distally with silicon vascular loops. These loops are passed through small pediatric feeding tubes to control the bleeding while advancing the catheter using a two-person technique (Miller 2007).

For all SOV approaches, the packing of coils is performed in the reverse order compared to the IPS approach, starting at the most posterior aspect of the CS and finishing the coil packing at the SOV–CS junction. In this manner, the coil packing begins at the posterior or contralateral compartment of the CS; the disconnection between CS and SOV is done as the last step. At the end of the procedure, the vein is manually compressed for a few minutes before the skin is sutured.

8.1.2.3

Transorbital Puncture of the Superior or Inferior Ophthalmic Vein (Case Report VI)

Failure of all previously described approaches justifies a more aggressive technique, in the same or a subsequent session. A bi-plane road map is obtained using the 4-F diagnostic catheter demonstrating the course of the vein deep in the orbit. Under sterile conditions, a 21or 22-gauge needle (e.g. Terumo UTW 21 or micropuncture set) is gently advanced along the medial wall of the orbit posterior to the globe, using bi-plane fluoroscopy. When the needle reaches the deep orbit, the SOV or the IOV is carefully cannulated and a small microcatheter (Tracker-10) is introduced. The IOV is punctured by advancing the needle along the inferior orbital rim (White et al. 2007). After the microcatheter is advanced into the CS, coils are deployed, as described above. Puncturing an arterialized vein within the orbit is a delicate maneuver. Stabilizing the needle is crucial while manipulating a microcatheter or pushing coils into the CS. Losing this access can not only jeopardize the procedure, but may also cause intraorbital hemorrhage with potential vision loss. Avoiding excessive tension on the fragile venous wall by a lesser dense packing within the SOV may be advisable.

8.1.3

Other Techniques

For alternative transfemoral, transcutaneous and transorbital CS approaches, including the superior petrosal sinus (SPS), pterygoid plexus (PP), the facial vein (FV), the middle temporal vein (MTV), the frontal vein (FV), superficial middle cerebral vein (SMCV) and direct puncture of the CS, see discussion below.

8.2

Embolic Agents (Figs. 8.5–8.13)

To cover the wide range of various embolic materials and their handling is beyond the scope of this chapter. Embolic agents of particular interest for transarterial or transvenous occlusions of dural CSFs will be described below.

8.2.1

Polyvinyl Alcohol (PVA) and Embospheres

PVA particles (Contour PVA, Boston Scientific, Fremont; TruFillTM PVA, Cordis Endovascular, Miami Lakes, FL) have been employed for a long time in a wide range of applications and are used frequently in preoperative embolization of vascularized tumors such as meningiomas, glomus tumors or capillary hemangiomas (Bendszus et al. 2000; Manelfe et al. 1976; Wright et al. 1982; Berenstein and Graeb

1982; Kerber et al. 1978). In the 1980s and early 1990s, PVA was also used for embolizing brain AVMs (Scialfa and Scotti 1985). PVA particles can be injected wherever liquid embolic agents are considered unsafe, and coils are unsuitable for anatomic or hemodynamic reasons (Wright et al. 1982; Kerber et al. 1978; Jack et al. 1985). The particles are manufactured by different vendors in a size between 45–150 μm and up to 700–2000 μm, and are selected based on the caliber of the vessel in the targeted territory. One longstanding disadvantage of PVA has been the fact that these particles not only varied in size (ranges), but also had an irregular surface causing aggregation, clumping and occlusion of catheters and proximal vessel segments. In addition, the particles showed a tendency to swell after being in a contrast suspension for some time and usually had to be replaced by a new mixture several times throughout the treatment session.

Newer PVA particle types come as hydrophilic microspheres in a calibrated size (Contour-SE, Boston Scientific). They are naturally opaque with a more uniform size distribution, a wider range of sizes and come pre-hydrated in saline in a prefilled syringe.

Alternatively, Trisacryl gelatin microspheres (Embospheres, Guerbet Biomedical, Louvres, France) can be used and may offer some advantages because they are precisely calibrated at 100–300 μm and have fewer tendencies to aggregate (Laurent et al. 2005; Beaujeux et al. 1996; Derdeyn 1997). A recent comparison has shown that they produce less