Internal MedicineNeurologyIschemic Stroke

Ischemic Stroke

Must-Not-Miss / Red Flags

  • Hemorrhagic transformation: sudden deterioration after initial improvement
  • Malignant MCA infarction: cerebral edema leading to herniation
  • BP >220/120: contraindication for thrombolysis
Patient Explanation
“A blood vessel in your brain has become blocked, cutting off oxygen to part of the brain. We’ll act fast to restore blood flow and prevent permanent damage.”
Board Fact
“Time is brain: 1.9 million neurons die every minute during a large‑vessel occlusion.”
ICD-10
I63.9

Definition & Core Concept

Ischemic stroke is an acute neurological deficit caused by focal cerebral infarction due to occlusion of a cerebral artery, accounting for 87% of all strokes.

Epidemiology & Risk Factors

  • Second leading cause of death worldwide
  • Incidence: 795,000 strokes per year in the US
  • Risk factors: hypertension, atrial fibrillation, diabetes, smoking, carotid stenosis

Pathophysiology (Rule of 3)

  1. Arterial occlusion (thrombotic or embolic) → cessation of blood flow
  2. Ischemic core (irreversible damage) surrounded by ischemic penumbra (salvageable tissue)
  3. Excitotoxicity, oxidative stress, inflammation → neuronal death

Clinical Presentation

  • Sudden onset of focal neurological deficit: facial droop, arm weakness, speech difficulty
  • Contralateral hemiparesis, hemisensory loss, homonymous hemianopia (MCA territory)
  • Ataxia, vertigo, dysphagia (posterior circulation)

Diagnostic Workup

Non‑contrast CT head: rule out hemorrhage. CT angiography: identify large‑vessel occlusion. CT perfusion: identify penumbra. NIH Stroke Scale (NIHSS): quantify severity.

Management Protocol

  1. IV thrombolysis: Alteplase (tPA) 0.9 mg/kg within 4.5 hours of symptom onset
  2. Mechanical thrombectomy: for large‑vessel occlusion within 24 hours if salvageable tissue
  3. Antiplatelet therapy: Aspirin 325 mg within 48 hours (if not receiving tPA)
  4. BP management: permissive hypertension (up to 220/120) unless receiving tPA
  5. Secondary prevention: statin, antiplatelet, carotid endarterectomy if >70% stenosis

Complications & Prognosis

  • Hemorrhagic transformation
  • Cerebral edema and herniation
  • Aspiration pneumonia
  • Post‑stroke depression and cognitive impairment

ICU Criteria

ICU admission if: large MCA infarction with edema, need for thrombectomy, or post‑tPA monitoring.

Clinical Vignette

A 72‑year‑old woman with atrial fibrillation (not on anticoagulation) develops sudden right‑sided weakness and aphasia while watching TV. NIHSS is 18. CT shows no hemorrhage; CTA reveals left MCA occlusion.

Pearls & Pitfalls

  • Do not delay tPA to control BP – use IV labetalol or nicardipine to lower BP to <185/110 before thrombolysis.
  • Posterior circulation strokes may present with isolated vertigo – the HINTS exam can differentiate from peripheral causes.

Discharge & Follow-Up

Start anticoagulation for atrial fibrillation (typically within 2‑14 days, depending on infarct size). Speech therapy, physical therapy, occupational therapy. Modify cardiovascular risk factors.

Literature & Guidelines

AHA/ASA 2024 Guidelines for the Early Management of Acute Ischemic Stroke. PMID: 38516530.

Personal Clinical Notes