USMLE Step 1 Stroke practice questions
Stroke is a sudden focal neurologic deficit caused by disruption of cerebral blood flow, either ischemic (~85% of cases, due to thrombosis, embolism, small-vessel lipohyalinosis, or global hypoperfusion) or hemorrhagic (~15%, due to vessel rupture). USMLE Step 1 emphasizes correlating vascular territory with clinical deficit, the cellular mechanisms of ischemic neuronal injury, and the underlying vessel pathology (atherosclerosis, lipohyalinosis, cardioembolism, amyloid angiopathy) rather than acute management or drug selection.
A 68-year-old right-handed man is brought to the emergency department 45 minutes after his wife noticed he suddenly could not speak clearly and dropped a cup of coffee. He has a history of hypertension and atrial fibrillation and takes no anticoagulant medication. Examination shows nonfluent, effortful speech with relatively preserved comprehension, and dense weakness of the right face and arm with relative sparing of the right leg. CT of the head shows no hemorrhage. Which of the following arteries is most likely occluded in this patient?
Patient Information Age: 74 years | Gender: M, self-identified | Site of Care: emergency department History Reason for Visit/Chief Concern: "My left hand feels weak and clumsy." History of Present Illness: • 2-day history of gradually worsening left hand and arm weakness with mild dysarthria • No sensory loss, no visual change, no headache • Poorly controlled hypertension for 10 years, admits to inconsistent medication adherence Physical Examination BP: 178/104 mm Hg | Pulse: 78/min Examination shows pure motor hemiparesis of the left face, arm, and leg roughly equally, with no aphasia, neglect, or visual field cut. Diagnostic Studies MRI of the brain shows a 6-mm infarct in the posterior limb of the right internal capsule. Which of the following is the most likely underlying vascular pathology in this patient?
A 58-year-old woman is evaluated in the intensive care unit 3 days after being resuscitated from cardiac arrest that was complicated by approximately 20 minutes of severe hypotension before return of spontaneous circulation. She remains intubated. Once sedation is lifted, examination shows bilateral weakness that is most pronounced in the proximal upper and lower extremities, with relatively preserved hand strength, facial movement, and vision. MRI of the brain shows bilateral infarcts along the border zone between the anterior and middle cerebral artery territories. Which of the following is the most likely mechanism underlying these infarcts?
A 71-year-old man arrives at the emergency department 1 hour after the acute onset of left-sided weakness and slurred speech. Noncontrast CT of the head shows no hemorrhage, and imaging confirms an acute right middle cerebral artery territory ischemic stroke. In the ischemic penumbra surrounding the infarct core, which of the following is the most likely immediate mechanism contributing to ongoing neuronal injury?
An 82-year-old woman with a history of mild cognitive impairment is brought to the emergency department after her family found her acutely confused with new right-sided weakness. This is her third similar episode in the past 18 months; prior episodes were attributed to lobar hemorrhages in different locations on imaging, each of which resolved with residual mild deficits. Head CT now shows a hemorrhage centered in the left parietal lobe extending to the cortical surface, without involvement of the basal ganglia, thalamus, or brainstem. Her blood pressure is 128/78 mm Hg, and she has no history of hypertension. Which of the following is the most likely underlying vascular abnormality?
Stroke, answered
How much detail do I need on tPA and thrombectomy time windows for Step 1?
Very little. Step 1 does not test acute management specifics like thrombolytic time windows or thrombectomy eligibility — that content belongs to Step 2 CK. Focus instead on recognizing stroke syndromes, localizing the vascular lesion from the deficit pattern, and understanding the mechanisms of neuronal injury and underlying vessel pathology.
What is the fastest way to distinguish ACA, MCA, and PCA strokes on an exam question?
ACA occlusion causes leg-predominant weakness with possible urinary incontinence and abulia (medial frontal/paracentral lobule). MCA occlusion causes face/arm-predominant weakness with aphasia (if the dominant hemisphere is involved) or neglect (if the nondominant hemisphere is involved). PCA occlusion causes a contralateral homonymous hemianopia, often with macular sparing, because it supplies the occipital visual cortex.
Why do lacunar strokes not produce aphasia, neglect, or visual field cuts?
Lacunar infarcts occur in small subcortical structures — the internal capsule, thalamus, basal ganglia, or pons — supplied by small penetrating arteries, not the cerebral cortex itself. Because language, attention, and visual processing are cortical functions, they are preserved even when there is significant motor or sensory deficit.
How do I tell cerebral amyloid angiopathy apart from a hypertensive hemorrhage on a vignette?
Cerebral amyloid angiopathy classically causes recurrent lobar hemorrhages in normotensive or well-controlled elderly patients, often with coexisting cognitive impairment. Hypertensive hemorrhage instead favors deep structures — basal ganglia, thalamus, pons, or cerebellum — in patients with a history of poorly controlled blood pressure.
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