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  • • Symptoms more often result from emboli than hypoperfusion

    • 80% of patients with occlusive cerebrovascular disease have accessible arterial lesion in neck/chest

    • When blood supply decreases below critical level, cellular death occurs in minutes

    • Embolization most common mechanism of stroke from carotid lesions

    • Most strokes due to lesions of internal carotid but can be from innominate/ aorta

    • Low wall shear stress, flow separation, loss of unidirectional flow may lead to atherosclerosis in carotid bulb

    • Neurologic dysfunction without infarction can be produced in 2 ways:

    • 1. Cerebral embolization by microembolic fragments

      2. Transient reduction in cerebral perfusion

    • Antiplatelet therapy decreases stroke rates by 5%

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Epidemiology

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  • • 33% of patients who have had transient ischemic attacks (TIAs) eventually suffer stroke

    • 20% of patients with amaurosis fugax will suffer stroke

    • Stroke risk after TIA correlates with severity of internal carotid stenosis

    • Mortality from initial stroke is 20-30%

    • Subclavian stenosis more common in left artery than in right

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Symptoms

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  • Asymptomatic disease

    • -Bruit may be heard

    TIA

    • -Short-lived paresis or numbness of contralateral arm or leg that lasts < 24 h

      -Symptoms depend on location and size of embolus, which determines rate of dissolution

    Amaurosis fugax

    • -Microembolus to ophthalmic artery produces temporary mononuclear vision loss (lamp shade), Hollenhorst plaques (emboli visible in retina)

    Acute unstable neurologic defect

    • -Patients may have crescendo TIA, stroke in evolution, waxing and waning deficits

      -Treat urgently or may progress to stroke

    Completed stroke

    • -50% will suffer another stroke

    Vertebrobasilar disease

    • -Emboli or hypoperfusion of posterior system causes drop attacks, clumsiness, vertigo, diplopia, dysphagia, dysequilibrium

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Signs

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  • Palpation

    • -Only the pulse of common carotid can be felt directly

      -Thus, internal carotid may be occluded even when neck pulse is normal

    Bruits

    • -High in lateral neck indicates common carotid bifurcation stenosis

      -Of lower trapezius indicates vertebral stenosis

      -Along full length of right common carotid and subclavian indicates innominate stenosis

    Brachial blood pressure discrepancy

    • -Indicates arterial stenosis (greater in left subclavian artery than in right)

    Subclavian steal syndrome

    • -Neurologic symptoms upon exercise of upper extremity due to reversal of vertebral artery flow (collateral to arm)

      -Arm effort fatigue with proximal stenosis

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Imaging Findings

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  • Carotid duplex US: Screening for stenosis

    Cerebral arteriography: Provide extracranial and intracranial anatomy of carotid and vertebral arteries

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  • • Carotid duplex US useful to demonstrate plaque morphology and degree of stenosis rapidly and accurately

    • Carotid duplex US velocity criteria indicates degree of luminal narrowing—increases with increased stenosis

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  • • Duplex US is initial test

    • Arteriogram should be only done selectively

    NASCET trial: Reported in 2 major parts

    • -Symptomatic patients with 70-99% stenosis randomized to receive aspirin alone or aspirin plus carotid endarterectomy

      -2-year stroke rate was 26% for aspirin alone vs 9% for aspirin plus carotid endarterectomy

      -In patients ...

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