Stroke: definition, causes and risk factors
150,000 strokes per year in France — one every 4 minutes. Understanding what triggers this medical emergency and which risk factors can be controlled is the first step to protecting your brain.
1. Definition: what is a stroke?
A stroke is a sudden and abrupt interruption of blood flow to a part of the brain. Deprived of oxygen and glucose, brain cells suffer within 4 minutes and begin to die irreparably. Unlike cells in most organs, neurons do not regenerate — which explains the often permanent nature of the consequences when treatment is delayed.
There are two main categories of strokes, with radically different mechanisms and emergency treatments. The ischemic stroke (80% of cases) is caused by the blockage of a cerebral artery by a clot (thrombus formed on site) or an embolism (clot migrating from the heart or a peripheral artery). The hemorrhagic stroke (20%) is caused by the rupture of a cerebral blood vessel, leading to bleeding in or around the brain tissue.
⚡ TIA: the warning that should never be ignored
The Transient Ischemic Attack (TIA) produces the same symptoms as a Stroke but disappears spontaneously in less than 24 hours (usually in a few minutes). Contrary to what its name suggests, it is not "benign": 15 to 20% of people who have a TIA will have a full Stroke within the next 3 months, half of them within 48 hours. A TIA is an absolute medical emergency — call 15 immediately, even if the symptoms have disappeared.
2. Recognizing warning signs: the FAST method
🚨 FAST — Recognize a Stroke in 4 seconds
F — Face: Ask the person to smile. Facial asymmetry, a mouth deviated to one side, a drooping eyelid are warning signs.
A — Arms: Ask them to raise both arms. Inability to raise one arm or an involuntary drop on one side indicates motor weakness.
S — Speech: Ask them to repeat a simple sentence. Incoherent speech, incomprehensible words, inability to speak — these are alarm signs.
T — Time: Call 15 (SAMU) immediately. Do not wait to see if it goes away. Every minute counts.
Other signs may accompany these symptoms: sudden blindness in one eye or double vision, headaches of unusual intensity ("the worst pain of my life"), sudden dizziness with loss of balance or coordination, numbness or sudden paralysis on one side of the body. The therapeutic window for thrombolysis (treatment dissolving the clot in ischemic Stroke) is a maximum of 4h30 — hence the crucial importance of calling 15 without delay.
3. Types of Stroke: ischemic and hemorrhagic
| Characteristic | Ischemic Stroke | Hemorrhagic Stroke |
|---|---|---|
| Frequency | 80% of strokes | 20% of strokes |
| Mechanism | Obstruction of an artery by a clot | Rupture of a vessel, cerebral bleeding |
| Onset | Often gradual (minutes to hours) | Often sudden (seconds) |
| Headache | Rare or moderate | Severe, "thunderclap headache" |
| Emergency treatment | Thrombolysis and/or thrombectomy | Surgery or medical treatment depending on location |
| Triggering factor | Atrial fibrillation, atherosclerosis | Uncontrolled hypertension, aneurysm |
4. Risk factors
Modifiable factors: levers for action
High blood pressure — 1st risk factor for Stroke
Hypertension is responsible for 54% of strokes worldwide. A blood pressure ≥ 140/90 mmHg progressively weakens the walls of cerebral arteries, promotes the formation of atherosclerotic plaques, and multiplies the risk of Stroke by 4 to 6. Blood pressure control (medications + physical activity + salt reduction) is the most effective preventive intervention known.
Smoking — risk multiplied by 2 to 3
Tobacco multiplies the risk of ischemic Stroke by 2 to 3. It acts through several mechanisms: acceleration of atherosclerosis, increased blood viscosity, arterial spasms, and increased blood pressure. The good news: 5 years after quitting smoking, the risk of Stroke returns to the level of non-smokers.
AF — source of cardiac emboli
Atrial fibrillation (AF) is a heart rhythm disorder that multiplies the risk of Stroke by 5. It generates turbulence in the heart chambers, promoting the formation of clots that can migrate to the brain. Its treatment (anticoagulants, ablation) drastically reduces this risk.
Non-modifiable factors
Age is the main non-modifiable factor: the risk of Stroke doubles every 10 years after age 55. Personal history (a first Stroke or TIA multiplies the risk of recurrence by 10 in the following 90 days) and family history (a first-degree relative with a Stroke before age 65 doubles the risk) complete this picture.
5. DYNSEO resources on Stroke
🧠 DYNSEO Training — Understanding and supporting Stroke
• Training "Stroke: understanding the disease" — solutions for daily life
• Training "Stroke in institutions" — understanding the consequences and adapting practice
• Training "Cognitive disorders after a Stroke" — memory, attention, and daily life
• 62 cognitive stimulation tools — cognitive rehabilitation post-Stroke
FAQ
What is a Stroke?
A Stroke is a sudden interruption of blood flow in a part of the brain. Neurons deprived of oxygen die at a rate of 1.9 million per minute. There are two types: ischemic (80%, obstruction) and hemorrhagic (20%, vascular rupture).
What are the warning signs (FAST method)?
Face (facial asymmetry), Arms (inability to raise an arm), Speech (speech disorders), Time (call 15 immediately). These signs require emergency intervention even if they disappear spontaneously.
What are the modifiable risk factors?
High blood pressure (1st factor), smoking, diabetes, atrial fibrillation, obesity, physical inactivity, high cholesterol, excessive alcohol consumption. Addressing these factors can reduce the risk of Stroke by 80%.
Is Stroke common in France?
150,000 strokes per year in France, or one every 4 minutes. It is the leading cause of acquired disability in adults, the second leading cause of dementia, and the third leading cause of mortality.
Can a Stroke be prevented?
Yes, 80% of strokes would be avoidable. Blood pressure control (≤140/90), quitting smoking, 30 minutes of physical activity per day, and a Mediterranean diet are the most effective levers.
Conclusion: act before the emergency
A Stroke is still too often perceived as a fatality. The reality is more encouraging: a large majority of strokes are preceded by ignored warning signs, and most risk factors are controllable. Knowing the FAST method, regularly monitoring blood pressure, and consulting a doctor in case of TIA are three reflexes that can radically change the prognosis. DYNSEO training supports patients, caregivers, and professionals in better understanding this disease and its consequences.
