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Overview: Stroke

Last Update: October 25, 2022; Next update: 2025.


Sudden paralysis, problems with eyesight and speech, and occasionally headache are the usual signs of a stroke. The cause is a clot blocking a blood vessel in the brain or bleeding in the brain (brain hemorrhage).

The exact symptoms mostly depend on what part of the brain is affected.

A stroke is a medical emergency that requires immediate treatment.

At a glance

  • A stroke happens when the blood supply to part of the brain is disrupted – usually due to a clot blocking a blood vessel.
  • Common symptoms include paralysis and speech problems.
  • To prevent permanent damage, it’s very important the person is treated quickly.
  • Rehabilitation helps ease the effects of a stroke.
  • Controlling risk factors, like high blood pressure, can prevent stroke.


Common signs of a stroke include:

  • A sudden feeling of weakness
  • Numbness and paralysis
  • Speech and language problems
  • Vision problems
  • Dizziness and trouble walking

Some people also have severe headaches, along with nausea, vomiting and unconsciousness.

Usually, only one side of the body is affected, making it impossible to move the right arm and/or right leg, for example. Drooping on one side of the mouth is another typical sign of a stroke.


In most cases, strokes are caused by a blood clot that is blocking a blood vessel in the brain. The clot usually forms in the carotid arteries or the heart. It then flows into the brain, where it blocks a blood vessel. A stroke that is caused by a blocked blood vessel is referred to as an ischemic stroke.

Bleeding (hemorrhage) in the brain is the second, less common cause. This occurs if, for instance, a blood vessel ruptures and blood leaks into the brain tissue.

In both cases, one part of the brain is no longer supplied with enough oxygen. Bleeding also increases the pressure on the brain tissue, which can cause additional damage. The sooner the treatment is started and the oxygen supply is restored, the better the chances are of minimizing damage to the brain.

Risk factors

It is very uncommon for blood clots to develop in the blood vessels of healthy people. But certain conditions, habits and genetic factors can increase the risk of a stroke. They include smoking, high blood pressure, high cholesterol, and atrial fibrillation.

Typical signs of a stroke that then go away on their own after a few hours may be signs of a transient ischemic attack (TIA). This happens when a blood clot forms but then breaks up again before the brain is damaged severely. People who have had a transient ischemic attack (TIA) are more likely to have a stroke.


Every year about 1 out of 1000 people have a stroke. The risk increases with age. On average, it’s somewhat more common in men than in women.


Most people survive strokes. But they can result in the following impairments:

  • Paralysis on one side of the body
  • Muscle spasms
  • Trouble swallowing
  • Speech and language problems
  • Problems paying attention and concentrating
  • Vision problems
  • Lack of awareness of the affected side of the body (neglect)
  • Mental health problems like depression or anxiety

Some people who’ve had a stroke need nursing care or support in their everyday lives.

Symptoms such as paralysis often get better over time, but they can also be permanent. Around 40 out of 100 people who survive a stroke have severe permanent impairments as a result.

And people who have had a stroke are also at greater risk of having another. About 5 out of 100 people who survive a stroke have another one within the space of a year. Other cardiovascular diseases, such as heart attacks, are also more likely to occur in people who have had a stroke. Around 30 out of 100 die within one year of having a stroke.


Strokes are medical emergencies. If you think you or somebody else might be having a stroke you should call for an ambulance immediately (112 in Germany and many other countries; 911 in the U.S.). Do not wait to see if the symptoms go away.

After the paramedics have examined the patient, he or she will be taken to hospital – if possible, one that specializes in strokes. There, comprehensive testing can be started immediately, so that the cause of the symptoms can be determined and treatment can be started soon afterwards. The tests typically include computed tomography (CT) or magnetic resonance imaging (MRI).


Whether or not particular preventive measures against a stroke are worthwhile will depend on whether the person has any other conditions and risk factors.

People with high blood pressure can reduce their risk of a stroke by taking blood-pressure-lowering medication. Anticoagulants are an option for people who are at greater risk of blood clots forming – for example, if they have atrial fibrillation. Cholesterol-lowering medication (statins) can also help prevent stroke.

These precautions can be helpful for people who’ve already had a stroke too because they lower the risk of a repeat stroke.

Sometimes, the doctor will recommend surgery to unblock blood vessels in a carotid artery for instance. If the blockage is severe and the symptoms are persistent, another option is to insert a stent. Stents are wire-mesh tubes used to ensure blood vessels stay open. But it is important to carefully consider the pros and cons of this type of surgery.


Acute treatment aims to save a person's life and minimize damage as much as possible. The type of treatment will mainly depend on whether the stroke was caused by a blood clot or a hemorrhage.

If it was a clot, the doctors will try to unblock the vessel as quickly as possible. There are two ways of doing this: Thrombolysis and thrombectomy. Thrombolysis involves taking medication via a drip to dissolve the clot. Thrombectomy is a procedure to remove the clot from blood vessels in the brain using a catheter. Where possible, the doctor will use a combination of these two methods. But they’re only feasible for the first few hours after symptoms start. That’s why it’s so important to get hospital treatment for a stroke quickly. Specialized stroke units are the best place to go.

Brain hemorrhages have to be stopped quickly, sometimes by operating.

Further treatment and need for observation depends on the severity of the stroke, the effects it had, and the results of further examinations.


Most people find it very important to regain their mobility, muscle strength, speech, and independence after having a stroke. Restoring emotional balance is also key.

There are various rehabilitation programs covering different points. Depending on the person’s needs, rehabilitation concentrates on physical therapy and fitness training, speech therapy and swallowing exercises. The aim is to minimize the physical effects of a stroke and to learn how to cope with them. Occupational therapy involves learning how to successfully cope with challenges in daily life as well as possible, despite the limitations.

Rehabilitation usually begins when the person is still being treated in hospital. It can be continued after in a special clinic or as an outpatient.

Everyday life

It is normal for people to feel sad and depressed after a stroke. Depending on how severe the stroke was, it can have an enormous impact on a person's life.

People who used to live independently and now have to rely on others for help have to come to terms with the effects of the stroke first – both the psychological consequences as well as the practical challenges in everyday situations.

Treatment and rehabilitation can help people to regain some of their independence after a stroke. Over time, most patients and their families manage to adapt their lives to the changes as best they can.

But some people develop depression as a result of a stroke, and need professional help for it. Often, it goes unnoticed or people think it’s a normal reaction and don’t take any action to treat it. Apart from the impact on mental health, depression can prevent proper physical recovery too. It is important that stroke patients and their families receive the support that they need to prevent depression, or are offered help if depression has already set in.

Further information

A lot of support is available for people who have had a stroke, as well as for their families. For instance, there are special information centers and support groups that can provide patients and their families with help concerning nursing care, finances, and psychosocial issues.

Family members can also take part in nursing care courses to learn things like basic care techniques.

The available services will depend on the center and can’t always be found immediately. We have put together a list of places that you can contact to find out where you can get help in your local area (in Germany only).

You’ll also find a useful list on the Deutsche Schlaganfall-Hilfe (German Stroke Foundation) website.


© IQWiG (Institute for Quality and Efficiency in Health Care)
Bookshelf ID: NBK279214


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