What are the signs and symptoms of arterial limb occlusion?

Signs of Arterial Limb Occlusion

The hallmark signs of acute arterial limb occlusion are the classic "6 Ps": Pain, Pallor, Pulselessness, Poikilothermia (cold extremity), Paresthesias, and Paralysis. 1, 2

Clinical Presentation by Severity

The presentation depends critically on whether the occlusion is acute (sudden) versus chronic, and the degree of collateral circulation present:

Acute Limb Ischemia (ALI) - Classic Presentation

Acute occlusion (<2 weeks duration) presents with sudden onset of:

• Pain - Abrupt onset of severe limb pain, typically the first and most prominent symptom 1, 3, 4
• Pallor - Pale appearance of the affected limb, especially when elevated 1, 2
• Pulselessness - Absent distal pulses on palpation 1, 2
• Poikilothermia - Cold extremity compared to the contralateral limb 1, 2
• Paresthesias - Numbness and abnormal sensations, indicating nerve ischemia 1, 4
• Paralysis - Muscle weakness or complete inability to move the limb, a late and ominous sign 1, 2

Severity Classification and Associated Signs

The Rutherford classification stratifies ALI into three critical categories based on physical findings: 1

Category I - Viable Limb:

• No immediate threat to limb viability 1
• No sensory loss 1
• No muscle weakness 1
• Audible arterial Doppler signals 1
• Audible venous Doppler signals 1

Category II - Threatened Limb (Salvageable if promptly treated):

• IIa (Marginally threatened): Minimal sensory loss (toes only) or none; no muscle weakness; often inaudible arterial Doppler but audible venous Doppler 1
• IIb (Immediately threatened): Sensory loss extending beyond toes with rest pain; mild to moderate muscle weakness; usually inaudible arterial Doppler; audible venous Doppler 1

Category III - Irreversible:

• Major tissue loss or permanent nerve damage inevitable 1
• Profound sensory loss (anesthetic limb) 1
• Profound paralysis with muscle rigor 1
• Inaudible arterial AND venous Doppler signals 1

Distinguishing Features by Etiology

Embolic Occlusion

Emboli cause more severe, sudden presentations because they occlude previously normal vessels without established collaterals: 1

• Sudden onset or sudden worsening of symptoms (often within minutes to hours) 1
• Known embolic source present: atrial fibrillation, recent myocardial infarction, left ventricular aneurysm, dilated cardiomyopathy, or proximal arterial aneurysm 1
• Absence of antecedent claudication or prior symptoms of peripheral artery disease 1
• Normal pulses and Doppler pressures in the contralateral limb 1
• More likely to cause limb-threatening ischemia compared to thrombosis 1

Thrombotic Occlusion

Thrombosis on pre-existing atherosclerotic disease typically presents less severely due to established collaterals: 1

• History of claudication or known peripheral artery disease 1
• More gradual onset (hours to days) 1
• May have diminished pulses in contralateral limb 1

Chronic Critical Limb Ischemia (CLI) - Distinct Presentation

CLI is fundamentally different from ALI, characterized by chronic symptoms (≥2 weeks duration): 1, 5

• Ischemic rest pain - Worse when supine, improves with limb dependency 5
• Non-healing ulcers or wounds - Typically on toes, heel, or pressure points 1, 5
• Gangrene - Focal or diffuse tissue necrosis 1, 5
• Dependent rubor - Redness when limb hangs down 5, 2
• Elevation pallor - Limb becomes pale when elevated 2
• Trophic skin changes - Thin, shiny skin; hair loss; thickened nails 5
• Diminished or absent pulses 5

Critical Pitfalls to Avoid

Arterial embolism can occasionally occur WITHOUT symptoms, while thrombosis can produce sudden severe ischemia - do not rely solely on presentation tempo to distinguish etiology. 1

Diabetic patients with neuropathy may present with severe CLI and tissue loss but minimal or no pain - always suspect CLI in diabetics with known peripheral artery disease regardless of pain complaints. 5

Bilateral lower limb ischemia with paraplegia suggests "saddle embolus" at the aortic bifurcation - this carries high mortality and requires emergent intervention. 1

Painless acute paraparesis can be the presenting symptom of bilateral femoral artery occlusion - neurological deficits may dominate the clinical picture. 6