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.