Subclavian Steal Syndrome Does NOT Typically Cause Arm Swelling
Subclavian steal syndrome characteristically presents with neurological symptoms (vertebrobasilar insufficiency) and arm claudication, but arm swelling is not a recognized feature of this condition. 1
Typical Clinical Presentation
The actual symptoms of subclavian steal syndrome include:
Neurological Manifestations
- Vertebrobasilar insufficiency symptoms are the hallmark: dizziness, vertigo, blurred vision, syncope, ataxia, diplopia, dysphasia, dysarthria, confusion, drop attacks, and motor deficits—typically worsened by arm exercise 1, 2
- Visual disturbances and facial sensory deficits during arm movements may occur 1, 2
Upper Extremity Manifestations
- Arm claudication (crampy, exercise-induced muscular fatigue and pain) is the primary upper extremity symptom 1, 2
- In severe cases with more distal disease: rest pain, digital ischemia with gangrene or necrosis, coldness, and pallor 1, 2
- Paresthesias and pulse deficits may be present 1
Special Presentations
- Coronary-subclavian steal: angina during arm exercise in patients with internal mammary artery bypass grafts 1, 2
- Hemodialysis access dysfunction in patients with arteriovenous fistulas 1, 2
Why Swelling Is NOT a Feature
The pathophysiology of subclavian steal syndrome involves arterial insufficiency and flow reversal, not venous obstruction or lymphatic compromise, which are the mechanisms that cause limb swelling 3, 4. The syndrome results from proximal subclavian artery stenosis or occlusion causing retrograde blood flow in the ipsilateral vertebral artery, leading to reduced arterial perfusion—not fluid accumulation 1, 2, 3, 4.
Key Diagnostic Findings
- Blood pressure asymmetry between arms (≥15 mmHg difference) is highly suspicious for subclavian stenosis 1, 2
- Periclavicular or infraclavicular bruit suggests subclavian stenosis 1, 2
- Duplex ultrasonography demonstrates flow reversal in the vertebral artery with high-velocity intrastenotic flows (PSV ≥230 cm/s for 50% stenosis) 1, 2
- Most patients (>90%) with at least 50% proximal subclavian stenosis have vertebral artery flow reversal, though many remain asymptomatic 1, 2, 3
Clinical Pitfall
If a patient presents with arm swelling and suspected vascular disease, consider alternative diagnoses such as venous thrombosis, lymphedema, or superior vena cava syndrome rather than subclavian steal syndrome 1. The presence of swelling should prompt investigation for venous or lymphatic pathology, not arterial steal phenomenon.