You’re cruising through your neuro q-bank and hit the classic: “acute focal deficits, CT head is negative, what now?” Stroke management questions love to hide time windows, contraindications, and the one detail that flips you from IV thrombolysis to thrombectomy—or to “do not lysis.” This post walks through a representative vignette, nails the correct answer, then dissects the most common distractors so you stop losing points to tempting-but-wrong choices.
Tag: Neurology > Stroke & Cerebrovascular
The Clinical Vignette
A 67-year-old man with hypertension and hyperlipidemia is brought to the ED for sudden right facial droop and right arm weakness. Last known well was 70 minutes ago. He is awake but has expressive aphasia. Vitals: BP 178/96, HR 82, RR 16, O₂ sat 98% RA, glucose 110 mg/dL. Neuro exam suggests a left hemispheric stroke; NIHSS is 12.
Noncontrast CT head shows no hemorrhage and no large established infarct. CT angiography shows an M1 segment left MCA occlusion.
Question: What is the best next step in management?
Answer choices:
A. Start aspirin immediately
B. Administer IV alteplase (tPA)
C. Administer IV alteplase and proceed with mechanical thrombectomy
D. Start IV heparin infusion
E. Lower blood pressure aggressively to <140/90 before any reperfusion therapy
F. Give mannitol for presumed increased intracranial pressure
G. Carotid endarterectomy today
Step-by-Step: What Matters in the Stem?
1) Is this ischemic vs hemorrhagic?
- Noncontrast CT head is the first imaging test to rule out hemorrhage.
- CT is normal early in ischemic stroke—this does not rule it out.
2) Time window
- Last known well: 70 minutes → within the standard IV alteplase window (≤4.5 hours).
3) Is there a large vessel occlusion (LVO)?
- CTA: M1 MCA occlusion → yes, classic LVO → think mechanical thrombectomy (in addition to IV alteplase if eligible).
Correct Answer: C. Administer IV alteplase and proceed with mechanical thrombectomy
Why this is correct (the high-yield algorithm)
In an eligible patient with acute ischemic stroke:
- Give IV alteplase if within window and no contraindications
- Do not delay thrombectomy for tPA when an LVO is present
- Mechanical thrombectomy is indicated for anterior circulation LVO (ICA/M1 proximal MCA) within:
- 0–6 hours for many patients, and
- up to 24 hours for select patients with favorable perfusion imaging (DAWN/DEFUSE-3 concept—testable as “salvageable penumbra”).
Key tPA eligibility anchors (USMLE-style)
- Indication: disabling neurologic deficit + ischemic stroke suspected + CT head excludes hemorrhage + within ≤4.5 hours of last known well.
- Don’t forget: check fingerstick glucose (hypoglycemia can mimic stroke).
Thrombectomy anchors
- Best candidates: proximal anterior circulation LVO (ICA, M1) with disabling deficit.
- Imaging: CTA/MRA identifies LVO; perfusion imaging may guide late window selection.
Why Each Distractor Is Wrong (and when it might be right)
A. Start aspirin immediately
Why it’s wrong here:
- If you’re giving alteplase, you generally delay antiplatelets for 24 hours and repeat imaging to exclude hemorrhage.
When aspirin is right:
- Ischemic stroke or TIA not treated with tPA, start antiplatelet therapy early (often within 24 hours).
- Minor non-cardioembolic stroke/TIA may get dual antiplatelet therapy short-term (institution/guideline dependent), but this is Step 2-level nuance.
B. Administer IV alteplase (tPA)
Why it’s incomplete:
- He has an M1 occlusion → thrombectomy improves outcomes and should be pursued.
- You do not choose between them as mutually exclusive (in eligible patients). Think “bridge therapy”: tPA + thrombectomy.
When B would be correct:
- No LVO on CTA, or thrombectomy not available, but still within tPA window and eligible.
D. Start IV heparin infusion
Why it’s wrong:
- Routine anticoagulation in acute ischemic stroke does not improve outcomes and increases hemorrhagic transformation risk.
- Even in atrial fibrillation-associated stroke, you don’t reflexively heparinize in the ED.
When anticoagulation matters:
- Long-term secondary prevention for cardioembolic stroke (e.g., AF) — timing depends on infarct size/bleeding risk (often delayed days).
- Special situations (rare on Step): cerebral venous sinus thrombosis → anticoagulation even with hemorrhage can be indicated.
E. Lower blood pressure aggressively to <140/90 before any reperfusion therapy
Why it’s wrong (and dangerous):
- Overly aggressive BP reduction can decrease cerebral perfusion to the ischemic penumbra.
What you should know instead (high-yield BP thresholds):
- If tPA candidate: BP must be <185/110 before thrombolysis and maintained <180/105 after.
- If not receiving tPA: permissive hypertension is often allowed up to about 220/120 (unless other end-organ emergencies).
In this vignette, BP is 178/96, already acceptable for tPA—no need for aggressive lowering.
F. Give mannitol for presumed increased intracranial pressure
Why it’s wrong:
- No signs of impending herniation (e.g., declining mental status, blown pupil, Cushing triad).
- Early ischemic stroke management prioritizes reperfusion and supportive care.
When osmotherapy is right:
- Malignant cerebral edema (especially large MCA infarct), signs of elevated ICP/herniation → mannitol or hypertonic saline as bridge to definitive management.
G. Carotid endarterectomy today
Why it’s wrong:
- The occlusion is intracranial (M1), not an extracranial carotid stenosis problem.
- Even when carotid endarterectomy is indicated, it’s not the immediate ED move in a hyperacute LVO scenario.
When carotid endarterectomy is right:
- Symptomatic carotid stenosis (classically severe, e.g., 70–99%) after stabilization; timing depends on severity and local practice (often within days for appropriate candidates).
High-Yield Stroke Reperfusion Cheat Sheet
| Concept | High-yield takeaway |
|---|---|
| First imaging | Noncontrast CT head to rule out hemorrhage |
| IV alteplase window | ≤4.5 hours from last known well (if eligible) |
| BP requirement for tPA | Must be <185/110 before tPA; maintain <180/105 after |
| LVO identification | CTA/MRA shows ICA/M1 occlusion → think thrombectomy |
| Thrombectomy window | ≤6 hours routinely; up to 24 hours in select patients with salvageable tissue |
| Antiplatelets after tPA | Hold for 24 hours, then repeat imaging |
| Heparin drip | Not routine in acute ischemic stroke |
Classic “Gotchas” USMLE Loves
1) “CT is normal—so it’s not a stroke”
Wrong. Early ischemic strokes can have normal noncontrast CT. CT is to rule out hemorrhage.
2) “Wait for MRI before giving tPA”
No. Don’t delay time-sensitive reperfusion therapy for MRI if the presentation fits and CT excludes bleed.
3) “Seizure at onset means no tPA”
A seizure at onset isn’t an absolute exclusion if deficits are believed due to stroke rather than postictal paralysis—test writers may use this to see if you can reason clinically.
4) BP management is conditional
- tPA candidate: treat BP to threshold.
- Not tPA: permissive hypertension (unless contraindicated).
Quick Pattern Recognition: What the Test Wants You to Say
If you see:
- Disabling deficits
- Last known well within 4.5 hours
- CT negative for hemorrhage
- CTA shows proximal MCA/ICA occlusion
Your brain should autopilot to: IV alteplase (if eligible) + mechanical thrombectomy.