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The Variable Presentations of Craniocervical and Cervical Dural Arteriovenous Malformations Robert Willinsky, M.D., Karel TerBrugge, M.D., Pierre Lasjaunias, M.D., Ph.D., and Walter Montanera, M.D. Department of Radiology, Toronto Western Hospital, Toronto, Canada, and Department of Radiology, H6pital Bicetre, Le Kremlin-Bicetre, France
Willinsky R, TerBrugge K, Lasjaunias P, Montanera W. The variable presentations of craniocervicaland cervicaldural arteriovenous malformations. Surg Neurol 1990;34:118-23. The authors reviewed four patients with dural arteriovenous malformations in the upper spinal axis. Two were at the foramen magnum and two were lower cervical. The patients presented with subarachnoid hemorrhage, a slowly progressive cervical myelopathy, a rapidly progressive thoracic myelopathy, and tinnitus with a sixth nerve palsy. This report emphasizes the importance of studying both the intracranial dural vessels as well as the supply to the cervical spine in searching for a spinal arteriovenous malformation. Subarachnoid hemorrhage with negative cerebral angiography requires spinal angiography if there are any signs or symptoms suggesting cord or nerve root dysfunction. Embolization by an endovascular approach resulted in an angiographic cure in two patients. A combination of embolization and surgery resulted in obliteration of the arteriovenous malformation in one patient. Embolization achieved a clinical cure in one patient, and clinical improvement in two patients. KEY wORDS: Dural arteriovenous malformation; Spine; Myelopathy; Subarachnoid hemorrhage; Endovascular embolization; Spinal angiography
Introduction Dural arteriovenous malformations (AVMs) of the spine now represent a well-defined entity since the studies of Kendall and Logue [8], Logue [9], and Merland et al [11]. The nidus o f the malformation is fed by radicular or dural arteries draining into the intradural coronal venous system. Most patients present in their fifth or sixth decades with a progressive lower limb weakness,
Address reprint requests to: Robert Willinsky, M.D.. Toronto Western Hospital,Department of Radiology,399 Bathurst Street, Toronto, Ontario, Canada M5T 2S8. Received December 4, 1989; accepted March 6, 1990.
© 1990by ElsevierSciencePublishingCo., Inc.
pain, and hypoesthesia in the legs, and diminished sphincter control. Tortuous filling defects on a myelogram usually suggest the diagnosis, which is confirmed by spinal angiography. It is now well accepted that a venous hypertension accounts for this progressive myelopathy [1]. Most of these dural AVMs are located in the thoracic and lumbar regions. This report reviews four patients with dural AVMs at the craniocervical and cervical regions. Dural arteriovenous malformations o f the spine are differentiated from intradural AVMs. Intradural AVMs are fed by the spinal cord circulation. Most are intramedullary, fed by both anterior and posterior spinal arteries. Uncommonly, the nidus is extramedullary on the surface of the cord [2]. These intradural, extramedullary malformations rarely are true fistula fed by a spinal cord artery [7]. These must be differentiated from dural AVMs fed by an intercostal artery, which also gives origin to an artery supplying the spinal cord [5].
Case Reports Case 1
A 57-year-old man had a 3-year history o f chest pain made worse by lying down or bending forward. H e then gradually developed numbness in both feet and legs. H e became constipated and had urinary hesitancy. On examination he had a sensory loss and decreased vibration sense in both feet. A myelogram showed an irregular block at T4 with possible enlarged veins on the cord. Following this myelogram, he developed urinary retention, back pain, and leg weakness. Examination showed 3/5 pyramidal leg weakness, 4 + reflexes in the legs, upgoing toes, and a T8 sensory level. A decompressive laminectomy ( T 2 - T 7 ) with durotomy showed a vascular malformation on the cord. Postoperatively, his leg strength became nil with a T4 sensory level to pinprick. Selective spinal angiography at thoracic, lumbar, and sacral levels showed stasis in the spinal cord circulation, but no malformation. Magnetic resonance imaging 0090-3019/90/$3.50
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(MRI) showed possible infarction in the thoracic cord with dilated veins on the surface of the cord. A repeat angiogram found a dural AVM (Figure 1) at the foramen magnum fed by the ascending pharyngeal artery. Embolization with N-butyl cyanoacrylate (NBCA) through the neuromeningeal branch of the ascending pharyngeal artery resulted in a short-lived, slight clinical improvement. Transiently, he developed loss of his gag reflex. A follow-up angiogram showed no residual supply from the external carotid, but filling of the fistula from the
Figure 1. Lateral ascending pharyngeal angiogram shows an arteriovenous fistula (curved arrow) at the foramen magnum draining inferiorly into posterior intradural coronal veins and superiorly into the posterior fossa (small arrowsj.
Figure 2. Anteroposterior right thyrocervical angtogram shows an arteriovenous fistula at the level of the right C8 root sleeve ( ~ j draining medially into the intradural coronal veins (short arrows) with a large venous pouch (open arrow).
vertebral. We were unsuccessful in attempting to block this vertebral supply by an endovascular approach. Five months later, this fistula no longer filled at angiography. Eighteen months later there has been no change in his clinical status.
Case 2 A 36-year-old man presented with a subarachnoid hemorrhage (SAH) with blood in the cisterna magna. This was associated with mild right arm and leg weakness. Cerebral angiography was negative. Seven months later he developed left arm pain and was treated with anticoagulants. He then developed a progressive quadriparesis over 2 to 3 days. He lost bladder and bowel function. A myelogram, computed tomography (CT) scan, and MRI suggested an intramedullary lesion of the cervical spinal cord. A laminectomy revealed an AVM on the cervical cord. An angiogram revealed a dural AVM on the C8 root on the right draining into the coronal veins on the cord (Figure 2). The feeding vessels from the right
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A
C
Figure 3. (A) Enhanced axial C T scan shows a lobulated extradural mass ~arrow) expanding the right C 4 - C 5 foramina. (B) Anteroposterior right vertebral angiogram shows a fistula (closed arrow) to the extradural vertebral venous plexus (open arrow). (C) Right thyrocervical angiogram shows a paravertebral arteriovenous malformation (closed arrow) draining into the extradural vertebral venous plexus (open arrows).
tive angiography showed that the malformation no longer filled. Over many months his strength has increased to the point where he is walking with a cane.
Case 3
costocervical and right vertebral arteries were embolized with NBCA. The patient slowly improved after the embolization, but 2 months later he deteriorated slightly. A repeat angiogram showed that the fistula remained open from the right vertebral. An anterior surgical approach failed to locate the fistula and necessitated ligation o f the proximal right vertebral. A follow-up angiogram showed the fistula still filled from retrograde flow down the right vertebral. A posterior surgical approach was used to clip the intradural draining vein. Postopera-
A 57-year-old man had a history of right arm numbness dating back 4 years. In the 4-year interval he developed a progressive weakness of his right arm and right leg. Urinary hesitancy developed. Plain cervical spine films showed erosion of the C 4 - C 5 foramina on the right. A CT scan showed an extradural mass at C 4 - C 5 (Figure 3 A). This was believed to be a tumor. An anterior cervical exploration revealed an AVM. Angiography showed a vertebral-to-vertebral fistula with a large extradural venous pouch (Figure 3 B). In addition, an extensive paravertebral AVM fed by right thyrocervical and costocervical branches was found (Figure 3 C). This AVM drained into the extradural vertebral venous plexus. Multiple embolizations were done over a 2-year period. A balloon occlusion of the vertebral-vertebral fistula was the first treatment. This resulted in a dramatic resolution of weakness in his right leg as well as disappearance o f the numbness in his right leg. His bladder
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ral lobe. Small branches from the right occipital artery participated in the supply to the malformation. The AVM was embolized through the ascending pharyngeal and occipital arteries with polyvinyl alcohol particles (150-250 /zm). His symptoms resolved. A follow-up angiogram 6 months later showed no AVM. Discussion
Figure 4. Lateral ascending pharyngel angiogram shows an A VM at the foramen magnum (curved arrow) draining suboccipitally and into the cavernous sinus (straight arrows). Note reflux into cortical veins (arrowhead).
function returned to normal. Subsequent embolizations of right costocervical and thyrocervical branches resulted in significant improvement of power in his right arm. He remained stable after these four embolizations for 1 year. Then he again developed some weakness in his right ankle and numbness in his right foot. Angiography showed the vertebral-vertebral fistula remained closed. However, collateral vessels from the right costocervical and right thyrocervical branches participated in the supply to the AVM. These were embolized with polyvinyl alcohol particles (150-250 /zm) with some improvement in symptoms. He continues to be closely monitored.
Case 4 A 50-year-old man had a 3-month history of a pulsatile tinnitus in the right ear and a right sixth nerve palsy. A CT scan showed a prominent right cavernous sinus and a dilated right superior ophthalmic vein. Angiography showed a small dural AVM at the foramen magnum fed by the right ascending pharyngeal artery (Figure 4). The AVM drains anteriorly into the right cavernous sinus and refluxes into the cortical veins over the tempo-
Most dural AVMs of the spine are located in the thoracic and lumbar regions. In the review by Rosenblum et al [13], 26 of 27 were in the low thoracic and lumbar areas, with one in the sacrum. In the series by Symon et al [14], of the 50 patients operated on, 47 were thoracic or lumbar, two were sacral, and one was at the foramen magnum. In the study by Merland et al [11], of the 13 patients, 12 were thoracolumbar and one was sacral. All patients in these three series presented with a progressive myelopathy that was often painful. In our four patients with cranial cervical dural AVMs, only one patient (case 1) had this classic presentation. The perimedullary coronal veins of the cord are in direct continuity with the veins of the posterior cranial fossa. Thus, a venous congestive myelopathy could occur secondary to a shunt at any level in the neural axis. When serpentine filling defects are seen on myelography in the face of a myelopathy, a spinal angiogram is required. After studying the intercostal branches to the thoracic and lumbar region, an AVM may not be demonstrated. Study of the sacral and cervical areas may still fail to demonstrate the shunt. If the symptoms have recently progressed, the diagnosis of Foix-Alajouanine syndrome may be considered (spontaneous thrombosis on the venous side). However, it is necessary to study the intracranial dural supply with selective internal and external studies. One of our patients (case 1) presented with a subacute thoracic myelopathy due to a fistula at the cranial cervical junction fed by the ascending pharyngeal artery. Wrobel et al [16] reported three similar patients with intracranial dural AVMs who presented with a myelopathy: there was a significant delay in the diagnosis in their three patients. In our patient there was a 2-week delay between the initial negative spinal angiogram and the follow-up angiogram that demonstrated the AVM. We repeated the angiogram to study the intracranial dural supply because there was stasis in the spinal cord circulation on the initial study. This confirmed the presence of a venous congestion, making it mandatory to search all possible locations for a shunt [15]. One of our patients (case 2) presented with a subarachnoid hemorrhage (SAH). There has been only one other report of an SAH in a dural AVM of the spine. Cahan et al [3] reported an SAH in a 19-year-old man with a high flow vertebral arteriovenous fistula at C5. In
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their report the patient's malformation was unusual in that he was young and the fistula drained into both intradural coronal veins and epidural veins. Subarachnoid hemorrhage does occur in the intradural intramedullary AVMs that typically present in the younger age group. This raises the question of how a patient with SAH and negative cerebral angiography should be managed. If there are any signs or symptoms referable to the spinal cord or nerve roots, then spinal angiography is indicated. The role of MRI of the spine in patients with SAH and negative cerebral angiography has yet to be clearly determined [4,10]. Dural AVMs at the cranial cervical junction can present with either intracranial or spinal symptoms. Two of our patients' AVMs were at this location. Case 4 presented with tinnitus and a sixth nerve palsy. Case 1 presented with a thoracic myelopathy. In both these patients the fistula was fed by the neuromeningeal branch of the ascending pharyngeal artery. It would be possible to miss these AVMs during cerebral angiography if selective internal carotid and distal external carotid injections were done. Therefore, selective injections of the ascending pharyngeal artery should be done. If this is not possible, common carotid injections would suffice. The treatment of dural AVMs of the spine is primarily endovascular [ 12]. Surgery remains important when embolization has failed or as an adjunct to embolization [14]. A permanent embolic agent such as NBCA is usually necessary, and it is imperative to reach the fistula itself and not just occlude the feeding artery. In case 2 we failed to eliminate the AVM by embolization because our embolic agent (NBCA) failed to block the actual fistula. This patient required surgery to achieve a complete obliteration of the AVM. In two patients an anglographic obliteration was obtained by embolization alone. Case 4 was cured with polyvinyl alcohol alone. However, the experience with polyvinyl alcohol in intracranial dural AVMs is discouraging due to the high recurrence rate [6]. In case 1 an angiographic obliteration was achieved with NBCA, although the complete resolution did not occur for 8 months. Case 3 proved to be extremely challenging to manage. The malformation consisted of a vertebral-vertebral fistula and a paravertebral AVM. The dilated extradural venous plexus produced a compressive myelopathy. Embolization had been carried out over four sessions. After each session there was significant symptomatic improvement followed by slight deterioration months later. Follow-up angiograms showed revascularization of the malformation through collateral flow. Unfortunately, much of the embolic material (NBCA) is deposited proximally in the feeding vessels. The balloon occlusion of the large vertebral-to-vertebral fistula achieved the most dramatic improvement. Good
Willinsky et al
penetration of the nidus or fistula with a permanent occlusive agent would be the goal of endovascular treatment. In summary, the diagnosis of dural AVMs of the spine often remains elusive. In three of our four patients the diagnosis was made at laminectomy. A cervical, craniocervical, or intracranial location must be considered. Subarachnoid hemorrhage with negative cerebral angiography should prompt the diagnosis if there are associated signs or symptoms referable to the spinal cord or cervical roots. Selective, high-quality angiograms of the entire cranial spinal axis must be done to make the diagnosis and to plan treatment strategy.
We would like to thank Dr. H. Smyth (Wellesley Hospital, Toronto), Dr. R. R. Hansebout (St.Joseph's Hospital, Hamilton), Dr. B. Schacter (Mount Sinai Hospital, Toronto), and Dr. Rowed (Sunnybrook Medical Center, Toronto) for referring these patients. We thank Dr. C. Wallace (Toronto Western Hospital) for his help in the management of these patients.
References 1. Aminoff MF, Barnard RO, Logue V. The pathophysiology of spinal vascular malformations. J Neurol Sci 1974;23: 255-63. 2. Aminoff MJ, Cutin PH, Norman D. Unusual type ofspinal arteriovenous malformation. Neurosurgery 1988;22:589-91. 3. Cahan LD, Higashida RT, Halbach VV, Hieshima GB. Variants of radiculomeningeal vascular malformations of the spine. J Neurosurg 1987;66:333-7. 4. Doppman JL, Di Chiro G, Dwyer AJ, Frank JL, Oldfield EH. Magnetic resonance imaging of spinal arteriovenous malformations. J Neurosurg 1987;66:830-4. 5. DoppmanJL, Di Chiro G, Oldfield EH. Origin of spinal arteriovenous malformation and normal cord vasculature from a common segmental artery: angiographic and therapeutic considerations. Radiology 1985;154:687-9. 6. Hall WA, Oldfield EH, Doppman JL. Recanalization of spinal arteriovenous malformations following embolization. J Neurosurg 1989;70:714-20. 7. Heros RC, Deburn GM, Ojemann RG, Lasjaunias PL, Naessens PJ. Direct spinal arteriovenous fistula: a new type of spinal AVM. Case report. J Neurosurg 1986;64:134-9. 8. Kendall BD, Logue V. Spinal epidural angiomatous malformationsdraining into intrathecal veins. Neuroradiology 1977; 13:181-9. 9. Logue V. Angiomas of the spinal cord: review of the pathogenesis, clinical features, and results of surgery. J Neurol Neurosurg Psychiatry 1979;42:1-11. 10. Masaryk TJ, Ross JS, Modic MT, Ruff RL, Sellman WR, Ratcheo son RA. Radiculomeningeal vascular malformations of the spine: MR imaging. Radiology 1987;164:845-9. 11. Merland JJ, Riche MD, Chiras J. Les Fistules Arterio-veineuses Intra-canalaires, Extra-medullaires A Drainage Veineux Medullaire. J Neuroradiol 1980;7:271-320. 12. Morgan MK, Marsh WR. Management of spinal dural arteriovenous malformations. J Neurosurg 1989;70:832-6.
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13. Rosenblum B, Oldfield EH, Doppman JL, Di Chiro G. Spinal arteriovenous malformations: a comparison of dural arteriovenous fistulas and intradural AVMs in 81 patients. J Neurosurg 1987;67:795-802. 14. Symon L, Kuyama H, Kendall B. Dural arteriovenous malformations of the spine. Clinical features and surgical results in 55 cases. J Neurosurg 1984;60:238-47.
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15. Willinsky R, Lasjaunias P, TerBru_gge K, Hurth M. Angiography in the investigation of spinal dural arteriovenous fistula. Neuroradiology (in press). 16. Wrobel CJ, Oldfield EH, Di Chiro G, Tarlov EC, Baker RA, Doppman JL. Myelopathy due to intracranial dural arteriovenous fistulas draining intrathecally into spinal medullary veins. Report of three cases. J Neurosurg 1988;69:934-9.
Surg Neurol 1990;34:118-23
The Variable Presentations of Craniocervical and Cervical Dural Arteriovenous Malformations Robert Willinsky, M.D., Karel TerBrugge, M.D., Pierre Lasjaunias, M.D., Ph.D., and Walter Montanera, M.D. Department of Radiology, Toronto Western Hospital, Toronto, Canada, and Department of Radiology, H6pital Bicetre, Le Kremlin-Bicetre, France
Willinsky R, TerBrugge K, Lasjaunias P, Montanera W. The variable presentations of craniocervicaland cervicaldural arteriovenous malformations. Surg Neurol 1990;34:118-23. The authors reviewed four patients with dural arteriovenous malformations in the upper spinal axis. Two were at the foramen magnum and two were lower cervical. The patients presented with subarachnoid hemorrhage, a slowly progressive cervical myelopathy, a rapidly progressive thoracic myelopathy, and tinnitus with a sixth nerve palsy. This report emphasizes the importance of studying both the intracranial dural vessels as well as the supply to the cervical spine in searching for a spinal arteriovenous malformation. Subarachnoid hemorrhage with negative cerebral angiography requires spinal angiography if there are any signs or symptoms suggesting cord or nerve root dysfunction. Embolization by an endovascular approach resulted in an angiographic cure in two patients. A combination of embolization and surgery resulted in obliteration of the arteriovenous malformation in one patient. Embolization achieved a clinical cure in one patient, and clinical improvement in two patients. KEY wORDS: Dural arteriovenous malformation; Spine; Myelopathy; Subarachnoid hemorrhage; Endovascular embolization; Spinal angiography
Introduction Dural arteriovenous malformations (AVMs) of the spine now represent a well-defined entity since the studies of Kendall and Logue [8], Logue [9], and Merland et al [11]. The nidus o f the malformation is fed by radicular or dural arteries draining into the intradural coronal venous system. Most patients present in their fifth or sixth decades with a progressive lower limb weakness,
Address reprint requests to: Robert Willinsky, M.D.. Toronto Western Hospital,Department of Radiology,399 Bathurst Street, Toronto, Ontario, Canada M5T 2S8. Received December 4, 1989; accepted March 6, 1990.
© 1990by ElsevierSciencePublishingCo., Inc.
pain, and hypoesthesia in the legs, and diminished sphincter control. Tortuous filling defects on a myelogram usually suggest the diagnosis, which is confirmed by spinal angiography. It is now well accepted that a venous hypertension accounts for this progressive myelopathy [1]. Most of these dural AVMs are located in the thoracic and lumbar regions. This report reviews four patients with dural AVMs at the craniocervical and cervical regions. Dural arteriovenous malformations o f the spine are differentiated from intradural AVMs. Intradural AVMs are fed by the spinal cord circulation. Most are intramedullary, fed by both anterior and posterior spinal arteries. Uncommonly, the nidus is extramedullary on the surface of the cord [2]. These intradural, extramedullary malformations rarely are true fistula fed by a spinal cord artery [7]. These must be differentiated from dural AVMs fed by an intercostal artery, which also gives origin to an artery supplying the spinal cord [5].
Case Reports Case 1
A 57-year-old man had a 3-year history o f chest pain made worse by lying down or bending forward. H e then gradually developed numbness in both feet and legs. H e became constipated and had urinary hesitancy. On examination he had a sensory loss and decreased vibration sense in both feet. A myelogram showed an irregular block at T4 with possible enlarged veins on the cord. Following this myelogram, he developed urinary retention, back pain, and leg weakness. Examination showed 3/5 pyramidal leg weakness, 4 + reflexes in the legs, upgoing toes, and a T8 sensory level. A decompressive laminectomy ( T 2 - T 7 ) with durotomy showed a vascular malformation on the cord. Postoperatively, his leg strength became nil with a T4 sensory level to pinprick. Selective spinal angiography at thoracic, lumbar, and sacral levels showed stasis in the spinal cord circulation, but no malformation. Magnetic resonance imaging 0090-3019/90/$3.50
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(MRI) showed possible infarction in the thoracic cord with dilated veins on the surface of the cord. A repeat angiogram found a dural AVM (Figure 1) at the foramen magnum fed by the ascending pharyngeal artery. Embolization with N-butyl cyanoacrylate (NBCA) through the neuromeningeal branch of the ascending pharyngeal artery resulted in a short-lived, slight clinical improvement. Transiently, he developed loss of his gag reflex. A follow-up angiogram showed no residual supply from the external carotid, but filling of the fistula from the
Figure 1. Lateral ascending pharyngeal angiogram shows an arteriovenous fistula (curved arrow) at the foramen magnum draining inferiorly into posterior intradural coronal veins and superiorly into the posterior fossa (small arrowsj.
Figure 2. Anteroposterior right thyrocervical angtogram shows an arteriovenous fistula at the level of the right C8 root sleeve ( ~ j draining medially into the intradural coronal veins (short arrows) with a large venous pouch (open arrow).
vertebral. We were unsuccessful in attempting to block this vertebral supply by an endovascular approach. Five months later, this fistula no longer filled at angiography. Eighteen months later there has been no change in his clinical status.
Case 2 A 36-year-old man presented with a subarachnoid hemorrhage (SAH) with blood in the cisterna magna. This was associated with mild right arm and leg weakness. Cerebral angiography was negative. Seven months later he developed left arm pain and was treated with anticoagulants. He then developed a progressive quadriparesis over 2 to 3 days. He lost bladder and bowel function. A myelogram, computed tomography (CT) scan, and MRI suggested an intramedullary lesion of the cervical spinal cord. A laminectomy revealed an AVM on the cervical cord. An angiogram revealed a dural AVM on the C8 root on the right draining into the coronal veins on the cord (Figure 2). The feeding vessels from the right
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A
C
Figure 3. (A) Enhanced axial C T scan shows a lobulated extradural mass ~arrow) expanding the right C 4 - C 5 foramina. (B) Anteroposterior right vertebral angiogram shows a fistula (closed arrow) to the extradural vertebral venous plexus (open arrow). (C) Right thyrocervical angiogram shows a paravertebral arteriovenous malformation (closed arrow) draining into the extradural vertebral venous plexus (open arrows).
tive angiography showed that the malformation no longer filled. Over many months his strength has increased to the point where he is walking with a cane.
Case 3
costocervical and right vertebral arteries were embolized with NBCA. The patient slowly improved after the embolization, but 2 months later he deteriorated slightly. A repeat angiogram showed that the fistula remained open from the right vertebral. An anterior surgical approach failed to locate the fistula and necessitated ligation o f the proximal right vertebral. A follow-up angiogram showed the fistula still filled from retrograde flow down the right vertebral. A posterior surgical approach was used to clip the intradural draining vein. Postopera-
A 57-year-old man had a history of right arm numbness dating back 4 years. In the 4-year interval he developed a progressive weakness of his right arm and right leg. Urinary hesitancy developed. Plain cervical spine films showed erosion of the C 4 - C 5 foramina on the right. A CT scan showed an extradural mass at C 4 - C 5 (Figure 3 A). This was believed to be a tumor. An anterior cervical exploration revealed an AVM. Angiography showed a vertebral-to-vertebral fistula with a large extradural venous pouch (Figure 3 B). In addition, an extensive paravertebral AVM fed by right thyrocervical and costocervical branches was found (Figure 3 C). This AVM drained into the extradural vertebral venous plexus. Multiple embolizations were done over a 2-year period. A balloon occlusion of the vertebral-vertebral fistula was the first treatment. This resulted in a dramatic resolution of weakness in his right leg as well as disappearance o f the numbness in his right leg. His bladder
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ral lobe. Small branches from the right occipital artery participated in the supply to the malformation. The AVM was embolized through the ascending pharyngeal and occipital arteries with polyvinyl alcohol particles (150-250 /zm). His symptoms resolved. A follow-up angiogram 6 months later showed no AVM. Discussion
Figure 4. Lateral ascending pharyngel angiogram shows an A VM at the foramen magnum (curved arrow) draining suboccipitally and into the cavernous sinus (straight arrows). Note reflux into cortical veins (arrowhead).
function returned to normal. Subsequent embolizations of right costocervical and thyrocervical branches resulted in significant improvement of power in his right arm. He remained stable after these four embolizations for 1 year. Then he again developed some weakness in his right ankle and numbness in his right foot. Angiography showed the vertebral-vertebral fistula remained closed. However, collateral vessels from the right costocervical and right thyrocervical branches participated in the supply to the AVM. These were embolized with polyvinyl alcohol particles (150-250 /zm) with some improvement in symptoms. He continues to be closely monitored.
Case 4 A 50-year-old man had a 3-month history of a pulsatile tinnitus in the right ear and a right sixth nerve palsy. A CT scan showed a prominent right cavernous sinus and a dilated right superior ophthalmic vein. Angiography showed a small dural AVM at the foramen magnum fed by the right ascending pharyngeal artery (Figure 4). The AVM drains anteriorly into the right cavernous sinus and refluxes into the cortical veins over the tempo-
Most dural AVMs of the spine are located in the thoracic and lumbar regions. In the review by Rosenblum et al [13], 26 of 27 were in the low thoracic and lumbar areas, with one in the sacrum. In the series by Symon et al [14], of the 50 patients operated on, 47 were thoracic or lumbar, two were sacral, and one was at the foramen magnum. In the study by Merland et al [11], of the 13 patients, 12 were thoracolumbar and one was sacral. All patients in these three series presented with a progressive myelopathy that was often painful. In our four patients with cranial cervical dural AVMs, only one patient (case 1) had this classic presentation. The perimedullary coronal veins of the cord are in direct continuity with the veins of the posterior cranial fossa. Thus, a venous congestive myelopathy could occur secondary to a shunt at any level in the neural axis. When serpentine filling defects are seen on myelography in the face of a myelopathy, a spinal angiogram is required. After studying the intercostal branches to the thoracic and lumbar region, an AVM may not be demonstrated. Study of the sacral and cervical areas may still fail to demonstrate the shunt. If the symptoms have recently progressed, the diagnosis of Foix-Alajouanine syndrome may be considered (spontaneous thrombosis on the venous side). However, it is necessary to study the intracranial dural supply with selective internal and external studies. One of our patients (case 1) presented with a subacute thoracic myelopathy due to a fistula at the cranial cervical junction fed by the ascending pharyngeal artery. Wrobel et al [16] reported three similar patients with intracranial dural AVMs who presented with a myelopathy: there was a significant delay in the diagnosis in their three patients. In our patient there was a 2-week delay between the initial negative spinal angiogram and the follow-up angiogram that demonstrated the AVM. We repeated the angiogram to study the intracranial dural supply because there was stasis in the spinal cord circulation on the initial study. This confirmed the presence of a venous congestion, making it mandatory to search all possible locations for a shunt [15]. One of our patients (case 2) presented with a subarachnoid hemorrhage (SAH). There has been only one other report of an SAH in a dural AVM of the spine. Cahan et al [3] reported an SAH in a 19-year-old man with a high flow vertebral arteriovenous fistula at C5. In
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their report the patient's malformation was unusual in that he was young and the fistula drained into both intradural coronal veins and epidural veins. Subarachnoid hemorrhage does occur in the intradural intramedullary AVMs that typically present in the younger age group. This raises the question of how a patient with SAH and negative cerebral angiography should be managed. If there are any signs or symptoms referable to the spinal cord or nerve roots, then spinal angiography is indicated. The role of MRI of the spine in patients with SAH and negative cerebral angiography has yet to be clearly determined [4,10]. Dural AVMs at the cranial cervical junction can present with either intracranial or spinal symptoms. Two of our patients' AVMs were at this location. Case 4 presented with tinnitus and a sixth nerve palsy. Case 1 presented with a thoracic myelopathy. In both these patients the fistula was fed by the neuromeningeal branch of the ascending pharyngeal artery. It would be possible to miss these AVMs during cerebral angiography if selective internal carotid and distal external carotid injections were done. Therefore, selective injections of the ascending pharyngeal artery should be done. If this is not possible, common carotid injections would suffice. The treatment of dural AVMs of the spine is primarily endovascular [ 12]. Surgery remains important when embolization has failed or as an adjunct to embolization [14]. A permanent embolic agent such as NBCA is usually necessary, and it is imperative to reach the fistula itself and not just occlude the feeding artery. In case 2 we failed to eliminate the AVM by embolization because our embolic agent (NBCA) failed to block the actual fistula. This patient required surgery to achieve a complete obliteration of the AVM. In two patients an anglographic obliteration was obtained by embolization alone. Case 4 was cured with polyvinyl alcohol alone. However, the experience with polyvinyl alcohol in intracranial dural AVMs is discouraging due to the high recurrence rate [6]. In case 1 an angiographic obliteration was achieved with NBCA, although the complete resolution did not occur for 8 months. Case 3 proved to be extremely challenging to manage. The malformation consisted of a vertebral-vertebral fistula and a paravertebral AVM. The dilated extradural venous plexus produced a compressive myelopathy. Embolization had been carried out over four sessions. After each session there was significant symptomatic improvement followed by slight deterioration months later. Follow-up angiograms showed revascularization of the malformation through collateral flow. Unfortunately, much of the embolic material (NBCA) is deposited proximally in the feeding vessels. The balloon occlusion of the large vertebral-to-vertebral fistula achieved the most dramatic improvement. Good
Willinsky et al
penetration of the nidus or fistula with a permanent occlusive agent would be the goal of endovascular treatment. In summary, the diagnosis of dural AVMs of the spine often remains elusive. In three of our four patients the diagnosis was made at laminectomy. A cervical, craniocervical, or intracranial location must be considered. Subarachnoid hemorrhage with negative cerebral angiography should prompt the diagnosis if there are associated signs or symptoms referable to the spinal cord or cervical roots. Selective, high-quality angiograms of the entire cranial spinal axis must be done to make the diagnosis and to plan treatment strategy.
We would like to thank Dr. H. Smyth (Wellesley Hospital, Toronto), Dr. R. R. Hansebout (St.Joseph's Hospital, Hamilton), Dr. B. Schacter (Mount Sinai Hospital, Toronto), and Dr. Rowed (Sunnybrook Medical Center, Toronto) for referring these patients. We thank Dr. C. Wallace (Toronto Western Hospital) for his help in the management of these patients.
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