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. 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

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

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.

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]

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

More discussions about stroke

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