Dural Arteriovenous Fistula

59yo male with pulsatile tinnitus, progressive dementia, hypobulia, Parkinsonism and right hemiparesis developing over 10 years, worsening in the preceding 3 months. Physical examination revealed a pulse-synchronous bruit over his posterior scalp and left postauricular region, and bilateral papilloedema. MRI (not shown) demonstrated restricted diffusion in the basal ganglia and multiple distended cortical veins over both hemispheres and in the posterior fossa suggestive of a high-flow arteriovenous shunt. Selective angiography, left external carotid artery shows typical features of a dural arteriovenous fistula of the transverse sinus, with multiple distended branches of the occipital, posterior auricular, ascending pharyngeal and middle meningeal arteries connecting directly to the mid-transverse sinus. Note retrograde opacification of the superior sagittal sinus and left vein of Labbe.

Dural arteriovenous fistula is an uncommon but treatable cause of dementia, but can manifest clinically in a myriad of ways, the most common of which include pulsatile tinnitus, intracerebral haemorrhage (parenchymal, subarachnoid or subdural), dementia, focal neurological deficit, visual disturbance, headache and seizure. The condition is acquired, and is thought to result from aberrant recanalisation of a previously thrombosed dural sinus (not unlike cavernous transformation of the portal vein following previous thrombosis). The prevalence of the disease is estimated at between 2 and 4 per 1,000,000 in the Western Hemisphere. The commonest locations include the torcular/transverse sinus/sigmoid sinus region, the cavernous sinus (where it is inaccurately referred to as indirect or “low-flow” caroticocavernous fistula), the cribriform plate region, the tentorial hiatus and, less commonly, over the cerebral hemispheres or around foramen magnum.

The most important feature to recognise in the diagnosis of DAVF is the presence or absence of retrograde flow into cortical veins (retrograde leptomeningeal venous drainage), because this indicates a significant risk of haemorrhage ranging from 5-40%, depending on the type and location of the shunt.

This patient was treated with embolisation in two stages and, by 2 months post-treatment, had returned to his premorbid status with only very mild impairment of short term memory.

Credit: Dr Jason Wenderoth