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Grand Rounds-Advances in Vascular Microsurgery: Application of Fluorescence Video Angiography

Aaron Cohen-Gadol

July 11, 2011

Transcript

- Hello ladies and gentlemen, my name is Aaron Cohen from Goodman Campbell Brain and Spine in Indiana University Department of Neurosurgery. I would like to welcome all of you guys this evening for joining us for this presentation, which will be a discussion regarding advances in vascular microsurgery with some emphasis on description of application of fluorescent based intra-operative video angiography, I'm gonna go ahead and call this fluorescent-spaced angiography also known as ICG, and that stands for indocyanine green dye. So what is this technology of ICG? It really technically is a method by injecting a dye into the vessels and being able to evaluate by lighting up the vessels through the microscope. In other words the microscope will only see the dye and will be able to tell us how the vessels look and how if the aneurysm or AVM still there. We'll start with a description of the disclosure. None of which really interferes with the presentation this evening. So what is the basic mechanism of ICG is we inject the dye into the vessel and at the anesthesiologist usually does that, and that binds to some of the proteins in the vessel. And eventually as the blood reaches in the brain or the area of the surgery, the light from the microscope causes a special camera to only see the vessels. And that's really an intra-operative angiogram through the microscope, only lighting up the vessels and nothing else. So what are the applications? Well treatment of the vascular disease of the brain spinal cord, we need to see the vessels very well, such as annual aneurysms, AVMs and revascularization surgery. So what about aneurysms? Well, if the aneurysm is clip, we wanna make sure the aneurysm is obliterated. So there is no dye that goes into it. So that's one mechanism for aneurysms. The other one is we wanna make sure the clip doesn't cause any parent vessel compromise. So by doing the intra-operative angiography, you can assure that the vessel or the parent vessel is patent and we'll kind of go through some of the additional applications of ICG. And that includes assurance of the retrograde collaterals. If you're doing trapping of the segment of the vessel that is involved with the aneurysm, and also you can push the limits of ICG and assess the degree of flow, as you will see in some of the videos momentarily. So how about the AVMs? It's very simple. If you inject a dye and you don't see the dye around the resection cavity AVM is gone, and that's a good application for ICG in terms of AVMs. How about bypass? If you see good dye going through around through the vessels and the bypass graph, that means your graph is patent and it's immediate it can give you really immediate feedback without waiting for the intra-operative angiography. So what are the advantages. Again there is no interruption of surgical workflow because you using your own microscope to assess the vessels into an angiogram. And there is an immediate correction of suboptimal clip results, because you can see right away if the clip is compromising the parent vessel and potentially that could decrease the risk of post operative ischemia. And it has a high temporal spatial resolution because it's very immediate and you can see the flow as it starts from the vessels. And so they're easy to use and potentially decrease the need for postoperative and geography. What are the disadvantages of ICG? The structure has to be visible in order for us to assess it patency or it's compromised through the intra-operative ICG angiogram, and sometimes not all the aneurysm are visible through the microscope and that can compromise the degree of assessment through the ICG. And more importantly, calcifications were thrown by may not allow the camera to see through the vessels and see the dye. And therefore that can be a problem and can mistakenly lead the surgeon to believe that the flow is compromised. So let's talk about ICG and again the Zeiss microscopes that I use are very well-equipped to this device and I have found it personally very useful. Let's go ahead very quickly and go through some case presentations. Let's talk about first, some aneurysms and see how ICG can help. Let's start with a case of a 43 year old male with an incidental one centimeter left MCA aneurysm. I believe we all agreed this should be treated. I think surgical treatment is most indicated as you can see the aneurysm has a relatively broad base and it's on the left side. Let's go ahead and start our surgical video here. This is a left frontal temporal craniotomy. As you can see the Sylvian fissure and the brain, and this is the left frontal low and left temporal low. We start by opening the fissure using microsurgical techniques. As you guys are very familiar with. I have Victor Chan one of my colleagues who can communicate with me through my ear. So if you guys have any questions, please feel free to use the chat function below the screen. And he will let me know through my ear. And I'll be happy to answer those questions for you. Do we have any questions, Victor? Okay so here is the aneurysm that's being exposed through the Sylvian fissure. It's relatively sizable aneurysm, and we used the microsurgical techniques to go around the aneurysm. In this situation, it will be very preferable if possible, to go along the anterior part of the Sylvian fissure identify the M1 but unfortunately the M1 was going more medial and therefore our best chance `to identify it was by mobilizing the aneurysm more anteriorly and identifying that M1. This is a very simple application or example of using ICG. We try to obtain proximal control of the M1 branch. Again, micro deception allow release of the aneurysm from the surrounding into structures. And you will momentarily see that the M1 branch is exposed along the neural ocean of the aneurysm. A temporary clip is subsequently replaced. And we'll go ahead with the clip application. In this situation, we thought a current clip would be at least in the option. The initial clip was used. The second clip was used because we felt the initial clip was a very long one. And what's for signaled with a second one would be useful. And as you can see here, it shows that the aneurysm is well clipped. Again, this is the ICG the into branches are patent. And if I remove this distal clip, the smaller clip, as you will see in a second, the aneurysm fills up. So it tells you that that second clip was really important in assuring that the clip was, or aneurysm was penetrating. Let's go ahead and go to our other case here. This is a post-operative angiogram from the same patient. Again, confirming would open penetration of the aneurysm as was indicated by ICG intra-operatively. Let's talk about a 43 year old male with a sudden onset of headache, subretinal hemorrhage. And this is an interesting case. It's not a traditional saccular aneurysm. Actually he was diagnosed with a left fusiform A1 aneurysm. This is the CT scan this is the angiogram. Again, the CT angiogram was somewhat confusing. Subsequent 3d reconstruction of the cerebral angiogram revealed this dilation of the A1 branch. Approximately again, this is internal carotid artery. This is a one on the left side with a fuse and fusiform A1 aneurysm and a true branch. Let's go ahead and have a look at the surgical video and see how this surgery and ICG helped us make some decisions. Again, this is the left front temporal craniotomy. You can see that this is the left optic nerve, right at the tip of my arrow. And these are micro scissors, which we're gonna use in the second to open the wrack nerves over the optic nerve. We have an excellent question from one of our colleagues and he's asking if we do actually perform pre clipping ICG? I do not. Remember if you do a pre clipping ICG, the dye is gonna stay in around 20 minutes and you cannot do an adequate ICG to assess things because everything is gonna fail. So we don't do that. Here is the, again that fusiform aneurysm, as you can see at the tip of my arrow, and I'm putting it clipped, I think in this circumstance a permanent clip, because we decided that we're gonna go ahead and trap the aneurysm because primary clipping was not possible. This is the section along the distal part of aneurysm again showing the distal part of A1. And you can see ICG shows that the umbra is open. That's very important. And it shows that A1 more proximally open, as you can see here. And the aneurysm is filling as you can see here, but it's very much slow flow. And that was a good indication that distal vessels as you can see here, more distally are filling. And so the aneurysm is filling less. It shows that the degree flow is much less than the aneurysm and the surrounding vessels are patent. And I think that was very important information in terms of knowing that at this juncture, no further intervention was necessary. And again, critical point is that the surrounding important vessels are patent this is a postoperative angiogram showing no evidence so stroke on the cordate or the distribution of the angio huebner. And again shows complete arbitration of the aneurysm by it's spontaneous thrombosis, two days after surgery. So again I see it was not only important to determine patency but it shows degree of flow in an aneurysm that we wanted to thrombose more spontaneously. Let's talk about another difficult case. This is a 66 year old female with sudden severe headache and the questionable subarachnoid hemorrhage. And it is really shows a right partially thrombosed distal MCA aneurysm. As you will see in the imaging modalities so here you can see the MRI that was performed prior to our transfer to our institution. And you can see this distal MCA flow void. The CT angiogram clearly shows an aneurysm very broad based and a further 3d CT angiogram revealed again, that this ends is very much involved the vessel itself, and there's really no clear neck. There is a vessel that goes in and a vessel comes out, and this would be a place where potentially a bypass would be indicated. So let's go ahead and look at the surgical video in this situation before we'll look at the post-op imaging and here you can see right sided approach and you can see, I'm sorry, my video jumped over a little bit, my apologies. I'm gonna go ahead and bring my video to its appropriate place and we can continue. Do we have any questions, meanwhile, while I try to proceed with this case, Victor, Okay, well this is the end of our last case. So we should get shortly to our next case. And actually that was our second case that we just went through. And again was the ICG from our last case, the second case. So here's our case. You can see a right sided approach and it shows that can you see the video okay, or not yet? Victor here we go. We can see the aneurysm was trapped. And then you can see that the distal end two branches feel in a second that actually in this situation, that the ICG made sure that the retrograde flow was adequate. And that's how we knew that in this case, we can completely ligate the parent vessel proximal and distal to the aneurysm without any sequela. So the aneurysm was subsequently opened in this case and a shorter decompression was completed. And again, you can see that there was really no good neck for us to reconstruct this aneurysm. And we turned our temporary clips to actually permanent clips. Anything to further deception shows that if we remove the temporary clip approximately there is still alive aneurysm. And again, permanent clips were placed and post operatively as you can see in the images here, the patient do not have any evidence of ischemia. As the retrograde was confirmed by ICG and the post-operative angiogram reveals retrograde flow through the distal MCA branch is filling in for the area that was ligated. Let's go ahead and talk about another case. This is a six year old female with dizziness who had an incidental about nine millimeter PICA posterior inferior cerebellar artery aneurysm. And again, these aneurysm are more distal. As you can see, the base is relatively broad. And in this situation we felt surgical clipping is most reasonable due to the broad base of the aneurysm. As you can see the aneurysm is located along the floor of the posterior fissure and let's go ahead and start this surgical video and have a look at and see what would be the way ICG can help us in terms of assuring aneurysm obliteration, and a patency of the surrounding vessels. Again, this aneurysm as you see here was approached through a suboccipital craniotomy. You can see the PICA going into the aneurysm and coming out again. This is the PICA that we're temporarily uprooting here. The cerebellar tonsils are retracted. The clip was placed parallel. As you can see to the direction of the flow in PICA the first clip left some dog here, as you can see more distal on the aneurysm neck, and therefore a second clip was applied to assure the complete occlusion of the aneurysm prior to performance of ICG. And you can see the aneurysm itself looks a little bit blue right now, and here's a more sort of zoomed out view for you guys to see our approach along the posterior brainstem. As you can see the ICG momentarily, the aneurysm is occluded. You can see your clips here, and there's really no feeling beyond that. And the parent vessel is very nicely open. So this is really a quick way to ensure the PICA is patent the aneurysm is obliterated and no need for intra-operative angiography, especially in the situation patient can be laterally prom position. Let's go ahead and talk about our next case here. This is a postoperative again, Andrew Graham, we do regularly do actually this case. I'm sorry we didn't do a post-operative angiogram to confirm complete occlusion. Let's talk about a 60 year old male with a sudden onset of headache. And the imaging revealed evidence of subarachnoid hemorrhage. He had this almost blister like small aneurysm off of the Acom. This aneurysm was clipped surgically and post-operative CTA and intra-operative ICG revealed complete occlusion of the aneurysm. However, again as you can see, even the ninth angiography revealed no residual aneurysm. Unfortunate he had a severe headache on the 21st day. And as you can see, he had a pseudo aneurysm forming at the neck of the previous aneurysm, really much larger. And this sorta aneurysm obviously is a very challenging and he was in to treat surgically let's review this surgical video. This is a very interesting case. This is a right frontotemporal craniotomy. You can see that the approaches, obviously some frontal, this is the old clip that you can see at the tip of my arrow. These are the temporary clips that were placed on A1 bilaterally, and here is putting a finished straighter clip across the neck. And you can see the aneurysm right there. It's a very thin wall almost there's no wall to the aneurysm, what we would expect in a pseudo aneurysm. And here it was really difficult to get a neck with preserving the Acom we had to remove the clip a couple of times, as you can see in this video to assure that the clip is really causing no stenosis of the Acom as well as preservation contralateral, A2 as you can see the clip is being moved, just add more anteriorly. And now the A1 and the other A2 on the other side is gonna be more in view, as you can see in the tip of my arrow. So this is a pseudo aneurysm a difficult situation. You may have to remove your clips multiple times, and you really wanna have a quick feedback of pseudo aneurysm completely a true trader at least somewhat, has a low flow where you can keep the A1 patents or Acom patents because the neck of aneurysm was really incorporated the entire segment on the Acom and therefore postoperatively, it would spontaneously thrombose. And as you will see in a second, we use the ultrasound here and we went to ICG and you can see the ICG show, some flow in the aneurysm, very faint, but all the vessels are patent. This clip was ultimately repositioned to ensure, complete occlusion after the pseudo aneurysm which is more important when secured. And as you can see, you see a very bright flow, but a very faint flow in the aneurysm right there. And again that told us that this area was a most likely will thrombosis. And this is the shoot there right here, the aneurysm itself right there, and that we found very helpful in terms of assuring that this aneurysm would be excluded. We did not feel a primary clip and complete occlusion of the aneurysm trap was possible without preservation of the Acom. And so I think as you can see, this is the one of the further results of the position to clip. This is again A1 trial at it behind my ultrasound in pro micro graphic ultimately this aneurysm thrombose post-operatively. Do we have any questions, Victor? Okay, let's go ahead to our last aneurysm case and this is actually the final result from this case in the pseudo aneurysm shows that the Acom was relative to patent. And this is a six months CT angiogram revealing that there was no further development of the pseudo aneurysm and acute occlusion of the previous vast formalities. 36 year old female with a sudden onset of headache, usually subarachnoid hemorrhage and a very interesting aneurysm this is an anterior choroidal aneurysm And as you can see here, the Pcom right there. This is a surgical view showing the anterior choroidal artery Pcom the aneurysm, therefore it's distal to the Pcom or takeoff most likely is an anterior choroidal aneurysms. And this surgical video shows, and again, these anterior choroidal aneurysms can be often very challenging. And you can see this as a left sided. I'm sorry, a right-sided frontotemporal craniotomy and temporary clip has been placed on the proximal ICA. This is the aneurysm, very broad based. You can see that anterior choroidal right or posterior tip of my arrow and we really wanted to put a clip and very quickly assure that the anterior choroidal arteries patent because it's sacrificed, as we all know has significant consequences, and here is putting it in a straight end of clip across the neck parallel to the anterior choroidal artery. And in these broad base aneurysms, I feel it's really important to put the clip parallel to the vessel anterior choroidal arteries rather than the traditional clip placement. And as you can see the anterior choroidal artery is patent this is a higher view of it showing my sector, anterior choroidal is patent and it's important to have an ICG and immediate feedback to see is dismissal actually patent. And as you can see here, it is patent There is no residual aneurysm. And again, another way to identify patency of these running vessels using intra-operative angiography. One of our colleagues is asking, what is the dose of ICG or injection? And unfortunately that skips my mind. I'm happy to answer that question. If they send me an email, I'm gonna leave my contact information, or you guys can obviously reach Victor Chan, who is a representative from Zeiss and send him an email. He's gonna leave his email for you in the chat function and therefore can be reached for technical questions. Again, this is post... This patient actually not only went on underwent ICG has an intraoperative angiography that again showed and confirmed that the aneurysm completely occluded and no evidence of postoperative ischemia in the distribution of anterior choroidal artery. So now that we exhausted all the applications for any reasons, well let's touch upon how we can use ICG for arteriovenous fistulas. These are a class of escalations that are on the special interest to me. And let's discuss a case of a 72 year old male with a sudden onset of left upper extremity weakness, which resolved over one month. And as you can see on the images he had this hemorrhagic, so somewhat calcified lesion in the right parietal area, therefore because this was a spontaneous hemorrhage and angiogram was completed, and you can see the internal injection shows no abnormality. And that tells you a lot because an external injection is critical. If the internal is negative and you can see how impressive external injection on anterior choroidal artery reveals its very large parietal or intravenous fistula with a very large variances on the cortex. So let's see how we can approach this intravenous fistula techniques were not deemed very adequate and definitive and therefore this patient underwent surgical exploration and the surgery was performed through a right parietal craniotomy. As you will see in the second. And this exposure, you can see the superior sagittal sinus are retracted with sutures. Again, this is two vessels that is, you can see going to this malformation, but it's hard to know which one is the fistula. As you will see, there's two vessels here, one next to each other. And that's what we do then ICG. And you can see this is a vein this is the fistula. And this was the use of ICG in terms of delineating artery versus vein. So you can see the bright flow in the artery right here versus a more delayed flow. As you can see on the first injection when the flow came in and the dye came in and that was a guidance for us in terms of helping us identify the fistula. Ultimately the fistula was further dissected off of the folks. As you can see at the tip of the arrow using microsurgical techniques. And again the fistula has a much more study and robust wall compared to the vein that's been retracted with a suction. And one of our residents, Dr. Dan Kim, as we'll see in a second is gonna go ahead and place the clip across the fistula that as you see is entering the superior sagittal sinus. Again, this is the official completely dissected around it and getting ready to receive the clip. Again, I think I'm trying to show other vessels that are going around the fistula, but the fistula remains to be the one that is entering to the sinus or duo sinus. Do we have an extra question about what kind of work in distance and magnification we use? To be honest when the moment you set oscilloscope to do the ICG, it zooms you out, but then I zoom it in exactly where I want it to be. And then I asked them to inject the dye. So I use it at any magnification I would like it to be. And here is you can see Dr. Kim, one of my residents placing the clip across the fistula and obliterating the fistula. And more importantly we're gonna do an ICG to make sure the fistula is completely excluded. So I think for different lesions, you should try to use the magnification on the microscope that gives you the field of view that you like to see. And really depends how big you field of view is. Right now field of view is very large compared to the aneurysm cases we presented therefore I zoomed out to be able to see the whole structure. And you can see there's no dye coming in into the malformation. There's some thrombosis from the previous dye that pre treatment or pre clip application dye. And again assured that this malformation was completely excluded. So again, this is an application for choroidal aneurysm not only for diagnosis of the fistula before treatment and clip application, but also after the lesion is excluded to confirm appropriate clip application. Let's go ahead and review our next case. And this is a 36 year old male with a sudden onset of severe headache, nausea and dizziness. Again, this patient was diagnosed with a right tentorial fistula. This was a CT scan on admission, MRI showing T2 signal change of evidence of hemorrhage in all the studies that are present. We went ahead and did an angiogram and you can see the fistula from the anterior choroidal artery along the area of the angio benescoli tensionary along the tentorial. This is where I usually the superior control Sylvian is creating a large barracks in potential space causing venous hypertension, leading to evidence of hemorrhage in the brainstem and therefore the presents symptoms on the patient. This is again a CTA reconstruction showing the abnormal connections. Let's see if the video will help us here. This is a right sided, suboccipital retromastoid craniotomy for a dissection and identification of the fistula. As you can see, the fistula is located... This is the fistula right there at the junction on the pietras tentorial junction. This is the initial clip we tried to put a straight clip on subsequently changed our plan. This is the fifth nerve, and this is the seventh and eighth cranial nerve tentorium again is up there and this is where superior petrosal vein usually is located in here is went ahead and quickly put a what we'll call a vein edit clip to ensure that this connection is complete and here you see the swollen vein and it always worries you, what is this? Did I click the wrong vein? And a quick ICG would be very helpful in order to assure that the lesion is excluded. And so again, the lesion sitting right in the hood entry zone of the trigeminal nerve, and as you can see the ICG there is no filling of that ugly looking vein that swell up after clip application. This is a superior cerebellar artery at the tip of my arrow. So this was a quick way, and again shows the fistula, but the fistula really doesn't go anywhere past the clip. So, and again, this is the vessels along the brainstem and it into vessels around it, seven and eight are complex. So let's go ahead and discuss one of the options for aneurysm formations. And here is our next case shows. And again, this is a postoperative image of that fistula along with the tentorium Elvis, the reason that would result. So what about arteriovenous malformations? How about a 36 year old female with headache and light trial AVM? And here is the MRI, MRA, and you can see to the large size of the arteriovenous malformation, and you can see again, further angiograms evidence of the arteriovenous malformation. We go through this quickly. Again, it was partially thrombose and you may have already seen part of the video and the video clearly shows the veins and arteries and can help you on the surface of the AVM to delineate what is AVM, what is not? This is a second case of another arteriovenous malformation in the right frontal area, which we removed. Again, this is the life low is the midline. And you can see the vein and the arteries. We did not perform a pre resection ICG in this case and continued to remove the AVM. As you can see, this is again, the posterior deep part of the AVM in the white matter and where the AVM resection is often most difficult. And we got into some bleeding and to make the presentation exciting we thought we show some of the challenging parts of resenting this AVM and obviously patients in the AVM resection always comes handy. We had again, this is the far low, this is the interior part of the AVM, this is the posterior for a low. And we went ahead after isolating the AVM anteriorly, or we might say in theory, this is the final resection cavity for arteriovenous malformation And again, in ICG shows in arteriovenous no residual AVM intersection cavity with normal vessels patent on the normal cortex. So this is really a simple application of ICG for arteriovenous malformation. And this really is the MRI of the patient whose images we just reviewed and discussed some of the new outside retrench using ICG for arteriovenous malformation. That was a surgical video. Let's talk about revascularization. How does ICG help with cases where we need to do bypass? This is a 61 year old male with a history of bilateral carotid occlusions and multiple strokes. This was his CTA again revealing there was no flow into cranial through the bilateral carotid arteries. This shows a reconstruction of this official temporal artery revealing the entire branch is much more robust than the pridal or the front branch is much more robust than the pridal branch. And again, you can see, we use intraoperative CT angiography to identify a big cortical vessel that is very healthy and can receive our graft. So let's go ahead and talk about how to do a STMC a bypass and how can ICG help with this procedure? What we'll be seeing would be a left sided approach. Again a craniotomy has been completed. The cortical vessel has been prepared and again cortical vessel has the archery autonomy is being performed to prepare this side of a recipient. And here we've using the scissors to do the archery autonomy along the cortical and for branch again using the highest magnification of the microscope and here archery autonomy is relatively completed and it looks okay. Here's the STA vessel making the... And I'm trying to complete the first anastomosis suture after that's completed we're finishing our first note. Any other questions, Victor that I can help out please. What focus techniques do I use to optimize my picture? And this is one of the questions came in. Really that depends what procedure you're doing. I typically just try used the appropriate button on the handle of this scope to assure that the pictures obviously in focus and also adequate magnification is available. What's most important is that I tried to carry a vascular procedures at the highest magnification possible because it gives you a good lighting and lighting. It really allows you to do microsurgical techniques very well. And it really makes for a prettier image because you really have excluded all the distracting, all the distraction of distracting factors. Here you can see we're proceeding to complete the anastomosis with one side placing sutures or using 10 sutures here all across. This is finishing the anastomosis on the contralateral side. Some people may use nine oh, but I have found it to be helpful to use 10 out, although we can be much more challenging. This is the end of our really bypass showing really adequate suture placement. And here is the ICG showing very nice patent STA patent cortical vessel patent distal vessel. And then this is really important to get this feedback. Then USTA is booming. This is the dual closure. And then you can further confirm with your micro doctor This is a postoperative CT postoperative angiogram, really showing how the ST goes through the bony defect and joins really through MCA construct. And here you can see it's coming through the defect. And this is the anastomosis between the STA and for branch, really a very satisfying operation, obviously in very selected patients. Let's talk about a 41 year old female with a history of an MCA dissection about 15 years ago, suffering from a giant M1 and A1 aneurysm is really is not primary clipable. As you can see, this is senior internal carotid artery joining A1 and M1 and was in fuse form and involves both segments. And we felt that a high full bypass across the MCA would be reasonable with a ligation of A1 distal to the aneurysm because there was patent Acom. And let's go ahead and review this video of pre-operative high flow bypass. Again the bypass has been conducted on the right side, and this is in two branch. That is the in three branches and two branch, as you can see has already received the recipient. And this is the high flow graph. In this case, we used the vein graph. You can see the vein graph that's going into the fissure and ultimately being subcutaneously passed along the anterior part of the ear to external carotid artery, where a anastomosis between the vein graft and external carotid artery is being completed. After the anastomosis is completed as you can see to the external carotid artery, we'll proceed to restore flow again here removing clip instant clip, and this is the fissure obviously, and you can see an ICG and assure that your graph this patent and your MCA territory is patent. And as you can see, here we go, the ICG showing the patent graph, patent MCA branches, and really this immediate feedback showing patency of the vasculature, I think is very important for the surgeon to receive a confirmation of the anastomosis as adequately performed. This patient ultimately underwent proximal ligation or of the carotid artery in the skull-based just distal to the interior carotid artery. And again, we can go through different techniques of bypass, but I think at this time, for the sake of time, we'll proceed to further applications of this method ICG. And there are other applications besides if we're using an in vascular cases and let's talk about tumors. 62 year old male with a generalized seizure in bilateral frontal meningioma. This is his meningioma. It shows that the sinus is relatively occluded, and we don't know how far it's occluded. The MRV shows that it's way up there, but there is some drainage, some cortical veins that can be very important because that's the being a prologue. And in this situation, we felt that it would be a good idea to use intra-operative angiography to ensure patency of the sinus and the surrounding cortical vessels. And the cortical vessel more specifically. Here you can see the craniotomy which was by frontal. This is forks in cut away. This is the beta I was talking to you about right there, going to the sinus right there. And this is the residual part of the sinus. It's important to me with this vein is patent because you don't wanna sacrifice it if you don't need to. And in this case we went ahead and did the ICG and you can see the vein to be patent and it's actually going to the sinus. And therefore we left the portion of the sinus here intact with a small amount of tumor attached to it. So this is one way. Another way, this is a right sided Suboxone for craniotomy for MVD. And you can see there is a vessel here right next the nerve, the fifth nerve, and it's hard to notice its a nerve or an artery. Can I take it or not? It's really in sheath within the arachnoid and stuff, very visible. And this is again, mobilizing the nerve. And here you can see the vein has the same phase as the superior petrosal vein. And you can see that this small structure that we're questioning is most likely vein because it appear at the same time as superior petrosal vein. And so, again, this is one way to identify veins versus arteries by when the dye shows up in the unknown vessel, compared to the surrounding structures that you were sure to be vein or an artery. And again, ultimately we decided not to take that vein because it did have a dupe that went ahead and on along the entire brain stem. This is a another case where there could be some pitfalls to ICG, and we would like to review those, because I think it's important to realize that although ICG is a great tool, it has its own limitations. This is a 55 year old female with history of headaches and incidental 1.6 R MCA aneurysm, and she underwent surgical exploration, as you will see here. And first of all, let's define the lesion. You can see the MCA coming in here and very broad base large aneurysm, and in showing portal incorporation into branches. Well in surgery, there will be multiple clips placed. You really wanna short patency of the vessels. And here is what we did during surgery and what we felt ICG maybe in this situation would have done better. This is the first clip that was placed. And I'm gonna go ahead and make sure we reach the white part of the video. I apologize, again, some of the videos can have been mine of their own. We initially placed the clip, as you will see in a second across neck of the aneurysm. Here's the clip that he was seeing, the second placed across the neck of the aneurysm. And this is the M1 branch and here you see it's patent. It goes, and these are in two branches on its sides, showing how the current vessels are patent and the Henry himself looked really not filling in ICG. And he was using ultrasound and you just have aneurysm filling. And so, even though the other vessels are patent we felt like there was just something wasn't right. That even the ICG was telling us the aneurysm was no filling. This aneurysm could be filling somewhere. And therefore we put a finished straighter clip due to the very broad base of the aneurysm. And as you can see here, I'm trying to place this clip across the more distant part of the neck. And so we thought the ICG is negative. We put a third clip, he felt very good about everything. And let's say well let's go ahead and penetrate aneurysm with a needle. And you can see the blood coming out the aneurysm. So even though the ICG was not indicating any flow, there was a flow into the aneurysm. And therefore we had to remove all our clips. We refashioned the clips with a more distal application. So there was no residual neck cross distal edge, and eventually this aneurysm was completed or obliterated without further flowing aneurysm as you can see. So if the aneurysm is very atherosclerotic has a very thick wall in this situation, you may have a hard time seeing what's going on inside the aneurysm with ICG. And as we say, there's no perfect method. There's no one method that can replace every hunch of a surgeon or every decision and make the final decision. You really have to be careful how you use the ICG in order making a decision. If the vast collusion has been excluded. And this is the post-operative 3d angiogram showing that the aneurysm was completely occluded with no residual neck across the aneurysm. So I wanna thank all of you guys for joining us this evening. I know there were a lot of cases, pretty much going through them very quickly, try to indicate really what are the indications and pearls and pitfalls for use of ICG in improving the care of cerebrovascular patients. So I wanna thank you again all of you guys for joining us this evening and give us your valuable time.

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