Medical Encyclopaedia › Stroke (short definition)
In brief: A stroke is a sudden disruption of blood flow or bleeding in the brain that causes nerve cells to die within a short time. It is an emergency: the sooner treatment begins, the more brain tissue can be saved.
Types and causes
Around four out of five strokes are ischaemic: a blood clot blocks a cerebral artery, for example as a result of arteriosclerosis of the carotid artery or as an embolism from the heart in atrial fibrillation. Less common is a haemorrhagic stroke due to bleeding in the brain, often with long-standing high blood pressure, or a subarachnoid haemorrhage from a ruptured aneurysm. If the deficits resolve completely within a short time, it is called a transient ischaemic attack (TIA); it is considered a serious warning sign of an impending stroke.
Recognising the warning signs
Suddenly occurring symptoms are typical: paralysis or numbness on one side of the body, a drooping corner of the mouth, speech or comprehension difficulties, visual disturbances or double vision, dizziness with unsteady gait, and a sudden, very severe headache. The BE-FAST test (Balance, Eyes, Face, Arms, Speech, Time) serves as a memory aid: check balance and vision, ask the person to smile, to raise both arms, to repeat a simple sentence – and if anything is abnormal, call the emergency number (112 in Europe) immediately. Even if the symptoms disappear quickly, immediate assessment is necessary.
Treatment in hospital
Care ideally takes place on a specialised stroke unit. A CT or MRI scan first clarifies whether there is a vascular occlusion or bleeding. In ischaemic stroke, the clot can be dissolved with a medicine within a limited time window (thrombolysis); for occlusions of large vessels, it is additionally or solely removed with a catheter (thrombectomy). Both procedures carry risks, above all bleeding, and are weighed up individually. In cerebral haemorrhage, the focus is on lowering blood pressure, reversing anticoagulant medicines and, if necessary, surgery.
Rehabilitation and follow-up care
Many of those affected are left with paralysis, speech, swallowing or memory disorders. Early rehabilitation with physiotherapy, occupational therapy, speech therapy and neuropsychological treatment helps to regain or compensate for lost abilities. Depression after a stroke is also common and treatable.
Prevention
The most important modifiable risk factor is high blood pressure. In addition, there are atrial fibrillation, diabetes, raised blood lipids, smoking, lack of exercise, overweight and high alcohol consumption. Regular blood pressure checks, treatment of atrial fibrillation with anticoagulants, a smoke-free life and exercise significantly reduce the risk. After a stroke, medicines are used depending on the cause to prevent a further event.
Related terms in the encyclopaedia
Transient ischaemic attack (TIA), Stroke unit, Thrombolysis, Thrombectomy, Cerebral haemorrhage, Aphasia, Atrial fibrillation, Arteriosclerosis, Carotid stenosis, Hemiparesis
Further reading on Medizin Aktuell
Sources
- Deutsche Gesellschaft für Neurologie (DGN): S2e-Leitlinie „Akuttherapie des ischämischen Schlaganfalls“, AWMF-Register 030-046
- Deutsche Gesellschaft für Allgemeinmedizin und Familienmedizin (DEGAM): S3-Leitlinie „Schlaganfall“, AWMF-Register 053-011
- IQWiG: gesundheitsinformation.de – Gesundheitsinformationen des Instituts für Qualität und Wirtschaftlichkeit im Gesundheitswesen
Note: This article is for general information and does not replace advice, diagnosis or treatment from a doctor or pharmacist. Last updated: October 2026.