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Welcome to SNI Digital Innovations in Learning in association with UCLA Neurosurgery. Linda Liao, chairwoman and its faculty are pleased to bring you the UCLA Department of Neurosurgery 101
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lecture series on neurosurgery and clinical and basic neuroscience.
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This series of lectures are provided free to bring the advances in clinical and basic neuroscience to physicians and patients everywhere. One out of every five people in the world suffer from a
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neurologically related disease.
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The lecture and discussion is on stereotactic and functional neurosurgery. The lecture is the 10 anniversary of the marriage of stereo EEG and stereotactic laser ablation, effects on the surgical
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practice of epilepsy
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Okay
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Robert E. Gross of the lecturer speaker is the speaker is Robert E. Gross MBNA Bowman chair and professor department of neurosurgery director and co-founder Emery neuromodulation and technology
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innovation center
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ENT I CE director translational
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neuro engineering laboratory director stereotactic functional neurosurgery
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and epilepsy surgery
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I better do that over well okay
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speaker speaker or the lecture or doesn't matter the lecture is Robert E Gross
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MBNA Bowman chair and professor of department of neurosurgery Director and co-founder, Emory Neuromodulation and Technology Innovation Center. Director, Translational Neuroengineering Laboratory.
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Director, Stereotactic Functional Neurosurgery and Epilepsysurgery from Emory
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University, School of Medicine, Atlanta, Georgia, United States of America Can you talk, can you talk, can you talk to that? Sounds for neurosurgery, looks like there's a reminder that the
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meeting's being recorded
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or later viewing. So it's my great pleasure today to invite our grand round speaker today, Dr. Bob Gross from Emory. Dr. Bob Gross has a very distinguished career. He is a professor of
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neurosurgery at Emory. and holds the MBA Bowman Endowed Chair in Neurosurgery and is the Vice Chairman of the Department, where he's been on faculty for about 22 years now. Dr. Gross is the
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Director of the Functional and Epilepsy Division at Emory, which is one of the world's most renowned Functional and Epilepsy programs. He has a number of awards and recognitions, too many to list
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here The NIH index is 42, his I-10 index is 77. He's been published over 7, 000 times and has been continuously funded by the NIH since 2004. He is the Director or Supervisor of over 99 MD-PhD
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students as Director of the MD-PhD program at Emory. And he's also a, a.
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close friend of my friend, Niko Yang. So I think a good measure of a great chair and division head is how well they get along with their colleagues and their trainees. And Nik, who's my very close
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friend and former trainee and many of yours former resident always speaks very highly of you whenever he talks to me. So Dr. Gross will be giving two talks this morning. His first talk will be on
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the 10th anniversary of the marriage of stereo EEG and stereotactic laser ablation. And the second talk will be of serendipity, science, and spiral staircases, lessons on life in the esoteric
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origins of functional neurosurgery. And with that, I'll hand it over to Dr. Gross. Thank you.
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Thank you. Thank you very much. It's truly an honor to be invited here. You guys have a great program. I think there's a lot of similarities in our programs, in the distribution of hospitals and
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the science and medicine. And
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you've been
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the spawning ground of some of our great attendings, like Rusty Rhodes. And of course, Nick Aoyung, who is a dear colleague, and I'm so happy to have him. So it's
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always great to talk to residents and fellows, if any of you are fellows. It is one of my passions is training students and residents and fellows and even down to high school students. So I think
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it's one of the most important, probably the most important thing we do,
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well tied to taking care of patients. So I thought I would talk about where we stand. I know you guys do stereo EEG and I know you do laser ablation. I've had the great honor to be at the forefront
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of this curve, having been an early adopter. And I think that
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is a role that I like to take. I do things in the laboratory, but some things that we do, in fact, probably the most impactful thing that I've done is just simply being open-minded to new
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techniques such as these. And I'll talk to you here about how we have married them together to truly change surgical practice in a way that we really never anticipated.
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So these are my disclosures. And some of them are relevant, in particular, Medtronic, who I've been working with for many years in this particular space. So we've really seen a transition of
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epilepsy surgery practice from the old to the new. Now, the old way in Europe for half a century and more, has been to do stereo electroencephalography as their technique for intracranial
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monitoring. And this ultimately leads to resection in a large number of the patients, but also talk a little bit about their role in
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laying the groundwork for radio frequency ablation. In the United States, for half of my practice, I guess at this point, we were doing sub-dural electrodes Craniotomies, you guys know what
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that's all about. And then our treatment was resection. And that's all we had. When we saw our patients in the office, it was basically, it was a pretty quick visit. I mean, Parkinson's visits
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were 45 minutes to explain what that technology was all about, but the epilepsy visits were 15 minutes. Like, take her to leave it. I don't have anything else. But we've really seen a change with
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both the advent of stereo EEG, which is now about 10 years older We started this in 2011. and some other sites like Cleveland started a couple of years before that. And so we've changed that
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practice a lot, but more importantly really is that we've moved from offering the sections as we and the people in Europe we're doing to having other techniques that are available to us like laser
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ablation, radio frequency ablation and neuromodulation. So I'll talk about how that has evolved in our practice and our use of this So I really see this as a rhesus peanut butter cup, okay? So
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it's two great techniques that when merged together are even better. And it ultimately leads to a completely minimally invasive approach, which is advantageous in some respects for the patients.
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Now, just to frame this and how different this is, we had a debate, I had a debate in 2009 at the American Epilepsy Society about more is more versus less is more. And I was assigned to the more
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is more category. And my partner, Jeff Blount, was assigned to the less is more category. And this was before we had any inkling about laser ablation, two years before. And I lost that debate.
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I'm part of the reason was I had acute laryngitis. But the other part was that I was talking to neurologists and neurologists voted eight, four to one. So 80 of them voted that less is more is
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better, even though I definitively demonstrated. And Jeff Blount and I published together after that, that more is more, okay? It leads to better outcomes with respect to seizures. But it's at a
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cost, okay? The more you do, the more seizure focus you might remove, but also the more of something else you might remove, which might be part and parcel of the seizure focus. So it was a goal
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of mine from that point, and before that, to try to eliminate the damage that ensues when we take out. either as much as we need or more than we need. So let's start just with stereo EG, because
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I know that you guys do it and I'll sort of run through it a little bit quickly. So this was the standard North American approach, big craniotomy, the bigger, the better. This particular
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situation, if I saw this situation, I would say, oh, the focus is going to be somewhere in this area that was uncovered by electrodes. And so, you know, I would cover everything And so that was
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somewhat of a, you know, that's not really a good hypothesis, as we frame it now with stereo EEG. My hypothesis is that if I leave an area uncovered, that's going to be to focus. So, but that's
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how we did it. And this was fraught with complications, subdurals, herniation, and that was not uncommon to have to take the patient back to the operating room. But at the same time, and dating
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back into the 1960s, this is what they were doing in Europe This was pioneered by Jean Tallerack. and Ben code, the neurologist that worked with them. And they took a different approach where they
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were attempting to sample all of the brain. So where does the word stereo EEG come from? I see it often quoted as written as stereotactic EEG because we're using a stereotactic technique. But
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that's not what the origin of the phrase is. It's stereo as in three-dimensional, like you're listening to a stereo speaker So it's EEG in three dimensions. And the way they do that is obviously
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having to pierce the prankum of the brain. And they would do that with this frame that was developed on the bottom left by TALORAC. It looks like a Lexel frame, but they would put a grid on that
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frame over here that you could see down here. I'm not sure which, okay, yeah. And they obviously had to avoid blood vessels. And the only thing they had at that time was there was pre-CT. even.
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So they only had angiograms. So they would shoot an angiogram on these patients. And then they would do this in a bioplane suite, basically, and they would look down the bore of each one of those
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holes and see if there was anything in the way. And if there wasn't, that's where they could put the electrode. And so that led to this orthogonal approach of coming in strictly parallel, all the
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electrodes are parallel. And that's how they learned how to do it. And that's important actually in how this technique has evolved.
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Now, it's just to point out that the patients in this technique, they would not get admitted to the epilepsy monitoring unit. They did not have the capability actually to do that at that time. And
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so this would be done in the operating room. Now they wouldn't stay in the operating room for two weeks. They would be there for 24 hours maybe at the most. And they would use drugs like pentylene
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tetrazol to actually provoke seizures, or occasionally cigarettes. So That was not the patient taking a cigarette break. Oh, I'm, though I'm 100 certain the surgeons did because one of the
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surgeon's menari died at the age of 40, 42 of lung cancer. These guys still unfortunately smoke to this day. But the
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patient's seizures were actually triggered by smoking. So they allowed him to smoke in the operating room without blowing anybody up. Now, the hallmark of this technique is not
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the stereotaxis per se. Actually, the stereotaxis is easy. You just stick it down that hole. The hallmark of this technique is correlating the anatomy with the electrical findings, with the
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clinical correlation. And so it starts with an understanding of the progression of seizures from interictal through the beginning of the seizure and how it evolves. Now, it seems self-evident that
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a neurological phenomenon that occurs at the onset of the seizure would be something. would tell you something about the onset. I mean, we know about Jacksonian marches, okay? If you see a
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Jacksonian march, then you're not gonna think it's coming from the occipital lobe. And, but it's not as, as inherent to people's thinking, certainly as neurosurgeons, we think that anatomy and
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physiology go together, okay?
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So, but neurologists don't often, minorologists don't often think like this And so, but that's the hallmark of this technique, is defining the semiology first and foremost. What is the first sign
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that you see? And then, use it, setting that up as a hypothesis, and you test that hypothesis with electrodes. And then you look at how it evolves. So this is part and parcel of the procedure.
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So it starts with a semiological analysis and, and goes from there. In comparison, the grid approach starts with a low bar hypothesis All we needed to do was say, Is this no? frontal lobe,
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temporal lobe, occipital lobe, parietal lobe. We didn't even have to say if it was in the insula or not, because we couldn't get to the insula. You couldn't put strip electrodes on the insula.
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One or two people had done that, but it's very, very difficult and challenging and fraught. Or maybe you said medial frontal. Oh, it might be medial frontal, it might be SMA. And so that's all
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you had to do ahead of time. But the work in this goes down ahead of the procedure. And it requires a good knowledge of theictal clinical symptomatology and a good knowledge of what the anatomy is
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that could produce that. So it's truly neurology, right? It's clinical neurology and anatomical neurology to be able to say that when a patient has a frowny face, okay, that's not something that
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just leads to an SMA seizure. That might be the onset and where does a frowny face come from? All right, so that's what the procedure really is Now, it's stumb with depth electrodes. from Jorge
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Gonzales Martinez, who really was the leader in the United States and bringing this technique over from France. And Jorge uses, to this day, a strictly orthogonal approach, which is what you see
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right there. But in comparison to what they were doing, well, actually, I'll cover this first. So when you look at how you, what the difference is and how much you're sampling the brain, it's
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easy to think that doing depth electrodes is under sampling and there's no question it is. That's the problem with any invasive technique is we're under sampling the brain. But how much are we under
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sampling it? And how much more is a grid sampling it or strips? Well, you have to remember that two thirds of the brain lives below the surface. And so by definition, using a grid, you're
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already deciding that you cannot see the onset in the two thirds that comes from below the surface. So I would be in situations where my neurologist literally missed theictal onset zone here because
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the clinical semiology occurs before we see an electrical change. But I would, I would say, well, we are in an area of the frontal lobe where the deep salsi are four centimeters away from the
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surface of the brain. So how could we possibly see the onset and just go for it and make sure that my resections always got down to the bottom of the sulcus. And what's so special about the bottom
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of the sulcus? Well, in fact, much of epilepsy begins at the bottom of the sulcus. Okay, we have we have bottom of sulcus focal cortical dysplasias, which back in the 90s and 2000s, we couldn't
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even see on an MRI scan because the MRI scanning techniques and we didn't have three Tesla was not sufficient enough to even see those. So then we would always just be going down to the bottom of the
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sulcus regardless. So it was somewhat of a brute force approach. Now with stereo EG, you see these electrodes, there's just little tiny electrodes, And this shows 12 electrodes going in. But if
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you do the calculation of the volume of tissue that's actually covered by those electrodes, it turns out that with 20 electrodes, you can cover 8 of the total brain volume, which is not
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insignificant. And we usually do around 15 to 20 electrodes. We try to go as few as possible. The more electrodes you have, the worse your hypothesis. So I'm implanting someone tomorrow who has,
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we're gonna put 24 electrodes in But I know that's because I can't even lobarize him or lateralize him. And so that's not a good sign. And so often we're actually doing a second stage on the same
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admission, rather than oversampling to begin with.
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So this is the way that Telerak and Banco did it with Alexa frame, but we have a lot of other techniques available to us now. So we have arc centered frames that allow us to do, to tailor each
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trajectory. This is extremely laborious, to have to change the frame three times and check it. And in fact, that's how we started doing it. And even when I started doing it, I couldn't even get
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X, I could get X, Y, and Z, but I couldn't get arc and ring coordinates because we do this in a Mohawk approach where we have to be able to come laterally in the stealth seven station, couldn't
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accommodate that. So I actually was setting up a phantom off of the field
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and setting up each target there, measuring the arc and ring that got me through the trajectory that I wanted and then porting that on to the first So really laborious technique. But there are
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better ways to do that. You have the FHC micro-targeting platform, for example, that you can custom manufacture ahead of time. The problem with that is that you can't change on the fly and you'll
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even see a case today where that would not have worked. But so I don't use that, but some people do. And then you have the robot. And the robot here, the rosa robot or the neuromate robot, and
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now there's the globus and the auto guide have really revolutionized our ability to do SCEG, literally have cut my cases into one-third this. time, which is really, really important. The first
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time we did this, and I know that you guys don't have the robot yet, so it takes a lot of setup. It's much faster now than we were in the beginning, but we bought the robot in and we registered.
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It took an hour or two to register, so we're probably planting our electrodes around 10 o'clock and the nurses and the squabs are in the OR, like, okay, whatever. And we put our first one in,
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drill the hole, put the electrode in, and then go right to the second one, you know, immediately, right over to the second one. Then that piqued their interest, put it in, into the third one,
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we got to the third one in the operating room, broke out in applause. They're like, we're getting out of here today. So it really has made things so much better, and that's part of it. Now,
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what you do in this is that you have to organize the brain activity in a three-dimensional way. So it's really four dimensions because you want to know where it is in three dimensions, but the
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fourth dimension, of course, is So you want to see how the seizure evolves in time
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and not just that it's in all of this space because it doesn't make sense to remove the area that the seizure is propagating to 45 seconds after it began. Okay, that it make what we're trying to do
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is get rid of the spark and you guys know all about sparks and fires. So the best thing to do is to put out the fire before it spreads And, and avoid the, the, you know, big type of surgery you'd
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have to do so we're, we're really with seg opening up the possibility of testing and identifying very small focal areas that are responsible for the onset. And if we think ahead, we might be
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realizing that perhaps we could take out less brain. If we can do that. And that's what excited me about this Now, the, so, so we're looking for this so called epileptogenic zone, and that is
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the zone of It's defined as the zone of brain that if you remove it, you will get rid of the seizures or it's the zone of brain that is necessary and sufficient to generate a seizure and we're trying
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to identify that and disambiguate it with the propagation zone And we also have with serioeg because we are down on the focus not recording it at the surface of the brain three centimeters away. We
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have eliminated for all intents and purposes the filtering aspect of the brain, whether that's truly how that works or not as a matter of debate, but the brain serves as a high frequency filter
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That's why scalp EEG does not give you high frequency oscillation, typically, but when you're down on the focus you can see all that high frequency stuff. This plus the fact that our EEG machines
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now can record at 2000 hertz, not 500 hertz or 200 hertz allows us to see this high frequency domain This shows you some of these high frequencies synchronizing this. charges at the 40 to 500 Hertz
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range. And in fact, we can now begin to pick up patterns that are better or worse prognostically with respect to surgical outcomes. So this shows eight different patterns on the left. And
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Fabrice Bartolome and his group and Patrick Cheval have done a lot of work at this. You can look at Fourier transform analysis, which really helps you to really see
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this in three dimensions, not just a linear time domain series. And it turns out this is one of the main determinants of seizure freedom. So if you look on the right figure, it shows the seizure
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freedom in blue and that is highly correlated with whether you get bursts of polyspikes or low voltage fast activity. It doesn't mean you're not gonna make people seizure free if you don't get that.
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So even on the right side where we just see rhythmic slow discharges, it doesn't mean we shouldn't take out the focus, But let's say you were balancing that against function.
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your decision whether or not to do an ablative or destructive procedure or to do a neuromodulation procedure. So this is all unleashed by stereo EEG. And so the reasons that it moved west and east
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because they're doing this now in China routinely and south, they're doing this in South America and even some in Africa. So it's because the robotic techniques really assisted us and assisted the
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stereotaxis. We understand this
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network idea and it takes a lot of work. Our neurologists have to go to course after course to really wrap their mind around the idea that epilepsy is a network. It seems self-evident, but it's not.
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It is more effective. I could show you data that shows that the outcome of surgery after stereology is more effective than the outcome after the subdural monitoring is no question it's an improved
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patient experience instead of being out of it for a week after craniotomy, three days, depending on where the bolts are and the patients are functioning fine. And we actually have a quicker
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experience, because the majority of patients are finishing a week now instead of on the order of weeks. And it actually matches with the other minimally invasive techniques that we have. So this is
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truly where this Reese's peanut butter comes, because at the very same time that we were adopting stereo EG, we had the advent of laser ablation. So this on the left here is Asha Gouda. So he is
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the former CEO of the company Visual Ace that started the Visual Ace technology on the right is someone from Montares that started it as well about the same time. So Asha Gouda was the CEO of a
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company called Visual Ace And Bill Hoffman from Visual Ace was, I'm sorry, Gouda is the founder and it's Chief Scientific
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Bill Hoffman was the CEO. Bill Hoffman had been trying to get into my office for about a year. And I was like, who is this guy? I don't want to talk to him. I don't want to talk to him. And then
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one of my neurologists finally arranged for him to be in my operating room when I walked in. And so I said, okay, who are you? And he told me about this laser technology. And I knew about the
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results from radio frequency ablation that had preceded this. And from Canada, for example, Andy Parent, about 10 seizure free rates in the mesial temporal lobe. And although I was interested in
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it, I learned how to do paladotomies. You'll hear about it in the second talk up in Toronto. And I was a big fan of it and was thinking about it, but I rejected it because it was not very
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effective. But then as I walked out of the office saying, yeah, I don't think so. Something stopped me at the doorway in the conference room. And I turned around and I said, you know what?
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Maybe you have something here. So we said about starting to use it and it was the most important decision that I've made. So this technique has compared to the lasers that I learned about and some
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of the older faculty trained with when we had a laser in the operating room. And the patient would say, I remember being a resident. And one of the patients said to me after I was a PGY2 and I
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consented her for a huge mening over section. And I said, do you have any questions? She said, yeah, I just have one question. What's that? Are you going to be using a laser? No, we're not
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using a laser. I mean, so we already discovered that they were pretty not useful But this is different because that laser was vaporizing tissue at the surface. It was a cutting tool. Lit is laser
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interstitial thermal therapy. So it goes into the brain. And it's a thermal therapy, not a vaporization therapy, which, of course, is temperature. But it uses medium exposure times, continuous
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wave lasers, and it gently heats the tissue and performs a thermocoragulative lesion, much like all other things that we do bipolar, monopolar.
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radiofrequency ablation. But it allows us to see the results as we're doing it. So why did I even get involved in this? Well, the answer is because of, although resective surgery is effective,
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okay? This is the only random, one of the only randomized clinical trials of surgical therapy for epilepsy. No question it's an effective therapy. 64 she's are free On call it 64 to 72. But the
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problem is, as I alluded to a little earlier, the collateral damage that comes in getting to the target. So this shows a paper from Germany, from Christoph Helmstedt, or as a neuropsychologist,
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looking at the results, the MRI results after a selective amygdala hypocampectomy. So it's selective. Why do we do selective amygdala hypocampectomies to avoid damage to the temporal lobe? It's a
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lot of old temple lobe.
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When we do it, we almost invariably are damaging the temporal lobe on the way in because you have to go through some brain to get there. And you could see the damage in the form of T2 changes and
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flare changes in the lateral temporal lobe, all right? So does that matter? Well, it turns out it does. The more damage you have, the more likely the patient will have damaged function related
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to that temporal lobe. If it's the dominant side, verbal learning has depicted here And in fact, if you avoid that damage, not only will the patient not decline in verbal learning, they'll
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actually improve in verbal learning because now they are not damaged and don't have seizures that are damaging the brain on a routine basis and impairing memory formation. So we have the potential by
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eliminating collateral damage to improve the patient over how they come into the office, not just get rid of their seizures. So it increases the therapeutic window, Maximizes damage at the target,
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avoid damage. damage associated with collateral damage. And it also decreases surgery associated morbidity, including pain and suffering and length of stay. So why did some patients be presented
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to me in conference? And then I said, Okay, we're gonna do a templeabectomy on you and I'll never see them again. Okay, they continue to drive even because they don't want the pain and suffering.
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And why are we so underpenetrated in how many epilepsy patients we take care of? It's because referring doctors don't like the pain and suffering 'cause they deal with the opioids afterwards and they
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deal with patients that are not happy. And maybe they have a deficit as Marty Morrell up the street in Nurepe says, you know, when someone in the room says, a seizure-free patient is a happy
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patient and she says, yes, that's because you don't take care of the patient for two years, five years, 10 years, 20 years when I'm dealing with their complications. why neurologists don't send
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them. And so by having more minimally invasive and more tolerable procedures, we actually get more patients willing to undergo open resections. When I said about looking for a control group for
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laser ablation, I said, well, let's just use the control group. All the patients we presented a conference that didn't go forward with surgery. And my neurologist said, we no longer have
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patients not going forward. Once you tell them about this minimally invasive approach And this allows neurologists to get in the game also. So outside practicing neurologists that refuse to even
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talk to me about surgery will talk to you about a laser procedure. It's different than a surgery in their minds. So this is really important. Now we're able to do this. Bill Hoffman could walk in
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my office not because Litt was new. In fact, it was invented in the 1980s but because it was now able to be coupled to something else, and that is MR thermometry. So with laser in the 1980s, you
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could only do the laser and then look at the results afterwards. But now, by using the MRI scan as a thermometer, it quantifies the phase change that's associated with temperature, and there's a
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linear relationship between phase change and temperature. So it can tell you the temperature change of any pixel in the brain. And so we can get a thermal map, and then we can integrate that
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thermal map So if you pick up that coffee cup and it's burning hot and you put it right down, nothing's gonna happen. But let's say you pick it up and you're going across the room and you realize
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it's hot because your neurons conduct like a dinosaur right in the middle of the room, and then you're like, oh, shoot. And by the time you get to the other side of the room to put it down, you
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burn yourself. So it's a time and temperature function. So our brains are not good at integrating the
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time temperature curve, but mathematically computer can do that. So it can. us how much damage has accrued and whether that pixel is likely to be necrotized. And so that's how it works and that's
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how come on the right side you see that damage estimate come up. So that's one of the critical features that was baked into this turnkey approach which we now can wheel into our MRI scanner. So
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there's many ways to get this electrode in just like this many or their catheter in just like there's many ways to get stereo G electrodes and in fact many of them are the same techniques. One of my
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favorites is the MRI platform up here which allows us to do the whole operation in the MRI scanner. Patient comes in goes to sleep, we put them in the scanner, we use this MRI targeting frame, we
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do the laser ablation, they wake up in the scanner, they go to the recovery room, stay overnight, some of them don't know why they're staying overnight and sometimes I don't either and then they
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go home the next day. So surgery on Friday back to work on Monday. It's a little bit of an exaggeration. But sometimes they get pain from these necrotic products, but it's pretty close. So Dr.
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Willy, John Willy, my former fellow and partner who subsequently moved on to Wash U St. Louis a couple of years ago. And I wrote this paper in 2014 on
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amygdala hypo-compotomy. So we call it stereotactic laser amygdala hypo-compotomy. You can see the good overlap of the damaged zone estimate with the actual damage that you see on a post-op scan.
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And you can see that we can do a pretty good job at ablating the hippocampus. So perhaps better than what they were doing with radio frequency in the United States, I'm sorry, in Canada before we
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started this. And in fact, we showed that although it's not as good as an anterior temporal lobectomy or selective amygdala hypo-compotomy, it's pretty good. Okay, so it's 53 seizure free. Now
35:13
that's all comers with MTS, which is known to have a better outcome We do a little bit better at - percent. Now, it's not as good as selective of a mcdole hypo campectomy, which is not as good as
35:24
ATL. So the less tissue we take out, the more likely we're going to not succeed in getting the epileptogenic zone. With about 12 patients that you do a selective on, you will make one more seizure
35:38
free with an ATL, and it's about the same with laser. With about 10 patients you operate on, you would make one more seizure free with a selective, and another one seizure free with an ATL. But
35:49
the good news is that you can do those afterwards. It doesn't burn any bridges by doing this first, and you have many patients that become seizure free, the majority that become seizure free
35:59
without going that far. This was verified by Cheng Wu at Jefferson in this multi-center retrospective series of 234 patients with exactly the same results as we were seeing in our study And this has
36:16
also been validated on - Now meta-analysis, there have been so many meta-analysis sees, we need a meta-analysis of the meta-analyses, but it also shows that that seizure rate is about 60 and a
36:28
little bit greater for
36:31
MTS. Now, the question is, does it actually, so it's less effective, that's great. You know, you can look at it and say, this is not as effective, why do it? So the question is, are we
36:41
actually doing better with respect to collateral damage? So Dan Drain, a neuropsychologist in our group, and us, and the group at University of Washington, published this paper in 2014,
36:54
answering that question. So we looked at our ATLs, these are patients that either had an ATL with me, that was a Spencer type anterior mediolus section, or I did a selective amygdala
37:03
hippocampectomy on half of those patients, or they had a tailored temporal lobectomy by Jeff Ojiman at UW. It didn't matter what technique of those three you got, 82 of patients had significant
37:16
declines And of the patients on the dominant side, 95 had evidence of naming deficits. And the problem with other centers often is that they don't test for this because this is highly penetrant.
37:30
And in fact, when I started doing laser ablation, the first 12 patients I did it on, I would approach and say, okay, we could do an anterior temporal abectomy or selective. I've been doing this
37:41
for however many years at that point 10, 15 years. We as a community have been doing this for 75 years and we have very good experience with it. Or I could do this laser ablation technique that
37:52
I've never done before. And all 12 of them said, I'll take the laser. So even the meningioma lady would have picked the laser. So now the 13th patient said, I just wanna have the tried and true
38:05
technique. And I said, okay, now honestly, I had a conflict of interest because I was by then training people how to do this and getting paid for taking my time to do that So I felt like I could
38:16
not tell that woman. No, I think you should have the laser because of my conflict of interest. So we did a left anterior temporal abectomy on her. That was about
38:27
2014. Eight years later, she's seizure free. Eight years later, she still can't remember the names of her grandchildren, okay? And she does not remember that she has seizures anymore. How are
38:39
you seizures? What's seizures? How are you doing? I'm doing horribly. I cannot remember my kid's names So I don't do left anterior temporalobectomy or selective because you get this with that
38:47
technique as well as a right out of the shoot procedure on anybody anymore. Now, what about with laser? None of the 19 patients we studied in this paper had any decline in any lateral temporal
38:48
function, naming or object recognition. So we appear to be changing the therapeutic window as we had hoped by avoiding that lateral temporal lobe damage. Now, what about
39:13
with memory? So Dan drain our neuropsychologist. said, I think we're probably doing better on memory. I said, Dan, the hippocampus is the memory structure. Did HM not teach us anything? And so
39:27
we, of course, took a look at memory. And here you see that in this series - oops, where is that?
39:36
You can see down here that there was no decline in memory in the AVLT, verbal learning, delayed recall, in the patients on the dominant hemisphere. So we appear to be doing better in memory as
39:50
well. And look at the non-dominant hemisphere. That's where we're improving memory by preserving the lateral temporal lobe, which can project to either side. We're able to preserve that memory.
40:01
So memory is a network function. It's not just the hippocampus. It exists. It's the registration desk of the hotel. What good would the hotel be without any rooms and just a registration desk?
40:11
And what good would the hotel be with all the rooms and no registration desk. So you need both to work.
40:18
All right, well, we also compare this to anterior temporal lobectomy and selective amygdala hyponectomy in 19 patients, done one technique, 19 done the other way. And you can see that on the
40:29
bottom left, the dominant open resections are the only patients that declined in memory. Whereas the patients with a dominant laser ablation had no decline, those with a non-dominant, dominant
40:36
open resection did not have any decline either And the
40:47
patients with a non-dominant slaw actually got better. So we're doing better at the target too because it's part of a memory system. So
41:01
this has been the evolution from the pen field procedure to dispenser procedure to the selective procedure to the super, arguably the super selective procedure. All right, well, I told you that
41:11
this was about both of those coming together. So how do we use these two together?
41:17
When we do SEEG and we identify the focus typically, what we'd be doing is with SEEG is taking out the electrodes, sending them home and bringing them back for a resection or for a laser ablation.
41:32
And that technique is shown here. We do that in the MRI scan, what have you. And that's the typical way we would do this. But there's many instances, this shows an example of an instance where we
41:45
brought the patient back in the singulate and you see that we can get a very nice ablation. This is probably this pointer, but so you see that we studied this patient in the singulum with electrodes
41:56
going in two different ways. Now this is not an orthogonal approach. You see there are orthogonal electrodes, but the advantage of having a robot and even a frame that's not a telorac frame is that
42:07
we can explore the brain with different techniques. We don't have to be strictly orthogonal because remember that was done for the frame. technique of using orthogonal electrodes developed from that.
42:20
But the reason was not because it's inherently better to sample the olfactory area 46 on your way into the cingulate. Maybe there's other ways to do it. So here we explored the cingulate in a
42:34
different way. And we brought the patient back and did a cingulate ablation, posterior cingulate ablation, as you can see on the bottom right The insula is another typical target where we're going
42:46
to bring the patient back, because the electrodes come in orthogonally or they come in obliquely as well. But I'll tell you in a second why it's advantageous to take the electrodes out and bring the
42:58
patient back and do an insular ablation.
43:02
But that requires a second admission. And that second admission, A, costs money to bring the patient back and B, you know, one of the most frequent questions that the patient asked. like what am
43:15
I going home with? Am I gonna get these shoes to go home? No, you're just trying them on. We'll send them to you in the mail later on. Okay, so they wanna take their shoes to go. So they wanna
43:25
have the whole thing done at the same time. And so they pressure us to do that and you'll see this in a second. So we developed a way to do this on the same admission, okay? So how do we go about
43:38
doing this on the same admission? Well, first and foremost was the use of so-called laser bolts. So these are bolts that were but are no longer made by ADTEC and are made by PMT that are larger
43:51
diameter. And so they can accommodate the larger diameter of the laser. So having identified your epileptogenic zone, you could say, okay, I'm gonna just slide this out and slide the laser down
44:03
in there. Now these bolts are actually quite big. And also with the ADTEC one, the diameter of the electrodes was dispenser style. They were not reduced diameter. So they were twice as big. So
44:13
it wasn't interested in putting in. 12 to 20 of these larger electrodes. But in situations where you have a very strong hypothesis, like in this patient who had a focal cortical dysplasia
44:27
down over here and had actually been previously operated, we had a very strong hypothesis. So I could put in these laser bolts. And then when I confirmed that hypothesis, I could do the laser
44:39
ablation right after that And so we take that out, slide the laser in, everything's done in one admission. But what are the options when you don't have laser bolts in place? Like what about the
44:50
lady I just told you about who's coming in tomorrow for a
44:56
stereology where I'm putting in 24 electrodes spaced out on both sides of the brain? I'm not going to put in 24 laser bolts. Okay, that would be not appropriate. And so we, what do we do in a
45:08
situation where we have regular laser bolts in place. So let me tell you about this patient. So she's a 49-year-old left-handed and right hemisphere dominant woman who we identified right
45:21
onset, low onset. So now the stereo EEG, as I told you before, the signature can be very highly prognostic. And for her, we had theta, we did not have any low voltage fast activity. So even
45:34
though I actually brought her back and put more electrodes in, we were pretty convinced we were not down on the target. So what sense would there be in a blading the area that is leaves out the area
45:45
that is the epileptogenic zone? So
45:48
we made a plan to do a resection, and that is depicted up there.
45:60
And what happened to the, some total loss for slide. I'm gonna just escape for a second, I might just be hidden.
46:26
All right, I have to share my screening in. Okay.
46:48
Okay, back to it. Okay, so this is the resection that we planned, and we went to see the patient, and I did my usual drawing on the board, describing everything to her showed her where the
47:00
electrodes were, and how this was the resection that we were going to have where. Okay. All right. Well, too bad. I missed this thing. So I had a nice little graphic there. We're upon the sun
47:13
said, we're not doing that. I said, but that's what we just found and that you're here to find out what you needed to have done. Nope, we're not interested in resection never were Take the
47:24
electrodes out tomorrow. You can do a laser blazer if you want. We heard about that. Can you do that? And then we're leaving tomorrow. So, you know, so this is a plan that we make between us.
47:35
We spent an hour and a half discussing this and the family. So some people are not ready to go forward with that. So I said, okay, well, let me see what I can do. I had the MRI scanner the next
47:47
day. or a DBS, and so I called the Medtronic person and said, can you get there tomorrow? Get on a plane now, get there tomorrow so I can do a laser ablation. Yes, had to fight with the MRI
47:57
scanner. Can I do another case after I'm done with the electrodes? That's a big deal for them. They want to scan the rest of the hospital. And we arranged to do this the next day. So this is what
48:08
we did. It shows you the electrodes that were in place And,
48:16
oh, here we go, here's my graphic, there it is. See, I wanted to use my emoji. And then what do I do?
48:24
Okay, so
48:27
we, now we didn't have the laser bolts in place. So how do I accomplish this without laser bolts in place? All right, so we developed a technique of pretty straightforward, actually. We just
48:39
remove the bolts So the bolts, it turns out, perfectly accommodate the diameter of the laser fiber. If you have a bolt in place that has a channel going through the skull, that acts as a
48:52
stereotactic surrogate. So we can slide the laser fiber freehand down the bolt, down the twist drill hole into the brain. You wanna do this with an MRI scanner so you can see it going in. And we
49:03
don't do this in certain situations where there's vascularity around there, that's fraught. Now, you need to have an MRI that's a sterile environment. Not everybody does this. And in fact, the
49:14
majority of people are doing this in a diagnostic scanner, where you can't establish that as a stereotactic environment. We have a stereotactic - we have an interventional scanner, which is a
49:24
diagnostic scanner, but that's outfitted as an operating room and functions as a sterile environment. So I can do this so you can see the frame on there now, or the coil on there. And this is my
49:35
fellow, threading each one individually through there. So we thread the fiber down there. We do the ablation. Then we go on to the next one.
49:44
And so this is how we did it in her and we were able to do the ablation, maximal ablation for each one of those particular electrodes. And this was her result at three years, and she had a
49:56
reasonably good outcome she had no generalized seizures for three years She does, however, continue to have focal impaired awareness seizures. For three years, every time she would come and I'd
50:07
say, let me do a recession. Okay, we can take care of that. And for three years, she refused to let me do that.
50:14
Finally, she came back after three years and said, okay, I'm ready to go I'm ready to do whatever you want to do. I pulled up my original picture of that rejection. I said, that's what I want to
50:27
do. So, so she allowed us to do that we bought her in and we did an e-cog guided resection, and she's after her supplement through motor area syndrome. She has recovered nicely and, and is
50:41
seizure free.
50:43
So this was a case where it was unplanned. So I had to make an audible at the line of scrimmage when I saw what the defense was up to. But we can actually plan these things ahead of time now so we
50:57
can begin with the end in mind. We know that we might be marrying this to a minimally invasive approach. So let me make sure that I have electrodes not just to cover the epileptogenic zone, but if
51:09
I have a relatively stronger hypothesis, like there's a lesion, or like there's a previously operated resection, then I'm going to put more electrodes in there so that I am in the zone where my
51:21
laser can actually help me out.
51:24
So this is a pre-genual singular case with a focal cortical dysplasia, where the decision is always going to be an open e-cog guided resection versus stereo EEG extra-operative mapping and subsequent
51:38
procedure but here we are able to do it using this technique. and can get a nice ablation like seen here and seizure-free.
51:50
So
51:53
there are cases where we want to do this and there are cases where we don't want to
52:02
do this. So these type of medial frontal cases are those that are lend themselves very nicely to this. Anytime we have a focus that's relatively near the surface or is in a vascularly acceptable
52:16
place, this is something we can do. I'm rarely, I'm never going to feed the laser in blindly essentially with in a vascular territory like the insula that might be dangerous. This is another case
52:30
of a stereo EG guided ablation of the SMA
52:39
and cingulate, just exactly the same way with electrodes coming down from the top. Now, what are some of the limitations of doing all this? So I've told you we can now do stereology on the floor,
52:46
and we can bring them right down to the laser scanner, to the MRI scanner, and do a laser ablation. But one of the problems with laser ablation is that it's a technique which almost invariably
52:57
needs to be done asleep. Because it's very different. You have any patient movement that jeopardizes the whole procedure. So you can't perform functional functional testing during the ablation,
53:10
like you can with an awake surgery. We have limits in how we can do this. Sometimes we can't get through the hole, for example, in the temporal lobe where the muscle is very big. It's impossible
53:22
to slide the laser fiber through the bolt in that region into the temporal pole. I told you about the list, logistical challenges in arranging to have a team at a time when you didn't know you were
53:33
going to need a team available. And so we have now an ability to fill that gap by going back to an old technique, that laser ablation has opened our eyes again too, which is radio frequency
53:45
ablation. So the Europeans have been using radio frequency ablation coupled to their SEEG for many years. So they recognize that they could just connect the electrode to an RF generator and ablate
53:57
without a thermistor, the target zone, and they've published this. But if you look at their outcomes, the seizure free rate is very low. So all patients, 18 of patients becoming seizure free,
54:10
72 with a transient benefit. Now, we can make use of that transient benefit, and I'll show you how to do that. But using this as a technique, per se, to make patient seizure free is not
54:21
something that we could reasonably expect, because there's only so big a radio frequency ablation we can make at the electrode sites. In the cases of a periventricular nodule heterotopia, RF
54:33
ablation may and often is sufficient, because the nodule is very small, We have good cover, and the Europeans have. that those patients tend to be made seizure-free at a high rate. Now, how do
54:46
we do that in the United States? So we have these depth electrodes which don't plug into the cosmon generator or any generator at all. We have a cosmon generator which plugs into thalomonomy
54:57
electrodes, but doesn't plug into these electrodes. So what we have to do is kind of shown here, we have to gerryrig it by taking a thalomonomy electrode, and we can't just put that down the track
55:08
because it doesn't fit and it's not a sterile field at the patient's bedside. What we do is we touch the thalomonomy electrode to the end of this electrode, basically plug it into the junction box.
55:20
And that's the role of the fellows is to stand there with these two thalomonomy electrodes jammed into the junction box.
55:27
So that's how we do it. This shows, by doing a radio frequency ablation of a peri-eventricular nodular heterotopia So after we mapped it, able to do that, patients been angle 1a ever since. But
55:40
there are other times when we can make even better use of radiofrequency ablation than with a non-functional
55:49
peri-ventricular nodulelet or utopia. So this is a patient who's an engineer who had a parietal focus and he didn't do well after I did a resection, we did a saunty on him, did an anterior nucleus
56:02
of a thalamus,
56:04
DBS, and then he came back for further management and we did depth coverage of his left parietal region. He's an engineer, his onset's in the left parietal region, he had naming difficulty with
56:16
one after stimulation. So I'm not gonna take this person down to the MRI scanner and do an asleep laser ablation and learn that I created a language deficit. The answer is no. So I can do this at
56:28
the patient's bedside now with radio frequency ablation where I could basically like doing open craniotomy with the patient awake I can progressively enlarge his lesion language testing. So that's
56:41
what we did. And we were able to first do a radio frequency ablation. He did well with that. He did not have any loss of function. And then I was able to bring him down to the MRI scanner and do a
56:54
much larger lesion that I was now comfortable doing because I established the safety of doing this with radio frequency ablation. He had transient naming difficulty, but unfortunately only became
57:06
angle three after that So that's a time, that's a way in which we use it to test function, all right? But we can also use it to test for seizure effects. So I showed you the slide from the
57:16
European group that 72 of the time they have a transient benefit, whereas only 18 of the time do they have a longterm benefit. So can we use that information to prognosticate about what the more
57:31
definitive surgery is going to do subsequently or to rule out a patient? So it's basically the final test of our hypothesis. by ablating it and seeing if we kick the seizures in the butt, all right?
57:43
So that's how we do it to check for seizure effects. So this is a 39 year old lady with the right hemisphere dominant, another right hemisphere dominant patient. She underwent grids back in the
57:55
early 2000s
57:58
by me. She was in the hospital for seven weeks and did not have a seizure before her husband said she needed to go. But we were able to get some interical activity which allowed me to put RNS in her.
58:11
She did fantastically with RNS. In fact, she was seizure-free for seven years. She testified at the FDA over there during the panel for RNS approval over lunchtime during the public part of it.
58:23
There wasn't a dry eye in the room. She probably was personally responsible for helping this thing get through, including the panel, they were not dry eyeed either. And unfortunately, after she
58:35
had a third battery change, She developed an infection. one of the shortcomings of this procedure. So I had to take the bone out and her seizures came back. So what do I do? So we came back later
58:48
and did stereo EEG, just actually through her non-bone flap leading skin. And you can see the depiction there. And I actually put this right down area six or premotor cortex because she was seizure
58:59
free with the strip going down that area. And we recorded on sets and I did radio frequency ablation and then ultimately saw the effect. I think I have that here. Yeah. So we saw the effect on our
59:15
seizures immediately. She was having four seizures a day and they went down immediately. So I validated that this was a good spot to do an acute ablation on. Did an acute ablation on her there.
59:26
And here's another marriage of the technique. So we also found that not only was this area, area six going down to the operculum involved, but she had a particular insular epilepsy as well. So now
59:38
the insula is not an area. You can see the electrode that comes down, actually don't have the
59:46
insula electrode showing here. See that in a second. The electrode that comes down into the insula, the insula is so fraught with M2 branches that I'm not going to slide this fiber down blindly
59:57
into this area. So what we did was we put a frame on her and we merged this acute technique going through the channels with putting a frame on and doing a de novo procedure and you can see the laser
1:00:10
ablation done there and she's done great. Now the difference between radio frequency ablation and laser ablation can be seen here. So the size of the lesion that we get with RFA is quite a bit
1:00:22
different than the size of the lesion that we can get with the laser. It has, you can get about two centimeters in breadth with the laser where you can only get about one centimeter with RFA So why
1:00:33
would I ever delay definitive surgery? in these patients, so why not always take them down acutely? So one of the reasons is the need for a different approach, like in the insula, if we need a
1:00:45
different approach, we're not going, I can bring the patient down to the MRI scanner to do a three-hour ablation through those channels, but I can't do a six-hour procedure, willy-nilly in the MRI
1:00:55
scanner without scheduling that ahead of time, so the logistics are very difficult. And then the other reason is there are times when we want to see the results of that ablation to prognosticate on
1:01:06
whether or not we can go on to, or should go on to a more definitive surgery. So this is a patient that has an insular onset and he had goosebumps, and we found very high-frequency onsets, and
1:01:21
then we were able to stimulate seizures at this particular onset zone with electrical stimulation. And to test whether or not he would be seizure-free, we did an RF ablation I'm going to bring him
1:01:33
back anyway because I'm not going to do it that at the same time. He was seizure-free for two weeks. He went from multiple daily seizures for two weeks. And then I brought him back later on. This
1:01:45
is another woman with an insular region that she had a very large periventricular nodular heterotopia. And only one small area turned out to be involved. So I did an RF ablation. She became
1:01:59
seizure-free. And then we never had to bring her back at all And this is another patient that had left posterior temporal onsets, that we did function testing, did RF ablation, and then waited to
1:02:13
see if she was seizure-free, planning to bring her back and do a greater surgery. And she was - that's the RF ablation - and she was seizure-free just from the RF ablation. So basically, we end up
1:02:25
oftentimes doing it just because we can, as well as if there's function, because we may make them seizure-free without ever having to do anything for them again. And then I think this is the last
1:02:36
case I have,
1:02:38
with the polymicrogyria, highly intact woman, with a large polymicrogyria
1:02:46
that we had
1:02:48
various hypotheses on, very big disruption. So we had a number of hypotheses. So we identified high frequency activity coming from just this small region of this, you can see all this
1:03:00
polymicrogyria going all over here. And only this small region seemed to be the area that was involved So I did a radio frequency ablation of that area. You can see the results that you can get
1:03:11
right there. And sometimes it looks quite frightening after we do it. But then it settles down to here. And she was seizure-free for two months. And then she had - And so I was very reluctant to
1:03:25
believe that this area was sufficient to make her seizure-free. But with a seizure-free interval of two months, that really validated that hypothesis I could bring her back and do a more definitive.
1:03:37
insular ablation, and she's been seizure-free.
1:03:43
All right, I'm going to skip over this in the interest in time, and I'll just show you the, this
1:03:53
is one of the points I wanted to make, and that is sometimes that we have to change the plan at the line of scrimmage. And this was a patient that I did an RF ablation in this region over here, and
1:04:04
she became seizure-free for a while, but then ultimately came back. We put more, I had planned to do a resection in her, but then decided that the better technique than doing an open resection on
1:04:17
her was to actually do a plan to head radio, laser ablation through orthogonal electrodes that would allow me to get to that supplementary motor area in a more effective way. And I could also test
1:04:29
for function at the same time. So I bought her back and this is the most aggressive utilization of this technique. So you can see this is all - we did 12 laser ablations through each one of these
1:04:41
electrodes. She had a very good supplementary motor area syndrome and has recovered completely from that and becomes seizure free. So sometimes we do this for function, sometimes we do this for
1:04:54
seizure effects, and sometimes we do it for no good reason except that the electrodes are there and it might actually work
1:05:02
So I'm going to go to my closing slide.
1:05:14
Okay, so we've actually now put together our series finally, so we've been doing radio frequency ablation. As my collaborator told me, I wrote this first version of this manuscript in 2015.
1:05:29
And we finally have it circulating, it's hopefully going to go out in the next week or so. So we've done radio frequency ablation on 62 patients now And we analyzed the results and we looked at
1:05:40
whether or not delayed having a seizure-free interval actually matters in terms of the patient becoming seizure-free from whatever I did subsequently, whether it was ablation or resection. And you
1:05:52
can see that that seizure-free interval actually matters. So those patients that did not have a seizure-free interval failed surgery at a much higher rate than those people that had a seizure-free
1:06:03
interval So now it gives us information, and I actually had another patient like that polymicrogyra patient at the same time, and I did this very similar RF ablation. and it didn't have any impact
1:06:14
at all on her seizures. So I brought her back and did a
1:06:20
DBS on her. So it can be very important in helping us decide whether or not to do that. And we also make a good number of patients seizure-free. So 16,
1:06:32
so there's a 17 out of, remember the total number, but it was 20 some odd percent of the patients became seizure-free just from the RF alone So they leave the hospital with the shoes in the bag
1:06:46
rather than having them sent to them. So let me just close up and say that, so we've now married together, laser stereo EG with laser ablation, with radio frequency ablation and with open
1:07:00
resection. We can mix and match these techniques. We can make a plan. We can come to the patient with that plan. We can evolve that plan with time at the bedside We can pivot to doing a radio
1:07:12
frequency. we can pivot to doing a laser at the same time, we can bring them back and do a laser, or we could bring them back and do a resection. Now, I've told you about all of those, and there
1:07:22
are some times when we just don't do any of this. When we have a patient with a clear focal cortical displeasure, we'll just skip the SEG altogether and bring them to the operating room, do an ECOG
1:07:32
guided resection, or maybe even an awake craniotomy. So we have so many more tools available to us now that allow us to have this discussion with our patients. It's no longer a 15-minute discussion.
1:07:43
It's more like a 45-minute discussion. But in Atlanta, at the end of that 45-minute, patients typically say, I'll do whatever you said, doctor. So it's probably because they're mostly just
1:07:55
confused by all this, as I'm sure you would be if I were to spend the time going through that. But it's become a very rich field for these reasons. And I'll just close by acknowledging my partners
1:08:06
and collaborators, all the neurologists that I've worked with over over the years that
1:08:09
obviously are part and parcel to this. everybody for your attention.
1:08:23
It's also for a wonderful child that I want you to put out in the TV to the audience that Bob has been a really a part pioneer in this area. But you
1:08:33
know, I think you need to modify your talk Yeah, right history, right, the question, right history, but you know that you
1:08:48
presented a picture that you know I see you were born in Europe, and really underserved the US really Because basically we're not dead, electoral, which is the real name of SEG here, but actually
1:09:05
pioneer
1:09:07
here by several people, including Paul Krendel, you know, who was a no and no assertion here, you know, in fact, the famous book terminal man, you know, he's about a patient who is operating
1:09:20
here at the NPI and escapes with death elected in his brain, of course, that was of course fiction. So there was a very strong tradition of so-called SEG in the US, both at Yale and UCLA and other
1:09:38
places. The only problem has a different name. It was called death electrodes. So at some point,
1:09:48
somebody came from Europe, and basically introduced the name SEG, OK? And one of the reasons that it became so popular here, because the neurologist now could become interventional cardiologist.
1:10:03
They could see the computer, and I've seen them do it, and say, I want to do it here, and I want to do it here, and I want one here, and I want one here. It was really fun. But you have to
1:10:13
remember that even in the series of Martinez, who has really been one of the main people
1:10:20
He has the 20 incidence of post-operative hematomas on the CT, just in a recently published series. So I'm very worried about your case tomorrow, Bob. And please give it a second thought. If you
1:10:38
need to put 24 electrodes in
1:10:43
the brain, then you don't really have a good enough hypothesis. So yeah, we have been using that electrode And very little, you know, sub-dural. But sometimes sub-dural grids are also important,
1:10:54
especially when you have a surface type, you know, of neocotical epilates in a certain area. And you also need to
1:11:01
do functional mapping. But I think in our experience over the last 20 years, you know, we have used perhaps 90 of the interventional or really deficit like your post-S-E-G, okay? So now I'm
1:11:14
writing, you know, a summary and I am forced to use the terminology S-E-G.
1:11:33
or there are always in the terminology depth select, okay? So please just take this into consideration in future talks, okay? The other thing which I'm concerned about is the usual eddy that when
1:11:33
you have a hammer, everything looks like a nail, okay? And I'm a little bit concerned, not in your practice, but in other people's practice that they are using laser ablation very freely So at
1:11:47
the first hand, you know, they don't really have a focal hypothesis. Point is, if I have a cortical dysplasia, I don't need ACG to really show me what's going on, you know? I'll go directly
1:12:00
either with the laser or open, you know, to really, so I think it's just a general, you know, warning in this general area that you really need to, as you pointed out, to really try to find,
1:12:14
you know, the right balance, otherwise, you know, the marriage of SCE. with other techniques may end up in divorce, so we have to be very careful about it. Thank you very much. All right.
1:12:26
Well, now I'm aware that I've come into your house. Okay, and as one of my my attending said when I was a resident, you come into my house and you criticize the color of my curtains. So, and
1:12:41
you're going to, I didn't necessarily detect a question mark in that statement, but I'm going to reframe it in the form of a question. And if you'll allow me, even though I don't have a memory
1:12:53
device implanted in my head, which I would probably need to remember all of that, I'm going to try. The first question to you is, at what point in the talk did you come in? Were you out to hear
1:13:03
from the very beginning or did you come in the middle?
1:13:07
So, I will first
1:13:11
nuance the depth electrode versus stereo EEG. I trained in Dennis Spencer's shop as well, so I put in depth electrodes as well. But the stereology, as I said in the outset, is an approach to the
1:13:26
patient, where you formulate, it seems obvious to us, especially as neurosurgeons, 'cause the neurosurgeons, anatomy, and physiology are the same. But for neurologists, not necessarily so.
1:13:39
And so it's an approach where you formulate the hypothesis of where you're putting these depth electrodes based on a very careful analysis of all of the information ahead of time. When I worked with
1:13:52
Dennis, yes, we put depth electrodes into the hippocampus routinely. And in my own practice, for the first 10 years, I would put depth electrodes in the hippocampus. Maybe I would put them in
1:14:02
the insula. But everything else I would cover with grids and strips. And so that is,
1:14:09
when we never had access to the part of the brain that went down below, and you could never use that high frequency analysis to really refine what you're doing, what depth electrodes in the field.
1:14:20
The stereo EEG approach allows you to do is to have a very focal ablation, which may or may not be better. Now, it's a balance between benefit and and risk, and we want to strike the balance where
1:14:34
we do just enough and not too much but this gives us the ability to really get into that equation and not do a resection even Jorge Gonzales Martinez couples his stereo with large resections, and
1:14:48
we're trying to get away from that because we're beginning to recognize the adverse effects of doing that Now it's so I disagree that depth electrodes is synonymous with stereo eg stereo eg uses depth
1:14:59
electrodes but there's different ways to use your tool, and
1:15:03
this is a whole different way for us people in North America to use our tool. Now I've probably forgot the middle of what you said, but I will talk about the end of it and that is the overuse and
1:15:16
over zealous use of this.
1:15:20
We have a very good center. There's, you know, probably I'm gonna argue 10 centers in the United States that do effectively use stereo EEG where it encompasses this whole approach. But I know from
1:15:35
the challenges in my very own center, I have two neurologists that know how to approach these patients and 10 neurologists that say, I don't get
1:15:47
it. And, you know, they're not going to the courses and learning about this. And so if you just implement this technique without the whole system of approaching it, and it's extraordinarily time
1:15:59
consuming, and it does not pay the neurologist. So you have to deal with the fact that these guys are losing money when they're on the intracranial monitoring service. So it's against great hurdles
1:16:09
that we have to implement it. In France, where they use this, they operate in Marseille, they do 20 patients a year. Okay, I do one patient a week So being able - scale and I gave this talk just
1:16:21
the other didn't talk like it just the other day and one of the questions was how scalable is this and it's not scalable it's extremely labor intensive and I share your concern of not only
1:16:32
neurosurgeons but also neurologists using this technique without the the right training. Also neurosurgeons using laser ablation without the right framing so I was in a medical legal case of someone
1:16:45
who used the laser on cavernous malformations something that I opened up I published the first two papers on it and it was his first case that he did laser ablation on and he laser ablated a calve mal
1:16:60
that he said was in the temporal lobe and it wasn't it was in the internal capsule and he made the patient tetraplegic which you know when I first got the case I was like how do you make a patient
1:17:11
with epilepsy tetraplegic the answer is she was hemiplegic from her calve malar section on the other side. So yes, this is a technique that can and will be abused. It doesn't mean we shouldn't be
1:17:23
doing it because we want to protect other people from people who will abuse it. It means that we have to educate people about both stereology and laser ablation and help them to figure out how to do
1:17:37
this. And in fact, I think the biggest challenge we have right now is figuring out how to do this economically in a system where this is extraordinarily laborious and costs a lot of money And that's
1:17:49
a challenge we still face. Thanks, Dr. Gross. Great talk. Thanks for coming down to LA. I have two questions. The first one's more philosophical. The second one's more technical.
1:18:01
You showed us quite a few cases of MR so non-lesitional epilepsy, MR-negative. And I wonder, you know, SEG and then laser and not having tissue for these cases. How important is - I mean, you
1:18:18
know, the oncology world, the most. or in question post-op is what the pathology show? For us, we kind of forget that conversation and not so much for the seizure-free patient, but for the
1:18:29
patient that isn't seizure-free and you're considering to go back and do more procedures, how important do you think is it to obtain tissue? So we're not just treating, interrupting seizure
1:18:44
networks as opposed to actually resecting the epileptogenic tissue. That's my first question. The second question is, I'm sure you've heard of porpoise calicidomies now with laser and
1:18:57
hemisprectomies now. And what is your thoughts on what is the boundaries of laser use? Do you think hemisprectomy is gonna be something that's gonna be done more commonly with laser down the road or
1:19:12
what are your thoughts on that? So first, and I can't remember your two questions. Um, so the first question is tissue diagnosis, I think tissue diagnosis is important, but you need to frame
1:19:27
what the tissue diagnosis does for your treatment plan would be the case I would love to have a diagnosis of an FCD. But the fact is that if they have an FCD to be, you know that you can see it.
1:19:41
Okay, it's not a malignancy question and you can see it And what you do to that FCD, it depends absolutely on the epileptogenic zone. You may not need to do stereo eg at all because you can see it,
1:19:56
but you would do it with ecog because you know that either part of it might be actually active and, or part of the brain that you can't see might be active So we tailor that. So that tissue
1:20:09
diagnosis of having FCD
1:20:12
2B doesn't impact your subsequent treatment because ultimately it's an electro clinical anatomical operation.
1:20:19
not to be, but it's cryptogenic, you know, then you can't see it anyway, and those patients don't do as well. So once again, your resection is going to be determined by the electrical pattern.
1:20:34
Finally, in low grade epilepsy associated tumors, those are the situations where I really wanna have tissue, but once again, the tissue pathology and the patient's presentation is going to declare
1:20:46
that Now, I may do, if I see someone with an enhancing D net or probable D net gangliong, then I will biopsy it. And that biopsy is going to be effective. It's a stereotactic biopsy ahead of time.
1:20:58
I don't need to see the cortical organization like an FCD, we're doing a stereotactic biopsy, probably not gonna help you. Maybe you get some balloon cells, if you're lucky. But there the
1:21:08
pathological diagnosis can be done with a stereotactic biopsy. And also your subsequent treatment plan has all to do with the behavior of that, both before you ever saw the patient. nuance at
1:21:20
seizures versus a 20-year history and what happens afterwards. And finally,
1:21:26
MTS, we know MTS when we see it. So the absence of a pathological diagnosis while academically, definitely of interest, clinically is not as much interest. And the second question was - Automy,
1:21:41
yes. So it's not the first adopter of calicotomy by laser Dan Curry was the first person to talk about it, yet to publish a paper on
1:21:53
it. I think we put him on our paper. And so John Willy in my group, who was my junior partner said, okay, let's use this for calicotomy. And I said, look, man, calicotomy is one of my
1:22:03
favorite operations only surpassed by hemisphere autonomy. So I'm gonna do it the old way. Plus, it was taking him like 13 hours to do this. And I said, I'm too old to spend that much time But of
1:22:17
course, the next calisotomy I did. I had a DVT. PE was in the hospital for two and a half weeks. I said, you know what, let me try it. And we also figured out how to do it faster. And so we
1:22:30
published our series of 12 or 14 calisotomies
1:22:34
last year, I think, and it's as effective as doing it open. We had one complication in there where we had used the robot to do it and targeting a distal structure immediately with a laser fiber can
1:22:49
be fraught with a robot you can get misregistration in that patient out of hemorrhage. So we have to balance all these new techniques against the risk and we have to realize like for cavernous
1:22:58
malformations we published a series of 19, 20 patients, no hemorrhages, but the next patient could have a hemorrhage. And so it could be, I remember your other question to talk now, and so it
1:23:10
could be that the hemorrhage rate is 20. So we really have to see, but there have been a number of series published with calicotomy. Now hemispheric I do not think is it? technique that lends
1:23:20
itself to laser. And plus, you know, we love it and we can do it open and the patients do great. There has been one published paper on a hemisphere anatomy in a kid that where they provide
1:23:34
adequate justification for why the patient was not a good surgical risk for doing it open. And so they did it by laser, it was laborious, but they successfully did it. It's not something I'm going
1:23:45
to adopt. And I don't think that's necessarily, and you have to be careful, that's right. When you have a hammer, you have to worry about everything looking like nails and being on the hypercurve.
1:23:55
And I think we're still on that hypercurve. And we need to be very, very mindful of that and judicious about it. And I'm just, it's our other free question about the 20 hemorrhage rate with SEG.
1:24:07
Yeah, the blood, you get blood 20 of the time. Subarachnoid is not all that uncommon. Okay, the question is how often do you get a hemorrhage that leads to a neurological deficit?
1:24:19
is 15, so it's not 20. It's just a matter of screening those patients and looking and seeing, having said that, I had a pseudoannurism. Dan Bauer is going to publish from StereoEDG, it was
1:24:30
absolutely from StereoEDG, but it's probably from using the monopolar coterie to open up the door or something we don't do anymore.
1:24:41
Yeah, I have one question about the gamma knife. The Marseille group published a lot apparently. And although the
1:24:49
pollutant clinic, I have one report in the past, which was very disastrous results. What's your opinion? And because there are a
1:24:57
lot of things changing in this area, if you can comment on that, I appreciate it. Yeah, I mean - Yeah, I mean, that is something that, you know, we were very interested in as being potentially
1:25:07
another minimally invasive tool In the temporal lobe, which is where it has been used, the rose trial, led by Nick Barbero, was a disappointment. Okay, I think it was 53 seizure-free in the
1:25:19
mesial temporal lobe with MTS. So that underperformed compared to the previous results, the Marseille group continues to do it, and you have to be aware, whenever you look at a clinical trial,
1:25:32
was that a test of the therapy or a test of the experiment? And so many clinical trials give you a result. which is not ground truth. It's possible the Rose trial that if you talk to John Regie,
1:25:46
he will say that these cases were not necessarily done the way he would do that. And I take him at his word, I've seen him do it. He's very, very careful. So the answer may not be in,
1:25:58
unfortunately failed clinical trials tend to set fields back by 15 to 20 years. But that's our status. Now the downside of the gamma knife for the mesial temporal lobe is that it takes 18 to 24
1:26:12
months for the effect to manifest. And with a laser, we can do it as safely, if not safer, because we're not getting that damage zone around the individual pathways. We don't get that nearly as
1:26:26
much. I'm not saying we don't ever get that, we do. But so it's as safe or safer, and it's immediately effective. So I think for the mesial temporal lobe, LIT has replaced gamma knife And then
1:26:37
in hypothalamic hammer tome is another great killer app.
1:26:57
or yamanife, same deal. So Dan Curry has published his paper with, he's got well over 100 patients now, and very safe, one complication of memory disturbance in someone that had a contralateral
1:26:57
temporal abectomy, but so it's very safe in his hands, not necessarily everybody's hands, but in his hands, and very, very effective. And again, that's an immediate effect, not waiting for two
1:27:06
years So I think that frames the difference between the radiation and the other question someone's invariably going to ask is then what about focused ultrasound? And you yes as 'cause, lesions small
1:27:17
in guys technique know good a, be will ultrasound focused think I,
1:27:24
it takes a long time to build up a big lesion. So it might take three hours to do a thalomotomy. How about a thalomotomy-sized ablation for epilepsy? We're talking about peri-ventricular nodular
1:27:36
heterotopias maybe even them, they're big sometime.
1:27:40
Hypothalamics, yes, I think that will be a good application for that. The temporal lobe, I don't have enough time to spend doing focused ultrasound of the medial temporal lobe, but maybe a
1:27:49
foreign economy. Just a straight foreign economy would be sufficient. In that case, there is a Weber-Krystner in UNC is doing AN to enter a nucleus of thalamus ablations with focused ultrasound
1:28:02
unilaterally, goes right down to the mammal ophthalamic tract. So it's really a mammal ophthalmotomy
1:28:09
I think that's a little bit hairy to me, but we'll see how that works out. But again, he showed me his three cases, and in each one of those cases, there was a reasonable justification for doing
1:28:22
it in those cases. So he's not necessarily being a cowboy, but doing what the patients sometimes ask for.
1:28:29
Well, here, one of the PGY2s here seems like one of the things that you're limited by with lot of lip is by the physics of using a single photon to do your ablation. and you talk, sort of talk
1:28:41
about, you know, you have to get transcortical and there's a lot of damage that happens with that. In research settings, people use two photon and even use four, four pi. Have you guys sort of
1:28:52
investigated, you know, possibly using something that has like a two photon with a longer wavelength and a higher peak power to essentially get more asymmetric ablations without damaging anything
1:29:05
that's above where you're trying to essentially get to? Yeah, I think any technique that you could, you know, what this does is it just opens up our thinking, again, to thermocurricular
1:29:16
techniques. And so any way that you can deliver energy into the nervous system and do it safely, you know, we haven't changed, you talk about the physics, there is physics of the laser because
1:29:27
it's straight. And that is a big limiting factor, but we haven't changed the physics or the biophysics of treating epilepsy. I'm not standing here saying that a minimally invasive approach would be
1:29:39
more of a - effective,
1:29:42
you have to take out the epileptogenic zone. However you do it, that's what you have to do. And so we have to use the laser in an effective way. And if it's not the right tool for taking out that
1:29:53
zone, then you don't do it. About a month ago, I had a focal cortical dysplasia in the posterior superior frontal gyrus going right up to the motor strip that was shaped like this. There's a
1:30:04
bottom of the sulcus. How are you going to do that with a laser? And why would you do that with a laser? And so the answer is no I won't do that with a laser. And so getting curved and
1:30:16
being able to do conformal treatments is difficult without multiple passes, but that's what people are doing. Multiple passes in the tumor field, for example. I mean, people putting four or five
1:30:29
catheters in to a blade. I think that we need to have new techniques. You've alluded to some possibilities of that And also having robotic devices such that. you can steer it on the way in and
1:30:43
steer it again on the way out. That's being developed at a couple of
1:30:49
centers, including at Georgia Tech. So yeah, we have to solve
1:30:59
the
1:31:01
problem of trying to get curvilinear structures with a single straight device. You know, we'll definitely look for evolution of these techniques. And I know people are looking at electroporation
1:31:07
and other things. And so I think in the future, yeah.
1:31:11
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