Type 1 Vascular Malformation (Dural Arteriovenous Fistula)

KEY FACTS

Terminology

• Synonyms: Type 1 spinal arteriovenous fistula (AVF), dural AVF, dural fistula

• Spinal arteriovenous (AV) fistula, present within dura, with intradural distended draining veins

Imaging

• Cord enlarged, T2WI hyperintense, vessel flow voids on cord surface

• Multiple enhancing serpentine veins on cord surface

• Dynamic contrast-enhanced MRA capable of defining dilated intradural veins; very useful to guide catheter angiography

• Spinal catheter arteriography is gold standard for confirming diagnosis/treatment

Top Differential Diagnoses

• CSF pulsatile flow artifact

• Spinal cord tumor

• Spinal cord arteriovenous malformation

• Tortuous “redundant” roots from spinal stenosis

• Collateral venous flow

Pathology

• Venous hypertension from engorgement reduces intramedullary AV pressure gradient, causing reduced tissue perfusion and cord ischemia

Clinical Issues

• Most common presentation is progressive lower extremity weakness with both upper + lower motor neuron involvement

• Very rarely presents with subarachnoid hemorrhage

• Middle-aged male with progressive lower extremity weakness exacerbated by exercise

• Persistent edema and enhancement of cord can occur even with successful clinical treatment of fistula

• Treatment: Endovascular fistula occlusion with permanent embolic agents; surgical fistula obliteration

TERMINOLOGY