Ischemic Stroke

Neurological “Brain attack”

A sudden loss of blood supply to part of the brain, usually from a clot — every minute counts.

Educational summary only — not medical advice, and no substitute for assessment by a clinician. Diagrams are simplified illustrations.

A clot blocks an artery in the brain; the territory it supplied loses oxygen, and the abilities controlled by that area fail.

Overview

A stroke is a sudden interruption of the brain's blood supply. In an ischemic stroke — about 85% of cases — a clot blocks a brain artery. (The other type, hemorrhagic, is a bleed.) Brain cells need a constant supply of oxygen and glucose, and begin to fail within minutes without it, so stroke is a true emergency.

How the system normally works

A network of arteries delivers blood to every region of the brain. Because different regions control different functions — movement, sensation, speech, vision — the supply to each area is essential for that specific ability.

What goes wrong

A clot either forms in a narrowed brain artery or travels from elsewhere (often the heart, in atrial fibrillation, or a neck artery). With the artery blocked, the brain region it supplies stops working immediately and its cells start to die. A surrounding 'at-risk' zone can still be saved if flow is restored quickly — the basis of emergency treatment. Because each area has a job, the symptoms reveal where the blockage is.

Side-by-side diagram comparing an ischemic stroke from a clot and a hemorrhagic stroke from a burst, bleeding brain artery. — Two kinds of stroke: a blocked artery (ischemic, ~85%) versus a burst, bleeding artery (hemorrhagic). They look similar but are treated very differently.

Symptoms and why they happen — remember FAST

F — Face: drooping on one side.
A — Arms: weakness or numbness, often one-sided.
S — Speech: slurred, garbled, or trouble understanding.
T — Time: act fast and call emergency services.
Other signs: sudden vision loss, severe dizziness or loss of balance, and a sudden severe headache.

Causes and risk factors

High blood pressure (the biggest factor)
Atrial fibrillation (an irregular heartbeat that forms clots)
Diabetes, high cholesterol, smoking
Narrowing of the neck (carotid) arteries
Increasing age and family history

How it's diagnosed

An urgent brain scan (CT or MRI) is essential to tell an ischemic stroke from a bleed — because the treatments are opposite. Further imaging of the blood vessels locates the blockage, and tests look for the cause (heart rhythm, carotid arteries, blood sugar and cholesterol).

Diagram of the FAST stroke warning signs: facial drooping, arm weakness, slurred speech, and a clock for time. — The FAST signs — Face droop, Arm weakness, Speech difficulty, Time to call — catch most strokes early, when treatment works best.

Treatment and management

For ischemic stroke caught early, clot-busting medication (thrombolysis) can dissolve the clot, and thrombectomy — physically removing a large clot via a catheter — can restore flow to part of the brain. Both are highly time-dependent. Afterwards, treatment focuses on preventing the next stroke (blood thinners or antiplatelets, blood-pressure control) and rehabilitation to recover lost function.

Possible complications

Lasting weakness, speech or swallowing difficulty, and cognitive or emotional changes, depending on the area affected. Early rehabilitation improves recovery.

Prevention and outlook

Controlling blood pressure, treating atrial fibrillation, stopping smoking, and managing cholesterol and diabetes prevent most strokes. A brief warning episode (a TIA or 'mini-stroke') that fully resolves is still an emergency — it's a chance to prevent a major stroke. Outcomes vary widely, but fast treatment strongly improves them.

When to seek emergency care

Any sudden face droop, arm weakness, or speech difficulty — call emergency services immediately, even if it passes.
Sudden severe 'worst-ever' headache, sudden vision loss, or collapse.