Symptoms of stroke occur suddenly, and in clusters Table 01. The most common symptoms of stroke include weakness or paralysis, often on just one side of the body; sudden, severe numbness or loss of sensation; sudden difficulty seeing in one or both eyes; confusion or difficulty speaking or understanding speech (words may be slurred, or you may be unable to speak); a sudden, severe headache with no known cause; difficulty walking; and dizziness or loss of balance or coordination. The symptoms of patients with hemorrhagic stroke are likely to reflect extreme pressure on the brain, and may include sudden, severe headache, nausea, vomiting, seizures, stupor, or coma.
Table 1. Symptoms of Stroke
Sudden weakness or paralysis, especially on one side of the body Sudden numbness or loss of sensation Sudden difficulty speaking or understanding speech Sudden trouble seeing in one or both eyes Sudden loss of balance or coordination; dizziness; difficulty walking Sudden, severe headache with no known cause Sudden nausea and vomiting Brief loss of consciousness or period of confusion, fainting, convulsions, or coma
The numbness or paralysis associated with stroke often affects just one side of the face, or one leg or arm. This unilateral distribution happens because strokes usually damage only one side of the brain. Symptoms tend to appear on the side of the body opposite the affected area of the brain.
A transient ischemic attack (TIA) starts with the same symptoms as those of stroke. With TIA, however, the symptoms may go away within 10 to 20 minutes, and rarely last longer than an hour. Since it is impossible to determine at the onset whether symptoms will persist or quickly subside, you should always seek immediate medical treatment.
As TIAs tend to recur, you may have several attacks in a day, or over several days. However, you may also have symptom–free periods for several years.
High blood pressure is the most significant risk factor for stroke. If you have high blood pressure, your risk of stroke increases four– to sixfold. An estimated 40% to 90% of stroke patients are diagnosed with high blood pressure before their attack. High blood pressure can cause the arteries to narrow so that less blood reaches the brain. It can also make the arteries thick and stiff, conditions that encourage a buildup of fat and cholesterol and can interfere with the flow of blood to the brain.
Heart disease is a risk factor for stroke. Although several types of heart disease are associated with stroke, atrial fibrillation carries the greatest risk. Overall, an estimated 20% of ischemic strokes are due to brain embolism from the heart. Atrial fibrillation is defined as irregular beating of the upper left chamber of the heart (left atrium). During fibrillation, the left atrium beats up to four times faster than the rest of the heart, causing irregular bloodflow and the potential for blood clots to form. If a clot moves from the heart to the brain, it can cause a stroke. About 15% of stroke patients have atrial fibrillation before their attack; among patients over the age of 80, one in four strokes is caused by atrial fibrillation.
Disorders of the heart valves or heart muscle can also increase your risk for stroke. Myocardial infarction (heart attack), valve diseases such as mitral valve stenosis, and prosthetic heart valves can increase your risk for stroke. Two heart disorders that can potentially increase stroke risk are patent foramen ovale (PFO) and atrial septal aneurysm (ASA). PFO is a hole in the heart wall that separates the two upper chambers. Blood clots may pass through this hole, enter the arteries, and circulate to the brain. ASA, which is present from birth, is a bulging of the heart wall into one of the chambers. ASA and PFO often occur together, increasing the risk for stroke.
Two other heart conditions implicated in stroke risk are left ventricular hypertrophy and left atrial enlargement. Left ventricular hypertrophy means a thickening of the wall of the left ventricle. If you have left atrial enlargement, your left atrium is larger than normal. It is unclear precisely how these two malformations affect the risk of stroke.
Having a history of TIA or stroke increases your risk of having another stroke. About one in five individuals who have had a TIA will have a stroke within a year. Having had a previous stroke also increases your risk of having another one—about one in four patients who recover from a stroke will have another within five years. However, making lifestyle adjustments such as giving up smoking or adopting a low–fat diet may reduce your risk.
Cardiac surgery can increase your stroke risk by about 1%. During heart surgery, a plaque can become dislodged and move through the blood to the arteries in the neck and head, causing a blockage that can precipitate a stroke.
Having diabetes increases your risk for stroke about threefold. There are two ways in which having diabetes affects your risk for stroke. First, high blood sugar levels damage your blood vessels by making the walls thicker and less elastic, which in turn makes it more difficult for blood to circulate. Second, people with diabetes tend to have high levels of fat in their blood that clog the arteries. Keeping your blood sugar and fat levels under control helps to reduce your risk for stroke.
Your blood cholesterol levels play a major role in your stroke risk. The risk of stroke and heart disease stems mainly from the cholesterol in the foods you eat. Eating a diet high in saturated fat and cholesterol increases the amount of cholesterol in your body, and can cause hardening and thickening of the arteries. Foods such as meat, eggs, and dairy products are primary sources of cholesterol and fat.
Excessive cholesterol builds up in your arteries, where it is converted into plaque, blocks the blood vessels, and helps form blood clots that can lead to stroke.
Smoking nearly doubles the risk for ischemic stroke. Cigarette smoking is a strong risk factor for stroke, especially among younger adults. Smoking encourages hardening of the arteries, and promotes growth of blood clots that can cause stroke.
Heavy alcohol use increases your blood pressure, and therefore also your risk of having either an ischemic or hemorrhagic stroke. However, several scientific studies have suggested that moderate daily alcohol consumption may actually decrease your risk of ischemic stroke, apparently by decreasing blood clotting. Discuss your alcohol consumption with your doctor to determine what amount of alcohol, if any, you can tolerate with your condition.
Using illicit drugs can be associated with strokes.
Cocaine and crack cocaine may cause stroke because they suddenly raise the blood pressure and narrow the blood vessels in the brain, reducing blood flow. The amount of narrowing increases with the frequency of drug use. Cocaine can also cause heart rhythm disorders and rapid heart rate, which may cause blood clots to form.Other drugs that have been associated with stroke risk include amphetamines and heroin.
Stroke can occur as a complication of syphilis. A syphilitic infection may cause blockage of the arteries in the brain, causing decreased blood flow and damage to brain tissue. Successful treatment of syphilis reduces the risk of stroke.
Certain inherited and congenital conditions also increase the risk of stroke. Fibromuscular dysplasia (FMD) is an arterial disorder that can cause stroke, primarily among women over 50. FMD may cause stroke if it affects the carotid arteries that supply blood to the brain, or arteries within the brain itself. A rare genetic disease called cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is also a risk factor for stroke and dementia.
Stroke seems to run in some families, even when specific inherited diseases such as FMD are not present. This genetic link may occur because many of the conditions that put a person at risk for stroke such as diabetes or high blood pressure— are heritable disorders. Habits that may be reinforced in families, such as smoking or eating a high–fat diet, also can influence risk for stroke.
Although a stroke can occur at any age, the risk is highest for older individuals. For every decade after age 55, the risk of stroke doubles: an estimated two–thirds of strokes occur in people over age 65. People in this age group also have a higher risk of dying from stroke than younger individuals.
Although the risk for men is 1.25 times higher than for women, women are more likely to die from stroke.As women generally live longer than men, they are usually older when they have their first stroke, and are more likely to die as a result. Men tend to be younger and in somewhat better overall health when they have a stroke, and therefore are more likely to survive.
The incidence of stroke and the death rate among stroke sufferers are approximately twice as high among African–Americans than in white Americans. This racial discrepancy may be related to a higher rate of risk factors such as smoking or high blood pressure among African–Americans. African–Americans also have a higher incidence of genetic diseases such as diabetes and sickle cell anemia, which also increases their likelihood of having a stroke.
The Southeast has the highest stroke mortality rate in the US, and is sometimes called the "Stroke Belt." Three states within this region—Georgia, North Carolina, and South Carolina—have mortality rates that are approximately twice as high as that of the US as a whole. While the reasons for these differences in stroke incidence and mortality are unclear, possible factors include higher rates of cigarette smoking and a regional preference for salty, high–fat foods, both of which can contribute to hypertension.
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