Persistent sciatic artery aneurysm: A rare cause of acute limb ischemia

Pranay Pawar; Achintya Sharma; MK Ayyappan; Radhakrishnan Raju

doi:10.4103/cjhr.cjhr_122_17

CASE REPORT

Year : 2018 | Volume : 5 | Issue : 2 | Page : 155-156

Persistent sciatic artery aneurysm: A rare cause of acute limb ischemia

Pranay Pawar, Achintya Sharma, MK Ayyappan, Radhakrishnan Raju
Department of Vascular Surgery, Sri Ramachandra University, Chennai, Tamil Nadu, India

Date of Web Publication

9-Apr-2018

Correspondence Address:
Pranay Pawar
Department of Vascular Surgery, Sri Ramachandra University, Chennai, Tamil Nadu
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/cjhr.cjhr_122_17

Abstract

Persistent sciatic artery (PSA) is a rare but pertinent clinical entity that may pose a threat to the viability of the lower extremity. The incidence of PSA has been estimated to be between 0.01% and 0.05%. PSAs are prone to high incidence of aneurysm formation, thrombosis, distal embolization, and rupture. Early detection of a PSA as the main vascular supply to the lower limb helps in early surgery and avoids potential severe complications such as limb ischemia. We report a case of a female patient who was diagnosed with a case of lumbar disc compression and sciatica but had a PSA aneurysm with thrombosis and distal embolization leading to acute limb ischemia.

Keywords: Acute limb ischemia, limb salvage, persistent sciatic artery aneurysm

How to cite this article:
Pawar P, Sharma A, Ayyappan M K, Raju R. Persistent sciatic artery aneurysm: A rare cause of acute limb ischemia. CHRISMED J Health Res 2018;5:155-6

How to cite this URL:
Pawar P, Sharma A, Ayyappan M K, Raju R. Persistent sciatic artery aneurysm: A rare cause of acute limb ischemia. CHRISMED J Health Res [serial online] 2018 [cited 2023 Apr 1];5:155-6. Available from: https://www.cjhr.org/text.asp?2018/5/2/155/229585

Introduction

Persistent sciatic artery (PSA) is an extremely rare embryologic anomaly. It is seen in approximately 0.01%–0.05% of patients and is bilateral in 22%–25% of cases.^[1] It is a branch of the umbilical artery and is the main arterial supply to the lower limb during the 6 mm stage of embryonic development. At the 22 mm stage, it involutes and the superficial femoral artery (SFA) takes over the arterial supply of the leg. Persistence of the PSA leads to it developing as the main arterial supply of the leg as an enlarged and tortuous vessel prone to aneurysms, thrombosis, rupture, and distal embolization.^[2] Due to its rarity, recognition of this entity is usually delayed, and the ensuing complications can be catastrophic for the patient, as we have detailed in the following report.

Case Report

A 55-year-old female patient presented with complaints of lower back and right leg pain for a day before admission. She was diagnosed with sciatica and was admitted under spine surgery for the same. A day later, her right lower extremity was found to be cold and cyanosed (Rutherford Class IIB). She had a weak femoral pulse and absent popliteal and distal pulses. She also had a pulsating mass in the right gluteal region. Her computed tomography angiogram showed the right internal iliac artery continuing into the thigh through the greater sciatic notch as the PSA and continuing as the popliteal artery. She also had a 6.2 cm × 4.4 cm thrombosed aneurysm present between the piriformis and gluteus maximus with thrombosis of the popliteal artery and the tibial-peroneal trunk. The SFA was hypoplastic and terminated in the lower thigh [Figure 1]. She was undertaken for a popliteal thrombectomy and four-compartment fasciotomy. Her below-knee muscles were not viable, and she underwent a right above-knee amputation and a sciatic artery aneurysm ligation through a transgluteal approach at a later date.

Figure 1: Reconstructed computed tomography angiogram of abdominal aorta and bilateral lower limb showing the right internal iliac artery continuing into the thigh through the persistent sciatic artery and continuing as the popliteal artery. A 6.2 cm × 4.4 cm thrombosed aneurysm is present with thrombosis of the popliteal artery and the tibial-peroneal trunk. The superficial femoral artery is hypoplastic and terminates in the lower thigh

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Discussion

The sciatic artery is the main axial artery in the embryonic phase and usually involutes by the 22 mm stage, and the femoral artery takes over the main blood supply of the lower limbs. When the PSA is present in adults, it courses inferior to the gluteus maximus, posterior to the greater trochanter of the femur, and along the posterior aspect of the adductor magnus into the popliteal fossa, where it becomes the popliteal artery. It is usually tortuous, enlarged, and prone to aneurysmal changes, thrombosis, rupture, and distal embolization. Aneurysmal changes are present in 44-61% of PSA's and are due to anatomical course, over stretching during flexion of the hip and reduced elastin in a congenital arterial wall.^[3],[4] The diagnosis of a PSA demands a high level of suspicion by the physician, besides being dependent on the patient's clinical presentation and physical examination.^[5] The presence of an absent or diminished femoral pulse with a palpable popliteal pulse is pathognomic of a PSA (Cowie's sign), and the finding of a pulsatile gluteal swelling along with it is definitive of a PSA aneurysm.^[6] The diagnosis is usually confirmed by an angiogram. A study by Pillet et al. described five types of PSAs as follows:

Complete PSA with a normal femoral artery
Complete PSA with an incomplete femoral artery
Incomplete upper PSA with a normal femoral artery
Incomplete lower PSA with a normal femoral artery
PSA originating from the middle sacral artery.

The treatment options for PSA aneurysm vary according to the presentation. For asymptomatic cases, regular follow-up with physical examination and duplex scanning is sufficient. If the femoral artery is complete or provides sufficient blood supply to the lower limb, the PSA may be ligated. However, if the femoral artery is hypoplastic, a distal bypass will have to be done followed by ligation of the PSA. In acute settings, a thrombectomy followed by a staged revascularization/exclusion procedure has to be performed. However, it is associated with a 10%–20% amputation rate.^[4],[6] A hybrid approach maybe also used with a distal bypass followed by endovascular isolation of the PSA aneurysm with coils and plugs in a retrograde fashion.^[7] Unfortunately, in our case, we could not salvage the limb due to delay in diagnosis of this entity. Being aware of this entity and its treatment options will ensure early management and reduction in complications.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

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