Posttraumatic pseudoaneurysm of medial plantar artery in a child : treatment with percutaneous thrombin injection

Pseudoaneurysms of the medial plantar artery are rare. The authors describe a case of a pseudoaneurysm of the medial plantar artery of a child who had suffered a penetrating laceration injury. Diagnosis can be confirmed using Doppler ultrasound and magnetic resonance angiography. As an alternative to the conventional surgery technique, percutaneous Doppler ultrasound-guided thrombin injection is a safe and effective treatment.


INTRODUCTION
Pseudoaneurysms are aneurysms whose walls are not comprised of the vessel's own parietal structures, which is what differentiates them from true aneurysms.They are very often the result of a communication with an artery after direct trauma, in which the lumen remains in contact with the pulsating hematoma, causing it to rupture.During its evolution, the clot that forms in the periphery of the hematoma tends to organize and, in conjunction with the cicatricial reaction of adjacent tissues, will form the walls of the aneurysm sac which, in turn, does not therefore have the elements that are characteristic of the artery wall. 1,2fter the posterior tibial artery leaves the inferior retinaculum of the flexor muscles, it divides to form the medial plantar artery and the lateral plantar artery.The second of these is more developed and is accompanied by the plantar nerve.The medial plantar artery follows the medial plantar fascia and is accompanied by the medial plantar nerve. 3ascular injuries leading to formation of a pseudoaneurysm in the plantar region of the foot are rare, despite the potential risk of localized trauma. 4seudoaneurysms of the lateral plantar artery have been reported after plantar fasciotomy, 5,6 osteotomy of the calcaneus 7 , fracture of the calcaneus 2 and after laceration of the foot in children. 8,9There are more publications dealing with pseudoaneurysms of the lateral plantar artery than of the medial plantar artery, probably because of its more superficial location. 10osttraumatic pseudoaneurysms of the medial plantar artery are rare and little has been published about them, but there are reports of onset after percutaneous implantation of pins to treat a Lisfranc fracture-luxation, 11 and after lacerating trauma of the foot. 10Time to diagnosis is variable and may be anything from 3 days to 5 years after the trauma. 12In this paper we report on the case of a medial plantar artery pseudoaneurysm secondary to a penetrating laceration trauma in a child.

CASE REPORT
The patient was an 8-year-old Caucasian male who suffered a trauma to the plantar surface of the right foot, caused by a sharp object (broken glass).The wound was sutured, bleeding was apparently controlled and there was no evidence of any residual foreign body.
Forty-five days later, the patient suffered swelling and pain in the right plantar foot that was exacerbated by bearing weight, walking and compression.The plantar pseudoaneurysm was treated with a Doppler ultrasound guided percutaneous injection of 300 units of dilated thrombin under sedation and local anesthetic.The thrombin was injected carefully until the flow inside the pseudoaneurysm was observed to cease.The thrombin dose administered was sufficient to totally and instantaneously occlude the lesion while maintaining patency of the native artery (Figure 3).The patient was already able to walk with no limitations on the third day after treatment and was free from complications or relapse at 8 months' follow-up (Figure 4).

DISCUSSION
S o m e p s e u d o a n e u r y s m s c a n r e s o l v e spontaneously, 13 but early diagnosis and treatment are nevertheless recommended to avoid potential harm; such as motor disorders or circulatory problems, ruptures and compression of bony structures, veins or adjacent nerves, leading to tarsal tunnel syndrome. 10,14,15etailed clinical history taking and physical examination are of fundamental importance for early diagnosis and should take account of time and mechanism of trauma. 8,10,16Pain, edema and hematoma are the initial symptoms of pseudoaneurysms.Persistence of pain after the trauma, a pulsating mass, systolic murmur, neurological signs and a fall in hemoglobin with no other obvious cause should suggest a diagnostic hypothesis of pseudoaneurysm. 10,12maging exams are indispensable to confirm and study these lesions.Diagnosis can be made by Doppler ultrasound, angiography and magnetic resonance angiography. 4,12Angiography is excellent for studying arterial anatomy, but is invasive and demands iodine contrast.On the other hand, Doppler ultrasound is a noninvasive method that is a valuable tool for studying lesions in extremities, but it is operator-dependent.Finally, magnetic resonance angiography offers higher spatial resolution of the lesion and higher sensitivity and specificity than angiography for studying the arterial tree and detecting peripheral vascular disease. 4,17,18urgical treatment of pseudoaneurysms may require ligature or arterial resection and repair with end-to-end anastomosis or vein grafts (generally from the great saphenous vein). 10,15Damage to adjacent structures and bleeding are possible complications of these techniques.
Non-surgical treatments, considered minimally invasive, can be accomplished using coils or percutaneous injection of thrombin or sclerosant

CONCLUSIONS
The Doppler ultrasound-assisted percutaneous thrombin injection technique used in this case of posttraumatic medial plantar artery pseudoaneurysm led to total resolution of the lesion and relief from symptoms.After eight months' follow-up, there have been no signs of complications or relapse of the lesion and the patient remains entirely asymptomatic.We can therefore conclude, in consonance with published data, that this technique should be considered for treatment of similar cases.substances (ethanol, for example), and have proven effective for resolving pseudoaneurysms. 15,19,20ndovascular treatments have also been used successfully, 10 but the inherent risks of these techniques must be considered: hemorrhage, pseudoaneurysm at the puncture site, ischemic complications and adverse reactions to the iodine contrast medium.
Ultrasound compression of the pseudoaneurysm neck alone can be technically challenging and uncomfortable for the patient, requiring compression times that vary from 10 to 300 minutes.In contrast, percutaneous ultrasound-guided thrombin injection requires simple compression of the aneurysm sac neck and offers rapid thrombosis. 21hrombin is a powerful coagulation induction agent that acts by converting fibrinogen in to fibrin, but dosages are not very well defined in the literature. 21It is very much worth employing realtime monitoring as the thrombin is injected into the aneurysm sac, using color flow ultrasound. 22The injection should be stopped as soon as flow into the aneurysm sac has ceased; generally occurring in a few seconds.If the injection is continued after flow has ceased within the aneurysm sac, there is a greater risk of thrombosis of the native artery caused by retrograde flow, exposing the artery to thrombin. 21 number of factors can impact on the method's safety and efficacy.Firstly, it appears that if the needle is positioned superficially within the centre of the aneurysm sac, at the pole most distant from the communicating orifice, clots are more likely to form and then migrate in the direction of the aneurysm neck. 21,23It is therefore preferable to inject into a region in which flow is predominantly inward, in order to minimize the risk of arterial embolism. 23t appears that complications related to thrombin injections are infrequent, with few reported cases of local infection, thrombosis and/or arterial thromboembolism or allergic reactions to thrombin.The most threatening of the known complications described in literature are arterial thrombosis and/ or thromboembolism, which can be prevented by avoiding injecting the thrombin close to or at the pseudoaneurysm neck. 21,23owadays noninvasive imaging exams offer excellent opportunities to study the lesion at low risk to the patient.While there is evidence that Doppler ultrasound-guided percutaneous thrombin injection offers the chance of safe, effective and minimally invasive treatment, detailed workup and rigorous attention to technical details play a fundamental role in successful treatment outcomes.

Figure 1 .
Figure 1.Magnetic resonance image showing the contrast highlighting the plantar region, suggesting a pseudoaneurysm..

Figure 2 .
Figure 2. Vascular echography scan, showing the pseudoaneurysm and its neck in the plantar region of the foot.

Figure 3 .
Figure 3. Image of pseudoaneurysm immediately after percutaneous thrombin injection, showing no blood flow in the interior.

Figure 4 .
Figure 4. Eight-month follow-up control vascular echography scan, showing a completely thrombosed pseudoaneurysm in regression.