We'll go over the thought process, what to treat and why to treat, and some of the techniques that we have available for us to do that. The only table that I have in the whole presentation is this, and what you need to remember from that is two things, that the dural arteriovenous fistula, they have the pathology in the dura, not on the surface of the brain in the pia, meaning that the feeder vessels has to go through the dura at some point. That's number one. Number two is that you need to know if there is a cortical venous reflux or not, because that affects the presentation for those patients. And the third thing, you need to know if actually the connection is at the level of the sinus or not. So the distinction in those classification is mainly related to if it's that connection between the artery and the vein without going through the sinus, which is a type three, or what's actually connecting through the sinus and then refluxing into the cortex of the brain. So that's the main thing you need to remember about the classification. Type one, we rarely treat. You have the direct connection from the arterial system into the sinus, and there's no venous reflux, so there's very little indication to treat those patients. And if you need to treat that, you need to disconnect the arterial connections at the level of the dura. Type two is a little bit more different. So you have the feeder vessels, they go into the sinus. They can have anti-grade or retrograde into the sinus. But more importantly, you have now the pathology that you have a venous reflux. The pathology, the pathophysiology at the level of the dura, and the drainage is actually now into the cortical vein. So if you have that, you have that cortical vein, now under pressure, you're going to have venous hypertension, you're going to have headaches, you're going to have seizure, bleeding. And the main indication for the treatment is that you need to disconnect that pathology where you have the venous reflux. You could do that at the venous side, that's one option. That's not durable if you leave the fistula patent. The second option is actually to go and disconnect the feeder vessels at the arterial side. And the third option, if the sinus is not functional, is actually to go and sacrifice the sinus itself. So that is another option, and probably the more durable option. So type three fistula, we need to remember over here, is that the sinus is preserved. There's no problem at the level of the sinus. There's feeders that come in, they connect to the vein. There's multiple feeders, a lot of feeders coming from the side. And the pathology is actually at the level of the vein. Any treatment that you need to do, you need to ensure that you're disconnecting all of those arteries from the vein. One option to do that is you go and try to close every single feeder vessel, or you go through one of the feeder vessels and you occlude the vein itself. By doing so, you close all the feeding vessels because there's no outflow. So we'll go through a couple of those cases and we'll try to highlight those principles that we're talking about. So the first one is a patient comes with a cerebellar hemorrhage, and you do an angiogram and you see here that there's an early draining vein that you start to see. So we think that is the site where the fistula is connected. The next question is that is that connected through the sinus or not, and we don't think it's connected through the sinus. Anatomically, where is that located? And this is the level of the tentorium. So this is at the superior aspect of the cerebellum, a common location to have those kind of fistulas. This is a type 3 fistula because the connection is between the artery and the vein, and there's no connection with the sinus in between. So the treatment for that, you need to get an embolic agent that you're using to get all the way into the vein to disconnect the vein, or actually do surgery and disconnect that. So this particular patient has fetus from multiple locations. One of them is from the superior cerebellar artery, and you have this small microcatheter here. This is MAGIC, which is probably the smallest microcatheter we do have, selective injection, and you can see this is actually going through the dura, and that's the site of the fistula. This has the connection between the artery and the veins, and this is the vein which is running now at the surface of the cerebellum. So any treatment you need to do, you have to ensure that this is disconnected. So this is the glue cast after that. So we're injecting glue from here all the way down, getting into the vein, closing the vein, and we have also glue that comes into the other fetus from the other feeding vessels. So that's one option of treating that, that is with the glue. This is actually with dextrose push 1 and 6. So we have to get this all the way down. We have a really distal axis, so the best way is to use diluted glue, and the question is that the more concentrated the glue, the faster it takes to polymerize. The more diluted the glue, the longer it takes to polymerize, and it can permeate more distally, and you want it to permeate more distally. So this is the angiogram post, and you can see the fistula now is not visualized. So another example, similar scenario, cerebellar hemorrhage, and this is an angiogram for dissipation as well. Kind of hard to figure out where the side of the fistula, but we kind of think that there's this early draining vein that comes all the way to the front, and we think somewhere around there is the side of the fistula. Again, this is a dural fistula, which means that the feeding vessel is going to be from the dura, and the closest side of the dura to us, this is the tentorial edge that you can see. So this is common location in a supracerebellar region. This is going through the, again, superior cerebellar feeder vessel, selective injection, and you can see the side, the feeder vessel that goes through the tentorial edge, and then this is the early draining vein that comes all the way at the most superior aspect of the cerebellum and interior to the cerebellum. So the aim for the treatment is to try to embolize that vein, disconnect that vein. There's multiple other feeders from elsewhere, but if you close the vein, everything else will shut down. This is the glue cast at the end of the embolization. You can see the whole thing is now filled with the glue cast, and this is the angiogram post-embolization. This is a video for the glue injection itself. So we are now going to put the micro catheter all the way into the superior cerebellar artery. Selective injection, you can see a bunch of the feeder vessels that goes in the tentorial edge and the early draining vein. This is under roadmap guidance, so the only thing that you see now is what you are injecting. So this is the glue, which is being injected. You're filling all the feeding vessels, it's coming down, and ultimately they're going to go up and start going into the vein. And you really want to cast that vein, you really want to disconnect that vein, and if you don't do that, they're going to have a bunch of other feeders that are going to come from other places and will ultimately recanalize that. Once you're happy with that, then you pull the micro catheter and you're pretty much done with your procedure. This is the angiogram at the end, and you can see that there's no early draining veins anymore. CT scan post-embolization, again, it helps you actually to know where is the site of the vein, where is the site of the fistula, again, within the site of the fistula at the most anterior aspect of the tentorial edge, and this is the draining vein that was gone at the surface of the cerebellum. Another option of treatment is, instead of using the glue, you can use the Onyx. The Onyx has different advantages as compared to the glue. You can control it much better. And initially, you know, about 20 years ago, the only option that we had was the glue. Now we have the Onyx, now we have better technology with balloons that can work with Onyx. This is a patient who comes in with also cerebellar hemorrhage as well. And again, type 3, we're still talking about type 3 fistulas at this point because there is no connection to the sinus in between. Multiple feeders, you can see that from the occipital artery, and you're going to try to, you know, map where is the site of the fistula for this particular patient. And there's multiple feeding vessels that comes all the way from everywhere pretty much, and everything comes in the dura. This is just below the level of the tentorium, and it seems that this is the common pathway for all of those arteries. And again, we don't think it's just coming to this vein, which ultimately gets down and there's a venous aneurysm, which make it actually great for a dural fistula. Again, this is the tentorial edge. You know, we don't think it's going to the sinus itself. Multiple other feeders that you can see here from the vertebral artery, the muscular branch coming to the same location, and from the tentorial branches of the internal carotid artery. And again, you can see that this is coming to the same location. So the arrow is what we think is the intradural component of the vein, or the site of the fistula. Any treatment you need to do, you have to make sure that you block that common pathway for all those feeders coming in. So this is the tentorial edge. Again, if you need to do surgery, you know what it is. So this is an old case before we have the balloon compatible, the onyx balloon compatible. So here we're injecting the onyx, but pretty much into the distal, into the occipital artery. You have a lot of reflux. You have to allow a lot of reflux for the onyx to permeate all the way in. And again, the aim is to try to fill that vein. And by doing that, you're actually filling multiple areas on your way. This is not the regular road map. This is a delayed road map on the venous face. So you can see actually all the veins on top of the onyx injection. Here we don't see the veins on top of that. This is the glue cast at the end, and you can see, I'm sorry, the onyx cast at the end. And you can see that the onyx permeated backward into multiple other feeding vessels, including branches that comes from the vertebral artery, from the middle meningeal, from the internal, from everywhere. And you can see that coming all the way to the other feeding vessels. And the aim of the treatment, again, is to go where the connection between the arterial system and the venous system, and we think it's somewhere around here. And you really need to block that. If you block that, it doesn't matter, you know, what you do with the rest of the feeding vessels. This is the tentorial edge, and this is the angiogram post the venous phase, showing that actually this is all infratentorial, and the sinus is preserved. Again, in type 3, type 4, you know, there's no role in doing sinus sacrifice, because the pathology is not at the junction of the sinus. Another example, so this patient comes with hemorrhage under one surgeon, different hospital. They thought she had some AVM, transfer her to us. And this is an angiogram occivital injection. You can see there's multiple branches, and the branches become smaller as they get to the level of the side of the vein. And this is probably the side where all of those feeding vessels are coming into. This is the intra-dural component of that vein. That's the side of the fistula, and from there you have the venous reflux. And this is the venous reflux which is causing the venous hypertension, symptomatology, ultimately the bleeding. So again, this is a, you know, different selective injection from the internal maxillary. You can see there's a lot of feeders from the middle meningeal. Again, you have to kind of map those on top of each other. So whatever we look from, we saw from the occivital artery kind of matches what we saw from the middle meningeal, and the pathology, it seems to be at that location. That's what you need to sacrifice. That's the area that you need to get the embolic agent to occlude. So that case was before we had the balloon, the septal balloon, which is the DMSO compatible balloon. And what we're doing here is we're actually inflating a balloon into the occipital artery. We're trapping another microcatheter which is beyond that area, and we're trying to inject the onyx from that location. This is a super selective injection from there, and we think that the side of the fistula is somewhere around here. Again, the tip of the microcatheter is all the way up, and there's a balloon which is more proximally trapping that to prevent the reflux. We're injecting the onyx, and you can see the onyx is going backward into the other feeding vessel, but we haven't get to the site where it should get, which is that vein. And here we started to get into that location, so we're making good progress. This is the end of the embolization, and you can see that what we want to do is we want to try to fill that part where the intradural component of that vein is, where all the feeders are coming together. By doing so, you're actually taking the rest of the feeding vessel, but again, that's not the aim. The aim is just to disconnect that portion. This is the angiogram at the end, and you can see the whole fistula is gone. The CT scan post, this is all the onyx cast, which is in the intradural component. And the angiogram after the procedure, the venous phase, you can see actually there is no compromise of the venous outflow for that hemisphere. This is the video for that particular patient, so we're looking at the regular angiogram, and this is with the balloon inflated over here, proximally the tip of the microcatheter over there. We're trapping the microcatheter, and we're using that technique to allow us to have the distal migration of the onyx without having a proximal reflux. And we're making some progress over there, and as you continue the injections, ultimately the onyx will permeate all the way into the area that we wanted to ultimately occlude, which is the junction of that vein, which is the intradural. And you really want to pack that really well, because if you don't do that, the blood's going to go around that onyx, and the fistula's going to recanalize. So by doing so, that fistula has been treated. Another example is this patient coming with a massive hemorrhage, and this is a 3D angiography of the internal carotid arteries, multiple fetus coming from the internal carotid artery, and ultimately all going to this vein that connects ultimately with a large aneurysm intradurally. This is the angiogram. The site of the fistula is that location. Everything here is intradural. That's where the vein becomes intradurally. So if you want to treat this patient, you want to make sure that you disconnect that location. Again, this is an internal injection. External injection, the same thing, the same common pathway. This vein needs to be disconnected. And this is the diagnostic T, and this is the site of the vein. So we know what is that vein. We know anatomically where is it located. This is the venous aneurysm that presumes the source of the bleed. So this is the other projection, again, showing that intradural component of that vein. And this is with a new generation of balloons, the susceptor balloon, which is the MSO-compatible balloon. And we're putting this balloon into the external carotid artery branches, selective injection, and we want to get the anus to get to that point. And that's the anus cast at the end of the procedure, and this is the angiography at the end, showing complete exclusion of the fistula. Again, you don't need to fill every single feeding vessel. This is the internal injection at the end. We did not fill any of those feeding vessels, but if you occlude the common pathway on the venous side, all the feeding vessels from the other arteries will completely shut down. Just remember that. This is the diagnostic T at baseline. We think that's the site, the intradural portion where the fistula is located, and this is the regular CT post-procedure, and that's where the anus gets into. That's exactly where we want it to be at. This is the video for the onyx injection. The balloon is inflated in one of the branches from the external carotid artery, and this is the edited version of the video. It's much longer. And you want to get it all the way to that region. And you can see because of the high flow, you have a little bit of onyx, which is kind of goes all the way this into the venous system. But we want to really pack this region very, very, very tight so that we block all the feeding vessels which are coming from the internal as well. Another example of a patient who comes in with a subdural hematoma, intracranial hemorrhage, again taken to the operating room at a small hospital in the suburbs. And he got in trouble, had a lot of bleeding. He thought it was an AVM. There was a lot of red veins. So he put a bunch of clips that he thought he, I thought, I think he just put them on the arterial normal arteries. And he had a CTA and then sent the patient to us. And you can see that, you know, this is the tentoral edge. And there's a large vein that comes in. There's a venous aneurysm. Again, this is the large vein that you can see early on. And there's a large venous aneurysm. So we think there's a dural fistula over there. We don't think it's an arteriovenous malformation. This is the angiogram which confirms that. Selective injection from the external. This is a type four fistula. Again, there's no sinus in between the arterio and the venous system. So again, we have, there's no role for sinus sacrifice in those particular patients. Again, we think this is the common pathway for all the feeding vessels ultimately gets into this aneurysm and have a multiple cortical veins. One thing that you want to keep in mind is that you want to look at the venous phase of that hemisphere. And the venous phase of that hemisphere is just completely normal sinus. The sinus is not involved with the pathology. Just remember to look at the venous phase. Again, all the veins are congested and there's a lot of venous hypertension in that particular situation. This is from the left ECA. Again, everything is feeding to the same area. That's the area that you need to disconnect. And you do that with whatever modality that you want to do. In this particular situation, we're using a receptor balloon with the onyx and this is the balloon over here inflated. This is before injecting the onyx. And this is the progression of the onyx gas as you start the embolization process. Again, the aim is to get it into that vein. You need to continue doing that until you get to that aim. Otherwise, the vessel is not treated and you better do that in one shot. It becomes much harder later on. Again, we're really pushing all the way that until we get to the venous aneurysm to ensure that everything is being disconnected. And this is the angiogram at the end. This is the site where the vein was and the external injection showing no filling. Unsubtracted image, again, that's the site of the fistula. It's just really occluded with the onyx gas. The video for that, this is the receptor balloon inflated into that feeding vessel. So you don't need to wait to form a plug. You just can start with the injection of the onyx immediately. And you can see the onyx is permeating. Again, it's going to go into multiple vessels. It's going to go into contralateral feeding vessels. It's going to go into multiple arteries in the dura. That does not solve the problem. To fix the problem, you need to get the onyx to go into the draining vein, the common pathway, and disconnect that. And that's what's happening over here. It's ultimately getting into that location. Again, you reset the road map. You wait. You reset the road map. You redirect it until it gets to where you want it to be. And here, we're making some progress, ultimately. And you can see that it becomes much more dense at the end. So everything that we've talked about so far is to treat the direct connection between the arteries and the vein in type 3 and type 4 dura fistula. Well, the disease which is much more difficult to treat is the type 2 fistula, where the pathology is at the level of the sinus. The blood comes from the arterial system, goes through the sinus, and then from the sinus goes back to the surface of the brain, causing venous hypertension. This is a lady that comes in with a seizure. And this is external injection. This is a 3D from the external carotid artery. And you're seeing the whole venous system. And the reason why you're seeing that, because there's multiple feeding vessels ultimately comes to this area. So we think that's the site of the fistula. And from there, retrograde into the sinus, retrograde through multiple cortical veins, ultimately filling pretty much the whole surface of the brain. Severe venous hypertension. So the pathology here is at this location. You can come trans-arterially and try to block all of those feeding vessels, or you can come transvenously and occlude that common pathway if you can do that safely. And the way to know if you can do that safely or not, look at the venous outflow of that hemisphere. And if nothing is draining to that side, that's a good indication that actually the sinus is a non-functional sinus. So because the sinus was completely occluded on the left side, so here we're coming from the right side. This is a triaxial system. So you have a guide here. You have another guide here. And this is actually selective injection in the venous phase and looking at all the veins that actually are filling. So this is it. The sinus starts somewhere around here. There's a cortical vein starts around here. So again, we thought that the pathology, all the feeding vessels are coming to that location. So we said, okay, we'll have to sacrifice that junction. And that's what we did. This is the coil mass into that segment. And interestingly enough, this is the ICA injection. This is not the ECA injection. This is the ICA injection. And you can see now all the veins are filling now in the normal venous phase. So you have immediately, you have a flow reversal in those cortical veins. So that's what we wanted to do and that's why we're able to do that. So a more complicated situation. So there's multiple feeders. This is external injection, multiple feeders from the internal maxillary, multiple feeders from the occipital artery, very large occipital artery. And you can see, the only thing that you can see actually is a bunch of veins over here, the sinus over here, and bunch of veins that goes all the way up. So this is actually a combined type three and type two fistula. You also have filling from the contralateral right side going all the way across the surface of the brain to the contralateral hemisphere. And to make things more complicated, you have also feeders that comes from the posterior circulation, everything coming all to the same location. This is just a skull x-ray. And all of those white thing that you see over here are just the bone remodeling where that actually, where all those feeding vessels are located. Selective injection through the internal maxillary, you can see there's a very large vein over here. So this is a combined type three and type two because you have a pathology at the sinus and you have a pathology at the veins themselves. So the treatment is just to try to disconnect all of those feeding vessels. And we're trying to do that with a combination of, you can see here, there's a bunch of coils into those feeding vessels, bunch of coils over here. And then to add on top of that, onyx, that the onyx kind of fill in between all of that thing. So, and ultimately you end up with some result like that that goes into the veins, goes into the feeding vessels, and ultimately sacrifice that junction of the sinus and pretty much block all the connections between the arterial system and the venous system. This is the venous outflow of the right hemisphere to the right side. This is the venous outflow of the left hemisphere to the right side. So we did not compromise the venous outflow in this particular patient by doing so. This is lateral injections at the end of the procedure. You can see how big the occipital arteries are. I mean, very, very large feeders. This is a illustration to show that. So the sinus is occluded below that. The feeders come from here, the feeders come from here. And this is all the pathology. And what you need to do is just block everything from the arterial system, from the vein, and complete the sacrifice of sinus as well. This is a patient who came in recently, three weeks ago with new onset seizure. He has a very small frontal hemorrhage. So he had an MRI and there's a bunch of vessels that they could see. They did an MRI in a smaller hospital in the suburbs. And what they're seeing here is a bunch of veins that you could see in the arterial phase. And you could see the sinus in the arterial phase. So just everything looks completely weird. So again, this is the MRV. And you could see that there's a missing sinus over here. This is a quantitative flow measurement for that particular patient. And you could see that the arterial flow, total arterial flow is 500 ccs. Venous outflow is about 1,000. So every single cc that comes into our arterial system should leave our venous system. If we're having more venous outflow as compared to arterial outflow, it means that there's some arteries that are contributing to intracranial circulation that are not part of the internals and the vertebrals. And this is part of the fistula. So about 400 ccs running on the venous system that comes from the fistula itself. This is the measurements, actually one of the draining veins. And this is about 100 ccs in one of the draining veins just filling in retrograde. So the angiogram for that, this is middle meningeal branches, middle meningeal branches, and you could see there's reversal of flow in these cortical veins. Severe venous hypertension. And this is actually an isolated sinus. So the whole sinus that transfers from here all the way down to the jugular valve is completely isolated. The pathology here is the level of the sinus. And this sinus is not a functional sinus. So the treatment for that, either you come and include every single feeding vessel or you go and sacrifice this sinus. Again, this is the vertebral injection. You could see all of those feeders that comes out of the jugular valve area. And if you want to know if this sinus is functional or not, look at the venous phase, normal venous phase for this patient. The right hemisphere drains to the left, the left hemisphere drains to the right. There's nothing which is draining down to the right side in the normal venous phase. So this sinus could be sacrificed. So we try to come back to this sinus transvenously from the internal jugular secluded, we know that. We try to come from the occipital artery, the smaller feeder vessels. So we went with a septal balloon through one of those ascending pharyngeal branches and we're injecting Onyx in there. And we're trying to get the Onyx to go all the way from the jugular valve all the way up into that segment of the sinus. So this is the segment of the trapped transverse sinus, sigmoid sinus down to the jugular valve. This is the gas at the end. This is the venous outflow of the right hemisphere at the end. We did not compromise that. We knew that the right hemisphere is not draining to the right side, so there's no change. But actually you start to see all of those veins that there were more congested and they were not seen before. So this is at the end, the cerebellar outflow. Again, not compromised. And this is the map at the end of the embolization. Again, remember, the venous outflow was about 1,000. Now the venous outflow about 600. So everything that comes now into the arterial phase goes out of the venous phase. So a few words about spinal dural fistula. When we talk about that, you have to know the anatomy of the intercostal arteries. That's kind of crucial thing. If you remember anything out of that, remember this. The intercostal arteries comes out of the aorta, which is in front of the vertebral body. They run around it. Often they run around it unsuperiorly. And ultimately they give intercostal arteries. And the level of the pathology here, it's in the dura sleeve that gets into the nerve root. That is the site of the pathology. So you have to remember that and you have to remember how to count those levels. So this is also an illustration of those intercostal arteries. And you can see here that, for example, this intercostal artery, it's coming from this location. So if you look at an x-ray, an angiogram for this, this might be, let's say, about the body of T6. But this is actually going all the way into the intercostal of T5. So this artery is not T6. Do not make that mistake of trying to localize intercostal arteries based on bony anatomy. This is not spine surgery. Those intercostal arteries are marked and named based on the intercostal rib that actually they run below that thing. This is an example of a patient who comes in and you have a lot of symptoms from venous hypertension. This is really extensive venous hypertension that goes all the way up and down. And this is selected angiography for this particular patient. Again, this is the catheter into this intercostal arteries. This is the rib of T6. That artery goes up. This is the rib of T5. This intercostal artery is not T6 intercostal artery. If you want to look at spine surgery, you would call it as a T6. This actually is a T5 intercostal artery. It goes up. It gives this intercostal artery. And if you want to know what is the pathology, this is the spinal canal. This is the lateral aspect on one side, on the other side. And this is the vein, which is really dilated over there. You have to also remember what is the level of the pedicle. So this is the pedicle on one side, the pedicle on the other side. And the pathology is actually over here. That's where actually the artery gets, becomes interdural. So this is the site of the pathology. So you get this intercostal artery, goes up, gives the rest of the intercostal artery. And then there's a direct connection that is actually interdural sleeve that runs with the nerve root, becomes interdural, and then goes in and have a junction with the vein, which is on the surface. So this is actually the site of the fistula. It's over here and it runs into that. So you have to make sure you disconnect that at that location. If you need to operate on this patient, you have to make sure that you're operating on the correct level. And the correct level is, this is the correct level, not below. So this is with a subtracted image. Again, this is the site of the fistula. This is the venous hypertension going up and down. You know, you're following that. You're following that severe venous hypertension. So when you look at a dilated vein, we don't know if this is being fed from a superior intercostal artery or all the way down from the middle sacral artery. So you have to do a complete spinal angio. The pathology could be at any point. If the patient have edema at the lower cord, it doesn't mean that the pathology at the lower cord. The pathology could be all the way at the T4 level and the symptoms all the way at the lower level. This is a patient who have embolization. So this is more of a working projection, oblique projection, selective with a micro catheter in place. This is the spinal canal, the spinal canal. And this is the component where it becomes intradural. So you have to block all of that. You have to make sure you disconnect this. And this is how it was before, and this is at the end of the procedure. So I'm gonna stop at this level. Thank you.

dural arteriovenous fistulas

classification

treatment options

embolization

surgery

spinal dural fistulas

intercostal artery anatomy