A cerebrovascular accident, commonly called a stroke, happens when blood flow to part of the brain is suddenly cut off. Without oxygen and nutrients from the blood supply, brain cells begin dying within minutes. Stroke is the third leading cause of death and disability worldwide, with roughly 11.9 million new cases each year.
How a Stroke Happens
Your brain depends on a constant supply of oxygen-rich blood. When a blood vessel leading to or inside the brain is blocked or bursts, the area of brain tissue it feeds loses its supply. The cells in that area start dying almost immediately, and the longer blood flow stays disrupted, the more permanent the damage becomes. The specific abilities you lose, whether movement, speech, or vision, depend on which part of the brain is affected.
The Three Types of Stroke
Not all strokes happen the same way. The type determines both the immediate treatment and the long-term outlook.
Ischemic Stroke
This is by far the most common type, accounting for 87% of all strokes. It occurs when a blood vessel supplying the brain becomes blocked, usually by a blood clot. The clot may form locally in a narrowed brain artery or travel from elsewhere in the body, often the heart.
Hemorrhagic Stroke
A hemorrhagic stroke occurs when a weakened blood vessel ruptures and bleeds into or around the brain. The two most common structural causes are aneurysms (balloon-like bulges in a vessel wall) and abnormal tangles of blood vessels. Uncontrolled high blood pressure is the leading trigger.
Transient Ischemic Attack
Sometimes called a “mini-stroke,” a transient ischemic attack (TIA) is caused by a temporary clot that resolves on its own. Symptoms may last only minutes. A TIA is a serious warning sign that a full stroke could follow, and it requires urgent medical evaluation.
Recognizing the Symptoms
The acronym BE FAST is a practical way to spot a stroke quickly:
- Balance: Sudden loss of coordination, unsteady walking, or dizziness.
- Eyes: Blurred vision, double vision, or sudden loss of sight in one or both eyes.
- Face: One side of the face droops or goes numb. The person may not be able to smile evenly.
- Arms: Sudden weakness or numbness in one arm. If the person raises both arms, one drifts downward.
- Speech: Words come out slurred, garbled, or not at all. The person may also struggle to understand what you’re saying.
- Time: Call emergency services immediately. Every minute without treatment means more brain tissue lost.
These symptoms typically appear suddenly, not gradually over hours or days. That sudden onset is the hallmark of a stroke and the signal to act fast.
Major Risk Factors
High blood pressure is the single biggest risk factor for stroke. It damages blood vessel walls over time, making them more prone to both blockages and ruptures. Most other major risk factors feed into or worsen this damage.
High cholesterol contributes to plaque buildup inside arteries, including those that supply the brain, gradually narrowing them. Diabetes independently raises stroke risk. Obesity drives up “bad” cholesterol, blood pressure, and blood sugar simultaneously. Heart conditions, particularly atrial fibrillation (an irregular heartbeat), can cause blood clots to form in the heart and travel to the brain.
Lifestyle factors play a significant role. Smoking damages blood vessels and reduces the oxygen your blood can carry. Even secondhand smoke exposure increases risk. Excessive alcohol raises blood pressure and harmful blood fats. A diet high in saturated fat, trans fat, and sodium, combined with too little physical activity, accelerates nearly every risk factor on this list. The good news is that all of these are modifiable, meaning changes in behavior and treatment can meaningfully reduce your chances.
How Stroke Is Diagnosed
When someone arrives at the emergency department with stroke symptoms, a CT scan of the brain is almost always the first imaging test. CT is fast and widely available, and its primary job in the first minutes is to determine whether the stroke is caused by a blockage or a bleed, because the treatments are completely different.
MRI offers higher sensitivity for detecting early ischemic damage, more precise localization of the affected area, and a better ability to distinguish a true stroke from conditions that mimic one. It can also help estimate how long ago the stroke began in patients who woke up with symptoms or can’t say when they started. Some hospitals are increasingly using MRI as part of the initial workup, though CT remains the default first step due to speed.
Emergency Treatment
For ischemic strokes, the primary emergency treatment is a clot-dissolving medication given through an IV. The standard window for this treatment is within 4.5 hours of symptom onset. For patients who woke up with symptoms or have an unclear timeline, advanced brain imaging can identify whether enough salvageable tissue remains, potentially extending the treatment window up to 9 hours from the midpoint of sleep.
When a large blood vessel in the brain is blocked, a procedure called mechanical thrombectomy may be performed. A catheter is threaded through a blood vessel, typically starting at the groin, up to the clot in the brain, where a device physically removes it. This procedure can be performed up to 24 hours after symptom onset in carefully selected patients whose brain imaging shows there is still tissue worth saving. It is recommended for blockages in the large arteries of the front part of the brain when imaging confirms a mismatch between the area already damaged and the area still at risk.
For hemorrhagic strokes, the priority is controlling bleeding and reducing pressure inside the skull. Clot-dissolving medications would make things worse and are not used.
Recovery and Rehabilitation
The typical hospital stay after a stroke is five to seven days. During that time, the care team evaluates which functions were affected, including movement, speech, swallowing, vision, and cognition, to build a rehabilitation plan.
The first three months are the most critical period for recovery. This is when the brain is most responsive to rehabilitation and when patients see the greatest improvement. Most people enter an inpatient or outpatient rehabilitation program during this window. Physical and occupational therapy focus on restoring the ability to perform daily tasks: walking, dressing, bathing, eating, and using your hands. Therapists also work with patients to set personalized goals around activities that matter to them, whether that’s returning to work, driving, or a specific hobby.
After six months, improvement continues but slows considerably. Some people achieve a full recovery, while others reach a plateau with lasting impairments. The brain’s ability to rewire itself, a process called neuroplasticity, means gains are still possible beyond the six-month mark, but they require sustained effort and practice.
Preventing a Second Stroke
Someone who has had one stroke or TIA is at significantly elevated risk for another. Prevention after a first event involves both lifestyle changes and, for most people, medication.
Cholesterol-lowering medication is a cornerstone of secondary prevention. Clinical trials have shown that aggressive cholesterol reduction, targeting “bad” cholesterol levels below 70 mg/dL, is more effective at preventing repeat strokes than more moderate targets. For people with atrial fibrillation, long-term blood-thinning medication dramatically reduces the chance of a clot forming in the heart and traveling to the brain. Newer oral blood thinners carry a lower bleeding risk than older options and are now preferred for most patients.
In the first weeks after a minor stroke or TIA, a short course of dual blood-thinning therapy (two medications together) reduces the risk of an early recurrent stroke. This combination is typically used for about 21 days and then stepped down to a single medication, since continuing both beyond 90 days increases bleeding risk without added benefit.