talking about the treatment of spinal cord astrocytomas in children, so thanks a lot. Thank you. So apologies for Graham. He was unavoidably delayed. He's only going to get in tonight. Unfortunately, I couldn't give his particular talk. Graham is far too good a politician. He's current president of the ISPN, and in fact, I see Mr. Harkness here. He should be giving Graham's talk as an immediate past president, but I'm much more of a worker, so I got a call last night to ask him if I could fill in. So I thought I'd talk about intramedullary spinal cord astrocytomas, if I may. I have no conflicts of interest. The history is an interesting one. I think of it in three epochs. So more than a century ago, the first description of a spinal cord tumor was made, and it was a funny operation in that the patient became quite unstable. They had to close up quite quickly and then came back a couple of weeks later, and the tumor had delivered itself, and they thought that was a great idea of how to deal with spinal cord tumors. Unfortunately, like many of us who have great ideas, our very next cases don't tend to follow that same pattern, and that was the exact same for them. So their second case didn't work so well. And then it followed a period in the 60s and 70s where people were generally quite pessimistic about taking out spinal cord tumors, which was sad because these are benign tumors in children, mostly. And then in the 80s, Fred Epstein started pushing the boundaries, and particularly with his neurophysiologist, Galvin M. of Vedran Delitus, and developed protocols to try to take out spinal cord tumors and brainstem focal tumors. And then I thought one of the most useful publications on spinal cord tumors was from Francesco Sala, who was one of Fred's and Vedran's fellows in the New York area. And he went back to Italy, and he was sent by his senior neurosurgeon, the head of his department, to learn IOM. And they came back to an environment where they were very, very experienced at spinal cord tumors. They had already done 300, and the introduction of these IOM techniques changed their practice for the better. So I thought that was a very useful publication. So there are various principles. I've got a few illustrative cases, if I may, and I'll hopefully demonstrate some of those principles. So we started with IOM several years back. Francesco Sala and Vedran were some of the people who helped us get going. And this changed our practice with spinal cord tumors. So firstly, just very quickly, the laminotomy and laminoplasty. We do the high-speed drill so you can put the bone back and avoid some of the deformities in children. And you can do multi-level, 10 levels, very quickly in a few minutes. You can take off the bone quite quickly. And then we trapdoor it and essentially put it back at the end of the operation. That works quite easily. Then we put it back in young children. We just put it back with sutures. We don't put any plates. And literally, if you come back a month later, it's all united. That's one of the amazing things about children. Just a couple of things about the spinal cord surface. I was taught that you can really crank up the magnification to get into the midline. And you'll see that point on the highest magnification where the small little peel vessels dive into the midline. I must say, I haven't been terribly successful with it. The midline is often very, very difficult to determine, especially with a swollen spinal cord. And so ultimately, you end up making a little bit of a guess about where the midline is, based on where the dorsal root entry zone is on both sides. So if you've got a wide enough laminotomy and you can see that, then I tend to go just in the middle. There are a few somatosensory techniques to try to identify the posterior columns on either side, but those are quite difficult to do. The rostral and caudal cysts are very common in pediatric spinal cord tumors. Those are very useful because it's a very clear delineation of when you've gotten to the top and the bottom of the tumor, even if the tumor is not terribly discreet. So that's one of the caudal cysts, in fact. So just a couple of illustrative cases. This one happened very early in our experience. It was an 11-year-old girl who presented with neck pain, some sensory symptoms in the right arm, and very mild right shoulder weakness, power of 4 plus out of 5. But also, importantly, a slight change in her voice. And this was a tumor. It looked like a JPA, but it was ventrally placed. It was very high up, and she had very large syringobulbia, which is obviously causing her change of speech. But it was an illustrative case for us because our adult colleagues were quite pessimistic about the operative results in this setting because it's so high. And their experience in the past had been so poor, and they had made a call that there's no way that you can operate on a tumor like this without making a patient worse, and she was very well. Fortunately or unfortunately, the very next day she developed a respiratory arrest. So then she was ventilated. We operated in an emergent way. So this is putting the epidural electrode. This is one of the IM techniques. It's very, very robust. It gives you something called the D-wave electrode, which is much more robust just than the motor evoked potentials. And so this is opening up the spinal cord. We use an iris knife. We get to the tumor, and you slowly just progressively debulk it. This is what the scan looked like post-op. And this, again, is just a really good illustrative case in that the spinal cord tumors in children can completely display the motor pathway. So at the end of surgery, you can see on the axial, at the end of surgery, all the way through to ventral pier, which if you don't have the confidence of good MEPs and D-wave electrode, will fill one with some fear. But this was her about six weeks after surgery, completely neurologically intact. She went home about four days post-surgery, and she was completely well. And now she's many years out. It's a benign JPA. The tumor hasn't come back. A slightly different illustrative case, five-year-old girl, no neurological deficit with mild scoliosis. So again, these tumors can be quite challenging because they have a very long sagittal extent. You know that they're benign. On axial, it can be very difficult to distinguish what is normal cord and what's tumor. But the same principles apply. Opening up the dura, visualizing the cord. Sometimes, as in this case, a bit of the tumor presents itself. That's a good place to go in. And then finding the rest of the tumor. And then just slowly, as long as the MEPs and the D-waves are okay, you can just use your suction and sometimes Kooze, if necessary, until all the tumor is out or until you get run into problems with electrophysiology. So again, a cord that looks like that, again, we'd normally fill one with some anxiety. But again, if the IOM is okay, you've got confidence that she's going to go back to the post-operative recovery room and she's going to be fine. That was a scan post-op of the tumor left. And this was her about three months later. Still got mild scoliosis. And unfortunately, many of them do present with scoliosis that has to be dealt with separately. Another illustrative case, a 13-year-old boy where, when you look at his medical record, he actually appeared to have symptoms since he was a year old, but just really, really slowly progressive, which again illustrates the fact that these tumors are often just so benign, so indolent, and very, very slowly growing. But also very difficult to image because of the scoliosis. So you get little images of the tumor expanded spinal cord. And this is what it looked like intraoperatively. Very, very gliotic margin, probably because the tumor has been there for such a long time. And again, tumor art and the scoliosis, of course, has to be dealt with. And we have pediatric orthopedic colleagues who do that. Just one more case to illustrate a slightly different lesson. So a younger child, spotty enhancement of a tumor in the cervical region. Sometimes the cord is really, really badly rotated. And you can't get to the midline. So sometimes what we do is go lateral to the dorsal root entry zone and find little skip lesions in between the dorsal roots to get into the tumor. And then very lastly, these are motivoke potentials. So this was one of our patients. These are motivokes on the left and the right, respectively. And then I don't know if you can see, this is the baseline here, but this is the showing up in that year. So this is a completely flattened out motivoke potential. And typically what we do with that is then just take it easy, relax, stop whatever you were doing, whether it was resecting or just manipulating the cord, get the blood pressure up, irrigate, and just give it a bit of time. Come back after five or ten minutes and do the motivoke potentials again. If they return, then you carry on. If they haven't returned, you wait a little bit longer. If they still don't return, we close up. And if the patient's well post-op and doesn't have a deficit or mild deficit, that improves. You come back after about four weeks and we continue the operation. And very often those motivoke potentials will regenerate themselves. And then very last, so in summary, IOM has changed our practice, but it's more than just a handbrake. A lot of people think about IOM just as a handbrake of telling us when to stop, but actually if the motivoke potentials are okay, it gives us the confidence to press on, which is very useful because these are benign tumors and they can be cured. If the surgeon's going to use intraoperative monitoring, you really need to know what it can and what it can't do. You can't just get a neurophysiologist in. You need to be familiar with it. And there's no harm in coming back. If you run into trouble, you close up and you come back. And then very lastly, for the tumors that go up into the spinal cord, if you're interested, these are ways of monitoring the lower cranial nerves. So this is electrode around the endotracheal tube. And so we put that over the endotracheal tube and we intubate a patient with that, with electrodes at the level of the vocal cords. And then the way that we monitor palate and tongue, so these are little hook wire electrodes. So you stick the needle in there and then you pull it out and it leaves a very, very fine electrode in the soft palate. So we run two in the soft palate on either side and then we put two on either side of the tongue as well. And they're very, very fine electrodes so they don't give any hematoma problems. Certainly we haven't had any. They just really, they can be a little bit tricky to place and even more tricky to keep in place. You've got to really strap it down because most of these patients, you're going to turn them prone to operate on them. All right, Anthony, any questions? I'll stop there. Thank you. Thank you. Those were great videos. Again, we appreciate you staying on time. Questions from the audience. If people could please use the microphone. While people are going to the microphone, just if I could see by a show of hands in the audience, how many of you operate on spinal cord tumors in children? You just raise your hand. And of the people who operate on spinal cord tumors, how many use intraoperative monitoring for those? So pretty much everybody. So it's become, I wouldn't say a standard, but it's become commonly used, it sounds like. That's great. And how many people use both SSEP and motor evoke potentials? And how many use D-waves? And would you, just as a question, would you stop for D-wave changes or only motor evoke potentials? Yeah, so one of the useful things about that publication from Francesco's is that it was a clear decrement. There was a clear distinction between motor evoke potentials being present and absent and D-waves being present, not only present and absent, but present, decreased but above 50 percent, and then decreased below 50 percent. And if the motor evoke potentials drop out, you may or may not have a deficit. But if your D-wave is maintained above 50 percent, that deficit will be temporary. And you're pretty confident about that. But if it drops below 50 percent, that deficit is a permanent one. So it's a very useful adjunct to just MEPs. Great. Thank you. Please. And the second fluency of these cases, all astrocytomas? Yeah. So those were astrocytomas. The pandemomas are much less common in kids, and they tend to be a little bit easier because they're more discrete. But these are JPAs, polymyxoid astrocytomas. Please, in the back. Yeah. It's a good presentation, but I think you should avoid comments like adult neurosurgeons are afraid of operating on this area because spinal cord tumors are done by both adult neurosurgeons and pediatric neurosurgeons with the same competency. So I think that kind of comments are not good. Thank you. So that wasn't a generalized comment? That was a comment about our specific practice? No, but even astrocytomas in adults are done by adult neurosurgeons. Oh, absolutely. And they should be done with the same approach. Thank you. Please. I just had a look at the show of hands of people doing the intramedullary tumors and using monitoring, interrupt monitoring. I don't use monitoring for multiple reasons. We have a huge list, and it tends to slow you down. I needed your comments on that. And we've seen that often the monitors go to sleep, and then you're worried. You think your patient's not going to wake up well, but that's only temporary. So then you just wait, and it doesn't really serve your purpose. So I guess once you're looking at the tumor and you know what tumor is, I think it serves the same purpose if you don't use monitoring, like your comments. So, yeah, so that would be controversial. I'd take a completely different view to that. I think one of the things I liked about the SILA article was that they went back to an environment that had already done 300 spinal cord treatments, and it changed their practice. It does slow things down. But I think when the potential mobility is leaving a patient quadriplegic, then every little bit helps. And I don't mind slowing down in that context. It certainly changed our practice. It's changed it for the better in terms of the margins of resection, so we've been more aggressive, and in terms of our neurological outcome. I think that's in most circumstances. I think the key thing, though, is having the surgeon have a very good understanding of monitoring and the neurophysiologist. So the problem is if people aren't equipped, then I think the adage of a little bit of monitoring is worse than no monitoring is a good one. So if it's going to be monitoring, it's going to have to be proper monitoring. I have a series of over 90 cases, and I think our results are just as good. Sure. So albinobricolose series was 300. There's a technique that we use that is probably different from the one that I've seen here on the video. We try and open it to the cords in minute spaces under high magnification. We try and get the midline, but we're not really worried of the midline. And we make sure that we don't handle the cord. So when the surgery is pretty much done, the cytoarchitecture of the cord is pretty much maintained. I call that technique the micromyelotomy technique. I've sent it to the journals, but unfortunately not accepted because we don't use monitoring. Sure. So there are people who don't do monitoring. I think they are increasingly in the minority. But if you've had good results, well done to you. Thanks. In the back. Great talk, Tony. Thanks. What is the age limit for when you should be confident that the D-waves and the mono-evoke potentials are already there and you can do this? So what is the lowest age? So I don't know what the lowest age is, but as a general principle, Andreas, you make a good point. It's more difficult in young children because of the unmyelinated fibers. So as children get older, and in adults it's, in fact, quite easy. But, of course, it depends on age and it depends on preexisting neurological deficit. So the youngest child I've done with a spinal cord tumor, probably about six months. But we do lots of children with tethered cords at that age. And so if you know what you're doing, you can generally get pretty robust signals. Tony, really nice talk. So at your shop, what do you do mostly for a grade 2, you know, infiltrated vasocytoma? Say you get in there and you really can't resect. There's a lot of residual. Do you radiate? Do you watch them? Chemotherapy? What is the general strategy? Yeah, so it does depend on the age. So if they're younger, then we give them chemotherapy first. If we haven't been able to resect at all. And I find my preoperative assessments, and I'm sure you're the same. My preoperative assessment is not necessarily very great. You've got to be there and see. But if we haven't been able to resect them all, and those are generally the ones that don't enhance very well, and they don't have that discrete border, if they're young, we give them chemotherapy and hold them until they're eight or nine, and then we'll give them radiotherapy if there's residual. Last resort. Do you at all hold off on spine instrumentation just to allow subsequent imaging? Or do you use more titanium rods for that sort of thing? Yeah, so we try to hold off. The point you're making is that it's just a mess having a litter. But if the scoliosis is progressing, then sometimes you just can't hold off. You've just got to be pragmatic. And then it depends on how far post-surgery you are and how confident one is about the completeness of the resection. Great. Thank you very much.

intramedullary spinal cord astrocytomas

children

spinal cord tumors

surgical techniques

intraoperative monitoring