INTERVENTIONAL NEURORADIOLOGY
VOLUME 21 - No. 2 APRIL 2015 ISSN 1591-0199 Online ISSN 2385-2011
neuroradiology solutions www.abmedica.it
Volume 21, No. 2, Pages 141 - 284, 2015
ab medica s.p.a.
Via nerviano, 31 - 20020 Lainate (MI) tel +39 02 933051 - fax +39 02 93305400 [email protected]
Journal of Peritherapeutic Neuroradiology, Surgical Procedures and Related Neurosciences Official Journal of: WFITN - World Federation of Interventional and Therapeutic Neuroradiology AAFITN - Asian & Australasian Federation of Interventional & Therapeutic Neuroradiology SAWITN - South American Working Group in Interventional and Therapeutic Neuroradiology The Chinese INR Coordinating Committee of the Chinese Doctor Association INSHCM - Interventional Neuroradiology Society of HCM City, Viet Nam Journal sponsored by JSNET - Japanese Society of Neuro Endovascular Therapy FIO - Italian Federation of Ozone Therapy Interventional Neuroradiology is published in cooperation with the American Journal of Neuroradiology
Case Report
Lumbar spinal epidural arteriovenous fistula with perimedullary venous drainage after endoscopic lumbar surgery
Interventional Neuroradiology 2015, Vol. 21(2) 249–254 ! The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1591019915583212 ine.sagepub.com
Toshiharu Murakami1, Ichiro Nakagawa1, Takeshi Wada2, Kimihiko Kichikawa2 and Hiroyuki Nakase1
Abstract Spinal epidural arteriovenous fistulas (AVFs) with perimedullary venous drainage are rare. This report describes a case of lumbar epidural AVF in a patient with a history of endoscopic lumbar discectomy at the same level 8 years prior to presenting with progressive myelopathy secondary to retrograde venous reflux into the perimedullary vein. A 69-year-old man presented with progressive lower extremity weakness and sensory disturbance and loss of sphincter control 8 years after endoscopic lumbar discectomy for a disc herniation at L4–5 level. Magnetic resonance imaging showed spinal cord edema and dilated intradural perimedullary vessels. Spinal angiography revealed an epidural AVF at the site of the previous endoscopic lumbar surgery with intradural perimedullary venous drainage. The fistula was successfully occluded via endovascular transarterial embolization, and the patient had stabilization of his neurological deficits. Lumbar spinal epidural AVFs, especially those associated with iatrogenic trauma, are rare. Endoscopic surgical procedure can occlude the epidural venous plexus and disturb venous drainage, thereby inducing local venous hypertension and leading to epidural AVF with perimedullary venous drainage. This type of pathology should be considered within the differential diagnosis of delayed neurological deterioration after spinal surgery.
Keywords Endoscopic lumbar surgery, epidural arteriovenous fistula, perimedullary venous drainage, transarterial embolization
Introduction Spinal epidural arteriovenous fistulas (AVFs) are rare among spinal vascular lesions.1–10 The precise mechanisms responsible for the development and growth of epidural and dural AVFs remain unclear; however, some reports suggest that there is a relationship between these entities and prior surgery or trauma.11–16 Spinal epidural AVFs are generally thought to present with benign clinical symptoms, such as radiculopathy. However, spinal epidural AVFs can cause acute paraplegia due to retrograde venous reflux into the medullary veins with venous congestion and consecutive intramedullary edema.17 The present report describes a case of a patient with a history of a lumbar disc herniation at L4–5 level who had undergone endoscopic lumbar discectomy 8 years prior. He presented with progressive myelopathy secondary to reflux into the perimedullary vein from an epidural AVF.
left L4/L5 lumbar vertebrae herniated intervertebral disk at another hospital 8 years earlier. He noted loss of strength of both lower limbs and sensory disturbance beginning 10 months prior to presentation to our department. Symptoms had gradually progressed to the point where he had difficulty walking and he had bladder dysfunction. On magnetic resonance (MR) imaging, high signal intensity was present in the lower portion of the spinal cord and serpentine perimedullary signal voids were shown in the T2-weighted image (Figure 1(a)). The images showed centromedullary edema below the mid-thoracic level as well as some minimally enlarged veins around the conus medullaris (Figure 1(b)). Sagittal and axial enhanced-computed tomography (CT) images showed a venous pouch in the posterior surface of the L4 vertebral body and showed dilated perimedullary veins (Figure 1(c, d).
1
Case report History and examination A 69-year-old man had previously undergone endoscopic herniated intervertebral disk enucleation for
Department of Neurosurgery, Nara Medical University, Nara, Japan Department of Radiology, Nara Medical University, Nara, Japan
2
Corresponding author: Ichiro Nakagawa, Department of Neurosurgery, Nara Medical University, 840 Shijo-cho, Kashihara City, Nara 634-8522, Japan. Email: [email protected]
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Interventional Neuroradiology 21(2)
Figure 1. Images from the patient upon admission. Sagittal T2-weighted MR image at the lumbar (a) and the lower thoracic (b) spine shows hyperintensity within the cord (arrowhead) and shows the presence of multiple flow voids on the surface of the cord (arrows). Sagittal (c) and axial (d) enhanced-CT shows a venous pouch in the posterior L4 vertebral body and shows dilated vessels (arrowhead). The AVF draining to the perimedullary vein (white arrow) at the L1 level through intradural vein (black arrow) (c).
Intra-arterial spinal angiography was performed. Angiography of the bilateral segmental L4 artery showed pathological opacification of the epidural venous space with very late reflux in an ascending intradural perimedullary vein. Selective angiography of the dorsal somatic branch of the right (Figure 2(a)) and left (Figure 2(b)) radicular artery at the level of L4 showed the AVF shunted to the epidural venous pouch and then drained through the intradural vein into the perimedullary vein at the level of L1 without epidural drainage. An epidural AVF was fed by the bilateral dorsal somatic branch of the fourth lumber segmental artery and the fistulas gathered to an epidural venous pouch draining into the perimedullary vein through an intradural vein located at cauda equina. No other feeding supply to the fistula was depicted on angiography. This case was regarded as spinal epidural AVF with
multiple shunt points around the venous pouch in the epidural venous plexus.
Treatment After discussion with the neurosurgical and endovascular teams, we planned endovascular transarterial embolization to eliminate the fistulas. The endovascular procedure was performed after obtaining written informed consent from the patient. Under local anesthesia, Marathon flow-directed microcatheters (Covidien, Dublin, Ireland) were introduced into the right dorsal somatic branch of the fourth lumber segmental artery as close as possible to the shunt points. The feeding arteries, venous pouch, and proximal portion of the draining veins were embolized with a mixture of n-butyl cyanoacrylate and lipiodol (Figure 2(c)).
Murakami et al.
251
Figure 2. Selective angiography of the dorsal somatic branch (black arrows) of the right (a) and left (b) radicular artery at the level of L4 shows epidural AVFs with an epidural venous pouch (arrowhead) draining through the intradural vein into the perimedullary vein (white arrows). Transarterial embolization with NBCA was performed via the dorsal somatic branch of the right radicular artery (black arrow) (c). Complete obliteration of the fistula is seen after embolization (d).
Subsequently, transarterial embolization of the left dorsal somatic branch was performed in the same manner. The final angiogram revealed complete obliteration of the fistula (Figure 2(d)). Sagittal and axial CT after transarterial embolization showed a glue cast in the ventral epidural pouch (Figure 3(a, b)).
Postoperative course The patient’s neurological symptoms gradually improved, and his paresthesia of the lower extremities, gait disturbance, and urinary sphincter dysfunction resolved. By the 1-year follow-up time point, MR imaging revealed disappearance of the spinal cord swelling and the signal voids around the spinal cord (Figure 3(c)).
Discussion Spinal epidural AVFs, especially those associated with iatrogenic trauma, are rare, and only a few case reports have been published.11–16 We have summarized seven cases of spinal epidural AVFs with a history of the iatrogenic injury (including the present case) in Table 1. Most cases involved elderly males, were associated with perimedullary venous reflux causing congestive myelopathy, and were associated with the development of epidural AVFs a few months to a few years after surgery. The present case is the first report of lumbar epidural AVF in a patient with a history of endoscopic lumbar discectomy at the same level who presented with congestive myelopathy 8 years after surgery, although most
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Figure 3. Sagittal (a) and axial (b) CT after embolization shows glue cast in the ventral epidural pouch (arrowhead). Sagittal T2-weighted MR image showing disappearance of the spinal cord swelling and showing multiple flow voids on the spinal cord (c).
reported cases of epidural AVFs occurred after laminectomy surgery. Unlike spinal dural AVFs, epidural AVFs are located in the ventral epidural space, are fed by multiple epidural branches, and drain into the ventral epidural venous pouch. Further, they are generally thought to present with benign clinical symptoms, such as radiculopathy. Geibprasert et al. proposed a new classification of dural AVFs according to craniospinal epidural venous anatomy.11 Populations with ventral epidural AVFs had a female predominance, a benign clinical presentation, and a lower rate of spinal cord venous reflux when compared with that of patients with lateral epidural AVFs. However, some patients developed extensive thrombosis of the normal epidural outlets that leads to retrograde drainage to perimedullary veins as a variant of ventral epidural AVFs. The present case can be classified as ventral epidural AVF because of the shunt location, the perimedullary venous reflux without epidural drainage, and the presentation with congestive myelopathy. Kiyosue et al. clearly described the classification of spinal ventral epidural AVFs of the lumbar spine based on the drainage type.15 Dorsal somatic branches, which supply the vertebral body, were the primary feeding branches to the epidural AVFs, forming a shunted pouch that was located in the ventral epidural space. They described three types of venous drainage routes, perimedullary venous drainage (PM), paravertebral drainage (PV), and combined perimedullary and paravertebral venous drainage (PMPV). In PM-type AVFs, the epidural AVFs shunted to an epidural venous pouch and then drained through the radiculomedullary vein into the perimedullary vein. The PVtype AVFs drained via the radiculoemissary vein into the paravertebral veins. The present case can be classified as PM-type AVF because the AVF shunted to the
epidural venous pouch at the level of L4 and then drained through the paravertebral vein into the perimedullary vein at the level of L1 without epidural drainage. We assume that the complex venous flow into the perimedullary vein through the epidural venous pouch in the present case was due to previous endoscopic lumbar discectomy at this level that may have injured the epidural connective tissue involving the epidural veins, predisposing the patient to venous thrombosis and leading to formation of an AVF and complex retrograde venous drainage into the perimedullary vein, although it is difficult to exclude a possibility that the epidural AVF already existed and, following endoscopic discectomy, might have contributed to the change in behavior of the fistula. Postoperative neurologic deterioration after lumbar surgery can arise from a variety of causes, including residual disc fragments, large vessel injury, nerve root damage, and epidural hematomas.12,16,18 However, epidural fistulas causing a congestive myelopathy are very rare. Only four cases of epidural AVFs after laminectomy surgery have been published; only one case (the present case) after endoscopic lumbar discectomy has been reported (Table 1).14,17,19–21 The precise mechanisms responsible for the development and growth of epidural and dural AVFs remain unclear. However, venous hypertension and increased flow of blood into the low-resistance venous system can promote the growth of microscopic AVFs, which stimulates the release of angiogenic factors in experimental models.22,23 Lumbar decompression surgery, including endoscopic discectomy, could occlude the epidural venous plexus and disturb venous drainage, thereby inducing local venous hypertension and leading to epidural AVF. The mechanism related to the fistula formation would be essentially the same in both open surgical and endoscopic microdiscectomy, although
M
M
M
68
37
69
L4
L4-5
L3
T12
L3
L3
S1
Level
MED
Falling and laminectomy
T12 fracture Laminectomy (T11-L1) Prostatectomy
Laminectomy (L2/3,L3/4)
Laminectomy (L3/4)
Removal of AAA
Iatrogenic trauma
8 years
4 months
3 months
1 year
4 years, 8 months
2 years
4 years
Duration
Radiculopathy, bladder/ bowel incontinence Lower extremity weakness and paresthesia, loss of sphincter control
Myelopathy
Left lower extremity numbness Lower extremity painful paresthesia, gait disturbance Myelopathy
Leg weakness
Neurology
AAA: Abdominal aortic aneurysm; MED: micro-endoscopic discectomy; TAE: transarterial embolization; TVE: transvenous embolization.
F
M
65
60
M
68
Sliva N Jr. et al. (2007) Sliva N Jr. et al. (2007) Leonardo R et al. (2011) Present case
M
72
Pirouzmand F et al. (1997) Khaldi A et al. (2009) LIM SM et al. (2009)
Gender
Age (years)
Author (year)
Table 1. Reported cases of spinal epidural arteriovenous fistula with a history of an iatrogenic injury.
TAE TAE
Perimedullary vein
TVE 3
TAE
TAE
Surgery
TAE þ Surgery
Treatment
Epidural vein
Perimedullary vein
Perimedullary vein
Perimedullary vein
Perimedullary vein Paravertebral vein Perimedullary vein
Draining route
Good recovery
Good recovery
Lower limb deficit, Dysesthesia Good recovery
Good recovery
Good recovery
Good recovery
Outcome
Murakami et al. 253
254 endoscopic microdiscectomy is thought to be a less invasive treatment method. The therapeutic goal in the management of epidural AVFs is to obliterate the fistulous communication between the feeding artery and the draining vein by means of surgery or endovascular embolization. The majority of epidural AVFs with PM-type venous drainage can be successfully treated by transarterial embolization with either Onyx or glue,24 although transvenous embolization or surgical resection may also be possible.11,15 The patient in the present case was treated with transarterial embolization from the bilateral dorsal somatic branch using glue and obtained complete obliteration of the fistulas. Precise evaluation of the angioarchitecture of epidural AVFs enables successful endovascular embolization of the fistulas. This is the first description of lumbar epidural AVF in a patient with a history of endoscopic lumbar discectomy at the same level who presented with congestive myelopathy. Spinal epidural AVFs, especially those associated with iatrogenic trauma, are rare and difficult to diagnose. Although endoscopic lumbar surgery is thought to be a less invasive treatment method, lumbar epidural AVF should be considered after careful evaluation of images to improve clinical outcomes. Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Conflict of interest None declared.
References 1. Arnaud O, Bille F, Pouget J, et al. Epidural arteriovenous fistula with perimedullary venous drainage: Case report. Neuroradiology 1994; 36: 490–491. 2. Asai J, Hayashi T, Fujimoto T, et al. Exclusively epidural arteriovenous fistula in the cervical spine with spinal cord symptoms: Case report. Neurosurgery 2001; 48: 1372–1375. 3. Cognard C, Semaan H, Bakchine S, et al. Paraspinal arteriovenous fistula with perimedullary venous drainage. Am J Neuroradiol 1995; 16: 2044–2048. 4. Clarke MJ, Patrick TA, White JB, et al. Spinal extradural arteriovenous malformations with parenchymal drainage: Venous drainage variability and implications in clinical manifestations. Neurosurg Focus 2009; 26: E5. 5. Goyal M, Willinsky R, Montanera W, et al. Paravertebral arteriovenous malformations with epidural drainage: Clinical spectrum, imaging features, and results of treatment. Am J Neuroradiol 1999; 20: 749–755. 6. Hemphill JC III, Smith WS and Halbach VV. Neurologic manifestations of spinal epidural arteriovenous malformations. Neurology 1998; 50: 817–819. 7. Krings T, Mull M, Bostroem A, et al. Spinal epidural arteriovenous fistula with perimedullary drainage. Case report and pathomechanical considerations. J Neurosurg Spine 2006; 5: 353–358.
Interventional Neuroradiology 21(2) 8. Marshman LA, David KM and Chawda SJ. Lumbar extradural arteriovenous malformation: Case report and literature review. Spine J 2007; 7: 374–379. 9. Patsalides A, Knopman J, Santillan A, et al. Endovascular treatment of spinal arteriovenous lesions: Beyond the dural fistula. Am J Neuroradiol 2011; 32: 798–808. 10. Willinsky R, Terbrugge K, Montanera W, et al. Spinal epidural arteriovenous fistulas: Arterial and venous approaches to embolization. Am J Neuroradiol 1993; 14: 812–817. 11. Geibprasert S, Pereira V, Krings T, et al. Dural arteriovenous shunts: A new classification of craniospinal epidural venous anatomical bases and clinical correlations. Stroke 2008; 39: 2783–2794. 12. Goodkin R and Laska LL. Vascular and visceral injuries associated with lumbar disc surgery: Medicolegal implications. Surg Neurol 1998; 49: 358–372. 13. Kawabori M, Hida K, Yano S, et al. Cervical epidural arteriovenous fistula with radiculopathy mimicking cervical spondylosis: Case report. Neuro Med Chir (Tokyo) 2009; 49: 108–113. 14. Khaldi A, Hacein-Bey L and Origitano TC. Spinal epidural arteriovenous fistula with late onset perimedullary venous hypertension after lumbar surgery: Case report and discussion of the pathophysiology. Spine (Phila Pa 1976) 2009; 34: E775–E779. 15. Kiyosue H, Tanoue S, Okahara M, et al. Spinal ventral epidural arteriovenous fistulas of the lumbar spine: Angioarchitecture and endovascular treatment. Neuroradiology 2013; 55: 327–336. 16. Uei H, Tokuhashi Y, Oshima M, et al. Vascular injury following microscopic lumbar discectomy treated with stent graft placement. Case report. J Neurosurg Spine 2014; 20: 67–70. 17. Lim SM and Choi IS. Spinal arteriovenous fistula: A unique pathway into the perimedullary vein. Interv Neuroradiol 2009; 15: 466–469. 18. Papadoulas S, Konstantinou D, Kourea HP, et al. Vascular injury complicating lumbar disc surgery. A systematic review: Review article. Eur J Vasc Endovasc Surg 2002; 24: 189–195. 19. Leonardo RC, Paul JH, Chandan K, et al. Spinal extradural arteriovenous fistulas: A clinical and radiological description of different types and their novel treatment with Onyx. J Neurosurg Spine 2011; 15: 541–549. 20. Pirouzmand F, Wallace MC and Willinsky R. Spinal epidural arteriovenous fistula with intramedullary reflux. J Neurosurg 1997; 87: 633–635. 21. Silva N Jr, Januel AC, Tall P, et al. Spinal epidural arteriovenous fistulas associated with progressive myelopathy. Report of four cases. J Neurosurg Spine 2007; 6: 552–558. 22. Lawton MT, Jacobowitz R and Spetzler RF. Redefined role of angiogenesis in the pathogenesis of dural arteriovenous malformations. J Neurosurg 1997; 87: 267–274. 23. Shin Y, Nakase H, Nakamura M, et al. Expression of angiogenic growth factor in the rat DAVF model. Neurol Res 2007; 29: 727–733. 24. Lanzino G, D’Urso PI, Kallmes DF, et al. Onyx embolization of extradural spinal arteriovenous malformations with intradural venous drainage. Neurosurgery 2012; 70: 329–333.
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VOLUME 21 - No. 2 APRIL 2015 ISSN 1591-0199 Online ISSN 2385-2011
neuroradiology solutions www.abmedica.it
Volume 21, No. 2, Pages 141 - 284, 2015
ab medica s.p.a.
Via nerviano, 31 - 20020 Lainate (MI) tel +39 02 933051 - fax +39 02 93305400 [email protected]
Journal of Peritherapeutic Neuroradiology, Surgical Procedures and Related Neurosciences Official Journal of: WFITN - World Federation of Interventional and Therapeutic Neuroradiology AAFITN - Asian & Australasian Federation of Interventional & Therapeutic Neuroradiology SAWITN - South American Working Group in Interventional and Therapeutic Neuroradiology The Chinese INR Coordinating Committee of the Chinese Doctor Association INSHCM - Interventional Neuroradiology Society of HCM City, Viet Nam Journal sponsored by JSNET - Japanese Society of Neuro Endovascular Therapy FIO - Italian Federation of Ozone Therapy Interventional Neuroradiology is published in cooperation with the American Journal of Neuroradiology
Case Report
Lumbar spinal epidural arteriovenous fistula with perimedullary venous drainage after endoscopic lumbar surgery
Interventional Neuroradiology 2015, Vol. 21(2) 249–254 ! The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1591019915583212 ine.sagepub.com
Toshiharu Murakami1, Ichiro Nakagawa1, Takeshi Wada2, Kimihiko Kichikawa2 and Hiroyuki Nakase1
Abstract Spinal epidural arteriovenous fistulas (AVFs) with perimedullary venous drainage are rare. This report describes a case of lumbar epidural AVF in a patient with a history of endoscopic lumbar discectomy at the same level 8 years prior to presenting with progressive myelopathy secondary to retrograde venous reflux into the perimedullary vein. A 69-year-old man presented with progressive lower extremity weakness and sensory disturbance and loss of sphincter control 8 years after endoscopic lumbar discectomy for a disc herniation at L4–5 level. Magnetic resonance imaging showed spinal cord edema and dilated intradural perimedullary vessels. Spinal angiography revealed an epidural AVF at the site of the previous endoscopic lumbar surgery with intradural perimedullary venous drainage. The fistula was successfully occluded via endovascular transarterial embolization, and the patient had stabilization of his neurological deficits. Lumbar spinal epidural AVFs, especially those associated with iatrogenic trauma, are rare. Endoscopic surgical procedure can occlude the epidural venous plexus and disturb venous drainage, thereby inducing local venous hypertension and leading to epidural AVF with perimedullary venous drainage. This type of pathology should be considered within the differential diagnosis of delayed neurological deterioration after spinal surgery.
Keywords Endoscopic lumbar surgery, epidural arteriovenous fistula, perimedullary venous drainage, transarterial embolization
Introduction Spinal epidural arteriovenous fistulas (AVFs) are rare among spinal vascular lesions.1–10 The precise mechanisms responsible for the development and growth of epidural and dural AVFs remain unclear; however, some reports suggest that there is a relationship between these entities and prior surgery or trauma.11–16 Spinal epidural AVFs are generally thought to present with benign clinical symptoms, such as radiculopathy. However, spinal epidural AVFs can cause acute paraplegia due to retrograde venous reflux into the medullary veins with venous congestion and consecutive intramedullary edema.17 The present report describes a case of a patient with a history of a lumbar disc herniation at L4–5 level who had undergone endoscopic lumbar discectomy 8 years prior. He presented with progressive myelopathy secondary to reflux into the perimedullary vein from an epidural AVF.
left L4/L5 lumbar vertebrae herniated intervertebral disk at another hospital 8 years earlier. He noted loss of strength of both lower limbs and sensory disturbance beginning 10 months prior to presentation to our department. Symptoms had gradually progressed to the point where he had difficulty walking and he had bladder dysfunction. On magnetic resonance (MR) imaging, high signal intensity was present in the lower portion of the spinal cord and serpentine perimedullary signal voids were shown in the T2-weighted image (Figure 1(a)). The images showed centromedullary edema below the mid-thoracic level as well as some minimally enlarged veins around the conus medullaris (Figure 1(b)). Sagittal and axial enhanced-computed tomography (CT) images showed a venous pouch in the posterior surface of the L4 vertebral body and showed dilated perimedullary veins (Figure 1(c, d).
1
Case report History and examination A 69-year-old man had previously undergone endoscopic herniated intervertebral disk enucleation for
Department of Neurosurgery, Nara Medical University, Nara, Japan Department of Radiology, Nara Medical University, Nara, Japan
2
Corresponding author: Ichiro Nakagawa, Department of Neurosurgery, Nara Medical University, 840 Shijo-cho, Kashihara City, Nara 634-8522, Japan. Email: [email protected]
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Interventional Neuroradiology 21(2)
Figure 1. Images from the patient upon admission. Sagittal T2-weighted MR image at the lumbar (a) and the lower thoracic (b) spine shows hyperintensity within the cord (arrowhead) and shows the presence of multiple flow voids on the surface of the cord (arrows). Sagittal (c) and axial (d) enhanced-CT shows a venous pouch in the posterior L4 vertebral body and shows dilated vessels (arrowhead). The AVF draining to the perimedullary vein (white arrow) at the L1 level through intradural vein (black arrow) (c).
Intra-arterial spinal angiography was performed. Angiography of the bilateral segmental L4 artery showed pathological opacification of the epidural venous space with very late reflux in an ascending intradural perimedullary vein. Selective angiography of the dorsal somatic branch of the right (Figure 2(a)) and left (Figure 2(b)) radicular artery at the level of L4 showed the AVF shunted to the epidural venous pouch and then drained through the intradural vein into the perimedullary vein at the level of L1 without epidural drainage. An epidural AVF was fed by the bilateral dorsal somatic branch of the fourth lumber segmental artery and the fistulas gathered to an epidural venous pouch draining into the perimedullary vein through an intradural vein located at cauda equina. No other feeding supply to the fistula was depicted on angiography. This case was regarded as spinal epidural AVF with
multiple shunt points around the venous pouch in the epidural venous plexus.
Treatment After discussion with the neurosurgical and endovascular teams, we planned endovascular transarterial embolization to eliminate the fistulas. The endovascular procedure was performed after obtaining written informed consent from the patient. Under local anesthesia, Marathon flow-directed microcatheters (Covidien, Dublin, Ireland) were introduced into the right dorsal somatic branch of the fourth lumber segmental artery as close as possible to the shunt points. The feeding arteries, venous pouch, and proximal portion of the draining veins were embolized with a mixture of n-butyl cyanoacrylate and lipiodol (Figure 2(c)).
Murakami et al.
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Figure 2. Selective angiography of the dorsal somatic branch (black arrows) of the right (a) and left (b) radicular artery at the level of L4 shows epidural AVFs with an epidural venous pouch (arrowhead) draining through the intradural vein into the perimedullary vein (white arrows). Transarterial embolization with NBCA was performed via the dorsal somatic branch of the right radicular artery (black arrow) (c). Complete obliteration of the fistula is seen after embolization (d).
Subsequently, transarterial embolization of the left dorsal somatic branch was performed in the same manner. The final angiogram revealed complete obliteration of the fistula (Figure 2(d)). Sagittal and axial CT after transarterial embolization showed a glue cast in the ventral epidural pouch (Figure 3(a, b)).
Postoperative course The patient’s neurological symptoms gradually improved, and his paresthesia of the lower extremities, gait disturbance, and urinary sphincter dysfunction resolved. By the 1-year follow-up time point, MR imaging revealed disappearance of the spinal cord swelling and the signal voids around the spinal cord (Figure 3(c)).
Discussion Spinal epidural AVFs, especially those associated with iatrogenic trauma, are rare, and only a few case reports have been published.11–16 We have summarized seven cases of spinal epidural AVFs with a history of the iatrogenic injury (including the present case) in Table 1. Most cases involved elderly males, were associated with perimedullary venous reflux causing congestive myelopathy, and were associated with the development of epidural AVFs a few months to a few years after surgery. The present case is the first report of lumbar epidural AVF in a patient with a history of endoscopic lumbar discectomy at the same level who presented with congestive myelopathy 8 years after surgery, although most
252
Interventional Neuroradiology 21(2)
Figure 3. Sagittal (a) and axial (b) CT after embolization shows glue cast in the ventral epidural pouch (arrowhead). Sagittal T2-weighted MR image showing disappearance of the spinal cord swelling and showing multiple flow voids on the spinal cord (c).
reported cases of epidural AVFs occurred after laminectomy surgery. Unlike spinal dural AVFs, epidural AVFs are located in the ventral epidural space, are fed by multiple epidural branches, and drain into the ventral epidural venous pouch. Further, they are generally thought to present with benign clinical symptoms, such as radiculopathy. Geibprasert et al. proposed a new classification of dural AVFs according to craniospinal epidural venous anatomy.11 Populations with ventral epidural AVFs had a female predominance, a benign clinical presentation, and a lower rate of spinal cord venous reflux when compared with that of patients with lateral epidural AVFs. However, some patients developed extensive thrombosis of the normal epidural outlets that leads to retrograde drainage to perimedullary veins as a variant of ventral epidural AVFs. The present case can be classified as ventral epidural AVF because of the shunt location, the perimedullary venous reflux without epidural drainage, and the presentation with congestive myelopathy. Kiyosue et al. clearly described the classification of spinal ventral epidural AVFs of the lumbar spine based on the drainage type.15 Dorsal somatic branches, which supply the vertebral body, were the primary feeding branches to the epidural AVFs, forming a shunted pouch that was located in the ventral epidural space. They described three types of venous drainage routes, perimedullary venous drainage (PM), paravertebral drainage (PV), and combined perimedullary and paravertebral venous drainage (PMPV). In PM-type AVFs, the epidural AVFs shunted to an epidural venous pouch and then drained through the radiculomedullary vein into the perimedullary vein. The PVtype AVFs drained via the radiculoemissary vein into the paravertebral veins. The present case can be classified as PM-type AVF because the AVF shunted to the
epidural venous pouch at the level of L4 and then drained through the paravertebral vein into the perimedullary vein at the level of L1 without epidural drainage. We assume that the complex venous flow into the perimedullary vein through the epidural venous pouch in the present case was due to previous endoscopic lumbar discectomy at this level that may have injured the epidural connective tissue involving the epidural veins, predisposing the patient to venous thrombosis and leading to formation of an AVF and complex retrograde venous drainage into the perimedullary vein, although it is difficult to exclude a possibility that the epidural AVF already existed and, following endoscopic discectomy, might have contributed to the change in behavior of the fistula. Postoperative neurologic deterioration after lumbar surgery can arise from a variety of causes, including residual disc fragments, large vessel injury, nerve root damage, and epidural hematomas.12,16,18 However, epidural fistulas causing a congestive myelopathy are very rare. Only four cases of epidural AVFs after laminectomy surgery have been published; only one case (the present case) after endoscopic lumbar discectomy has been reported (Table 1).14,17,19–21 The precise mechanisms responsible for the development and growth of epidural and dural AVFs remain unclear. However, venous hypertension and increased flow of blood into the low-resistance venous system can promote the growth of microscopic AVFs, which stimulates the release of angiogenic factors in experimental models.22,23 Lumbar decompression surgery, including endoscopic discectomy, could occlude the epidural venous plexus and disturb venous drainage, thereby inducing local venous hypertension and leading to epidural AVF. The mechanism related to the fistula formation would be essentially the same in both open surgical and endoscopic microdiscectomy, although
M
M
M
68
37
69
L4
L4-5
L3
T12
L3
L3
S1
Level
MED
Falling and laminectomy
T12 fracture Laminectomy (T11-L1) Prostatectomy
Laminectomy (L2/3,L3/4)
Laminectomy (L3/4)
Removal of AAA
Iatrogenic trauma
8 years
4 months
3 months
1 year
4 years, 8 months
2 years
4 years
Duration
Radiculopathy, bladder/ bowel incontinence Lower extremity weakness and paresthesia, loss of sphincter control
Myelopathy
Left lower extremity numbness Lower extremity painful paresthesia, gait disturbance Myelopathy
Leg weakness
Neurology
AAA: Abdominal aortic aneurysm; MED: micro-endoscopic discectomy; TAE: transarterial embolization; TVE: transvenous embolization.
F
M
65
60
M
68
Sliva N Jr. et al. (2007) Sliva N Jr. et al. (2007) Leonardo R et al. (2011) Present case
M
72
Pirouzmand F et al. (1997) Khaldi A et al. (2009) LIM SM et al. (2009)
Gender
Age (years)
Author (year)
Table 1. Reported cases of spinal epidural arteriovenous fistula with a history of an iatrogenic injury.
TAE TAE
Perimedullary vein
TVE 3
TAE
TAE
Surgery
TAE þ Surgery
Treatment
Epidural vein
Perimedullary vein
Perimedullary vein
Perimedullary vein
Perimedullary vein Paravertebral vein Perimedullary vein
Draining route
Good recovery
Good recovery
Lower limb deficit, Dysesthesia Good recovery
Good recovery
Good recovery
Good recovery
Outcome
Murakami et al. 253
254 endoscopic microdiscectomy is thought to be a less invasive treatment method. The therapeutic goal in the management of epidural AVFs is to obliterate the fistulous communication between the feeding artery and the draining vein by means of surgery or endovascular embolization. The majority of epidural AVFs with PM-type venous drainage can be successfully treated by transarterial embolization with either Onyx or glue,24 although transvenous embolization or surgical resection may also be possible.11,15 The patient in the present case was treated with transarterial embolization from the bilateral dorsal somatic branch using glue and obtained complete obliteration of the fistulas. Precise evaluation of the angioarchitecture of epidural AVFs enables successful endovascular embolization of the fistulas. This is the first description of lumbar epidural AVF in a patient with a history of endoscopic lumbar discectomy at the same level who presented with congestive myelopathy. Spinal epidural AVFs, especially those associated with iatrogenic trauma, are rare and difficult to diagnose. Although endoscopic lumbar surgery is thought to be a less invasive treatment method, lumbar epidural AVF should be considered after careful evaluation of images to improve clinical outcomes. Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Conflict of interest None declared.
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