A stroke, in older medical language a cerebrovascular accident (CVA), happens when blood flow to part of the brain is blocked or a blood vessel in the brain bursts. Without oxygen and nutrients, brain cells begin to die within minutes, which is why every minute counts. This article explains the types of stroke, how to recognize one, how it is treated in the emergency room and what rehabilitation involves. It is general information and does not replace medical advice; anyone with stroke symptoms should call 911 immediately.
What Happens in a Stroke
The brain depends on a constant supply of blood. When an artery is blocked or ruptures, the area it supplies is damaged, and the symptoms depend on where that area is. A stroke in the left hemisphere often affects the right side of the body and language; a stroke in the right hemisphere often affects the left side and spatial awareness. A stroke in the brainstem or cerebellum can cause dizziness, double vision, swallowing problems and loss of coordination. Around the core of dead tissue lies an area that can still be saved if blood flow is restored quickly, which is the aim of emergency treatment.
Types of Stroke
Ischemic Stroke
About 87 percent of strokes are ischemic: a clot blocks an artery supplying the brain. The clot may form in a narrowed artery in the neck or brain, or travel from the heart, a common consequence of atrial fibrillation.
Hemorrhagic Stroke
In a hemorrhagic stroke a blood vessel bleeds, either into the brain tissue itself (intracerebral hemorrhage, often linked to long-standing high blood pressure) or into the space around the brain (subarachnoid hemorrhage, often from a ruptured aneurysm and typically announced by a sudden, extremely severe headache).
Transient Ischemic Attack (TIA)
A TIA, often called a mini-stroke, is a temporary blockage whose symptoms disappear, usually within minutes. It leaves no lasting symptoms but is a warning sign of a future stroke and needs urgent evaluation. More detail is in our article on mini-strokes.
Stroke in the United States
| Key figures (Centers for Disease Control and Prevention) | |
|---|---|
| Strokes per year | More than 795,000 |
| First strokes | About 610,000 |
| Strokes in people who had one before | About 185,000 (roughly 1 in 4) |
| How often | A stroke every 40 seconds; a death from stroke every 3 minutes 14 seconds |
| Costs | Nearly $56.2 billion in 2019–2020, including health care, medicines and missed work |
| Disability | A leading cause of serious long-term disability; reduces mobility in more than half of survivors aged 65 and older |
| Age | In 2014, 38 percent of people hospitalized for stroke were younger than 65 |
Recognizing a Stroke: BE FAST
- B – Balance: sudden loss of balance or coordination.
- E – Eyes: sudden loss of vision in one or both eyes, or double vision.
- F – Face: one side of the face droops; the smile is uneven.
- A – Arms: one arm is weak or numb and drifts down when both are raised.
- S – Speech: slurred speech, wrong words or trouble understanding.
- T – Time: call 911 right away, even if the symptoms go away.
Other warning signs are a sudden severe headache with no known cause, sudden numbness and sudden confusion. Note the time the symptoms started or when the person was last seen well, because treatment decisions depend on it. Do not drive to the hospital: ambulance crews can start assessment on the way, alert the hospital and take the patient to a stroke center.
Risk Factors
Many risk factors can be treated or changed:
- high blood pressure, the most important single risk factor;
- smoking;
- diabetes;
- high LDL cholesterol;
- atrial fibrillation, an irregular heart rhythm that lets clots form in the heart;
- obesity and physical inactivity;
- heavy drinking.
Others cannot be changed but raise the importance of the first group: age (the risk roughly doubles each decade after 55), a previous stroke or TIA, family history and sickle cell disease.
Diagnosis in the Emergency Room
The first question is whether the stroke is caused by a clot or a bleed, because the treatments are opposite. A CT scan or MRI of the brain answers it. CT angiography shows whether a large artery is blocked, which decides whether the clot can be removed with a catheter. Blood tests and heart rhythm monitoring look for other causes and for atrial fibrillation.
Emergency Treatment
Ischemic Stroke: Clot-Dissolving Drugs and Thrombectomy
Eligible patients can receive a clot-dissolving drug through a vein, either alteplase or tenecteplase, which the FDA approved for acute ischemic stroke in March 2025. It is generally given within 4.5 hours of the start of symptoms or of the time the patient was last known well. Patients with a blocked large artery may also have a mechanical thrombectomy, in which a catheter threaded from the groin or wrist removes the clot; in selected patients this is possible up to 24 hours after onset. The earlier treatment begins, the more brain tissue can be saved. Both treatments carry a risk of bleeding and are not suitable for everyone; the stroke team decides based on imaging and medical history.
Hemorrhagic Stroke
Treatment focuses on stopping the bleeding from getting worse: lowering blood pressure, reversing blood thinners and, in some cases, surgery. A ruptured aneurysm is sealed from inside with small coils or from outside with a clip.
Stroke Centers
Hospitals are certified at four levels: Acute Stroke Ready Hospitals can diagnose and start clot-dissolving treatment; Primary Stroke Centers have dedicated stroke units; Thrombectomy-Capable Stroke Centers can remove clots; Comprehensive Stroke Centers treat the most complex cases, including hemorrhages and aneurysms.
Common Effects of a Stroke
- weakness or paralysis of one side of the body (hemiparesis or hemiplegia);
- aphasia, difficulty speaking, understanding, reading or writing;
- dysarthria, slurred speech, and dysphagia, difficulty swallowing;
- neglect of one side of space, most often after right-hemisphere strokes;
- loss of part of the visual field;
- problems with memory, attention and planning;
- fatigue, and depression, which affects about one in three survivors and is treatable;
- spasticity and shoulder pain on the weak side.
Stroke Rehabilitation
When It Starts
Rehabilitation begins in the hospital as soon as the patient is medically stable, with sitting up, swallowing assessment and first transfers. The American Heart Association/American Stroke Association guideline on adult stroke rehabilitation (2016) advises against high-dose, very early mobilization within the first 24 hours.
Where It Happens
The same guideline recommends that patients who qualify be treated in an inpatient rehabilitation facility, with about three hours of therapy a day, rather than in a skilled nursing facility. Rehabilitation then continues in day rehab, outpatient clinics or at home. Our overview of rehabilitation hospital services explains these settings.
What Therapy Involves
Therapy is built on repetitive, task-specific practice: standing up, walking, reaching, dressing, speaking. Physical therapists use gait training, sometimes with body-weight support; occupational therapists may use constraint-induced movement therapy, in which the stronger arm is restrained so the weaker one is used; speech-language pathologists treat aphasia and swallowing problems.
How Recovery Unfolds
The fastest improvement usually comes in the first three months, when the brain reorganizes most actively. Improvement can continue for much longer with practice, and many survivors keep gaining skills a year or more later. How much function returns varies widely and depends on the size and location of the stroke, the speed of treatment and other health conditions.
Preventing Another Stroke
About one in four strokes happens to someone who has had one before, so prevention starts at discharge. Depending on the cause, doctors prescribe:
- blood pressure control, usually with medication;
- antiplatelet medicine such as aspirin after an ischemic stroke or TIA;
- anticoagulants for atrial fibrillation;
- statins to lower cholesterol;
- help to quit smoking, diabetes control and regular physical activity.
Frequently Asked Questions
What are the warning signs of a stroke?
Sudden loss of balance, vision problems, a drooping face, weakness in one arm and slurred or confused speech (BE FAST), as well as a sudden severe headache. Call 911 immediately.
How soon must treatment start?
As soon as possible. Clot-dissolving drugs are generally given within 4.5 hours of onset, and clot removal is possible up to 24 hours in selected patients, but results are better the earlier treatment starts.
How long does stroke recovery take?
The fastest gains are usually made in the first three months, but improvement can continue for a year or longer with ongoing practice.
Is a TIA dangerous?
The TIA itself passes, but it signals a high risk of a stroke, especially in the following days. It should be evaluated urgently, like a stroke; see also treatment of a mini-stroke.
This site is an independent reference on rehabilitation medicine and does not replace medical advice.
