Challenges of dural arteriovenous fistulas

The authors provide a case report and review of dural arteriovenous fistulas (DAVFs) and their unique diagnostic and therapeutic challenges. They describe the “papilledema” shunt of DAVFs, which shunt blood into the transverse or superior sagittal venous sinuses raising intracranial pressure and thus causing papilledema.

They caution that the imaging features of a DAVF that cause papilledema may be subtle. If not detected on noninvasive neuroimaging and if lumbar puncture is performed, there is a substantial risk of brain herniation. Digital subtraction catheter angiography is necessary to definitively diagnose and treat the disorder.

They explain that three types of DAVFs have predominantly ophthalmic manifestations:

• The “red eye” shunt, a fistula located in or near the cavernous sinus that drains primarily into the orbit, can cause reduced visual acuity due to retinal venous stasis or steal from optic nerve circulation, elevated IOP, periocular pain, ptosis, and ophthalmoplegia largely due to orbital and ocular venous congestion.
• The “white eye” shunt, a fistula also located in or near the cavernous sinus but draining posteriorly into the petrosal and pterygoid venous sinuses, presents usually without any features of orbital venous congestion but with reduced visual acuity due largely to vascular steal from the intracranial optic nerve and ophthalmoplegia owing to vascular steal from vasa nervorum of ocular motor cranial nerves.
• The “papilledema” shunt, a fistula located in the sagittal, transverse or sigmoid sinus. “Arterialization” of these major draining sinuses raises venous and intracranial pressure.

They reviewed the case of a 35-year-old woman who presented with papilledema. Noninvasive brain vascular imaging showed signs of a DAVF. Digital angiography delineated the DAVF and revealed cortical venous reflux. After three transarterial embolizations with ethylene vinyl alcohol, the DAVF was closed and papilledema resolved.

They say that cortical venous reflux, which may be relatively common in these DAVFs, impels the need for endovascular closure. The transvenous route, often employed for closing cavernous sinus DAVFs, should be avoided because of the dangers of dural venous sinus thrombosis.