**7. Vein of Galen malformations**

Vein of Galen malformations are extremely rare lesions occurring in one out of a million live births [57]. They are treated almost exclusively with endovascular surgery. The lesions are amenable to endovascular embolization in the newborn presenting with heart failure or diagnosed in utero. An initial treatment stage is necessary and followed by additional staged embolization when the child is large enough to undergo more extensive embolization. Embolization strategies include closing the individual arteriovenous shunts or the initial venous side of the malformation.

### **8. Dural arteriovenous fistulas**

Dural arteriovenous fistulas (DAVFs) represent a specific vascular lesion that incorporates the dural suppliers of the cranium or spine, contributing direct arterial shunting toward venous structures. Venous hypertension can lead to cortical

#### **Figure 10.**

*A dural fistula fed by pial branches of the frontobasal artery was cured with onyx emblization. A, later internal carotid artery (ICA) angiogram showing a dural fistula fed by pial branches of the frontobasal artery and early opacification of frontal polar vein (arrowhead). Note the pseudoaneurysm on the feeding artery (arrow). B, superselective angiography by the microcatheter showing the pseudoaneurysm (arrow) and the fistula point (arrowhead). C, lateral internal carotid artery angiogram confirming complete occlusion of the aneurysm and the dural fistula.*

#### **Figure 11.**

*A cavernous sinus dural fistula was cured with tranvenous access. a, lateral view of the left carotid artery showed the left indirect carotid-cavernous fistula drained by the left superior ophthalmic vein and the left inferior petrosal sinus was invisible. b, under roadmap image, the left inferior petrosal sinus was catheterized. c, under roadmap image, coils were delivered through the microcatheter in the left cavernous sinus through the left inferior petrosal sinus. d, frontal view of the left carotid artery showed complete obliteration of the carotidcavernous fistula and the intact left internal carotid artery.*

dysfunction, venous hypertension, and hemorrhage when DAVF occurs intracranially [58]. However, dilation of venous structures along the spinal cord can lead to myelopathy from tissue engorgement and venous hypertension as well as physical compression when DAVF occurs in the spine. The complex anatomy and points of arteriovenous shunting make their management complex. EVOH-based embolic materials have been proved to be useful in the endovascular obliteration of these lesions [59] (**Figure 10**). When these materials are combined with balloon catheters, a deep penetration to the point of arteriovenous shunts can be achieved [60]. Transvenous approaches are also routinely employed and highly successful when arterial access to the fistula point cannot be achieved (**Figure 11**) [61].

#### **9. Spinal vascular malformations**

Vascular lesions of the spine and spinal cord can be categorized into intramedullary and extramedullary lesions [62]. These lesions are rare and comprise a heterogeneous spectrum of diseases. They were first reported in the 19th century with the autopsy-based classification of Virchow and Picard [63]. However, it was in the 1970s, with the advent of selective spinal angiography, that they became better understood [64]. Their identification and localization have progressed significantly with the development of imaging techniques [65]. Several classification systems have been proposed over time to describe vascular lesions of the spine [66].

#### **Figure 12.**

*A 49-year-old man presented weakness of two legs. a, left T-8 intercostal pedicle injection reveals the anterior spinal artery from above and below along the axis to supply the perimedullary fistula. b, under roadmap image a microcatheter was accessed to the fistulous point. c, control angiogram after onyx embolization reveals obliteration of the fistula with preservation of the anterior spinal axis.*

#### **Figure 13.**

*A 37-year-old woman presented with SAH caused by a juvenile type spinal AVM. A, the right subclavian angiogram. B, aortic artery angiogram. Reveal supply to the AVM in the vertebra and the soft tissue around with feeders arising from right subclavian and intercostal arteries. After treatment, aortic artery angiogram (C) and the right subclavian angiogram (D), partial embolization with coils to reduce the venous congestion was performed through the left radiculomedullary artery (arrow).*

The well known classification proposed by Anson and Spetzler in 1992 is type I, dural arteriovenous fistula (AVF); type II, glomus intramedullary AVM (**Figure 12**); type III, juvenile malformations (**Figure 13**); and type IV, perimedullary AVF [67]. With recent advances in embolic materials and devices in endovascular treatment, transarterial embolization plays an increasingly important role in the treatment of spinal AVMs. Complete angiographical obliteration of the nidus is not necessarily the goal of embolization, but rather, the treatment aims to reduce shunting volume and stabilize the symptoms [68].
