Stroke
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stroke warning signs FAST symptoms 2025
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Here is a complete breakdown of stroke warning signs, drawn from authoritative medical textbooks.
Stroke Warning Signs
A stroke is a medical emergency. The core principle is: "TIME IS BRAIN" - every minute without treatment, approximately 1.9 million neurons die. Warning signs appear suddenly and without warning.
The BE-FAST Mnemonic
The American Heart Association endorses BE-FAST as the standard public-facing tool to recognize stroke:
| Letter | What to Check | Positive Sign |
|---|---|---|
| B | Balance | Sudden loss of balance or coordination |
| E | Eyes | Sudden blurred, double, or lost vision in one or both eyes |
| F | Face | Ask the person to smile - does one side droop or feel numb? |
| A | Arms | Ask them to raise both arms - does one drift downward? |
| S | Speech | Ask them to repeat a phrase - is it slurred, strange, or confused? |
| T | Time | Call emergency services immediately if you see any one of these signs |
The original FAST (Face, Arms, Speech, Time) is simpler and remains widely used. BE-FAST adds Balance and Eyes to capture posterior circulation strokes that FAST alone may miss.
Complete List of Sudden-Onset Warning Signs
According to Harrison's Principles of Internal Medicine (22nd ed.) and Park's Textbook of Preventive & Social Medicine, the warning signs of stroke include sudden onset of:
- Weakness or numbness of the face, arm, or leg - most often on ONE side of the body (about 85% of ischemic stroke patients have one-sided weakness/hemiparesis)
- Confusion or difficulty speaking or understanding speech (aphasia, dysarthria)
- Vision problems - blurred, double vision, or sudden loss of vision in one or both eyes
- Difficulty walking - sudden dizziness, loss of balance, or loss of coordination
- Severe headache with no known cause ("thunderclap" - especially in hemorrhagic stroke)
- Fainting or loss of consciousness
From Harrison's Principles of Internal Medicine, 22E: "patients and their family members should be counseled to call emergency medical services immediately if they experience or witness the sudden onset of any of the following: loss of sensory and/or motor function on one side of the body... change in vision, gait, or ability to speak or understand; or a sudden, severe headache."
Why "Sudden" Is the Key Word
The hallmark that distinguishes stroke from other neurological conditions is abrupt, sudden onset:
- Embolic or hemorrhagic strokes tend to produce maximum deficit at onset
- A "stuttering" or waxing-and-waning deficit may suggest thrombosis or a TIA (Transient Ischemic Attack)
- TIA produces the same warning signs but resolves within minutes to hours - it is still a medical emergency because it signals high short-term stroke risk
Stroke Mimics to Be Aware Of
Several conditions can look like a stroke but are not:
| Mimic | Distinguishing Feature |
|---|---|
| Seizure | May have convulsive activity before deficit |
| Migraine (acephalgic) | Sensory changes that migrate slowly over minutes across a limb |
| Brain tumor | Gradual onset; stroke-like only if there is hemorrhage or seizure |
| Metabolic encephalopathy | Fluctuating mental status, usually no focal deficit |
| Hypoglycemia | Clears rapidly with glucose correction |
What to Do If You Suspect a Stroke
- Call emergency services immediately - do not wait to see if symptoms resolve
- Note the exact time symptoms started - this determines eligibility for clot-busting treatment (tPA is given within 3-4.5 hours of onset)
- Do not give food, water, or medication by mouth - swallowing may be impaired
- Keep the person calm and lying down with head slightly elevated
Stroke/TIA management pathway - Harrison's Principles of Internal Medicine, 22E
Here is a helpful explainer video on BE-FAST from a UC Davis neurologist:
Sources:
- Harrison's Principles of Internal Medicine, 22E (2025), Cerebrovascular Disease chapter
- Park's Textbook of Preventive and Social Medicine, p. 8239-8252
- The Washington Manual of Medical Therapeutics, p. 2452-2456
- AHA Journal: FAST mnemonic and stroke recognition
- Mayo Clinic: BE FAST stroke warning signs
Pathophysiology of stroke
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pathophysiology of stroke ischemic hemorrhagic mechanisms 2024 2025
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