**5. Carotid-cavernous fistulas**

Carotid-cavernous fistulas (CCF) are usually treated endovascularly by interventional neuroradiologists or neurosurgeons. The endovascular treatment strategies of CCF has dramatically changed with the evolution of endovascular neurosurgery. A series of treatment modalities have been traditionally attempted, including the carotid artery ligation or trapping, muscle embolization via cervical exposure of the carotid artery, and balloon embolization with or without carotid artery sacrifice [41]. Brooks reported successful closure of a CCF with a muscle embolus introduced surgically into the carotid artery in 1930 [42]. Serbinenko revolutionized the therapy for CCF in the 1970s by introducing detachable intravascular balloons [43]. Though these lesions were often treated with balloon test occlusion and vessel sacrifice in the early stage (**Figure 6**), CCFs are now almost exclusively treated by an endovascular strategy with preservation of the internal carotid artery. Balloon embolization of CCF through a transfemoral access with preservation of the distal ICA has reduced the morbidity related to the treatment. This method is the primary therapy in most cases of CCF [44]. In addition to the balloon embolization, several other modalities have been deemed useful in the treatment of CCF in recent years [45], such as detachable coils, covered stents, ethylene vinyl alcohol copolymer (EVOH) and flow diverter placement [45, 46] (**Figure 7**). Transvenous embolization via the inferior petrosal sinus, superior ophthalmic vein and EVOH embolization modalities have been used with success [46]. Spontaneous resolution and/or thrombosis of CCF has also been reported, especially in indirect CCF, but

#### **Figure 6.**

*A 50-year-old male patient of carotid-cavernous fistula was treated with detachable balloon in 1985. A, right internal carotid artery (ICA) angiogram (anteroposterior) and lateral (B) showing a direct carotid cavernous fistula and early opacification of right cavernous sinus with no antegrade flow beyond the cavernous sinus. C, left vertebral artery angiogram (lateral) showing opacification of right cavernous sinus. Because the patient had no neurological symptoms with no contribution from the right ICA, no balloon test occlusion was performed before sacrifice of the ICA. D, fluoroscopic view of the head (anteroposterior) and lateral (E) showing the placement of one detachable balloon in the ICA of fistula site. F, left vertebral artery angiogram confirming complete occlusion of the fistula with reconstitution of the distal ICA blood flow from the vertebral artery. No retrograde filling of the fistula is seen.*

it is really rare. For less directly accessible lesions, superior ophthalmic vein access or direct puncture of the cavernous sinus and catheterization as an alternative approach to the cavernous sinus as well as transvenous routes can all be used [47].

#### **Figure 7.**

*A 33-year-old male patient of traumatic carotid-cavernous fistula was treated with preservation of the internal carotid artery. A, lateral view of the right external carotid artery showed an arteriovenous shunt between the anterior meningeal branch of the middle meningeal artery and the right superior ophthalmic vein (arrowhead). B, lateral view of the right carotid artery showed the high-flow carotid-cavernous fistula drained by the right superior ophthalmic vein and the right inferior petrosal sinus (arrow). C lateral view of unsubtracted image showed the inflated scepter C balloon (4 mm × 20 mm, Microvention, USA) in the right internal carotid artery (arrow) and the coils. Note the external carotid artery fistula was occluded with coils (arrowhead). D, lateral view of the left carotid artery angiogram after balloon-assisted onyx injection showed complete obliteration of the both fistulas and the intact left internal carotid artery.*

## **6. Arteriovenous malformation**

Exponential advances in catheter technology and refinements of embolic agents have greatly facilitated the rapid evolution of AVM embolization. In 1960's, Luessenhop and Spence performed the first embolization procedure on a cerebral AVM by surgically introducing silastic spheres made of methyl methacrylate into the ICA [48]. At that time, silk sutures, porcelain beads, Gelfoam, steel balls, Teflon-coated spheres, and polyvinyl alcohol were explored for AVM embolization with varying degrees of efficacy [49]. The use of these particle emboli was associated with a high complication rate secondary to inadvertent embolization of a normal cerebral vessel because the technologies and devices were not for direct nidus embolization.

Kerber developed the first calibrated-leak balloon, which allowed the direct embolization of an AVM nidus with the use of a rapidly solidifying polymer in

1976 [50]. This new system in combination with advances in imaging techniques and liquid embolic materials ushered in the modern era of AVM embolization. However, the use of calibrated-leak balloon catheters was associated with a high risk of arterial rupture. The introduction of liquid embolic agents, initially in the form of n-BCA, an acrylic adhesive [51], and advances in microcatheter and microwire design facilitated the distal catheterization of vascular malformations so that embolization of AVMs has evolved immensely over the last few decades to become a highly valuable therapy, and even an alternative in some cases, to surgery or stereotactic radiosurgery [52, 53]. The introduction of polymer non-adhesives (EVOH) allowed deep and extensive nidal penetration without the need for repeat distal catheterization and could be performed over long embolization procedure time periods [52].

Cerebral angiography detailed morphology study of the arteriovenous malformation involves evaluating the hemodynamic and anatomic characteristics of the lesion, including examination of the feeding arteries, the nidus itself, venous drainage of the lesion, coexisting aneurysms and arteriovenous fistulas [54]. A variety of strategies emerged, including multiple pedicle embolizations of the nidus. This was used by Lv et al. to "embolize AVM for cure" with low morbidity and mortality [55] (**Figures 8** and **9**). Endovascular surgery has specific indications in the treatment of AVMs, such as ruptured AVM, AVM of small size or deep locations, AVM with coexisting aneurysm and high flow fistula. Theoretically discussed and considered in the past, transvenous embolization is now being extensively explored, but its initial reports documented higher procedure-related hemorrhage rates [56].

#### **Figure 8.**

*A 40-year-old male patient presented brain stem hemorrhage caused by a small arteriovenous malformation. Anteroposterior angiography views (A-D) and lateral angiography views (E-H) . Showing a posterior pons arteriovenous malformation (AVM) fed by the left perforating artery of the basilar trunk (arrows in panels of a, E). Superselective angiogram demonstrating the ectasia of draining vein (arrows in panels of B, F). Angiograms after superselective onyx embolization showing complete disappearance of the AVM (arrows in panels of C, G). Postoperative images demonstrating onyx cast (arrows in panels of D, H).*

*The History and Development of Endovascular Neurosurgery DOI: http://dx.doi.org/10.5772/intechopen.97139*

#### **Figure 9.**

*A 5-year-old boy presented with intracranial hemorrhage caused by a small arteriovenous malformation. a, anteroposterior angiography of the left vertebral artery showing a small arteriovenous malformation (AVM) fed by the left posterior cerebral artery. b, anteroposterior angiography of the left vertebral artery after superselective onyx embolization showing complete disappearance of the AVM.*
