Grand Rounds-Complication Avoidance and Management in Cranial Surgery

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- [Dr. Aaron] Good afternoon, ladies and gentlemen, thank you for joining us for another session of the 3D videos for operative techniques. This one is mostly focused on complication avoidance and management. Our speakers are Dr. Robert Spetzler, Dr. Michael Lawton, and Paul Gardner. I'm going to start with some of my own videos, and we'll go ahead and proceed in that order afterwards. We're gonna go ahead and have all the faculty sort of start from downstairs so this way we can use the laser pointer to be able to show the video as it goes on. Again thanks for joining us. So I'm gonna go ahead and start a video of mine. This one is a PCom aneurysm that intraoperative ruptured occurred before we were able to secure any proximal control. You can see it's a relatively large aneurysm with a lot of blood on the right side, relatively broad base, we went ahead and started the microsurgical dissection of the sylvian fissure. A lot of blood, very adherent. By the way, if anyone can sit in the middle role, you will see that's a lot more attractive. Here as we started to elevate the frontal lobe the brain became very sort of tense, you can see you get intraoperative rupture. And why I have not secured anything sort of approximately at the level of the carotid. Unfortunately, the brain is so hard that you've seen my suction started shaking, that's not for any other reason besides the fact that the brain is so swollen, that the force that I require to keep the brain open is almost taking over the strength of my fingers there. And so I'll start using a retractor again, the brain is too tough to handle, and I'm trying to somehow reach down there, I try to ask for adenosine, you can see the temporary clip aint gonna go there. Again another try. No way the brain is absolutely too tense. So we'll go ahead and do the command operation here and start removing some brain around the aneurysm. Just follow the flow of the blood, be able to see where things are. You can see eventually the old blood is gonna break through. You're gonna see another suction coming in and so the brain is getting more tense. The biggest suction available comes in and we just follow the flow of the blood. Thought about doing adenosine here, this is not our regular anesthesiologist. And at that time, that was not an option, unfortunately. So we go ahead and use the retractor. Interesting enough, we're able to put a temporary clip. And when I removed the temporary clip, it was no longer bleeding again, and that's just what's very peculiar to me. We'll go ahead and expose the aneurysm neck, relatively broad, you can see there's no temporary clip. This is gonna go off a couple of more you'll see during the video without proximal control. I try to minimize the use of it unless absolutely necessary. Just go ahead and create sort of more window between the inter choroidal, and the find the PCom there. We'll go ahead and start putting a temporary clip, because I wanted to really save their PCom if that's possible. Although there was a good P1 here, so it's preservation not absolutely necessary. You can see it again, that inter choroidal goes off again. This time am really getting tired of this aneurysm going off four or fifth time during the case. We'll go ahead and put a curved or angle clip parallel to the access of the carotid and that's pretty much really important to be able to really use the mouthpiece and work around the PCom to hopefully be able to preserve it. We reposition the clip once again and did a fluorescein angiography. As you'll see the aneurysm does not look Peyton, in other words it's occluded, PCom is filling, everything looks good. And here's the choroidal, however, unfortunately, as it's been my experience and others, this can be a false recording. Here is I put a needle into it and the aneurysm still alive, obviously not very aggressively bleeding in this situation, a finished story clip, obviously ideal as it's coming in right now, again, parallel to the other clip. And that usually takes care of business. I use ICG or flouricine in tandem, so I don't have to wait for one to clear. And we also use the 800 flow, and you can see that it looks like as if the PCom is filling at the same time but it's actually delayed, and the delay shows that I have already sacrificed the PCom and it's filling from the posterior circulation, and that's the post-op again, confirming that the PCom was gone, but again, the patient did fine because of a good P1. So intra-operative rupture 52 year old female. You can see that this is an aneurysm that is A-comm, and I think there was an error on my side in this case to go through the eyebrow incision because this aneurysm was more pointing maybe a little bit more posteriorly than I should have. We go ahead and removing the rim would have been a nice option here. However, I didn't feel as long as I get a very flat trajectory that may be necessary. We went ahead and open the dural and one of the errors that going back I should have definitely done differently is I put a temporary clip, you can follow the sort of the view if you wish. The temporary clip was on, but the space is so little that as I started second the temporary clip comes off, I still manipulating the aneurysm and the sector perforates the neck of the aneurysm. And that's really unfortunate through this small trajectory because you really have very limited options when you get into trouble in our eyebrow incision. So you will see there A1 we'll go ahead and place a temporary clip on it and I get this false again, this the aneurysm, I'm gonna remove just tiny bit amount of jives shriek this in this case in the aneurysm is almost pointing a little bit superiorly and not maybe that's a contralateral A1, pretty comfortable. You see the temperate clip here, but I make sure it's all the way across. And then I'll go ahead and start playing with the aneurysm, just about now the clip is completely off however, I'm unfortunately making a mistake and not the reason it's is hard and I'm feeling well, maybe it's feeling from the other side, that's why, but I'll start pushing more than I'm supposed to having unfortunately feeling that well, everything is under control. You can see the aneurysm was punctured. Brain starts getting into tiny stains because there was blood going on the other side. The best situation is not to sort of panic, even though your space is very small and just try to see where the bleeding is coming from. The other challenge here is as you can see, the window's so small, the mouthpiece is truly life-saving in this case and really a gift of God. So we'll go ahead and I do not see contralateral A2 so placing it to permanent clip is not wise. I persist on trying to find some landmark, unfortunately that's not feasible. The error again here was that I did not go back to look at my temporary clip in the middle of all this torrential bleeding thing, should follow the tenants of vascular neurosurgery. So I'll go ahead and think of a creative way to get more space to look around, we'll go ahead and put a straight clip, not as a permanent clip, just for me, be able to deflate the aneurysm, to be able to look around and knowing that I am bleeding right now, I don't see anything, but this is just a tentative clip to give me an ability to look around. You see the bleeding site right there? And you see A2 just about a hint of it. This is nice because then I can just move my clip more posteriorly, right at the location of the bleeding, and that should stop all the bleeding and let everyone relax in the operating room and just that's about all. After that you can obviously inspect the A2 artery hat you see there and make sure the clip is sitting nicely. Here is the clip that was off their entire procedure, which I had not checked on a little bit more carefully. And interpretive again, ICG, it's not very effective in small corridors where we cannot get enough light for the problem of chromatic aberration. Here is another view of the ICG in very limited spaces is much more effective, this is the final result and again the key in this situation was to follow the tenants of vascular surgery, even with errors because it's the post-op angiogram, the 3D looks very good. Thinking about creative ways to create space for yourself to see around rather than start putting clips in very recklessly. How do you like it?

- [Dr. Robert] Oh no, no, no, Aaron, I think you handled that very well, but a couple of points. I don't understand why you would put a temporary clip on the A1 that you've got beautifully exposed. If you wanna gonna use a temporary clip, it should go on the contralateral A1, so that if you do have a rupture, all you have to do is put it on the ipsilateral AI and you would have complete control.

- [Dr. Aaron] Correct.

- [Dr. Robert] Second, when you dissect it at aneurysm down, I was exactly afraid of what you will do, because it was obviously adherent to the contralateral A2 and pulling it down. And the only reason I knew that that it was a risk because naturally that's happened to me, and there's almost no complication that I haven't had. But we try to avoid. But I think the principle here really should be, you had adequate exposure, but the temporary clip, first of all it was too long, it should be very short so that it doesn't get into the way of your manipulation, but it should have gone on the contralateral A1 so that you would have had complete control over the a but nicely handled after that.

- [Dr. Aaron] It's better to be lucky than good. I think that's a very important point. I can tell you that that makes very good sense. My reasoning was, I'm not sure if it was right or wrong, is the dominant A1 was on the left, it was much bigger, I thought that's better given better control. I get perfusion through the contralateral smaller A1, but again, it's much difficult during the hemorrhage to get a contralateral control, and that may be a safer way just the way you mentioned it. But I appreciate the comments, I think that's very important especially for the audience and myself. Kido you mind before we start the next video, Kido can you hold off? I wanna take a moment and thanks Meditech for being such a leader in neurosurgical education, the videos you see today would have not been possible without the assistance of Kido Hattendorf from CIS was sitting back there. And he's not only helping with this session, yesterday all the practical clinics truly CIS have been a great partner to make these possible for us. So I wanna personally on behalf of all the faculty, thank them for their time and effort. Kido, would you please go ahead? So this is a 42 of man female with a 10 millimeter arthroscopic aneurysm. It's a right MCA. Again, these are aneurysms, we still have a chance to surgically tackle without much criticism from our endovascular colleagues. They're just standard exposure I like high magnification, just like our other colleagues in the panel use. That's one of the advantages of microsurgery, I often see some of my colleagues doing microsurgery under microscope. So we go ahead and I couldn't find M1 anteriorly, we go ahead and come more posteriorly, the sect around the aneurysm, neck and dorm a little bit find the M1, you see the lateral then to constrain arteries that obviously have to be protected as we put a clip across, and here is the aneurysm, we try to open the rack node membranes widely to be able to avoid fixed retractors Again, this is just the antraport of fissure, so I think entered temple artery, enjoyable part of surgery. And I know that's clear for all of us, but I think often at least my fellows and residents try to jump in too quickly. So here's the aneurysm, you can see it relatively nicely in the view, in 3D it's almost enjoyable. You can see that frontal branch, we'll go ahead and disconnect the aneurysm unruptured aneurysm, to be able to see all the way around it. I go ahead and put a curve clip on both sides, it's relatively large, I didn't feel it was as easy to put a single clip. Again, I use the ICG and floor scene together because here you can see this, this is feeling retrograde. I may have missed that just in an ICG because you don't use the oculars as much. And so this gives me an idea that this clip is probably too close to the neck, we'll go ahead and reposition this clip, which would take only a few seconds rather than waiting for fluorescent or ICG to clear, we'll go ahead and do ICG now, again, it adds a lot of efficiency and this is a big aneurism, we'll just add a few more clips just to be safe, and here's the reasonable results in relatively large aneurysm. Any comments Dr. Spetzler

- [Dr. Spetzler] No--

- [Dr. Aaron] Thank you. So I'm gonna go ahead and show a case that's a Cushing's disease at 43 are female. This is a 2D obviously, we just don't have an endoscope that's very effective in 3D. I wanna have you pay attention, this is a macroadenoma large and you'll see it's pushing up anteriorly. We'll go ahead and do an extended transfer approach. I can have Dr. Gardner comment on this maybe at the end, we'll go ahead and remove the tumor, whatever we find a cellar. This is tuberculum up there. Really an enjoyable operation, one of my most favorite operations. And with the endoscope, I just can't be more aggressive. And here's the results. Everything looks really clean, we can sort of irrigate and look through the underwater and really inspect very well without the blood, and we felt that we really have done a nice job, and I'm gonna ask Paul to comment on this. Paul, this looks pretty clean, at least what I thought you can look here, there is no residual tumor. I go ahead and open the dural a little bit more superiorly just to make sure I haven't missed anything over the tuberculum, and you'll see momentarily the optic nerve comes in view, everything looks really nice and clean, I even look above the diaphragm I don't see anything, and I assume most people all would have closed by now. However, I have always learned in these macro adenomas, when they're functioning, you gotta be extremely careful because gross total resection is important, you see the optic chiasm there, everything is clean. And then I put a little tiny ring red in there and something looks suspicious. I go ahead and look closer. Well, I'm not sure what it is. And here look down the second away, anterior to the optic nerve and here is tumor. And this I wonder is one of the reasons for our failures, you can see the optic nerve as it's entering the canal, here's a nice view, closer with a 30 degree endoscope. And in this situation obviously you have to start opening the diaphragm and dissecting, and you can see how much microsurgery you can do with a 30 degree angle, the optic nerve next to you using angled scissors, it's been one of the criticisms of endoscopic surgery that microsurgery is not as easily feasible, but I do believe with angled instruments, anything is possible even very close to the optic nerve, using the same microsurgical techniques we use through our larger openings. Here's the optic nerve, here is the tumor. This tumor is actually above the chiasm. We'll go ahead and use a ring curette angle, using a 45 degree endoscope, dissect the tumor from A2s that are gonna come into view. I could have potentially remove more to a bone to look at, but I thought it's a relatively soft tumor, and you can see the chiasm, you can see the optic nerve, everything is in nice view, and it's really beautiful anatomy from downstairs. And you can see the rest of the tumor will come out, while this is going on I wanna get the opinion of Paul. What would you handle this here differently?

- [Dr. Paul] I think the angled endoscope obviously is key for this. I tend to overexpose, so remove more bone, do a transplant them approach, et cetera. You know, when in doubt always with this approach, you actually need more room than you do. It's more invasive from that perspective than a microscopic approach. But obviously, I mean, you follow the tumor and that's how you ended up finding. I tend to use angled suctions. There's a couple of malleable suctions that you can really angle upwards quite a bit rather than a curate. But an angled instrument that you feel comfortable with is what matters.

- [Dr. Aaaron] I was just interested that it looked all clean, and it was all above the diaphragm. It tells you that interoperative MRI, although I don't use the regularly is probably best for recurrent tumors and pituitary macro adenomas that are functioning. You can see the A2s, the chiasm, and the post-op MRI shows a reasonable result the usual fat, I don't really use fat for expanded one. In this case we really expected this just to be a regular pituitary but it turned out to be more than that. And she actually got a pretty good cure. And I believe that's my last video, unless I'm wrong, here we go.

- [Dr. Robert] Pleasure to be here to share some of my cases with me. I also wanna echo the appreciation and Greedo for making this possible. Go ahead, Greedo please. Here, we're talking about an AVM that's sitting right here. You can see it down in the gyrus. When you look at the angiogram, it's a poor one for embolization because it really has vessels on passage, it's coming up from the angular branch and you see it here. And here we're looking at the cortex, we're doing an ICG which really doesn't show us much. Redo the flow map which gives you absolutely beautiful worthless picture. And then open the gyrus, sorry, size. But I think the whole principle of the AVM, as you know, I'm a big believer in not using rigid retraction because this is an AVM that really has a major feeder, it's really ideal for putting a temporary clip on, and then taking branches only when I can see that they are directly going to the arterial venous malformation itself. And so really just going around and checking the vessels, separating those that I clearly see using temporary, and here's one vessel on passage if you follow it, it comes out and then it goes back up right along here. So then we get the branches from that And doing nothing more than using the non-stick bipolar. The non-stick bipolar with irrigation are just spectacular for this, because you really do not have any sticking whatsoever. And so here you see the one vessel on passage. You see the major vessel, we're going down deeper. They're obviously always much more extensive than we appreciate from looking at the angiography and the MRI scan. Here's the separation between AVM, you can see the large vessel, which then goes into the draining vessel, and we just continue right along the edge of the arterial venous malformation. And really just using the two instruments, the sucker is really used for suction but equally important as your disector. And because you have the eyedrop suction on your fingertip, you can really turn off suction completely with just moving your finger a little bit, you have exquisite control, I think that's really key for a suction, not unusual to have these little vessels down deep that you really have to chase. I do not like to just put tampa nod on them, I really like to follow them with the bipolar until I get enough of the vessel wall between the edges of my bipolar, so that I can coagulate them. And then taking off the temporary, that's the large angular branch. And if you look at the angiogram, you see vessel on passage vessel on passage, all pre served, and this patient had no deficit at all, even though it was really in the middle area. I left a little blood behind so that you could identify where we operated. Thank you for some of you being awake. So this is for an arterial venous malformation that is really right adjacent. I believe it was Cameron or Felipe that embolize this, this is what was left after embolizations, still significant AVM. So what I'm doing here is I'm approaching, and from the contralateral side, this is the ipsilateral side which I've opened, so the sinus is right here. And the only thing I'm gonna do on the ipsilateral side is to make sure that it's separate from the faux, I'm putting a piece of gel foam there to separate the AVM from the faux. Then I'm going to pull the dural over to the side of the AVM and then come in contra laterally and open the faux. The reason for that is for using gravity to retract the right hemisphere. And we are protecting ourselves contra laterally with the gel foam, then opening the faux widely, and that gives us the very best angle to the most lateral aspect of this arterial venous malformation which is going to be the most difficult. And then again with that same motion, utilizing the non-stick bipolar, the irrigating bipolar. In this case because of a so far away, we use the light at suction, which it gives us a better view down low, and then just continuing to go lateral and lateral let that steep angle that we've provided with the light from the suction really giving us excellent visualization of all the small vessels. Putting a clip on and this we could see, I thought I was done, but he could see the vain getting bigger and bigger. So taking the clip back off and continuing our dissection and finding a few more vessels And now this time occluding the vein and nothing changes. So we're gonna sacrifice the draining vein and then cut. If by chance the vein was already sacrificed and you had the AVM blow up, a very good trick is just to put a hole into the vein that you've occluded so that it can drain out, which will allow the AVM to collapse and you can continue to dissection. And that's the AVM. Here you can see the post-op AVM it's nicely done. This is for unruptured PCom aneurysm. You can see here and anterior coronal, so PCom and anterior colloidal, the exposure. And just as Aaron really showed very nicely in the last case is that you want that so flat, that's really the advantage of the modified OSC is basically you're just taking off the top of the orbit so that you have nothing in your way internal carotid artery. And as we look at it, optic nerve over here, portions of the posterior communicating artery, here's the aneurysm part of the aneurysm opening the arachnoid further. And so you see aneurysm here very thin walled, this is the aneurysm from the anterior choroidal right here, looking at the anterior coronal artery itself, and then the PCom aneurysm. Separating the vessels from the PCom, I really do not like to sacrifice the PCom. Separating the vessels from the PCom from the dome, and then here you can see by itself, this aneurysm is a firmly embedded in the tentorium. So as usual, I cut the tentorium and then I separate it from the third nerve. You can see here the red stuff has blood, that's not so good. An attempt at direct clipping is not so good. So temporary clip proximal on the internal carotid artery. I thought maybe that was enough to try another attempt at direct clipping was not, so a temporary clip on the internal carotid artery past the PCom. Now naturally the PCom as you could see was fairly large so by no means, is that gonna stop the bleeding? And you can see the counter traction from the sucker device as we apply the clip that gives us a chance to look. We see PCom separated, all the branches had to readjust that clip so that we made sure that the PCom was completely free taking off the temporary branches. That little piece of the aneurysm that had to be preserved because of the PCom is then obliterated with another small additional clip. And then finally clipping the anterior colloidal with obviously the most important aspect to keep the anterior colloidal intact. And here you see the anterior colloidal right here. And when you do the angiogram, you can see that in fact, it is a completely patented. So another nice example of a rupture in a small space, but really readily controlled. I think the biggest secret with when you have an aneurysm that ruptures is you don't wanna tamper not your opening because then you force the blood into all the subarachnoids spaces and the brain will come out at you. As long as the blood is coming out at you, nothing's going to really swell up, and that gives you a chance to get control of the lesion. And here you can see nicely obliterated the two aneurysm that I showed you. This is a third ventricular thalamic cavernous malformation. I showed you one yesterday which was a really readily, this is really right by the aqueduct interhemispheric approach. Again, the head is horizontal so that we're utilizing gravity. We're allowing the hemisphere to fall down, we're gonna use this trajectory going between the anterior cerebral arteries to the corpus and really utilizing image guidance to help the extent to which the corpus callosum has to be opened. Now, looking down, we see the choroid plexus. I like to open the colloidal fissure laterally to the choroid plexus rather than medialis it's described in most textbooks, because that way the choroid plexus really helps protect the fornix. So you have choroid plexus between you and the fornix instead of dissecting right at the edge of the fornix. Great respect for the fornix. And so we get down into the third ventricle. This time we have light at bipolar, which is a very nice way to get light in, the disadvantages is that the bipolar is not always in the field. So I've switched to the light on the end of the sucker. And then you can see the cavernous malformation being removed a piecemeal. Very, very small space, very, very small opening, but an adequate opening, and that's really the key. And sometimes naturally these cavernous malformations have a very large veins attached to them, and that requires a tampa nod it requires occlusion of the vein that is part of the canal, and then important to protect the venous anomaly which drains normal brain. So here you can see very nicely how the choroid plexus is a medial protecting the fornix. But again, no retractors required. These can now come out in pieces. You can see the different agents of the blood. And then before we leave spending quite a bit of time to make sure that we have gotten every piece of cavernous malformation that we can identify. And there's the overall view. Sagittal sinus, and here you see the post-op or the cavernous malformation was to the third vent. This was a contralateral approach naturally. this is a midline craniotomy for this cavernous malformation, which is like the other one except it's in the midline, and it's really sitting in the aqueduct, it's really sitting right at the end of the third ventricle as it enters the aqueduct. So we again do the same thing. Start off in a 2D as a comparison, here are the two anterior cerebral arteries opening. And now we're going to 3D looking down at the third ventricle, opening the third ventricle. I'm thinking we know that these images are reversed. Let's double check that next time for that part. So here you're looking at the aqueduct and you've got the cavernous malformation really sitting right at the edge, and then utilizing a little pituitary like instruments, mobilizing it, and then removing it. Here we have a retractor that's holding over the faux, and the septum pellucid so that it doesn't obliterate our vision. And here comes the carcinoid. And then picking really at the edges. And here you see the post-op, this is where it was right here. And it's amazing how you can do this without hurting the patient. A cervical ependymomata, see right here, the teaching point of this one will become apparent on the second usual exposure. This one is reversed as well. Okay, so now you're looking... What we try to do is respect the vain, so here you have the midline large vain, what I'm doing is really undercutting the arachnoid and be along the vein, cutting the branches that go over to the side that crosses the midline and then mobilizing that whole vein and moving it off the midline. Does that make a difference? I don't know how you could possibly be sure that it does, but it's sort of a nice principle of just pre serving veins. Just like when we were in the posterior fossa, we always preserve dandies vain or the veins with the middle cerebral artery approach, but you can see the medium Rafay easily identified with how the vessels come to the center right along here, and then opening the spinal cord, and then utilizing very gentle separation that really allows you to stay between the fibers rather than forcing them apart. And then the typical appearance of the ependymomata I think a key is again, that this is not a diagnosis you leave up to the neuro pathologist because unless they're very experienced and not unusual to get the wrong diagnosis, and if you think it was a glioma, you might not take it out, this is a surgical tumor can be cured. The feeding vessels and their majority come directly from the median Rafay anteriorly from the anterior spinal artery, some laterally as well and here you can see the cavity where the ependymomata was. Any questions?

- [Dr. Michael] So I'm gonna start with some aneurysm cases and just sort of give you some of my pearls for complication avoidance. So you can go ahead and roll this, and this is, I think I just want to talk to you about, on this one blindness, whenever we deal with an aneurysm like this, you wanna be careful of patient vision. This is obviously one of the toughest functions for patients to lose. So you really have to handle the optic nerve very carefully. So this is the view we're getting, looking down at the coronal process, this is the left temporal lobe, the frontal lobe is over here, and this is your standard intradural craniectomy. Here the cranial is coming out and you'll inevitably get a little bleeding from that perforation of the carotid ocular membrane. And that trick, which you saw is just injecting some TCL, which will immediately dry up that venous bleeding and make it so that the rest of the dissection is nice and dry. But here's the optic nerve, and you'll notice that I'm pulling the aneurysm away from the nerve and that's the real key point. All the dissection moves the aneurysm off of the nerve rather than deflecting the nerve. And the other important point is that I like to leave that arachnoid layer on top of the nerve and not violate that during the Sylvian fissure dissection or any of any portions of the dissection, and that helps to preserve those perforating branches. Now getting to the clipping, you can see this is gonna be a tandem clip type construct with the fenestrated clip that has good closing force at the disproportion. And then my first thought is just one straight clip to close the fenestration, but that's not enough. This is a thick aneurysm with a lot of force, and so I've replaced that with a second fenestrated, and now the closing clip, the third clip closes the fenestration after those first two. And in this case, I even need a fourth clip, another fenestrated to close the, the neck. This is a little tailoring clip that goes within the fenestration, and that eliminates that little dog ear remnant that's part of that tandem clip configuration. So this I see green showing that we've got good carotid flow and this now is just a push to communicating artery aneurysm and a small anterior coronal aneurysm on the carotid just downstream. This is one of the advantages of dealing with this particular lesion surgically because you can deal with all of these lesions at one time. So broad-base, this would have been a tough coiling procedure, but very easy at the end of our dissection for the giant aneurysm to simply finish up with these mini clips. So that's a nice demonstration of how a broad neck with thick tissues can be dealt with with multiple clips in a tandem construct, and here we have a nice angiogram post-operatively showing how everything's nicely preserved. Now, this next case is just to show you the limits of what we can do. And, you know, I think we can really go far forward. Here this aneurysm is really sitting almost pointing into the cellar here, and that shows you the extent that you can take this dissection forward. And this it's a small aneurysm, it's a simple aneurysm anatomy, but it shows the ring dissection very nicely, which in this case, you really have to go circumferentia in order to fully expose this aneurysm and mobilize the carotid. So we're doing our craniectomy, you can see how it comes out. Here's that fiber and glue trick. It injects the cavernous sinus, and it makes the rest of this dissection essentially nice and dry, all that venous bleeding or ooze that we used to fight with, goes away with that maneuver. So here we're just drilling down the optic strut, your optic nerve is right here, and by extensively drilling the strut and following that over, you will get yourself around the distal dural ring which we see here. So here's the optic nerve, we're just cutting snip by snip across the dural ring, and we're chasing that all the way into the carotid cave. Now we're on the underside, we're now going under the carotid to finish the dissection laterally. And now you can see the carotid here, this is that choroidal segment up here and here it is between the ring here and the proximal ring there, this is choroidal segment. And now we're in that carotid cave portion where you have the carotid canal and you're up against the bone of the skull base here, and you're pulling the carotid out towards you. So this is what it takes to really complete that ring dissection 360 degrees, which is what we're seeing right here. Now, the aneurysm comes into view. Here it is, it's just proximal to that distal drill ring, and this is an upper curve clips. So the tips of the blades are kind of reaching up into the carotid cave under the carotid. You're almost having to lift the carotid up out of the aneurysm up out of the cavernous sinus, and that completes the clipping there. So one clip is all it takes there. We're just inspecting the blades, you can see there's a little push to communicating aneurysm here, but it just shows you the distance between the ring and the PCom, how much further forward you need to go if you're gonna get an aneurysm that's around that corneal segment or right at the distal drill ring. This is the green just showing that we've got patency and a fairly simple clipping configuration, unlike the last one. But the key there is just making a complete circumferential dural ring dissection, and getting that clip in just the right spot. Here's showing where the clip blades go very far proximal right as it comes through. So this is a very interesting case. I'm going to demonstrate the lateral super cerebellar approach. You can see this as a distal SCA aneurysm and the reason is there's an AVM on the top surface of the cerebellum. And the patient here is in the sitting position, and the beauty of the sitting position is that you see how the cerebellum sags with gravity. So as the cerebellum sags with gravity, where right underneath the tentorium, it brings us to these feeders on the superior cerebellar artery that go to the AVM, and gives us a very straight and direct shot to the AVM. So this was a small grade one AVM, not a difficult one to resect, but this was the reason for that distal SCA aneurysm. The vein now is nice and blue, just need to get around this posterior inferior margin of the AVM, and we can take that out. So the advantage of this approach is that it prepares you for treating the aneurysm at the same time. Since we're there and this is the source of the aneurysm, we can get rid of that first and you can see how with a little bit of cerebellar gravity retraction no fixed retraction is gonna open things up very nicely for us. So here, I'm just coming across the vein to finish off this part of the case. And now that's out. So now we're gonna transition in your view here is over the cerebellum into the genital and ambient cisterns, and that thick white layer is just the substernal membrane as you go through. So we open up those layers of the cisterns and you can see very nicely superior cerebellar as it winds around the midbrain, you can see those trabeculations in the ambient cistern, and it's important to really dissect this as widely as possible so that everything opens up, we're coming on the fourth nerve here, as it comes around and in that arachnoid layer. And now this is aneurysm. So those preoperative images pass by quickly, but this aneurysm was embedded in the midbrain, and that's what we're seeing exactly here, it's pointing medially into the substance of the midbrain, the efferent artery is here, the efferent arterioles over here. So I've put my temporary clip proximately, and now this clip is going to parallel the trochlear nerve here across the neck. I can't see the aneurysm fundus or dome very well, but that's not necessary, I just need to get it across the neck. Temporary clip comes off and now it's inspection time. We need to make sure that everything looks good. And because the aneurysm projects away from us, very difficult to see all of the anatomy that we'd like to see and what this next little sequence will show is that even though the aneurysm looks to be quiet and we do our IC green and it also looks to be quiet, there's good flow in the parent vessel here, no filling of the aneurysm sack. But I'm not convinced of that, so I puncture the aneurysm and you'll see that it's bleeding still. And what that tells me is the part that I can't see is right behind the inflow artery on the proximal portion of the neck, and so all I need to do is just advance that clip about a millimeter or so. That gets me a little bit further across the neck, and now that bleeding has stopped. So very important not to completely trust your IC green. It's very valuable. I'm a complete believer in that, but it's also good to validate that even though it's dark, it's still not filling. And you'll see here the trochlear nerve, I was a little concerned about the clip laying on the nerves. So this was just a pledget going in under the clip and over the nerve just to give some padding. And that's a nice way to make sure that her fourth nerve function is okay. But this is a very versatile approach, it shows you the treatment of both the AVM, and the aneurysm, and the benefits of gravity retraction. A little bit more awkward for me, operating on a stool with my hands in the air, but still you're using the natural benefits of gravity and the anatomical planes. So this is another challenging case, a tragic story of a young 24 year old kid who had an endocarditis that was from a mitral valve. You can see that stroke that became hemorrhagic, and he developed this mycotic aneurysm and his M1 segment which we see here was open, it fed just a single branch here on the frontal side. The temporal division was completely occluded and the only thing filling his hemisphere were these anterior temporal arteries here they came off approximately on the M1. This branch that I just occluded was already dead, this was the only live branch on the frontal side. So what I'm gonna be doing here is I'm transecting that branch which we see here and I'm going to re implant it on the inter temporal artery. So his circulation to that hemisphere was so compromised that each one of these branches was important, everything else coming off this aneurysm which you see here was already occluded from the infection, but this one is salvageable here. This rim here is what I use for my donor. So I make a linear arteriectomy. You'll see that the frontal branch has enough length of redundancy to mobilize it over. And so this is an end to side anastomosis. Again, this being the frontal branch, this being the enter temporal artery, this being re implanted onto that and to side. And you'll notice with the suturing technique here, it's an insight to technique. So I'm sewing the two inner most layers of tissue. The two outermost layers are kept to the side, and I'm just sewing that inner layer with a running continuous stitch. Now the needle passes to the outside so that I can tighten my sutures and tie, but then having done that inner layer of suturing, we can then go back and sow the outer layers, the oversewing portion of the anastomosis is what we do now, and so the needle just goes in the other direction, again, a running continuous suture, and you see how this frontal branch has now salvaged. The frontal branch is preserved, the temporal artery is gonna be released here in a minute, so we haven't lost anything to that supply, and we've got a nice revascularization of his circulation. Unfortunately, all the others were already gone and he's already had that hemorrhagic conversion of his stroke that these other territories were viable. So this completes the anastomosis and we'll take the clips off, make sure everything looks good. I always like to see a little bit of back bleeding, it just shows me that everything's patent, if you don't see that it's usually a bad sign. And then the IC green here confirms that we've got to patent an astomosis. And here you can see in better view this connection and to the side. And post-operatively, we did an angiogram, you can see patency of that re implantation, seen best rate here, and good reconstruction of his MCA flow. Now, this is a case, very similar to what Robert showed you. Again, extolling the virtues of this contralateral approach, very similar in its anatomy. But again, just to emphasize that crossing trajectory across the midline and going through the faux really gives you the very best trajectory to get along that most difficult plane, that medial portion, sorry, that lateral portion. And you know, when you're dealing with an AVM in the dominant hemisphere, it's very preferable because you don't have to go through brain to get there. So this is just the interhemispheric dissection down to the Corpus callosum. Again, no fixture tractors needed for this. You can see the faux here, you can see the arteries nicely, but in order to see the veins, you've gotta cut through the faux and resect that significant portion of the faux. Now we can go at the AVM, here's the large ACA feeder, so we can take care of first. You can see it's a very nice trajectory down, but even better as we start to go across. Now, you can see the veins in view here going up and over the field, these are more feeding arteries from the close of a marginal portion of the circulation. And here's that view that you get going over the top. So as we go further and further laterally, the AVM falls down into your field, you get a nice view of that separation plane between the deep white matter of the left frontal lobe and the AVM margin. And you can see we're starting to darken the vein here, we're starting to get some mobilization as we free up that anterior pole. And this really gets us over the top laterally. And so this is that view, there's just a retraction on the faux here, but everything else falls away with gravity, and here is the AVM as it comes out. Here's the overview at the end showing the exposure and also that defect now on the faux which of course doesn't matter. Here's our post-operative angiogram confirming a complete resection. So it's counterintuitive to want to go on the opposite side and not have the veins and all the anatomy directly under you but I think it helps with the view. Now this one is a smaller AVM in the cottage head. And I'll just show this to sort of extend the concept. This is the feeders that you get with these small lenticular striates from the proximal A1 and the proximal M1. And the position is the same, the head is turned so that the midline is horizontal. You've got the forks up here the right hemisphere is down. We're getting ourselves directly into the left lateral ventricle. So this is what makes it the contralateral approach. So as we get into the lateral ventricle, we start looking for our landmarks. Now this was an eight year old boy, he was told locally that this was an inoperable AVM, and it was referred for gamma knife radiosurgery, but this was a ruptured AVM in a kid. And so this was in my view, it was one that was more favorable for surgery. And this is a again, that crossing trajectory that gets you along that lateral margin of the AVM. And these are the keys to the case, these little arteries that go through the white matter and get to that lateral border of the AVM from underneath, those are the real danger. If one of those gets away from you and starts to bleed into the white matter, then you have to chase it down in the deepest portion and in that the most eloquent portion, and that's where you can get your morbidity. So those are very carefully dealt with, with these AVM micro clips. And you can see that now the Knight is as we work our way around is freed up on the anterior aspect, the inferior aspect, we're pulling it down in towards the ventricle and a just needed to work now on the posterior margin which is here, there's a few more features that came in from the back, which we'll find and take care of. And finally, you know, you finally get to that carotid vein that typically drains these AVMs. And we like to see that nice and blue, which at this point it really is. So there's the resection cavity, those little micro clips down there. Here's our vein, she'd come into view in just a second. There's the vein right there, so that's our nevus pedicle there at the end. Everything else is free, so we just have to detach it from the vein here and it's taken care of. So that's a very nice view for a tough lateral AVM. You're coming from the right, you're going all the way to the left and you're at the bottom of the cottage head. So that is the kind of exposure that you get with this head position in your gravity retraction. post-operative angiogram showed a cure, patient did well, and we had no trouble with this one. Michelle case not unlike what Robert showed you, but a little bit deeper. You can see the AVM here in the insular region. This is one of those AVMs that didn't have a very dramatic angiographic appearance, I think mainly because this was a very high flow shunt that thrombosed rapidly and the patient presented with symptoms from edema related to the swelling. And you'll see as we get closer down to the AVM, how this verus was thrombosed, but again, this takes a very wide Sylvian fissure split, it's what I call a posterior Sylvian dissection, not just your typical anterior one that we use for the MCA aneurysms, but if you're going to open up that much of the Sylvian fissure, it really is helpful in my view to open up both anterior and posterior Sylvian fissure. So now we're in the posterior portion, you can see that kind of grayish greenish vertex here underneath the vessels. That is that thrombotic seal part. And again, another nice example of vessels on facades that go right by the AVM and don't contribute as we see here, you've gotta be very careful about how you identify and protect those, you've gotta follow them from the back forward, make sure that you only vertex the vessels that go to the AVM, you got to respect those planes of dissection between the insular cortex here, and the plane of the AVM there. This is dominant hemisphere, a young guy with no speech deficits. So it's very important to respect those planes of dissection which we see here. And again, it's just working your way around that plane and the knight is. You can see how dark this is already, makes it a little bit challenging as you resect these AVMs because without the presence of a red vein, it doesn't give you as much guidance in terms of the progress of your dissection, it's nice to see it go from red to blue, but when it's already from thrombost you don't get that color change. Here we are coming across some of the final feeders on the temporal side of the fissure. Again, a nice skeletonized passage artery here. These are some of the final connections and you can see how the AVM is mobilizing away. So again, this is pretty deep. We're all the way through the operculum past the long insular vessels and into the deep portions of the insula. And it's a sizeable knight. So tough getting around those last little portions. I do have a retractor in and I think, you know, we shouldn't be overly dogmatic about the exposure that we need, in this case it helped me see around that last little bit of the corner. And now I think the knight is free. So it comes out nice and clean, you can see how much of that varix had thrombosis that really didn't appear at all in the angiogram preoperatively. And you also see the preservation of these passage arteries. So this was dominant hemisphere, the patient had no speech deficits afterwards and really had a smooth course. And again, it's because those tissue planes turned out to be very clean as we were going around the planes down around the insulin. Post-operative angiogram looked good. This one, I don't have the preoperative films. This was the late breaking one, I think we did this last week, but this is a giant MCA aneurysm and thrombotic. The luminal component was about three centimeters or two and a half centimeters and the rest was thrombus. This is on the right side, this is the carotid the M1, this is all aneurysm here. And so my first thought, and you'll see it didn't turn out to be right. But my first thought was that we'd do a thrombectomy and attempt a clip reconstruction. So this is the coming in, and as you get inside the aneurysm and gut this thing thoroughly, you can see that the aneurysm softens. Now, I had no distal control, I had proximal control which I showed you. But once this soften, then I could gain my distal control here, I could find those outflow vessels as they left the aneurysm, and now with a complete control I was able to completely finish it. And those are the inflow and outflow vessels seen from the inside, you could see how they just came in and left separated by about a centimeter. And so the thought here is to resect the aneurysm and see if I could just fold things over or placate the base of the aneurysm and get that closed, knowing that this wouldn't be a perfect reconstruction, but just creating a little sack so that inflow would connect with outflow. And so this is my attempt at that. We've got for our first fenestrating clip applied on top, this is the second one to pull things together, and obviously not perfect, but just to gather things up and finally, I mean, apply that last clip underneath to pull it all together. And you'll see on this IC green run, that actually there was flow. You know, here's the outflow vessels coming out of the aneurysm. And as we look at this, we've got flow, but here's the outflow here. But as I watched this thing for a couple of minutes, it became clear in Doppler confirmed this, that this did not last. It went on to thrombosis very quickly and so we have to resort to something else. And so now we're putting clips a little bit more close to the neck and I'm going to excise the aneurysm completely. There was that outflow. Here's the inflow. It would've been nice to just be able to pull these together, and there's a real strong urge to do that because it's quicker, it's easier and more natural. But the problem is there's a lot of pathologic tissue here, pathologic tissue there, and if you put them together under tension, you're bringing bad tissues together under tension, and it's not likely to work. And so the answer to that is to bring in a short segment, inner position graph. This is a radial artery, this is our outflow effernt M1. And this is again that kind of insight to techniques sewing from the inside of the arteries with running continuous suture. And once those are in place, you can now sow on the extra luminal side. So this is an end-to-end anastomosis, and that brings together the radial artery graft distally with the M1 segment distally. And now that's in place, we can trim the radial artery graph, we focus our attention on the M1 proximally. And again, that same suturing technique running continuous sewing on the inside of the vessels here. And now we can complete the second suture line on the extra luminal side and tie it up. And now we've got two anastomosis, we've got an inner position graph and we've reconstructed what turned out to be an unclipped reconstructible neck. So here's the graft winding its way over. Here's one anastomosis, here's the other. Here's a green which shows good filling.

- [Dr. Michael] Yeah, it's a great question. Aaron was asking, how long did that take? And you know, here's the thing, you're worried about the ischemia time, but the thing was you could either say, well, "Jesus, this is too long, why am I even doing this?" But during the case, the patients MVPs and SCPS did not change. And what that told me was that if I didn't do something that there'd be ongoing ischemia and the patient could develop a deficit, whereas if I just kind of bit the bullet and got this done, we could rescue that ischemic tissue and get them out of danger. So that was the reason to keep going they didn't change. Had they changed, then I would've dampened my enthusiasm to keep going, but I think you've got to use your neuromonitoring as your signal to press on. And in this case it was a good bet because she woke up, she had no deficit and I don't have the angiogram to show you--

- [Dr. Michael] Yeah, she has some collateral. But if you left it just to the collateral, I think it would have been inadequate. Finally, this case is another example of an interesting bypass, you can go ahead and roll that, you know, you've got a PICA aneurysm with inflow and outflow separated here by about a centimeter. And you've got also this calcified wall seen here and here. And in this case, you know, my options were either a re implantation of PICA onto a vertebral artery. Or I was thinking PICA-PICA side to side anastomosis, like we often do for these, but the anatomy here is a fortuitous, which is one of the reasons I wanted to show you this. Sometimes you have to just have an open mind about what you do based upon what you see at the time. And there's the PICA coming off of this aneurysm here. And look how much redundant loop there is. There's all this loop and there were no perforators going to medulla here. And so what I've done is I brought the end of the artery over to the contralateral PICA. So this is like a PICA, PICA, but rather than it be a side to side connection, bringing the caudal loops of PICA together. Because of that anatomy, I was able to swing the origin of PICA all the way over to the caudal loop. So the rest is just a fairly routine. This is an end to side anastomosis. So we've got a fish mouth here on the PICA of origin. We've got a contralateral PICA that we are arterialized here linearly. And the technique is like what you've seen on some of the other videos here, we put in the two anchoring sutures. First, the heel stitch here. I like to do that first because it's always a little bit harder to see that once you've anchored the toe. Here's the toe stitch, and this one doesn't really require that insight to a technique. Sometimes if the artery has a little redundancy and you can move it more freely, you can flop it from one side of the other and just do all of your suturing extraluminal, which was the case here. And I think that makes things easier. The nice thing about the PICA of territory is there really are a lot of options. You know, you have the contralateral PICA to work with, you've got the vertebral artery to work with, if you need to re implant inner position graphs work nicely because if you need a donor, you can go down to the V3 segment and you know, it really creates multiple different possibilities. So in this case, this re implantation was nice, I haven't done this before so just a little variation of that. And this revascularizes the PICA on the patient's right side. And interestingly, the patient had a couple of perforators on this aneurysm that I was concerned about. My plan was to trap after this PICA was re implanted. But instead what I did was distally occlude and left the proximal flow in to just feed those perforators that came from the aneurysm and that worked fine. So here's that occluding clip on the PICA, we've got our anastomosis here for our re implantation. ICG confirms everything's Peytoned. And there's are an estimate on the post-op angiogram. You can see from right all the way to the left, and here it is once again. So the flow of the proximal inflow to the aneurysm I left. So this was just a distal occlusion to preserve perforators. Thank you.

- [Dr. Paul] I Think I have a couple of cases actually, a nice segue into this. And I'd actually like to get my co-panelists advice on this particular case, which I don't think I handled as well as some of those we've seen. If you go ahead and play this. This is a 79 year old woman I believe who presented with subarachnoids hemorrhage. I'd like to thank my fellow Dr. Chabot for all his help with both the cases, as well as the video on this. She presented with a grade two subarachnoid hemorrhage. You'll see on the CT a typical fair amount of posterior fossa blood in the perimedullary cistern. And she has the sinus is in which the challenge of is that the vert curves right across midline, and is in line with the aneurysm which really makes it very difficult or a possible for it to get distal control. Now this video is actually I believe flipped just backwards, it's upside down, so this is sort of a opposite view, the cerebellum's over here and this is inferior, just dissecting out the aneurysm around the 11th nerve between the lower cranial nerves and 11th nerve, and then getting proximal control on the extradural vertebral artery before it enters into artery. Again, this is cerebellum superiorly, so the view sort of flipped upside down. And I'm dissecting across the neck of the aneurysm, putting this side winding clip in line. I thought to at least in line with the vertebral artery and my distal point of the clip goes right through, I think part of the neck of the aneurysm or at least peeling it down, get some bleeding from the aneurysm, nothing that's terribly out of control, but again, I don't have good distal control here and I couldn't figure out a good way that I could even see the distal vessel to get good distal control on this. So I placed a clip across the neck of it, I thought, you know, it looked pretty good, I thought I can see the PICA filling here nicely, but because of the angle of it, my clip actually completely occluded the vertebral artery, so I did have PICA fill I had preserved that, but I'd occluded the distal vert. So obviously I have to come off here and find a different angle to come across the artery. Again, I'm struggling based, 'cause I can't see the distal vessel a well at all. So I replaced this kind of in the opposite direction, again, I have a clip on the proximal vertebral artery to get pretty good control there. I come off the vert after replacing these, I still have some doppler blood flow I thought in the PICA there. But when I look on the angio, I have left a little residual and I don't have any flow in the PICA at this point, even though I thought I could see how it had been preserved. So I wanted to reposition these one more time and this is kind of when things started to get a little hairy. So as I took these clips off, this was when the aneurism really started to let go quite a bit. Again, I still have proximal control, but I don't have a good way to get distal control, so I put a cotton wool on the bleeding point and place a clip across there, but when I go to look at the cotton wool of course, I've managed to clip that in place. So I'm kind of making pretty much every mistake I can make here. And so I take the peel the cotton wool out, maybe I probably should have just left it there and trimmed it in place. But at this point from my distal control, I give some scene and that worked quite nicely. I'm able to get the clips off and get a much better look at the aneurysm in this case. So I had a nice long run and I can see the veins very nice, I can see the PICA coming off, and I'm able to get a clip across it at a better angle in line with the distal vert, which again I still can't see very well. I'm doppler in proximal, I have good proximal flow, I have a doppleble flow here in the PICA. At least the proximal PICA. You can see the aneurysms occluded, but the distal PICA, I was not able to reestablish flow even with approximate was and so she developed this infarct in the cerebellar portion of the PICA. She did not have a maxillary infarct, she did have a long-standing vocal paralysis, I think just from lower nerve manipulation, some advice from my panelists, I guess on perhaps different ways to manage that or a different option for how to treat that with a little better control or a little better clip options.

- [Dr. Robert] Yeah, it's always easy in retrospect. I would not have been satisfied with your exposure in putting on that clip. I think that's one of the mistakes we make when we don't see the surrounding anatomy. The second is that once that clip was on and you had the bleeding stopped and you had an intraoperative angiogram that showed that the PICA of his filling, why not check the other retrieval artery to see if you didn't have adequate filling of the posterior fossa and stop because I mean, you had at least one good vertebral artery, we don't know about the, the PCom but sometimes we get so focused on wanting to achieve a goal and forgetting that we really want to preserve function.

- [Dr. Paul] This was a very, very dominant and so my assumption in my head which as you say, probably not true is that this is, I can still look and see if I have filling. Yeah, it's a very good point.

- [Dr. Michael] Yeah, it looked like you were taking or repositioning the clip to salvage the PICA which was occluded. Yeah, so, I mean, the other thought would be if the other vert was good, just stop, leave the torn aneurysm and just do a PICA bypass and take care of your PICA only.

- [Dr. Aaron] Paul I have torn PICA aneurysm necks more than twice in my life. Actually I had one of the videos here. It's pretty dramatic, I took it off, so retrospectively anything can be perfect but challenging case, I think you do the best you can and that's what's important.

- [Dr. Paul] Thank you. I think those are all, I think, very good ideas and certainly I think what I would apply next time. No worries. This is a sort of more complication avoidance, this is a 36 year old physician actually, who has this as a known hypothalamic pilocytic astrocytomata and has had progressive vision loss despite having completely stable imaging. She received a radiosurgery 10 years prior and this has not changed at all. She's had developed this necrotic center, she's had no growth of this but has had progression of her vision loss. So because of that, I just wanted to... Can we just go back for one moment? I wanted to offer her just the decompression. And as you look here, my natural instinct is to perhaps this is a good endonasal case, but fortunately we did a hi-def fiber tracking actually of our optic... If you can go ahead, of her optic nerves and what you can see is that they're all at the inferior aspect of the tumor. And this was not something I could really tell looking at the standard MRI, but you can see how obviously why her right eye vision is gonna be so much worse, you can see how much more impacted is. So instead of I chose a transcranial approach, a super orbital eyebrow incision here just in the lateral aspect of the eyebrow. And here you see the incision that we used. And so this was, I think using more and more high-definition fiber tracking can help us tell where tracts and nerves are to try to avoid injury. Here we're identifying opening the optical crowded cistern. I see the carotid very nice, I don't see the optic well in this case because essentially on this side is completely full of tumor. I'm just splitting the proximal fissure. So once I have approximal fissure split, I can see my A1, which should tell me where the genu of the chiasm is. But again, it's completely infiltrated with tumor here. I can't tell where the nerve is. And so to me, it sort of makes sense to go back to the bony anatomy where I know everything has to run into its appropriate frame and I'm just dissecting out the A1 to try to get a better idea where that genu might be. So dissecting along the A1, I'm defining this anatomy, but I still can't see where the optic canal is. So I go back to perform a craniectomy. I know there's no tumor going into the canal, so by resecting the clinoid, I now have a good idea where my optic canal is, I can tell where my A1 is, and so I know I have a good entry point into the hypothalamus between the two essentially, so I can go just medial to the nerve and the genu. Again, this is a virtually a blind eye although there is some vision left here. And do a complete decompression here in the hypothalamus. I can decompress the optic canal opening the falciform ligament. You can see here we start to see some hint of a normal nerve coming in here. Here's again, the carotid, here's the nerve coming in, somewhat normal, and I just left all of this because this is infiltrated caesium, this is infiltrated genu between the nerve as you can see in the canal, which is normal right here, and then immediately gets blown out by tumor, and then I resected everything I thought I could safely at least between there in the A1. Again, this was a very stable tumor. I didn't want to get too aggressive. I got about a 50% reduction in the volume of the tumor with no complication for her fortunately, and she was able to have actually pretty significant improvement even in two weeks in her visual field. So I think more and more of these techniques like fiber tracking can really help quite a bit. And then one final one is I think a 2D, if we can switch over to the 2D please. So this is a 60 year old woman who presented with double vision, multiple episodes of double vision. We followed her for a long period of time and she was found to have this tumor here at the base of the skull. You can see here it's pretty intimately associated with the carotid. You can understand it's sort of in the crook of the vertical segment and the horizontal segment of the peaches carotid. This was thought maybe there'd be a chondrosarcoma or a potentially schwannoma. She watched it for a very long time, eventually this continued to grow and so she wanted at least a biopsy or debulking of this. Here we can see its intimate relationship with the carotid artery. So of course we did a endoscopic approach for this and you can see here's the cellar. This is the para clival vertical pietas carotid artery, here's the tergal palatine space, you can see where from where is entering to give us good access to Meckel's cave. And because the artery is really pushed medially and posteriorly, I have a pretty good access directly onto the tumor. So I'm at least able to open Meckel's cave, do a nice dissection of Meckel's cave. Again, here's sellar, so we're in Meckel's cave down here. I can identify the carotid artery and start to peel the tumor out. This is just a standard cartouche dissector like we would use for a acoustic neuroma surgery and the tumor turns out to have a pretty nice plain with a carotid. I can doppler it after I dissect back behind the tumor. Again, I'm sort of staying between the carotid and the superior orbital fissure opening a bit of the capsule of the tumor, and with a combination of blunt and sharp dissection, you can see appeals pretty nicely off the carotid. When I get down where the carotid itself is invested with a much thicker fascia, I'm not able to really get quite as nice of resection or playing with a carotid. So we just do a piecemeal resection at this point. So now I want it to wait and see what the pathology was. I've decompressed her six nerve. If this was a schwannoma, she didn't necessarily want a complete resection given the higher risk we thought to carotid extending and fairly. So I stop here and actually, you know, one of my trainees was trying to stimulate some of the six nerve and ended up with some very brisk bleeding here. So first thing we do when in common is control it just by placing a cotton wool over it, try to avoid the instinct to try to inject surge of foam or something, but just putting the cotton wool over and trying to get some idea where the bleeding's coming from. Again, I know the pair carotid is here and this degree of bleeding makes me pretty confident this is an arterial injury, and this is right where the artery enters into the cellar and it's a very difficult areas you can see to even visualize. I actually do have proximal control here by putting an aneurysm clip with a single shaft applier on the vertical peatre, but there's clearly a good crossbill and risk back flow. So I'm getting a pretty brisk backflow and I can't get a good visualization of this. One of the other good options here is just to pack this off with muscle, but I wanted to try to get a visualization of it, I didn't feel that the proximal control was helping me much, I was sort of fighting this a aneurysm clips. So I decided I would remove this given the backfill and maybe just try to buy myself some time by just clipping directly across the artery right where it was bleeding. So I couldn't get good distal control without a little better exposure. So I wanted to just stop the bleeding for the moment maybe get some better distal exposure, but as I started to try to work here, I all of a sudden was able to see a little better the opening and the artery. So rather than completely occlude the artery, I decided maybe I could just pinch it off and get a little better closure here, so I can see the opening and the artery. I just took this 90 degree angle clip and fortunately, this is a hole in the artery directly facing us so I'm able to just pinch it off. And that kind of got things under control very quickly. At this point, we had gotten pathology back this came back as a schwannoma, likely one of the little parasympathetic branches of the schwannoma, the branches that run or rather sympathetic branches that run with the carotid all the way from the cervical carotid up to cave and the cavernous sinus. So after this, obviously one of the issues you have as well is how do you deal with this aneurysm clip? We've had clips that have eroded a bit. I wanted to get a little more room obviously here, we're away from the horizontal peaches carotid which dives away. So we pack fat around this essentially, and that allows us pulsing a clip that we have in the nose to not penetrate through our nasal septal flap. And then we just placed the nasal septal flap overlying that. Again, this is extra dural surgery, so I'm not worried about spinal fluid leak, I just want to protect the artery and I want to protect the clip. Here's the post-operative angiogram. We're very fortunate. I did actually give her a little bit of heparin interoperatively, I've had a couple of cases where I got thrombus and even emboli from this, but I think we're able to... You can see a little bit of stenosis of the vessel at this level but able to preserve it pretty well for her and had a reasonable resection at least of the cavernous sinus portion of the tumor. So thank you very much.

- [Dr. Paul] I do wanna take a moment to thank both as well as Aaron who's put in as usual tremendous amount of work to bring all this together. So thank you.

- [Dr. Aaron] You're welcome.

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