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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- First test is noncontrast head CT to exclude hemorrhage before reperfusion therapy
- IV thrombolysis is considered for disabling ischemic stroke within 4.5 hours if no contraindications
- Large vessel occlusion may require mechanical thrombectomy, including selected patients up to 24 hours
- Do not acutely lower BP unless >220/120, or >185/110 if thrombolysis is planned
- Secondary prevention depends on mechanism: antiplatelet for noncardioembolic stroke, anticoagulation for atrial fibrillation
Overview
Ischemic stroke is acute neurological injury from interrupted arterial blood flow to the brain, retina, or spinal cord. Major mechanisms include large artery atherosclerosis, cardioembolism, small vessel disease, dissection, hypercoagulability, and less common vasculitic or paradoxical embolic causes. On USMLE Step 2 CK, the key decisions are time last known well, CT exclusion of hemorrhage, eligibility for thrombolysis, presence of a large vessel occlusion, and secondary prevention strategy.
Epidemiology
Most strokes in the United States are ischemic. Major risk factors include hypertension, diabetes, smoking, atrial fibrillation, hyperlipidemia, carotid stenosis, prior TIA or stroke, obstructive sleep apnea, obesity, and sedentary lifestyle. Cardioembolic strokes classically produce cortical findings such as aphasia, neglect, gaze deviation, or visual field loss.
Clinical Features
Symptoms
Sudden unilateral weakness or numbness affecting face, arm, or leg
Aphasia, dysarthria, visual field loss, diplopia, or acute confusion
Ataxia, vertigo, dysphagia, or crossed brainstem symptoms in posterior circulation stroke
Monocular curtain-like vision loss can reflect retinal ischemia
Wake-up stroke or unknown onset requires last-known-well timing and often advanced imaging
Headache may occur but severe thunderclap headache should raise concern for hemorrhage
Signs
Contralateral upper motor neuron weakness, hyperreflexia, or Babinski sign
MCA stroke: face/arm weakness greater than leg, aphasia if dominant, neglect if nondominant
ACA stroke: leg weakness greater than arm, abulia, urinary incontinence
PCA stroke: contralateral homonymous hemianopia, visual agnosia, thalamic sensory symptoms
Cerebellar or brainstem signs require urgent posterior circulation evaluation
Investigations
First-line
Noncontrast CT headFirst-line test to exclude hemorrhage; early ischemic signs may be subtle
Point-of-care glucoseHypoglycemia is a common stroke mimic and must be corrected immediately
NIH Stroke ScaleQuantifies deficit severity and supports reperfusion decisions
CTA head and neckIdentifies large vessel occlusion, carotid disease, vertebral disease, and dissection
Second-line
MRI brain with DWIMost sensitive for acute infarction, especially posterior fossa and small lacunar strokes
CT or MRI perfusionUsed for extended-window or unknown-onset stroke to identify salvageable tissue
ECG and telemetryDetect atrial fibrillation, MI, conduction disease, or cardioembolic source
Basic labsCBC, BMP, coagulation tests, troponin, lipid panel, HbA1c; do not delay thrombolysis unless clinically necessary
Specialist
EchocardiographyTTE or TEE for thrombus, valvular disease, PFO, atrial myxoma, or endocarditis
Carotid imagingDuplex, CTA, or MRA for extracranial carotid stenosis
Hypercoagulable/vasculitis testingSelected young or recurrent unexplained stroke patients
1
Immediate stabilization
- Activate stroke protocol and establish last known well time
- Airway, breathing, circulation; oxygen only if hypoxemic
- Check glucose and treat hypoglycemia immediately
- Keep NPO until swallow screen; use aspiration precautions
2
Reperfusion therapy
- IV alteplase or tenecteplase for eligible disabling stroke within 4.5 hours
- BP must be <185/110 before thrombolysis and <180/105 afterward
- Mechanical thrombectomy for eligible anterior circulation large vessel occlusion
- Do not delay thrombectomy to observe response after thrombolysis
3
Blood pressure/supportive care
- No thrombolysis: permissive hypertension unless BP >220/120
- If BP treatment needed, reduce by about 15% in first 24 hours
- Treat fever, hypoxia, severe hyperglycemia, and aspiration risk
- Intermittent pneumatic compression for DVT prevention early
4
Secondary prevention
- Antiplatelet therapy for noncardioembolic stroke
- Short-course aspirin plus clopidogrel for minor stroke/high-risk TIA when appropriate
- Oral anticoagulation for atrial fibrillation-related stroke when safe
- High-intensity statin and aggressive vascular risk-factor management
Complications
- Hemorrhagic transformation: Higher risk with large infarcts, thrombolysis, uncontrolled hypertension, and cardioembolism
- Cerebral edema: Malignant MCA infarction may require decompressive hemicraniectomy
- Aspiration pneumonia: Prevent with swallow screening
- Seizures: More likely with cortical infarcts
- Recurrent stroke: Highest early after TIA or minor stroke
USMLE Step 2 CK Exam Tips
- 1Sudden focal deficit = noncontrast CT first, not MRI
- 2Always check bedside glucose before thrombolysis
- 3Thrombolysis window is 4.5 hours; thrombectomy can extend to 24 hours in selected LVO patients
- 4BP threshold before thrombolysis is <185/110
- 5MCA = face/arm weakness and aphasia or neglect; ACA = leg weakness; PCA = homonymous hemianopia
- 6AF-related stroke prevention requires anticoagulation, not aspirin
- 7Symptomatic carotid stenosis 70-99% = carotid endarterectomy if operative risk acceptable
practicetest your knowledge on ischemic strokeApply what you've learnt with USMLE Step 2 CK-style questions from the iatroX Q-Bank — neurology and beyond.
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