Stroke : Causes, Symptoms and Diagnosis
Neurology / / August 12, 2017
Stroke - is the sudden death of brain cells due to lack of oxygen.Stroke is usually defined as one of the following types:
- ischemic (caused by blockage of the arteries);
- hemorrhagic (caused by a break in the wall of the artery, and bleeding in the brain or around it).
Alternative names: transient ischemic attack.
Stroke can be caused by a blockage of blood flow of the brain (ischemic stroke) or the rupture of a sudden cerebral artery (hemorrhagic stroke).Brain cells require a constant flow of oxygen to stay healthy and function properly.Thus, the blood must be continuously fed to the brain in two main ways of the arterial system:
- carotid arteries - through both sides of the front of the neck;
- basic (basilar) arteries - at the base of the skull from the vertebral artery, which run along the spine and the back of the neck.
Circle of Willis (arterial circle of Willis) - a connection of multiple arteries to the bottom (side) of the brain.In the Circle of Willis branches
Blockage of blood flow to the brain, even for a short period of time can be catastrophic and cause brain damage or even death.
Ischemic stroke is by far the most common type of stroke and accounts for almost 90% of all strokes.Ischemia means "lack of oxygen to vital tissues."Ischemic stroke caused by blood clots, which are usually those types are:
- thromboembolic stroke, and atherosclerosis.These types of stroke usually occur when the artery that carries blood to the brain is blocked by a thrombus (blood clot), which results from arteriosclerosis (hardening of the arteries).The process leading to thrombotic stroke is complex and occurs over time: the walls of arteries thicken slowly, until the blood flow is not reduced, there is a stenosis.Because these processes continue, the blood flow is slowed.
- artery plaque-narrowed Laden, become susceptible to rupture.Formed thrombus, which breaks off and travels to the brain where an artery and blocks off oxygen to the brain.There stroke.
For ischemic stroke accepted to the following subtypes of the disease:
- cardioembolic stroke, and atrial fibrillation. embolic stroke is caused by a displaced thrombus that has passed through the blood vessels (embolism), has not yet penetrated the arteries.Cardioembolic strokes begin with blood clots in the heart and may be associated with different conditions:
- in many cases, blood clots initially formed as a result of cardiac arrhythmias (atrial fibrillation);
- embolus (embolus - any unbound intravascular substrate circulating in the bloodstream, is not found there in normal conditions, which can cause blockage of a blood vessel at a great distance from the place of occurrence) can also occur from blood clots that formed in place of artificial heart valves.
Patients with these disorders of the heart valves as mitral stenosis, are at increased risk of blood clots when they also have atrial fibrillation.
Emboli can also occur after a heart attack or due to heart failure.Emboli occasionally form of fat particles, tumor cells or air bubbles which travel through the bloodstream.
- Thrombotic strokes . Thrombotic strokes occur when a clot develops in the arteries of patients directly in the brain.Thrombotic strokes are less common than any type of embolic stroke.Thrombotic strokes typically occur at night, and their symptoms may develop more slowly than at embolism (sample pathological process caused by the presence and the circulation of blood or lymph does not occur in normal emboli conditions, often causing vascular occlusion followed by breach of localblood supply, often accompanied by sudden blockage of the vascular bed, clumps of calcium and parts of cholesterol plaques) stroke, which usually occurs quickly and suddenly.
- lacunarity stroke. Lacunary strokes (ischemic cerebral infarction, limited area of blood supply to one of the small perforating arteries, located in the deep parts of the cerebral hemispheres and brain stem in the process of organizing lacunar infarct formed cavity round shape -. Lacuna) are a series of very small ischemic strokes, embarrassing, weakness and emotional volatility.They constitute the majority of silent brain infarcts - probably as a result of chronic high blood pressure.This, in fact, thrombotic stroke subtypes.They can also sometimes serve as warning signs for a massive stroke.
Many older people are silent cerebral infarction - small episodes that do not cause any symptoms.They are found in almost half of elderly patients who are not on consciousness survey stroke.The presence of silent myocardial shows an increased risk of future stroke and dementia.Smokers and people with hypertension are at special risk.
- Transient ischemic attack (TIA) . Transient ischemic attack (TIA) - episode in which a person has similar stroke symptoms that usually last a few minutes and often - at least 1-2 hours.Transient ischemic attacks (PIM) embolism caused by tiny arteries in the brain.As a rule, they quickly disintegrate and dissolve, but to temporarily block blood flow to the brain.
TIAs do not cause lasting damage, but they are a warning sign that a true stroke may happen in the future, if not done enough to prevent it.By TIA should be taken very seriously and regarded as a stroke.About 10-15% of patients who have a TIA have a stroke within 3 months, with half of these attacks occurs within 48 hours after a TIA.
About 10% of strokes occur from sudden bleeding in the brain or around it.Despite the fact that hemorrhagic strokes are less common than ischemic, they tend to be more lethal.
Hemorrhagic strokes are divided over how and where they occur:
- Intracerebral Hemorrhagic strokes . These strokes are due to bleeding in the brain tissue.They are most often the result of high blood pressure and exert undue pressure on the walls of the arteries, atherosclerosis is already damaged.Patients with a heart attack, which had been given drugs to dissolve blood clots or blood-thinning drugs, have a slightly increased risk of this type of stroke;
- Subarachnoid Hemorrhagic attack. This type of stroke occurs when a blood vessel lying on the surface of the brain, the blood flows away into the subarachnoid space - between the brain and skull.They are usually caused by rupture of an aneurysm in a blood vessel bulge that creates a weakening in the wall of the artery;
- Arteriovenous malformation (AVM) - an abnormal connection between the arteries and veins.If there is in the brain, it may also cause a hemorrhagic stroke.
Causes and risk factors of stroke
Although age is a major risk factor, people who have suffered a stroke are likely to have more than one risk factor:
- Age. The greatest risk of stroke include older people, especially those who have high blood pressure, sedentary, overweight, smoke or have diabetes.Advanced age is also associated with higher rates of post-stroke dementia.Young people, however, are not insured.Many victims of stroke - younger than 65 years;
- Paul. In most age groups, except the group of elderly, stroke is more common in men than in women.However, stroke kills more women than men.This may partly be due to the fact that women tend to live longer than men, and stroke is more common in older people.Women account for about 6 cases of stroke by 10 deaths.For young women birth control pills and pregnancy may increase the risk of stroke;
- Race and ethnicity. all ethnic minority groups have a significantly higher risk of stroke and death from stroke than the basic nation.The difference in risk between all the groups decreases as the population ages.The largest differences occur in young people.Research shows that socio-economic factors also contribute to these differences;
- Family history. family history of stroke or TIA is the strongest risk factor for stroke.
- Smoking. People who smoke a pack a day have more than twice the risk of stroke than non-smokers.Smoking increases both hemorrhagic and ischemic stroke risk.The risk of stroke may remain elevated, so it is better to abandon it earlier for 14 years after quitting.
- Power. Malnutrition (saturated fats, excess sodium) may contribute to the development of heart disease, high blood pressure and obesity, which are the main risk factor for stroke.
- lack of physical activity. lack of regular physical exercise can increase the risk of obesity, diabetes and poor circulation of blood, which increase the risk of stroke.
- Abuse of alcohol and drugs. Abuse of alcohol, especially binge drinking, increases the risk of stroke.Abuse of drugs, particularly cocaine, or methamphetamine, is a key factor for stroke in young people.Anabolic steroids, which are attached to clothing and sports accessories, also increase the risk of stroke.
- Heart disease and blood vessels. Heart disease and stroke are closely linked for many reasons.People who have a bad heart and vascular conditions such as high blood pressure, high cholesterol, diabetes or peripheral arterial disease are at increased risk for other associated with these diseases.
- stroke. history of stroke or TIA significantly increases the risk for subsequent stroke.At 10 times the risk of stroke in people who have had, at least, only the TIA than those who have not had a TIA.
- suffering a heart attack. People who have had a heart attack are at increased risk of stroke.
- High blood pressure. High blood pressure (hypertension) contributes about 70% of all strokes.People with hypertension have up to 10 times higher than normal risk of stroke, depending on the severity of blood pressure and the presence of other risk factors.Hypertension is also a major cause of the so-called "silent cerebral infarcts" ( "mini-stroke" caused by blockages in the blood vessels of the brain), which can predict a massive stroke.Blood pressure control is very important for the prevention of stroke.
- Unhealthy cholesterol levels. High levels of total cholesterol increase the risk of atherosclerosis in the arteries, and heart disease.In atherosclerosis fatty deposits (plaques) of cholesterol build up in the arteries of the heart.
- Heart disease. Coronary heart disease, which is the end result of atherosclerosis, increases the risk of stroke.Anticlotting drugs used in the treatment of heart disease, blood clots are dissolved and may increase the risk of hemorrhagic stroke.
- Atrial fibrillation. This is the main risk factor for stroke associated with heart rhythm disorder in which the atria (the upper chambers in the heart) beat rapidly and irregularly.Blood stagnates - instead of being pumped out quickly, which increases the risk of blood clots, which are pulled out and sent to the brain.In 2-4% of patients with atrial fibrillation without a history of TIA or stroke in ischemic stroke occurs throughout the year.The risk is usually higher for those older than 75 years, as well as for people with heart failure or enlarged heart, coronary heart disease, a history of clots, diabetes, or a violation of a heart valve.
- Structural heart problems. Dilated cardiomyopathy (an enlarged heart), heart valve disorders and congenital heart disease - such as an oval opening in the chambers of the heart and atrial septal aneurysm (bulging of the heart chambers) are risk factors for stroke.
- atherosclerosis and peripheral arterial disease. heart Atherosclerosis is a major risk factor for stroke.It could lead to the fat in the carotid arteries of the neck, which can cause blood clots which block blood flow and oxygen to the brain.People with peripheral artery disease that occurs in atherosclerosis, constricts blood vessels in the legs and arms.Such people are at increased risk of disease of the carotid artery, and then stroke.
- Diabetes. Heart disease and stroke are the main causes of death in people with diabetes.Once high blood pressure, diabetes is ranked second as a primary risk factor for stroke.The risk is highest for adults with newly diagnosed type 2 diabetes and patients with diabetes who are younger than 55 years.Diabetes is a particularly strong risk factor for ischemic stroke, perhaps because there is a lot of accompanying risk factors - such as obesity and high blood pressure.Diabetes does not increase the risk of hemorrhagic stroke.
- Obesity and the metabolic syndrome. Obesity can increase the risk and ischemic and hemorrhagic stroke - regardless of other risk factors, which often coexist with obesity, including diabetes, high blood pressure and unhealthy cholesterol levels.Weight that is centered around the abdomen (called the "apple shape") is associated with particularly severe stroke, as is the case with heart disease, compared with the weight distributed around the hips (pear shape).Obesity is particularly dangerous when it is one of the components of the metabolic syndrome.This syndrome is diagnosed when there are three conditions: abdominal obesity, low HDL cholesterol, high triglycerides, high blood pressure and insulin resistance.Because metabolic syndrome - a pre-diabetic condition that is strongly associated with heart disease.People with this syndrome have an increased risk of stroke before the development of diabetes.
- Migraine. Studies show that migraine (severe headache) may be a risk factor for stroke in men and women, especially those under the age of 50 years.Overall, 3.2% of ischemic strokes occur in individuals with a history of migraine.However, in patients younger than 45 years - for about 15% of all strokes (and 30-60% of strokes in young women) are associated with a history of migraine, particularly migraine with aura (visual phenomenon, the pathology of perception for 10-30 minutes prior to an attack.).For young women with migraines other risk factors (high blood pressure, smoking and the use of estrogen-containing oral contraceptives, etc.) may increase the risk of stroke.
- Sickle-cell anemia. People with sickle cell disease are at increased risk of stroke at a young age..