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.