Acquired pial arteriovenous fistula secondary to cerebral cortical vein thrombosis: A case report and review of the literature

Abstract

Pial arteriovenous fistulas (AVFs) are rare neurovascular malformations. They differ from arteriovenous malformations (AVMs) in that they involve single or multiple feeding arteries, draining directly into a dilated cortical vein with no intervening nidus. Pial and dural AVFs differ in blood supply, as the first originate from pial or cortical arteries and the latter from outside the dural leaflets. Unlike dural AVFs, most of the pial AVFs are supratentorial. The vast majority are congenital, manifesting during infancy. Acquired pial AVFs are significantly rarer and occur after vasculopathy, head trauma, brain surgery, or cerebral vein thrombosis. We describe a unique case of an acquired pial AVF in a 50-year-old man secondary to a cortical vein thrombosis manifesting as a focal-onset seizure with secondary generalization. A cerebral digital subtraction angiography revealed a low-flow pial AVF fed by a postcentral branch of the left middle cerebral artery draining to the superior sagittal sinus via a cortical vein. It also showed a collateral venous circulation adjacent to the previously thrombosed left parietal vein. There was no evidence of an associated dural AVF or venous varix. Endovascular treatment was scheduled three months later, but the angiogram preceding the embolization showed spontaneous and complete closure of the malformation. To our knowledge, this is the first case illustrating acquired pure pial AVF unaccompanied by a dural component following cortical vein thrombosis, eventually resulting in an unprompted closure.

Keywords: Pial arteriovenous fistula; cortical vein thrombosis; digital subtracted angiography; endovascular treatment.; magnetic resonance imaging.

Figure 1.

Initial brain magnetic resonance imaging. (a) and (b) Axial T2* and T1 weighted images, respectively, showing an enlarged left parietal cortical vein presenting high T1 and low T2* signals relevant to a cortical vein thrombosis (arrows). (c) and (d) Axial fluid attenuated inversion recovery (FLAIR) and diffusion-weighted images, respectively, showing a hyperintensity FLAIR signal area in the left parietal convexity region associated with restricted diffusion consistent with venous infarct (star).

Figure 2.

Follow-up brain magnetic resonance imaging. (a) Axial T2 weighted image and (b) 3D T1 axial reformat image with maximal intensity projection reconstruction showing multiple dilated vascular structures in the left frontoparietal convexity (black arrows). (c) 3D T1 axial reformat image demonstrating the revascularization of the previously thrombosed left parietal cortical vein (white arrow). (d) Axial fluid attenuated inversion recovery image displaying a hyperintensity area of the left parietal region consistent with the venous infarct’s sequelae (arrowhead).

Figure 3.

Initial cerebral digital subtraction angiography of the left internal carotid artery. Lateral (a) and oblique (b) views during the early arterial phase showing an early opacification of a parietal cortical vein (arrowheads) fed directly by a small parietal branch of the left middle cerebral artery (arrow) consistent with pial arteriovenous fistula. (c) Lateral view during the venous phase demonstrating a left parietal collateral venous circulation adjacent to the previously thrombosed cortical vein.

Figure 4.

Follow-up cerebral digital subtraction angiography of the left internal carotid artery. Lateral (a) and oblique (b) views during the early arterial phase showing the exclusion of the pial arteriovenous fistula. (c) Lateral view during the venous phase demonstrating a substantial decrease of the left parietal collateral venous circulation.