USMLE Step 1 & 2 Stroke: Ischemic and Hemorrhagic
Last updated: May 2, 2026
Stroke: Ischemic and Hemorrhagic questions are one of the highest-leverage areas to study for the USMLE Step 1 & 2. This guide breaks down the rule, the elements you need to recognize, the named traps that catch most students, and a memory aid that scales to test day. Read it once, then practice the same sub-topic adaptively in the app.
The rule
A stroke is a sudden focal neurologic deficit caused by either vessel occlusion (ischemic, ~85%) or vessel rupture (hemorrhagic, ~15%). Your first job on every stroke vignette is to get a non-contrast head CT to separate the two, because the acute treatments are opposite: ischemic strokes get reperfusion (tPA and/or thrombectomy) while hemorrhagic strokes get blood-pressure control, reversal of anticoagulation, and neurosurgical evaluation. Your second job is to localize — the deficit pattern tells you which vascular territory is involved and predicts what imaging and intervention you need.
Elements breakdown
Ischemic — large-artery atherothrombotic
Plaque rupture in carotid or intracranial vessel triggers thrombosis
- carotid bruit, prior TIA, atherosclerosis risk factors
- stuttering or stepwise onset
- cortical signs match a single arterial territory
Common examples:
- MCA stem occlusion from internal carotid plaque
- basilar thrombosis on top of vertebrobasilar atherosclerosis
Ischemic — cardioembolic
Embolus from heart lodges in a cerebral artery
- sudden, maximal-at-onset deficit
- atrial fibrillation, recent MI, mechanical valve, endocarditis
- may involve multiple vascular territories simultaneously
Common examples:
- MCA embolus in afib patient off anticoagulation
- septic embolus in IV drug user with mitral endocarditis
Ischemic — small-vessel lacunar
Lipohyalinosis of penetrating arterioles in chronically hypertensive patients
- pure motor, pure sensory, ataxic-hemiparesis, or dysarthria-clumsy-hand
- no cortical signs (no aphasia, neglect, visual-field cut)
- internal capsule, pons, thalamus, basal ganglia
Common examples:
- pure motor hemiparesis from posterior limb internal capsule infarct
- pure sensory stroke from VPL thalamic lacune
Hemorrhagic — intracerebral (ICH)
Rupture of small penetrating artery into brain parenchyma
- headache, vomiting, decreased consciousness more prominent than ischemic
- hypertensive bleeds: basal ganglia (putamen), thalamus, pons, cerebellum
- lobar bleeds in elderly: think cerebral amyloid angiopathy
Common examples:
- putaminal hemorrhage in poorly controlled hypertensive
- occipital lobar bleed in 82-year-old with prior similar episodes
Hemorrhagic — subarachnoid (SAH)
Saccular (berry) aneurysm rupture into subarachnoid space
- thunderclap 'worst headache of life', meningismus, often brief LOC
- CT shows blood in basal cisterns, sylvian fissure
- if CT negative within 6 h and suspicion remains: LP for xanthochromia
Common examples:
- sudden severe headache during exertion in 50-year-old smoker
- ADPKD or Ehlers-Danlos patient with sentinel headache
Anterior circulation territories
Carotid system supplying frontal/parietal/temporal cortex
- MCA: contralateral face/arm > leg weakness, aphasia (dominant) or neglect (non-dominant)
- ACA: contralateral leg > arm weakness, abulia, urinary incontinence
- ICA: combined MCA+ACA picture, sometimes ipsilateral monocular blindness (amaurosis fugax)
Posterior circulation territories
Vertebrobasilar system supplying brainstem, cerebellum, occipital lobes
- PCA: contralateral homonymous hemianopia with macular sparing, alexia without agraphia
- cerebellar: ipsilateral ataxia, dysmetria, vertigo, vomiting
- brainstem: crossed signs (ipsilateral cranial nerve + contralateral body), diplopia, dysarthria, dysphagia
Common examples:
- lateral medullary (Wallenberg): ipsilateral Horner, facial sensory loss, contralateral body sensory loss
- locked-in syndrome from basilar thrombosis
Common patterns and traps
The CT-First Reflex
USMLE will tempt you with a vignette that screams 'ischemic stroke' and ask for the next best step. The right answer is almost always non-contrast head CT before any thrombolytic, antiplatelet, or anticoagulant decision. Treatments diverge so completely between ischemic and hemorrhagic stroke that you cannot pick one without imaging.
A 'next best step' answer that proposes IV alteplase, aspirin, or heparin without first ruling out hemorrhage on CT.
The Cortical-Versus-Lacunar Tell
Whether the patient has cortical signs (aphasia, neglect, gaze deviation, homonymous hemianopia) versus a 'pure' deficit (motor only, sensory only) is the single best clue to mechanism. Cortical signs push you toward large-artery or cardioembolic etiology with carotid Doppler and echo; pure syndromes point to lacunar disease from chronic hypertension and diabetes.
A vignette emphasizing pure motor hemiparesis with no language or visual deficits, where the wrong answer orders an urgent carotid endarterectomy workup instead of optimizing BP and statin therapy.
Thunderclap Means SAH Until Proven Otherwise
A sudden, maximal-at-onset 'worst headache of life,' especially with brief loss of consciousness, neck stiffness, or vomiting, is subarachnoid hemorrhage from a ruptured berry aneurysm until imaging says otherwise. Non-contrast CT is the first test; if it is negative and suspicion remains, lumbar puncture for xanthochromia is the next step, not MRI.
A distractor that orders MRI brain or empiric migraine treatment for a thunderclap headache instead of CT followed by LP.
The Posterior Circulation Decoy
Posterior strokes hide because they don't always cause hemiparesis or aphasia. Vertigo, diplopia, dysarthria, dysphagia, ataxia, and crossed cranial-nerve-plus-body-sensory deficits are the giveaways. Missing a basilar or cerebellar stroke is high-yield because the test rewards recognizing brainstem syndromes (Wallenberg, locked-in) and the catastrophic consequences of cerebellar swelling.
A vignette of acute vertigo, vomiting, and gait ataxia in a vasculopath where the wrong answer is 'benign positional vertigo, prescribe meclizine' instead of urgent posterior-fossa imaging.
The Anticoagulation Reversal Pivot
When a patient on warfarin, a DOAC, or heparin presents with new neurologic deficit and CT shows hemorrhage, the test is checking whether you reverse the anticoagulant: 4-factor PCC plus IV vitamin K for warfarin, idarucizumab for dabigatran, andexanet alfa (or PCC) for apixaban/rivaroxaban, protamine for heparin. Continuing or 'holding' the anticoagulant is wrong; active reversal is the answer.
A wrong-answer choice that 'holds warfarin and rechecks INR in 12 hours' for an INR-9 patient with an acute lobar hemorrhage on CT.
How it works
Picture Mr. Reyes, a 68-year-old with hypertension and atrial fibrillation, found at 9:00 AM with right face-and-arm weakness and inability to speak fluently. The deficit pattern (face/arm > leg, expressive aphasia) localizes to the dominant left MCA. Last-known-well was 7:30 AM, so you are inside the 4.5-hour tPA window. The non-contrast CT is your fork in the road: if it shows no hemorrhage, you give IV alteplase (assuming no contraindications) and call interventional neuroradiology for possible thrombectomy because a proximal MCA occlusion is a large-vessel target out to 24 hours in selected patients. If instead the CT showed a hyperdense putaminal hemorrhage, you would pivot completely — lower the BP to a systolic target around 140, reverse any anticoagulation, and consult neurosurgery. Same patient, same deficit, opposite drugs.
Worked examples
Which of the following is the most appropriate next step in management?
- A Administer IV alteplase, then transfer for mechanical thrombectomy
- B Administer IV alteplase only; thrombectomy is not indicated for M1 occlusion
- C Withhold alteplase due to recent apixaban use and proceed directly to mechanical thrombectomy ✓ Correct
- D Start aspirin 325 mg and admit for stroke unit observation
Why C is correct: This is a large-vessel (M1) occlusion within the thrombectomy window with a disabling deficit (NIHSS 18), so endovascular thrombectomy is indicated. However, IV alteplase is contraindicated because she took a direct oral anticoagulant (apixaban) within the last 48 hours without a reversal agent and without coagulation parameters confirming clearance. The right move is to skip thrombolytics and proceed directly to mechanical thrombectomy, which has independent benefit and no DOAC contraindication.
Why each wrong choice fails:
- A: Alteplase is contraindicated because of apixaban within 48 hours; giving it would dramatically raise the risk of symptomatic intracerebral hemorrhage. Thrombectomy alone is the answer. (The Anticoagulation Reversal Pivot)
- B: Mechanical thrombectomy is exactly what is indicated for an M1 occlusion with a disabling deficit inside the window. This choice has the contraindication right but the procedure wrong. (The CT-First Reflex)
- D: Aspirin alone for a large-vessel occlusion with NIHSS 18 inside the thrombectomy window abandons the most beneficial intervention available. Aspirin is appropriate after reperfusion or when reperfusion is not an option, not in place of it. (The Cortical-Versus-Lacunar Tell)
Which of the following is the most appropriate next step in management?
- A Administer IV alteplase within the 4.5-hour window
- B Lower systolic blood pressure to a target of approximately 140 mm Hg with IV nicardipine ✓ Correct
- C Begin a heparin infusion to prevent infarct extension
- D Obtain CT angiography to evaluate for mechanical thrombectomy candidacy
Why B is correct: The CT shows an acute hypertensive intracerebral hemorrhage in the putamen, the classic location for chronic-hypertension-related bleeds from ruptured lenticulostriate arteries. Acute management centers on lowering systolic BP to roughly 140 mm Hg using titratable IV agents (nicardipine, clevidipine, labetalol), which reduces hematoma expansion without dropping cerebral perfusion catastrophically. Reversing any anticoagulation and neurosurgical consultation come next.
Why each wrong choice fails:
- A: Alteplase is absolutely contraindicated in intracerebral hemorrhage — giving it would catastrophically expand the bleed. The CT specifically rules this option out. (The CT-First Reflex)
- C: Heparin in an active intracerebral hemorrhage will worsen the bleed. Anticoagulants and antiplatelets are held in ICH, not started. (The Anticoagulation Reversal Pivot)
- D: Thrombectomy treats a clot, not a bleed. CTA may be obtained later to evaluate for an underlying vascular malformation, but it is not the next step over BP control in an actively expanding hypertensive ICH. (The CT-First Reflex)
Occlusion of which of the following arteries best explains this patient's findings?
- A Left posterior inferior cerebellar artery (PICA) ✓ Correct
- B Left middle cerebral artery (MCA)
- C Left anterior spinal artery
- D Left anterior inferior cerebellar artery (AICA)
Why A is correct: This is lateral medullary syndrome (Wallenberg): ipsilateral Horner (ptosis, miosis), ipsilateral facial pain/temperature loss with contralateral body pain/temperature loss (crossed sensory loss), ipsilateral cerebellar ataxia, vertigo, dysphagia, hoarseness from nucleus ambiguus involvement, and absence of significant limb weakness because the corticospinal tract is spared. PICA occlusion (or vertebral artery occlusion supplying PICA territory) is the classic vascular cause.
Why each wrong choice fails:
- B: MCA occlusion produces contralateral face/arm > leg weakness, cortical sensory loss, and aphasia (if dominant) or neglect — none of which fit this brainstem-and-cerebellar picture. The preserved limb strength alone rules out a major MCA stroke. (The Posterior Circulation Decoy)
- C: Anterior spinal artery medial medullary syndrome produces contralateral arm and leg weakness (corticospinal), contralateral position/vibration loss (medial lemniscus), and ipsilateral tongue deviation (CN XII). It does not cause the cerebellar ataxia, Horner syndrome, or crossed spinothalamic loss seen here. (The Posterior Circulation Decoy)
- D: AICA occlusion (lateral pontine syndrome) shares vertigo and ipsilateral Horner with Wallenberg but is distinguished by ipsilateral facial paralysis (CN VII nucleus) and ipsilateral hearing loss (cochlear nucleus / labyrinthine artery). This patient has neither facial weakness nor hearing loss, pointing instead to PICA. (The Posterior Circulation Decoy)
Memory aid
FAST gets the patient to you (Face, Arm, Speech, Time); once they're in the door, run 'CT first, clock second, clot or bleed third.' For lacunar syndromes remember the four pure pictures: pure motor, pure sensory, ataxic-hemiparesis, dysarthria-clumsy-hand — none of them have cortical signs.
Key distinction
Lacunar (small-vessel) versus cortical (large-artery or embolic) is the highest-yield distinction because it changes the workup. Lacunar = no aphasia, no neglect, no visual-field cut → control BP and lipids, manage diabetes; you do not need carotid Doppler or echo with the same urgency. Cortical signs → carotid imaging and echocardiogram are mandatory because you must find the embolic source.
Summary
Every stroke question is a two-step problem: separate ischemic from hemorrhagic with non-contrast CT, then localize by deficit pattern to pick the right acute treatment and workup.
Practice stroke: ischemic and hemorrhagic adaptively
Reading the rule is the start. Working USMLE Step 1 & 2-format questions on this sub-topic with adaptive selection, watching your mastery score climb in real time, and seeing the items you missed return on a spaced-repetition schedule — that's where score lift actually happens. Free for seven days. No credit card required.
Start your free 7-day trialFrequently asked questions
What is stroke: ischemic and hemorrhagic on the USMLE Step 1 & 2?
A stroke is a sudden focal neurologic deficit caused by either vessel occlusion (ischemic, ~85%) or vessel rupture (hemorrhagic, ~15%). Your first job on every stroke vignette is to get a non-contrast head CT to separate the two, because the acute treatments are opposite: ischemic strokes get reperfusion (tPA and/or thrombectomy) while hemorrhagic strokes get blood-pressure control, reversal of anticoagulation, and neurosurgical evaluation. Your second job is to localize — the deficit pattern tells you which vascular territory is involved and predicts what imaging and intervention you need.
How do I practice stroke: ischemic and hemorrhagic questions?
The fastest way to improve on stroke: ischemic and hemorrhagic is targeted, adaptive practice — working questions that focus on your specific weak spots within this sub-topic, getting immediate feedback, and revisiting items you missed on a spaced-repetition schedule. Neureto's adaptive engine does this automatically across the USMLE Step 1 & 2; start a free 7-day trial to see your sub-topic mastery climb in real time.
What's the most important distinction to remember for stroke: ischemic and hemorrhagic?
Lacunar (small-vessel) versus cortical (large-artery or embolic) is the highest-yield distinction because it changes the workup. Lacunar = no aphasia, no neglect, no visual-field cut → control BP and lipids, manage diabetes; you do not need carotid Doppler or echo with the same urgency. Cortical signs → carotid imaging and echocardiogram are mandatory because you must find the embolic source.
Is there a memory aid for stroke: ischemic and hemorrhagic questions?
FAST gets the patient to you (Face, Arm, Speech, Time); once they're in the door, run 'CT first, clock second, clot or bleed third.' For lacunar syndromes remember the four pure pictures: pure motor, pure sensory, ataxic-hemiparesis, dysarthria-clumsy-hand — none of them have cortical signs.
What's a common trap on stroke: ischemic and hemorrhagic questions?
giving tPA before the head CT comes back
What's a common trap on stroke: ischemic and hemorrhagic questions?
treating a hypertensive ICH like ischemic stroke and permitting BP
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