Mechanism of the Formation of Dural Arteriovenous Fistula — The Role of the Emissary Vein

Abstract

<jats:p> Dural arteriovenous fistula (DAVF) can be separated into two types: DAVF which drains through an affected sinus (sinus type) and DAVF with direct reflux to the cortical vein (non-sinus type). The present report attempted to clarify the mechanism of formation and development of DAVF focusing on the emissary vein (EV) hypothesis. </jats:p><jats:p> First, inflammation occurs at the penetrating point of the EV on the dura due to idiopathic or secondary causes. Local inflammatory reactions induce vessel dilatation and neovascularization, and subsequently create arteriovenous (AV) connections on the arteriole level. Although EV communicating with dural arteries might play a role as draining routes at first, they start to degrade due to compression of enlarged emissary arteries or to a hemodynamic shift to the drainage pathway of least resistance. Following the occlusion of drainage pathway through EV into the sinus or cortical veins may form, resulting in clinically detectable DAVF. The AV shunt then expands to the surrounding dura associated with recruitment of feeders from distant sites induced by expression of angiogenetic factors and a shift in the hemodynamic balance. In sinus type DAVF, the sinus is progressively compartmentalized and finally occludes due to thrombogenesis with activated coagulopathy or to hemodynamic hypertrophy of the sinus wall. This progression results in the mature, aggressive DAVF with drainage impairments. Previous mechanistic hypotheses focusing on sinus hypertension and sinus thromboses cannot explain the pathogenesis of non-sinus type of DAVF. Although the etiology of DAVF may be concerned by the thrombo-occlusive change of sinus, the unique theory presented in this report may enable an understanding of the common etiology of both types of DAVF. </jats:p>

Recurrence of “cured” dural arteriovenous fistulas after Onyx embolization

“…33 Additional theories have centered on the promotion of dural neovascularization by angiogenic factors. The release of angiogenic growth factors such as vascular endothelial growth factor and basic fibroblast growth factor may occur in response to hypoxia or increased venous pressure.…”

A Unique Type of Dural Arteriovenous Fistula at Confluence of Sinuses Treated with Endovascular Embolization: A Case Report

“…DAVF in adulthood is usually considered to be an acquired and progressive disease [3] and there is no relationship to the hereditary or developmental disorders. But there are a few case reports of DAVF in neonates and childhood which indicate a congenital origin [4, 5].…”

Spinal dural arteriovenous fistula associated with L-4 isthmic spondylolisthesis

“…sive lesions, 9,14 most cases are reportedly idiopathic and are independent of the preceding hematological and immunological impairments. 7 However, some pathophysiological mechanisms, such as inflammation, infection, trauma, and thrombosis, are well illustrated as a cause of intracranial DAVFs, which have been more thoroughly studied in previous reports. 1,7,16,17 Several cases of spinal DAVFs have been reported to be secondary to other pathologies (Table 1).…”

“…3 Third, in most cases of spinal DAVFs, inflammation is assumed to develop undetected or as an autoimmune reaction. 7 Local inflammation may expand with expression of various cytokines, cause vessel dilation, and open the physiological arteriovenous shunt. 7 This could lead to activation of physiological arteriovenous shunting, resulting in newly formed spinal DAVFs.…”

“…7 Local inflammation may expand with expression of various cytokines, cause vessel dilation, and open the physiological arteriovenous shunt. 7 This could lead to activation of physiological arteriovenous shunting, resulting in newly formed spinal DAVFs. Based on these facts, we hypothesize that, in the present case, the abnormal vascular communication developed secondary to the inflammation triggered by microtrauma from isthmic spondylolisthesis.…”