Stroke costs the U.S. national economy more than $40 billion a year. The incidence of stroke has gradually declined during the past generation. Risk factors for stroke include hypertension, valvular heart disease or the presence of a prosthetic valve, atrial fibrillation, left ventricular dysfunction, hyperlipidemia, diabetes mellitus, cigarette smoking, obstructive sleep apnea, a history of previous stroke or TIA, and a family history of stroke. In addition, prolonged estrogen replacement therapy, elevation of plasma homocysteine, low circulating levels of folic acid and pyridoxine (vitamin B6), periodontal disease, and chronic bronchitis are all independent risk factors. Ischemic stroke, which accounts for about 85% of all strokes, is generally caused by atherothrombosis or embolism of a major cerebral artery. Less common causes of ischemic stroke include nonatheromatous vascular disease and coagulation disorders. Severe, acute ischemia in nerve tissue triggers cellular changes (calcium influx, protease activation) that can swiftly cause irreversible damage (infarction). Around the infarct zone lies a so-called penumbra of ischemic, electrically silent tissue that may be salvageable by prompt reperfusion. The mortality of ischemic stroke is 15-30% within the first 30 days. Hemorrhagic stroke, which makes up the other 15%, has a graver prognosis, with a 30-day mortality rate of 40-80%. Carriers of either the e2 or e4 allele of the apolipoprotein E (APOE) gene have an elevated risk of intracerebral hemorrhage. About 30% of ischemic infarcts, including most of those with severe impairment of cerebral blood flow and extensive tissue death, eventually develop a hemorrhagic component. The diagnostic evaluation of the patient with stroke includes history, physical examination, hematologic studies with coagulation profile, blood chemistries, electrocardiogram, and imaging studies. Although cranial CT without contrast enhancement is the procedure of choice to distinguish ischemic from hemorrhagic stroke and to identify subarachnoid hemorrhage, MRI is a more sensitive indicator of parenchymal hemorrhage as well as of early ischemia and infarction, and is more useful in assessing the brainstem and cerebellum and in identifying underlying nonvascular lesions. About 20% of people initially thought to have had a stroke prove to have some other disorder, and as many as 20% of strokes are missed on initial evaluation by emergency department physicians. Early and aggressive treatment is crucial in limiting damage to brain tissue and achieving an optimal outcome. In ischemic stroke, intravenous administration of tissue plasminogen activator (TPA) within the first 3 hours, with the purpose of dissolving an obstructing thrombus, has been shown to improve overall outcome at 90 days. Limiting factors in the use of thrombolytic therapy are the need to rule out hemorrhagic stroke (sometimes difficult with available imaging methods) and the fact that the therapy itself may induce hemorrhage. Intravenous thrombolytic agents other than TPA are not only less effective but also more likely to cause hemorrhage. During the acute phase of a stroke, respiratory and circulatory support and attention to fluid and electrolyte balance and nutrition are vitally important. Hypothermia and intravenous administration of heparin and magnesium also improve outcome in selected cases. Long-term consequences may depend on the aggressiveness and persistence of physical therapy and rehabilitation. About 40% of stroke victims develop depression, a complication that aggravates cognitive impairment and delays recovery. Effective measures for the prevention of stroke include aggressive management of hypertension (relative risk reduction, 30-50%), hyperlipidemia (30-40%), and diabetes mellitus; cessation of smoking; and chemoprophylaxis in patients at high risk. Administration of aspirin (acetylsalicylic acid) prophylactically inhibits platelet aggregation by suppressing thromboxane A₂. Metaanalysis of randomized controlled trials involving a total of more than 50,000 people indicated that low-dose aspirin (81-325 mg/day) reduces the risk of ischemic stroke by 39 events per 10,000 people but increases the risk of hemorrhagic stroke by 12 events per 10,000 people. Other studies suggest that aspirin at higher dosage (1.3 g/day in divided doses) protects men but not women from ischemic stroke because in women aspirin also suppresses prostacyclin, a natural inhibitor of platelet aggregation. Prophylaxis with other antiplatelet agents (clopidogrel, ticlopidine) is equally effective in men and women and at least as protective as aspirin. In nonvalvular atrial fibrillation, warfarin prophylaxis reduces stroke risk by two thirds. In people with carotid artery stenosis of more than 70%, carotid endarterectomy clearly reduces the risk of stroke. The National Stroke Association has recommended adoption of the term brain attack for stroke, by analogy with the familiar heart attack, to emphasize to the public both the location of the lesion and the urgency of the need for assessment and treatment. see also tissue plasminogen activator.

stroke

(strōk)

1. a sudden and severe attack.

2. stroke syndrome.

3. a pulsation.

---

completed stroke  stroke syndrome reflecting the infarction of the vascular territory that is put at risk by a stenosis or occlusion of a feeding vessel.

embolic stroke  stroke syndrome due to cerebral embolism.

stroke in evolution  a preliminary, unstable stage in stroke syndrome in which the blockage is present but the syndrome has not progressed to the stage of completed stroke.

heat stroke  a condition due to excessive exposure to heat, with dry skin, vertigo, headache, thirst, nausea, and muscular cramps; the body temperature may be dangerously elevated.

thrombotic stroke  stroke syndrome due to cerebral thrombosis, most often superimposed on a plaque of atherosclerosis.

stroke

(strōk)

n.

1. The act or an instance of striking, as with the hand, a weapon, or a tool; a blow or impact.

2. A sudden severe attack, as of paralysis or sunstroke.

3. 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.

stroke

See cerebrovascular accident.

stroke

A clinical syndrome consisting of rapidly developing clinical signs of focal (at times global) disturbance of cerebral function, lasting more than 24 hours or leading to death, with no apparent cause other than that of vascular origin.

stroke

Cerebrovascular accident Neurology A sudden focal neurologic defect lasting > 24 hrs, which is characterized by abrupt loss of consciousness due to either hemorrhage or vascular occlusion of cerebral blood vessels, leading to immediate paralysis, weakness, speech defects; a sudden onset of neurologic deficit of vascular origin; strokes are a leading cause of disability in developed countries–500,000 new victims/yr, US, 20-30% of whom are left with severe residua; strokes are the 3^rd leading cause of death–20-30% early mortality; the incidence of stroke rises dramatically with age; the risk doubles every decade after age 35 Statistics, mortality < 80 deaths/105: Whites in US–especially in the midwest, Australia, New Zealand, northern Europe, Egypt; >130 deaths/105: Black US–especially in south, Russia, mainland China, former Eastern Blocks, Argentina Clinical Paralysis, weakness, sensory loss, speech defects Etiology ASHD, dissection or stenosis of carotid artery, cocaine, embolism, HTN, fibromuscular dysplasia, syphilis Treatment Warfarin ↓ risk of stroke in Pts with A Fib or previous MI; in poor candidates for warfarin therapy, aspirin–which is less protective ± ticlopidine; carotid endarterectomy–useful if 70+% stenosis; CE's role in asymptomatic Pts is uncertain; dipyridamole and sulfinpyrazone are useless. See Completed stroke, Delayed stroke, Embolic stroke, Hemorrhagic stroke, Recent completed small stroke, Sunstroke, Working stroke.

stroke

(strōk)

1. Any acute clinical event, related to impairment of cerebral circulation, which lasts longer than 24 hours.
See also: cerebrovascular accident

2. A harmful discharge of lightning, particularly one that affects a human being.

3. A pulsation.

4. To pass the hand or any instrument over a surface.
See also: stroking

5. A gliding movement over a surface.
Synonym(s): apoplexy.

[A.S. strāc]

stroke

(strok) [ME.]

HEMORRHAGIC STROKE: Bleeding into the brain, seen on noncontrast head CT (Courtesy of Harvey Hatch, MD, Curry General Hospital)

1. A sudden loss of neurological function, caused by vascular injury (loss of blood flow) to an area of the brain. Stroke is both common and deadly: about 700,000 strokes occur in the U.S. each year. Stroke is the third leading cause of death in the U.S. Because of the long-term disability it often produces, stroke is the disease most feared by older Americans. In the U.S., 80% of strokes are caused by cerebral infarction (i.e., blockage of the carotid or intracerebral arteries by clot or atherosclerosis); intracranial hemorrhage and cerebral emboli are responsible for most other strokes. Innovations in the management of stroke (e.g., in prevention, the early use of thrombolytic drugs, vascular ultrasonography, and endarterectomy) have revolutionized the acute and follow-up care of the stroke patient. Synonym: apoplexy; attack, brain; cerebrovascular accident See: carotid endarterectomy; intracranial hemorrhage; transient ischemic attack; illustration; table

Etiology

Risk factors for stroke include advanced age (esp. older than 65 years), atherosclerosis of the aortic arch, atrial fibrillation, carotid artery disease, cigarette use, excessive alcohol use (more than 5 drinks daily), heart failure, hyperlipidemia, hypertension, a history of myocardial infarction, diabetes mellitus, male gender, close relation of someone who has had a stroke, nonwhite race, peripheral vascular disease, physical inactivity, obesity, using combination hormonal contraception (the pill, ring, patch), being pregnant or immediately postpartum, or a recent transient ischemic attack.

Symptoms

The National Institute of Neurological Disorders and Stroke lists the following symptoms as warning signs of stroke: sudden weakness or numbness of the face, arm, or leg; sudden loss of vision, double vision, dimming of vision in one or both eyes; sudden difficulty speaking or understanding speech; sudden severe headache; and sudden falling, gait disturbance, or dizziness. The patient who experiences these problems should call 911 immediately. If symptoms disappear in a few minutes, the individual may have experienced a transient ischemic attack (TIA [informally known as a “ministroke” or a “warning stroke”]) and should notify his/her primary care provider immediately for preventive care. In clinical practice, stroke patients often present with more than one stroke symptom (e.g., limb paralysis and aphasia; severe headache and hemibody deficits). It is also important to note that these symptoms are not specific for stroke: sudden dizziness or gait disturbance can occur as a result of intoxication with drugs or alcohol, for example, and sudden severe head pain can result from cluster headache, migraine, and many other disorders.

Treatment

Acute ischemic stroke can be treated with recombinant tissue plasminogen activator (rt-PA) if the disease is recognized in the first 90 to 180 min and intracerebral hemorrhage has been excluded with urgent computed tomography (CT) or magnetic resonance imaging (MRI) scanning of the brain. This form of therapy is not without risk; thrombolytic drugs can reduce the potential for long-term disability and death by 20%, but increase the risk of hemorrhage. Hemorrhagic strokes, which have about a 50% mortality, can sometimes be treated by evacuating blood clots from the brain or by repairing intracerebral aneurysms.

CAUTION!

Patients with hemorrhagic stroke should never receive fibrinolytic drugs. Other contraindications to fibrinolysis in stroke include recent or active bleeding or a known propensity for abnormal bleeding; recent lumbar puncture; recent arterial puncture; recent myocardial infarction; recent surgery or major trauma; seizure at the onset of the stroke; or blood pressure over 185/110 that does not improve with simple therapies.

Patient care

Acute phase: The health care team performs a history and physical assessment, including a careful examination of airway, breathing, circulation, and neurological functions. The Glasgow Coma Scale should be used to assess level of consciousness. The severity of a stroke should be assessed with a valid scale, such as the National Institute’s of Health Stroke Scale (NIHSS) or other well-publicized assessment tools. Staff provides oxygen by nasal cannula, establishes venous access via two large-bore catheters, and infuses saline intravenously; obtains blood samples for complete blood count, blood glucose, electrolytes, and coagulation studies; and obtains a 12-lead ECG and initiates cardiac monitoring. The stroke team, neurologist, radiologist, and MRI and/or CT technician are alerted. Fever and hyperglycemia are treated aggressively because elevated body temperatures and elevated blood glucose levels have been linked to poorer outcomes. Blood pressure is gently controlled to a level less than 180/110: more aggressive pressure control may be hazardous. The patient is positioned in the lateral or semiprone position with the head elevated 15 to 30 degrees to decrease cerebral venous pressure. Neurological status is monitored for signs of deterioration or improvement, and findings are documented on a flow sheet. The National Institute of Neurological Disorders and Stroke (NINDS) suggests the following order of assessment in patients with suspected stroke: level of consciousness, eye movements, visual fields, facial movements, motor function of arms and legs, limb coordination, sensory responses, and language use including clarity of speech. A history of the incident is obtained, including how and when symptoms started. Past medical history should be reviewed (hypertension, use of anticoagulant drugs, cardiac dysrhythmias). The patient is prepared for prescribed diagnostic studies, including MRI and/or CT, and possibly arteriography.

The patient is oriented frequently and reassured with verbal and tactile contacts. Attention is focused on determining the patient’s candidacy for emergent use of thrombolytic therapy. If potential benefits are established, recombinant tissue plasminogen activator (rt-PA) is administered intravenously over 60 min, with 10% of the determined dosage as a bolus in the first 60 sec. Blood pressure is monitored closely once the infusion is started, and any elevation treated aggressively. The patient also is monitored for indications of systemic bleeding (tachycardia, tachypnea, hypotension or acute hypertension, rapid mental status deterioration, severe headache, and nausea and vomiting). When rt-PA administration is complete, the patient is transferred to the neurologic ICU or neurology unit. If clot-busting drugs cannot or should not be administered, monitoring and supportive care is provided. The ability to speak is assessed, and if aphasia is present, a consultation by a speech therapist is obtained. Bladder function is assessed; noninvasive measures are used to encourage voiding in the presence of urinary retention, voiding pattern is determined, and the incontinent patient is kept clean and dry. Use of indwelling catheters is limited because these promote urinary tract infection. Bowel function is assessed, and dietary intervention and stool softeners or laxatives as necessary are used to prevent constipation. Straining at stool or use of enemas is avoided. Fluid and electrolyte balance (intake, output, daily weight, laboratory values) is monitored and maintained. Adequate enteral or parenteral nutrition is provided as appropriate. Nursing measures are instituted to prevent complications of immobility. In consultation with occupational therapists and physical therapists, a program of positioning and mobility is initiated, as appropriate. Examples of activities include repositioning at least every 2 hr, maintaining correct body alignment, supporting joints to prevent flexion and rotation contractures, and providing range-of-motion exercises (passive to involved joints, active-assisted or active to uninvolved joints). Irrigation and lubrication prevent oral mucous membranes and eyes (cornea) from drying. Prescribed medical therapy is administered to decrease cerebral edema, and antihypertensives or anticoagulants are given as appropriate for etiology. The patient is observed for seizure activity, and drug therapy and safety precautions are initiated. Most stroke patients are hospitalized for a few days. Patient education about risk modification begins prior to discharge.

Rehabilitative phase: After the acute phase of stroke, rehabilitation goals depend on the severity of the patient's deficit, the age of the patient, the presence of comorbidities and prior functional status, his or her ability to perform activities of daily living independently, and the family and social support systems available. The rehabilitation program will consist of various types of exercises, including neuromuscular retraining, motor learning and motor control, and functional activities that emphasize relearning or retraining in basic skills required for self-care. This may include instruction in the use of adaptive and supportive devices to facilitate independence in daily tasks. The goal of rehabilitation is to achieve an optimal functional outcome that will allow the patient to be discharged to the least restrictive environment. Ideally, the patient will achieve sufficient independence to return to community living, either independently or with family and community support.

All patient efforts should receive positive reinforcement. Patient communication is a priority. Exercises, proper positioning, and supportive devices help to prevent deformities. Quiet rest periods are provided based on the patient's response to activity. The patient should either assist with or perform own personal hygiene and establish independence in other activities of daily living. The rehabilitation team evaluates the patient's ability to feed self and continues to provide enteral feeding as necessary. A bowel and bladder retraining program is initiated, and both patient and family receive instruction in its management. Both patient and family are taught about the therapeutic regimen (activity and rest, diet, and medications), including desired effects and adverse reactions to report. Emotional lability, a consequence of some strokes, is recognized and explained, and assistance is provided to help the patient deal with changes in affect.

Note

The best results are achieved by patients treated in specialized treatment centers with demonstrably low complication rates. All stroke patients are advised to reduce their risk for future stroke by taking prescribed antihypertensive drugs as directed; losing excess weight; exercising regularly; eating a well-balanced diet low in fat, cholesterol, sugar, and salt; stopping smoking; limiting alcohol intake; and maintaining glycemic control. Patient and family are referred to the American Stroke Association or local stroke groups for information and support (http://www.strokeassociation.org).

2. To rub gently in one direction, as in massage.

3. A gentle movement of the hand across a surface.

4. In dentistry, a complete simple movement that is often repeated with modifications of position, strength, or speed, perhaps as a part of a continuing activity; e.g., the closing stroke in mastication when the jaw closes and the teeth come together. In scaling or planing the roots of teeth, the scaling instrument is introduced carefully into the subgingival area in what is called an exploratory stroke, perhaps followed by a power stroke designed to break or dislodge encrusted calculus. This is followed by a shaving stroke, intended to smooth or plane the root surface.

5. A sharp blow.

ischemic stroke

A stroke caused by diminished blood flow to a particular artery in the brain, e.g., as a result of a clot in the artery or an embolus lodging in the artery. Ischemic stroke is much more common than hemorrhagic stroke.

lacunar stroke

A pathological change in the brain caused by diminished or no blood flow through one of the brain's small penetrating arteries. When this occurs, there may be no clinically detectable changes in the patient or signs and symptoms of stroke. A group of little strokes may cause progressive dementia.

mini-stroke

A colloquial and imprecise term for a transient ischemic attack.

paralytic stroke

A stroke that produces loss of muscular functions.

Cause of Stroke	Frequency of Occurrence
Emboli from other organs, e.g., heart	about 15%
Cerebrovascular disease	greater than 50%
Trauma	less than 5%
Hypercoagulable states	less than 5%
Unknown	about 25%

stroke

The effect of acute deprivation of blood to a part of the brain by narrowing or obstruction of an artery, usually by thrombosis (80 %), or of damage to the brain substance from bleeding into it (CEREBRAL HAEMORRHAGE) (15%). Subarachnoid haemorrhage is the cause in 5%. The results of such damage are most obvious if they involve the nerve tracts concerned with movement, sensation, speech and vision. These are situated close together, in the internal capsule of the brain, and are often involved together. There may be paralysis and loss of sensation down one side of the body or of one side of the face, loss of corresponding halves of the fields of vision, a range of speech disturbances or various disorders of comprehension or expression. In most cases a degree of recovery, sometimes considerable, may be expected. Haemorrhage into the brainstem, where the centres for the control of the vital functions of breathing and heart-beat are situated, is the most immediately dangerous to life. Diagnosis of the type of stroke is important and this requires neuroimaging of the brain.

cerebrovascular accident

; CVA; stroke rapidly developing focal dysfunction of brain tissue persisting for longer than 24 hours, commonly caused by interruption of normal blood supply to brain or spinal cord (e.g. infarction), exacerbated by atherosclerosis and thrombus formation; 1:3 of those affected by CVA are aged less than 65 years; patients with diabetes mellitus are especially prone to CVA; CVA effects vary widely, and presenting features depend on extent and location of central nervous system damage; third most common cause of death in the UK: 20% die within 1 month of CVA and 50% of survivors show permanent change in physical capability, speech and language, cognitive or emotional function; cause of major mobility impairment, e.g. hemiplegia, with footdrop and circumductory gait; surviving CVA cases are likely to be on lifelong anticoagulant therapy, e.g. warfarin or aspirin

stroke,

n 1., a massage technique that involves pressure or movement of the therapist's hand or arm across the body's surface.
2., a condition in which hemorrhage or occlusion of a cerebral blood vessel leads to ischemia and tissue damage to the brain. May result in changes in speech or sensation, weakness, paralysis, and death.

ophthalmodynamometer (ODM) 

1. Instrument for measuring the near point of convergence of the eyes.

2. Instrument for measuring the blood pressure of the central retinal artery. There are two types: the compression type (e.g. Bailliart's ophthalmodynamometer) in which the pressure is raised by pressing on the eye, the force being produced by a spring-loaded plunger resting on the temporal bulbar conjunctiva of the anaesthetized eye, while the examiner observes the optic nerve through an ophthalmoscope. The other type is by suction in which negative pressure is applied to the eye using a scleral vacuum cup near the limbus (e.g. Doppler's ophthalmodynamometer). The diastolic pressure is read from the gauge provided with the instrument when the central retinal artery is seen to pulsate on the optic disc and the systolic pressure is read when all arterial pulsations just cease (the instrument should be removed immediately afterwards). A low systolic pressure is indicative of an occlusive disease of the carotid artery (a comparison between the two eyes is also very informative) as such disorders are responsible for a significant percentage of ocular symptoms and strokes. See amaurosis fugax; Hollenhorst's plaques.

stroke

(strōk) [MIM*601367]

1. Single unbroken movement of an instrument in the task it was designed to perform.

2. To pass the hand or any instrument gently over a surface.

3. A gliding movement over a surface.

[A.S. strāc]

stroke,

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

stroke, circular,

n an unbroken spherical movement of approximately 1 to 2 mm in diameter, combined with pressure, that is used to apply paste in polishing.

stroke, circumferential

n a movement used for root and gingival curettage; the blade of the periodontal curet is negotiated mesiodistally while it is in contact with either the root or the inner aspect of the soft tissue wall of the gingival or periodontal pocket.

stroke, exploratory,

n a phase of subgingival root scaling in which the curet is held in a featherlike grasp to ascertain tactilely the amount and extent of the deposits on the root surface; the ingress stroke into the pocket area.

stroke, horizontal,

n a short movement against a tooth that is made parallel to its occlusal surface.

stroke, oblique,

n a single, continuous diagonal movement of an instrument over the external face of the object being worked on.

stroke, placement,

n a single, continuous movement of an instrument over the surface of an object being worked on, which moves the instrument at the intended location.

stroke, power,

n the phase of the working stroke that is designed to split or dislodge calculus from the root surface. It is prefaced by the exploratory stroke and followed by the shaving stroke.

stroke, probe walking,

n the technique of assessing the progression and extent of disease within the oral cavity by inserting a periodontal probe into the sulcus or pocket of the tooth and moving the device up and down between 1 to 2 mm in height while simultaneously advancing forward in 1 mm increments.

stroke, pull,

n a single, continuous movement of an instrument over the surface of an object being worked on. A pull stroke is enacted to remove calculus from the surface of a tooth.

stroke, push and pull,

n the technique of using a subgingival explorer vertically or diagonally to assess a defect of the tooth's surface by inserting the lower shank of the instrument under the gingival margin and into the sulcus or pocket and moving the device up and down while simultaneously applying equal pressure and advancing forward.

stroke, shaving,

n the phase of the working stroke of a periodontal curet that is designed to smooth or plane the root surface. It follows the power stroke, which is designed to dislodge calculus from the root surface.

stroke, vertical,

n a single, continuous movement of an instrument over the external face being treated. The vertical stroke is in a direction that parallels the length of the tooth (from the root to the occlusal surface).

stroke volume,

n the volume of blood put out by the heart per heartbeat. It is directly proportional to the volume of blood filling the heart during diastole.

stroke, working,

n a single, continuous movement of an instrument that achieves a task or treatment.

stroke

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 stroke

see canine idiopathic vestibular syndrome.

lightning stroke

see lightning injury.

sun stroke

see heat stroke.

stroke volume

the volume of blood ejected by the left ventricle during a single ejection.

Patient discussion about stroke

Q. Stroke My granny got stroke. Now she is in the hospital, but she doesn't identify me or my mother. When I asked her what are the season now - she answers that it's winter now. I don't know how to help her. What I have to prepare for?

A. I was sorry to hear about your grandmother. You should remeber that after the initial phase, there may be changes in her functioning, especially with rehabilitation program. It's a vast subject, so you can read about it here (http://www.stroke.org.uk/information/after_a_stroke/), and also talk to other people in the stroke community here (http://www.imedix.com/Stroke)

Q. Migraine stroke Hi, I'm 58 years-old male and I have migraines with aura since age 14. Two weeks ago, I felt weakness in the left side of my body, and at the hospital the doctors told me I had a stroke. I underwent several tests, but they still don't know the cause for the stroke (my lab tests are normal; I don't have diabetes or hypertension). My neurologist said that although it's very rare, he thinks that my stroke was caused by my migraine. I tried to find information about it, but couldn't find much – do you know where I can get some more info? Thanks!

A. I supposedly had two strokes that caused one sided weakness and temporary aphasia. The most recent time it happened, I went to a different hospital's ER where their neurologist and stroke specialist told me I have "complex migraines." Apparently this type of migraine can mimic a stroke with all the symptoms. If you look up "complex migraine" at webmd.com or other similar sites, it will give you more informaton. My opinion, for what it's worth, is that I'd rather have a migraine than another stroke since migraines can be treated with preventive meds and/or meds that help the symptoms once it gets started.

Q. What Are the Risk Factors for Developing Stroke? My father had a stroke recently, at the age of 73. What are the risk factors for developing this?

A. Primary risk factors include:

1) smoking
2) excessive alcohol intake
3) uncontrolled high blood pressure
4) high cholesterol
5) overweight/unhealthy diet
6) illegal drugs/abuse of Rx drugs
7) known or unknown heart problems
8) diabetes
9) known or unknown vascular brain defects - aneurysm, etc.
10)family history of stroke