Persistent sciatic artery (PSA): An unusual but interesting and clinically pertinent vascular anomaly.

Abstract

Learning objectives: PSA is an unusual vascular anomaly and because of its vulnerable position, it is associated with a high risk of aneurysm formation and its complications. The following case and a review of published articles are aimed at increasing the awareness of the existence of this condition, imaging findings and treatment options available. Background: The sciatic artery is the primary arterial supply of the lower limb bud during early embryonic development, which typically regresses after the first trimester when the femoral arterial system assumes this role. Remnants persist as the peroneal, popliteal and inferior gluteal arteries, but in up to 0.05% of people the artery in its entirety may persist in either a complete (large calibre) or incomplete (narrow calibre) form. Patients could remain asymptomatic, or may present with consequences of aneurysm formation including: pulsating mass, buttock pain, acute or chronic lower limb ischemia. Imaging findings: In our case who presented with left lower limb claudication, Magnetic Resonance Angiography (MRA) showed a large left-sided PSA, originating at the left internal iliac artery and passing out of the pelvis through the greater sciatic notch, with a small calibre left superficial femoral artery. Initial CT angiography (CTA) supplemented the MRA findings by excluding an aneurysm in the buttock and demonstrated thrombus within popliteal artery. But follow up CTAs, two and three years later, illustrated thrombosed aneurysm of proximal PSA. Conclusion: PSA is a rare but clinically significant vascular anomaly for both vascular interventionists and surgeons. Failure to identify a PSA may lead to unnecessary bypass a low calibre superficial femoral artery. Although MRA is a safe and effective modality for investigating lower limb ischemic symptoms, but CTA is complementary and should be performed prior to invasive procedures. Treatment options depend on the type and symptoms and can be surgical or interventional.<br />