No 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.

Intracranial dural arteriovenous fistulas (DAVFs) are rare lesions accounting for 10 to 15% of intracranial arteriovenous malformations. They involve an anomalous shunt between meningeal arteries, intracranial (venous sinuses and/or cortical veins), or medullary veins. The DAVFs are usually acquired, implying previous aggression of the dura mater. Thus, they are associated with dural sinus thrombosis, previous craniotomy, and trauma. However, they are idiopathic in most instances and have no evident cause. Their clinical presentation is variable, with symptoms depending on their location and venous drainage pattern. However, lesions with cortical venous drainage have the highest risk of causing the most significant morbidity and mortality. High clinical suspicion alongside noninvasive cross-sectional imaging techniques such as computed tomography and magnetic resonance imaging help establish the diagnosis. Digital subtraction angiography is the gold standard for diagnosis and accurate classification, permitting the evaluation of the feeding vessels, cortical venous drainage, and venous ectasia. Accordingly, a prompt diagnosis and precise classification of these lesions are essential. Endovascular treatment is nowadays the primary therapeutic modality for DAVFs. The access route can be divided into transarterial, transvenous, and combined approaches based on angioarchitecture, venous drainage model, and location. Surgical resection and stereotactic radiosurgery may be considered in some cases. A personalized case-by-case approach accomplishes a high complete treatment grade with a low complication rate. This review highlights the epidemiology, pathogenesis, clinical presentation, classification, diagnosis, and endovascular treatment of patients with intracranial DAVFs.