What is a Stroke?
A stroke occurs when blood supply to certain areas of the brain are disrupted. A stroke is characterised by a massive and sudden disorder of the brain function, and may lead to severe and lasting impairments or death. Strokes are caused by either a blockage of a brain artery (ischemic stroke) or by a bleeding in the brain (hemorrhagic stroke). About 85 percent of strokes are ischemic and only 15 percent are hemorrhagic.1 In some cases, a transient ischemic attack (TIA) precedes stroke. A transient ischemic attack (TIA) is often labeled a “mini-stroke.” It causes the same neurological damage as stroke, e.g. blurred vision, slurred speech and signs of paralysis. However, most symptoms of a TIA disappear within an hour, whereas the neurological deficits caused by a stroke persist longer than 24 hours. Nonetheless, a TIA should be taken very seriously as it indicates that there is something wrong with blood supply to the brain and may be a warning sign for an impending stroke. It is therefore necessary to undergo a thorough medical checkup if you or someone you know experience any of the above mentioned symptoms. In about 30 percent of all strokes a distinct cause cannot be discovered via the usual diagnostic methods. Such cases are classified as cryptogenic strokes.
In general, cardiovascular disorders cause ischemic strokes. In arteriosclerosis , arteries narrow because blood cells, blood fats, and other substances build up deposits (plaques) on the vessel´s wall. This can reduce blood flow, leading to a sudden circulatory disorder in the brain and consequently to a stroke.
A high risk of stroke is associated with the cardiac arrhythmia atrial fibrillation, which leads to an increased risk of a blood clot (thrombus) forming in the heart. Such a blood clot may break free, float as a so-called emboli in the bloodstream into a brain artery and congest it, thereby causing a stroke. People with atrial fibrillation have at least a five times higher risk of suffering a stroke.2
Further risk factors for a stroke are:
- High blood pressure
- Dyslipidemia, or an elevated level of lipids in the bloodstream
- Obesity and lack of exercise
- Diabetes/ Diabetes mellitus
- Cardiac arrhythmias (atrial fibrillation)
- Moreover, the risk of cerebral hemorrhage or ischemic stroke may be increased by the following factors:
- Changes in the blood vessels, which cause vascular dementia
- Increased bleeding, e.g. hemophilia
- Malformations of blood vessels (aneurysms)
- Drug abuse
A stroke may lead to a wide variety of symptoms depending on the affected brain region and the extent of damage to the brain. Usually, one side of the body is affected. Only in rare cases do the symptoms occur bilaterally. Among others, any of the following symptoms can be observed:
- Facial paralysis: uneven smile, one side of the face droops
- Sudden weakness or paralysis in the arms and legs
- Blurred vision, double vision or blindness
- Numbness or prickling sensation in the face, legs or arms
- Loss of balance, dizziness
- Speech disorders: slurred speech, repeating words or syllables, amnesic aphasia, meaningless or garbled utterances, complete loss of ability to speak.
- Difficulty understanding people, loss of orientation, general confusion
The diagnosis is based on the medical history and a physician’s physical examination. A neurological examination provides first clues as to which brain regions are probably involved and how severe the brain damage may be. Diagnostic imaging like computed tomography (CT) and magnetic resonance imaging (MRI) enable physicians to distinguish between hemorrhagic stroke (bleeding) and ischemic (blocked artery), which is crucial for deciding on further therapies. In the case of ischemic stroke, contrast medium examination of the brain arteries (e.g., angiography) can help to locate the congested vessels.
In addition, the potential causes of the stroke must be detected. If atrial fibrillation is suspected to have caused the stroke, an electrocardiogram (ECG) gives information about the heart rhythm. If no cause for a stroke can be found, a small heart monitor can help determine whether previously unrecognised atrial fibrillation was the cause of an ischemic stroke. In addition, an ultrasound examination of the carotid artery can discover indications of arteriosclerosis of the brain arteries, which can also cause stroke.
Prevention is the safest and best protection against a stroke. By pursuing a healthy lifestyle, some risk factors can already be reduced or completely excluded in advance. A healthy lifestyle includes:
- A healthy diet with large portions of fruit and vegetables and foods low in sugar and fat
- Regular exercise and sports
- Adequate fluid intake, especially for older people who experience a decreased sensation of thirst
- Smoking cessation
- Avoiding stress
- Maintaining a healthy weight
If any risk factors do exist despite a healthy lifestyle, you should go to your doctor for a regular health check.
Click here for further information on stroke treatment options.