Hello everyone, I'd like to welcome you to yet another episode of the Front Row series, the new series of the WNS, the new official educational website of the WNS. Again, this series features renowned experts from around the world with topics including skull base, cerebrovascular, tumor radiosurgery, and many more. And participants to this series have access to both live and archived events for CME, and for the first time participants have the opportunity to submit cases for expert discussion. Our experts today really need no introduction. We have Dr. Fadi Sharbel, Dr. Fadi Sharbel really has pioneered and spearheaded the entire field of flow measurements in bypass surgery, and he will be speaking about that today. Dr. Jacques Morkos, who is one of my mentors, will be speaking to us about math, physics, judgment, and skills, as well as innovation in cerebral bypass surgery. And last but not least, one of the known magicians of bypass surgery, Dr. Michael Lawton, will be speaking to us about the evolution of bypass surgery for the treatment of cerebral aneurysms. I'm George Zinonos, we'll start with our presentations with Dr. Sharbel. Please for any of the live participants, put your questions in the chat, and we'll get to them as soon as we're able. And as soon as we're done with the presentations, we'll go on with a case presentation at the end, and close with some Q&A. So thank you everyone again for sharing your wisdom for this wonderful event tonight. I'm sure both the live participants as well as everyone that's going to be accessing this presentations on the website will learn a great deal about this exciting topic. And without further ado, Dr. Sharbel, if you want to share your screen, and then we'll go on. Okay. Is it visible? Yes. It's perfect. Great. Well, first of all, thank you very much, Dr. Zinonos, for putting together this. Dr. Sharbel, I think somehow we see a, no, he's actually fine. I'm sorry. Are we good? Yes. That's perfect. Okay. So thanks again. Congratulations putting this together, George and Jacques, you've pioneered this. I mean, really the Miami series has been an outstanding success. You're continuing this in so many ways and you get the, you should get the, not only the applause, you do get the credit for having pioneered this in neurosurgery and the AANS benefits from that, I'm sure. So that's the topic, the role of flow measurements in bypass surgery for ischemic disease. And I will start with my disclosure related to the transonic ink flow meter that we use at surgery. The Vassal ink Nova system. I have no financial interest in that at the moment or for a long time. The objectives of this presentation are listed here. We'll go through them one by one in a narrative fashion, reflecting the evolution really of my thinking about this topic. But before starting, I'd like to acknowledge some key people. First of all, of course, our cerebrovascular faculty here at U of I in alphabetical order, they're all quite deserving and leaders in their own way. Ali Alaraj heads our CV endovascular section. You all know him very well. Of course, you know very well, Sepi, my outstanding colleague, Gursante Atwal, who's also a rising superstar in vascular neurosurgery, dual trained as well like Ali. Our fellows, I didn't mention all the fellows, I can't fit them, but the last three fellows really are more related to the cases shown in the slide. They help to care the patients, help with the surgery, perform many of these surgeries. They're each as outstanding or more outstanding as the other, and it's like your kids, you can't really have a preferred one, but truly phenomenal, each one of them. Thank you. Thank you to the residents as well. As one progresses in the training, we realize how important it is and how privileged we are to be part of training the future, and the residents each as bright, as engaging as the other, and we're truly delighted to be part of their life and their future. So to give you a quick up your shoe of where we are, that's the campus of UIC, it's a very large urban research university, which encompasses not only all the health sciences, but also the other sciences, liberal and engineering. So our institute is that arrow right there, it's the Neuropsychiatric Institute, which was completed in 1941, auspiciously, two days after Pearl Harbor, and was first founded by Eric Oldberg, who was the last resident of RV Cushing. So Oldberg comes to Chicago, founds the institute, first surgery is done two days after Pearl Harbor, so 12-9-41, that was a Tuesday, and interestingly, as a bit of trivia, the first surgery was by Oldberg assisted by Green, John Green, who went on to form the Vero. So if Mike Lawton is listening, he'll get a kick out of this. Oldberg was succeeded by Sugar, then Kroll, then my mentor, James Ausman, a giant of vascular neurosurgery, and then I succeeded him after his retirement. That's the campus today, nowadays, a lot of built up like you see everywhere else, but we're particularly thrilled about is what you see here. Just completed in September, this major project, which is the Surgical Innovation and Training Lab, which encompasses the entire footprint of the institute, truly a phenomenal place, where you wanted to bring together training and innovation in a beautifully pleasant environment, and we look forward to having you, Jacques, and George, and everyone else there, once what looks like travel is reopening right now. So it's the embodiment of the sciences coming together. We have, it's a concentric ring, in the middle are 24 stations for, say, microscopes or cadaver tables or angel suites, et cetera, and it's surrounded by two large operating rooms. The setting is aesthetically quite pleasing. You can see you can change the lighting. You have a living wall with natural plants. You can add a flick of a button, opacify the various partitions, so you can have privacy between one area and the other. Residents are truly enjoying this. They've been part in developing a curriculum with Gursante Atwal and Elie Alaraj, and every month we do one or two programmed progressive training sessions for the residents and other people. It's been a great success. Going back to my topic of flow measurements, how did I get started into this? When I was a resident, I was struck by the statement attributed to John Hunter. John Hunter was truly the epitome of the surgeon scientist. He really was very well known in his time for documenting everything he did, seeking answers. He was actually the mentor of the smallpox vaccination, so truly an amazing person. But he said, or it's attributed to him, that blood goes where it's needed. Is that true or not? It sounds true, and it's a very simple self-evident statement, but how come it doesn't happen all the time when we intervene on patients, especially with bypass surgery? That led me to the work that I did over the years. The environment was contusive because the university here has a wealth of engineering collaboration from which I benefited. This is where we developed some of those tools related to quantitative vessel flow measurements. The two tools that are available to us for quantitative vessel flow measurements, you're familiar with them, are the intraoperative ultrasonic flow meter, which measure flow, not velocity, and that's important. It's not a Doppler signal, it's a transit time ultrasound. It has all the qualities which you know, I know you use it. It's immediate, it's repeatable, and does not require contact with the vessel. It's proven itself quite useful in many settings. The other technology is the quantitative MRA. It chooses phase contrast MRI, which of course does not use contrast, and one can use it then in the perioperative period, although some centers have this on their MRI in the operating room. Extremely valuable over the years, and a lot of publications from many centers related to that. From these measurements over the years, we learned somehow to put together some sort of a reductionist view of why performing a surgery. Why is that surgery performed? In 2006, we coined those two terms, flow augmentation and flow replacement, which are really the two reasons one performs a surgery. One could add an intermediary third one, which would be a temporary bypass prophylactic, but it would really be in the context of flow replacement. Flow augmentation is in the context of ischemia. Flow replacement most commonly is for aneurysms, where the patient is at risk of flow compromise because of our intervention. A few words about how our protocol at UIC often were asked, how do we evaluate patients considered for flow augmentation, for ischemia in other words? It's MR-based. Of course, once we establish the flow compromise from conventional imaging, which is the angiogram and detailed angiogram, the three next tests we perform are one, quantitative MR in geography, where we measure the flow in the conducting vessels, all of them, which is very useful in large vessel occlusion. More so, it would be very useful because we measure the flow in the collaterals. The large collaterals, MCA, ACA, PCA, but also potential collaterals such as the middle meningeal or the STA, and that's very useful for EDAS, for example, or any other continuous longitudinal observation and quantification of flow progress over time. The two other methodologies are BOLD-based, so we do a global BOLD. This is another patient from the one I showed before, and this context is severe stenosis of the right ICA. You can see the CO2 challenge induces poor vascular reserve in the right MCA territory, as you see here in blue, and then we complement that. This is the same patient with the regional reserve, where it's a functional paradigm, which we use motor, memory, visual, et cetera. In this case, you can see that there is an absence of hemodynamic reserve in the primary motor area on the right side, and we do two tests consecutively to increase reliability. If all those three come together, we complement all this with cognitive testing on the patients discussed in conference, then we would consider those patients who are symptomatic, of course, for flow augmentation with an ECIC bypass. As we do this bypass, and as we do them repeatedly, the interesting question came up, what is driving the flow? What is the most important determinant of flow in vivo? And I put in vivo in italic, and initially, of course, we all go back to the thinking generated by the Poiseuille equation, the diameter of the conduit. While this is true and influential, certainly in the lab, but in reality, the clinical setting is not that important, and I'll show you examples of why. Really, what's important, what's driving the pressure in the context of what we do, is the pressure gradient, in other words, the demand. Another concept is the cut flow. Cut flow is simply in an in-situ vessel, such as an STA or occipital artery, is cutting that donor and seeing how much it can provide. This is a very, very important and useful benchmark, because it gives us an idea of the carrying capacity of that vessel. And this is where we have dispelled the notion that an STA is low flow and blah, blah, blah. This is, to paraphrase Jacques, nonsense. It's nonsense because it's what it is. The flow is what it is. Low flow, high flow are meaningless terms, really. An STA can provide a lot of flow, and it's important to measure it. Look at this, for example. This is someone who's getting a bypass for Moya-Moya, and you see the compromise here, which is pretty typical. And we're measuring the cut flow, and for this beautiful STA, the cut flow was only 9 to 11 cc. And it turns out, as you can see, that the reason it was so low, less than expected, was because there was a vein crossing this artery, which was coagulated but not cut, and it had caused a compromise of this artery. So you see the vein here, and by simply cutting this constriction, which overlaid the donor, the flow increased from 10, 11, to, here you see it, being measured 5 times, 5 folds. So two points here. One, had we not measured the flow, this vessel would probably have thrombosed, clotted behind the substruction by the time ready for the anastomosis, and the second one, one example of many I'll show you of why nothing changed here except the pressure gradient. There was a resistance, releasing the resistance increased the flow by 5 fold and not the diameter. The index then, the cut flow index, is simply dividing the bypass flow by the cut flow. And that leads to a lot of questions. The main one would be, if a bypass can give X, the donor can give X, and the bypass is only a fraction of XY, and what does that mean? And what we found is that the index was significantly higher in patent bypasses and lower in not patent bypasses, conversely, and was also associated with early versus late non-patency. And this was particularly true in flow augmentation bypass, as you see in the series that we published recently. So why do they fail, since they do fail, obviously? Well, we stratified this into poor indication, which would be type 1, meaning the patient doesn't need it, or technical problems, and I'll go through all of these. So what is type 1 failure? Type 1 failure is fairly common in a flow replacement bypass, because as you recall, the flow replacement bypass is a bypass that we perform to replace a deficit. So if the deficit is not there yet, the bypass is not needed, it's a type 1, and we don't have flow in the bypass. So here's an example where we are doing a large conduit bypass with a vein, 8 millimeter, I didn't say, mind you, I didn't say anything about flow, large conduit. Once this bypass is completed, the flow in it, however, is, and the clips removed proximally and distally, you see it's a huge bypass, 8 millimeter, it has only 24 cc's of flow, 24 cc's, and with every heartbeat, the flow is stopping, it's reaching zero, why? Because the carotid has not been occluded. So I narrowed the carotid, now it's more demand, and the flow increases to 54, it has doubled already, and when we narrow it even further, well, fully, by sacrificing the carotid, you see here it's fully sacrificed, so the flow goes from 24 to 54 to 83, it has now quadrupled, and by the time we're done, here's the anastomosis filling the whole hemisphere, and the flow now on the NOVA is 161 cc's, same vessel, same patient, all that changes the pressure gradient, so do not confuse conduit size with flow. So that's not common, though, in ischemia, it's not common. It used to be, when we did not have ways to detect flow deficit, this is an example of a patient that had a bypass to the posterior circulation, and acutely, there was a type one error, and you can see big PCOM. So this patient has an STA that's being connected to the SCA, the STA is red, the SCA is blue. You can see the STA flow goes from five in situ, 65 cut flow, to about seven after a bypass, so really a very poor index, and you can see the SCA flow before and after did not change. So there was no flow augmentation, no real use for this bypass. It's a type 1 problem because this patient did not need it. We hopefully don't see that anymore. We really don't see it because we select patients carefully. But we still see it over time. We see these bypasses fail over time in a more chronic fashion. We know that if we measure flow over time, and that's one of the values of sticking in one place, I've been in this place for 20 plus years now as an attending. So you can follow your patients over time. And some of them, you can see the flow, like in this one, who had a flow of 79, dropped to 37 because, and the bypass shrunk because of the reopening of the carotid. It was a dissection. So there's a reciprocal relationship between demand and supply. Now, the type 2 is the more common. And A is a problem with the donor. And there are real problems with donors that occur. They're mostly technical. For example, if there's a bleeding over the donor, I showed you that, and you coagulate it, you can hurt the donor. You can have problems with the donor if, say, for example, there is atherosclerosis. We're talking about ischemia. Be very, very careful with this double lumen thing. So what that means, you have to go to a fresher place. You've got to cut the vessel, get a clean spot. But thankfully, in this case, we had a nice bypass. But the double lumen is really very, very, very dangerous. That's a type 2A problem in ischemia. The anastomosis is obviously the most common. And the only solution for that is practice. And one has to do that. You don't need anything sophisticated. This is a very fine model that you can do on the leaf of a plant or a petal of a plant. But 2C is the most relevant. So 2C is a problem with the recipient. Yesterday, for example, I was doing a bypass when we had this problem. And atherosclerosis is common. So you can have a flap. And you've got to make sure you attack that flap. Otherwise, you have a false lumen. But it's common in flow augmentation, in particular, in Moya-Moya. So that's a great index on the left. This is a poor index on the right. Both bypasses are patent. The difference is in Moya-Moya, the territories do not communicate. So because they don't communicate, most people that advocate for direct revascularization recognize the need to bypass too many territories to avert this 2C problem. So that's known. And that's how we do it, of course. So here's a patient, poor flow in the left MCA. After Diamox steel, it gets even worse. So the cut flow of the trunk is 41. The first bypass gives you an index of half, 58%, because there's only 24 ccs in the first limb of the bypass. The double limb adds another 20, gives you an index of 1. So you're using all what this SDA can give you, trunk can give you, which seems to be good. Nothing wrong with that. And here's the flow. It increased over time, 95 in the trunk, and the two anastomosis. So that's good. Ischemic, same for hemorrhagic, same argument. Reverse the collaterals, et cetera, provide as much flow as possible. The so-called double barrel bypass, no doubt, provides luxurious flow. And on angiogram, and you can measure it, 74 mLs in one branch, 42 in the other. Same thing here, luxurious filling on the angiogram. So no doubt the double barrel bypass works and provides a lot of flow, like you can see here, a total of 153. Again, SDA can provide a lot of flow. So what's the problem? The problem is twofold. One, it's a progressive disease. We've known that from Suzuki's time. It changes overnight. It's dynamic. So what happens if you need another territory? And two, it does seem, if you look at the flow in these bypasses, you follow them over time. There's no doubt that the initial patency rate, which in our series was 96%, is not the same over time. So we started with 96% at day one. At one year, it's only 74%. There is a change, and we lose bypasses over time. And it makes it almost feel that we should not use all of our ammunition, so to speak, at once. So here's an example, Bad Moya. You can see the nice SDA. And I was planning to do a double, so-called double barrel bypass. But once I did the first bypass, which provided 70 cc's of flow, I reanalyzed the most, the distal one, the parietal one. Why? Because I said, don't waste it. Keep it as an EDAS, just in case. So it can work in case the frontal one involutes. And you can see the direct bypass is 122 cc's, and the EDAS is only 19, but at least it's an EDAS. So I didn't hook it. So that's progression over time. The next step was, okay, frontal one, direct bypass, end to side. Parietal one, side to side, but keep it in continuity also as an EDAS. Also good, not bad. And here's another one where I wanted to put a lot of flow, because this young diabetic lady had collateral through her ophthalmic, 90 cc's of flow going through it. So I wanted to use the anterior branch, but possibly use the posterior branch as well if needed. So what I did, I did two anastomosis with the anterior branch, a side to side and end to side double bypass, and preserved her middle meningeal. You see the double bypasses, 167 cc's of flow, a lot of flow, which involuted the ophthalmic flow. It's now 42 from nine. So that's quite good. And then the concept became, well, if I can do this, why don't I do it all the time? Meaning using as few vessels as possible. And this patient came along and had bilateral occlusion, beautiful anterior branch, not so good posterior branch, measured the cut flow, over 100 cc's. So I do a side to side, that's the recipient flow, which is very poor. I do a side to side first, 67, and I add an end to side, which is 40, and that gives us 110. So I'm using all the flow that this branch can give, and that worked out beautifully. So that became what we call a 1V2A, or single vessel double anastomosis, which would be the go-to vessel if possible. We can't do it all the time, but that's the preferred bypass. So that's kind of what it looks like. And preserving the middle meningeal, and then we presented that, we published that in Vascozzi's book, and then there's videos online that you can watch, and this is our more recent series in 19, looking at the small series. So what this can do is achieve all the goals. We vascularize as many territories, as few possible vessels, little trauma because at one vessel, and use, take advantage of all what the vessel can give. So in other words, an index of one. The slide variation on this, you can do something like this case here. You can do a side branch, you can check the cut flow. Here's the anastomosis being completed. What's interesting here is the ICG. So direct bypass and EDAS, you can see the rapid unidirectional flow in the anastomosis on the ICG, but in the distal ICA, it's bidirectional. So what's really interesting and telling is when you look at the flow in the MR, here's the trunk, it's unidirectional towards the brain. In the anastomosis, it's unidirectional towards the brain, and on the EDAS, which continues, is bidirectional. So the 1V2A, affectionately called minimax, addresses the issues that it's a progressive disease some of them do. Allows us to revascularize directly as many territories as needed. Allows us to use as much of what the vessel can give, strive for an index of one, and minimize the trauma. And the steps, of course, are here, smaller incision, one vessel, side to side. Preserve the natural collaterals of the middle meningeal. You see the anastomosis preserving the middle meningeal. Respect to the vein, you all know that. Retractor on the vein with a stitch. And we, therefore, continue. We persevere with the surgery, which is a beautiful surgery. It's almost something that we would have invented if somebody else, Yasser Gil, hadn't come up with it. But we enjoy doing it. But at the same time, we strive to see what we can continue to do better to understand this elusive problem. And it's thought-based, it's physiology-based, and it's a means to an end. So thank you, Jacques, Georges, everyone, and we look forward to the discussion. Jacques Charbel, every time I hear you speak about this, it's truly fascinating. I think you're on mute, Georges. Can you hear me now? Yeah. Yeah, I was saying that every time I hear you speak about this topic, it's truly fascinating. We will hold any questions for now, and go on to Dr. Morkos's presentation, which I believe is along the same lines, but casting a wider net. So Dr. Morkos, we're looking forward to your wisdom. Okay, my friend, you can hear me, correct? Yes, absolutely. Excellent. Well, always wonderful to be with my good friend of decades now, Fadi, and the journey continues, Fadi. Disclosures irrelevant to this talk. I'm gonna talk very briefly about a little bit continuation, of course, of what Fadi has talked about, the math, the physics, some computational flow dynamics of bypass, surgical principles and techniques, and some applications, very few examples of skull-based lesions, some unusual cases, and I guess what I call the 1D2R, what Fadi has called the 1V2A. Fadi was the first indeed to describe that variation, and I'd like to show you my series of 21 cases. Math and physics, what do we need to know to do bypass? Well, basic high school math and physics is all you need to understand at least the geometry, to remember that the Pythagorean theorem tells you that if you fish mouth the donor, you will increase the cross-sectional area by four times. You need to understand slightly, not in deep manner, the Bernoulli's equation to understand what happens to the energy of flow in a bypass, but you really do need to understand the equation that Fadi has talked about, the Hagen-Poiseuille law, because it's entirely equivalent to Ohm's law in electricity, and the equivalence is quite good, the delta P, the R4, the length that Fadi has just mentioned earlier. So you need some understanding of that. What is the relevance? The relevance is the geometry of how you build your bypass, your anastomosis. The donor to recipient diameter ratio is important. We cannot control the blood rheology. We certainly cannot control the morphology of the donor surface. As always in neurosurgery, cerebrovascular, we always seem to be following the research that goes on in the cardiac coronary surgery circles, and a lot of the basic bypass physiology, really, you can learn from reading the papers that are in the coronary literature. And there are many examples of failures. Fadi covered that very well. Just to remind folks that with too large of a donor, you will get low wall shear stress and intimal thickening. With too small of a donor, you will get high wall shear stress and endothelial injury. There is a sweet spot. Angle of forming the anastomosis, what should the ideal angle be? Many, and there's a huge literature on this, but maybe if I could distill some just basic practical points, the smaller the anastomosis angle will result in less turbulence, less stagnation, and more physiologic wall shear stress changes. It is fascinating to realize in animals, in humans, different species, that what the biology will, what rules the day is what rules the adaptive mechanism is the wall shear stress. It seems that vessels adapt to achieve a wall shear stress of 15 dyne per centimeter square. And that is seems to be the defining constant. So in this series, for example, the bypasses were done. You can see in one group, it was high and the wall shear stress was high. And over time, both series, both groups converged to what seems to be the constant that the vessel wants to achieve. And you can see the formula for the wall shear stress in the bottom right. The technical tips, make your donor as short as possible. Shoot for a donor to recipient ratio. Ideally, if you have the choice, 1.5 to two. Fish mouth the donor unless there is a large discrepancy. Try to achieve a low angle. Now, of course, you can't achieve a zero angle because anastomosis will be too long. So that is a sweet spot to compromise. Tend to put more sutures closer to the toe and the heel. And these are, again, some of the papers that will discuss many of those issues. Surgical principles and techniques is from an old chapter. Fish mouth will give you a cross-sectional area of four times more. In an end-to-end, it's nice to bevel. In a side-to-side, you need to know how to do a running suture at the back wall because there is no other way to suture these two vessels in a side-to-side. Placing the arteriotomy in a side-to-side, I like to do it in this compromised colored red position. Let's start with some unusual applications of bypass. If you don't have an STA, I'm sorry, in a posterior circulation ischemia. These are rare cases, but it's really an orphan disease. Remember that there is an occipital artery, topaica, and many other variants. I'll show you one quick example of that for a posterior circulation ischemia. You can barely see the vertebral basilar tree. This patient, you can see a stroke in the cerebellum, pre-op, and multiple posterior circulation, TIA. You have the occipital artery. You do a far lateral approach. You dissect the occipital artery. We're gonna skip through that. You open the dura. With respect to the recipient, it is nice to bring it as close to you as possible. Of course, be mindful of those big perforators that are in the tonsillomedullary segment. The closer it is to you, the easier it is. Bring it to you, and we're gonna do an end-to-side. You can see plenty of room. Sure, it's deeper than your STA, MCA, but plenty of room. It is certainly not particularly difficult. It is certainly much easier than a bypass to the SCA or the PCA. We're gonna do an end-to-side anastomosis. We've seen plenty of suturing already from Fadi, so we'll skip that. You construct your bypass. You do the flow measurements. And I do want to thank Fadi for truly pioneering the field of quantitative flow measurement. And I certainly do follow his school of thinking with regard to what to do with interoperative flow measurements. And that's the bypass completed. And there is a post-op angiogram showing a nice patent bypass. Bonnet bypasses, they're tedious, but they're very rare. I have done only two cases, putting a saphenous vein from one side to the other, from one STA to the other MCA, because there was no ipsilateral STA. This... Dr. Morkos, I think you accidentally muted yourself. Yeah. Okay. Can you hear me again? Yes. Unfortunately, you can hear me again. Yes, indeed. We can't see the slides now. No, now you will. Do you see it? Yeah. Okay. Back online. Bypass in skull base. Bypass in skull base. Bypass in skull base has become rarer and rarer for obvious reasons. Perhaps we've become more conservative. Perhaps... First of all, what does that look like? For example, because endovascular has, in flow replacement, has replaced a lot of what was done in the past, because aggressive tumors or infections, you could use it still, but if it engulfed the ICA or the vertebral artery and they need to have failed the BTO. So that pi has shrunk significantly, but there are still cases of skull base lesions. Now, this is not skull-based lesion, but this is an HIV-related vasculopathy leading to this aneurysm and with a preaneurysmal stenosis not appropriate for flow diverter. So I did a saphenous vein bypass. You can see the sequence of pictures from the cervical to the M2 and then trapping of the aneurysm. Or this basilar dolicoictatic thrombosed aneurysm causing mass effect on the midbrain and pons. And you need to know how to do a radial artery graph to the PCA. And you can see it here at the end of the bottom right. Or examples of tumors. This is a very nasty glomus jugularis tumor. And you can, by looking at these pictures in order from A to H, you can see the story of this patient. I removed the glomus. You can see the surgical result initially. Left a tiny piece on the petrosal, petrous carotid. Radiosurgery failed, regrew. I operated again, sacrificed the carotid, did the saphenous vein bypass to the M2. And now, 11 years later, has grown again. She is actually in the hospital as we speak. And we are in the process of embolizing her. Five different sessions. Look how nasty it is and has parasitized from the cerebellum. And I'm operating next week. It's not going to be pleasant. But of course, the bypass is preauricular. And therefore, it's not in my way of free operating. And very rarely, of course, but sometimes you need to do it. A bypass for pituitary adenoma, multiple surgeries, multiple radiosurgery and fractionated radiation. It kept growing, invaded the right cavernous sinus. So that's when you do a cavernous sinus exenteration. And we sacked the carotid. She did not tolerate the BTO. We did an M2. I did an M2 bypass. And you can see examples of cavernous sinus exenteration and a complete resection of the bottom right. Now I'd like to discuss my series again as quickly as I can. This is in manuscript submitted and the sub-series of it is already in press. The 21 cases of 1D2R that I'll share with you. So this is ischemia and Moyamoya disease. I looked at 21 years of practice. I've been in practice 26 years, but I looked at my last 21 years. I divided them into Moyamoya disease, Moyamoya syndrome, and steno-occlusive disease. We'll skip the usual demographics. But here is, let's first look at surgical morbidity of direct bypass. 30-day morbidity in my hands in this series was 10%. What does this 10% include? Ischemic stroke post-op, 0.6%. ICH post-op, 3.1%. Then some other stuff, subdural hematoma, wound complications, respiratory failure, and MI. You bunch everything together, you get 10%. If there was incomplete collateralization pre-op on an angiogram, remember, in spite of symptomatic presentation and a poor vasomotor reactivity, if there was complete collateralization, 36% of the cases of the direct bypass will occlude long-term. If there was no incomplete, I'm sorry, if there was incomplete collateral formation pre-op, the patency rate stayed very high long-term, 96%. Huge difference, statistically significant. You can see it here in graphic format. Now, that does not mean we should conclude that the patients who had on angiogram complete collateralization should not have been bypassed because they were still symptomatic and an angiograph is not a quantitative measure. It's a visual depiction. It certainly means that those patients, for whatever reason, had higher propensity to develop the indirect collateralization post-op spurred by the craniotomy and the direct bypass. In my series of 162, the MRS improved significantly, modified rank and score over time, and when I looked at the three different techniques of what I'm calling 1D1R, 1D2R, and 2D2R, there was no statistical difference, but you can clearly see a trend in higher CFI, as that Fadi talked about, as certainly makes perfect sense, and long-term patency. So now, since I knew, of course, Fadi is here on the talk, so I thought I would compare and contrast, because this is very teaching, the UIC series of 2019 with the current series of mine. I am sure there isn't much difference in technique. I don't think so. So what does my series, how does my series differ? I have a higher percentage of using 1D2R and 2D2R. It's about 29 percent in Fadi and Seppi series of 2019 is 17 percent, but very importantly, it seems, and Fadi can reconfirm, that the UIC series has, they use concomitant EDAS in 35 percent of their direct bypasses. I've used none in mine. The follow-up is slightly longer in the UIC series, 2.1 years versus 1.75 years for mine, which results in, in my series, a 91 percent long-term patency versus a 76 percent, and I think it's, and I may be wrong, but I think it's a concomitant use of EDAS in the UIC series. I don't think there are other plausible explanations, which perhaps also explain the other discrepancy between the Miami series and UIC, is that in my series, as hard as I looked in the 162 cases, I cannot find correlates between CFI and long-term patency. My long-term occlusion rate is about 10 to 11 percent, regardless of what the CFI is, while Fadi has shown you very nicely in his series, in their series, 54 percent specific occlusion rate if their CFI was less than 0.5. I could not, I cannot replicate that in my series, and we can certainly, you know, speculate why that is, and I mentioned the various causes. It's important to note, then, in experienced hands, the stroke and ICH complications of direct bypass is low, if you choose your patients appropriately. In my series, it's 3.7 percent, and when you follow patients over time, a total of 6.2 percent, which include those 3.7 percent, will have strokes or ICH on long-term, when I say long-term, it's about two years, no, I'm sorry, it's about almost three years, two years and 11 months follow-up, one death in the series, as I mentioned, and the long-term patency of about 90 percent. So that's, that's really, those are the discussion points that we could talk about, perhaps, and very briefly, the 1D2R series of 21 cases that is in press, and I thank Nick Kahn, my wonderful fellow, and several of our residents who looked at the data. I think I can, well, I can skip the video. Fadi has shown, has shown you a nice 1D, well, he calls 1V2A bypass. It's, it's really same thing, reminding you of the math and physics involved in it. This is, this is what I mean by incomplete collateralization. You overlap the angiographic shots, and you try to see, do you end up with a bare area? Yes, in this case, this is a bare area that is uncompensated, and this patient will have a 96 percent long-term patency of their bypass, versus the ones that have incomplete. So in this 1D2R series, these are the steps, indeed, one, two, and three. You line up the two recipients. You generally want to do the side-to-side bypass first, and then the end-to-side, for obvious reasons. You calculate interim flow, as Fadi has alluded to, then you calculate final flow, and here are the results. I'll skip the demographics. The results are excellent, 100 percent immediate bypass patency, long-term patency 90 percent. The cut flow index, indeed, did grow from 0.64 to the, from the, after the first anastomosis, 0.94 after both anastomoses are done. The overall donor-to-recipient flow increased, on average, by 50 percent by adding that second anastomosis. There was, I managed, I did some cases end-to-side first, some other, and most of the other cases side-to-side first, so I had the opportunity to see if it made a difference, and it didn't. You end up with the same final flow in general, but this is what happens. You have a cut flow of 57, an intermediate flow of 36, and a final flow of 52 after the second anastomosis. It doesn't matter in what order you do it, side-to-side or end-to-side first. This graph analyzes that and shows that there is no difference. Clinical outcomes patients are getting better, at least based by MRS. I know you're, it's too late in the evening to explain the calculation of the resistances in the circuit, but when the paper comes up, you can certainly look at the supplementary material to explain the equivalence with an electric circuit for each component in the double, in this double bypass. So there is certainly a benefit for second anastomosis, and this gave me the opportunity to build up on what Fadi has pioneered with the CFI. This is a perfect opportunity to use both CFIs, so by dividing CFI final by CFI intermediate, I'm calling it SERA, second anastomosis relative augmentation. That will tell you how much relative augmentation you've done with the second anastomosis, and by another related concept I'm calling SASE, that second anastomosis sink index, this final flow of the second anastomosis divided by final total flow, that will tell you how much the second anastomosis has created a sink from the first one, and that's what it looks like. This is your typical case with a mature bypass. This is the only patient in the series that has occluded bilaterally in a delayed manner with vigorous indirect flow. You can see his right at the top and the left at the bottom surgeries, both occluded. This is a summary of the benefits of 1D2R. I, too, like Fadi, do like it when indicated. It is obviously not suitable if the STA is really tiny. It might not be appropriate for inexperienced surgeons. You don't want to screw up two anastomosis by screwing up one vessel, but it certainly cuts the operative time significantly by not having to go look for a second branch, and particularly with the wound problems that you can have. I will conclude by reminding you of these important flow dynamic factors, perhaps the concepts of SERA and SASE, perhaps other surgeons will find useful in their double anastomosis series. I will stop sharing, and thank you very much. Dr. Morkos, thank you for a spectacular presentation. I'm going to toot the forest of both the science as well as technical pearls with bypass surgery. Again, for the audience, please put your questions in the chat for the live participants. Dr. Lawden, thank you very much for joining us. We look forward to your presentation on the evolution of bypass surgery for cerebral aneurysms. Okay, thank you. Let me just get this going. Let me know that you can see my title slide. Can you see the title slide there? Yes, it looks perfect. Okay, great. Thank you. All right. Well, I'll make this brief. I just wanted to finish on a note of innovation and evolution because I think this is one of those procedures that we do that allows us to be creative and allows us to innovate. I just wanted to share with you what I call three cases of innovation. The first is intracranial to intracranial bypass, and I'll share with you this combination bypass. Second one will be fourth-generation bypass because I think conceptually, if we want to advance things, this fourth-generation concept is a new way of thinking about bypass and expands our framework. Finally, novel applications. I'll talk about the binderine bypass for macrovascular compression syndromes. This is a chart that just summarizes the various categories of bypass, the seven different bypasses. You can see that at the top of the list are the ECICs and second, the ECIC with the graphs. This next cluster of four are really what I would call the ICIC bypasses. That's, I think, where the field has moved to these more self-contained reconstructive-type bypasses. Finally, the combination bypass is the seventh. What that does is it just brings together any of these others for a multiple bypass like what Jacques was just showing. Here's an example, giant ACOM aneurysm. You can see it here on the axial and sagittal imaging. Most of this aneurysm is thrombotic. When you look at the actual DSA, the filling component is quite small. But for what we need to do here, we need to basically rebuild the anterior circulation in the ACA territory. We're going to use the M2 as a donor. We're going to connect that to the A3, distal to the aneurysm. Then we have to recreate an ACOM with this A3 to A3 bypass. What you're seeing up at the top is code. If you were a computer scientist and you wanted to summarize this concept and this kind of operative instruction, you could do it without saying a word with just this code. I'll talk more about that in a minute. Anyway, to break down those steps, we've got inflow naturally from the A1, we've got communication naturally from the ACOM, and we've got outflow naturally from both of the A2s. If we're going to rebuild all of that, we need an inflow that's new, and that's the M2 radial artery graft A2 bypass. We need a communication, which will be our A3, A3 in situ. Then finally, the outflow, we're going to use the natural pathway here. We're just going to do a distal occlusion instead. How does that look? Well, here's the view. This is our trans-sylvian view. In order to do this, obviously, we need access both to the inner hemispheric fissure in the midline, which you're seeing here as the flap gets elevated against the sagittal sinus. We also need the trans-sylvian corridor. Here is the pericolossal view right down the inner hemispheric fissure. You can see the A3s. What's so nice about intracranial to intracranial reconstruction is that there are many places, four key ones really, where these brother and sister arteries come together in parallel. They're naturally built for us to use our bypass techniques. There's that interluminal suture technique that you need if you're doing a 1D, 2R, or if you're doing this A3 to A3. This is really step one, just rebuilding the ACOM. Clips come off. You can see nice flow here. Now, we turn our attention down to our second corridor. This is now a view of the ACOM at its base. The A1 is here. The A2 coming out of the aneurysm is here. This aneurysm just keeps going and going. What we're going to do here is we're going to plug into the A2. Here's our arterionomy, a very large muscular recipient here. Very favorable for bypass. You can see the short segment radial artery graft coming in. This was just an end-to-side anastomosis. We've seen a lot of suture techniques, so I'll zip through this. We get that in place, we close the graft so that we don't have stagnant blood within it, and now we run up to the sylvian fissure, and this is one of our N2 arteries here that will serve as our donor. And so we'll finish off this connection here. Notice how I'm sewing interluminally. This is exactly like what you just saw with the A3-A3 in situ. This is an interluminal suture line. This is going to be relevant when we talk about fourth generation bypass, because this is not the usual way that most bypass surgeons sew this. But you can see we've taken care of that interluminal suture line. We now come out with our exit stitch, and we can do the second line. And the advantage of this fourth generation construct is that you don't need to move the artery at all. There's no movement of the graft as we normally would with the flopping of the graft from side to side, which means we can shorten it, we can facilitate the suturing, and it's just a nice expeditious way to do that. So now we've got our N2-A2 bypass, we've got our A3-A3 bypass, and now what we do is we simply trap our giant aneurysm. And what this does is it totally changes the flow dynamic. Instead of going from A1 through the aneurysm, we're now closing off the A1 here with this distal clip. We don't want our bypass to fill the aneurysm across the acom, so we also have to close the origin of the A2 on the ipsilateral side, which is what this clip is doing. And now what has to happen is that blood needs to go through the bypass, needs to go up the ipsilateral A3, A2-A3, go across the A3-A3 bypass, and down and around to the contralateral A2. And what you're going to see on this icy green is filling of the recurrent artery of puber. We look right in this little space here, you'll see this little artery here, that's the pulsating recurrent artery, which tells us there's no other way for that artery to get flow other than to have it zip around the whole circuit that we've created from the bottom around to the top. And so we've closed things down, and if we look at our post-op, you can see here's our combination bypass with the jump graft here in purple, with our acom reconstruction here with the A3-A3 side to side, and you can see how now this flow comes down and around and fills retrograde down to that recurrent artery of puber at the base. So it's just one example of how I think giant aneurysms are a different entity. They, in my view, are better treated with the bypass strategy rather than trying to attack these directly. And you can see the numbers here. Of all the 200-plus giant aneurysms I've done, about half have been with the bypass strategy. So I think it's a good way to go for these extreme complex aneurysms. Now, more on the fourth generation bypass concept, there are two variations. The first is if you're going to do a conventional construct but with an unconventional technique, and that's what I just showed you in that bypass. This is an example of an end-to-side anastomosis but sewn intraluminal. This is not the normal way that we sew our bypass for an end-to-side, but by doing it with the in situ technique, it allows us to shorten our graft. It allows us not to have to mobilize vessels, and we achieve the same result. Now, the 4B bypass is when you use an unconventional construct using whatever technique is necessary, and we'll show you those as well. But if you get the fourth generation concept, then you can take our seven bypasses here and take this table and essentially expand it and have multiple options for doing re-implantation, for example, multiple options for doing re-anastomosis, and multiple options for doing intracranial-intracranial bypasses. Here are some examples. This is an example of re-implantation. You can do it as a type three, which means cut it off one side, swing it over to the other, and sew it with a conventional structure. You could do it with a type 4A, which means do the same thing, but sew intraluminally if you don't have enough length to move things around. Or you could do it with a type 4B, which means instead of an end-to-side, you can do it with a side-to-side as shown here, or with an end-to-end as shown here. So I'm going to show you some MCOMs. The middle communicating arteries are for these really complicated aneurysms, dysmorphic ones that have, like this one, multiple arteries coming from the sidewalls. And in this case, we'll do a double barrel STAMCA bypass or what Jacques would call a 2D2R and get that into place. But then once that's in, we're going to bring these ends of the outflow arteries together with an end-to-end reimplantation, which you're seeing right there. And that creates your communicating artery, which allows the flow and the bypass to then redistribute. Then you allow nature to make the decision about how the flow needs to go. And I think nature is always smarter than we are when it comes to redistribution of flow. So I'll skip this. This is just the STAMCA bypasses going in. There's nothing new or fancy. But here, once those are in place, we can then shut down this aneurysm. It can completely collapse and trap. And now we can take these trunks that come off of the aneurysm off. We can do an end-to-end reimplantation. And you'll notice how these recipients are huge. The STAs are small, probably less than half the diameter. So this communication allows flow to decide for itself how it's going to redistribute. And I don't know if you caught this, but that was also a type IVa as well as a type IVb because we did an intraluminal suture line on the deep side. So there's our finished end-to-end reimplantation. We've got our communicating vessel here. We've got the two STAs plugged into each side of the communication. And now you can see with the STA there that the redistribution of flow takes care of itself. We can do an interpositional equivalent of the MCOM. And I'll show you what that looks like. This is an aneurysm that I clipped in San Francisco years ago. You can see a picket fence here that nicely, what I thought, reconstructed that. But on five-year follow-up, you can see here aneurysm has come back. It's because there's dysmorphic pathologic tissues here that were incorporated into the reconstruction. But what we're going to do, we're going to first do a high flow bypass. We're then going to create an MCOM here by connecting the two M2 trunks. And then we're going to trap distal wave. So that allows us to then create this communication segment, allows flow to redistribute. And it's really just one input artery rather than multiple. So I'm taking you now to the operating view. This is the aneurysm. This now is the proximal implantation of the graft at the external carotid. You can see the nice aortic punch technique. You can see the anastomosis. Now we're tunneled up and we're doing now the distal implantation here on the temporal division. And you can see standard technique, just getting that distal anastomosis taken care of. Normally, this stump here that we're sewing into is a dead end. And if we just were to occlude the aneurysm there, you wouldn't really use that. However, if we repurpose that as a new donor, you can see how we free it from the aneurysm. We can swing it over now to the other side of the bifurcation. And we can re-implant it now as a donor. And so we're creating our MCOM here. This is the interluminal suture line. Here's the extraluminal suture line. So here are the two anastomosis here and here. This is our communication. And now we can trap the aneurysm. This is just showing how there's some lenticular strides that come from the base that keeps us from a complete trap. We're just doing a distal occlusion. And here now with icy green, you can see our MCOM in all of its glory and here postoperatively doing the job. So the third and final point is novel bypass applications. One thing that I see not infrequently are these patients that come with the other kind of arterial degeneration, the elongation type. And when arteries elongate and run out of room to live, they buckle and they compress nerves or brainstem or other things in their wake. And so what I've learned over the years is that it's easy to come on these arteries and pull them laterally towards you through a standard lateral skull base exposure, but that's not the way the artery needs to be repositioned or transposed. It needs to go forward and medial rather than lateral and posterior. And so I think for many people trying to solve this problem, they've been doing it wrong. This is an example of that kind of buckling of the brainstem that that tortuosity causes. And if you fashion a sling and bring it to the clival dura as shown here with this aneurysm clip technique, you make a sling that lassoes the artery. You've punctured the clival dura here. You create a little dural sleeve that a clip blade can slide into. You feed the tail of the lasso through that and you anchor it right here to the clival dura. And that moves the artery in a way that's anterior and medial rather than further in the direction of pathology. So that is the answer. And I'm going to skip these videos and take you to this, which is the bypass solution. So this is a similar case. You can see elongation, buckling of the artery and compression of the seventh and eighth nerve complex. And this is what it looks like interoperatively. The problem with our sling technique for something like this is you just simply have too much artery. And so what we do in this case is what we call the binder ring bypass, which means rather than sling the artery forward and medial, what we're going to do is we're going to transect the artery. We're going to reroute it around the nerves and we're going to bring them back together in the form of an end to end reanastomosis. So if you think of the binder ring in your notebook, you unbuckle it, you reroute it around the nerves and snap it back together on the other side. And what that does is it positions the pathology now on the outside of the nerves. You don't have to worry about decompression because the artery can continue to grow over time. It can continue to elongate as much as it wants. The artery is now repositioned on the inside. Here's a little graphic just showing this, how you undo the binder and you sew it back together and then you solve your problem. So here's what this case looks like. Here's the pathology. You can see the compression here on the nerves. And by just pulling this forward, there's just too much artery for an effective sling technique. And so what we're going to do is we're going to trap this. This is all the B4 segment. This was proximal to the BBJ. So there is no ischemia time. We can simply transect this artery. I'm going to try here and advance this for you. There the artery is transected. We reroute it over the nerves, lateral to the nerves rather than under the nerves, and we sew them back together. So this is a type 4a because we're doing this intraluminally as you see here. And here is the stitch work. I'll just take you to the end. And now at the end of the day, you see that the nerves are medial to the vascular pathology. It doesn't matter how tortuous or how large those get. And this has proven to be a very useful technique as a last resort for these unusual cases. So I'm going to wrap this up with this idea. Bypass surgery is meant to be creative. It's meant to be innovative. I was really keen on giving other surgeons tools to be inventive. And so we came up with a language of these bypass symbols. We have firing diagrams over here for the circulations. We have symbols worked out for the different anastomoses. And what's nice is you can actually draw schematics. This is what we call our baro bypass coder. It's on our website. If you have a crazy idea and you want to build a new bypass, you can go in and you can add your little elements here. You can build a bypass and this coder will produce a little schematic that you can then print and put in your slide presentation or bring to the operating room or show your residents or whatever it is. And it's a way to communicate. This is about not only capturing ideas that come to you in the middle of the night, but also communicating them to your team. So that's the bypass coder. The idea of nomenclature comes from this paper with Al Roten. We wanted to create alphanumerics for the entire circulation, which were not completed at the end of his career. So we did this together. And the goal was to create a bypass code, which you can see here. These are the various elements. They bring together the side, the segments, the donors, the recipients, the technique. So in one string of alphanumerics, you can have the entire recipe for creating the bypass. Here's an example how for this particular double re-implantation technique, you can communicate the entire structure down to the type of anastomosis, the technique you're using, and all of the different components with this bypass code. You can also do it with schematics. But this, I think, is even more elegant once we embrace the language here. And this is a paper in press. Just looked at Galley's shortly ago. So it should be out real soon. So you can see if you like this and give it a shot. These are some of the MCONs, just to show you how even some of these very complicated bypasses that I've been showing you can be reduced to this code so that there really is no confusion whatsoever about the donors, recipients, the sign, type of anastomosis, which is within this parenthesis. And you have everything that you need there. So I'll finish with this slide. I think mastering aneurysm surgery is about many of these steps. But bypass surgery is a big part of it. And I really think that it's one of those rare opportunities that we have to be creative, to be innovative. And I certainly have enjoyed sharing that topic with these innovators in Fatih and John. Thank you. Thank you so much, Dr. Lord. And certainly stunning cases that perfectly illustrate how when you have the tools, you can, again, be creative and innovate and really push the boundaries of what's possible. I want to be respectful of everyone's time. We'll show just a quick case and proceed to a couple of questions, Q&A. Can you see my screen OK? Yes. Everything OK? Yes. All right. So this is a case that I just treated recently. It's a 63-year-old woman that presented really with just a headache. She was trying some aspirin and Tylenol, no relief. And when she came, she was neurologically intact, including her visual fields and proprioception. This was her CT scan. So you see an intraparenchymal hematoma, somehow surprisingly sparing her visual fibers and also the connections with the primary somatosensory cortex. She got a CTA. And other than that sort of glanced through quickly there, but there was questionably a small abnormality there, but nothing that really actually the radiologist didn't even call that. She also got an MRI immediately after. This is a T2. As you can see, there may be a round structure there within the clot, but again, very questionable. And the contrasted images, all this, almost like this roundish structure in the distal fissure. And please have me stop and go back if you would like me to look at this again. Of course, she went on to have an angiogram, again, showing this abnormality sort of in the distal fissure. so like a zoomed up view and also like the 3d recon that she was moving a little bit so it wasn't very informative George many so I'm sorry interrupt you we can't quite see is it one vessel or two vessels coming out of this abnormality great question it is or it was difficult to say it was difficult to say even I know you don't have the benefit of seeing sitting down and and looking at and the angiogram in detail but it wasn't it wasn't quite clear we had we asked her again she had no evidence of any section or she wasn't an IV drug user she wasn't anything like that so again I'll be happy to go back and you know go through some of the imaging but I like to hear what what are your thoughts right now I guess we'll start with dr. Marcos well I mean you know it's a distal MCA distal fissure aneurysm you need to go in and operate on it and you've already mentioned the things that young trainees should think about mycotic aneurysms and cardiac echo and valvular disease and so forth there was a strange case of an atrial myxoma and that embolized and caused an aneurysm distally in the location similar to this so you need to rule this stuff out but but you need to operate on her because whether it's a distal dissection or or an unusual aneurysm that ruptured and I can't quite figure out what bypass construct you need but clearly you need the simple you always want to try to do the simplest you get your STA dissected on the way in and you preserve it and whether you end up doing an end-to-end anastomosis without using the STA or using the STA it's a judgment call interop but do you think this is potentially dissecting a dissection I think so right yes actually about yeah I agree with Jacques I think that's the presumed diagnosis is either an infectious etiology for this or a trauma it's always possible or some spontaneous but it's clearly if use a former certainly irregular like aneurysm distally primary reconstruction is probably not going to be possible even if it comes from one vessel as a sidewall that means the disease is gone but really the question come becomes here is what do you really really need to do a lot of things you can do I will tell you that one neat trick that I learned from Bart Bundesbahn was a few tricks is to check the collateral by by cutting once you cut it and you're about to either read anastomosis or connect it together or do a bypass or whatever it is is to see the backflow if the integrate flow and once you cut it backflow is the same that means you have plenty of collaterals you can still try and do it an asthmosis but if it's not feasible maybe you have too long of a gap or you have to end up doing a much larger surgery than you expected then you can just take that vessel and you're done with it so just another element to consider in your armamentary. Dr. Long? I agree with everything that's been said I think now this is a classic distal MC aneurysm that's perfect for what I call the flash fluorescence technique so rather than worrying about a complicated bypass deep in the insular spaces you can simply use that hematoma get down to the proximal artery put a little clip on the inflow do an icy green see where your field is dark that'll tell you on the cortical surface where your recipient needs to be and you plug in a simple STM say bypass and and call it a day I think it's a really elegant simplification of what would otherwise be a tough bypass down right very words of wisdom that's exactly what what I did nothing too complicated is the STA run sorry showed you earlier showing the the robust at least parietal branch and the aneurysm was somewhere here so nicely opposed I know we've seen many nice videos today nothing too spectacular but harvested the STA on the on the way in I didn't harvest the I again I didn't know if there were two branches coming over based on the on the angiogram or just one so I left the frontal branch in continuity at least in the beginning to see what what we would need and then went to that turning the incision backwards where the dot is is where the aneurysm was a with image guidance I think it's important to use image guidance in this case at least when you're at my level with not that much experience and initially I just wanted to sort of lay the land so we I wanted to get it you know somewhat of a proximal control or at least find get a glimpse of some of the m2s there so found the m2s but it was it was pretty it was pretty tight so I opened up just to get a little of the clot without completely evacuating the claw to unroof the aneurysm and that gave a little bit of slack and then I started a little bit more distal in the fissure to go from distal proximal and dissected down to the aneurysm here is that actually that the aneurysm where there's two vessels were coming so close together was also in almost impossible to see it was a sizable aneurysm completely flattening the sidewall so now we did exactly what Dr. Long said so I put a clip on the proximal end of the aneurysm and then did an ICG and then quickly removed it and indeed it was just one branch that was fed distally I don't know if you can see my cursor but this this angular branch there so afterwards as again it was said earlier it was fairly a fairly easy thing to do if I had used flow measurements as Dr. Charbel said potentially you could have just sacrificed it but we chose just to do the anastomosis I just because it was just one branch I sacrificed the frontal branch prepared the vessel and then did the distal anastomosis and you saw multiple anastomosis today so we're gonna spend too much time here but very straightforward very straightforward bypass superficial nothing too complicated I still didn't want to go and do anything else in here because I it looked like actually a regular aneurysm no dissection so it was completely encircling that the periphery of the of that M2 So then trapped the aneurysm you know approximately this way there it's good flow even retrograde going in the fissure so there were there's still some perforators there that were fed even going up to the aneurysm. I'm not going to belabor this but this is very chronic appearing heavy thrombosis aneurysm so I chose not to do anything with it just evacuated the clot as better as I could there in the cold day. So I could have done a little bit better job evacuating some of the clot but I didn't want to chase it too far because he's going under the primary motor cortex and sensory cortex. She woke up fine we did a an angio on the third day for my angiogram and it was nicely trapped in that area was nicely vascularized by the graft and she ended up being well actually because she didn't have much subarachnoid blood she ended up leaving early. So just a couple of questions and I know it's been a long day I know Dr. Morkos had to leave but there's a couple of questions for our experts. Dr. Chabelle what do you think the most important application of flow measurements has been in bypass surgery in which specific application you would say if you had to choose one? I think really it has it had to do it would be the case where which allows you to do the most minimal possible flow the replacement bypass in the ECIC form. In other words it prevents you it obviates the need for more trauma by electing to use a larger conduit so it spares the patient the trauma. It confirms that the cut flow is sufficient to replace the deficit that you have and therefore allows for the most the least traumatic and invasive and intervention. I think that that that kind of distills it to its essence and of course there's all the other things that we learned from. Dr. Lon from from all the magic bypasses that you ever performed which one has been your favorite? That's a tough one. I get bored easily so what I like about bypasses the variety. I would say that you know some of these combination bypasses these milcoms those are exciting because they're they're fancy they're elaborate but you know I the reason I like this it's not because I have one that I keep doing because it's my favorite it's because you know we're not cardiac surgeons doing the same thing over and over again. We're neurovascular bypass surgeons and we mix it up constantly and so that's what's fun about it. Well I I know it's been a long day for everyone and I know that's at the end of a long day. I want to deeply thank you on behalf of the AANS and everyone here for all your wisdom really spectacular cases and and pearls of wisdom. I know I I certainly learn every time I hear you speak and as me I know many other young neurosurgeons that consider you mentors from afar with your teachings. This again will be recorded and on the AANS website for everyone to access and to reinforce the knowledge and look at your leisure. Thank you again and we look forward to seeing you for another episode of the Front Row soon.

Dr. Jacques Morkos

math

physics

surgical principles

bypass surgery

Hagen-Poiseuille law

blood flow

fish-mouthing

anastomosis angle

skull base lesions

posterior circulation ischemia

1D2R technique