- Email: [email protected]
Concurrent thrombosed aneurysmal sciatic artery and anomalous aortic arch
Concurrent thrombosed aneurysmal sciatic artery and anomalous aortic arch John Vedelago, MBBS, Bjoern Kitzing, MBBS, MD, Lisa Tarlinton, MBBS, Angela Li, MBBS, Kee Fung Chi, MBBS, BSc, and James Raleigh, MB ChB, FRANZCR, Camperdown, New South Wales, Australia A persistent sciatic artery is a rare developmental anomaly which may predispose to a range of vascular complications. We report a 60-year-old woman presenting with right lower limb ischemia. Computed tomography angiography revealed an aneurysmal right-sided sciatic artery occluded by thrombus. An aberrant right subclavian artery and anomalous common carotid origins were also incidentally discovered. It is unknown whether an association exists between a persistent sciatic artery and other congenital arterial abnormalities. This is the first case report, so far as we are aware, describing both such arterial anomalies coexisting in a patient. ( J Vasc Surg 2011;54:222-4.)
A persistent sciatic artery is a rare developmental anomaly which may predispose to a range of vascular complications. We report a 60-year-old woman presenting with right lower limb ischemia. Computed tomography angiography (CTA) revealed an aneurysmal right sciatic artery occluded by thrombus. An aberrant right subclavian artery and anomalous common carotid origins were also incidentally discovered. It is unknown whether an association exists between a persistent sciatic artery and other congenital arterial abnormalities. This is the first case report, so far as we are aware, describing both such arterial anomalies coexisting in a patient. CASE REPORT A 60-year-old woman underwent orthotopic liver transplantation for hepatocellular carcinoma and lamivudine-resistant hepatitis B, with an uncomplicated postoperative recovery. One week after her discharge from the hospital, she re-presented with symptoms of right lower limb claudication. Duplex ultrasound imaging at the time of presentation demonstrated short segmental occlusion of the right internal iliac, popliteal, and proximal tibioperoneal arteries. An ankle-brachial index was not measured. Because the patient had no documented clinical history of vascular disease, CTA was performed from the aortic arch to the feet to investigate a suspected thromboembolic source. CT imaging was performed with a LightSpeed Ultra 64-row CT scanner (GE Medical Systems, Milwaukee, Wisc). One hundred milliliters of nonionic iopromide contrast (Ultravist 300; Schering, Berlin, Germany) was injected at 4.5 mL/s. CTA revealed an aneurysmal anomalous artery coursing inferiorly from an abnormally large-caliber right internal iliac artery. This artery exited the pelvis through the greater sciatic notch caudal to the piriformis muscle and posteromedial to the sciatic From the Department of Radiology, Royal Prince Alfred Hospital. Competition of interest: none. Correspondence: Dr Kee Fung Chi, Royal Prince Alfred Hospital, Department of Radiology, Missenden Rd, Camperdown, NSW 2050, Australia (e-mail: [email protected]). 0741-5214/$36.00 Crown Copyright © 2011 Published by Elsevier Inc. on behalf of the Society for Vascular Surgery. All rights reserved. doi:10.1016/j.jvs.2010.12.011
222
nerve. It followed the course of the sciatic nerve, passing deep to gluteus maximus, and superficial to the superior and inferior gemelli and the obturator internus tendon. In the upper part of the posterior thigh, the artery continued inferiorly, adjacent and lateral to the sciatic nerve and lying between the biceps femoris and adductor magnus musculature. Complete luminal occlusion of the sciatic artery by soft tissue density material suggestive of thrombus was seen in the mid thigh (Fig 1). The artery was aneurysmal along its course in the posterior thigh, measuring approximately 3 cm in diameter. The aneurysmal persistent right sciatic artery was continuous with the right popliteal artery, which was similarly dilated. The right popliteal artery was patent, with flow demonstrated within its distal branches due to medial geniculate collaterals from a hypoplastic right superficial femoral artery. The left lower limb arterial system was unremarkable. The uppermost image of the CTA revealed an anomalous branching pattern of the aortic arch (Fig 2), including an aberrant right subclavian artery. A very short common trunk, from which both common carotid arteries arose, was also demonstrated (Fig 3). On further inquiry, the patient had been asymptomatic with respect to the right subclavian arterial anomaly. The patient underwent a right popliteal thrombectomy and femoropopliteal bypass with a long saphenous vein conduit and made an uneventful recovery.
DISCUSSION The first reported case of persistent sciatic artery was described in 1832 by Green.1 In this first reported case, no evidence of an ipsilateral superficial femoral artery was seen at dissection. In the primitive embryo, the sciatic artery provides the dominant arterial inflow to the lower limb. Normally, this artery regresses in the first few weeks of life, until only segmental remnants remain. Such remnants include the inferior gluteal artery, arterial rami concomitans of the sciatic nerve in addition to segments of the profunda femoris, popliteal, peroneal, and anterior tibial arteries.2 The precise factors that result in the persistence of this vessel are unknown. Persistent sciatic arteries frequently undergo aneurysmal degeneration associated with mural thrombus formation. This occurs in a relatively high proportion of patients
JOURNAL OF VASCULAR SURGERY Volume 54, Number 1
Vedelago et al 223
Fig 1. Left, Axial and (right) coronal images show a thrombosed right sciatic artery (arrow) in the posterior thigh.
Fig 2. Axial image shows a retroesophageal aberrant right subclavian artery (arrow).
and may lead to limb-threatening ischemia3 or necrosis resulting in amputation.4 A review of all published cases of sciatic arteries conducted by Schultz et al5 reported that the caliber of the ipsilateral superficial femoral artery represents the single most important predictive factor for aneurysm formation: the risk of aneurysm development is significantly higher with an ipsilateral superficial femoral artery which is of reduced diameter. Sciatic artery aneurysm rupture has also been reported.6 This abnormality may present particular difficulties in hip surgery7 and may also cause significant ischemia of the lower limb if ligated during renal transplant procedures.8 Findings on routine abdominal-pelvic CT scanning which may alert the radiologist to the presence of a persistent sciatic artery include an internal iliac arterial diameter greater than the ipsilateral external iliac artery, or a largecaliber arterial vessel seen passing through the greater sciatic notch. The anomaly may be observed unilaterally or bilaterally, and the ipsilateral superficial femoral artery is often concomitantly hypoplastic. Asymptomatic patients
Fig 3. Coronal view shows the patient’s anomalous common origin of the common carotid arteries (arrow).
with incidentally discovered sciatic arteries should be monitored through surveillance imaging because of the high incidence of complications associated with this anomaly. Owing to the infrequency of persistent sciatic artery anomalies, no set guidelines for follow-up imaging have been established. Given the propensity for aneurysmal degeneration, we recommend regular ultrasound monitoring of at least yearly intervals. The first case of an aberrant right subclavian artery was reported in 1794 by Bayford9 in a woman with lifelong dysphagia. The autopsy showed that the right subclavian artery originated distal to the left subclavian artery and
JOURNAL OF VASCULAR SURGERY July 2011
224 Vedelago et al
passed from left to right, between the trachea and esophagus. In normal development, the right seventh intersegmental artery and right fourth arch contribute to the formation of the right subclavian artery. An aberrant right subclavian artery arises due to involution of the right fourth arch, with the right seventh intersegmental artery attached to the descending aorta.10 Abnormalities at this site of attachment include aortic diverticula and atherosclerotic aneurysms. A remnant of the persistent right aortic arch, known as a Kommerell diverticulum, may also occur.10 We could find no reports of a persistent sciatic artery associated with a congenital aortic arch anomaly. We are unsure if this is because the aortic arch is not routinely examined in these patients and any coexisting anomalies present therefore go undetected. Authors invariably describe imaging of the abdominal aorta and lower limbs, but not the aortic arch.11,12 It is currently unknown if an association exists between a persistent sciatic artery and further developmental anomalies of the arterial system at other sites. In embryologic development, the sciatic artery arises at the 6-mm stage and involutes by the 22-mm stage.13 The primitive subclavian artery is recognizable at the 4- to 6-mm stage, and the right subclavian artery is formed by the 24-mm stage.14 It is therefore conceivable that a temporal link in their development exists, the interruption of which leads to these coincident abnormalities. Patients with sciatic arteries may be at increased risk of associated complications in the immediate postoperative period because all three components of Virchow’s triad— alteration to blood composition, flow, and vessel wall— may be disturbed. Slower flow occurs in aneurysmal sciatic arteries; this may be compounded when the artery is compressed during surgery. The artery’s vulnerable position in the posterior gluteal and thigh region may also, during prolonged postoperative bed rest and reduced mobility, result in longer periods of extrinsic compression than normal. This in turn may cause intermittent positional flow reduction and vessel wall changes that ultimately increase the risk of thrombosis. Prothrombotic changes to blood constituency in the postoperative period are well recognized and have been documented elsewhere.15 Factors that contributed to the development of thrombosis in this patient possibly included the 7-hour duration of surgery. In addition, correction of the patient’s preoperative thrombocytopenia secondary to her liver disease necessitated the intraoperative administration of large quantities of fresh frozen plasma, cryoprecipitate, and pooled platelets. CONCLUSION The persistent sciatic artery is a rare but important lower limb arterial variant. This vessel’s propensity for
aneurysmal degeneration commonly results in thrombotic or embolic complications that may threaten the limb. Factors in the immediate postoperative period that result in thrombosis may be more pronounced. CTA in this case proved a reliable and useful diagnostic modality in detecting the anomaly and its complications. An anomalous aortic arch branching pattern in this patient was also revealed. It is unknown if patients with persistent sciatic arteries exhibit an increased incidence of concomitant congenital arterial anomalies. Diagnostic and interventional radiologists should be familiar with the CT appearances of this variant, its anatomy, complications, and requirement for surveillance imaging. REFERENCES 1. Green PH. On a new variety of the femoral artery. Lancet 1832;1: 730-1. 2. Senior HD. The development of the arteries of the human lower extremity. Am J Anat 1919;25:55-9. 3. Ikezawa T, Naiki K, Moriura S, Ikeda S, Hirai M. Aneurysm of bilateral persistent sciatic arteries with ischemic complications: case report and review of the world literature. J Vasc Surg 1994;20:96-103. 4. Jung AY, Lee W, Chung JW, Song S-Y, Kim SJ, Ha J, et al. Role of computed tomographic angiography in the detection and comprehensive evaluation of persistent sciatic artery. J Vasc Surg 2005;42:678-83. 5. Shutze W, Garrett W, Smith B. Persistent sciatic artery: collective review and management. Ann Vasc Surg 1993;7:303-10. 6. Ishida K, Imamaki M, Ishida A, Shimura H, Miyazaki M. A ruptured aneurysm in persistent sciatic artery: a case report. J Vasc Surg 2005;42: 556-8. 7. Lindenbaum B, Sanders RJ, Steele G. Persistent sciatic artery and sciatic artery aneurysms: a hazard in hip surgery. Clin Orthop Rel Res 1978; 132:68-70. 8. Balachandra S, Singh A, Al-Ani O, Bagi N. Acute limb ischaemia after transplantation in a patient with persistent sciatic artery. Transplantation 1998;15:651-2. 9. Bayford D. An account of a singular case of obstructed deglutition. Mem Med Soc Lond 1974;2:271-86. 10. Bisognano JD, Young B, Brown JM, Gill EA, Fang FC, Zisman LS. Diverse presentation of aberrant origin of the right subclavian artery: two case reports. Chest 1997;112:1693-7. 11. McEnaney R, Baril D, Gupta N, Marone L, Makaroun M, Chaer R. Persistent sciatic artery aneurysm treated with concomitant tibial bypass and vascular plug embolization. J Vasc Surg 2009;50:915-8. 12. Jung AY, Lee W, Chung JW, Song SY, Kim SJ, Ha J, et al. Park role of computed tomographic angiography in the detection and comprehensive evaluation of persistent sciatic artery. J Vasc Surg 2005;42:678-83. 13. Mandell VS, Jaques PF, Delany DJ, Oberheu V. Persistent sciatic artery: clinical, embryologic, and angiographic features. AJR Am J Roentgenol 1985;144:245-9. 14. Cairney J. The anomalous right subclavian artery considered in the light of recent findings in arterial development. J Anat 1925;59:265-96. 15. Seyfer A, Seaber A, Dombrose F, Urbaniak J. Coagulation changes in elective surgery and trauma. Ann Surg 1981;193:210-3.
Submitted May 26, 2010; accepted Dec 1, 2010.
A persistent sciatic artery is a rare developmental anomaly which may predispose to a range of vascular complications. We report a 60-year-old woman presenting with right lower limb ischemia. Computed tomography angiography (CTA) revealed an aneurysmal right sciatic artery occluded by thrombus. An aberrant right subclavian artery and anomalous common carotid origins were also incidentally discovered. It is unknown whether an association exists between a persistent sciatic artery and other congenital arterial abnormalities. This is the first case report, so far as we are aware, describing both such arterial anomalies coexisting in a patient. CASE REPORT A 60-year-old woman underwent orthotopic liver transplantation for hepatocellular carcinoma and lamivudine-resistant hepatitis B, with an uncomplicated postoperative recovery. One week after her discharge from the hospital, she re-presented with symptoms of right lower limb claudication. Duplex ultrasound imaging at the time of presentation demonstrated short segmental occlusion of the right internal iliac, popliteal, and proximal tibioperoneal arteries. An ankle-brachial index was not measured. Because the patient had no documented clinical history of vascular disease, CTA was performed from the aortic arch to the feet to investigate a suspected thromboembolic source. CT imaging was performed with a LightSpeed Ultra 64-row CT scanner (GE Medical Systems, Milwaukee, Wisc). One hundred milliliters of nonionic iopromide contrast (Ultravist 300; Schering, Berlin, Germany) was injected at 4.5 mL/s. CTA revealed an aneurysmal anomalous artery coursing inferiorly from an abnormally large-caliber right internal iliac artery. This artery exited the pelvis through the greater sciatic notch caudal to the piriformis muscle and posteromedial to the sciatic From the Department of Radiology, Royal Prince Alfred Hospital. Competition of interest: none. Correspondence: Dr Kee Fung Chi, Royal Prince Alfred Hospital, Department of Radiology, Missenden Rd, Camperdown, NSW 2050, Australia (e-mail: [email protected]). 0741-5214/$36.00 Crown Copyright © 2011 Published by Elsevier Inc. on behalf of the Society for Vascular Surgery. All rights reserved. doi:10.1016/j.jvs.2010.12.011
222
nerve. It followed the course of the sciatic nerve, passing deep to gluteus maximus, and superficial to the superior and inferior gemelli and the obturator internus tendon. In the upper part of the posterior thigh, the artery continued inferiorly, adjacent and lateral to the sciatic nerve and lying between the biceps femoris and adductor magnus musculature. Complete luminal occlusion of the sciatic artery by soft tissue density material suggestive of thrombus was seen in the mid thigh (Fig 1). The artery was aneurysmal along its course in the posterior thigh, measuring approximately 3 cm in diameter. The aneurysmal persistent right sciatic artery was continuous with the right popliteal artery, which was similarly dilated. The right popliteal artery was patent, with flow demonstrated within its distal branches due to medial geniculate collaterals from a hypoplastic right superficial femoral artery. The left lower limb arterial system was unremarkable. The uppermost image of the CTA revealed an anomalous branching pattern of the aortic arch (Fig 2), including an aberrant right subclavian artery. A very short common trunk, from which both common carotid arteries arose, was also demonstrated (Fig 3). On further inquiry, the patient had been asymptomatic with respect to the right subclavian arterial anomaly. The patient underwent a right popliteal thrombectomy and femoropopliteal bypass with a long saphenous vein conduit and made an uneventful recovery.
DISCUSSION The first reported case of persistent sciatic artery was described in 1832 by Green.1 In this first reported case, no evidence of an ipsilateral superficial femoral artery was seen at dissection. In the primitive embryo, the sciatic artery provides the dominant arterial inflow to the lower limb. Normally, this artery regresses in the first few weeks of life, until only segmental remnants remain. Such remnants include the inferior gluteal artery, arterial rami concomitans of the sciatic nerve in addition to segments of the profunda femoris, popliteal, peroneal, and anterior tibial arteries.2 The precise factors that result in the persistence of this vessel are unknown. Persistent sciatic arteries frequently undergo aneurysmal degeneration associated with mural thrombus formation. This occurs in a relatively high proportion of patients
JOURNAL OF VASCULAR SURGERY Volume 54, Number 1
Vedelago et al 223
Fig 1. Left, Axial and (right) coronal images show a thrombosed right sciatic artery (arrow) in the posterior thigh.
Fig 2. Axial image shows a retroesophageal aberrant right subclavian artery (arrow).
and may lead to limb-threatening ischemia3 or necrosis resulting in amputation.4 A review of all published cases of sciatic arteries conducted by Schultz et al5 reported that the caliber of the ipsilateral superficial femoral artery represents the single most important predictive factor for aneurysm formation: the risk of aneurysm development is significantly higher with an ipsilateral superficial femoral artery which is of reduced diameter. Sciatic artery aneurysm rupture has also been reported.6 This abnormality may present particular difficulties in hip surgery7 and may also cause significant ischemia of the lower limb if ligated during renal transplant procedures.8 Findings on routine abdominal-pelvic CT scanning which may alert the radiologist to the presence of a persistent sciatic artery include an internal iliac arterial diameter greater than the ipsilateral external iliac artery, or a largecaliber arterial vessel seen passing through the greater sciatic notch. The anomaly may be observed unilaterally or bilaterally, and the ipsilateral superficial femoral artery is often concomitantly hypoplastic. Asymptomatic patients
Fig 3. Coronal view shows the patient’s anomalous common origin of the common carotid arteries (arrow).
with incidentally discovered sciatic arteries should be monitored through surveillance imaging because of the high incidence of complications associated with this anomaly. Owing to the infrequency of persistent sciatic artery anomalies, no set guidelines for follow-up imaging have been established. Given the propensity for aneurysmal degeneration, we recommend regular ultrasound monitoring of at least yearly intervals. The first case of an aberrant right subclavian artery was reported in 1794 by Bayford9 in a woman with lifelong dysphagia. The autopsy showed that the right subclavian artery originated distal to the left subclavian artery and
JOURNAL OF VASCULAR SURGERY July 2011
224 Vedelago et al
passed from left to right, between the trachea and esophagus. In normal development, the right seventh intersegmental artery and right fourth arch contribute to the formation of the right subclavian artery. An aberrant right subclavian artery arises due to involution of the right fourth arch, with the right seventh intersegmental artery attached to the descending aorta.10 Abnormalities at this site of attachment include aortic diverticula and atherosclerotic aneurysms. A remnant of the persistent right aortic arch, known as a Kommerell diverticulum, may also occur.10 We could find no reports of a persistent sciatic artery associated with a congenital aortic arch anomaly. We are unsure if this is because the aortic arch is not routinely examined in these patients and any coexisting anomalies present therefore go undetected. Authors invariably describe imaging of the abdominal aorta and lower limbs, but not the aortic arch.11,12 It is currently unknown if an association exists between a persistent sciatic artery and further developmental anomalies of the arterial system at other sites. In embryologic development, the sciatic artery arises at the 6-mm stage and involutes by the 22-mm stage.13 The primitive subclavian artery is recognizable at the 4- to 6-mm stage, and the right subclavian artery is formed by the 24-mm stage.14 It is therefore conceivable that a temporal link in their development exists, the interruption of which leads to these coincident abnormalities. Patients with sciatic arteries may be at increased risk of associated complications in the immediate postoperative period because all three components of Virchow’s triad— alteration to blood composition, flow, and vessel wall— may be disturbed. Slower flow occurs in aneurysmal sciatic arteries; this may be compounded when the artery is compressed during surgery. The artery’s vulnerable position in the posterior gluteal and thigh region may also, during prolonged postoperative bed rest and reduced mobility, result in longer periods of extrinsic compression than normal. This in turn may cause intermittent positional flow reduction and vessel wall changes that ultimately increase the risk of thrombosis. Prothrombotic changes to blood constituency in the postoperative period are well recognized and have been documented elsewhere.15 Factors that contributed to the development of thrombosis in this patient possibly included the 7-hour duration of surgery. In addition, correction of the patient’s preoperative thrombocytopenia secondary to her liver disease necessitated the intraoperative administration of large quantities of fresh frozen plasma, cryoprecipitate, and pooled platelets. CONCLUSION The persistent sciatic artery is a rare but important lower limb arterial variant. This vessel’s propensity for
aneurysmal degeneration commonly results in thrombotic or embolic complications that may threaten the limb. Factors in the immediate postoperative period that result in thrombosis may be more pronounced. CTA in this case proved a reliable and useful diagnostic modality in detecting the anomaly and its complications. An anomalous aortic arch branching pattern in this patient was also revealed. It is unknown if patients with persistent sciatic arteries exhibit an increased incidence of concomitant congenital arterial anomalies. Diagnostic and interventional radiologists should be familiar with the CT appearances of this variant, its anatomy, complications, and requirement for surveillance imaging. REFERENCES 1. Green PH. On a new variety of the femoral artery. Lancet 1832;1: 730-1. 2. Senior HD. The development of the arteries of the human lower extremity. Am J Anat 1919;25:55-9. 3. Ikezawa T, Naiki K, Moriura S, Ikeda S, Hirai M. Aneurysm of bilateral persistent sciatic arteries with ischemic complications: case report and review of the world literature. J Vasc Surg 1994;20:96-103. 4. Jung AY, Lee W, Chung JW, Song S-Y, Kim SJ, Ha J, et al. Role of computed tomographic angiography in the detection and comprehensive evaluation of persistent sciatic artery. J Vasc Surg 2005;42:678-83. 5. Shutze W, Garrett W, Smith B. Persistent sciatic artery: collective review and management. Ann Vasc Surg 1993;7:303-10. 6. Ishida K, Imamaki M, Ishida A, Shimura H, Miyazaki M. A ruptured aneurysm in persistent sciatic artery: a case report. J Vasc Surg 2005;42: 556-8. 7. Lindenbaum B, Sanders RJ, Steele G. Persistent sciatic artery and sciatic artery aneurysms: a hazard in hip surgery. Clin Orthop Rel Res 1978; 132:68-70. 8. Balachandra S, Singh A, Al-Ani O, Bagi N. Acute limb ischaemia after transplantation in a patient with persistent sciatic artery. Transplantation 1998;15:651-2. 9. Bayford D. An account of a singular case of obstructed deglutition. Mem Med Soc Lond 1974;2:271-86. 10. Bisognano JD, Young B, Brown JM, Gill EA, Fang FC, Zisman LS. Diverse presentation of aberrant origin of the right subclavian artery: two case reports. Chest 1997;112:1693-7. 11. McEnaney R, Baril D, Gupta N, Marone L, Makaroun M, Chaer R. Persistent sciatic artery aneurysm treated with concomitant tibial bypass and vascular plug embolization. J Vasc Surg 2009;50:915-8. 12. Jung AY, Lee W, Chung JW, Song SY, Kim SJ, Ha J, et al. Park role of computed tomographic angiography in the detection and comprehensive evaluation of persistent sciatic artery. J Vasc Surg 2005;42:678-83. 13. Mandell VS, Jaques PF, Delany DJ, Oberheu V. Persistent sciatic artery: clinical, embryologic, and angiographic features. AJR Am J Roentgenol 1985;144:245-9. 14. Cairney J. The anomalous right subclavian artery considered in the light of recent findings in arterial development. J Anat 1925;59:265-96. 15. Seyfer A, Seaber A, Dombrose F, Urbaniak J. Coagulation changes in elective surgery and trauma. Ann Surg 1981;193:210-3.
Submitted May 26, 2010; accepted Dec 1, 2010.