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A DURAL CRANIOCERVICAL FISTULA IN A PATIENT WITH PROGRESSIVE CERVICAL MYELOPATHY S. Dekeyzer1, M. Lemmerling1, H. Fransen1, D. Dewilde1, L. Jans2, K. Verstraete2 A 47-year-old male patient with a dural craniocervical fistula is presented. One year after a car accident the man was admitted to the emergency department with severe nausea and progressive paralysis of the lower legs. MRI examination of the brain and cervical spine discovered cervical myelopathy and tortuous blood vessels anterior to the pons and cervical medulla. Angiography was performed to provide the final diagnosis of craniocervical fistula. An embolization of the fistula was performed, and all of the patient’s complaints disappeared within three days. Key-word: Fistula, dural.
Case report A 47-year-old male presented to the emergency department with progressive nausea and paralysis of the lower legs since a few days. His medical history mentioned bilateral frontal hemorrhagic brain contusions, after a car accident one year before. The actual MRI examination of the brain showed multiple residual parenchymal defects, resulting from the hemorrhagic contusions one year before, but additionally demonstrated a hyperintense signal in the pons and cervical medulla on the T2-weighted images, indicative for myelopathy (Fig. 1A). The contrast-enhanced MR images of the posterior fossa showed multiple tortuous enhancing vascular structures anterior to the pons and cervical medulla. An MRI examination of the cervical spine (Fig. 1B) demonstrated the same vascular tortuosity, and showed myelopathy extending to level C7. The findings were suggestive for the presence of a dural fistula, but the fistula itself could not be shown. No MRA of the spinal vessels was performed but a conventional angiographic procedure made clear that the right vertebral artery gave raise to a craniocervical arteriovenous variant (Fig. 1C). Two posterior meningeal branches originating from the left vertebral artery (Fig. 1D, E), ended in a dural fistula, draining towards the spinal perimedullary veins of the cervical spine. The fistula was classified as a type V dAVF (dural arteriovenous fistula), described in a revised classification of intracranial dural fistulas according to venous drainage (1).
A Fig. 1. — A. Sagittal T2-weighted MR images show enlarged cervical and perimedullary vessels (white arrows), as well as a hyperintense signal in the brain stem (black arrow). On the same images posttraumatic findings are noted in the frontal lobe (short black arrow), referring to the car accident one year before.
After embolization of these two branches, the dural fistula completely disappeared, and after three days the patient fully recovered from paralysis. Discussion Dural arteriovenous fistulas (dAVF) are rare. They are acquired and very often emerge after a cranial trauma, over months to years.
From: 1. Dpt of Radiology, AZ Sint-Lucas, Ghent, 2. Dpt of Radiology, UZ Ghent, Ghent, Belgium. Address for correspondence: Dr S. Dekeyzer, AZ Sint-Lucas, Dpt of Radiology, Groenebriel 1, B-9000 Ghent, Belgium. E-mail:
[email protected].
The pathogenesis of the dAVF is still unknown, but the neo-angiogenesis, caused by posttraumatic sinus thrombosis and venous hypertension is considered as the most likely theory (2, 3). They mostly occur in patients over 40 years of age, and are usually present on thoracic or lumbar level. To the contrary, this case is a craniocervical dAVF (4). Such fistula is an abnormal connection between an arterial feeder (or feeders), trough a dural fistula, and a perimedullary vein. A chronic spinal venous congestion develops and gives rise to venous congestion of the medulla, with often secondary ischemia and myelopathy. This leads
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B Fig. 1. — B. Sagittal T1-weighted MR images of the cervical spine, performed after intravenous injection of gadolinium, revealed the perimedullary veins as obviously enhancing tortuous structures anterior to the spine (arrows). The exact location of the fistula is not demonstrated. C. Selective conventional angiography of the left vertebral artery showed the craniocervical fistula (short arrow), and the progressively filling tortuous perimedullary veins (arrows).
D
C
E
Fig. 1. — D, E. Selective conventional angiography shows two posterior meningeal branches from the left vertebral artery, feeding the dural fistula (short arrow), with subsequent filling of the spinal perimedullary veins (arrows).
to symptoms as paralysis of the limbs, sensibility disturbance and bowel and bladder dysfunction (5). Dural fistulas are divided in different types and the present case is a craniocervical fistula type V, draining into a perimedullary spinal vein
instead of intracranial sinuses and veins (1, 6-8). The clinical and radiologic findings are similar with the much more frequent spinal dAVFs. On MR angiography of the brain or the spine, dural fistula can be suspected when dilated perimedullary
veins are seen on the surface of the cord and can be followed to the skull base (4). An increased medullar signal intensity on T2-weighted images is seen as a sign of medullopathy, and enhanced serpiginous structures anterior and posterior to the
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cord are noted on T1-weighted images after intravenous contrast administration. MR angiography often fails to show the dural fistula and its arterial feeders, since the arterial feeder of a spinal dural arteriovenous fistula is usually not dilated and the fistula itself can be very small. Therefore, the diagnosis is usually made by conventional angiography. Therapy for dAVFs must be individualized, requiring sometimes angiographic embolization and surgical resection (7). Embolization is the most non-invasive way to treat the fistula, as surgical ligation requires extensive exploration of the skull base, with inherent risks. For the same reason endovascular closure of the fistula was preferred in this case (4, 6). After angiographic closure of the fistula, clinical evolution is variable. Some patients may show remarkable improvement, whereas others remain
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unchanged, despite normalization of the MR imaging findings (6). Our patient fully recovered and was able to walk again within three days. The clinical control after two months showed an unchanged clinical status of the patient. References 1.
Cognard C., Gobin Y.P., Pierot L., Bailly A.L., Houdart E., Casasco A., Chiras J., Merland J.J.: Cerebral dural arteriovenous fistulas: clinical and angiographic correlation with a revised classification of venous drainage. Radiology, 1995, 194: 671-680. 2. Terada T., Higashida R.T., Halbach V.V., Dowd C.F., Tsuura M., Komai N., Wilson C.B., Hieshima G.B.: Development of acquired arteriovenous fistulas in rats due to venous hypertension. J Neurosurg, 1994, 80: 884-889. 3. Lawton M.T., Jacobowitz R., Spetzler R.F.: Redefined role of angiogenesis in the pathogenesis of dural arteriovenous malformations. J Neurosurg, 1997, 87: 267-274.
4. Mascalchi M., Scazzeri, F., Prosetti D., et al.: Dural arteriovenous fistula at the craniocervical junction with perimedullary venous drainage. AJNR, 1996, 17: 1137-1141. 5. Trop I., Roy D., Raymond J. Craniocervical dural fistula associated with cervical myelopathy: angiographic demonstration of normal venous drainage of the thoracolumbar cord does not rule out diagnosis. AJNR, 1998, 19: 583586. 6. van Rooij W.J., Sluzewski M., Beute G.N.: Intracranial dural fistulas with exclusive perimedullary drainage: the need for complete cerebral angiography for diagnosis and treatment planning. AJNR, 2007, 28: 348-351. 7. Hurst R.W., Bagley L.J., Scanlon M.: Dural arteriovenous fistulas of the craniocervical junction. Skull Base Surgery, 1999, 9: 1-7. 8. Sencer A., Kirilfi T.: Intracranial Dural Arteriovenous Fistulas: A brief review on classification and general features. Turkish Neurosurgery, 2006, 16: 57-64.
