Year : 2004 | Volume
: 14 | Issue : 2 | Page : 205--207
Bilateral persistent sciatic artery : Demonstration of the anomaly and its complications with intra arterial contrast enhanced spiral CT
KP SreeKumar, NK Prabhu, S Moorthy
Department of Radiology, Amrita Institute of Medical Sciences, Amrita Lane, Elamakkara, Cochin 682026, Kerala, India
K P SreeKumar
Department of Radiology, Amrita Institute of Medical Sciences, Amrita Lane, Elamakkara, Cochin 682026, Kerala
|How to cite this article:|
SreeKumar K P, Prabhu N K, Moorthy S. Bilateral persistent sciatic artery : Demonstration of the anomaly and its complications with intra arterial contrast enhanced spiral CT.Indian J Radiol Imaging 2004;14:205-207
|How to cite this URL:|
SreeKumar K P, Prabhu N K, Moorthy S. Bilateral persistent sciatic artery : Demonstration of the anomaly and its complications with intra arterial contrast enhanced spiral CT. Indian J Radiol Imaging [serial online] 2004 [cited 2020 Aug 6 ];14:205-207
Available from: http://www.ijri.org/text.asp?2004/14/2/205/28590
Persistent sciatic artery is a rare but well known clinically pertinent vascular anomaly that presents either as aneurysms in the buttocks or as ischemic peripheral vascular disease. The incidence, embryology and complications of this condition have been dealt with in detail in the literature. The slow forward flow in these ectatic vessels, the importance of delayed images and the requirement of large quantities of contrast are well known. We report a case of bilateral persistent sciatic arteries with bilateral aneurysm formation in the buttocks and a thrombo embolic occlusion distally. The routine angiogram failed to demonstrate the aneurysms and distal thrombo embolic occlusion, while an intra-arterial contrast enhanced spiral CT with the angiographic catheter in aorta documented this convincingly.
A seventy-year-old male patient with clinical features of acute on chronic peripheral vascular disease underwent digital subtraction angiogram, which showed large and ectatic bilateral internal iliac arteries. These arteries were seen extending into the lower limbs with aneurysm formation at the level of greater trochanter on both sides [Figure 1],[Figure 2]. The angiogram findings were consistent with bilateral persistent sciatic arteries. In delayed images a tortuous patent artery was seen up to mid thigh, distal to the aneurysm on the right side. On the left side no flow was apparent distal to the aneurysm [Figure 3]. In view of the suboptimal visualization of the distal arteries on the angiogram, the patient was immediately shifted to the computed tomography suite leaving the angiographic catheter in the abdominal aorta. An intra-arterial contrast enhanced spiral CT scan was done from mid abdomen level to the knee. A 50 second spiral acquisition with 8 mm thickness and 10 mm feed was obtained with biphasic contrast injection. A total of 130 ml contrast at 2.5ml/second. Scan delay was 4 seconds. This study showed the entire anatomy of the persistent sciatic arteries. Both the aneurysms were located at the level of greater trochanter.
Peripheral mural thrombi were noted in the aneurysms [Figure 4]. The artery distal to the aneurysm on the left side showed a long segment occlusion with reformation at mid thigh level. An intraluminal thrombus was apparent in the occluded segment in the axial images of the scan suggesting a thrombo embolic occlusion [Figure 5]. The artery distal to the aneurysm on the right side was normal. The sciatic arteries were seen continuing as popliteal arteries, which were normal. 3D reconstruction with surface shaded display performed with the spiral CT data, provided a better overall perspective of the vascular anatomy for the surgeon [Figure 6].
The sciatic artery is the primary axis artery of the lower limb. It arises from the dorsal root of the umbilical artery and runs along the dorsal surface of the lower limb. Rarely it persists on one or both sides. On routine angiography of the lower extremities, persistant sciatic artery has a reported frequency of .025 to .04%. Approximately 50% of reported cases are on the right side, 30% are bilateral and 20% are on the left side . There is a slight male preponderance. Unlike the fully developed femoral arteries, persistent sciatic arteries are prone to early atheromatous degeneration and aneurysm formation. Hypoplasia of the elastic components and the primitive arterial wall may be a factor in these pathological changes. The aneurysm formation is reported to occur with 15 to 40% frequency. The most frequent site of aneurysm is the region of greater trochanter.
Green published the first description of persistent sciatic artery way back in 1832 in the Lancet . Fagge reported the first account of an aneurysm of this vessel, the rupture of which resulted in a patient's death in 1864.
The embryology of this condition and the predisposition of the sciatic arteries to aneurysm formation and thromboembolic complications have been dealt in detail in literature ,.
Frequent mention has been made of the difficulty of routine angiograms to demonstrate distal flow in these vessels despite being totally patent due to the extreme slow flow. A large volume of contrast and extremely delayed films (sometimes as long as 50 seconds) after injection has been advocated to demonstrate the arterial tree from aorta to popliteal bifurcation. These problems often result in radiographs of poor quality, which may lead to incorrect diagnosis. In our case, the spiral CT scan with intra-arterial contrast injection overcame this problem. This technique has never been described earlier. An isolated report of an intravenous contrast enhanced 3D CT in persistent sciatic artery is available in literature.
Persistent sciatic artery is a rare vascular anomaly, which may be identified during a routine angiogram in a patient with suspected peripheral vascular disease. We feel from our experience, that on encountering such an anomaly during angiogram an intra-arterial contrast enhanced spiral CT scan with 3D reconstruction with the catheter in the abdominal aorta will be optimal for depiction of distal vessels and associated complications. Direct intra-arterial injection avoids the problem of contrast dilution associated with intra venous injections and a properly timed scan will counter the problem of slow blood flow in the ectatic arteries.
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