8.4

Discussion of Transvenous Occlusions

8.4.1 Approaches

8.4.1.1

IPS Approaches

(Case Reports I–III, Case Illustrations III and XI)

The IPS approach was initially described as an access route to the cavernous sinus (CS) for treatment of direct CSFs (CCF) (Debrun et al. 1981; Manelfe and Berenstein 1980). After its introduction as a venous route for embolization of indirect (dural) CSFs by Halbach et al. (1989a) in 1989, the IPS has been increasingly used by numerous other groups (Cheng et al 2003; Theaudin et al. 2007; Halbach et al. 1989a; Gobin and Guglielmi 2000; Kiyosue et al. 2004a; Kim et al. 2006; Meyers et al. 2002;

Yamashita et al. 1993; Annesley-Williams et al. 2001, Yu et al. 2007). Its frequent utilization as a venous approach to the CS is based on the following:

The IPS represents the anatomically shortest, thus technically least complicated and safest route. Particularly in patients where this sinus is involved in the venous drainage, the IPS approach is fast and straightforward in the majority of cases. Anatomically, its course is relatively straight, with a horizontal and vertical segment forming a wide angle that does not cause luminal narrowing or catheter kinking with friction that hinders advancements of coils.

Another advantage is the mechanical “stability” of the sinus. Its course along the petro-occipital suture (petroclival fissure), covered by the dura mater provides stability resembling a “pipe-like” structure. This stability is particularly important when a larger amount of coils need to be pushed through tortuous anatomy (e.g. like the SOV), eventually causing friction within the microcatheter, which may easily become a procedure-limiting factor. The IPS allows for advancing a guidewire or a microcatheter even when its lumen is narrowed, irregular or completely occluded due to thrombosis.

The topographical anatomy of the IPS opening into the jugular vein allows a relatively stable positioning of a large guide catheter within the vein, or sometimes even into the IPS itself. This makes navigating a microcatheter into the ipsilateral or

contralateral CS considerably easier compared to the retrograde navigation through the SOV, where positioning of a guiding catheter is less stable (Oishi et al. 1999; Halbach et al. 1989a, 1997; Yamashita et al. 1993).

It seems logical that the IPS was utilized early on as an alternative to transarterial balloon placement in direct CCFs with posterior drainage (Manelfe and Berenstein 1980). Despite its obvious advantages, some operators prefer alternate venous routes, commonly when the IPS is angiographically not recognizable (Goldberg et al. 1996; Hanneken et al. 1989; Hasuo et al. 1996), despite an increasing number of reported successful catheterization of such non-visualized IPSs (Benndorf et al. 2000a; Cheng et al. 2003; Halbach et al. 1989a; Yamashita et al. 1993; Malek et al. 2000; Roy and Raymond 1997; Quinones et al. 1997).

Halbach et al. (1988) described first the successful catheterization of an angiographically occluded, but eventually passable IPS in two patients. Further, Yamashita et al. (1993) were able to successfully catheterize the sinus in two cases, despite it being “angiographically occult”. Quinones et al. (1997) reported on a 30% success rate for IPS catheterization, including angiographically occluded sinuses.

It is noteworthy that in those “unsuccessful cases” the venous drainage pattern was usually not analyzed in detail. A fistula that would not opacify the IPS during the early arterial phase was commonly referred to as “not angiographically demonstrated” (Yamashita et al. 1993; Quinones et al. 1997), “angiographically invisible” (Yu et al. 2007), “not opacified” (Klisch et al. 2003; Kuwayama et al. 1998), “not patent” (Goldberg et al. 1996; Monsein et al. 1991; Krisht and Burson 1999), “not spontaneously opacified” (Monsein et al. 1991) or “hypoplastic” (Mizuno et al. 2001). The question of whether or not the IPS was opacified during the venous phase of the angiogram was not addressed.

However, in my experience, it is helpful to clearly distinguish between two types of negative IPS drainage patterns: (1) non-opacification only during the early arterial phase (= not draining the fistula), but during the late venous phase (= draining the brain), and (2) no opacification at all. Cases with the former disposition may be considered not worth attempting by some operators, although they have a high chance of successful catheter navigation into the CS (Case Reports II–III). An IPS that does not serve as a venous

outflow at all has likely undergone sub-total or complete thrombosis. As demonstrated in Case Report I and Fig. 8.3, this does not preclude the existence of anatomic communication, and thus the possibility of reaching the fistula site with a suitable tool.

The IPS may also serve as a draining pathway for the posterior fossa via the SPS; therefore, reading angiograms for decision-making must include the vertebral injections (Figs. 7.29 and 7.30). The only reliable proof of a thrombosed IPS is a direct sinogram via microcatheter, revealing an irregular, narrowed lumen, which nevertheless might be passable. A large volume jugular phlebogram, using several forceful injections from different levels of the proximal internal jugular vein, provides valuable additional anatomic information. It may reveal an either widely open IPS (Figs. 7.7 and 8.19), or a tiny residual portion of the thrombosed IPS, often visible as a small “notch”, (Figs. 7.42, 8.3, 8.14). According to Shiu et al. (1968), four main variants of the IPS/IJV junction exist and may play a role in the overall success rate of retrograde IPS catheterizations. Because of its complex architecture and the lack of connection to the IJV, the IPS could not be catheterized in 31% of the cases. This rate may be lower today with advanced catheterization tools, improved imaging techniques and better anatomic understanding of this region. It can be assumed that some of the plexiform-like appearing connections between IPS and IJV in this early work, performed in the 1960s, represented in fact thrombosed IPSs. The chances of success when using this route in an individual case remain hard to predict. As illustrated in Chap. 7, the existence of an aberrant IPS needs to be considered since it may be used as an approach as well (Benndorf and Campi 2001b; Calzolari 2002). Identifying such aberrant IPS (unusual deep termination) that enters as a small opening into a large vein, can be difficult if the catheter position is not at the right level, or not proximal enough to fill the IPS (Figs. 7.37 and 8.3). Several authors (Hanneken et al. 1989; Hasuo et al. 1996; Gupta et al. 1997; Jahan et al. 1998) have stated that catheter navigation through the thrombosed IPS may carry an additional risk of rupture, causing subarachnoid hemorrhage (SAH). The current literature reveals 14 cases of IPS perforation, of which some resulted in SAH and others in cerebellar or extradural hematomas (see Table 8.3). Ten cases were successfully managed by endovascular means (Kim et al. 2006; Halbach et al. 1991a; King et al. 1989). Halbach et al. (1988) observed a rupture with SAH in two patients with a direct CCF; both were suc-

cessfully treated by deployment of coils at the rupture site. This group also reported on a patient with a DCSF and intracerebellar hemorrhage after perforation of the IPS who partially recovered (Halbach et al. 1991b). King et al. (1989) published a rupture of the IPS during transvenous approach to a carotid cavernous fistula, causing a minor SAH that was subsequently managed by surgical exposure of the CS and injection of IBCA. Yamashita et al. (1993) described IPS rupture with extradural extravasation of contrast which stopped spontaneously without clinical consequences. Inagawa et al. (1986) reported a patient who deteriorated after an unsuccessful occlusion via IPS approach. This deterioration was attributed to thrombosis of the IPS, and the patient was treated transarterially by balloon occlusion.

Kim et al. (2006) recently presented a series of 56 patients with three IPS perforations. The rate of sinus perforation is higher than reported by others but was controlled in all three cases by coil deployment at the rupture site with no significant neurological sequelae. The authors emphasize that sinus rupture may occur even when using supple guidewires and microcatheters without providing details of the devices being used. It raises the question of how gently (or forcefully) have these tools been manipulated.

In the 45 patients with DCSFs studied here, one perforation during catheterization of the inferior petrosal sinus was observed (Benndorf et al. 2004) that remained clinically silent.

Apart from transvenous embolization of DCSFs, IPS catheterizations have been used extensively as a diagnostic means for venous blood sampling (petrosal sampling) in patients with Cushings disease. The literature shows that this procedure may be associated with complications as well (Shiu et al. 1968;

Bonelli et al. 1999; Miller et al. 1992; Sturrock and Jeffcoate 1997; Seyer et al. 1994; Lefournier et al. 1999; Gandhi et al. 2008) (Table 8.4)

Bonelli et al. (1999) recently reported about a patient who developed elevated blood pressure, headache and confusion during the procedure due to sinus rupture causing severe SAH, after using a Tracker-18 microcatheter. The authors also describe headaches and nausea without sequelae in three other patients (Bonelli et al. 2000.)

Shiu et al. (1968) already documented the rupture of a pontine vein during cavernous sinography for diagnosis of a pituitary adenoma. As demonstrated in Tables 8.3 and 8.4, more serious complications are observed during petrosal sampling than during transvenous catheterization for CSF occlusion.

While SAH occurs here less frequently, brain stem infarction due to compromised venous drainage is observed more often. The reason for that may be the use of (relatively large) 5-F diagnostic catheters, especially when placed bilaterally as is often the case for diagnostic sampling in patients with Cushings disease. Gandhi et al. (2008) observed a patient who developed a partially reversible brainstem infarction, requiring intubation and tracheostomy. The authors discuss whether a variant venous drainage pattern or an outflow obstruction, induced by the diagnostic catheters, could have been the cause. Un-

fortunately, their figures are not supportive of either theory and appear misinterpreted with regard to the venous anatomy. However, it seems quite plausible that placement of a 4-F catheter becomes occlusive, forcing not only contrast into the pontine and mesencephalic veins, but also compromising normal venous circulation (Fig. 1b there).

Overall, the risk of venous ischemia due to catheter manipulation during endovascular therapy is relatively low, since small catheters (2- to 3-F microcatheters) are employed and are commonly used unilaterally. Consequences may be serious though

when a 5-F catheter is introduced into the IPS blocking the posterior venous outflow (Theaudin et al. 2007).

Furthermore, it can probably be assumed that in case of a thrombosed IPS, the normal venous circulation of the pons and brain stem has already accommodated and uses collateral circulation. Thus, the blockage of this sinus by a guidewire or a microcatheter will less likely cause a relevant compromise of the normal venous drainage with subsequent venous infarction. A rupture of the IPS causing a clinically significant intracranial hemorrhage may only occur if this sinus also drains an arteriovenous fistula and is thus exposed to increased intravascular pressure (King et al. 1989).

Two possible mechanisms may cause hemorrhagic complications during endovascular manipulations (Halbach et al. 1991b): First, a sudden increase in intravenous pressure during contrast injections; second, perforation of the thin venous wall during advancement of the sharp guidewire tip, stiffened by the catheter and narrow vascular structure. The first can be avoided by performing careful injections as a “test” under a blank road map to control catheter position (Benndorf et al. 2000a). The second should remain extremely rare if a microguidewire is advanced very slowly under bilateral fluoroscopy. Under these circumstances, the use of a loop at the tip while advancing the wire within the thrombosed IPS was found to be very helpful. The softness of smaller devices such as 0.010s or the 0.012s guidewires, provides better conformability to the specific anatomy of the IPS and prevents entanglement in an irregular, trabeculated or even thrombosed venous lumen (Benndorf et al. 2000a). Advancing a supple 0.012s wire that can easily be formed into a loop is less traumatic than using a straight tip, particularly if the catheter is already wedged. Because the IPS is mainly located in the extradural space, or is at least partially covered by the dura, rupture of the IPS resulting in a hemorrhage is hard to imagine unless the dura mater is perforated. Perforation of the dura mater requires a critical level of mechanical stress, as pointed out by Shiu et al. (1968), who found it almost impossible to perforate the dura adjacent to the IPS in studies performed on post mortem material. To reduce the risk of perforation, the author prefers not to use a stiff 0.035s wire stiff as suggested by Goto et al. (1999) and others (Oishi et al. 1999; Kirsch et al. 2006). As reported by Oishi et al. (1999), this may cause dissection of clival dura and result in permanent 6th CN palsy, due to damage

of the nerve when passing Dorello’s canal or due to direct injury by the guidewire. A 0.035s wire cannot be used as a loop and has to be advanced in “KuruKuru technique,” like a “drill”, to recanalize the IPS. This technique, although advocated by some authors (Oishi et al. 1999; Goto and Goto 1997; Nemoto et al. 1997), may carry the risk of perforation or damage to the 6th CN, especially when its lumen is narrowed and the wire tip becomes a small spear. A so-called “microcatheter pull-up technique” using a second microcatheter with a snare has been recently suggested by Hanaoka et al. (2006) as an alternative. Gobin et al. (2000) used a left IPS-ICS approach to place a microcatheter in the right IPS facilitating catheter navigation from the right IJV into the CS in a bilateral DCSF.

Case Illustration II (Fig. 8.31) shows that in some cases, even two microcatheters can be navigated through a thrombosed IPS. Such a “dual IPS approach” can be very useful in cases with multidirectional venous drainage. It enables one to selectively disconnect one venous drainage (e.g. leptomeningeal, cortical) while securing catheter position in another (anterior) compartment and help to avoid compartmentalization of the fistula.

Case Illustration X (Fig. 8.38) shows the staged management of a complex AVF involving the bilateral CS and the clivus. The CS AV shunts were approached and obliterated utilizing the (thrombosed) IPS approach. The intraosseous lesion was successfully occluded in a second session using an intraosseous venous channel 3 months later.

8.4.1.2

Thrombosed Cavernous Sinus (Case Report III)

As demonstrated, standard 2D-DSA may easily fail to opacify the IPS or the CS. Beside hemodynamic factors, thrombotic processes within the CS or the IPS may play a role in the failure to visualize the sinus as well (Halbach et al. 1997). Highly flexible, supple microcatheters and guidewires are not only useful when navigating through a thrombosed IPS, but also when passing intracavernous trabeculae or thrombi that may not be easy to identify, but are often present in DCSFs. The CS can be divided into anteroinferior and posterosuperior compartments, separated by the intracavernous ICA. Despite intracavernous septi, manipulation and advancement of microcatheters is usually not very difficult in most directions, ipsito contralateral or anterior to posterior. Despite the importance of modern an-

giographic equipment, profound knowledge of the complex anatomic structures and a good three-di- mensional understanding of the CS are required for optimal use of tools and devices. Traditional crosssectional imaging techniques, although improved over the last years (Schuknecht et al. 1998), still do not provide satisfactory spatial resolution. Even currently available high-resolution DSA that enables depiction of the smallest AV shunts with certainty is limited in its capability to display small venous structures. Angiographic computed tomography (ACT, DynaCT) may improve CS visualization and will likely contribute to a better understanding of such complex vascular structures (see Chap. 7).

The reasons for incomplete CS visualization by 2D-DSA are threefold. First, non-opacified blood draining from other tributaries via the same venous structures, causing washout effects. This becomes obvious in cases where a CS that is angiographically “silent” (after arterial contrast administration) becomes clearly visible in a jugular phlebogram. Second, thrombotic processes, frequently associated with DCSFs (50%) (Mironov 1994), may be responsible for non-opacified CS compartments in the same way they are for a non-opacified IPS. It has been suggested that thrombosis of the IPS is one cause for acute progression of the ophthalmological symptoms (Halbach et al. 1992, 1997), as the blood draining here is rerouted towards the SOV (Satomi et al. 2005). Acute thrombosis of the IPS is the main reason for most angiographically “not-visualizable” sinuses that are still passable with a microcatheter (Halbach et al. 1997). Third, local hemodynamics play a role, since the fistulous compartment, usually with higher pressure, is more difficult to fill using a manual intravenous contrast injection, even when performed via microcatheter placed in the CS (Halbach 1997). Finally, although some authors doubt that a true trabecular structure exists (Taptas 1982; Bedford 1966), separation by intracavernous filaments and septi causing compartmentalization (Debrun et al. 1981; Inagawa et al. 1986; Chaloupka et al. 1993; Mullan 1979;

Butler 1957; Ridley 1695; Winslow 1734; Teng et al. 1988a) may influence angiographic appearance of the CS as well. Thus, manipulation and navigation of microcatheters inside the CS can be difficult in some cases. Placement of a microcatheter into the desired location via one single approach may be impossible (Yamashita et al. 1993). If more than one fistula site exists that cannot be reached using one venous route, two or more approaches may be used

simultaneously in one session (Case Illustration II and III).

Chaloupka et al. (1993) reported a CS compartmentalization in a patient with a DCSF in whom the fistula site in the anterior compartment was not reachable from the posterior CS. This particular disposition was called “true anatomical compartmentalization”, since no communication was seen either in the angiograms or in the selective venograms via microcatheter placed within the CS. However, this situation resembles the one described in Case Report III, where catheter advancement was eventually possible indicating intracavernous thrombosis rather than anatomic separation. Thus, it appears doubtful that such a conclusion can be made based on contrast injections and guidewire resistance only. Quinones et al. (1997) reported one case (Figure 2 therein) in which a petrosal venogram did not show a direct connection between the IPS and the CS and that subsequently underwent SOV embolization. Taking into account the limitations of angiographic appearance due to local hemodynamics and thrombotic processes, catheter navigation into seemingly “occluded CS compartments” may be feasible and is justified if gently performed, especially when more aggressive endovascular or surgical techniques can be avoided.

8.4.1.3

Transfemoral Facial Vein/Superior Ophthalmic Vein Approach (Case Report IV)

The transfemoral approach through the facial vein or the SOV was introduced by Komiyama et al. (1990) and has been used by various groups with different success rates since (Cheng et al. 2003; Theaudin et al. 2007; Kim et al. 2006; Annesley-Williams et al. 2001; Biondi et al. 2003). It may be an effective alternative route and is indicated when the SOV is significantly enlarged due to anterior drainage, and the IPS cannot be passed. This approach is usually feasible when the SOV is dilated enough and allows even cross-over and packing of the contralateral CS. It may be technically challenging though, if the SOV is tortuous, stenosed or thrombosed (Case Report V).

Two aspects seem important. First, the SOV approach is in general less feasible than the IPS approach, due to the less favorable anatomy. There is a longer distance to be catheterized combined with tortuousities of the angular and superior ophthalmic veins. Furthermore, the guiding catheter usu-

ally has a mechanically less stable position within the IJV or the facial vein than for the IPS approach. Unstable position of the guiding catheter may easily become a procedure-limiting factor in cases where catheter advancement is already difficult due to the friction in the loops of the SOV. Thus, it is advantageous to place a 4-F guiding catheter in the facial vein, close to its connection with the angular vein. In contrast, some operators recommend positioning the guiding catheter in the IJV to avoid impairment or stasis of the venous outflow that may cause ophthalmic or neurological complications (Biondi et al. 2003). Cheng et al. (2003) suggested “rubbing” over the patient’s face toward the orbit to support advancement of the microcatheter.

The transfemoral SOV approach appears particularly feasible in patients with enlarged ophthalmic and facial veins. It may be technically challenging or even impossible in cases with low-flow fistulas and significant elongations of the angular and ophthalmic veins, or when associated with stenotic segments or thrombosis (Miller et al. 1995; Teng et al. 1988b). Biondi et al. (2003), in the first series of seven patients, achieved anatomic cure in six cases (85.7%), clinical cure in four (57%) and improvement in two (28.5%). In one patient catheterization of an occluded SOV failed. It was emphasized to remember the two anatomic roots of the SOV origin for full understanding of the angioarchitecture (Figs. 3.9, 3.10 and 7.31). Although the inferior SOV root should be easier to catheterize from the facial vein because of its relatively straight course, in most cases successful navigation is performed through the superior route. The reason for this may be that the inferior root is often poorly visualized (Biondi et al. 2003), in addition to valves that have been reported by some authors (Biondi et al. 2003; Testut and Jacob 1977; Hou 1993).

The author’s personal experience confirms the one already made by Mullan et al. (1979) and Halbach et al. (1989a), who struggled with technical difficulties when navigating through the loops of the angular and ophthalmic veins. Although this has become technically easier with improved catheterization tools, the SOV anatomy not only remains tortuous compared to the IPS, but also may show an abrupt angle or narrowing at the level of the superior orbital fissure (Hanafee et al. 1968). Manipulation of catheters and guidewires in the SOV may lead to temporary venous outflow restriction, thrombosis associated with transient aggravation of exophthalmos and vision loss (Gupta et al. 1997;

Biondi et al. 2003; Devoto et al. 1997). When the CS cannot be reached or the fistula is not occluded in the same procedure , a serious clinical condition may develop.

This latter observation was made by other operators (Halbach et al. 1989a; Devoto et al. 1997), and in two of the author’s patients, who experienced transient aggravation (Cases V and VI), and represents a clear disadvantage of this approach. Another potential complication of the approach through the SOV is the rupture of the vein with intraorbital bleeding and vision loss (Wladis et al. 2007; Leibovitch et al. 2006; Hayashi et al. 2008). Uflacker et al. (1986) emphasized that the age of the AV shunting plays an important role for the development of a thickened venous wall. Although animal experiments have shown that histological changes of a reactive wall hypertrophy start to develop approximately 7–10 days after establishment of an AV shunt, catheterizing the SOV in cases with longer-standing AV shunts may be safer. Interestingly enough, Sattler (1905) already pointed out that the thickness of the venous wall may increase four times and numerous elastic fibers develop due to the elevated pressure. DCSFs are often longstanding shunts, and fresh arterialized veins are to be found more often in direct CCF fistulas with short history. Wladis et al. (2007) reported recently an acute intraorbital hemorrhage during transfemoral SOV approach that led to an orbital compartment syndrome with vision loss due to transient flow arrest in the ophthalmic artery. This complication, erroneously called “obstruction” by the authors, was most likely caused by acute increase in intraocular pressure, exceeding the perfusion pressure of the orbit. Stagnation of ophthalmic artery flow may result in central retinal artery occlusion, which can cause significant irreversible retinal damage when exceeding 240 min (Hayreh et al. 2004).

In cases, where the facial vein cannot be reached by transfemoral approach, direct puncture at the mandible has been suggested as an alternative route (Naito et al. 2002). Scott et al. (1997) reported five patients undergoing ultrasound-guided direct stick of the facial vein (transcutaneous approach).

8.4.1.4

Approaches via the Middle Temporal Vein or the Frontal Vein (Case Illustration I)

Basically all afferent and efferent veins connected to the angular or ophthalmic vein, or directly to the