Epidemiology

Etiology

• Atherosclerosis
• Takayasu arteritis
• Thoracic surgery

Pathophysiology

• Stenosis of the subclavian artery proximal to the origin of the vertebral artery (Left subclavian artery ∼ 70% of cases) → hypoperfusion distal to the stenosis → reversal of blood flow in ipsilateral vertebral artery → compensation through collateral arteries → reduced blood flow in the basilar artery → reduced cerebral perfusion upon exertion involving the affected arm
  • During arm exertion, increased metabolic demand causes vasodilation and blood diversion from the vertebral artery to supply the arm

Clinical features

• Most patients are asymptomatic
• Limb ischemia (on exertion)
  • Pain, paresthesia
  • Pale, cool skin
  • Weak, delayed radial pulse
  • Disparity in BP > 15 mm Hg
• Neurologic symptoms (due to vertebrobasilar insufficiency)
  • Dizziness, vertigo
  • Ocular findings (e.g., diplopia)
  • Syncope

Diagnostics

Imaging of the cerebral and upper extremity arteries, e.g., via Doppler ultrasound, duplex ultrasound, or magnetic resonance angiography, shows reversal of blood flow and/or atherosclerosis.

Treatment