Specific Imaging Findings

Dural arteriovenous fistula (DAVF) may not be visualized on routine CT or MRI images. MRI findings of larger or high-flow DAVFs include: multiple extra axial linear or tortuous flow-voids on T2WI, either at the base of the brain, around the tentorial incisura, in the basal cisterns, or in the sulci along the convexity, which are even better visualized with susceptibility-weighted imaging (SWI). Major deep and superficial draining veins may be enlarged. Large tortuous signal voids may be present in the scalp of the affected side. Post-contrast images may show prominent tortuous vessels within the sulci indicating retrograde cortical venous drainage. Large deep medullary (white matter) veins and white matter T2 hyperintensity are indicative of venous hypertension. Perfusion studies show increased relative cerebral blood volume (rCBV) in all of these patients. CT demonstrates complications, primarily subarachnoid, subdural, parenchymal, or occasionally intraventricular hemorrhages. MRA or CTA in the high-flow DAVF often show enlarged tortuous arterial and venous structures. Findings of high intensity structures adjacent to the sinus wall on 3D TOF MRA appear to be diagnostic of DAVF. MRV confirms enlarged venous structures and may show evidence of venous sinus thrombosis or occlusion. DSA demonstrates the exact fistula site, is very useful for treatment planning and offers endovascular treatment options.

Pertinent Clinical Information

DAVFS occur in adults, more commonly females. They may be clinically silent and incidentally found at imaging. Pulsatile tinnitus, audible bruit, headache, cognitive impairment, seizures, cranial nerve palsies and focal neurologic deficit may all occur in patients with DAVF. Lesions located in the cavernous sinus region present with ophthalmoplegia, eye pain, orbital congestion or features of carotid cavernous fistula. Development of venous hypertension frequently leads to progressive dementia. Acute symptoms may be due to intracranial hemorrhages, which occur in DAVFs with retrograde cortical flow. Therefore, the presence of retrograde cortical flow represents a clear indication for treatment of these lesions.