Ischemic Stroke
Neurology
Illness script · Neurology
Ischemic Stroke
Sudden focal neurologic deficit from arterial occlusion causing cerebral infarction; accounts for ~87% of all strokes.
This illness script for Ischemic Stroke covers predisposing factors, classic presentation, mechanism, workup, management, and the clinical pivots that separate it from look-alikes—written for USMLE Step 1 and clerkship reasoning.
01
Predisposing factors
- HTN is #1 modifiable risk factor
- Atrial fibrillation → cardioembolic source (most common cardiac cause)
- Diabetes, hyperlipidemia, smoking accelerate atherosclerosis
- Carotid artery stenosis (large-vessel disease)
- Hypercoagulable states (antiphospholipid syndrome, OCP use)
- Age >55, male sex, Black race higher incidence
02
Presentation
- Sudden-onset, FOCAL, non-progressive neurologic deficits (maximal at onset if embolic)
- MCA territory (most common): contralateral hemiplegia, hemianesthesia, gaze deviation toward lesion
- Dominant MCA: aphasia; non-dominant MCA: hemispatial neglect
- PCA: contralateral homonymous hemianopia with macular sparing
- Posterior circulation (PICA): vertigo, dysphagia, ipsilateral Horner's, crossed deficits (lateral medullary/Wallenberg)
- Lacunar infarcts: pure motor, pure sensory, ataxic hemiparesis — no cortical signs
03
Pathophysiology
- Thrombotic or embolic occlusion → ischemic penumbra surrounds infarcted core
- Penumbra is salvageable tissue — time-sensitive reperfusion window
- Cytotoxic edema, glutamate excitotoxicity, neuronal death within minutes
- Cardioembolic strokes typically abrupt-onset maximal deficit; thrombotic may stutter
04
Diagnostics
- Non-contrast CT head FIRST (rules out hemorrhage before tPA)
- MRI DWI gold standard — detects infarct within minutes, CT may be normal <6 h
- CT angiography (CTA head/neck) identifies large-vessel occlusion (LVO) for thrombectomy
- ECG and prolonged cardiac monitoring to detect atrial fibrillation
- Fasting lipids, HbA1c, hypercoagulable workup in young or cryptogenic stroke
05
Management
- IV alteplase (tPA) within 4.5 h of symptom onset if no contraindications
- Mechanical thrombectomy up to 24 h for LVO (MCA, ICA, basilar) — superior to tPA alone
- Aspirin 325 mg within 24–48 h (not if tPA given within 24 h)
- BP permissive (allow up to 220/120) unless tPA given, then keep <180/105
- Anticoagulation for AF-related stroke; statins, antihypertensives for secondary prevention
06
Clinical pivots
How to separate this script from the look-alikes that show up on exams and on the wards.
Hemorrhagic Stroke
Non-contrast CT shows hyperdense (white) blood; tPA absolutely contraindicated
Complex/Hemiplegic Migraine
Prior identical episodes, headache prominent, deficits fully resolve; younger patient
Todd's Paralysis
Witnessed seizure precedes focal weakness; gradual resolution over hours
Hypoglycemia
Check glucose immediately — serum glucose <60 mg/dL corrects 'stroke' symptoms with dextrose
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Educational use only. This illness script is a study framework, not medical advice. Confirm decisions with current guidelines and your clinical supervisors.