Symptoms of Popliteal Artery Aneurysm
Popliteal artery aneurysms are often asymptomatic until they develop complications such as thrombosis, embolization, or compression of adjacent structures, which can lead to limb-threatening ischemia and potential amputation.
Common Presenting Symptoms
Asymptomatic Presentation
- Many popliteal artery aneurysms (PAAs) are initially asymptomatic and discovered incidentally
- Palpable pulsatile mass in the popliteal fossa is the most common physical finding 1
- Up to 50% are bilateral, and approximately 50% are associated with aneurysms in other locations, particularly the abdominal aorta 1
Symptomatic Presentation
Acute limb ischemia (most common symptomatic presentation)
- Rest pain
- Sudden onset of coldness, numbness, or pain in the leg or foot
- Diminished or absent distal pulses
- Mottling or cyanosis of the foot
- Sensory and motor deficits in severe cases
Chronic limb ischemia
- Intermittent claudication
- Rest pain
- Tissue loss or gangrene in advanced cases
Local compression symptoms
- Popliteal vein compression causing leg swelling and deep vein thrombosis
- Tibial nerve compression causing paresthesia or pain
- Discomfort behind the knee, especially with flexion
Rare symptoms
- Rupture (occurs in less than 5% of cases) presenting with severe pain and swelling 1
- Pulsatile mass with associated bruit
Complications and Natural History
- Thrombosis occurs in approximately 39% of popliteal aneurysms, more frequently in larger aneurysms 1
- According to data from the American Heart Association, up to 50% of previously asymptomatic popliteal aneurysms become symptomatic within 2 years of discovery and 75% within 5 years 1
- Symptomatic popliteal aneurysms typically:
- Exceed 2.0 cm in diameter
- Contain substantial mural thrombus on ultrasound imaging
- Are associated with distal tibioperoneal arterial occlusions from previous emboli 1
Risk Factors for Symptom Development
- Aneurysm size greater than 2.0 cm (higher complication rate of 14% vs. 3.1% for smaller aneurysms) 1
- Presence of mural thrombus
- Limited or poor distal runoff
- History of other arterial aneurysms
Diagnostic Approach
When a popliteal mass is suspected:
- Ultrasound examination is the first-line diagnostic tool (Class I recommendation) 1, 2
- Further imaging with CT or MRI may be necessary to evaluate extent and relationship to surrounding structures
- Arteriography may be needed to assess distal runoff vessels, especially in cases of acute ischemia 1
Clinical Pearls and Pitfalls
- Important pitfall: Thrombosis of popliteal arterial aneurysms accounts for approximately 10% of acute arterial occlusions in elderly men and is commonly mistaken for an embolic event 1
- Key clinical clue: In cases of acute limb ischemia, the presence of a prominent popliteal pulse in the opposite leg suggests bilateral popliteal aneurysms 1
- Critical warning sign: Even after surgical repair of symptomatic popliteal aneurysms, 56% of patients may continue to experience distal ischemia, and 19% may eventually require amputation due to prior emboli with thrombosis of downstream vessels 1
- Surveillance recommendation: Asymptomatic popliteal aneurysms smaller than 2.0 cm should be monitored with annual ultrasound imaging 1
Management Implications
- Patients with popliteal aneurysms ≥2.0 cm in diameter should undergo repair to reduce the risk of thromboembolic complications and limb loss (Class I recommendation) 1
- In patients with acute ischemia and absent runoff, catheter-directed thrombolysis or mechanical thrombectomy is suggested to restore distal runoff and resolve emboli 1, 2
- Early intervention is crucial as outcomes are significantly better when surgery is performed on asymptomatic aneurysms compared to symptomatic ones 3
Remember that popliteal artery aneurysms have a high risk of complications when left untreated, with potentially devastating consequences including limb loss. Recognizing the symptoms early and appropriate intervention are essential for preserving limb function and preventing morbidity.