What Is Cystic Adventitial Disease of the Popliteal Artery?
Adventitial cystic disease is a rare condition in which a cyst forms in a blood vessel, obstructing blood flow to the muscles. The popliteal artery in the lower leg is usually affected. The most common symptoms are pain or cramping in the lower leg, especially during exercise. Adventitial cystic disease is extremely uncommon, accounting for only 0.1 % of all vascular diseases. In 1947, Atkins and Key described the adventitial cystic disease, which affected the right external iliac artery. Since then, over 300 cases have been reported. The adventitial cystic disease primarily affects the popliteal artery unilaterally (85 % of the time) and typically manifests as intermittent claudication, though bilateral involvement has been reported, as have the external iliac, common femoral, radial, and ulnar arteries.
What Is the Prevalence?
The adventitial cystic disease affects over 80 % of men between the ages of 40 and 50 (range: 11 to 70), and its prevalence is 1:200 cases of calf claudication. A clinical diagnosis is frequently challenging because the young also have a low risk for vascular disease. Angiograms show scimitar or hourglass signs when the cysts compress the arterial lumen eccentrically or concentrically. The affected popliteal artery significantly impacts the severity of ischemic symptoms. Adventitial cystic disease can cause symptoms that worsen with exercise. The obstruction of functional flow during dynamic exercise is thought to result from adventitial cystic disease. Surgery is necessary to treat the symptoms because the patient's right foot's pulse is normal at rest but decreases after exercise.
What Are the Causes of Cystic Adventitial Disease?
Trauma, ganglions, systemic disorders, and embryonic development have all been put forth as possible causes of adventitial cystic disease. According to the trauma theory, cystic change is ultimately brought on by repeated trauma that results in arterial adventitia degeneration. According to the ganglion theory, synovial cysts develop close to joints, travel along vascular branches, and then settle in the adventitia of significant vessels. According to the theory of systemic disorders, adventitial cystic disease is a type of generalized connective tissue disorder. According to developmental theory, mesenchymal cells from nearby mucin-rich joints mistakenly relocate to the adventitia during embryogenesis. The pathogenesis of every clinical case, however, cannot be explained by a single theory. A unifying hypothesis was put forth by Levien et al. based on the embryology of the affected site and the susceptible blood vessels. They assert that during embryological development, a joint-related ganglion-like structure is integrated into a target vessel and that this synovial rest, or ganglion, secretes and grows over time to form within the adventitial wall later in life, suggesting that both the developmental and ganglion theories are relevant.
What Are the Signs and Symptoms?
Clinically, a patient with CAD typically exhibits new-onset intermittent limb claudication unrelated to tobacco use or diabetes. The symptoms may appear suddenly or more gradually. Physical examination may or may not reveal the distal limb pulses to be absent at rest. In CAD, Ishikawa's sign - the loss of the foot pulses with knee flexion can be observed. This distinguishes CAD from popliteal entrapment syndrome, in which the gastrocnemius would contract during active plantar flexion or passive dorsiflexion of the foot, and the pulse would vanish. In CAD, claudication symptoms may be temporary and resolve on their own.
How Is Cystic Adventitial Disease Treated?
Different approaches are taken to treat adventitial cystic disease based on the state of affected vessels. These include surgery, percutaneous aspiration, and percutaneous endovascular intervention. First, conservative management of CAD should be given priority because the cysts in CAD may resolve naturally, or the patient may not feel uncomfortable enough to require more invasive treatment options. The preferred method of treatment was surgery. Various authors have suggested various methods in the past, including complete resection with bypass, excision of the cyst, surgical aspiration of the cyst, or "ex-arterectomy," which involves circumferential resection of the diseased adventitia.
Cyst aspiration is a significantly less invasive procedure, but it has a high recurrence rate. It may be successful to remove the cyst's contents (evacuation) while keeping the involved artery intact, and it may be successful in resecting the affected portion of the vessel and inserting a vein graft or prosthesis. Unsatisfactory results have been obtained from endovascular interventional therapy.
What Is the Diagnosis?
Grayscale Doppler ultrasonography (U.S.) is a less invasive, suitable diagnostic technique as standard treatment. In contrast, CT and MRI are better suited for assessing cyst morphology and potential communication between a cyst and an adjacent joint. The MRI results for the adventitial cystic disease are evident because cysts typically appear as homogeneous, low signal intensity regions on T1-weighted images and as multi-loculated high signal intensity regions next to vessels on T2-weighted images. The best preoperative planning involves three-dimensional CT reconstructions with volume rendering or MRA. Due to its invasive nature, traditional digital subtraction angiography (DSA) is rarely used. Popliteal artery entrapment syndrome (PAES) is one of the potential diagnoses, and multi-planar data acquisition can help distinguish this condition from adventitial cystic disease by determining the morphological extent of arterial intramural cystic lesions.
The diagnosis of CAD has traditionally been made using angiography. On angiogram, the affected vessels can have a variety of appearances, including eccentric lumen narrowing (scimitar sign), hourglass lumen narrowing, or complete occlusion. A helpful indicator of CAD is the absence of post-stenotic dilatation. However, a nonspecific complete luminal obstruction that is detected during angiography in some cases may be mistaken for an endoluminal lesion.
Conclusion:
Adventitial cystic disease of the popliteal artery is a rare but significant cause of peripheral vascular insufficiency in young people with no specific risk factors of atherosclerosis. Due to the possibility of recurrence or graft occlusion, long-term follow-up is essential. In light of this, adventitial cystic disease should be considered in relatively young people who complain of intermittent claudication.
