SPINAL DURAL ARTERIOVENOUS FISTULAE: MR IMAGING CHARACTERISTICS AND CLINICAL SIGNIFICANCE PATRICK...
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Transcript of SPINAL DURAL ARTERIOVENOUS FISTULAE: MR IMAGING CHARACTERISTICS AND CLINICAL SIGNIFICANCE PATRICK...
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 vein2
• … 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 ANGIOGRAPHYDigital 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 rate1
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: 1578-1583.
2. Aminoff M, Logue V. The prognosis of patients with spinal vascular malformations. Brain 1974; 97: 211-218.
3. Gilbertson JR, Miller GM, Goldman MS, Marsh WR. Spinal Dural Arteriovenous Fistulas: MR and Myelographic Findings. Am J Neuroradiol 1995; 16: 2049-2057.
4. Krings T, Geibprasert S. Spinal Dural Arteriovenous Fistulas [Review Article]. Am J Neuroradiol 2009; 30: 639-648.