Cerebrovascular Diseases

Ischemic Stroke - Brain Attack Basics

• Pathophysiology:
  • Core Infarct: Irreversible neuronal death due to severe ischemia.
  • Ischemic Penumbra: Potentially salvageable tissue surrounding core; target for reperfusion.
  • Cytotoxic Edema: Intracellular swelling due to Na+/K+ pump failure; early sign.
• CT (NECT - Non-Enhanced CT):
  • Early Signs (often subtle, within 6 hrs):
    • Hyperdense MCA sign (clot in MCA).
    • Loss of insular ribbon.
    • Sulcal effacement.
    • Obscuration of lentiform nucleus.
  • ASPECTS (Alberta Stroke Program Early CT Score): 0-10 scale (10 regions: M1-M6, Insula, Caudate, Lentiform, Internal Capsule). 📌 Score < 6 indicates poor outcome.
• MRI:
  • DWI/ADC Mismatch:
    • DWI: Bright (restricted diffusion) within minutes.
    • ADC: Dark (confirms true restriction).
  • FLAIR: Detects subacute infarcts (hyperintense after ~6 hrs).
  • PWI (Perfusion-Weighted Imaging): Identifies penumbra (mismatch between PWI and DWI).
• Vascular Imaging:
  • CTA/MRA: Detects large vessel occlusion (LVO).

⭐ Diffusion-Weighted Imaging (DWI) is the most sensitive sequence for detecting acute ischemic stroke within minutes of onset.

Hemorrhagic Stroke - When Vessels Burst

• Intracerebral Hemorrhage (ICH): Bleeding within brain parenchyma.
  • Causes: Hypertension (commonest), amyloid angiopathy (lobar, elderly), AVM, tumor.
  • Locations: Basal ganglia, thalamus, pons, cerebellum.
• Subarachnoid Hemorrhage (SAH): Bleeding into subarachnoid space.
  • Causes: Ruptured berry aneurysm (~85%), AVM, trauma.
    • 📌 Aneurysm sites (Circle of Willis): ACOM > PCOM > MCA.
  • Symptom: "Thunderclap headache".
• Imaging:
  • NECT: Primary for acute blood (hyperdense).

    ⭐ Non-contrast CT (NECT) is the initial imaging modality of choice for suspected acute stroke to rapidly differentiate ischemic from hemorrhagic stroke.

  • CTA: Identifies aneurysms, vascular lesions.
  • MRI (FLAIR, GRE/SWI): Subacute blood, hemosiderin.
• Grading (SAH):
  • Hunt & Hess: Clinical severity (Grades 1-5).
  • Fisher Scale: CT appearance, vasospasm risk (Grades 1-4).

Vascular Malformations - Brain's Tangled Plumbing

• Arteriovenous Malformation (AVM)
  • Nidus, direct artery-to-vein shunting.
  • Feeding arteries, early draining veins.
  • Angio: 'bag of worms'. High hemorrhage risk.
• Cavernous Malformation (Cavernoma)
  • MRI: 'popcorn'/'berry' (T2WI).
  • Hemosiderin rim (dark T2/GRE/SWI). No AV shunting.
• Developmental Venous Anomaly (DVA)
  • 'Caput medusae'/'palm tree': trans-cortical draining vein.
  • Usually incidental, benign.
• Capillary Telangiectasia
  • Often pontine; 'brush-like' enhancement.
  • Usually incidental, benign.

⭐ Developmental Venous Anomalies (DVAs) are the most common cerebral vascular malformation and are typically benign 'leave-me-alone' lesions, often associated with cavernomas.

Beyond Strokes - Veins, Smoke, Fire

• Cerebral Venous Thrombosis (CVT)
  • Thrombus in dural sinuses/cortical veins.
  • NECT: 'dense clot sign'/'cord sign'.
  • CECT: 'empty delta sign'.
  • MRI/MRV: Loss of flow void, thrombus signal, venous infarcts (often hemorrhagic, non-arterial territories).

  ⭐ The 'empty delta sign' on contrast-enhanced CT or MR venography is a characteristic finding of dural venous sinus thrombosis, particularly of the superior sagittal sinus.

• Moya Moya Disease
  • Progressive stenosis/occlusion of terminal ICA & proximal ACA/MCA.
  • Angiography: 'puff of smoke' collaterals. 📌 "Moya Moya" = "puff of smoke" in Japanese.
  • 
• CNS Vasculitis
  • Inflammatory; segmental narrowing/beading of vessels.
  • Multifocal infarcts of varying ages on MRI.

High‑Yield Points - ⚡ Biggest Takeaways

• MCA territory infarcts are most common; hyperdense MCA sign on NCCT is an early sign.
• MRI (DWI) is most sensitive for acute ischemic stroke, detecting it within minutes.
• Lacunar infarcts (<1.5 cm) are deep, often linked to hypertension or diabetes.
• Watershed infarcts affect arterial border zones due to systemic hypoperfusion.
• For SAH, CT is initial; LP if CT negative. Ruptured berry aneurysms are a key cause.
• Cerebral Amyloid Angiopathy (CAA) causes recurrent lobar hemorrhages in the elderly_._