What Is a Stroke?
A stroke occurs when the blood supply to certain brain areas is 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 (ischaemic stroke) or by a bleeding in the brain (haemorrhagic stroke). About 85 percent of strokes are ischaemic and only 15 percent are hemorrhagic.1 According to the UK Stroke Organisation, Stroke occurs approximately 152,000 times a year in the UK. That's around one every 3 minutes. 1 in 4 strokes are fatal within a year. Stroke is the fourth single largest cause of death in the UK and second in the world. There are over 1.2 million stroke survivors in the UK. 2 In some cases, a transient ischaemic attack (TIA) precedes stroke. A transient ischaemic attack (TIA) is often labelled 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 are 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 (link to atrial fibrillation). Atrial fibrillation 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.3
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 (both sides). 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 haemorrhagic stroke (bleeding) and ischaemic (blocked artery), which is crucial for deciding on further therapies. In the case of ischaemic 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 t have caused stroke an electrocardiogram (ECG) gives information about the heart rhythm. If no cause for a stroke can be found, a small heart monitor (sometimes called an implantable cardiac monitor or ICM) can help determine whether previously unrecognised atrial fibrillation was the cause of an ischaemic stroke. Atrial fibrillation (AF) is though to increase the risk of a stroke by 5% each year.
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
- Weight loss, if overweight
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. (linked to stroke therapy options)