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Grand Rounds-My Pearls of Technique: A Review of Challenging Cases

Michael Lawton

July 15, 2013

Transcript

- Edo, can I have my video? Okay, so I'll just do what Robert did and take you through these different cases. This one here is a patient presents with this giant MCA, aneurysm and it's a nice demonstration of some bypass techniques. So, what we're looking at here is the splitting of the Sylvian fissure, and you can see how this aneurysm really fills the entire Sylvian fissure. This is a thrombotic aneurysm. You can see the M1 segment filling in. You've got an adjacent anterior temporal artery, which is something to remember, because if you consider your bypass options, you wanna think of all possibilities. And the anterior temporal artery is a very nice, a donor vessel, if you need it. Here what I decided to do is to clip the aneurysm and the first step just to get some working room is to just do a thrombectomy, get some decompression of that mass of the aneurysm and get down to that lumen. And that's just the Coosa, like we're all familiar with for tumors. And you can see that as that massive of the aneurysm dome softens, it gives us some flexibility to kinda hold a wall in and separate off the vessels. Now, that's the cut end of the M1 proximally and that's the cut end of the M2, of the M1 distally. And there was enough redundancy in those two ends to bring them together. So I really liked this intercranial arterial reconstruction. It's an end-to-end anastomosis. And when you have that redundancy that allows the two ends to come together, it's a very nice way to perform your bypass. It doesn't require any extracranial graph, It doesn't require a surgical incision, and it's a really nice match of pairing between calibers of the inflow and outflow. So, I'm very curious to look at Robert's technique, 'cause he's always taught me to do these with running continuous and I noticed some interrupted sutures, but what you'll see here is a little different. I do a running continuous suture, two knots, one on either end and one at zero degrees and 180 degrees. And then just by running a continuous suture from one knot to the other, you place these nice loose, loops of suture and that you keep everything loose so that the tissues are freely mobile. Basically, as those loops are placed, you leave the tightening to the end. We're not gonna worry about bringing those ends. And so all the bites are in place and that's when we'll tighten them up. Note the spacing, you want these to be really carefully placed. I like these, you know, at about that distance, it's maybe lots of fraction of a millimeter that you really want them nice and tight so that as you go through and tighten them up, you're really pulling the wall together, loop by loop of that suture. And at the end, you've got a nice tight snug approximation of that first wall and that allows you to tie to the ends of that previous knot. Now, what you'll notice to get to the back wall, you just rotate those temporary clips the other way that brings the back surface of the artery upwards in the field. And it's the same thing all over again, just doing a running continuous suture from one knot to the other knot. And again, it's about maybe 10 bites of suture. It's a lot of bites and so if you had to tie each individual knot, what you would find is you'd be doing a lot of time rather than a lot of sewing and you'd be eating up the clock in terms of your scheming a time. So there's our end to end connection. You can see plenty of give on the tissues. There's no tension in bringing those ends together. And our IC green angiography shows that there's a nice filling of that distal trifurcation. So they have it, it's a decompression with a thrombectomy doing an excision of the aneurysm and bringing the ends of the vessel together.

- [Erin] Michael, I asked you though to do one case at a time. I think you wanted to discuss a question with Dr. Spitzner regarding this sewing up technique?

- Yeah, Erin, where are you? I can't see where you are.

- [Erin] I'm right here.

- Oh, there you are, okay, yeah. Robert, do you have a comment?

- [Erin] There's one thing you left but I'll give one.

- [Robert] No, I think that's beautiful. I in fact do the bypasses almost always with a running suture because so many are deep, It's much easier to do that, always wait until the end to tighten those knots just like you're doing here. When I'm really worried, I'll do the interrupted, just so that you eliminate that tiny little snugness that you get from the ruptured from the continuous suture. And if the end of the vessels have the ability to grow that the suture, which is continuous, doesn't prevent that. but the vast majority of time it's continuous, okay?

- The only other thing I would say about the end-to-end anastomosis is that anytime you're excising a segment of vessel where the aneurysm used to be, it naturally creates tension and bringing those sutures together. So there's always a reluctance to cut too much back to normal tissue. And if you don't cut completely back to normal tissue, you'll have a little end of abnormal tissue that can destroy the bypass. So it's a very fine line and I've been burned now. Okay, can we go to the next one then? Okay, this is a another giant thrombotic this time on the internal carotid artery. And this is just the view down the Sylvian fissure. So left-sided approach, you can see the carotid, you can see the aneurysm, the uplifting of the optic nerve. And so this is one that has a neck that's really hidden by the anterior clinoids. So in order to get a exposure on this, I needed to do a clinoidectomy. I just make these flaps of dura over the clinoid and drill it out. There are many ways to skin a cut, you can do an external clinoidectomy, you can do an interdural clinoidectomy. My preference has always been to do intradurally so that I can see everything in my field of view. I can see the aneurysm. I can see the clinoid, I can see the optic nerve. The downside is you get some bone dust in there. You get a little bit of blood from clinoidectomy, but I think it's well worth having all that stuff at hand. So you can see the carotid kind of pushing into the optic nerve. And what happened with this case was that as I went to go clip the aneurysm, it ruptured on me and tore. And so what I've done here is I've trapped it. I've got a clip proximally, and I've got clips distally. So I've gone in again and decompress the aneurysm with the thrombectomy. So the aneurysm is between the clips and this is just kind of mobilizing things to expose the anatomy. And this is going more immediately just to show you the extent of this giant aneurysm. And I decided at this point that I needed to do a bypass. I wasn't expecting to have to do one because I figured that this neck was salvageable, what you're seeing there is the outflow from the aneurysm and the temporary clip is on the, the distal end of the stump of the internal carotid. And so what I've done here is that harvested a vein and I'm sewing into the end of the super clinoid segment end to end. And the reason I'm doing this is that I've already sacrificed the distal carotid because of the way that the neck tore. And I wanna preserve the choroidal which is on the other side of that temporary clip. I also wanna preserve the crossville from A1 to M1. So that left hemisphere is getting its profusion if I resorted to an MCA bypass, I would have scheme your time that I wasn't comfortable with, because I had to go and get the vein. So in any event I've used the distal carotid artery, therefore to, so the end of the vein graft into.

- [Erin] Where is PCOM here?

- PCOM is involved at the aneurysm and not.

- [Robert] So that's gone?

- That's gone, that's gone. And that's why rather than doing an MCA recipient, I've chosen to do a distal internal as my recipient. So that's another end-to-end anastomosis into that distal stump of the internal choroidal. And choroidal by the way is being profused now, because it's on the other side of that temporary. So now we've got our distal end. Now this is just going down to the neck and this is the stump of the, I believe it was the internal. And again, just as all the other bypasses, I like the running a continuous, this is just an example of how, when things are a little tidy, you can run the suture working intraluminally. So you fold the ends of the artery out and do that running intraluminal suture line. And then with the other arm of that double on needle, you can run the other way. So that's an end-to-end anastomosis from internal to our graft. That's the cervical incision. Now we're running up here, good pulsatin down there. And there's the other end of the incision going into the distal end of the internal carotid. So if you can stop it there, that just shows you how, again, there's just enough of that distal internal carotid artery left after this thing ruptured on me to use that as a recipient and that allowed this cross communication from the AECOM to refuse the MCA territory during that expedia time. I mean, I think the natural instinct is to, you know, thank you. It's too difficult to work there, let's go out here, but that would have required interrupting things and increasing the ischemia time of that.

- [Erin] Any other thoughts from Dr. Spitzner, Dr. Painer?

- [Painer] No, I like, I doubt that the burst suppression that mild hypothermia, that you wouldn't have bypass in the middle cerebral artery, but it would have been the thinking of preserving flow at all times I think is very sound.

- Thank you.

- [Erin] I would agree, I think for an aneurysm that size you might consider preparing for an MCA bypass, it is a potential.

- Yeah, this is a great example of hubris and thinking that with clinoidectomy and good control proximally and distally that you can clip this thing and I think my guard was down and I wasn't really prepared for that. I think we had things straights, but we certainly didn't have them as ready as we should have that complication. Okay, yeah we can roll this one. So this, I believe is a sub arachnoids hemorrhage case that came into our service. On the right side, you can see the sub arachnoids hemorrhage there. You can see the blood in the Sylvian fissure, and you can see the aneurysm essentially filling the carotid cistern. So this is another one of those where I decided to take the clinoid down and I'm showing two clinoidectomy cases, not because I do it so much, it's just that when you're in trouble or you really need to get proximal control, sometimes just taking the clinoid out and getting that really good exposure, can make a huge difference in the case and with the clinoidectomy you see there, I have very good proximal control now, and I'm gonna use that. I just didn't have that before without the clinoidectomy. It's really a very benign thing to take that down. So I've got proximal occlusion, and I'm gonna use this clip. This is a permanent clip just to essentially trap that segment and get things going. I'm gonna open up into the aneurysm. I really can't see the neck very well, despite moving at one way in the other. And so I've just trapped it and I've opened it up to remove the thrombus. And that just allows you to, again, remove some mass effects, debulk this, and create some working space. So the aneurysm comes out and once that's out, you can then essentially work out more freely around. Now, I can readjust that clip application. Now you can see the neck very clearly. I've got one clip going from distal to proximal, I've got this second clip going from proximal to distal, and the tips meet right in the middle there. And so now we've got a nice clip to clip closure of that neck and having done the thrombectomy allows me to really see that very clearly. Here's our IC green intraoperatively showing that we've got good carotid preservation. We can flip that thing around one way and the other, and you can see good filling of the A1, good filling of the M1. And that's the view of the resected dome. So I guess the lesson on that one is that make sure you have adequate control. Don't be afraid to get inside the aneurysm to make things a little bit easier for you. And when you first put those clips on, when you're dealing with, if you could stop it, if you first put those clips on, you've got to really keep working until you see everything. Until you can see the blade from one end clear to the other, make sure that the carotid is preserved and that everything's nicely closed down.

- [Robert] I would agree, Mike, that was a beautiful case. I think one thing you did there that you didn't mention, but I think is very important is that when you're gonna open a thrombused aneurysm, try to open it as far away from the neck as you can, because when you got that thing, you don't know how high up on the neck you're gonna have to actually apply the clip. because if you have a very thick wall at the base, and you don't have enough aneurysm, you're gonna stenosis the parent vessels.

- Yeah, that's a great point. I like to make just a little kind of cruciate incision right at the dome. That way you can get in, you can get out and it's not too hard to close for an escape.

- [Erin] Michael I wanted to ask, how liberal are you in terms of using low diverters, in aneurysm of this type or both for ruptured or unruptured?

- Yeah, I would certainly not use it on a rupture case like this one, but I wouldn't really use it for pair clinoid aneurysms that are unruptured that have suitable anatomy for flow diversion. I think it's a really at its best in this periclinoid region. So I'm completely supportive of. Okay, I think we're gonna move a little back into the posted circulation and this is a right orbital zygomatic bifurcation. I think it's a fairly simple one. Just to sort of show you the basics. Yeah, so it's very small, nothing too threatening, but the size and the neck morphology just really, wasn't so favorable for endovascular approach. And this is a guy who had a positive family history and was very nervous about not treating this aneurysm. So this is just like what Robert showed, you can follow your anatomy so well, you can follow the PCOM. You can get into the space where the intra choroidal artery follows the incus back towards the choroidal cistern. And by opening up right along the intra choroidal, you really mobilize the temporal lobe. And this is going over the third nerve and following the P2, which I liked to take all the way around the corner to the tentorial incisure, because really that triangle, that you're opening is the carotid oculomotor triangle. And you can expand the triangle by kind of drawing the temporal lobe back. So now we're down to the basma trunk. You can see a temporary clip that go on here. That's the very small window that we're working through. And this turned out to have two sacs to it or two domes to it. And so this first clip looks like it's completely missing the aneurysm, but there's a little lobe in the back that clip takes care of first. And then once that posterior lobe is taken care of, then we can apply the slightly curved second clip for the more anteriorly projecting lobe of the aneurysm. And then the temporary clip can come off. When I see a thin wall like that, I like to use a temporary clips just to make sure that it doesn't tear the vessel. I don't often use temporary clips for small aneurysms like that one, but in this one, looks so thin and it was a little hard to see around the back. I just felt it was safe. And I think for the young surgeons who are beginning their experience with basilar aneurysms, I think it's very useful to use temporary clips more often than less often because it just gives you that extra bit of confidence ad if things don't go right, you're prepared and you don't have to fight that battle of getting the temporary clip on there. So questions on that one.

- [Erin] Doctor Spassler or Painter please.

- [Robert] I agree completely, I think the drawback of temporary clips there is that you have very small space and if it interferes with the application of the clip to the neck of the aneurysm, then that's a drawback. But if you can put it into that corner as you had here, if you think it helps, there's absolutely no reason not to use it.

- And I would just stress for the younger residents. And particularly after my lecture this morning, these are the kind of basilar aneurysms that you wanna start with. I think as I said today, we need to be ready for basilar aneurysms. We can't just turn these over completely. And when we get cases like this that have two lobes that would require a stent or can't receive a coil securely, then we need to be ready for these. And these are the kinds of more simple, small aneurysms that I think we can really do well with. They're no more difficult, more difficult than SCA or an MCA aneurysm. It's the same technique of just going a little deeper, seeing everything in your field of view and applying that sound technique.

- [Erin] Michael two things, number one, I'm left-handed and it's nice to see somebody operating with their correct hand. Number two, how often do you use the subtemporal approach for basilar aneurysm?

- Very infrequently, but I will say that I use the organizymatic, which gives me both. I can go from the front if I don't like what I see, I can swing to the side and I can do everything in between. So I like to do it that way because it just gives me options.

- [Erin] Thank you.

- Okay, down a little further to the superior cerebellar artery. This is an orbitozygomatic, as I said, I like these for that region just to get some room and here's this particular case. Sub arachnoid hemorrhage case, and we're on the left side, so everything's a little different from that last case. But you can see that as you open up that triangle, the thing to remember about these aneurysms is that like with this one, the dome is projecting straight towards you. So it's right there, right in here, projecting straight towards you. And so, you've got to work between the third nerve laterally trying to fight your way down to the proximal control, which is I think the real challenge is you've got to work yourself past the dome, like I have here, get to the basilar trunk and establish that before you get into trouble. And so, this is what I've done here. I've now got a view of the SCA there that's the cleavage of the distal neck. And on the medial side, it's not entirely clear. I mean, I've got a good view of the neck, but I don't have a complete view. So, this is a slightly curved clip and you'll see that, things are quite clear for the lateral blade, not as clear for the medial blade, but now that I have this clip on, I can see the SCA as well taken care of. And I can be a little more aggressive here on the aneurysm dome and I'm pulling it towards myself. And now I can finally see the origin of the P1, a little bit more clearly. And you'll see that that first clip is not quite fully across and there we have the second clip that does go fully across. So this is an example of stacking two clips, right into that little crook of the medial aspect of the neck. And using that first clip sort of as a pilot clip or a tentative clip that really sets the way for the other clip. You can see the SCA laterally. You can see the aneurysm here completely deflated. This is just a it's adhesions to the third nerve. And again, I think the biggest danger with an aneurysm like this, and even some of the basilar tip aneurysms is that they can project anteriorly and be a rupture threat very early in the case. IC green shows the SCA filling nicely. They're looking down at the basilar trunk and there's the P1 coming right by the tips of the aneurysm clip. So again, there's that carotid oculomotor triangle. And here's the result that we achieved with those two clips.

- [Erin] Now Michael, there's a few questions on what to ask you. Have you ever used bipolar electro coagulation, to do aneurysm or make the aneurysm shrink for better the application?

- Yeah, I'm real reluctant to do that because I'm cautery scares me a little bit. You don't have control of the thermal spread and the tissues. And if the perforators, particularly in this region, I think you can get into trouble with the perforator occlusion. So I would much rather put a clip on close most of the neck maybe not all of the neck and then work my way completely across with a deflated or softer aneurysm. I think that's a much safer way. I think as soon as you start cauterizing in this territory you're just not gonna see what you need to see.

- [Erin] Dr. Spitzner.

- [Robert] I agree completely. Where did you train that seem to have a such a similar point of view? I think one of the other drawbacks of really using the bipolar a lot on the aneurysm as you shrink the aneurysm down, and you get it to a very nice shape and you clip it, but where you coagulated the aneurysm, it has the ability to regrow. And I've seen that when I coagulated an aneurysm, worked on somewhere else and then gone back and seen it, re-expand some, so I don't think there's anything wrong with using it. Like I showed the case where you separated the aneurysm dome, you can easily coagulate it, but I don't like it as a form of really getting rid of the aneurysm.

- [Erin] Here's a question which is very broad is, do you think ICG has the potential of replacing intraoperative angiography, both Dr. Robert Spitzner and Dr. Anna?

- I wouldn't say replace, but I would say that it's supplanted maybe become the dominant way of checking our work. It's so quick and fast and shows you or answers the critical questions of patency, perforator preservation, dome refilling. So I think it serves our purposes in a way that's much more efficient. It's probably been a good couple of years since I've done an intraoperative angiogram, but I will say, have to remember that I'm 15 years into my experience, Dr. Spitzner is a many years into his experience. You need intraoperative angiography when you're starting out to learn and get yourself through some of those learning mistakes. So I think for the younger neurosurgeons, you shouldn't hesitate for a paraclinoid aneurysm that's real tough, a giant one, or some complex aneurysm to have that available and feel free to use it. Because again, I made a lot of mistakes starting out and I used intraoperative angiography to help myself through that learning curve.

- [Robert] You've got to stop asking him first because he's taking my answers.

- Okay.

- [Erin] So the other question that the audience is asking what's the limits of temporary occlusion for MCA, I assume, under burst suppression, versus-

- How about this, why don't we let Robert answer this one for ranks.

- [Robert] Or however long it's takes? I mean, I always amazed at that question because are you putting on temporary clips because you happen to have temporary clips and you wanna use them, or do you have them on there for a very specific purpose? And if you have them on it for a very specific purpose, they stay on until you are done with that component. There was a classic paper that came out of Texas Southwest, which basically said that at your tolerated occlusion for 17 minutes, and then patients who were longer than that got into ischemic problems, and those that had less occlusion time didn't. To me that was, it was totally opposite. If you had to have temporary clips on longer than 17 minutes, you were dealing with a much more complex aneurysm, which carries all by itself a much different morbidity and mortality. So ischemia time in somebody that is a burst suppressed a little bit cool is not one that should make you hurry or do something hastily that would not give you the very best result.

- [Erin] Let me put the question this way. If I'm doing an MCA, I just wanna look around the aneurysm more. I'm not really in a hurry. I just want a little bit of decompression of the aneurysm. I'm gonna put a temporary clip, but I can remove it in time to re-profusion and we apply that temporary clip. What would you say my time limit is in under those circumstance?

- [Robert] You are one persistent devil, aren't you?

- [Erin] You bet I am.

- [Robert] I mean, how long does it take you to look around?

- [Erin] I like the question?

- I would add that you can't control when to take a temporary clip off, but you can control when to put it on. And in my mind that temporary clip should go on when everything else has been done, that can be done safely without it. And so like for that, some of those aneurysms, you wanna take it to the limit. And so your last maneuver, whether it's dissecting that branch off of the dome or applying the clip finally, you to take it down at just that last maneuver.

- [Erin] Okay, that sense actually.

- [Robert] Seriously one thing that is critical naturally is where the temporary clip is. If it includes the lenticular strides, it should be on there for a very short period of time because of those are end arteries. If it's past the lenticular strides, and if you have all the time in the world. If it's proximal to the lenticular strides, you have a lot of time.

- [Erin] Troy, would you like to add anything, okay? The other question that the audience are asking is what's the temporary could strategy for basilar aneurysm clipping? And I think, and the other question, the same person is asking, why do you use combined endo and open approach for the same aneurysm in the same admission.

- So the strategy is what we've been talking about, use it at the very end, so that you can minimize your time. And then as Robert said before, where you put it as important, if you can put it on the lateral aspect of the third nerve, sort of lateral to the third and between the third nerve and the tentorium, that's the perfect place, because then it doesn't take away from your maneuverability within your triangle. If you can't do that, if you can't get to the basilar lateral to the third nerve, you just put it inside the carotid oculomotor triangle, but as low as you can get it. And then the only other thing is that, I sometimes like completely change the angle of the microscope so that I'm looking down the basilar as much I can, as I can. And that just gets it so that it's not in the same corridor, you haven't applied it in the same viewing angle that's the way that you're gonna work and apply your permanent clips on the neck.

- [Erin] Okay.

- [Troy] I would add a couple of points. for temporary occlusion for basilar aneurysms. That's one situation where drilling the clinoid posterior clinoid may get you even more proximal on the basilar and able to get that temporary clip out of your way. The second thing, I would say is that, I have had situation where the aneurysm really didn't soften very much after I've put a proximal clip on the basilar. If the patient has a dominant PCOM, you can put a clip easily, even on the contralateral PCOM if you choose a different window, the clips is gonna be completely out of your way. So you may clip between the carotid and the optic nerve while you're on the opposite PCOM, but still clip the aneurysm through the carotid and the optic window. I mean, the carotid and the oculomotor window. One other trick that I would mention on basilar aneurysms, and I don't know your experience with this, but I have found that if I open the falciform ligament on the optic nerve, the carotid will move over much farther, and I will get a much bigger window between the carotid and the third nerve. So I routinely do that.

- Hearing you talk, Troy, it reminded me of one other things when you look at your preoperative angiogram, one of my favorite aneurysms of basilar apex is where you can see the jet of blood flow that comes in and swoops around the back of the aneurysm. If you see that inflow jet that swirls around like that, that's an aneurysm that when you put a temporary clip on, it's gonna go soft. It's just remarkable how the aneurysm changes with the temporary clip. The other ones, they don't always like Troy was saying change much, because there's still a lot of collateral profusion that's keeping the pressure inside. But when you have that flow dynamic, it really is helpful for temporary clipping.

- [Robert] Erin I think I don't use many temporary clips and particularly not in the basilar artery. but I try to locate a place where I could put it. And we've got to remember that we now have adenosine, which really gives us that immediate softening of the aneurysm if we need it an order, but be able to place a temporary clip or to correct something. That's been a very nice addition. Don't use it often, always have it available. And when you need it, you can avoid putting a temporary clip that you might put otherwise, if you didn't have adenosine available.

- [Erin] And you haven't had any complications with adenosine, Doctor Spitzner, have you? Any complications?

- [Robert] With adenosine?

- [Erin] Yeah.

- [Robert] No.

- [Erin] Okay, so you feel comfortable using it, your anesthesiologist who does the dural response?

- [Robert] Yes.

- [Erin] For every patient or for particular patients-

- [Robert] I bet we use it, maybe one out of 20, one out of 30 aneurysms. So we don't use it a lot, only if it really is gonna make a difference. But I remember distinctly a case where the aneurysm was small, very broad based, and you couldn't put a clip on it. As soon as the adenosine was in there and it was soft, you could easily apply a clip and it, and it would hold. So I don't hesitate to use it because we only use it if we really need it. In which case we would accept the complications if we encountered one.

- [Erin] Michael how often do you use adenosine?

- Very rarely, but I can tell you, the last I did, this case is very fresh in my mind, it was a case of a vertebral aneurysm and the vertebral artery was completely calcified and atherosclerotic. So it didn't matter that we had perfect exposure, there was nothing that could close that inflow. And of course the aneurysm ruptured and the only way to get any control was adenosine. So even when you have the exposure, adenosine is the answer for the vessels that are rock hard and won't collapse.

- [Erin] Well, I really appreciate it. The only other question I have for you from my partner, Scott Shapiro, Dr. Spitzner, is there a company that makes this sucker with their lights at this time, is it commercially available?

- [Robert] Yes, it's a cogent or catalyst, one on the same.

- [Erin] Thank you, go ahead Michael please.

- Okay, let's roll this video. Troy this is a case that will demonstrate your last point, which is that for low riding aneurysms, this one's below the basilar apex on the basilar trunk. And this is an example where being aggressive with the posterior clinoid can really get you that exposure that you need. So here we are, we're working through liliequist membrane here. You can see the temporal lobe and, I was just preparing myself for posterior clinoidectomy and a transcavernous approach, which requires both an anterior clinoidectomy, and the posterior clinoidectomy. I think by taking the anterior clinoid out, you really expose the roof of the cavernous sinus, and it allows you to really dissect the third nerve all the way from the very beginning, back to the end. There's the clinoid coming out, your typical intradural resection. There's always some inevitable bleeding from the cavernous sinus. And I always find that that TCLB so useful it forms a nice little cast within the cavernous sinus. Eliminates all the bleeding from that point forward and now you can continue onto the posterior clinoid. So that's the dura over the posterior clinoid sort of the apex of that carotid oculomotor triangle. And by cutting the dura, you get to the bone of the posterior clinoid. You can drill that away. Here's the drill coming in. It's a very tight space and you have to remember that on one side, you've got the carotid artery on the other side you've got the third nerve. And so you've got no margin for error. You really have to watch where that shaft of the drill is going, where the tip of the drill is going. But as you do, you see that we now can push the clival dura forward. We can get further down into the posterior fossa. And this was a subarachnoid hemorrhage case. We're just working our way down, the back of the clivus to the proximal aneurysm. And finally, we're starting to get things into view. You can see that part of it is drilling the posterior clinoid and the other part is sort of pulling things forward towards yourself into view. And so, that's what it takes some times just to get this aneurysm into view. And there it is, it's sticking forward right there. You can see it's got that nice white tissue on healthy artery, and then the aneurysm projecting laterally, but we're well below the FCAs, we're deep into the under the basilar trunk here, and to get just enough window of exposure, having removed the posterior clinoid to see the tips and blades of that clip and to come across the neck. And our IC green confirms that our basilar trunk is patent or aneurysm is occluded, perforators are looking good.

- [Robert] Michael how about proximal control in that case?

- No proximal control. This is an example where you have to be confident in your ability and...

- [Troy] What I have done several times is to have my interventionist come up and put a balloon in the proximal basilar. Yeah, it's there.

- Yeah, you can stop it here. I don't think I saw that as a resident. I don't think I've done it in San Francisco. I don't know what others think. I just don't have a comment because I don't-

- [Robert] Well, it's one of the fellows that did a series of that and one of them ruptured the basilar artery and he blew up the balloon or control. I think that's beautifully done. I think you don't have proximal control, but you do have adenosine if you need it. I don't like the shaft of your drill because it's not covered. And so you have on several times, which can easily wrap around. And when you're next to the carotid and next to the third nerve, I think you need to have a little sleeve on that. The problem naturally is that it does make it a little bit wider, but there are sleeves that bring you down a little bit safer, yeah.

- Yeah, it's a good point. And if you use things like telephone pads or other things that protect the brain, those are very easy to catch-

- [Robert] Absolutely yeah. And then finally, you could use the ultrasound like Clauda to move that, although that has its disadvantages as well-

- Yeah, I was real keen on that. Actually you showed me on that concept and I used it for a while, but I find that it's not nearly as maneuverable.

- [Robert] Come on, Mike. It's the past no patients. I agree completely I haven't used it in years.

- [Erin] If I may ask a question, when we do temporary occlusion, do we need to raise the blood pressure? I think that's a sound idea to do, or do we need to have hypernoise somebody who's very interested in that question.

- Yeah, I do not hypernoise when I temporarily clip it. That's the question now.

- [Erin] And I'm sure Dr. Painter or are going to the same. We may raise the blood pressure just to increase...

- Yeah, so about the blood pressure, sometimes what you'll find is that the clips go on and those there'll be a change in the motor vokes or some that have sensory evoke potentials. And in that setting, you know that the patient needs help and you have to raise the pressure. If their collateral circulation is fine, you won't see any changes in the electrophysiology and you don't necessarily have to do it.

- [Erin] Michael, you brought up an excellent point. How often of you monitor what aneurysms.

- I monitor all aneurysms.

- [Erin] And what do you monitor.

- I do EEG and SCPs for all of them, because they're easy. If I'm worried about a motor track with antra choroidal, PCOM, basilar apex, anything that's gonna involve the motor pathway from top to bottom, then I'll add the motor evoked potential.

- [Erin] Okay, that sounds reasonable. Dr. Spitzner do you use monitoring finders.

- [Robert] I agree. Same, same monitoring.

- [Erin] So for every aneurysm patient-

- [Robert] Every patient gets EEG and evoked potential monitoring. Motor revokes for those where you are close to the tracts so the vascular supply goes to the motor tracts.

- [Erin] When you do a motor tracts you number every time you stimulate everything is shake. So you ask periodically for them and the entire field-

- [Robert] Yeah, sometimes I do it right when I'm clipping. Just to make it a little more interesting. I'm kidding, I'm kidding.

- [Erin] Make like a moving target for you.

- [Robert] If your burst suppress during temporary occlusion, then you may not....

- [Erin] It may not be useful. That's very interesting because Dr. Painter and I do not use monitoring at all. So would you-

- [Painter] We use for channel EEG for birth suppression

- [Erin] For birth suppression but I think they're talking about a more extensive EEG monitoring, aren't you?

- [Robert] No.

- [Erin] Okay, that's okay. How about SSEP we don't use SSEP. Is using SSEP standard of .

- [Troy] You guys have electricity in Indianapolis.

- Sometimes.

- Oh, okay. They got to turn those generators off because those machines do require for you to plug it in.

- [Erin] Troy do have any comments.

- [Troy] No Erin.

- [Erin] I wanna ask one question and I know this is extremely open-ended Dr. Spitzner. If you see patients around unruptured aneurysm, what's your overall paradigm about who should undergo clipping and coiling? This practice pattern of let's say 2015.

- [Robert] You know, Erin, my whole talk yesterday, of the vascular session was between clipping and coiling. And there's not an easy answer for this. I think if a patient is young, if they have an aneurysm that is of significant size, say greater than six millimeters and it's accessible and not feel that in my hands, the likelihood of a success is significantly better than 95%. I would offer them clipping.

- [Erin] Okay, Michael, do you have any thoughts there?

- You know, let's go ahead and roll that an example of a distal PICA aneurysm, and these are so nice. They're not so common, but they're really beautiful aneurysms. You can do a far lateral and just gently elevate the tonsil. You can follow the, the PICA out along its course. As you can see here, this one had a small sub arachnoid hemorrhage you can see thrombus internally and a very nice view here of the neck. This is just a, a temporary clip going on, proximally and distally. And this was very adherent to the amygdala. So on this one, I just transected the aneurysm just to free it from the amygdala. And that allows me to kind of roll the PICA away from the brainstem and then by lifting up on the neck of the aneurysm, you can just draw the neck up into the clip blades here and just nicely closed that. Now IC green, this is just an advantage of IC green, you see how faint that distal flow is in PICA, that's really not an acceptable amount of profusion there, which means if there's something despite it looking good extraluminally there's something not right about that. So the temporary clips go back on and I'm gonna apply this a little further up off of the neck, because what I need to do is get over that little chunk of calcium right there. I don't know if you can see that, but there's a little chunk of calcium and pinching that closed, it compromise the lumen. So I've got my clips sort of on either side. And now it doesn't look as good from the outside, but if you look from the inside, with IC green, you can see a very robust profusion of that display PICA. So again, I think it's very important to use IC green, very important to judge your success of the clipping by the flow and not the external appearance of the vessel.

- [Robert] I think it's very nice, a couple of points. Once you started cutting the aneurysm, you had no idea whether there was a branch of PICA coming up on the other side of that aneurysm. So you made the assumption that wasn't, which is not unreasonable, but which is not certain. And second of all, because there wasn't the branch, this was the kind of aneurysm that I think really involved the whole wall that you nicely demonstrated by your first clip application. This is a sick wall. And I was sure that what you were gonna do after that first one is you were gonna cut that out, and sew the two ends together. Which I can't believe you didn't do, but which you could do next time when it recurs.

- Yeah, so very excellent point. And that it may

- [Robert] And actually doing it the way you did. The only thing I would have added on. And I probably also would have just moved the clip because I'm inherently lazy. I would have placed some vortex around the vessel to embrace it so that it couldn't regrow.

- Yeah, okay.

- [Robert] Nicely done.

- Good points. I think I have that case. Why don't we call this one actually the next one-

- [Erin] Would you mind if I ask one, couple of quick questions, Michael, if you don't mind.

- Yeah sure.

- [Erin] Somebody is asking if you put a balloon or template what small control do you have to have hypernoise? I don't believe we do that. Just to answer that question because it's really quick and temporary.

- The answer is easy, yes. If you're gonna use a balloon-

- [Erin] I suppose, for a period of time Troy, I don't think we-

- [Troy] We have done it without fully hypernoizing the patient but we keep the time very short.

- [Erin] I agree. The other question is how often do you have new post-operative cranial neuropathies after basilar clipping?

- Rarely. I think Robert's point about preserving arachnoid of the third nerve is very on target. I think if you're gentle with the nerve and you preserve the arachnoid, you can expect there not to be a problem with the third nerve. If there is a problem, it's a temporary transient weakness that will certainly recover with time.

- [Erin] Thank you.

- Okay, let's roll this one. This was a sub arachnoid hemorrhage case. As you can see another PICA aneurysm, and again the far lateral exposure is just so beautiful for these. It's one of those aneurysms that requires very little in the way of subarachnoid dissection to get you down to your target. There's the obex and the fourth ventricle. And these, you just simply follow the vertebral artery. And by cutting the dentate ligament, it frees up things. You can get a good view of the vertebral artery just underneath the dentate ligament. There's your proximal control. And then you simply follow this out. So there's PICA. And if you follow PICA, proximally it's gonna converge with the aneurysm, which we see here. Yeah, this was one that previously was coiled and you can see that. So that's the distal vertebral artery. There's PICA coming out of the neck. You can see coils through the wall of the base of the aneurysm, but there was enough compaction in this one so that I could slide the clip alongside the neck there. These very oftentimes you need to think about using fenestrated clip to get sort of around the origin of PICA. There the tips you can see just beyond. This one had a little extra bleb on the distal side of the neck, which I just included in the second clip. So this one was a little unusual but I could simply use a straight clip and then a second clip for that extra piece. But you can see the PICA is nicely profusing there. And that, even though there were coils in this aneurysm, I was able to clip reconstruct it because of the compaction and the softness of the neck. And that's the view you get. Important to take out as much condyle as possible so that you really eliminate that obstacle of the condyle. So, this is that case, Robert, that you wanted me to do. Why don't we just pretend that this is that lady next year and her aneurysm has recurred. You can see the aneurysm there right in that caudal bend the PICA. Very nice and show him right there. Here it is right there. So, this is one that's just super nice for this excision reanastomosis. You can see inflow and outflow it's sort of an acute angle there. You also see the atherosclerotic changes in the neck of the aneurysm. And, you know, you could probably try and clip this and do some sort of a clip reconstruction, but instead what I'm doing here, I'm, transecting the outflow vessel here, right from the aneurysm. Here, I'm, transecting the inflow of vessel, right from the aneurysm. And when you roll the aneurysm around there and you look at it, you can see that atherosclerosis, you notice the complete separation of inflow and outflow, and that tells you, this is not your typical circular neck. Now you have two stumps of the PICA, and this is a really lovely bypass to do because you've got plenty of working space. It's a nice small vessel. It only takes about maybe five or six bites on either side, same technique as I showed you on that earlier case where you just put two sutures in one, on either side of the ends of the vessels. There you are at 12 o'clock and six o'clock. And now you have your two suture lines to fine, and this is gonna be just a simple running continuous suture from one end to the other. And again, this is just such a nice bypass. I really don't see the need to do and accept a lottery to PICA bypass almost ever. And then I can't remember the last time I've done one. These vessels are so nice to work with there are no perforators here to worry about. You can do these nice looping sutures here and snug them down, tie it down and it really is so straightforward. Here that trick of getting around the backside is just a matter of flipping your temporary clips, the other way, running the suture line back the other side, and you can complete the back wall. And because it's a small caliber artery, it's about six bites on either side. It doesn't take more than about 20 minutes or so of the occlusion time to get this done. And-

- [Robert] What's size suture is that, looks large?

- I use either 10 over nine and I can't remember what this one was.

- [Robert] I bet that's nine or?

- Yeah, it might be nine.

- [Robert] I have trouble with the smallest sutures too.

- No, but there's nothing more frustrating than when you do. All right, so the temporary clips come off, there's our connection and our IC green shows nice communication inflow to outflow. So there's our post-operative angiogram can't even tell that there was an aneurysm there. And I think that's just a really nice way to deal with these distal PICAs.

- [Erin] Great work Michael, I have a question for you. Why not measure, especially for the case where you had issues with ICG that flow within the vessel, you use the technology for measuring?

- Yeah, you know, it doesn't change anything here, you know that you need to replace flow if you interrupt the flow. So whatever it is, it has to be replaced and you're gonna replace it with this particular reconstruction. So I don't think it adds anything. Do I use doppler, yes. I don't, I'm not a huge fan of quantitative doppler, but for qualitative doppler, I think that's very useful in many situations.

- [Troy] I think the question was, on the case where you repositioned the clip, when you didn't like them, look of the ICG, you have used quantitative doppler, then maybe you didn't need to replace that.

- Yeah, you certainly could have.

- [Erin] Thank you.

- Okay, next case. All right, this is a thrombotic PICA, and I'm gonna demonstrate another bypass technique, which is the reimplantation. So I'm taking you through the different variations. You can see this as a very calcified aneurysm. The lumen is small, but the outside of the aneurysm is quite large. And so I'm not expecting to be able to clip this thing. And so we talked about end to end reanastomosis, we talked about side to side anastomosis in my earlier lecture. This is the third variation, which is a end to side anastomosis essentially reimplanting PICA. Here's the vertebral artery. You can see it kind of mushrooming into this fuse of form vertebral artery slash PICA aneurysm, there's PICA coming out of the base of the aneurysm. You can see the lower cranial motors draped over that. And so, the plan here is to basically take PICA off of the aneurysm. So I'm gonna permanently occlude the origin. I'm gonna temporarily occlude the distal PICA and this transects PICA from the aneurysm. Now, PICA at this point is completely free. And what we're doing is we're doing a transposition. We're taking PICA from the aneurysm in that super hypoglossal triangle, and we're moving it to the infra-hypoglossal triangle. And so now once PICA is free, we're closing the vertebral, you've got a temporary clip on the proximal vertebral. You've got a permanent clip on the distal vertebral, and there's our arteriotomy in the vertebral artery. And a reimplantation is really just an end to side anastomosis. We're making that fish mouth incision in PICA. I like to do the heel stitch first, so that the deepest portion of PICA gets laid down against the vertebral. And then the second stitch is on the toe. And now again, we've established our two suture lines and we go from one knot to the other knot. Again, running continuous suture over and over again. And once all the sutures are in place, we can tighten them individually from one end to the other. And you can see that the vertebral artery is a really excellent donor for this kind of a bypass because of the tolerance to that occlusion is very easy. The contralateral achieve a lot of these doing the work, and now we can kind of pull the PICA the other way, and we can do a running continuous suture on the lateral suture line here. And there's our reimplantation. So now PICA has been transposed proximally onto the vertebral artery. We take off our temporary clip and our permanent clip remains so that this is a reimplantation proximal aneurysm occlusion, and we've taken care of the flow in the pipe.

- [Erin] Dr. Spitzner how would you have managed this... Please continue to bring your questions to the text, to the phone number on the left side. Go ahead please Michael.

- Okay, next case. I wanted to show an intraoperative rupture case because I think these are always challenging, always tense. So this was a subarachnoid hemorrhage case you can see from that angiogram that this was one of those unusual dorsal surface of the carotid, almost blister like aneurysms. And so I was expecting trouble on this one and I found it. You can see that as we kind of peel the frontal lobe back a little bit, we're looking right at the dome of the aneurysm. The third nerve is there, there's the optic nerve, there's the backside of the dome. And that there's just this very fragile thrombus that's over the aneurysm. So I think it's about ready to be clipped at this point. So I put my clip on, and my idea here was to close that medial portion of the neck first with this fenestrated clip, and then apply an intersecting clip on the more lateral aspect of the neck. And you can see here that as I go to do that, there's really not much the aneurysm here. It's just sort of tears right through. So there's some are intraoperative bleeding. And so you quickly have to get your distal clip in position, and you'll see that there's still bleeding when I take that clip off. So the steps you go through are the same every time you you tampa on, dry the field, still bleeding, so we have to get control by putting a clip on the PCOM. So that's filling that aneurysm, despite proximal and distal control is the fact that PCOM fills forward. So very important to remember your circle of Willis Now, the aneurysm is under control. And as we flip this thing to and fro, we can see a little bit better than the neck. And so I'm just gonna, I need some more working space. This clip is proximal to the prior temporary clips, so I can remove the distal temporary clip. And now as we kind of dissect further, we can see there's just a big hole in the carotid. You're looking right down, intraluminal into the carotid. So what we have is this right angle clip that closes things back over, and transecting the dome so that I can see the tips of my clips a little bit better. And it's just a little bit of aneurysm that's left right at the tip. And I just put a couple what I call the picket fence clips over that little portion, and that that takes care of things. I can take the temporary clip off the PCOM. I can take the temporary clip off the distal internal and clip off of the proximal internal. And now we've got things under control, except for just a little something right there. There's one more clip on that takes care of things and a lot of clips, as you can see, but when faced with that hole in the artery, that's a much quicker fix than trying to do a bypass or trying to do some sort of a suture reconstruction of that. And IC green shows that we have a good patency in the internal carotid artery, good flow distally.

- [Troy] That might make a couple of comments on that.

- Yeah, sure go ahead.

- [Troy] These are very challenging aneurysms and what I always try to do when I clip an aneurysm like this is intentionally stenosis the carotid artery. If you don't take some of the normal carotid with the neck of the aneurysm, you're gonna have what you encountered there, the risk of inter rupture. The second point is, as your first clip went on it all to reconstruct, it was a heavy curved or right angle clip. And I always try to put that clip from proximal to distal rather than distal to proximal, because when you let the frontal lobe lay down, it can torque the spring of the clip. So if it's proximal to distal this spring, I will be resting on the skull base you won't have that issue.

- Yeah, good points. And I don't disagree with any one of them. I think to the latter point, you do what you need to do. Right-hander that might be an easier clip for a left-hander it might be harder, I don't know. I just, sometimes when you gather things up, you just need one clip to get it started. And whether it's proximal to distal or distal to proximal, sometimes you just need one clip to really get a good tooth in the aneurysm and bring it together. And then you can work out the details to finish the job. And, you know, I think those are very good points.

- [Erin] I have a question. First Dr. Spitzner do you have any pearls or dorsal carotid aneurysms, extremely challenging?

- [Robert] You know they are very difficult aneurysms and they have to be individualized.

- [Erin] Okay.

- [Erin] Proximal distal control, wrapping of cortex remains my favorite along with putting some cotton along the edges to seal the cortex.

- [Erin] Thank you. And may I ask if you're clipping an interior circulation aneurysm and the choroidal artery is extremely calcified and your clips are not closing, would you go to the neck or what's your preference there?

- I'm not sure what you're asking. If you're clipping the aneurysm and you lose the choroidal.

- [Erin] No, no, the choroidal artery is very calcified, and you can obtain temporary clipping by placing a temporary clip on the choroidal artery.

- If you can't get proximal control all along the super clinoid segment, then you have to get it somewhere. You can go to the neck, but it's rarely complete control. You're gonna get usually some collateral fillings from other connections between the neck and the skull base. And so, you know, that's a good place to start. It can stem the tide, but you do what you need to do.

- [Erin] Okay.

- [Robert] I think it is important that for any aneurysm that is proximal on the internal carotid artery, close to the dural ring, that the neck is always prepped. Doesn't mean you're going to open it, but it's one of those things it's like recording blood pressure. It ought to be just a routine of your surgery. And as long as that's part of your routine, then if you ever need it, you have it available.

- Yeah and I would add to that for these dorsal carotid, blister aneurysms, it makes sense to have yourself ready for a bypass, have a radial artery prepped and ready, maybe even have the incision made, if you think there's a very high likelihood, but it's better to be prepared and not use it than vice versa.

- [Erin] Do any of you use a sunt in suckling class?

- Yeah, It's funny. Dr. Wilson had a set of some clips that he kept. And when I got to San Francisco, the nurses asked me, should we keep these around? And I said, absolutely. And then about 10 years later, they said, you know, these have been in there for 10 years and you've never used one, should we keep these? And I couldn't say yes because I never used them. So my answer is that they're cumbersome clips. They make a lot of sense, but I think they're highly impractical. And when I've gotten into trouble, I'd do exactly what Robert said, which is to build a sling and to use regular clips, to essentially make at some keys clip.

- [Erin] Have you ever used them?

- [Robert] Yeah, I have. The trouble is that they're completely rigid. So one of the problems with them is the moment have them on, the pulsations of the artery can cut into the artery. So I think they serve their purpose. But with our writing clips that we have now with the ability to wrap around a sling that is a much more physiological way to fix that artery than it is without that rigid surrounding clip.

- [Erin] And also the technique you and Dan Beryl have described about cutting clipping technique has really saved me on two or three major occasions. I think that's a beautiful technique.

- [Robert] Yeah, it's a very useful technique because the cotton is strong enough to grab the rest of the vessel where you have a little tear on the neck, but still occluded and yet not rupture up the rest of the...

- [Erin] I totally agree. I highly recommend for, this is for vascular surgeons to read the paper and no surgery by Dr. Spitzner and Dan Beryl regarding cotton clipping technique. It's really so critical has saved my patients in multiple occasions. And it's extremely useful, do you use them, Michael?

- Yes.

- [Erin] Troy, any other thoughts there? Go ahead Michael please.

- Okay, let's turn our attention now to some AVMs. You can go ahead and turn the video on. This was a very unusual AVM on a medial aspect of the temporal lobe. And I want you to notice all of those really dramatic veins in the Sylvian fissure. This was a young girl, she was four years old and had been treated on three or four occasions with really aggressive endovascular occlusion of these large fissure. You can see some of those coil occluded feeding arteries there. So the approach to this one was essentially going transtemporal, avoiding the Sylvian fissure because of all those veins and getting into the ventricle and along to that medial portion of the temporal lobe. So this is where we're we are at now we're on that medial part of the temporal lobe. Here's one of those coils feeding arteries that you can see in the ambient cistern there, right at the tentorial incisor, and this was previously occluded, but still there were tremendous numbers of these branches off of the P2 segment like this one that came over the tentorial legend to the AVM. So this just shows how you define your planes. The feeders for these medial AVMs are largely medial. So as we open up the cistern, you can see the fourth nerve there at the end seizure. You can see these feeders coming over the edge, and it's just a matter of defining those different planes of dissection. I think one of the keys with this AVM is that the petrous segment is really an example of an uncas artery. So here we are coming on the P2 segment and what you have to do is you have to identify the main trunk and preserve that. And the trick in dissecting this is to skeletonize the artery. So as these vessels come off of the P2 and come over to the AVM, you have to individually pick them off one by one, as they work their way over. And so now we've essentially, dearterialized that medial plane by going across these little feeders off the P2 to one by one. And gradually what we're seeing, and this is just another big coiled vessel that was occluded earlier. We're defining that medial edge. You can now see, as you go through the coil mass, more of these little feeders on the medial side, and there they are. You gotta be really careful though that you don't inadvertently close off P2 because otherwise, you'll end up with an occipital infarct, but you can see the anterior all of this knife is starting to mobilize back, here some of those perforators that are normal going immediately, rather than laterally. And you just have to be diligent and not compromise the normal vessels. These are some more feeders now, more towards the back of the AVM. And now what we're seeing here is the basal vein of Rosenthal, which is our draining vein. We can peel that laterally. You can see some of these medial vessels, and now as Robert showed in one of his AVM cases, we can use into signing green to show that that vein, that basal vein of Rosenthal is not filling it's dark. The nidus is based on that Venus pedicle is essentially dead and you can see the P2 vessels on the medial aspect, normally, normal and preserved. So now we closed the vein. The vein can be tricky to close if you just cauterize it and you cut across and you can get some pretty torrential venous bleeding if you don't manage that carefully. So I used a clip here, came across the vein, and now we can pull this nidus out. And now you have after this thing comes out a very beautiful view of the deep there's the basal vein of Rosenthal that venous had a call that this thing grained into, and there's that nice view into the ambient cistern tentorial and seizure AVMs gone, venous hypertension is gone. A nice result for this girl finally, after many attempts of endovascular therapy.

- [Erin] Any comments?

- [Robert] I think we know very that an AVM, unless it's completely gone, continues to represent a risk of treatment. And I think one of the problems is the seduction of embolizing an AVM. And considEring it somehow as treatment, it is not treatment unless the AVM is completely gone and that's been demonstrated in treating, but the embolization only for AVMs. As Jack Marae announced to as one of the most aggressive endovascular surgeons in the world after he reviewed his series but they a 17, 18% complication rate with only 50 or 60% complete occlusion that he no longer does that. So I really do think that every endovascular treatment is part of the strategy, but it's no good until it goes all the way and gets rid of the AVM. And that has to be in combination with microsurgical resection.

- [Troy] Mike, can I ask a question? This patient was a four year-old you said?

- Yeah.

- [Troy] So in children there's potential for new AVMs. How will you follow this child?

- Yeah, that's a great question. We are very religious about our follow up in the pediatric AVM population. So I routinely get five-year follow-up angiography even after complete angiographic obliteration. And then, you know, she's four that would take her to nine. I think she even needs further surveillance after that.

- [Erin] What age do you quit?

- I think until they're beyond their teenage years and into their twenties, they're probably not, it's probably not safe to rest. I have had one patient of mine who I resected an AVM and it occurred. So I believe in that report from the Columbia Group, that these do occur in kids. Let me show this case, this was very-

- [Erin] One more question Michael I apologize. Do you use AVM clips? I personally use in smallest permanent aneurysm clip I can use for your AVM surgery.

- I do, I think micro clips whether they be AVM clips or any of the other competing ones are phenomenal. They, those small, deep feeders that are difficult to coagulate, the answer to those is the micro clip because they just will bleed and bleed the further you chase them with cautery, the deeper you get into white matter tracks. And you just have to stop that and use a micro clip.

- [Erin] What kind of clips to use.

- [Robert] I love those little AVM clips. I don't use a lot of them, but I do use them for example, as my bypass clips as well, because they are the smallest clips and they fit into spaces where the ordinary temporary bypass clips do not. So they should always be available. And they're much better usually for AVMs and the smallest temporary regular clips, just because of size and therefore have less torque. If you touch them with your sucker or other instruments.

- [Erin] One of our colleagues is asking how proximally do you resect the vessel that's been embolized Michael?

- As distally as you can. I think the best answer is that you wanna do it right at the AVM margin, it doesn't matter, or it doesn't serve any purpose to go more proximal to that because you can get some normal branch that's proximal to the AVM and supplying normal brain. So you just want to get it right at the margin.

- [Erin] Thank you.

- All right, this was a really interesting unusual AVM and a fun one because you can see, it's not really corpus callosum, it's a little deeper, it's actually below the corpus callosum that angiogram flew by a little bit too quickly to demonstrate that. But anyway, this is an example of the approaches that Robert was showing the interhemispheric approach that goes trans colossal with a head turned laterally so that the midline is horizontal. And we're basically going down the interhemispheric fissure to the corpus callosum, which is right there. It's that flash of white. It's always that different color, different from the typical cortical appearance, which is off-white. And we're gonna trace the intra cerebral arteries. Proximally you can see those two running in parallel, and they're wrapping down around the rostrum there, and you can see these little branches that come off of the A3 segment and dive into the corpus callosum, just distal to the genu. And here we are into the ventricles. So I sort of on the roofing, the ventricle going through the corpus callosum, when we get into the hemorrhage that's inter ventricular and taking out clot is a nice way to just buy yourself some room, decompress the brain and visualize your anatomy. So, there's the septum around one side of the ventricle there, you can start to see the ependymal surfaces with the veins. And here we are just going right along the top of the septum. And this was a nice one in that the feeders came off of the HCAs. And so again, like what I was describing for the P2 segment, this is an example of skeletonization or identifying the individual feeders off of the main trunk, and coagulating them one by one as you're certain they go to the AVM. So the normal trunk kind of lifts up off of the corpus callosum. You can identify these abnormal branches that go off to the side and dive in to the AVM, but it's important to preserve that distal flow and I'm dissecting from distal to proximal. So if you wanna preserve the distal flow, the way to do that is to get beyond the AVM and follow it around more proximally. And so, as we get down to the nidus, we start to develop these planes, you can see that arterialized vein down the distance there, more clot in the other side of the ventricles. And so now we're looking down into the other ventricle. And so the HCA gives some of the supply, but the other part of the supply is actually coming from below. It's coming from feeders off of the A1, and they very proximally A2, the to the anti perforated substance and up to the nidus. And so now we're just going around the front of this thing, attaching all of those feeders. And you can see in the, this is in some of those feeders that come underneath the nidus is really in the rostrum of the corpus callosum. And then we start to define these planes. Now, these AVMs that are in the ventricles, they're gonna drain into the internal cerebral vein. And the critical thing to think about in this dissection is where are the fornices 'cause that's where the morbidity is gonna come. Well, when you get morbidity in many places, not preserving the HCA is certainly one of the places, but you wanna be careful with the fornices. And as we dissect posteriorly and get to the foramen ovale, we have to be really careful about how we manage the fornices. So there the foramena and the fornix there, is just underneath my scissors. And it's really important to hug that plane right there. That's your eloquent plane. You've got to pull the AVM forward, stay out of the fornix as best you can, as they wrap around and dive into the foramen ovale, you just wanna kind of peel those off. There's the vein you can see that nice bluish color starting to darken. And that's when you know, you're almost home free. But again, you wanna try and pull the AVM forward, try and peel that away from the fornices and get those last feeders there. And then you can see now it's based upon that venus peduncle, it's pretty blue. And now we can just go across that vein. This is the internal cerebral vein. And there's our nidus. So you can see a nice picture there the HCAs, they go along the cingulate gyrus, nicely preserved, AVMs gone. And that's septa lavian.

- [Erin] Great work, Michael. Any comments?

- [Robert] I mean, it's one of those AVMs you salivate about because as he pointed out so nicely, when you have anterior cerebral artery feeders being the only feeders for the AVM. It's septal, so it's above the fornix and you know your anatomy, like you have demonstrated so beautifully. That's the kind of AVM that you feel like you're in control from the very beginning to the very end. If that AVM, would have had lenticular stray at our repeaters, it would have been an entirely different animal. Might've looked very similar, but it would have been much, much more difficult. Beautiful job.

- [Erin] I may ask, what is your post-operative blood pressure parameters after you move an arch in this malformation?

- It depends on the resection. I think if it's an uncomplicated resection where everything looked good and I don't have concerns, I just keep things at normal pressure. One rule of thumb in regards to the micro AVM clips is that if I use more than five AVM clips, that means that I've struggled and that I wanna consider not only keeping the blood pressure a little below normal, but maybe even keeping the patient intubated for a night.

- [Robert] Yeah, I think if I would use one and leave it there I'd be worried, but actually the same. You can tell whether you have some oozing and the removal of the AVM, where your risk goes way up in that case, I not only keep the blood pressure low, but I keep Amicar on board for the first 24 hours until I've seen the post-operative scan, the post-operative angiogram. And I'm absolutely certain the patient is stable. Then I withdraw the Amicar and let the blood pressure come back.

- [Erin] What's the exact parameter use blood pressure less than 110?

- [Robert] No less than 100. You know, it depends on the, obviously that patient's normal blood pressure, but if it's 120, then I bring it down to below a 100 for 24 hours. If I'm really concerned, it might be even lower and keep the patient asleep for a day. I think the Amicar here certain, but I have the impression that helps.

- [Troy] I have a question. Do you induce hypotension during the resection of the AVM?

- [Robert] Absolutely. Most of the AVM patients are young patients. The advantage of using hypotension is that you have less blood loss if you're having any sort of oozing makes the surgery go faster and then naturally you bring it back up to normal, or maybe even a little bit above normal while inspecting the bed and giving it a little time to observe.

- [Erin] So let's say most of these patients are young, blood pressures around 120. And once you have that parameter usually intraoperative...

- [Robert] Again, it depends on the AVM, but a systolic, a baby systolic of 70. If it helps make the surgery go faster and cleaner.

- [Troy] I'll ask both of you on, Mike you mentioned you don't do intraoperative aneurysms very often, do you do it on AVMs?

- Nope.

- [Erin] I think that you're gonna need one post-operatively anyways. And you know, if I find something on the postoperative angiogram, I don't have a problem with taking a patient back. I think for me, it's just adds an extra half an hour to an hour to the case. Doesn't spare the patient that high-quality post-operative angiogram. So I generally don't do it.

- [Robert] I agree sort of. I wouldn't hesitate to get an intraoperative angiogram if I've thought that the suspicion was high. I will frequently keep the room open and let the endovascular surgeon decide. And they almost always want to do it up in the suite because it gives you that better and possibly the final postoperative angiogram. But I must tell you that I have been wrong often enough so that I would not consider an AVM case finished until there was an immediate postoperative or intra-operative angiogram. I mean, that's where ICG doesn't help you at all because ICG only sees what you see and obviously if you see AVM, you're gonna take it out and it's the portion that's hidden from you.

- [Erin] We frequently do intraoperative angiogram after the resection, I would say almost routinely do intraoperative angiogram to assure everything has gone. The another last question which relates to this is do you always get a formal angiogram or post-operative number one? I assume the answer's yes.

- Yes.

- [Erin] Okay, Michael spectacular work.

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