Purpose We describe a case of subarachnoid haemorrhage caused by a high grade dural arteriovenous fistula (dAVF) with an identifiable venous rupture site on CT Angiography (CTA) in a patient with a remote history of recurrent severe dural sinus thrombosis requiring lifelong anticoagulation. The fistula was completely shut down by transarterial Onyx embolization with documented angiographic thrombosis of the downstream rupture site allowing restoration of her anticoagulation regimen. A completely independent, contralateral dAVF with isolated pial supply and cortical drainage was embolised electively. CTA has replaced conventional angiography as a first line vascular imaging study in cases of acute intracranial haemorrhage and if the imaging appearance is consistent with dAVF, a careful search should be made for a potential rupture site which may modify the treatment approach and objective.

Case report Case presentation: A 52-year-old right-handed female presented with sudden onset thunderclap headache, mild drowsiness. Her past medical history was significant for superior sagittal sinus and left transverse sinus venous thrombosis diagnosed in 2008 with repeat sinus venous thrombosis after discontinuing warfarin. Routine coagulopathy screening was negative and she was placed on lifelong warfarin for a presumed coagulopathy. At this presentation, her International Normalised Ratio (INR) was 3.6, which was rapidly reversed. Noncontrast CT brain demonstrated left sylvian subarachnoid haemorrhage and adjacent small discrete left temporal parenchymal haemorrhage. Subsequent CTA showed “arterialized” opacification of an ectatic left superficial middle cerebral vein harbouring a prominent saccular outpouching, with a narrow neck favoring pseudoaneurysm over varix. Conventional angiography confirmed a Cognard 2b dAVF centerd on the wall of a previously thrombosed and isolated left transverse sinus (TS) segment and draining via the left vein of Labbé and the sylvian vein with a patent pseudo aneurysm. The main arterial supply was from the left middle meningeal artery (MMA) but with contributions also from the left occipital artery, contra lateral MMA and occipital arteries as well as posterior and falx cerebelli meningeal supply arising from the left vertebral artery. A Marathon Micro Catheter (EV3 Irvine, CA) was advanced via the left MMA close to the fistulous network on the dural surface and a total of 4 ml of Onyx-34 (EV3, Irvine CA) was injected with complete penetration of the fistulous network and filling of the isolated fistulised segment of the left TS. A follow-up angiogram two months later showed no recurrent fistula. She subsequently underwent elective embolization and obliteration of the unruptured right orbitofrontal fistula. She will continue surveillance with time-resolved MR angiography (MRA) and time-of-flight (TOF) MRA.

Conclusion In the setting of dAVF and SAH, careful analysis of the emergent CTA may reveal the exact rupture site as represented by a pseudoaneurysm arising from an arterialised vein. The treatment goal should be to disconnect the arterializations of the ruptured vein but does not require casting of the rupture site itself.

Disclosures V. Daruwalla: None. B. Patel: None. A. Honarmand: None. S. Sherazi: None. S. Ansari: None. A. Shaibani: None. B. Bendock: None. M. Hurley: None.