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Herein, we present the case of a 22-year-old man who sustained a gunshot wound to a persistent sciatic artery. Endovascular stent management of the arterial injury obviated the need for surgical repair and revascularization in the presence of acute trauma. We believe this to be the 1st report of a completely endovascular repair of a penetrating traumatic injury to a persistent sciatic artery.
In addition, we review the origin and significance of persistent sciatic artery, and we discuss the treatment of sequelae that are associated with this vascular anomaly.
Persistent sciatic artery remains an infrequently encountered yet clinically important vascular problem. Originating as a persisting embryologic continuation of the internal iliac artery, the anomaly was first described in 1832,1 and the 1st report of an aneurysm of this vessel with fatal outcome was published in 1864.2 In addition to aneurysmal formation and rupture, complications of persistent sciatic artery include ischemia from occlusion and embolization. Sequelae that arise from persistent sciatic artery are usually reported as requiring surgical intervention. However, an endovascular approach in combination with surgery has been described for thrombolysis and endovascular occlusion,3,4 and stent-graft replacement of a sciatic artery aneurysm has been described.5 Here, we report the case of a patient who underwent a completely endovascular repair of a penetrating traumatic injury to a persistent sciatic artery. We also discuss various approaches to the treatment of persistent sciatic artery and the sequelae of this vascular anomaly.
In March 2003, a 22-year-old Cambodian man presented with multiple gunshot wounds to both thighs. One bullet was lodged in the soft tissues of the left gluteal region inferior to the sacrum. The patient had a cool, pulseless, paresthetic left foot. Arteriography showed a persistent and dominant left sciatic artery and a vestigial left superficial femoral artery (SFA) (Figs. 1 and and2).2). Disruption and occlusion of the persistent left sciatic artery was present, with extravasation in the proximal thigh. Distal reconstitution of the suprageniculate popliteal artery was present via a branch from the native vestigial SFA. There was 3-vessel runoff below the knee. The right lower extremity had normal anatomy without injury. The patient underwent percutaneous guidewire placement across the injured sciatic artery, with deployment of an 8 × 50-mm Wallgraft® covered stent (Boston Scientific Corporation; Natick, Mass) (Fig. 3). The extravasation was eliminated; good antegrade distal flow was seen, with mild arterial spasm of the distal sciatic artery. The patient did well and needed no further intervention from a vascular perspective. He was not kept on long-term anticoagulation. After his 1-week hospital stay, the patient was lost to follow-up despite multiple attempts at contact.
The sciatic artery is a continuation of the internal iliac artery, which, in early embryonic development, contributes the major vascular supply to the lower limb bud. By the 3rd month of intrauterine life, this artery involutes as the femoral artery develops, and a proximal remnant exists as the inferior gluteal artery.6–8 With an incidence of about 0.05%, the sciatic artery persists as a rare vascular anomaly that can be classified into 2 clinical types—“complete” or “incomplete”—on the basis of its relationship with the femoral artery.8–10 In the complete type, the SFA is hypoplastic, and the sciatic artery continues to the popliteal artery as a large vessel, without diminution. The sciatic artery runs through the greater sciatic foramen below the piriformis muscle to enter the thigh, inferior to the gluteus maximus, and courses alongside the sciatic nerve, sometimes within the neural sheath. It then dives posterior to the greater trochanter along the posterior aspect of the adductor magnus into the popliteal fossa, becoming the popliteal artery. This complete form of persistent sciatic artery—the more common of the 2 variants—occurs in approximately 75% of identified instances.10–11 In the rarer, incomplete type, the SFA remains the dominant inflow vessel into the popliteal artery, and the sciatic artery becomes hypoplastic in the thigh.
Our patient had the complete form of persistent sciatic artery, with a large anomalous vessel that became the popliteal artery and a rudimentary SFA that supplied collateral vessels to the popliteal artery (Fig. 2). Endovascular stenting proved a simple, expeditious, and minimally invasive solution to what would have been a difficult surgical problem. Had the endovascular treatment been unavailable, surgery would likely have entailed a transgluteal approach to proximal sciatic artery ligation, a lateral popliteal approach to ligation of the distal sciatic artery, and femoral–popliteal bypass with use of a standard 6-mm polytetrafluoroethylene (PTFE) prosthesis.
Although several complications can occur due to persistent sciatic artery, aneurysmal formation is the most common. Our patient had no aneurysm, but his traumatic sciatic artery injury nevertheless posed an interesting vascular challenge. After his acute vascular circumstance was alleviated, the ideal management would have been continued ultrasonographic surveillance of his sciatic artery, to watch for aneurysmal development and to ensure proper stent positioning. Unfortunately, this was not possible with this patient, who was lost to follow-up.
A sciatic artery aneurysm is distinguished from a gluteal artery aneurysm, which requires only ligation or endovascular thrombosis. Aneurysmal formation in the sciatic artery arises from early atheromatous degeneration; although the origins are not entirely clear, there may be extrinsic mechanical and intrinsic causes.3,7,8,12 Compression against the sacrospinal ligament and piriform muscle may occur. Furthermore, major arteries usually run on the flexor aspects of articulations, but the sciatic artery runs posteriorly in the buttocks and thigh and can become stretched. Sciatic artery aneurysms typically form under the gluteus maximus at the level of the greater trochanter. Arteriomegaly occurs frequently in persistent sciatic artery, and local embryologic congenital defects in the collagen–vascular makeup of the sciatic artery may be a factor.
Patients who have persistent sciatic artery most often present with limb ischemia, which often threatens the limbs13; to the best of our knowledge, ischemic presentation in the circumstance of trauma is heretofore unreported. Aneurysmal formation is signified by gluteal pain or by a painful, pulsatile mass in the buttocks. When the sciatic artery lies within the sciatic nerve sheath, the nerve is flattened and may cause leg pain that simulates sciatica.9,10 Acute limb ischemia in the presence of a sciatic artery aneurysm is usually caused by embolization, a condition that can be managed by embolectomy, distal bypass, or thrombolysis.3 Careful angiography can delineate the anatomy, reveal the type of persistent sciatic artery, and enable the evaluation of distal runoff. However, arteriograms that originate in the external iliac artery may miss a persistent sciatic artery, and the patient's clinical situation might then be misinterpreted as a simple SFA occlusion.
The treatment of sciatic artery aneurysm is generally accomplished by exclusion of the aneurysm via ligation or embolization. This alone is usually sufficient to treat an aneurysm in the incomplete variant of persistent sciatic artery; however, an aneurysm in the complete variant requires lower-extremity revascularization, which is usually achieved via femoral–popliteal bypass. Several proposed surgical approaches depend on the aneurysm's anatomy. If the aneurysmal neck is intrapelvic, it can be controlled via a trans- or extraperitoneal approach.6,10 If the neck is completely extrapelvic, a posterolateral curvilinear incision in the buttocks and splitting of the transgluteal muscle may be performed.10,13 A patent sciatic artery that has become aneurysmal can be treated by aneurysmorrhaphy with interpositional graft placement; however, there is still a risk of the artery's being stretched or compressed when the graft is seated. The more favored approach has been proximal and distal ligation of the aneurysm, with femoral–popliteal bypass.7,10 Percutaneous endovascular thrombosis of a sciatic artery aneurysm has also been performed.3–5 Another method is obturator bypass with exclusion of the sciatic artery aneurysm.14
Stent-grafts have been successfully used in traumatic arterial disruptions.15,16 In femoral aneurysm exclusion, preliminary information17 suggested that 1-year primary patency and secondary patency for the Wallgraft stent were each 100%; for popliteal aneurysms, primary patency was 69% and secondary patency was 92%. For popliteal aneurysms, use of the more flexible GORE VIABAHN® nitinol/PTFE endoprosthesis (W.L. Gore & Associates; Flagstaff, Ariz) resulted in a 1-year primary patency of 80% and secondary patency of 90%, and a 2-year primary patency of 77% and secondary patency of 87%.18 Although both endoprostheses can be effectively used in endovascular procedures, the Viabahn is currently approved in the United States for vascular and femoral use, but not for popliteal use, and the Wallgraft is approved only for tracheobronchial use.
In our patient, successful Wallgraft endovascular stent management of a traumatic sciatic artery injury obviated a difficult surgical procedure in the presence of acute trauma.
We thank Mercy Medical Center Biomedical Library, Redding, California, for assistance in preparing this manuscript.
Address for reprints: Fritz J. Baumgartner, MD, Surgery Associates, 3791 Katella Ave., #201, Los Alamitos, CA 90720. E-mail: firstname.lastname@example.org