Complication Avoidance and Salvage Strategies in Aneurysm Surgery

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- Hello, colleagues and friends. And thank you for joining us for another session of the virtual operating room, from the neurosurgical access. Our guest today is Dr. Sepi Amin-Hanjani from University of Illinois, Chicago Sepi is truly an accomplished neurosurgeon, a very well-known open vascular and complex cranial surgeon. She's been a dear friend. We have been working together on the NNS board of directors, which has been an honor for me. Today She will talk to us about strategies and getting out of trouble in neurovascular surgery, an important topic. And I'm really honored to have you with us Sepi. So with that in mind, let's go ahead and listen to your talk and I'm very much looking forward to learning from you. Please proceed.

- All right. Thank you Aaron. And thank you for the invitation to be involved in this. I do wanna just take a moment to congratulate you on developing such a robust platform as you have for neurosurgical education. Not just nationally, but internationally. So it's a real pleasure to have a chance to participate in one of these sessions. So as you noted, what I thought I'd do is talk a little bit about complication avoidance and salvage strategies in aneurysm surgery. And these are I think, concepts that have been outlined in some of your prior webinars, but I wanted to add to that a little bit about concepts of flow measurement. Which I think are particularly germane and underutilized in aneurysm surgery as well. So with that in mind, let me get started with some of the concepts I wanna try and cover in the next hour or so. I have no relevant disclosures for this talk. I do wanna acknowledge a few people, particularly Fady Charbel. My current chair here at the University of Illinois at Chicago, as I talk particularly about the concepts of flow measurement. He's been one of the leaders and proponents of that field and really wanna acknowledge him for his contributions in that regard. And a few of our prior cerebrovascular fellows. Who've helped me with editing of some of the videos that I'm gonna show during this presentation. So really what I want us to start talking about first is the idea of what's really our goal and main challenge, when we're approaching aneurysms from an open vascular standpoint. 'Cause that's obviously my area background is open neurovascular. And our primary goal of course is complete obliteration of the aneurysm, while preserving parent vessels to avoid complications. And, you know, we have a variety of different aneurysms that we encounter, the most common, the most typical saccular aneurysms that we can address with primary clipping. And then getting to the more complex, less common aneurysms that are giant or fusiform and often require bypass strategies. And then of course there's the opportunities for more distal or fusiform aneurysm also to be treated with in situ bypass or anastomosis techniques. Now in all of these, there's a scenario where you wanna avoid the potential, shall we call them disasters. The complications that are gonna be most problematic or result in morbidity and mortality. And I think, the one that comes most quickly to mind for those people, is the idea of aneurysmal, uncontrolled bleeding or premature rupture, primarily with ruptured aneurysms that are going to the OR. I'll actually spend less time on this than what I consider to be a bit of the less considered disaster, which is lack of vessel patency. But I thought it was good to start with this because this is the one that comes to mind immediately when you think of a potential disaster in the OR with aneurysm cases. Now there's a lot of techniques that are well described for managing that situation, if it arises. And I'm just gonna highlight a couple of what I consider to be my own personal ideas about how these techniques can be applied in as preemptive a fashion as possible. You know, going back to Yasargil's descriptions of those, of course, the classic strategies are listed here. The idea of if you have a rupture, tamponade and suction right away, temporary clipping. I emphasize doing that under neuroprotection, particularly the idea of doing pilot clipping and temporary circulatory arrest. You know, with adenosine being kind of the new, a newer technique in the last decade or so for that purpose. So let's look at a case where some of those concepts come into play. This is a fairly recent case, I had of a young woman who has a small aneurysm you can see here. We debated this, but feel this is really an anterior choroidal artery aneurysm because of the course of the vessel coming from it. A posterior communicating artery is not visible, at least on the angiogram. I worry whenever I see such a small aneurysm and a young patient. These tend to be pseudoaneurysmal, very tiny, fragile, aneurysms with a very high risk of intraoperative rupture. So for my mindset, the complication avoidance starts preoperatively just with the notion of, "How likely is this patient "to have an intraoperative rapture?" And for this kind of aneurysm, I feel that it's quite likely. And so I wanna be thinking about all my strategies, very, very early on in order to be prepared for that. So for this kind of case, that entails the idea of doing anticipatory temporary clipping. Meaning not waiting till a rupture happens. So just to walk through this surgery a little bit, here, we're exposing the supraclinoic carotid. First of all, it becomes evident that the clinoid is preventing easy access to approximal clipping. So the first strategy here is to ensure that that proximal exposure to the carotid is obtained early on and a bit of clinoid drilling was done for that purpose. And here are the temporary clip has been put on already in an anticipatory fashion, even before dissecting. Knowing that there is cross-flow across the A1. So there's not an area of dense ischemia. And as you see, very early on a rupture starts to happen. And in an anticipatory fashion, there was already a cotton ball there, ready because I was anticipating a rupture would happen. And once it does, as it did in this case, the fact that there's a temporary clip on the supraclinoic carotid, allows that to be less disastrous while a temporary clip is put on the A1, in this situation, to keep the field from becoming too crowded with temporary clips. putting a clip on the proximal ICA, putting a clip on the A1, really slows down the bleeding. And then that cotton ball with Tamponade and suction, can be utilized to try and find the source of where the hemorrhage is coming from. And you see even there, needing to move the clips out of the field to make sure the field isn't crowded. I think one of the mistakes I used to make early in my career was to rush, to put a clip on right away and then realizing over time that it's better to take a few moments to dissect out the anatomy, to make sure the clip isn't put across a vessel like the choroidal and cause compromise. So here we can see the Choroidal itself. The third nerve is gonna come into view there. And once the site of bleeding and the aneurysm has been dissected, placing a mini clip to occlude that, and then a buttress clip on this very small aneurysm so that the initial clip can be advanced even further. And during this time SSEPs and MEPs are being monitored. So you have a sense of how long you have with the temporary clipping, so to speak. And the temporary clips can then be removed once the rupture is controlled. So I think this kind of case just highlights how it's much easier if you anticipate that the rupture is gonna happen. To have already had a temporary clip in place, already have the cotton ball ready to go, and then be able to handle that rupture, in less time essentially by being able to get it under control, fairly quickly. So and there's the ICG, just showing patency of that anterior choroidal, the clip in place, looking for the perforators, making sure nothing's been compromised, during that clipping 'cause unfortunately I think with intraopt rupture, the primary concern is the rush to get the bleeding under control, often can lead to injury or occlusion of perforators or other vessels. And again, that temporary clipping and controlling the bleeding to be able to visualize becomes very important. So here's the postoperative angiogram. You'll see the patient is in spasm, about seven days postop, but thankfully was asymptomatic from that and recovered quite nicely from her subarachnoid hemorrhage. So just an example of how to manage an intraoperative rupture with some of those techniques. The other technique I wanna highlight in this case, which was a 68 year old male who presented with a larger Pcom aneurysm, no angiogram was done because he needed to be taken to the operating room quickly for temporal lobe hematoma that was associated with this aneurysm. But this is an opportunity to show one of the techniques that I really, really like to use in ruptured aneurysms, which is the concept of pilot clipping. And as you'll see on this particular case, proximal control is again being attained. There's a clip being sized up here on the carotid that you can see how there's a lot of atheroma in this carotid, all the way here. And so this is not an ideal case for that concept of anticipatory temporary clipping. In fact, this is the kind of case where I'd like to avoid putting temporary clips on that carotid altogether because of the degree of atheroma and that the injury that might occur even from the temporary clipping itself. So I think this is a good case for doing a pilot clipping strategy. Which I think of as basically being a temporary clip, but on the aneurysm itself. And because this is a larger aneurysm, there's plenty of ability to work just at the neck of the aneurysm. Here we're seeing the distal neck being explored there. We're seeing the Pcom itself traveling there and the perforators clearing those. And all of that is to basically clear a path, not for an ultimate clipping, but just for an initial pilot clipping that will then allow dissection of the whole aneurysm and a more robust, permanent clipping. I'll just point out here that you'll notice I'm using a fenestrated clip, even though there's nothing that the fenestration is really going around. The purpose of that is for these atherosclerotic aneurysms in particular, I find that fenestrated clips are more effective because of their higher closing pressure across the entire blade as opposed to a straight clamp itself. Now with that pilot clip in place, the entire aneurysm dome can be mobilized and dissected. You see the aneurysm has been deflated now the rupture site cannot be identify. So it's a version of being able to manipulate the aneurysm without putting temporary clips on the parent vessels. Now that initial pilot clip is being removed, and another pilot clip has been played most, more distally just to control the rupture site. And this gives all the time in the world to be able to really dissect the aneurysm. Fine, there's a bit of residual aneurysm there, requires another different kind of clipping strategy, a little more dissection done. Now, a curved clip that's being placed around that remaining remnant, keeping in mind that there's a lot of atheroma in here that requires again, multiple clips to deflate the aneurysm and keeping the Pcom out of the clip as that's being done. And again, that avoids the need for temporary clipping while controlling the risk for any rupture, because the rupture side of the aneurysms already been controlled. And here's the final ICG, Just showing the clipping. You can see how the atheroma there prevents the ICG from being visualized. So I think that's a particularly useful strategy and here's the, the postop angiogram from that particular case. So I think those just highlight kind of a couple of additional nuances to the idea of how to control, for that intraop rupture disaster. But as I said, what I really wanna focus a little bit more on is the disaster that that's, you know, often not thought about as much as a disaster, but is often the more frequent problem or complement complication from both ruptured and unruptured aneurysm surgery, which is a vessel compromise or an occlusion. And that can happen for a number of reasons. You can have intrinsic compromise from atheroma, That last case I showed is a good example of how patients with aneurysms often have atheromatous disease within the vessels or their aneurysms, or if it's a larger aneurysm thrombus. The clips themselves can cause compression and the occlusion of branch vessels or perforators, where there are times when manipulation of the aneurysm or the type of aneurysm unexpectedly arises in the need for vessel occlusion, intraoperatively, that hadn't been anticipated before. And what are our strategies to deal with those kinds of problems? Of course, there's different clipping techniques and I'll show a couple of examples of that. And there's sometimes a need for revascularization to avoid this problem of a vessel compromise and stroke. That would be a consequence of that. So again, this is not an infrequent problem. If you look in the literature, anywhere up to 30% of cases, probably that's a high estimate, probably more in the range of five to 10%, but reported as high as 30% of cases can result in some kind of unexpected vessel compromise and not all of those cases will result in a problem, but a good proportion will. So I think it's a scenario where it's useful to be using all the tools at our disposal to optimize the outcome and avoid that very preventable complication. So of course intraop angio video, ICG angiography are useful tools for that. And I'll highlight and talk a little bit particularly about intraoperative flow measurements, because I think that's relatively underutilized and a very useful tool, as well as something that I've adopted in the last decade or so, much more frequently is using neuro-monitoring intraoperatively, to help see if there's an indication of a physiologic compromise. So what are our kind of existing popular methods? I think all of you are well familiar with of course, visual inspection. I mean, that's why we do these cases under operative microscopy so that we can see if there's vessels being compromised. But as I pointed out, the literature indicates that that can be inaccurate in a good number of cases. Intraop angiogram can be very helpful for this, both in demonstrating obliteration of an aneurysm as well as patency of the vessels, but it's a bit time consuming. There's some costs and the, you know, needing the endovascular expertise, which of course dual-trained individuals have. But for someone like myself, bringing an angiographer to the suite to do that end drop of angiogram can be time-consuming. Doppler's a fairly easy tool to use, but it's quite qualitative and subjective. Sometimes it's not as good for diagnosing stenosis in a vessel versus an actual occlusion. And then as I mentioned, electrophysiologic monitoring can be quite labor intensive and costly as well, depending on the environment one is in and there can be false negatives or false positives. So it's not a perfect tool either. And ICG of course, I think is now routinely used and, is an excellent technique for looking at perforators. But we have to keep in mind that it is limited to the field of view that you can see through your microscope. So if something's behind a structure, you're not gonna see it. And the idea of repeatability, you know, once you've given a dose or so. And Aaron, I know of course it's not about forcing angiography and other modes other than ICG. And all of these are incrementally, I think, improving the tools for this, but there are still some limitations on what you can achieve with these, fluorescent dye angiographies. And so the tool that I'll highlight particularly is this ultrasonic flow probe, which is another way of assessing patency of vessels, really not perforators, but larger vessels. And the advantage of it is that it's quantitative and repeatable. I think those are the two main advantages of it. The main disadvantage being that it does require some additional dissection of the vessels to use a probe, that essentially has to surround the vessel partially in order to get an accurate flow measurement. And again, we'll look at some examples of, use of this in aneurysm surgery. Now, the concept behind the flow measurements and aneurysm surgery is pretty simple. The idea is that, you know, if you're dissecting or working on an aneurysm, you dissect the relevant vessels and measure the flow in distal branches. And so in this case, for example, a more proximal carotid aneurysm measuring flow in the MCA and the A1, would give you a baseline. And then after clipping, it would be a matter of remeasuring the flow. And for example, in this kind of case, a Doppler would not show a particular problem perhaps, it would show that there is flow there. But a quantitative measurement may well show that the flow is present, but significantly diminished in this case say reduced by 50%, which really suggests that there's a significant stenosis going on. And then that allows repositioning of the clip. And in this example, you'll see that the subsequent measurement is actually higher than the baseline. Well, why is that? Well, it turns out that as you might expect after a period of relative ischemia, there can be hyperperfusion. So for a little period of time, the flow will actually increase. And then will stabilize again after about five or 10 minutes or so. And that's just highlighting that point. I think the other important factor to keep in mind is like with everything, the technique is only as good as controlling the conditions in which it is performed. Meaning that flow in vessels is altered by other factors, such as anesthetic and tidal CO2 blood pressure. So all those variables need to be kept constant, between baseline and post clipping measurements in order for those flows to be really reliable in indicating that a stenosis is at play so to speak. So here's just kind of walking through how this technique can be applied because often the question becomes, well, "How difficult is it "to get these flow measurements, "especially in aneurysms where you don't have as easy access to all the distal vessels?" And I think this is a really good example of that. This is a patient with a ruptured aneurysm with a somewhat complex Acom aneurysm here, and here's some graphics and a video to show how this low technique was applied to this particular case. So, this is being approached from the right side. It's a right dominant A1 with a smaller left A1, both A1s have already been exposed. And here, this here is the right A2 that's being exposed here. And the posterior aspect of the aneurysm, looking for a dissection of the neck, you can see that the neck of the aneurism is really coming off the right A1-A2 junction, as well as the Acom itself. Here are the perforators there in the back of the Acom that need to be preserved through the aneurysm, I'm dissecting those off the perforators, just getting ready for a potential clipping. And before getting too far, where there might be a risk of a rupture intraop from this ruptured aneurysm. The first step is just measuring the flow with the flow probe. As you see, it needs to sit around the vessel, cup the vessel essentially, measuring the flow in the A1. And because what we're really interested in is the flow in the A2s. We can indirectly measure that by putting a temporary clip on the contralateral A1. Now all the flow to the A2s is coming from the ipsilateral right-sided A1. And once we measure that flow, that tells us in this case, that's about 85 CCs as you can see here, that tells us that each A2 carries about 40 CCs or so, 'cause the A2s tend to be co-dominant, pretty much are equal in flow. So keeping that in mind. Next step here was okay, let's do a clipping. You'll see that I have a temporary clip here on the contralateral A1. That again, is this anticipatory temporary clipping that's the temporary clip that would be harder to get on if there were suddenly a rupture. So that's already in place the ipsilateral A1. I don't have a temporary clip because I don't wanna suffer any ischemia time from that. And this initial clipping strategy was a fenestrated clip. Fenestration around the ipsilateral A1 here. You can see that on the schematic here. The problem with that was once we measured the flow, the flow in the A2 had dropped dramatically to about 10 CCs and we knew it was supposed to be about 40 CCs. And that's because the atheroma at the base of the aneurysm was being pinched in this fenestration, including the clip. And that gave us an indication of needing to change the clipping strategy. So if we now go to the next step, which is to be able to modulate the clipping and the importance of this is with an aneurysm like this with some atheroma at its base here is that you need to clip reconstruct this in a way that's not gonna occlude the branches. So instead of a straight fenestrated clip, an angled fenestrated clip is being used. The fenestration is actually going around the atheroma. So it will not occlude this A2 branch that's coming out, and sparing the contralateral A2. You'll notice there's a little mini clip on the rupture site of the aneurysm. Again, that concept of essentially a pilot clipping on that. And once that first clip has been applied, the next step is measuring blood flow to make sure it hasn't already compromised the flow. Then additional clips can be applied. And after each clip you can measure the blood flow in the A2 to make sure that each additional clip and here's the final clipping strategy on the schematic here that you can compare to what's going on here, demonstrates that the flow in that A2 is preserved. And ultimately was, again, we said baseline was about 40, that we surmised indirectly and is measuring 35 at the end And as a final step, because it's hard for us to measure the contralateral A2, it's really out of range for the flow probe. We can remeasure the A1 flow as we're doing here and make sure that it's similar to what it was at baseline with a temporary clip on the left A1 And in fact it was ADCCs, it was 85 at baseline. Here's our ICG. Now I'll point out that I think the combination is very powerful because you need the ICG to look at your perforators, but the flow measurements allow you to do repeated measurements as you're doing more complex clip reconstructions on these kinds of aneurysms. So here's the postoperative angiogram that shows the clipping strategy, here and the aneurysm obliterated. So that just gives you a kind of an example of how that can be used. Is this kind of strategy useful at all? Does it alter our intraoperative plans? Do we actually avoid vessel compromise? We had looked at this a while back when I initially came to UIC and looked at a little over a hundred cases and we found that in fact, in about a third of them, about 30 cases, you would see some degree of flow drop after clipping, that you could reverse, by readjustment of clip. Importantly, though, you were also able on some cases to avoid clip when it comes to readjustment, by measuring flow. Sometimes things visually look like they're kinked or problematic, but they're not, and you don't actually have to adjust the clip. And in a few cases, we were able to trap aneurysm safely by measuring distal flow showing there was enough collateral. And in this series with that strategy, at least we didn't see any unexpected strokes on CT scan. So I think this data at least helped affirm our impression that flow measurements were useful. So I'll give another couple of examples of how the types of cases where I think this kind of measurement really comes into play. And again, a lot of these are cases where we're dealing with diseased vessels, patients with atheroma, which can really be, a silent problem so to speak. Where the external visualization does not reveal what's going on on the inside of the blood vessels and can therefore be a real risk for vessel compromise. So here's a larger MCA aneurysm. You can kinda get a sense from the 3D angio that the vessels are somewhat irregular and you already anticipate there's probably gonna be some atheromatous disease here. Here's the Sylvian fissure being opened up dissecting and you can see all this atheroma, already in the dome of the vessel and atheroma there in the M1 as well. And, you know, dissecting the aneurysm kind of the usual maneuvers to free up the MCA branches there. And really with such a degree of atheroma in these vessels, this kind of aneurysms, are well-suited for a tandem clipping strategy. But before getting started with that, the first step is measuring the blood flow. Because again, with atheroma present, there's really just gonna be a high chance of that atheromatous disease causing an internal compromise of the vessel lumen and potentially causing a compromise of a branch. Now with the larger aneurysm, I found a relatively atheroma-free spot on the M1, just to reduce the turgor in the aneurysm. And again, using a fenestrated clip, not because of the need for the fenestration, but because of the higher closing force, along the entire blade to really squeeze this dome closed with this thick atheroma and doing this kind of tandem clipping. But the real danger is that again, atheroma, maybe getting pushed into the base of the aneurysm. And in this kind of case, it becomes particularly useful to be able to continuously after each clip is applied, measure flow in each of those MCA branches. So you see that being done here, measuring flow in the MCA. And if the flow is dropped, backing the clips up a bit and they can be literally micro-motions of a clip can make all the difference in some of these cases. Literally sub milli-metric backing off of a clip can resume the flow because that advancement of the clip has just caused a bit too much compromise on the atheroma itself. And again, I don't know of any other intraoperative strategy, certainly intraop angio, ICG, et cetera, that would allow you to do this in such a repetitive fashion to reconstruct an aneurysm like that. And here additional clips are being applied along the base and really trying to reconstruct the entire base of that aneurysm so that the aneurysms as best occluded as it can be fully occluded, but preserving the branches. And the ultimate measurement comes from... here's the base of the aneurysm reconstructed, you see all that atheroma at the base and really without the flow measurements to confirm that the flow, is being preserved, visual inspection alone cannot confirm that. And I can tell you that over and over again, there's been cases where I thought the clipping looked great, and I've measured the flow, and there's no flow in the branch. Because what you see externally, does not reflect necessarily what's going on on the internal lumen there. So ultimately this tool, again, it's very fast. You just put the probe on the vessel, you're able to get a flow measurement, within 10-15 seconds and quickly readjust the clip as necessary. And again, at the final clipping, once the flows look stable, doing the ICG to look at perforators and look at the branches again, as a confirmatory, that there hasn't been any problem that's been created by doing that. So this next slide will show us the postoperative view of that. And you can kind of see this tandem clipping strategy and how the branches have been preserved there. And I think that would have been very difficult to do with what I would call otherwise kind of a blind clipping, blind in that you're blind to the actual flow and the vessel branches itself. Here's another case, a posterior circulation, aneurysm, where we see a really kind of a similar situation. This aneurism you can see is got really a PICA with an aneurysm that's quite broad based. This is being approached through a far lateral approach here. You see the brainstem, upper cervical spinal cord there, here's the cerebellum here. Here's the vertebral artery. You see the rootlets of the 12th nerve and you see the lower cranial nerves here. And now we see the loop of the PICA as it's looping under the lower cranial nerves. And as I'm, dissecting towards the origin of that, the aneurysm will come into view between those rootlets. And here you see the base of the takeoff of the PICA and the aneurysm there. And initially this looks like a pretty straightforward clipping and actually quite a straightforward trajectory. But the first step again is just measuring that blood flow in the PICA vessel itself. So you have a good baseline that can be compared to after clipping, after the dissection of that PICA branch, really, it becomes a matter of defining the full neck of the aneurysm. And again, you see the vertebral artery, curving down here just as it kind of curves on this angiogram. And it looks really favorable for just a straight clip to go across the base of it, just making sure that any perforators are preserved. Typically in these kinds of locations, just to keep the perforators or rootlets of nerves out of the way. I like to put a little rubber dam that kind of protects those and moves that out the way, I find that a little bit less abrasive than using cottonoids, which can sometimes get caught on finer structures. So there's a rubber dam being put in for that purpose. Just to reduce again, the turgor in the aneurysm during the clipping. Cause there's some atheroma there that's a temporary clip that's going on the vertebral artery. And again, here is the neck of the aneurysm. It seems like a really kind of a straight shot, easy just straight clip across that base. But again, you'll notice there's some atheroma here and atheroma, you know, is really always the challenge in these situations because even if the clip can go on straight, the atheroma itself can push the clip in one direction or the other, often pushing it towards the takeoff of a vessel and causing an occlusion that may not be as visually obvious. So as you see, the clip goes on, it's tended to get pushed a little bit down towards that PICA origin. Visually, it looked not bad, but really what revealed that it was a problem, was the flow measurement. The flow measurement had gone down dramatically. PICA flows are usually somewhere about 10 to 15 CC range, and that had dropped a two or three CC. So here the clipping removed, trying to readjust it, but really the atheroma is preventing the, you see that lip of atheroma there is preventing the clip from being adjusted higher up. So these are scenarios where you really then have to, again, change the clipping strategy. So in this particular case, the idea was, well, we need to preserve the PICA origin there. And in order to do that, this is a side-biting fenestrated clip. The fenestration is being placed around the take-off of the PICA aneurysm, after it was placed, confirming that the flow is not compromised. And then sequentially adding clips and measuring with each clip addition, if it's affecting the blood flow or not. And in that fashion, being able to gradually obliterate the entire aneurysm right up to the origin of the PICA. So you see this as a more complex flipping strategy. Two fenestrated clips, and then add many clips through a fenestration to get a final result where the flow is maintained, but the aneurism is also occluded successfully. Which is the ultimate goal. And especially for unruptured aneurysms, you know, the patients are coming in neurologically normal and without a problem, you know, the goal is to obliterate the aneurysm and certainly not give them any new deficit of any kind. So it's, I think really imperative to be able to obliterate the aneurysm and preserve vessels. So here's, again the preop here, you see again on the postop, how that PICA is essentially reconstructed with that clip strategy, which I think would have been very difficult to do, to get a complete occlusion and a reconstruction without the aid of intraoperative tools like that. So, I think for complex aneurysms, it helps us, these flow measures really help us measure the flow in the vessels. If we're needing to revascularize measuring the flow in the donors vessels and the completed bypass, also becomes very helpful as well. And it's a strategy then that can be used not just for clipping, but for revascularization as well. Here's an example of a case, again, with a subarachnoid hemorrhage and what looks to be a fairly, you know, clippable straightforward, perhaps MCA aneurysm, again, a little bit smaller. I always say the danger is in the smaller aneurysms. These ones are the ones that are trickier to deal with. So kind of bringing together some of these strategies of dealing with vessel complications. Here's an example of this case that looked fairly straightforward, but during dissection for proximal control, there's an intraop rupture that happens. You can see it right there, and it's, you know, that part can be controlled with temporary clip, with tamponade, all the same strategies as we talked about earlier can be applied and the aneurysm itself can be... The intraop rupture part of the disaster can be controlled. The problem is that sometimes what you're left with, if we go to the next slide is, a problem with vessel occlusion. So this was a case where the rupture had happened at the neck of the aneurysm. And in that happening had resulted in a tear as we're seeing again there, right at the very neck of the aneurysm and controlling that with a clip really was resulting in occlusion of the vessel itself. And again, the flow measurement showed us that that vessel was completely occluded, but there's not a good strategy for replacing clips and controlling the rupture. So again, if we go to the next slide, we have to think about salvage strategies in that scenario. And when there's no option for another clipping strategy, the salvage becomes a revascularization. Now, typically in that scenario, we're thinking about ECE-IC options. An STA MCA bypass would obviously be the fastest and easiest for an unexpected situation. But unfortunately I would say that the superficial temporal artery is typically not a good choice in the setting of subarachnoids hemorrhage. And that's primarily because once the patient gets into a period of vasospasm trying to treat that, here's an example of an STA graft in a patient who then developed vasospasm, trying to treat that, especially with our most useful types of treatments, like endovascular treatment, becomes quite hard because you get spasm in the STA itself with use of pressers. And certainly it becomes very hard to navigate any catheters to administer endovascular therapy. So our experience has taught us, that STA graphs are not a great option and subarachnoid hemorrhage EC-IC vein grafts are particularly favorable in that situation. Here's an example of one that was performed for a ruptured aneurysm that required MCA occlusion. And you can actually treat vasospasm through that. You can see a catheter there. But unfortunately that requires you to really have thought through the need for the graft, you know, have a vein prepared, et cetera. So it's really often not a viable option in the moment when something unexpected has happened. And I think in those unexpected situations, like the case I just showed, intercranial bypass options become really much more useful. And the idea in this situation would be to think about using an in situ vessel like the temporal artery or a side-to-side type of a bypass situation. So that's what was done in this case, because fortuitously, as you can see from the angio, the M2 branches come quite close to each other, more distal in the Sylvian fissure. And because of that, they could be aligned and brought together. Here's one temporary clip on the proximal vessels, two temporary clips on the distal vessels and a side-to-side anastomosis that was run in the back wall first, then the front wall. And that's probably the quickest strategy to revascularize. And then the flow measurement confirms if that's been successful. That both branches still have adequate flow in them. And you can see the clipping, that's more proximal on the fissure there. So thankfully that showed that the flow was restored in that branch by doing that salvage maneuver. And here's the postoperative angiogram, where again, you see the anastomosis more distally, you see the clipping there and that's, I think an important backup salvage maneuver when something unexpected like that happens. Here's another case, where some salvage strategies were needed, but in a different way. So here's another subarachnoid hemorrhage, very large MCA aneurysm here. The neck itself doesn't look too broad, but again, with these large aneurysms, what you typically then encounter intraoperatively is a lot of atheroma and potentially thrombus, even within the aneurysm. So, one goes into these cases again, with a mindset that the clipping is gonna be more of a complex clipping strategy, despite any appearance that it may be a relatively narrow neck aneurysm. So here's another scenario where there was some bleeding and an opportunity to just show how that was handled. So here again, there was some anticipatory temporary clipping, mostly to really deflate the aneurysm. And the goal was to try and attempt a tandem clipping strategy again, and you see how large the aneurysm is compared to the branches that are arising from it. And boy, just in the manipulation of that, a small hair happens right at the neck or the base of the M2 branch there. And it's not bleeding a lot cause it's a small area of rupture, but nonetheless, that's a tough situation to handle. And here is where a strategy that Dan Barrow and Robert Spetzler, wrote up and popularized, of using a little bit of cotton to control a rupture right at the neck of the aneurysm was just, was really save the day so to speak. So if we show that strategy being used here, again, not a lot of bleeding because there's a temporary clip in place. Here's the cotton, putting that right at the junction where that bleeding is occurring and then using some tandem clips to buttress the cotton against the bleeding site and just control that situation quickly enough that temporary clips can be removed to revascularize the distal territory. Cause really the only other option would be to do a revascularization with a bypass. And that's gonna take a longer period of time while there's potentially an active rupture happening. So, that I think is another useful tool in these situations, to utilize. The next problem that arose, Unfortunately, if we run this particular scenario, Is because this is such a large aneurysm and because these tandem clipping strategies, require so many clips, just the weight of the clips as they dropped, was causing the flow to kink. And we could measure the flow , as we let the aneurysm clips fall or raise them and see that the flow would go and come back and go and come back, just by the way of these aneurysm clips. And so that led to an idea of, well, "Now we have to abandon, "perhaps revascularize both branches "with bypasses, get rid of all these clips." But one of our fellows at the time, Tarek Rayan, came up with the idea of, well, "What if we buttress those clips in a position "where it didn't affect the flow?" And using kind of a version of what's been described for retracting vessels with slings, for example, we used a technique of suture retraction while measuring blood flow to buttress those clips away from the branch and preserve the flow in the vessel using this kind of clip retraction technique. Which actually turned out to work very nicely if we play this video. But again, I think, it would just not have been possible if we weren't able to confirm patency in real time by flow measurement. So, here's a suture being placed, rather than tying it to the dura. We're clipping it so that we can adjust the tension, until blood flow is preserved. And there's the junction of the aneurysm to the distal vessel. And once we confirm the flow is adequate, making sure the dura was well sealed and using the bone flap to really, push it up against the sphenoid bridge there so that we could maintain the position of those clips. And with doing that, here you see the ultimate clipping strategy, Lots and lots of clips there. She has a vasospasm on her postop angio, but vessels are preserved and the aneurysm's completely obliterated. So just another way to salvage that situation, fairly quickly without having to go to a more complex bypass strategy in that situation. And here as a final case. I just wanna show a case that's a little bit of a different thought process. I think we think mostly of disasters as happening intraoperatively and so that we have to then salvage or avoid complications during surgery. But I think sometimes it's helpful to think about these more complex cases in the scenario of avoiding ever getting into the problem so to speak, kind of a preemptive before you even get to the OR, to doing something differently than you might otherwise. So, here's a case that I think really highlights that well. This was a patient who'd had a prior history of subarachnoid hemorrhage had, had prior craniotomies many years ago. I think you can see these wires there as a good evidence of how that being a much longer time ago. And it has already craniotomies for a basilar tip clipping, a Pcom. So bilateral craniotomies has had a suboccipital for a PICA clipping and now is presenting with recurrence of the basilar tip aneurysm. So I think in every scenario as a surgeon, and it's not even a favorable basilar aneurysm is posteriorly pointing, previously clipped, in someone who's had multiple surgeries. Of course, this is a case where endovascular therapy would be the ideal scenario for treating a growing aneurysm in someone in this situation. However, sometimes the endovascular therapies are limited by certain anatomic features. This patient had a lot of vascular tortuosity. And even though coiling with stenting was the strategy we wanted to pursue, access was limited because of the tortuosity of the vertebrals. And you know, the other idea of going trans-circulation through the carotid, through the Pcom was not possible because she didn't have accessible Pcom So you are left with the scenario of considering going into a very high morbidity reoperation, which is what I would call a disaster in the making, where you feel like you're backed into a corner. That's the only option you can offer, versus doing nothing, and hoping that she won't rupture, from this growing aneurysm, despite her high-risk fissures of prior subarachnoid hemorrhage despite it being poster circulation, et cetera. So this is kind of a scenario where I think the salvage is before the disaster happens. And that's kind of thinking outside the box that if we think endovascular is our best strategy and the problem for that is an access problem, then dealing with that problem with a surgical solution, that's a lower morbidity surgical solution. In this scenario, it was the idea of creating a new conduit through which the endovascular therapy could be more easily and effectively done, creating a carotid-vertebral bypass. And this as an extracranial operation is fairly straightforward and much lower morbidity than attempting to do an intracranial bypass. I'm sorry, an intracranial, basiler artery clipping strategy. So what this really entails is an incision similar to what would be done for a carotid, that's familiar territory to us. Exposing then the vertebral artery between C1 and C2. Maybe not as familiar to us, but again, the kind of dissection that's not so, it's not so difficult. And some techniques that allow us to get access to the vertebral artery, which tends to have a good kind of redundant portion that's C1 C2, and then moving on to doing a, typically a vein graph between the common carotid and the vertebral artery. All an extra cranial cervical operation. And here's just a short video of this. This is something we published a few years ago, the longer versions of it is online with the article, if anyone's interested in that. But here's that vertebral artery here in this case, this vertebral artery was end-to-end anastomosis with a vein graft. It can also be done as an end-to-side anastomosis. Here you see the end-to-end anastomosis, being complete there on the vertebral artery. And then the vein graph down to the common carotid in this case, which is again, very familiar territory to us, you know, similar to when you're sewing up a carotid endarterectomy, for example. And once that graft is in place, then the idea of flow measurements, confirms that the graft is functioning properly and functioning well. And here you see the carotid artery, the graft, here's the jugular, the graft is just laying over that and that conduit. Then once it's healed over the first few weeks or so, it can be used as is a very robust conduit. If we go to the next slide that really, as you see it angiographically here, here's that graft heading into the vertebral artery. That becomes a completely straight shot for endovascular therapy. And allowed a very successful stent coiling. Now, you know, there have been published reports of people just doing direct sticks or exposures of the vartebral for the treatment, the advantage of having this conduit a more permanent conduit for this is as we know, stents and coils and whatnot, there is a, you know, 10-15% chance of recanalization over time. With this graft in place, treatment can be repeated in subsequent sessions as necessary if there's recanalization. So it becomes basically a permanent access conduit. And I think that's the advantage that it provides in that kind of scenario. So as final thoughts, I would say, really, we just got to be keeping in mind our ultimate goal in open aneurysm surgery is that really we do wanna, completely obliterate the aneurysm. That is one of the real potential advantages of open surgery still, is that we have a greater opportunity for complete durable obliteration, compared to endovascular strategies that are still ranging sometimes in the 80% range or so. But at the same time, that has to be done with the preservation of current vessel. So with very little morbidity, and I think the idea of recognizing that there are tools like flow measurements that are helpful in identifying if you even need a salvage strategy. Because you don't wanna find out postoperatively a vessel's occluded or a stroke has already happened. It's just yet another tool in the overall toolbox that we have as surgeons that we can use to help avert complications. So I'll stop there, Aaron, and yeah, if there's anything you want me, to discuss or turn back to, I'd be happy to do that.

- Sepi, I really enjoyed the videos, really spectacular technique, great expertise. I really love the way you handle the tissues. You avoid unnecessary traction, you protect every normal structure. You have a very thoughtful methodology in managing complications and those anticipation moves that are so critical in terms of avoiding complications. It's always been my experience, which I'm sure you probably agree is that it's not often the complication itself, that leads to a poor outcome, but it's more of a poor reaction or the uncalculated reaction of the surgeon that leads to the poor outcome, managing that complication. Often, you know, when the bleeding comes in, the surgeon may not be prepared. They all worried about controlling the breathing, not protecting the vessels. And that can be really devastating, as I'm sure we all know. So I wanna really thank you for absolutely superb expertise and the videos. I think the flow is so important that you mentioned, I'm sure all of us have those moments. If we're not using the flow measurement that you're doing an MCA aneurysm, the flow looked pretty good on ultrasound and the patient wakes up with a distal MCA stroke. It's not that the flow was there or not. It's not qualitative. It's the issue of quantitative. I think that's what we should really emphasize. And remember that it's not yes or no. It's about how much, is it enough, to maintain irrigation into these stalled territories. with that in mind, I wanna ask you a question that we all face everyday Sepi. And what is the future of neurovascular surgery? There is such immense advancement with intrasulcular devices, flow diversion, even MCA aneurysm have become very much amenable to treatment with endovascular intrasulcular techniques. Could you tell us where we're going? I think there is an idea that there is a few of neurosurgeons that are pushing the limits inappropriately for surgical techniques. And definitely you're not one of them. And I feel like still we have just clip aneurysms because we wanna prove a point. I don't think that's appropriate. We should do what's right. If it was us as the patient. And then based on that, make a decision. There is no doubt, endovascular methods are less risky, they protect neural function more, the outcomes are better. There's some question about durability, but even that has been proven now to be a hundred percent a problem because of retreatment. So as a neurosurgeon, today, if you and I, God forbid, have a Pcom aneurysm or a PICA aneurysm, and they say, well, we can stent it and coil it. I would say most of us would say, well, if they can do a good job, let's go ahead with endovascular technique. But there are occasional instances when, end surgery still has a role. So considering you and I, as the patient carrying an aneurysm, what do you think is a rational and practical strategy for aneurysm treatment in 2021 and onward?

- Yeah, I mean, I think you hit all, the germane points on the head there. So, we're in a scenario where the advancements in endovascular technologies continue to allow more complex aneurysms. We hope to be treated with endovascular strategies. I think we have to be honest in the appraisal of those outcomes as well though. And keep a close eye on those because we do see sometimes an over adoption that results then in a cadre of outcomes that aren't as ideal, shall we say, or often more on the endovascular front, and those are the cases that then become very challenging on how to deal with surgically, right? Once they've been treated endovascularly and you have to now come up with a surgical solution potentially because the aneurysm's growing or it's giant or it's causing a neurological deficit. And so, it is becoming more and more of a scenario where surgically what's required of open techniques is to deal with more complex, more and more complex types of vascular lesions in an environment where the concern, I think for the future is that the expertise will whittle, right? Because the volume is not there of the more simple and therefore how are you gonna train people to deal with the more complex? And I don't have an answer for that, other than I think from a kind of systems basis, my view would be that, you have to invest, and this just may not ever be feasible in the healthcare setting, in the US, but to invest in a strategy that understands the importance of centralizing those types of treatments. It sounds like we have another opinion.

- Yeah. We have a third opinion here. You know, I agree with you completely Sepi that the issue of managing more difficult cases and expertise in fact is decreasing.

- I think one of the strategies that, you know, if it could be, if one could kind of imagine the ideal set up of delivery of care for vascular disease, it would be a model of centralization because the diseases are in a relative sense, fairly rare. So the idea of centralization to centers where what I would envision dual-trained individuals are working in groups and in those groups, those dual-trained individuals, develop specific expertise. And that expertise could be, you know, to have the very high-end endovascular who also does some open vascular that's not as complex, versus having individuals who do the very complex, including bypass, et cetera, for vascular lesions, but can also do the basic endovascular and, you know, kind of advance the manpower for, and woman power for things like stroke thrombectomy, which is necessary too. So the idea of having sub-specialization within larger groups of dual-trained individuals at centers where the volume was being centralized, that kind of addresses that issue of there's not enough for someone to gain the expertise in that. So to me, that would be potentially the way it really needs to be, to ensure the expertise is maintained. And then I think on top of it, it's really the adoption of these kinds of tools that make it so that you don't have to have done a hundred cases of an MCA aneurysm to understand how to preserve vessels, because you've just figured it out by looking at it, right? Like you're using these other tools like angio and ICG and flow measurements and all of those things to make the learning curve faster, alright. Or to get, at least get your outcomes to be better and faster than just purely well, "It's because I've done, "several hundred of these, "I now know how to do it properly." It's to get that to be a smaller and smaller and smaller cadre of cases before you get to that level of proficiency by kind of using these tools.

- I think that makes very good sense. I think ideally we like to have centers of excellence and focus there, but as you know, in the United States, there is fair number of financial incentives that control how the cases are distributed and the hospitals control that fair amount and the physicians or surgeons are not that much in control. So in reality, I think, would be unfortunately different than what we would love to see, which would be right. Which I completely agree with you. I think that's number one. And I think number two, there are so many of our neurology colleagues and even I've seen a cardiologist treating aneurysms endovascularly, which obviously complicates the centralization of the care further. I would say that, we are most likely heading to an era where most end of the treatments would be evaluated based on value, especially after the pandemic, there's gonna be fair amount of financial pressure to determine what is actually a good enough technique that would financially, would make sense for the healthcare centers. And I think the value based care it's gonna be a fair number. Other forces are gonna enter the realm of care and coordination of it. And I think that would make a much bigger role. The pandemic I think really accelerated the next generation of healthcare delivery because of the financial pressures that it created on the healthcare system during the time of the pandemic. In other words, post pandemic healthcare delivery is gonna be somewhat different. And it's gonna unfortunately take some decision making out of the hands of the surgeons and place it on the hands of the executives. Well, we sure hope that those executive will ask our input much more than they have now, till now. And I think it depends on the health care centers involved. So with that in mind, Sepi, I wanna say you as a country woman of mine, I'm so proud of you, just immense success. I mean, just tremendous surgeon in every respect, what you have done in your career. And it's truly, you've been a role model for many of us, including myself. So I wanna thank you again. Wish you all the best, really thank you for an incredible lecture, so beautifully organized, and we're gonna hunt you down again for giving us a lecture in the near future.

- Alright. Thank you so much Aaron. I Appreciate it.

- You're welcome. Thank you

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