SPINAL DURAL ARTERIOVENOUS FISTULAE: MR IMAGING CHARACTERISTICS AND CLINICAL SIGNIFICANCE PATRICK DO, MD JEFFREY DORR, MD PRIYA KRISHNARAO, MD MAHESH PATEL, MD SANTA CLARA VALLEY MEDICAL CENTER

DISCLOSURE STATEMENT The authors have no actual or potential conflict of interest in relation to this presentation

GOALS AND OBJECTIVES Review the clinical and epidemiologic features of spinal dural arteriovenous fistulae (SDAVFs) Demonstrate and discuss MR imaging findings Discuss therapeutic options of SDAVFs

BACKGROUND SDAVFs are a rare and often underdiagnosed entity... yet they represent the most common spinal vascular malformation and have quite important clinical significance

PATHOPHYSIOLOGY feeding radiculomedullary artery enters dura mater and forms a fistula with a medullary vein 2 … thus arterializing the corona venous plexus … causing chronic venous hypertension … leading to chronic medullary ischemia

EPIDEMIOLOGY Male 6th decade of life 60% occur spontaneously, 40% are related to trauma

CLINICAL FINDINGS Non-specific symptomatology lower extremity paresthesias sensory loss radicular pain, progressing superiorly Clinical diagnosis is difficult and can be confounded with degenerative disease or neoplasm

MR IMAGING FINDINGS serpentine flow voids on the dorsal spinal cord surface cord enlargement intramedullary T2-hyperintensity = cord edema peripheral T2 hypointensity = dilated pial capillaries, secondary to venous hypertension cord enhancement

MR IMAGING: T2-WEIGHTED intramedullary T2 hyperintensity perimedullary flow voids

MR IMAGING: T2-WEIGHTED intramedullary T2 hyperintensity perimedullary flow voids

CATHETER ANGIOGRAPHY Digital subtraction angiography (DSA) during contrast injection of a segmental artery demonstrates spinal dural arteriovenous fistula

ASSOCIATED CONDITIONS Subacute necrotizing myelopathy can be associated i.e. Foix-Alajouanine syndrome chronic venous hypertension leading to chronic medullary ischemia fusiform cord swelling with peripheral enhancement non-specific T1 and T2 lengthening

THERAPEUTIC OPTIONS Goal: occlude the “shunting zone” (the most distal part of the artery and the most proximal part of the draining vein) Options: 1. Endovascular occlusion of the feeding radiculomeningeal artery and proximal draining vein 2. Surgical occlusion of the intradural vein (often performed if endovascular treatment fails)

ENDOVASCULAR THERAPY superselective catheterization of the feeding radiculomeningeal artery occlusion with liquid embolic agent, e.g. n-butyl 2- cyanoacrylate with lipiodol ~25% success rate 1

SURGICAL THERAPY (hemi)laminectomy at the level of the fistula intradural division of the shunting vein to the perimedullary coronal venous plexus given that myelopathy is caused by arterialization of the normal venous plexus minimal reported complications or side effects

CONCLUSION Spinal dural arteriovenous fistulas have non-specific clinical symptoms Imaging evaluation, particularly MRI, is essential for making the diagnosis Endovascular occlusion is less invasive but often unsuccessful; surgical occlusion is definitive

REFERENCES 1. van Dijk JMC, TerBrugge KG, Willinsky RA, Farb RI, Wallace MC. Multidisciplinary Management of Spinal Dural Arteriovenous Fistulas. Stroke 2002; 33: Aminoff M, Logue V. The prognosis of patients with spinal vascular malformations. Brain 1974; 97: Gilbertson JR, Miller GM, Goldman MS, Marsh WR. Spinal Dural Arteriovenous Fistulas: MR and Myelographic Findings. Am J Neuroradiol 1995; 16: Krings T, Geibprasert S. Spinal Dural Arteriovenous Fistulas [Review Article]. Am J Neuroradiol 2009; 30: