Cerebrovascular Diseases

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Stroke Fundamentals - Brain Attack Basics

  • Definition: Sudden focal neurological deficit of vascular origin. "Brain Attack" = medical emergency. Time is Brain!
  • Types:
    • Ischemic (~87%): Due to ↓ blood flow.
      • Thrombotic: Local clot (e.g., MCA atherosclerosis).
      • Embolic: Distant clot (e.g., AF, carotid plaque).
      • Systemic Hypoperfusion: Affects watershed zones.
    • Hemorrhagic (~13%): Due to vessel rupture.
      • Intracerebral (ICH): Bleeding into parenchyma.
      • Subarachnoid (SAH): Bleeding into subarachnoid space.
  • Risk Factors:
    • Non-Modifiable: Age (>55), Male sex, Ethnicity, Family Hx.
    • Modifiable:
      • Hypertension (HTN): #1 factor.
      • Diabetes Mellitus (DM).
      • Hyperlipidemia.
      • Smoking.
      • Atrial Fibrillation (AF).
      • Carotid Stenosis.
      • Obesity. Axial CT: Normal brain vs hyperacute ischemic stroke

⭐ Hypertension is the single most important modifiable risk factor for all stroke types.

Ischemic Stroke - Clots & Consequences

  • Pathogenesis: ~85% of strokes; neuronal death from ↓ blood flow. Major types:

    • Thrombotic: Atherosclerotic plaque rupture in cerebral artery (e.g., MCA, basilar). Common sites: carotid bifurcation, MCA origin, basilar artery.
    • Embolic: Detached clot from distant site (e.g., heart in AFib, valvular disease; carotid atheroma) lodges in cerebral artery.
  • Risk Factors: HTN, DM, hyperlipidemia, smoking, AFib.

  • Core Pathophysiology: Occlusion → Ischemia (core: irreversible damage; penumbra: salvageable tissue) → Infarction.

    • Mechanisms: Excitotoxicity (glutamate), inflammation, free radicals, apoptosis.
  • Timeline of Pathological Changes:

  • Gross brain section with old cystic infarct

⭐ Liquefactive necrosis is characteristic of CNS infarcts due to high lipid content and lack of significant supporting stroma, leading to a fluid-filled cystic cavity.

  • Complications: Cerebral edema (can cause herniation), hemorrhagic transformation (especially in embolic strokes), seizures.
  • 📌 MCA Territory: Most common site. Contralateral hemiparesis/sensory loss (face/arm > leg), aphasia (dominant hemisphere), hemineglect (non-dominant).

Hemorrhagic Stroke & Aneurysms - Bleeds & Blowouts

  • Intracerebral Hemorrhage (ICH): Bleeding into brain parenchyma.
    • Etiology: Hypertension (Charcot-Bouchard), CAA (elderly, lobar), AVMs, tumors, coagulopathy.
    • Clinical: Abrupt focal deficits, headache, vomiting, ↓consciousness.
  • Subarachnoid Hemorrhage (SAH): Bleeding into subarachnoid space.
    • Etiology: Ruptured saccular (berry) aneurysm (~85%), AVM, trauma.
    • Clinical: Sudden "worst headache of my life" (thunderclap), nuchal rigidity, photophobia, LOC.
    • Dx: Non-contrast CT. If negative, LP for xanthochromia (after 6-12 hrs).
    • Complications: Rebleeding (peak 24-48 hrs), vasospasm (days 3-14, nimodipine prophylaxis), hydrocephalus, seizures.
  • Aneurysms: Localized arterial dilations.
    • Saccular (Berry): Most common. Arterial bifurcations (Circle of Willis: AComA, PComA, MCA). Assoc: ADPKD, Ehlers-Danlos. Risks: Smoking, HTN. Berry Aneurysm Locations on Circle of Willis
    • Charcot-Bouchard: Small penetrating arteries (lenticulostriate). Due to chronic HTN. Rupture causes ICH.
    • Mycotic: Infected emboli (e.g., endocarditis).

⭐ Nimodipine prevents SAH-associated vasospasm; not for initial bleed treatment.

High‑Yield Points - ⚡ Biggest Takeaways

  • MCA (Middle Cerebral Artery) is the most frequent site for embolic strokes.
  • Hypertensive hemorrhage often involves Charcot-Bouchard microaneurysms in the basal ganglia or pons.
  • Lacunar infarcts are small, deep strokes linked to hypertension and diabetes mellitus.
  • Watershed infarcts occur in arterial border zones due to systemic hypoperfusion.
  • Berry aneurysms are the leading cause of non-traumatic Subarachnoid Hemorrhage (SAH), typically at ACA-ACoA junction.
  • The ischemic penumbra represents at-risk, salvageable brain tissue surrounding an infarct core.
  • Hemorrhagic transformation is a significant complication following reperfusion therapy for ischemic strokes.

Practice Questions: Cerebrovascular Diseases

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What is the most common cause of subarachnoid hemorrhage?

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Flashcards: Cerebrovascular Diseases

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_____ hemorrhage most commonly occurs due to rupture of Charcot-Bouchard microaneurysms, secondary to chronic hypertension

TAP TO REVEAL ANSWER

_____ hemorrhage most commonly occurs due to rupture of Charcot-Bouchard microaneurysms, secondary to chronic hypertension

Intraparenchymal

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