Spontaneous tibioperoneal trunk and anterior tibial artery pseudoaneurysms

Abstract

Aneurysms of the tibioperoneal trunk and anterior tibial artery are extremely rare. There are only a few case reports of this entity, for which the majority are secondary to prior trauma or bacteremia and endocarditis. We describe a case of spontaneous pseudoaneurysms of the right anterior tibial artery and tibioperoneal trunk. The pseudoaneurysms were thrombosed on follow-up computed tomography angiography and the patient has been asymptomatic. The patient is being treated conservatively and remains asymptomatic at 1 year of follow-up.

Introduction

Aneurysms of the tibioperoneal trunk and anterior tibial artery are extremely rare. There are only a few case reports of this entity, for which the majority are secondary to prior trauma or bacteremia and endocarditis. We describe a case of spontaneous pseudoaneurysms of the right anterior tibial artery and tibioperoneal trunk.

Case report

A 54-year-old female with a history of left femoral artery aneurysm repair in February 2009 underwent a left external iliac to anterior tibial artery bypass on 23 April 2009 due to severe occlusive disease of the left femoral and profunda arteries. This was preceded by ilio-profunda and ilio-popliteal bypass procedures in addition to two thrombolysis procedures for occlusion. She presented for a computed tomography angiogram (CTA) of the abdomen and pelvis with bilateral lower extremity run-off on 20 September 2010 to evaluate the bypass and flow to the left lower extremity. At this time she had no complaints and all lower extremity pulses were present with good capillary refill. The CTA demonstrated occlusion of the left bypass graft and incidental findings of a right anterior tibial artery pseudoaneurysm measuring up to 7 mm and a right tibioperoneal trunk pseudoaneurysm measuring approximately 24 × 21 mm (Figure 1).

Figure 1.

(A) Axial source images from CTA; (B) 3-D volume-rendered images reconstructed from CTA; (C) 3-D volume-rendered and maximum intensity projection (MIP) images reconstructed from CTA.

An ultrasound of the lower extremities was performed on 23 September 2010 to assess for deep vein thrombosis and her left bypass graft. The anterior tibial and tibioperoneal trunk pseudoaneurysms were also visualized (Figure 2).

Figure 2.

(A) Grayscale ultrasound image of the anterior tibial artery demonstrating a hypoechoic collection communicating with the vessel. (B) Doppler image of the collection demonstrates the classic ‘yin–yang’ swirling of blood flow within the pseudoaneurysm. (C) Doppler image with waveform at the neck of the pseudoaneurysm demonstrates the to and fro flow within the sac.

The patient was asymptomatic and did not want treatment on her pseudoaneurysms unless absolutely medically necessary. Given the patient’s multiple prior interventions and her wishes, it was decided to treat the pseudoaneurysms conservatively and follow them with serial CTAs. The patient underwent a CTA in November 2010, which showed thrombosis of both the anterior tibial and the tibioperoneal trunk artery pseudoaneurysms (Figure 3). However, there was flow to the right foot via the anterior tibial artery and distal reconstitution of both the peroneal and the posterior tibial arteries.

Figure 3.

Axial source images from CTA.

The patient remained asymptomatic and had two follow-up CTAs in the interim period; the last, dated 19 May 2011, demonstrated persistent thrombosis of the pseudoaneurysms and patent flow to the right lower leg and foot.

Discussion

The pathogenesis of pseudoaneurysms is characterized by localized rupture of the arterial wall leading to blood extravasation, which is then walled off by the surrounding layers of connective tissue but maintains its communication with the arterial lumen through a neck. ¹

Pseudoaneurysms can be asymptomatic or may be present with swelling, bruising, pain, or neurological signs due to nerve compression, or rupture. ¹

Pseudoaneurysms of the anterior tibial artery and tibioperoneal trunk are exceedingly rare.^2–8 In addition, most if not all of these aneurysms are due to prior trauma or infection. Our patient denied any trauma and had no signs of overt bacteremia or endocarditis. An etiology that has been described as a cause of pseudoaneurysms is connective tissue disorders, which our patient may have but has not been diagnosed with as of yet. ⁸ This is corroborated by the history of a left femoral artery pseudoaneurysm and the incidental finding of right anterior tibial artery and right tibioperoneal trunk pseudoaneurysms a year later. She had undergone several laboratory tests for possible connective tissue disorders including lupus anticoagulant, homocysteine, fibrinogen, factors VIII, IX, and XI, protein C and S, beta 2-glycoprotein Ab, antithrombin, factor V Leiden, and PAI-1 gene polymorphism, which were all negative. In addition, she did not have any additional findings suggestive of a connective tissue disorder such as skin findings, body habitus or arteriomegaly.

The diagnosis of infrapopliteal true- and pseudoaneurysms can be made with multiple modalities. Noninvasive imaging with ultrasound can be performed, though popliteal artery aneurysms will be easier to detect given their likely larger size as compared to anterior tibial or tibioperoneal aneurysms. CTA or magnetic resonance angiography (MRA) can also depict infrapopliteal aneurysms very well. Three-dimensional volume-rendered reconstructions may be obtained with either of these modalities, which can provide exquisite detail of vascular anatomy and help in treatment planning. Finally, digital subtraction angiography (DSA) is considered the gold standard and can be performed prior to treatment for accurate assessment.

Complications of pseudoaneurysms include thrombosis, distal embolism, and, rarely, rupture. Critical limb ischemia is a rare but feared complication. For these reasons, immediate treatment for symptomatic patients and early treatment for asymptomatic patients has been recommended. Various treatment options have been described in the past, including: ultrasound-guided compression repair, long balloon inflation to occlude the pseudoaneurysm, embolization, covered stents, and surgery and bypass.^1,9–11

The decision not to treat the pseudoaneurysms was driven by the patient’s wishes as she was asymptomatic and had undergone several vascular procedures in the past. She agreed to be seen and followed-up with CTA every 6 months, and at the 1-year follow-up demonstrates no complications from her thrombosed anterior tibial and tibioperoneal trunk pseudoaneurysms. She also continues to maintain all three infrapopliteal vessels to the right lower leg and foot via the anterior tibial artery and reconstituted peroneal and posterior tibial artery.