Stroke

Definition

A stroke is the death of cells and loss of neurologic function in an area of brain tissue where blood circulation is blocked and brain cells are deprived of oxygen. The death of brain cells during a stroke results in a loss of abilities associated with that part of the brain, including possible loss of memory and muscle control. Interruption of blood flow in the brain can happen either as a result of a blood clot in a blood vessel that carries blood to the brain (ischemic stroke), a rupture of a weakened area (brain aneurysm) in an artery, or leakage of blood from a blood vessel in the brain.

Demographics

Each year, about 795,000 individuals in the United States experience a first stroke (600,000) or a recurrent stroke (185,000), and nearly 140,000 individuals die from the stroke. Individuals older than age 65 account for three-quarters of all strokes in the United States, but stroke can occur at any age. Men are affected slightly more than women (e.g., 126–214 vs. 122–198 in men and women over age 65, respectively, per 100,000 population). The World Health Organization (WHO) reports that 15 million individuals experience stroke worldwide; of those, 5 million die and 5 million are permanently disabled. Stroke is the third leading cause of death in the United States and the leading cause of adult long-term disability. Death rates from stroke are higher for African Americans across all age groups. Incidence of stroke is higher in southern states from East Texas to the southern Atlantic states. Risk is highest among those with high blood pressure. The risk of ischemic stroke in smokers is twice that of nonsmokers. Risk in individuals with atrial fibrillation is five times higher than in those without the irregular heartbeat.

Description

Two types of stroke can occur: ischemic stroke or hemorrhagic stroke. Ischemic stroke is the sudden loss of blood circulation in an area of the brain, resulting in a corresponding loss of neurologic function controlled by that part of the brain. In hemorrhagic stroke, bleeding occurs in the functional tissue of the brain (brain parenchyma) as a result of rupture of a weakened area of a major blood vessel (brain aneurysm) or the leakage of blood from smaller vessels damaged by chronic high blood pressure (hypertension). Although hemorrhagic stroke occurs less often (15% of all strokes) than ischemic stroke, it more often results in death (40% of all stroke deaths).

Ischemic stroke occurs when a blood vessel delivering blood to the brain is blocked by a blood clot or a fragment of hardened fatty deposits (atherosclerotic plaque) on the walls of an artery that supplies blood to the brain. This type of stroke accounts for about 87% of all strokes and can occur as an embolic stroke or a thrombotic stroke, depending on the source of vessel blockage. An embolic stroke occurs through blockage of a blood vessel by a blood clot (embolus) as a result of high blood pressure or an irregular heart beat called atrial fibrillation (Afib). About 15% of embolic strokes occur in individuals with Afib. Thromobotic strokes are caused by a blood clot that has formed inside one of the major arteries that supply blood to the brain. It occurs most often in individuals with high cholesterol and triglycerides and the accumulation of plaque on artery walls (atherosclerosis). A clot that forms on hardened plaque in arteries is called a thrombus.

Sometimes a serious warning of ischemic stroke occurs, and the signs can be missed if the individual or caregiver is not aware of what is happening. A transient ischemic attack (TIA) is not a stroke but is still considered an emergency requiring immediate medical attention. TIAs happen when a blood clot blocks an artery and interrupts blood flow to a specific part of the brain, producing transient stroke-like symptoms such as numbness in the face or limbs, confusion, difficulty speaking, vision problems, dizziness or difficulty maintaining balance, and sudden severe headache. The blocked artery is usually between the heart and the brain, often in the carotid artery in the neck, the vertebral arteries or within the brain itself. Although symptoms of stroke and TIA are often similar, the difference between a stroke and a TIA is that no permanent damage to the brain usually occurs as a result of TIA. However, clinical evidence from thousands of cases shows that strokes usually follow TIAs within one year, and sometimes as soon as 24 to 48 hours. A TIA is a critical indication that stroke is likely to occur, and physicians pay strict attention to TIAs to prevent or reduce blood clot formation and reduce the threat of stroke.

Risk factors

High blood pressure (hypertension), aging, high cholesterol and triglycerides, heart disease, carotid artery disease, previous TIA, diabetes, cigarette smoking, and excess alcohol consumption are the most common risk factors for stroke. Diabetes increases risk because of associated circulatory problems. Individuals with high blood pressure have a four to six times greater risk for stroke, and current smokers are at twice the risk of nonsmokers.

Causes and symptoms

The most frequent causes of stroke are high blood pressure, atrial fibrillation, atherosclerosis, carotid artery disease, and effects of smoking. Ischemic stroke, the blockage of a blood vessel delivering blood to the brain either by a blood clot or a fragment of atherosclerotic plaque, accounts for the majority (87%) of strokes. Results of research show that stroke is largely lifestyle-related and preventable. The cause in some individuals may be related to underlying chronic diseases such as diabetes, high blood pressure, and cardiovascular disease, which require regular management by the individual's primary care physician or specialist.

Any lifestyle factor that compromises the health of veins and arteries can also be considered a cause of stroke, including smoking, excess alcohol consumption, and consumption of unhealthy fats and sugars in the diet that lead to atherosclerosis. A characteristic of most of these health and lifestyle factors, along with normal aging, is damage to artery walls from chronic inflammation and the resultant narrowing of the arteries from the accumulation of atherosclerotic plaque on artery walls. In carotid artery disease, plaque builds up in either one or both of the carotid arteries on each side of the neck, narrowing them significantly (blockage can be between 50% and 70%), a condition called stenosis. The presence of narrowed arteries increases blood pressure and reduces blood circulation throughout the body, creating a potentially dangerous obstruction of blood flow that robs cells and organs of the oxygen they need to function properly (ischemia). Blockage of a major artery by accumulated plaque or a blood clot can prevent blood and oxygen from flowing to the brain, resulting in TIA or ischemic stroke.

The major symptoms of stroke are similar regardless of cause or type of stroke. Severity of symptoms, however, will differ depending on the degree of damage to brain tissue and brain cell function. The common symptoms of stroke include numbness in the face or limbs, confusion, difficulty speaking, blurring or other vision problems, dizziness or difficulty maintaining balance, and sudden severe headache. The presence or sudden onset of any of these symptoms could indicate TIA (mini-stroke) or an actual stroke. Any of these symptoms should be reported to a doctor or emergency service immediately.

To help get the fastest care for individuals who think they may be having a stroke, the National Stroke Association urges all adults to remember the acronym F-A-S-T: face drooping, arm weakness, speech difficulty, and time to call 911.

Diagnosis

Prompt recognition of TIA or stroke symptoms by the patient, family member, or caregiver will lead to faster diagnosis and treatment and less damage to the brain. Immediate examination by a physician or paramedic is essential.

Examination

The physician will examine the patient for signs of weakness in the face, arms, and legs, and note any altered speech or signs of confusion. Immediate monitoring of vital signs such as blood pressure and heart rate will begin as well as listening with a stethoscope for whooshing sounds in the neck that may indicate atherosclerosis in the carotid arteries. The eyes may be examined, looking for cholesterol crystals or clots in the blood vessels behind the eyes. Family history of stroke may be noted. The individual's recent history of symptoms and current and prior diseases or conditions, including prior TIAs, will be reviewed as quickly as possible.

Tests

Diagnostic laboratory tests will include a complete blood count, platelet count, and coagulation tests (prothrombin time, partial thromboplastin time) to determine the likelihood of clotting abnormalities and clot formation. Serum electrolytes (sodium, potassium, chloride) will be done to evaluate the possible presence of vascular or heart abnormalities, and blood glucose will be done to evaluate possible blood glucose abnormalities, which can produce symptoms similar to those of TIA or stroke.

Procedures

An electrocardiogram (ECG) will be done to evaluate heart function. Doppler ultrasound, also called carotid ultrasound, may be used to examine the carotid arteries for atherosclerosis and obstruction that may have caused the stroke. Computed tomography of the head (brain CT) may be done to determine if brain hemorrhage has occurred or a tumor may be present, which could mimic TIA or stroke; prior TIA or stroke can also be identified with CT scans. Magnetic resonance imaging (MRI) may also be performed to examine brain tissue more closely for specific damage; MRI is considered the most accurate imaging technique for evaluating the extent of stroke damage.

A cerebral angiogram may be needed to view the arteries of the neck and brain in more detail. This imaging exam involves passing a thin, flexible catheter through a small incision in the groin and guiding it up into the carotid or vertebral arteries. Injecting dye into these blood vessels allows the physician to view the inside of the arteries via x-ray images on a monitor.

A transesophageal echocardiogram may also be done to provide ultrasound images of the heart and its blood vessels. In this ultrasound exam, a tiny ultrasound transducer is passed into the esophagus, the tube through which food travels to the stomach. The transducer is lowered into the esophagus until it is directly behind the heart where it will capture images of the heart and coronary arteries and display them on a monitor. This will allow the physician to detect any blood clots in the coronary arteries.

Treatment

Ischemic stroke and hemorrhagic stroke are treated differently because the former must restore blood flow to the brain and the latter must stop hemorrhagic bleeding in the brain. Treatment for both types of stroke will seek to prevent recurrent stroke and will require a period of intensive rehabilitation after the emergent treatment.

Ischemic stroke

The goal of treatment for ischemic stroke is to restore blood flow to the brain and prevent new clot formation. Immediate treatment, ideally within 4.5 hours at most, will focus on dissolving blood clots or preventing additional clot formation. Drug therapy with antithrombotic drugs that break up clots will typically be given intravenously and will include tissue-type plasminogen activator (tPA), including alteplase (Activase, Actilyse) injected into a vein within three hours of an ischemic stroke. Some drugs prevent clot formation by reducing platelet aggregation, a mechanism involved in clot formation. Among the many antiplatelet drugs are clopidogrel (Plavix), abciximab (ReoPro), and dipyridamole (Persantine). Anticoagulant agents may be used such as warfarin (Coumadin, Jantoven) or heparin-based drugs (Certoparin, Reviparin, Danaparoid). The types of drugs and their dosage are selected based on the overall health status of the individual and the presence of any concomitant chronic disease. Individuals are monitored extremely closely while receiving antiplatelet or anticoagulant drug therapy. Blood will be drawn frequently to measure coagulation processes and conditions of the blood that could lead to hemorrhage in some individuals. Most stroke patients who receive antiplatelet and anticoagulant drugs in the hospital will continue to take one of the drugs after discharge, perhaps at a lower dosage.

Another procedure that may be used to open the carotid arteries is angioplasty and stent insertion. It is performed following the same procedure as carotid angioplasty, accessing the carotid arteries through the femoral artery in the groin and navigating to the narrowed arteries to place a balloon inside. When the balloon is inflated, the artery expands and a synthetic metal stent is inserted to support the opened artery and improve blood flow to the brain.

Hemorrhagic stroke

In hemorrhagic stroke, the goal is to control the bleeding and reduce pressure within the brain. Individuals who already take antithrombotic drugs such as clopidogrel or warfarin to prevent blood clots will need treatment to counteract the effects of these so-called blood thinners. Other drugs may be given to lower blood pressure, prevent spasm in the blood vessels (vasospasm) or seizures.

Surgery may be performed to remove the accumulated blood from the brain hemorrhage and relieve pressure on the brain. Blood vessel abnormalities such as an aneurysm or arteriovenous malformation (AVM) that caused the hemorrhagic stroke may also need to be repaired. Surgical treatment of an aneurysm may require compressing the base of the weakened blood vessel with a tiny clamp to stop blood flow to it and keep it from bursting. An aneurysm can also be fitted with tiny coils that will block blood flow and cause the hemorrhagic blood to clot (endovascular embolization). An AVM can be removed from the brain to prevent rupture and lower the risk of a hemorrhagic stroke. This surgical procedure cannot be done, however, if brain function would be markedly affected or the AVM is too large or too deep in the brain.

Stereotactic radiosurgery is an advanced, minimally invasive treatment that may be used instead of other surgeries to repair AVM. It is performed using multiple beams of highly focused radiation to treat the malformed area directly, reducing the risk of hemorrhagic stroke.

Stroke rehabilitation

Rehabilitation is necessary after emergent treatment of stroke and focuses on recovering as much function as possible. If the stroke affected the right side of the brain, movement and sensations on the left side of the body will likely be affected. If stroke occurred on the left side of the brain, the right side of the body is affected, and speech and language disorders may also develop. Rigorous rehabilitation programs are designed for each individual based on age, overall health, and the degree of disability caused by the stroke. Sometimes rehabilitation begins even before the individual leaves the hospital and then continues in the rehab section of the hospital or a separate rehab facility. Usually a neurologist trained in brain conditions will direct the rehab program, and care will be given by a doctor trained in rehab (physiatrist), specially trained rehab nurses, a dietitian, physical and occupational therapists, speech pathologist (treating speech and swallowing difficulties), social worker, case manager, psychologist or psychiatrist, and a chaplain. The various rehab services will restore function as much as possible during the intensive program and will provide additional at-home services such as meal planning and physical activity guidance as needed until maximum rehabilitation is accomplished.

KEY TERMS
Arteriovenous malformation—
A tangle of abnormal veins and arteries in the brain that may cause headaches, seizures, or stroke.
Atherosclerosis—
Hardening and narrowing of the arteries due to the accumulation of fatty deposits and cellular debris (plaque) on artery walls.
Embolism—
Obstruction of an artery by a blood clot or air bubble.
Endovascular embolization—
An invasive surgical procedure performed to treat abnormal blood vessels in the brain by blocking blood vessels and blood flow to a specific area.
Parenchyma—
Functional tissue (parenchymal tissue) in the brain made up of the two types of brain cells, neurons and glial cells.
Plaque—
Accumulation of fatty deposits, fibrous material, cellular debris, and minerals on damaged areas of the tissue lining the arteries that narrows the arteries and increases blood pressure. Plaque is the underlying cause of atherosclerosis.
Thrombus—
A blood clot formed within the system of veins and arteries in the body that blocks the flow of blood.

Nutrition/dietetic concerns

Lifestyle changes to reduce risk factors for stroke will necessarily include diet. A review of the literature on stroke prevention found that dietary modification reduces the risk for both ischemic and hemorrhagic stroke. The American Stroke Association states that a heart-healthy diet is also good for the brain. To help prevent stroke, the organization advises:

A vegetarian diet has been shown to be associated with lower blood pressure, which is a risk factor for TIA and stroke. The DASH diet, which has also been shown to reduce blood pressure and is described in Dietary Approaches to Stop Hypertension, is recommended by the National Institutes of Health (NIH), the American Heart Association, and many physicians and cardiologists. It is considered just as beneficial in preventing heart disease and stroke as it is in reducing blood pressure, because salt, fat, and sugar content is far below the national average. The DASH diet consists of fruits, vegetables, low-fat dairy, whole grains, poultry, fish, and nuts.

The 2015–2020 Dietary Guidelines for Americans, which was introduced in 2015 by the United States Department of Agriculture (USDA) and the Department of Health and Human Services, stresses overall health and prevention of stroke and heart attack through diet and lifestyle choices. Healthy eating patterns are described as including a variety of vegetables from all the subgroups (dark green leafy, red and orange, legumes, and starchy); whole fruits; grains, at least half are whole grains; fat-free or low-fat dairy (milk, yogurt, cheeses) and soy beverages; and a variety of proteins, including seafood, lean meats, poultry; eggs, legumes, nuts, seeds, and soy products; and oils such as olive oil and canola oil, but not saturated fats and trans fats. Smoking and alcohol consumptions are discouraged, and physical activity must accompany any dietary plan designed to promote health. Detailed information can be found at http://www.dietaryguidelines.gov .

QUESTIONS TO ASK YOUR DOCTOR

Prognosis

The effects of a stroke depend on where the stroke occurred in the brain, which functions were affected, and how much damage was done to brain tissue. One-third of patients will die after stroke. Some individuals recover completely from strokes, although two-thirds of individuals have some level of disability. Those who have had a mild or small stroke may have only minor problems such as temporary weakness in an arm or a leg that can usually be corrected with physical therapy; other individuals who have larger strokes may be paralyzed permanently on one side of the body and lose their ability to speak. Hemorrhagic stroke is more likely to lead to death than ischemic stroke.

Prevention

See also African American diet ; Hypertension .

Resources

BOOKS

Burkman, Kip. The Stroke Recovery Book: A Guide to Patients and Families. 2nd ed. Chicago: Addicus, 2012.

Levine, Peter G. Stronger after Stroke. 3rd ed. New York: Demos Health, 2018.

PERIODICALS

Alderazi, Yazan J., and James C. Grotta. “Acute Antithrombotic Treatment of Ischemic Stroke.” Current Vascular Pharmacology 12, no. 3 (May 2014): 353–64.

Iacoviello, L., M. Bonaccio, G. Cairella, et al. “Diet and Primary Prevention of Stroke: Systematic Review and Recommendation by the Ad Hoc Working Group of the Italian Society of Human Nutrition.” Nutrition, Metabolism, and Cardiovascular Diseases 28, no. 4 (April 2018): 309–34.

Leigh, Richard, and John W. Krakauer. “MRI-Guided Selection of Patients for Treatment of Acute Ischemic Stroke.” Current Opinion in Neurology 27, no. 4 (August 2014): 425–33.

Yu, Edward, and Frank B. Hu. “Dairy Products, Dairy Fatty Acids, and the Prevention of Cardiometabolic Disease: A Review of Recent Evidence.” Current Artherosclerosis Reports 20, no. 5 (March 2018): 24–32.

Wang, X., S. You, S. Sato, et al. “Current Status of Intravenous Tissue Plasminogen Activator Dosage for Acute Ischemic Stroke: An Updated Systematic Review.” Stroke and Vascular Neurology 3, no. 1 (March 2018): 28–33.

WEBSITES

American Stroke Association. “Nutrition Tips for Stroke Survivors.” American Heart Association. (accessed May 22, 2018).

Jauch, Edward C. “Ischemic Stroke.” Medscape. https://emedicine.medscape.com/article/1916852-overview (accessed May 22, 2018).

Mayo Clinic Staff. “Stroke: Diagnosis and Treatment.” Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/stroke/diagnosis-treatment/drc-20350119 (accessed May 22, 2018).

National Stroke Association. “Diet and Nutrition.” Stroke.org . http://www.stroke.org/we-can-help/stroke-survivors/living-stroke/rehabilitation/diet-and-nutrition (accessed April 2, 2018).

ORGANIZATIONS

Academy of Nutrition and Dietetics, 120 South Riverside Plz., Ste. 2000, Chicago, IL, 60606-6995, (312) 899-0040, (800) 877-1600, amacmunn@eatright.org, http://www.eatright.org .

American Heart Association, 7272 Greenville Ave., Dallas, TX, 75231, (888) 242-8883, help@onlineaha.org, https://www.onlineaha.org .

American Stroke Foundation, 6405 Metcalf Ave., Ste. 214, Overland Park, KS, 66202, (913) 649-1776, http://www.americanstroke.org .

National Stroke Association, 9707 East Easter Lane, Ste. B, Centennial, CO, 80112, (800) 787-6537, info@stroke.org, http://www.stroke.org .

L. Lee Culvert

  This information is not a tool for self-diagnosis or a substitute for professional care.