Causes of a stroke
introduction
A stroke is a life-threatening illness which, despite the best therapy, can in many cases lead to serious consequential damage or even death. Thus, it makes sense to better understand the causes and risk factors of the disease in order to reduce the likelihood of a stroke through early prevention.
The different causes of a stroke
80% of strokes are caused by acute circulatory disorders in the brain, which leads to an insufficient supply of the nerve cells with oxygen and thus ultimately to cell death. The size of the affected brain area depends largely on the amount and size of the affected vessels.The circulatory disorders are based either on an increasing narrowing of blood vessels due to deposits, the so-called arteriosclerosis, or on a blockage of the vessel due to a blood clot, also called a thrombus.
Another 10-15% of strokes are caused by bleeding into the brain tissue. Such bleeding occurs mainly with high blood pressure or brain aneurysms and is difficult to treat. Here, too, the nerve cells are insufficiently supplied with oxygen and nutrients, and the cells are directly damaged by the increased intracranial pressure.
The remaining 2-5% of strokes can be traced back to so-called subarachnoid hemorrhages, i.e. bleeding into the space between the brain and the soft meninges. All of these possible causes are associated with risk factors that can massively promote their development.
Hardening of the arteries
Calcification of the arteries, also known as arteriosclerosis, is one of the most important risk factors for the development of strokes. The risk of such calcification, however, is strongly dependent on the location. In the case of generalized, i.e. everywhere occurring, hardening of the arteries, there is the main risk that deposits (plaques) will loosen from the calcified wall, get into the vessels of the brain and lead to a blockage of the vessels.
The same applies to the calcification of the carotid artery. With this, however, there is also the risk that the vessel itself becomes so calcified that not enough blood can reach the brain from the heart, which can then lead to a stroke. If a stroke was triggered by a narrowing of the carotid artery, this usually requires therapy, as there is a high risk of recurrence of 3-6% per year.
You might also be interested in the following topic: Calcified carotid artery - causes, diagnosis & therapy
The hardening of the arteries is closely related to other risk factors for a stroke and is in part promoted by these itself. Smoking, high blood pressure or diabetes also lead to an increased risk of arteriosclerosis.
Read more on this topic at: Causes of atherosclerosis
Blood clots
In addition to the local narrowing of blood vessels in the brain and its supplying vessels, blood clots that develop in other parts of our circulatory system can also lead to a stroke. These are then conducted into the brain via the arteries and as a result usually clog smaller cerebral vessels. This process is called an embolism.
The main cause of the formation of such clots is atrial fibrillation. However, other cardiac diseases such as a heart attack, inflammation of the myocardium or calcification of the heart valves can also be the cause of the formation of blood clots. Therefore, in terms of prevention, it is important to always adjust atrial fibrillation and other heart diseases well by means of adequate therapy in order to prevent the formation of blood clots.
Read more on the subject at: Blood clots in the head
Cerebral hemorrhage
With a share of around 20%, cerebral hemorrhages represent the second common cause of a stroke in addition to the occlusion of a cerebral vessel. This is called a hemorrhagic cerebral infarction. The bleeding is caused by the bursting of a brain vessel, which leads to bleeding into the brain or the surrounding spaces and thus to nerve cell damage.
Depending on the location, different forms of bleeding are distinguished, each showing different risk factors and courses. An intracerebral hemorrhage, i.e. a direct bleeding into the brain tissue, is triggered by high blood pressure and hardening of the arteries. This is the most common type of bleeding that leads to stroke.
Another important form of cerebral hemorrhage in this context is subarachnoid hemorrhage, i.e. bleeding into the space between brain tissue and the soft meninges. This usually does not arise traumatically, but rather through the bursting of a vascular sac (brain aneurysm). There is profuse bleeding, which spreads and thus causes the brain tissue to be displaced. Cell damage occurs.
For stroke therapy, it is essential to differentiate between vascular occlusion and cerebral haemorrhage, i.e. the cause of the stroke, since all further therapeutic steps depend on this. In principle, cerebral hemorrhage is treated differently than a vascular occlusion caused by a blood clot or vascular calcification.
Read more on the subject at: What are the causes of a cerebral hemorrhage?
These are the typical risk factors
There are risk factors that we cannot influence. These unchangeable risk factors include:
- Age
- Genetic predisposition
- Male gender
There are also risk factors that we can influence or treat. These changeable risk factors include:
- High blood pressure (arterial hypertension)
- Diabetes mellitus
- High cholesterol
- Overweight (adipostias)
- Smoke
- stress
- Alcohol consumption
- Sedentary lifestyle
- Heart conditions, such as atrial fibrillation or an open foramen ovale
- Clotting disorders
- Migraines with aura
- Use of medication, such as oral contraceptives or cortisone
high blood pressure
High blood pressure, also known as arterial hypertension, is the most important risk factor for the development of strokes. This is due to the direct increase of the risk to 4-5 times, but also to its influence on other risk factors such as arteriosclerosis caused by a high blood pressure are promoted. In addition, with a share of 25-40% in the population, high blood pressure is by far the most common risk factor.
High blood pressure promotes the development of vascular calcifications, the development of brain aneurysms and can itself lead to the development of cerebral hemorrhages. In addition, high blood pressure is the most controllable risk factor for strokes. This can usually be adequately treated with a healthy diet, sufficient physical activity and a medication approach, which is associated with a significant reduction in the risk of strokes.
Read more on the subject at: high blood pressure
Atrial fibrillation
Along with high blood pressure, atrial fibrillation is one of the most important risk factors for the development of a stroke. It is a cardiac arrhythmia that is associated with ineffective, uncoordinated contractions of the atrial muscles. These create turbulent currents in the atria, which increases the risk of blood clots forming.
If such a blood clot, also called a thrombus, forms in the left atrium, it can get through the carotid artery into the cerebral vessels and lead to an occlusion. This process is known as thromboembolism and is one of the most common causes of stroke. To prevent the formation of such thrombi, adequate anticoagulation with Marcumar or newer drugs (so-called NOACs) should always be carried out after the diagnosis of atrial fibrillation. You might be interested in the following topic: Anticoagulants
Read more on the subject at: Causes of atrial fibrillation
Smoke
Studies have shown a clear connection between cigarette consumption and the risk of stroke. Smokers are about 2-4 times more likely to get a stroke than non-smokers. This increased risk of smoking is mediated, among other things, by promoting high blood pressure and arteriosclerosis. Thus, in any case, it is not advisable to consume cigarettes in order to keep the risk of a stroke low. Even if the risk of stopping nicotine consumption does not drop back to the base value, a significant risk reduction can be determined by stopping nicotine consumption.
Read more on the subject at: Circulatory disorders caused by smoking
Diabetes mellitus
Diabetes mellitus is a crucial risk factor for the development of strokes. Around every fifth stroke patient has been diagnosed with diabetes mellitus. This connection is mainly due to the significantly higher risk of arteriosclerosis, which ultimately causes the stroke.
Excessively high blood sugar levels lead to increased plaque formation in the vessels and thus to increasing vessel damage and narrowing. Especially in combination with other risk factors, diabetes can lead to an enormous increase in risk. While diabetes itself leads to a 2-4-fold increase in risk, this value rises to 10-12-fold in combination with simultaneous high blood pressure.
Read more on the subject at: Consequences of diabetes
High cholesterol
Since high cholesterol promotes the development of arteriosclerosis, this can also lead to an increased risk of strokes. This is especially true for cholesterol levels of more than 240 mg / dl. However, high cholesterol levels are less important in causing strokes than they are in heart attacks.
Read more on the subject at: Hypercholesterolemia
Obesity
Obesity is an important risk factor for strokes, especially due to the connection with arteriosclerosis, diabetes and high blood pressure. It is assumed that obesity, i.e. a BMI of> 30kg / m2, causes a 2-3-fold increase in the risk of stroke. However, since abdominal fat is the main cause of this increase in risk, the abdominal circumference is usually used to estimate the risk in addition to the BMI. Women with a waist circumference of> 88 cm have a significantly higher risk, while this limit value is 102 cm for men.
Read more on the subject at: Consequences of being overweight
Sedentary lifestyle
It is now common knowledge that exercise is good for your health. The lack of physical activity, on the other hand, can increase the risk of various diseases such as dementia, cardiovascular disease and stroke. This connection is based primarily on the fact that a lack of exercise is often associated with high blood pressure, arteriosclerosis and diabetes. So in order to keep the risk of a stroke as low as possible, regular physical activity is advisable, even if this only means a long walk.
alcohol
The role of alcohol as a risk factor for stroke depends largely on the amount of consumption. Studies have shown that moderate alcohol consumption only slightly increases the risk of cerebral haemorrhage. However, if alcohol is consumed in large quantities, the risk of cerebral haemorrhage and vascular occlusion in the brain increases. For women, the limit is 0.3l of beer or 0.15l of wine and for men, 0.5l of beer or 0.25l of wine per day.
Read more on the subject at: Consequences of alcohol
stress
The connection between stress and an increased risk of stroke has now been proven in several studies. They come to the conclusion that stress at work in particular is decisive for this. Employees who work in a stressful job with little independent control are particularly affected. The increase in risk is estimated at 20-30% and mainly includes the increased occurrence of strokes due to a vascular occlusion, whereas cerebral haemorrhage occurs as the cause with equal frequency.
Read more on the subject at: Consequences of stress
migraine
Recent studies have shown a link between the presence of migraines and the risk of stroke. However, this can only be observed in migraine forms that are accompanied by a so-called aura. The term aura describes symptoms such as a visual disturbance or abnormal sensations, but also stomach problems or nausea that occur before the start of a migraine. The risk increase is approximately a factor of 2.
It should be noted, however, that most migraine sufferers are very young and generally have a very low risk of a stroke. Even a risk increase of a factor of 2 has only a small influence on the absolute risk. Nevertheless, migraineurs with an aura should be careful to avoid possible avoidable risk factors, such as obesity, in order to prevent strokes from developing.
Read more on the subject at: migraine
Heart valve diseases
Heart valve diseases can also increase the risk of blood clots and thus the risk of strokes. This particularly affects the aortic valve, since after this the blood is pumped directly into the cerebral vessels. If there is a calcification of the valve and thus a narrowing, one speaks of an aortic valve stenosis.
From a certain degree of constriction, the indication for a valve replacement is made. These artificial valves are usually made of plastic, which means that the risk of thrombus formation is high on this material. For this reason, after the insertion of such valves, anticoagulation is also carried out in order to prevent a stroke from occurring.
Read more on the subject at: Calcified heart valve
Blood clotting disorder
Congenital and acquired blood clotting disorders can increase the risk of stroke. What these have in common is that they increase the coagulability of the blood and thus promote the formation of blood clots. This is the case, for example, with a protein C and protein S deficiency. This lacks proteins that normally lead to an effective inhibition of blood coagulation. Triggered by various factors, a deficiency in these proteins can occur, which then leads to increased blood clotting. Other diseases in this spectrum are factor V disease or resistance to activated protein C.
Read more on the subject at: Bleeding disorders
Causes of stroke in the baby
Around 300 children and young people in Germany are diagnosed with a stroke every year. While many connections in the development of these rare strokes have not yet been sufficiently clarified, hereditary coagulation disorders in particular can now be identified as the main cause.
The symptoms of a stroke at a young age can be significantly different from those in adults. Some symptoms, such as a language disorder or poor walking, sometimes only become apparent after months, which can make diagnosis much more difficult. Nevertheless, compared to adults, children have a very good prognosis, as the brain growth is not yet complete and the function of the nerve cells that have died can often be compensated for. 90% of children can lead a normal life after a stroke and are not dependent on outside help. Nevertheless, around one in ten children must continue to live with major neurological impairments.
