Transverse and Sigmoid Dural Arteriovenous Fistula

Johnny Wong, Rachel Tymianski, Vitor Mendes Pereira, Ivan Radovanovic, and Michael Tymianski

Abstract

Dural arteriovenous fistulae (DAVFs) are arteriovenous shunts located within the dural leaflets and constitute 10 to 15 % of intracranial vascular malformations. Transverse and sigmoid DAVFs are the most common locations for DAVF. Clinical presentations include pulsatile tinnitus, intracranial hemorrhage, and neurological deficits. Currently, both Borden and the Cognard classifications of DAVF have gained widespread popularity, and are based on patterns of venous drainage from the dural fistulae. Low-risk DAVFs (Borden I or Cognard I, IIa) have no retrograde leptomeningeal venous drainage and are associated with a relatively benign natural history. ¹^, ² In contrast, DAVF with retrograde leptomeningeal venous drainage (Borden II, III or Cognard IIb, III, IV) are associated with an increased risk of hemorrhage and neurological deficits. Treatment is therefore recommended for high risk DAVF, and its objective is to completely obliterate the arterialized draining vein. Available modalities include microsurgery, endovascular embolization (via transarterial or transvenous approaches), or radiosurgery. This chapter outlines the natural history of DAVF, and the indications and surgical techniques for treatment of transverse and sigmoid DAVF.

Keywords: dural arteriovenous fistula, transverse sinus, sigmoid sinus, microsurgery, leptomeningeal venous drainage

32.1 Introduction

Dural arteriovenous fistulae (DAVF) represent approximately 10 to 15% of all intracranial arteriovenous malformations. ³ The etiology of DAVF is not well understood, but associations with head trauma, dural sinus thrombosis, tumors, infections, or previous craniotomies have been identified. ²^, ⁴^, ⁵ Unlike brain arteriovenous malformations, DAVF are generally thought to be acquired lesions ⁵^, ⁶ and are associated with an annual hemorrhage risk of 1.5%. ⁶

Common locations for DAVF include transverse-sigmoid sinus (40–50% of cases), cavernous sinus (16–20%), superior sagittal sinus (8–13%), tentorium (4–12%), and anterior skull base (4%). ¹^, ⁶^, ⁷

DAVF are characterized by dural arterial supply, either via single or multiple arterial feeders usually to a common fistulous point of drainage into a venous sinus or leptomeningeal veins. ⁸ In DAVF involving the transverse and sigmoid sinus, the arterial supply is mainly derived from branches of the external carotid artery, such as intraosseous branches of occipital artery, posterior auricular artery, middle meningeal artery, and ascending pharyngeal artery. Other sources of arterial supply include meningeal branches from the vertebral artery and the tentorial branch of the meningohypophyseal trunk (artery of Bernasconi–Cassinari) from the internal carotid artery. Venous drainage may be through ipsilateral transverse and sigmoid sinuses or through the contralateral side if the ipsilateral sinus is occluded. Cortical draining veins may be involved when arterialized blood flows in a retrograde direction through leptomeningeal veins, resulting in venous hypertension, congestion, and hemorrhage. ⁸

32.2 Classification, Presentation, and Natural History

The most popular classifications of DAVF are those of Cognard et al, ¹ and Borden et al ( ▶ Table 32.1). ² The Cognard classification has five categories based on the following angiographic features: Involvement and direction of flow through venous sinuses, presence of retrograde leptomeningeal venous drainage (or cortical venous reflux), venous ectasia/pouches or drainage into spinal veins. ¹ The Borden classification is a simpler system: type I has dural venous sinus drainage only ( ▶ Fig. 32.1a, ▶ Fig. 32.2a), type II contains both sinus and retrograde leptomeningeal venous drainage ( ▶ Fig. 32.1b, ▶ Fig. 32.3a), while in type III, drainage occurs through retrograde leptomeningeal venous drainage without sinus involvement ( ▶ Fig. 32.1c, ▶ Fig. 32.4b). ²

**Table 32.1** Radiological and clinical features of DAVF according to Borden and Cognard classifications
Classification		Radiological features		Clinical features
Borden ²	Cognard ¹	Sinus Involvement	Cortical Venous Reflux	Clinical Presentation
I	I	Anterograde	No	Pulsatile tinnitus; 2% present as hemorrhage or neurological deficit Annual hemorrhage risk: 2%
I	IIa	Retrograde	No
II	IIb	Retrograde	Yes	39% present as hemorrhage or neurological deficit Annual hemorrhage risk: 8.1%
III	III	None	Yes	79% present as hemorrhage or neurological deficit Annual hemorrhage risk: 8.1%
III	IV	None	Yes, with venous ectasia
	V		Spinal venous drainage	Progressive myelopathy in 50%

Fig. 32.1 Transverse-sigmoid junction DAVF with middle meningeal artery supply. (a) Borden type I with anterograde flow in sigmoid sinus. (b) Borden type II with occlusion of sigmoid and superior petrosal sinuses, retrograde flow into transverse sinus and cortical venous reflux. (c) Borden type III with cortical venous reflux plus ectasia and no sinus involvement.

Fig. 32.2 (a) External carotid arteriogram of Borden type I transverse sinus DAVF. (b) Transarterial embolization with Onyx and transvenous embolization with coils.

Fig. 32.3 (a) External carotid arteriogram of Borden type II DAVF with cortical venous reflux. (b) Angiogram following transarterial embolization with Onyx.

Fig. 32.4 (a) Axial T1-weighted MRI with gadolinium of Borden type III DAVF with contrast enhancement and prominent blood vessels. (b) Preoperative lateral (left) and anteroposterior (right) external carotid arteriogram with transosseous supply from left occipital artery and venous reflux into superior vermian vein. (c) and (d) Intraoperative photo and ICG angiogram of “red” arterialized vein and venous pouch before disconnection of cortical venous reflux.

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