Vascular Sonography 2: Extracerebral Arterial Exam Study Guide

1. Extracerebral Arterial Exam Overview

  • Definition of "Extracerebral": Examination of arteries outside of the head, specifically neck vessels.

  • Case Study Introduction:

    • Patient Profile: A 68-year-old male presenting for an assessment of carotid arteries.

    • Clinical Indication: Requisition states "? TIA’s."

    • Transient Ischemic Attack (TIA): A "mini stroke" where symptoms resolve within 2424 hours.

    • Signs to Assess: Slurred/wrong speech, weakness/drooping, and bilateral blood pressure (BP).

2. Risk Factors for Vascular Disease

  • Hypertension: Injures the vessel wall.

  • Diabetes: Vascular atherosclerosis at an early age; leads to "hard vessels."

  • Smoking: Causes persistent irritation of the endothelial lining.

  • Obesity and Diet: High-fat and high-cholesterol diets.

  • Dyslipidemia: Abnormal plasma lipid levels initiate plaque formation.

  • Hypercholesterolemia: Genetic defect in LDL receptors.

  • Sex: Male predominance below age 50; risk equalizes after age 50 due to estrogen.

  • Age: Risk increases with cumulative plaque buildup.

  • Patent Foramen Ovale (PFO): Clots can travel to the brain.

  • Physical Inactivity.

  • Genetic Predisposition/Family History: Increases risk for stroke, cardiac disease, or diabetes.

  • Homocystinaemia: Elevated homocysteine levels lead to increased stroke risk.

  • Cardiac Disease.

  • Previous TIA or Stroke.

  • Screening: Performed before major cardiac procedures.

3. Physical Examination and Indirect Assessment

  • Auscultation for Bruits:

    • Turbulent blood flow creating a bruit.

    • May not be detected in severe stenosis.

    • A "thrill" is a palpable bruit.

  • Bilateral Blood Pressures:

    • A difference of > 20 \, mmHg indicates a possible subclavian steal.

4. Signs and Symptoms of Cerebrovascular Compromise

4.1 Anterior Circulation (Hemispheric/Lateralizing)

  • Supplied by Internal Carotid Arteries (ICAs).

  • Contralateral Rule: Left ICA disease causes right body symptoms.

  • Visual Exception: Visual symptoms are typically unilateral and ipsilateral.

  • Specific Conditions:

    • Amaurosis Fugax: "Black curtain" over one eye.

    • Aphasia/Dysphasia: Language comprehension or production issues.

    • Dysphagia: Difficulty swallowing.

    • Dysarthria: Impaired speech articulation.

    • Hemiparesis/Hemiplegia: Weakness or paralysis on one side.

    • Homonymous Hemianopsia: Visual field loss in half of vision.

    • Paresthesia: Tingling or numbness.

4.2 Posterior Circulation (Vertebrobasilar/Non-lateralizing)

  • Supplied by vertebral arteries to cerebellum and posterior hemispheres.

  • Specific Conditions:

    • Ataxia: Lack of coordination.

    • Binocular Blindness: Loss of vision in both eyes.

    • Diplopia: Double vision.

    • Dizziness.

    • Drop Attacks: Sudden falls while walking.

    • Syncope: Transient loss of consciousness.

    • Vertigo: Sensation of spinning.

4.3 Miscellaneous/Visual Notes

  • Headache, Neck Pain, Confusion: General neurological symptoms.

  • Visual Distribution: Unilateral disturbances are typically ipsilateral and anterior; bilateral disturbances can be anterior or posterior.

5. Questions & Discussion: Case Study Follow-Up

  • Patient Status: Normal BP, non-smoker, no family history, vision problems for a month.

  • Follow-Up Questions: Ask about one or both eyes, precise sensation description.

  • Scenarios: If loss of vision in the left eye, focus on left ICA (Amaurosis Fugax). If diplopia, focus on posterior circulation.

6. Classification of Neurologic Deficits

  • Asymptomatic: Bruit found without symptoms.

  • Transient Ischemic Attack (TIA): Neurologic deficit lasting < 2424 hours.

  • Resolving Ischemic Neurologic Deficit (RIND): Lasts > 2424 hours but resolves within 33 weeks with no permanent damage.

  • Cerebrovascular Accident (CVA/Stroke): Causes permanent brain damage.

  • Vertebrobasilar Insufficiency (VBI): Causes posterior circulation symptoms.

7. Mechanisms of Disease

  • Cardiac Causes: Emboli from atrial fibrillation or perfusion cessation.

  • Carotid Origin: Atherosclerotic stenosis leading to thrombosis or emboli.

  • Cerebral Artery Rupture: Aneurysm or vasospasm.

  • Miscellaneous: Sickle cell anemia or congenital AVM.

8. Plaque Formation and Morphology

  • Arteriosclerosis: General hardening of arteries, loss of elasticity.

  • Atherosclerosis: Arterial disease involving hard and soft plaque.

8.1 Pathogenesis Stages

  • Stage 1: Injury to endothelial lining.

  • Stage 2: Lipids enter, inflammation, fatty streak forms.

  • Stage 3: Platelet deposition and scar tissue formation.

  • Stage 4: Hemorrhage causes ischemia, unstable plaque can release emboli.

9. Ultrasound Characterization of Plaque

9.1 Surface Characteristics

  • Smooth: Continuous surface.

  • Irregular: Discontinuous; increased embolization risk.

  • Ulceration: Hard to confirm, often reported as irregular.

9.2 Echogenicity

  • Anechoic: Indicates soft, dangerous plaque.

  • Hypoechoic: Fibrofatty plaque.

  • Hyperechoic: Fibrous tissue.

  • Calcified: Presence of calcium often non-obstructive if flow is normal.

9.3 Echotexture

  • Homogenous: Consistent echogenicity.

  • Heterogeneous: Contains various elements.

10. Quantitative Stenosis Measurement

10.1 NASCET

  • Normal: ICA PSV <125\,cm/s.

  • 50–69% Stenosis: ICA PSV 125−230 cm/s125 - 230\,cm/s.

  • >70% Stenosis: Variable; visible plaque; non-detectable flow in occlusion.

10.2 Formulas

  • Diameter Reduction (NASCET): [1−(d/D)]imes100[1 - (d / D)] imes 100

  • Area Reduction: [(A−a)/A]imes100[(A - a) / A] imes 100

11. Doppler Principles in Carotid Assessment

  • Color Doppler: Locates stenosis.

  • Spectral Doppler: Most accurate for stenosis extent.

  • PSV: Highest velocity; key parameter.

  • EDV: Remains normal if stenosis is mild.

12. Treatments for Carotid Artery Disease

  • Medical: Risk factors modification; TPA within 33 hours of ischemic stroke; anticoagulants.

  • Surgical:

    • Carotid Endarterectomy: Plaque removal.

    • Angioplasty and Stenting: Opening of stenosis with a mesh tube.

13. Post-Intervention Duplex Evaluation

  • Endarterectomy Follow-up: First exam within 3030 days.

  • Stent Complications: Deployment issues, neointimal hyperplasia, progressive atherosclerosis.

14. Other Carotid Pathologies

  • Carotid Artery Dissection: Tear causing a false lumen; stroke/TIA risk.

  • Fibromuscular Dysplasia (FMD): Non-atherosclerotic disease affecting mainly women.

  • Carotid Body Tumor (CBT): Highly vascular, benign tumor.

  • Aneurysms and Pseudoaneurysms: True ballooning vs. walled-off blood leak.

  • Arteritis (Vasculitis): Inflammation affecting arteries.

15. Other Imaging Modalities

  • Cerebral Arteriography (Angiography): Invasive, high risk.

  • Computed Tomography (CT): Spiral imaging.

  • MRA/MRI: Detailed, lower risk imaging.

16. Questions & Discussion: General Notes

  • Tardus Parvus Diagnosis: Check proximally for stenosis source.

  • Innominate Artery: Stenosis here affects flow.

  • High/Low Velocities Bilaterally: Consider cardiac output as a cause.