6.3 Acute Stroke Recognition and Routing
Key Takeaways
- The Stroke Chain of Survival is rapid recognition, EMS activation, prehospital notification, transport to a stroke-capable center, and rapid in-hospital diagnosis and treatment.
- Use FAST (Face, Arm, Speech, Time) or BE-FAST (adding Balance and Eyes) to detect stroke; check glucose because hypoglycemia mimics stroke.
- Establish time last known well, which is the last time the patient was known to be normal, not when symptoms were discovered.
- A non-contrast CT must exclude hemorrhage before IV thrombolytics; alteplase or tenecteplase is given within 4.5 hours (some up to 24 h by perfusion imaging).
- Target door-to-CT within 25 minutes and door-to-needle at most 60 minutes; mechanical thrombectomy can extend to 24 hours in selected large-vessel occlusions.
6.3 The Acute Stroke Chain and Algorithm
Stroke care is about speed and routing. Time is brain: roughly 1.9 million neurons die each minute an ischemic stroke goes untreated. The Stroke Chain of Survival links each step: (1) rapid recognition of symptoms and EMS activation, (2) rapid EMS dispatch and prioritized transport, (3) prehospital notification of the receiving hospital, (4) transport to a stroke-capable center, and (5) rapid in-hospital diagnosis and treatment.
Recognition: FAST and BE-FAST
Use a validated screen. FAST = Face droop, Arm drift, Speech difficulty, Time to call EMS. BE-FAST adds Balance (sudden loss of coordination) and Eyes (sudden vision loss or double vision) to catch posterior-circulation strokes that FAST misses. The Cincinnati Prehospital Stroke Scale tests three of these: facial droop, arm drift, and abnormal speech; any single abnormality raises stroke probability sharply.
Time last known well
Eligibility for reperfusion hinges on last known well (LKW) - the last time the patient was verified neurologically normal, not the time symptoms were noticed. A patient who wakes with deficits at 7 AM but was normal at 10 PM has an LKW of 10 PM. Wake-up and unknown-onset strokes may still qualify for treatment based on advanced perfusion or MRI imaging.
Rule out the mimics
Check a blood glucose immediately - hypoglycemia is the classic stroke mimic and is instantly reversible. Other mimics include seizure with Todd paralysis, complex migraine, and intoxication. Screening for mimics must not delay stroke-team activation or imaging.
In-hospital time goals and the CT decision point
The AHA/ASA stroke algorithm sets aggressive door-to-event targets so the team moves in parallel, not in sequence.
| Step | Target from ED arrival |
|---|---|
| Door to physician/stroke team | <= 10 min |
| Door to non-contrast CT (scan started) | <= 25 min |
| Door to CT read | <= 45 min |
| Door to needle (IV thrombolytic) | <= 60 min |
The pivotal branch point is the non-contrast head CT. It answers one question: is there blood? Hemorrhagic stroke (intracerebral or subarachnoid hemorrhage) is an absolute contraindication to thrombolytics - giving a clot-buster would dissolve the clots limiting the bleed and likely be fatal.
Reperfusion: thrombolysis and thrombectomy
For ischemic stroke with no hemorrhage and no other contraindication, give an IV thrombolytic - alteplase 0.9 mg/kg (max 90 mg) or tenecteplase 0.25 mg/kg (max 25 mg) - within 4.5 hours of last known well. Newer trial data support tenecteplase in selected patients out to 24 hours when guided by perfusion imaging. Mechanical thrombectomy for a confirmed large-vessel occlusion can be performed up to 24 hours from LKW in carefully selected patients (DAWN/DEFUSE-3 perfusion-mismatch criteria). Blood pressure management before thrombolysis aims for below 185/110 mmHg.
Common traps
- Using the time symptoms were discovered instead of last known well.
- Forgetting the bedside glucose in a patient with altered mental status.
- Waiting to see whether deficits improve before activating the stroke system.
- Giving thrombolytics before the non-contrast CT excludes hemorrhage.
Scenario anchor
A patient has sudden left facial droop, arm drift, and slurred speech that began 90 minutes ago; glucose is 110 mg/dL. EMS pre-notifies the stroke center, the team meets the patient at the door, CT at 20 minutes shows no blood, and tenecteplase is given at 52 minutes - inside both the 4.5-hour window and the 60-minute door-to-needle goal.
Stroke Types, Severity, and Blood-Pressure Rules
Two broad categories
- Ischemic stroke (about 87%): a clot blocks a cerebral artery. Treatable with IV thrombolytics and/or thrombectomy.
- Hemorrhagic stroke (about 13%): a vessel ruptures - intracerebral hemorrhage (ICH) or subarachnoid hemorrhage (SAH). SAH classically presents as a "thunderclap" headache (sudden, worst-ever, maximal within seconds), often with neck stiffness and vomiting. Thrombolytics are absolutely contraindicated.
The whole reason for the urgent non-contrast CT is to separate these two before any clot-directed therapy.
Measuring severity
The National Institutes of Health Stroke Scale (NIHSS) quantifies deficit severity (0 = no deficit; higher scores = worse). It guides decisions and triage: a high NIHSS suggests a large-vessel occlusion (LVO) that may benefit from mechanical thrombectomy, often routed to a comprehensive stroke center. Prehospital LVO screens (such as RACE or LAMS) help EMS choose the right destination.
Blood pressure management
| Situation | Blood-pressure rule |
|---|---|
| Before IV thrombolysis | Lower to < 185/110 mmHg before giving the drug |
| After IV thrombolysis (first 24 h) | Keep < 180/105 mmHg |
| Ischemic stroke, not getting lytics | Permissive hypertension; generally do not treat unless > 220/120 mmHg |
| Hemorrhagic stroke | Carefully lower per ICH protocol to limit hematoma expansion |
Aggressively dropping the pressure in an untreated ischemic stroke can extend the infarct by reducing perfusion to the ischemic penumbra, which is why permissive hypertension is the rule unless extreme.
After thrombolysis
Watch for the major complication - symptomatic intracranial hemorrhage - with frequent neuro checks and blood-pressure control; a sudden decline, new headache, or vomiting warrants stopping any infusion and repeat imaging. Avoid antiplatelets/anticoagulants for 24 hours post-lysis until a follow-up CT excludes bleeding. The exam emphasis stays on the front end: recognize fast, fix the last-known-well time, exclude hemorrhage, and treat inside the window.
A non-contrast head CT in a patient with acute neurologic deficits shows a large intracerebral hemorrhage. The family asks for a clot-busting drug. What is correct?
Which letters does the BE-FAST stroke screen add beyond the original FAST mnemonic?
A patient was last known well at 10 PM and woke at 6 AM with weakness. The standard IV thrombolytic window measured from last known well is generally up to:
What is the AHA/ASA target door-to-needle time for IV thrombolytic administration in acute ischemic stroke?