What is Stroke?
A stroke happens when blood flow to part of the brain is blocked by a clot or when a blood vessel bursts and bleeds. Brain cells begin dying within minutes, so stroke is always a medical emergency. Use BE-FAST — Balance loss, Eyes or vision change, Face droop, Arm weakness, Speech difficulty, Time to call emergency services immediately.
Key takeaways
- Call emergency services at the first sign of stroke; treatment windows for clot-busting therapy are measured in hours.
- BE-FAST covers more strokes than FAST alone because it adds sudden balance loss and vision change.
- About 87% of strokes are ischemic (a blockage); the rest are hemorrhagic (bleeding), and the treatments are opposite.
- A transient ischemic attack has the same symptoms that resolve, and is a serious warning of a stroke to come.
- High blood pressure is the single largest modifiable risk factor for stroke.
Overview
A stroke is a sudden interruption of blood supply to part of the brain. Because brain tissue has almost no energy reserve, cells in the affected area begin to die within minutes, and the surrounding at-risk zone can survive only for a limited time. Whatever function that region controlled — moving an arm, forming words, seeing to one side, keeping balance — is lost abruptly. That abruptness is the defining feature: stroke symptoms appear suddenly and reach their peak within seconds to minutes rather than building over hours.
The reason speed matters so much is that effective treatments exist but are time-limited. Clot-dissolving medication and mechanical clot removal can restore blood flow and dramatically change the outcome when delivered early. Every minute of delay costs surviving brain tissue. This is why the correct response to any sudden neurological symptom is to call emergency services rather than to lie down, wait for it to pass, or drive to a clinic.
What Stroke is
Ischemic stroke, which accounts for roughly 87% of cases, occurs when a clot blocks an artery supplying the brain. The clot may form on a plaque in a neck or brain artery, or travel from the heart — commonly from atrial fibrillation. Small vessel disease deep in the brain causes another important subtype, closely tied to long-standing high blood pressure and diabetes.
Hemorrhagic stroke occurs when a vessel ruptures, either into the brain tissue itself or into the space around the brain from an aneurysm. The symptoms overlap with ischemic stroke, which is why brain imaging is done immediately — clot-dissolving treatment would be dangerous in bleeding. A transient ischemic attack (TIA) produces identical symptoms that resolve completely, usually within an hour, and signals a high short-term risk of a full stroke.
Common symptoms
Stroke symptoms begin suddenly and typically affect one side of the body or one specific function.
- Face drooping on one side, or an uneven smile
- Arm or leg weakness or numbness, usually on one side
- Speech difficulty — slurred words, wrong words, or inability to understand others
- Sudden loss of balance, coordination, or an unexplained fall
- Sudden vision change — loss in one eye, double vision, or loss of one side of the visual field
- Sudden severe headache with no known cause, particularly with vomiting or neck stiffness
- Sudden confusion or difficulty following a conversation
Less common symptoms
- Sudden dizziness or spinning with nausea and inability to walk
- Difficulty swallowing
- Sudden behaviour or personality change
- Seizure at onset — more common with hemorrhagic stroke
- Neglect of one side of the body or of the space around it
Risk factors
- High blood pressure — the single largest modifiable risk factor for both stroke types
- Atrial fibrillation — allows clots to form in the heart and travel to the brain
- Smoking — roughly doubles ischemic stroke risk and raises hemorrhagic risk too
- Diabetes — accelerates both large and small vessel disease
- High LDL cholesterol and carotid artery disease — sources of clot and narrowing
- Previous stroke or TIA — the strongest predictor of a future event
- Age, family history, and Black or Hispanic ancestry — non-modifiable or partly social risk factors with substantial impact
- Obesity, physical inactivity, and heavy alcohol use — modifiable contributors
- Sickle cell disease and pregnancy-related conditions such as preeclampsia — specific elevated-risk situations
Causes
Ischemic strokes are caused by clots. These arise from atherosclerotic plaque in the carotid or intracranial arteries, from the heart in atrial fibrillation or after a heart attack, or from disease of the brain's small penetrating arteries — the last strongly linked to chronic high blood pressure and diabetes. Less common causes include arterial dissection after neck injury, clotting disorders, and inflammation of blood vessels, which are considered particularly in younger people.
Hemorrhagic strokes result from rupture of a weakened vessel. Long-standing high blood pressure is the usual background; cerebral amyloid angiopathy in older adults, arteriovenous malformations, aneurysms, and anticoagulant medication all contribute. Distinguishing bleeding from blockage is the first job of emergency imaging because the treatments are opposite.
How it is diagnosed
Emergency assessment prioritises rapid brain imaging, because treatment decisions depend on whether the stroke is ischemic or hemorrhagic.
| Test or assessment | What it looks at |
|---|---|
| Non-contrast CT of the head | The first imaging test in nearly every case. It rapidly identifies bleeding, which must be excluded before clot-dissolving therapy can be considered. |
| CT angiography and CT perfusion | Maps the arteries to locate a large-vessel blockage and estimates how much brain tissue is still salvageable, guiding decisions about clot retrieval. |
| MRI of the brain | More sensitive than CT for small or early ischemic strokes, particularly diffusion-weighted sequences, and useful for defining the pattern of injury. |
| Carotid ultrasound | Looks for narrowing in the neck arteries that may have been the clot source and may warrant procedural treatment. |
| Cardiac assessment | ECG, echocardiography, and prolonged rhythm monitoring to look for atrial fibrillation or a cardiac clot source. |
| Blood tests | Glucose, blood count, clotting studies, kidney function, and lipids — glucose in particular because low blood sugar can mimic stroke exactly. |
Treatment overview
Emergency treatment aims to restore blood flow or control bleeding, and is followed by rehabilitation and secondary prevention. The categories below describe standard approaches; every decision is made by the stroke team based on imaging and timing.
Intravenous thrombolysis
Clot-dissolving medication given within a limited window after symptom onset for eligible ischemic strokes, after bleeding has been excluded on imaging.
Mechanical thrombectomy
Catheter-based removal of a large-vessel clot, performed at specialist centres and effective in selected patients well beyond the thrombolysis window when imaging supports it.
Hemorrhagic stroke management
Rapid blood pressure lowering, reversal of anticoagulants where relevant, and neurosurgical intervention for selected bleeds or aneurysms.
Stroke unit care
Admission to a dedicated stroke unit improves survival and independence through monitoring, swallowing assessment, and early mobilisation.
Rehabilitation
Physical, occupational, and speech-language therapy, started early and continued for months. Recovery of function can continue well beyond the first weeks.
Secondary prevention
Antiplatelet or anticoagulant therapy depending on cause, intensive blood pressure and cholesterol control, glucose management, and smoking cessation.
Procedural prevention
Carotid endarterectomy or stenting for significant symptomatic narrowing, and closure of a patent foramen ovale in selected younger patients.
Lifestyle considerations
- Know and control your blood pressure — this does more to prevent stroke than any other single measure.
- If you have atrial fibrillation, take anticoagulation exactly as prescribed.
- Stop smoking; stroke risk falls substantially within a few years of quitting.
- Follow a Mediterranean or DASH-style eating pattern with limited sodium.
- Stay physically active most days — even walking has a measurable protective effect.
- Keep alcohol modest; heavy intake raises both ischemic and hemorrhagic risk.
- Attend rehabilitation consistently after a stroke and keep working on function at home.
- Screen for and treat depression after stroke; it is common and it slows recovery.
Prevention
- Treat high blood pressure to target — the single highest-yield preventive action.
- Detect and treat atrial fibrillation, including checking your own pulse periodically after 65.
- Lower LDL cholesterol, particularly after a TIA or ischemic stroke.
- Manage diabetes and prediabetes.
- Stop smoking and avoid secondhand smoke.
- Stay active, maintain a healthy weight, and limit alcohol.
- Take a TIA as seriously as a stroke — urgent assessment sharply reduces the risk of a completed stroke.
Warning signs and when to get help
Signs that need emergency care
If you believe you are experiencing a medical emergency, call emergency services immediately (911 in the United States).
- BE-FAST: sudden Balance loss, Eyes or vision change, Face drooping, Arm weakness, Speech difficulty — Time to call emergency services immediately
- Sudden numbness or weakness of the face, arm, or leg, especially on one side of the body
- Sudden confusion, trouble speaking, or trouble understanding speech
- Sudden trouble seeing in one or both eyes
- Sudden trouble walking, dizziness, or loss of coordination
- Sudden severe headache with no known cause, particularly with vomiting or neck stiffness
- Note the time symptoms started — it determines which treatments are possible — and do not drive yourself or take aspirin before assessment
Signs that warrant a prompt appointment
These are not emergencies, but they are worth a call to your clinician rather than a wait-and-see.
- Stroke-like symptoms that resolved completely — a TIA still needs urgent same-day assessment
- New difficulty swallowing, choking, or coughing while eating after a stroke
- Worsening weakness, spasticity, or pain in an affected limb
- Low mood, tearfulness, or loss of motivation during recovery
- Blood pressure readings persistently above your agreed target
Questions to ask a healthcare professional
Take these to your next appointment — or build an agenda with the Appointment Prep tool.
- What type of stroke did I have, and what caused it?
- What treatment did I receive, and what does that mean for my recovery?
- What is my blood pressure and cholesterol target now?
- Should I be on an antiplatelet or an anticoagulant, and why?
- Do I need carotid or cardiac testing to find the source?
- What rehabilitation is available to me, and for how long?
- When is it safe for me to drive, return to work, or fly?
- What symptoms should send me back to the emergency department?
Frequently asked questions
What does BE-FAST stand for?
Balance loss, Eyes or vision change, Face drooping, Arm weakness, Speech difficulty, and Time to call emergency services. It extends the older FAST acronym by adding balance and vision, which catches strokes in the back of the brain that FAST alone can miss.
Is a TIA serious if the symptoms went away?
Yes. A transient ischemic attack means a clot temporarily blocked flow and then cleared. The risk of a full stroke is highest in the following days, so a TIA warrants urgent same-day assessment even though you feel completely normal again.
Should I take an aspirin if I think I am having a stroke?
No. Unlike a suspected heart attack, aspirin is not advised before a stroke is imaged, because bleeding into the brain must be excluded first and aspirin would make that worse. Call emergency services and let the team decide.
How long does stroke recovery take?
The fastest gains usually come in the first three to six months, but meaningful improvement can continue for a year or longer with sustained rehabilitation. Recovery is uneven and varies enormously with the size and location of the stroke.
Can a stroke happen to a young person?
Yes, and it is becoming somewhat more common. Causes in younger adults more often include arterial dissection, heart defects such as a patent foramen ovale, clotting disorders, pregnancy-related conditions, and drug use, so the workup is broader.
What is the difference between ischemic and hemorrhagic stroke?
Ischemic stroke is caused by a blockage and makes up about 87% of cases; hemorrhagic stroke is caused by bleeding. They look similar at the bedside but need opposite treatments, which is why emergency brain imaging comes first.
Sources
- American Heart Association / American Stroke Association — Warning signs, treatment, and recovery resources
- CDC — Stroke — US burden, signs, and prevention
- NINDS — Stroke — NIH neurological overview and research
- MedlinePlus — Stroke — Consumer summary and rehabilitation links
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