Cerebrovascular Disease, Atherosclerotic

• • 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%

Epidemiology

• • 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

Symptoms

• • 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

Signs

• • 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

Imaging Findings

• • Carotid duplex US: Screening for stenosis

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

• • 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

• • 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% ...