Ischemic vs Hemorrhagic Stroke: Workup, Time Windows, and Management
Time is brain — literally. Every hour of untreated ischemic stroke destroys ~120 million neurons. Knowing the diagnostic algorithm and time windows is the difference between a functional patient and a devastating outcome.
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Progress Note Editorial · Evidence-based
Updated July 2026
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The 60-second version
CT head without contrast FIRST — differentiates ischemic from hemorrhagic
IV tPA within 3–4.5 hours of onset, BP must be <185/110 first
Never give tPA for hemorrhagic stroke or unknown onset time
Thrombectomy up to 24 hours for LVO in selected patients
SAH: CT first, then LP if negative — treat with nimodipine
Ischemic vs Hemorrhagic: First Differentiate
CT head without contrast is the first imaging in all strokes — differentiates hemorrhagic (hyperdense = white) from ischemic (initially normal, then hypodense over hours). Do NOT give tPA for hemorrhagic stroke. Most strokes (85%) are ischemic. Hemorrhagic signs: sudden onset worst headache of life (SAH), papilledema, vomiting, hypertensive emergency.
Ischemic Stroke: Time Windows
IV tPA (alteplase): within 3 hours of symptom onset (extended to 4.5 hours in selected patients without certain exclusions). Thrombectomy: within 24 hours for large vessel occlusion (LVO) in carefully selected patients with salvageable tissue. BP management before tPA: must be <185/110 mmHg. After tPA: keep <180/105 mmHg for 24 hours. If not tPA candidate: allow permissive hypertension up to 220/120.
tPA Contraindications (Tested Frequently)
Absolute: hemorrhage on CT, platelets <100K, INR >1.7, heparin use with elevated aPTT, major surgery in last 14 days, prior intracranial hemorrhage, BP >185/110 uncontrolled, recent head trauma/stroke in past 3 months, blood glucose <50 or >400. Relative: mild improving symptoms, seizure at onset, pregnancy, history of prior stroke + diabetes.
Hemorrhagic Stroke Management
SAH: non-contrast CT (sensitive in first 24h), then LP if CT negative (xanthochromia). Treat: nimodipine (prevents vasospasm, improves outcomes), maintain euvolemia, avoid hypotension, neurosurgical consult. ICH: reverse anticoagulation immediately (4-factor PCC for warfarin, idarucizumab for dabigatran, andexanet alfa for Xa inhibitors). BP target: systolic 140 mmHg. Neurosurgery consult for large/surgical lesions.
Test yourself
Quick check — 3 questions
1. A 68-year-old presents at 3:20 AM with left hemiplegia. Last seen normal 11 PM. CT shows no hemorrhage. Is IV tPA indicated?
Explanation. Stroke onset = last known well (11 PM). Current time is 3:20 AM = 4h 20m since last known well, which exceeds the 4.5-hour standard window. Additionally, wake-up strokes require imaging-based selection (DWI/FLAIR mismatch) for extended window tPA — standard IV tPA is not appropriate here without further MRI evaluation.
2. A stroke patient eligible for tPA has BP 192/104 on arrival. The next step is:
Explanation. BP must be ≤185/110 before tPA administration. Administer labetalol 10–20 mg IV or nicardipine drip to achieve this. Once BP is controlled, reassess the time window and eligibility. If BP cannot be reliably controlled below this threshold, tPA is contraindicated.
3. Subarachnoid hemorrhage is most commonly caused by:
Explanation. The most common cause of SAH is rupture of a saccular (berry) aneurysm, typically at arterial branch points of the Circle of Willis. Classic presentation: thunderclap 'worst headache of life,' meningismus, photophobia. Treat with nimodipine, neurosurgical or endovascular clipping/coiling.
Frequently asked questions
When is 'last known well' used in stroke management?
Stroke onset time is defined as 'last known well' — when the patient was last confirmed to be at baseline. For wake-up strokes (patient wakes with deficits), onset time is the last time they were seen normal before sleep. This is critical for tPA eligibility: if last known well was >4.5 hours ago, standard IV tPA is contraindicated. MRI-guided selection (DWI/FLAIR mismatch) can identify wake-up stroke patients who may benefit from thrombolysis.
What is the difference between TIA and stroke?
Traditionally, TIA was defined by symptom resolution within 24 hours. The modern definition (tissue-based): TIA = transient neurological symptoms with NO infarction on diffusion-weighted MRI. Stroke = brain infarction confirmed on MRI regardless of symptom duration. This matters because some clinically 'brief' events show DWI lesions and should be managed as stroke. ABCD2 score helps risk-stratify TIA for early stroke risk.
What is the target blood pressure in ischemic stroke before tPA?
For tPA eligibility, BP must be ≤185/110 mmHg before administration. Labetalol IV (10–20 mg) or nicardipine IV drip are the typical agents to lower BP acutely. If BP cannot be lowered below this threshold, tPA should be withheld. After tPA, maintain BP <180/105 for at least 24 hours to reduce hemorrhagic transformation risk.
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