Stroke

The answer first

Stroke is a syndrome of sudden onset neurological deficit caused by disruption of cerebral blood flow. It is a medical emergency where every minute of delay kills approximately 1.9 million neurons. The two questions that determine everything are: when was the patient last known well? and is there a large vessel occlusion? ^[1]

Acute ischaemic stroke (85% of all strokes) is potentially reversible with reperfusion therapy: ^[1]

1. IV thrombolysis — alteplase (or tenecteplase) within 4.5 hours of last-known-well. Earlier is better; the benefit curve is steep in the first 90 minutes and flattens toward 4.5 hours.
2. Mechanical thrombectomy — for large vessel occlusion (internal carotid artery terminus, M1 middle cerebral artery, basilar artery) within 6 hours of onset, or up to 24 hours with imaging evidence of salvageable penumbra (DAWN/DEFUSE-3 criteria). ^[1]

The organising principle is "time is brain." Every minute of delayed reperfusion means less salvageable tissue. The non-contrast CT may be normal in the first hours — a normal CT does not exclude acute stroke; it excludes haemorrhage. ^[1]

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References12ShowHide

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