Cerebrovascular Accident

Definition

Cerebrovascular accident (CVA) is the medical term for what is commonly termed a stroke. It refers to the injury to the brain that occurs when flow of blood to brain tissue is interrupted by a clogged or ruptured artery, causing brain tissue to die because of lack of nutrients and oxygen.

Description

The severity associated with cerebrovascular accident can best be demonstrated by the following facts:

• CVA is the leading cause of adult disability in the world.
• Worldwide, one-quarter of all strokes are fatal.
• Stroke is the third leading cause of death in the United States and the leading cause of disability.
• It is estimated that four of every five families in the United States will be affected by stroke in their lifetime.
• More than half a million people in the United States experience a new or recurrent stroke each year.
• 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 $43 billion per year in direct costs and loss of productivity.
• Two-thirds of strokes occur in people over the age of 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.
• The incidence of strokes among people ages 30 to 60 is less than 1%. This figure triples by the age of 80.
• The rate of occurrence for strokes in the United States fell by 15.52% between 1988 and 1998. But the number of deaths from stroke actually rose by 5%.

Causes and symptoms

Arterial blood carries oxygen and nutrients 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. There are two forms of stroke, ischemic, which is caused by a blocked blood vessel that supplies blood to the brain, and hemorrhagic, which is bleeding into or around the brain.

The most common type of stroke is ischemic, which refers to the loss of oxygen and nutrients for brain cells that occurs 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, also termed cerebral embolism.

Thrombotic strokes are by far the more prevalent of ischemic strokes, 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 occurrence of the symptoms of a thrombotic stroke are much more gradual and less dramatic than other strokes due to the slow, ongoing process that produces it.

Transient ischemic attacks (TIAs) are one form of thrombotic stroke, and usually the least serious. TIAs represent the occlusion of a very small artery, or arteriole. 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, consequently, an insufficient amount of oxygen and nutrients.

Embolic strokes are usually a more spectacular, emergency event. They take place when the heart's rhythm is changed for a number of reasons, and blood clot formation takes place. Such a 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 the blood clot 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. Normally, these blockages occur in the brain itself, as 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 cerebrovascular accidents are termed hemorrhagic strokes, and are generally classified as subarachnoid hemorrhage or intracerebral hemorrhage, depending upon the location of the hemorrhage. Hemorrhagic strokes occur when an artery to the brain has a weakness and balloons outward, producing an aneurysm. Such an aneurysm often ruptures 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. However, which symptoms appear depends upon which portion of the brain is cut off from its supply of oxygen and nourishment. The brain is divided into left and right hemispheres, which control bodily movement on opposing sides of the body. For example, the left hemisphere of the brain is responsible for both motor control of the right side of the body and its sensory discrimination, just as the right hemisphere is responsible for body movements and feeling on the left side. 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 affect the person's ability to speak.

Besides age, high blood pressure (hypertension) is one of the foremost causes of thrombotic stroke. Heart disease, obesity, diabetes, smoking, oral contraceptives in women, polycythemia (an increased number of red blood cells), and sleep apnea are also risk factors for thrombotic stroke, as is a diet high in cholesterol-producing, or fatty, foods.

The risk factors for hemorrhagic stroke include high blood pressure that can, over a period of time, cause the ballooning out of arteries known as aneurysm, and also causes the hereditary malformation that produces defective and weakened veins and arteries. Substance abuse is another major cause of hemorrhagic stroke. Cocaine, stimulants such as amphetamine drugs, and chronic alcoholism can cause a weakening of blood vessels that can result in hemorrhagic stroke.

The symptoms of stroke 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, mental confusion, vertigo, vision problems, difficulty speaking and communicating, including slurring of words (aphasia ), and weakness or paralysis of one side of the body (hemiplegia) are all symptoms of stroke that are frequently observed. 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 been damaged and its location in the brain.

Diagnosis

Normally, initial diagnosis will be made based upon observation by health care professionals, and usually a complete neurological examination. 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 associated with ischemic activity within the body. Electrocardiogram (EKG), angiography, and lumbar puncture are all used to rule out any other possible causes of the symptoms.

Treatment

Emergency treatment

Strokes are always considered a medical emergency, and every minute is important in initiating treatment. With the possible exception of TIAs, all other types of stroke are a life-threatening event. A severe CVA that results in coma or unconsciousness will require medical monitoring and support, including oxygen and possibly intubation to ensure an adequate airway and to facilitate the patient's breathing. Providing fluids that the person may not be able to take by mouth due to swallowing difficulties may also be necessary.

Emergency treatment of stroke caused by a blood clot is directed at dissolving the clot. This thrombolytic therapy is currently performed most often with tissue plasminogen activator, or t-PA. As t-PA must be administered within three hours of the stroke event, people that awaken with stroke symptoms are usually considered beyond the time limit for t-PA therapy. 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 within three hours of the stroke were one-third more likely to be left with no permanent residual difficulty.

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, in some cases, with aspirin or other anti-clotting agents.

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

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 an incision through the skull to relieve the pressure. 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 bleeding. 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.

Longer term or rehabilitative treatment

Rehabilitation refers to a comprehensive program designed to regain function as much as possible and to compensate for permanent losses. It 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. Right brain strokes may affect spatial perception, and patients with right brain strokes may also deny their illness, neglect the affected side of their body, and behave impulsively.

Much of the needed care in the days and weeks following a stroke will be to prevent further damage than what has already occurred. The severely ill stroke patient will require frequent repositioning to prevent complications such as pneumonia and venous or pulmonary embolism. Deep venous thrombosis, in which a clot forms within a limb immobilized by paralysis, is one of the most common medical complications following stroke. Clots that break free often become lodged in an artery feeding the lungs. This type of pulmonary embolism often causes 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 (dysphasia), and allow food to enter the lower airway. This may lead to aspiration pneumonia, another common cause of death shortly after a stroke. Because of the difficulty 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 either nasogastric, a thin tube that is inserted through the nose, into the esophagus, and then into the stomach, or a gastric one, which is a wider-lumen tube surgically implanted into the stomach. Less extreme dysphasia may be treated with retraining exercises and temporary use of pureed foods.

Other possible medical complications can include urinary tract infections, pressure ulcers, and falls. Urinary catheters are often inserted into the bladder to prevent the skin damage that can be caused by incontinence, but the presence of a catheter may also contribute to infections and loss of bladder tone. Bladder training, which consists of regular interval exercises to regain bladder tone, should begin as soon as possible. Frequent repositioning and good skin care will prevent the development of pressure ulcers, or decubitus ulcers.

Paralysis requires prevention of contractures (the tightening up of paralyzed limbs). Contractures and spasticity may be treated with a combination of stretching and splinting and, besides exercise, may include the use of supportive braces for arms or hands, or using footboards or wearing sneakers when in bed to prevent foot drop.

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 dysphasia is a problem, a nutritionist can advise alternative meals that provide adequate nutrition.

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. Depression occurs in an estimated 30-60% of all stroke patients, which is not surprising as they are typically dealing with a tremendous loss of abilities and independence. As such depression will impact upon the person's rehabilitation and recovery, it needs to be addressed, and may require the services of a psychiatrist and psychiatric nurse or mental health assistant. Antidepressants and psychotherapy may be used in combination.

Prognosis

The National Institute of Neurological Disorders and Stroke reports that 25% of people who suffer a stroke recover completely, while 20% die within three months after the stroke. Stroke is fatal for nearly twice as many people of African-American heritage as it is for European-Americans. Of the remaining 55% of people who have strokes, 5% will require long-term (nursing home) care. For the rest, rehabilitative and restorative services will be necessary in order for them to regain as much of their former capabilities as possible.

Brain tissue that dies in a stroke cannot regenerate, and stroke survivors may be left with significant deficits. It has been estimated that the most common irreversible damage from stroke is that done to intellectual functions. But as is increasingly shown, emergency treatment and comprehensive rehabilitation can significantly improve both survival and recovery. In some cases, many functions that are lost due to stroke may be performed by other brain regions after a training period, or compensatory actions may be developed to replace lost abilities.

Health care team roles

Rehabilitation is provided by a team of medical professionals, including the services of a neurologist, a physician who specializes in rehabilitation medicine, nurses to both provide care and assist the physician in coordinating the necessary services the stroke patient needs, a physical therapist, an occupational therapist, a speech-language pathologist, a nutritionist, 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.

Several different physicians may be involved, at one time or another, in the care of the stroke patient:

• A primary care physician (PCP) provides basic medical care to patients.
• A physical medicine and rehabilitation specialist assists patients to recover from or overcome disability or impairment. Often physical therapists work under their supervision.
• A neurologist specializes in disease conditions of the nervous system, and may be consulted to evaluate the extent of actual damage from a stroke.
• In the case of cerebral hemorrhage, a neurosurgeon, a specialist in both neurology and the surgical correction of nervous system damage, may be called upon to do surgery.
• Psychiatrists are licensed medical doctors that are often called upon to evaluate cognitive ability and to treat depression.
• Registered nurses (RNs) or licensed practical nurses (LPNs) are the health care provider that deal most often with the person who has had a CVA. Their duties include taking vital signs and monitoring the patient for complications of the stroke. They also educate the patient and family about the nature of strokes, the importance of preventing contractures and maintaining good range of motion, and about adequate nutrition and fluid intake.
• Physical therapists work with disabled stroke patients to maintain and restore range of motion and strength in affected limbs, and to maximize mobility in walking, wheelchair use, and transferring (for instance, from wheelchair to toilet or from standing to sitting). The physical therapist advises on mobility aids such as wheelchairs, braces, and canes.
• A social worker may help coordinate services and ease the transition out of the hospital back into the home, or into an extended care facility, if necessary. Social workers may help counsel the patient and family during the difficult rehabilitation period.
• Nutritionists educate stroke patients about eating nutritious foods and following through on a therapeutic diet as ordered by the physician.
• Occupational therapists help stroke patients to relearn muscular control and coordination in order to carry out normal activities of daily living such as bathing, dressing, and preparing meals.
• Speech-language therapists assist stroke patients who have damage to the speech center in the brain.
• Clinical laboratory scientists draw blood samples or test urine or sputum specimens that are ordered by the physician.
• Radiologic technologists take x rays, CT scans, and MRIs to visualize and monitor the brain or other affected organs after a stroke.

All health care team members are aware that the person who has suffered a stroke and the family members who may care for the person at home will need to learn entirely new sets of skills and adaptations. Both the patient and family often experience stress, anxiety, and depression. They may need to learn about physical and mental symptoms that are common in stroke patients, and the family may even need to learn how to deliver necessary care. Support groups can provide an important source of information, advice, and comfort for stroke patients and for caregivers. For the stroke patient, joining a support group can be one of the most important steps in the rehabilitation process.

Prevention

An important facet of rehabilitation is preventing the recurrence of stroke. Control of blood pressure is the single most important factor in the prevention of strokes. People should regularly have their blood pressure checked, and if it is found to be 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.

Diet, including the reduction of sodium (salt) intake, exercise, and weight loss, if necessary, are all non-drug treatments for lowering blood pressure. Other natural remedies include the consumption of artichoke, which lowers the fat content of the blood, garlic, now believed to lower cholesterol and blood pressure as well as reduce blood's clotting ability, and ginkgo, which improves circulation and strengthens arteries and veins. The use of folic acid, lecithin, and vitamins B₆, B₁₂, C, and E is recommended as supportive measures in reducing blood pressure.

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

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

• Beta blockers are used to reduce the force and speed of the heart-beat.
• Vasodilators are used to 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 bloodstream.

KEY TERMS

Aneurysm— A pouch-like bulging of a blood vessel.

Angiography— The procedure that enables blood vessels to be seen on film after the vessels have been filled with a substance that shows up opaque on x rays.

Arrhythmia— An abnormality of the rhythm or rate of the heartbeat.

Arteriole— The tiny extensions that arteries eventually break down into as they circulate blood.

Artery— Pliable, three-layered vessels that carry the blood away from the heart.

Atherosclerosis— Disease of the arterial wall in which the inner layer thickens, causing narrowing of the channel and thus impairing blood flow.

Computerized tomography (CT) scan— The diagnostic technique in which the combined use of a computer and x rays passed through the body at different angles produces clear, cross-sectional images of the tissue being examined.

Ischemic— Insufficient blood supply to a specific organ or tissue.

Lumbar puncture— A procedure in which a hollow needle is inserted into the lower part of the spinal canal to withdraw cerebrospinal fluid (the clear liquid which surrounds the brain and spinal cord), or to inject drugs or other substances.

Magnetic resonance imaging (MRI)— The diagnostic technique that provides high quality cross-sectional images of organs or structures within the body without x rays or other radiation.

Myocardial infarction— Heart attack; sudden death of part of the heart muscle characterized in most cases by severe, unremitting chest pain.

Polycythemia— Increased number of red cells in the blood.

Sleep apnea— A condition in which a person experiences episodes of cessation of breathing lasting 10 seconds or longer during sleep.

Thrombotic— Pertaining to a blood clot formed within an intact blood vessel as opposed to a clot formed to seal the wall of a blood vessel after an injury.

Transient ischemic attack (TIA)— Occlusion of smaller blood vessels to the brain that can produce stroke-like symptoms for anywhere from a few minutes to 24 hours, but leaves no permanent damage.

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.

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

ORGANIZATIONS

American Stroke Association. 〈http://www.strokeassociation.org〉.

National Institute of Neurological Disorders and Stroke, U.S. Department of Health and Human Services, National Institutes of Health. 〈http://www.ninds.nih.gov〉.

American Heart Association. 〈http://www.americanheart.org〉.