Good morning, everybody. OK, so I'm just going to get right to it and just go down this list. So about the first four or five slides, I just have a list of things to point out. So I'm going to talk about asleep and awake mapping. And from the asleep point of view, I think it's reasonable, and I still do asleep motor mapping if and only if the lesion is not in or directly contiguous with the functional cortex. So in those cases, I will have those patients awake. The currents that I use typically under general anesthesia vary between 6 and 16 milliamps. Now that's using the technique, and I'll describe it in one of the slides, the bipolar electrode. I use simultaneous EMG. The body temperature is very important. Be very careful. You know, a lot of times you walk into the room, the patient's uncovered, and there are like 34 and a half. So they don't map very well if they're cold. I don't like to use propofol because the propofol can prevent depolarization, and it's not a good drug to use under general anesthesia for mapping. So it's one of the reasons why you can't stimulate the cortex. But I have it in an IV near a vein in case there's a seizure, and I can't break it with the ice ringer solution. We talked about the stimulator working. Check the batteries. When this whole stimulator was put together, there's a battery check on it. Make sure that those green lights are on. I replace the batteries pretty frequently. You can evoke a muscle twitch if you're near a muscle. Be prepared to use strip electrodes if your bone flap is not near that area. I'll show you examples of that. The current that we use subcortically is basically the same current that I use cortically. And then on occasion, if I cannot stimulate the cortex, I will go up to 16 milliamps subcortically very carefully and try to drive that, but that's only in that setting. And of course, we use the ice ringer solution. And I'll show you a picture of that. Okay, on the awake side, I think the key thing here, you got to know your customers. You got to be careful how you select your patients. I would say in general, it would be extremely unusual, no matter how big a patient is or no matter what their issues are, it's extremely unusual, as you'll see, to not be able to get them into the operating room to do a case. So don't use that as an excuse. The type of anesthetic drugs are critical. I'll point this out. Whether you use an LMA or not, it's dealer's choice. Local anesthetics, very important in terms of the skin block. I'll show you a picture of that. Focused exposures, that's how I like to do it now, because usually if we're doing two cases a day, we don't have time to do the more extensive mapping, but that's just me. Motor and language tests will go through, and of course, the different subcortical and cortical techniques. Now a few things about the surgical exposure, because if you're doing tumors, you're going to obviously do redo tumors. So again, I like to do very focused exposures in the newly diagnosed as well as the redo tumors. And I'll just say once again, I don't have a problem acting on negative mapping. Let me come back to that later. For the redo cases, again, from a skin incision point of view, I'll do whatever it takes. I'll T the incision. It doesn't really matter, but the key for me is the first operation I do on a patient, the bone flap is bigger, and then each subsequent operations, I telescope it in, just like the dura, because you don't want to open the dura from outside where you made your initial incision because of the scar tissue. So you just got to keep going in. I block the middle meningeal in the awake setting for focal pain. As you'll see, there are no rules to open the dura. Do whatever you need to do to get the exposure. For the redo cases, if the dura is adherent, be very careful. Avoid opening large extents of dura in the redo setting. On occasion, when the dura is stuck to the brain, I'll map epidurally just to try to go down and see if I can find the cortex. Study the arterial distribution distally before ever sacrificing it. Sometimes you have to do that, but be careful. I'll show you a picture of that. And then we're going to get into the issue of veins, how to deal with veins when you're doing mapping cases. These are the parameters that I use, and essentially, I'm in the Ojiman School. I've spent my whole career working with bipolar, the bipolar electrode using these settings with the constant current generator. So there are two schools you heard about yesterday. There's the bipolar group. There's the monopolar group. I'll show you in a certain circumstance where I will use monopolar stimulation. But in the awake setting, it's rare if I ever go over 4 milliamps. I think you'll hear from Hugh. He probably stays around 3 milliamps. Same current cortically as subcortically. I know we talked about current spread yesterday, but the reality is we've never done a study to see how far the current spreads in white matter. In the monopolar world, it is about 1 to 1, but in the bipolar world, we don't know. We think even at the highest current, it's probably less than a centimeter, but we just simply don't know. We talked about the body temperature and then the EEG. Okay, so here are the things that I go into the OR with. Accurate set of numbers. Your nurses prepare these. Always use a little centimeter ruler so that you can go back and look and see what you've done. In the asleep setting, this is the EMG technology and technique that we described in the Journal of Neurosurgery in 1999. Again, the goal here is don't have the anesthesiologist pick up the drape and try to see what's moving. Verify it with an EMG. It's easy to do. As far as the strip electrode is concerned, we use four contact strips. You see the strips going in under the dura, but be careful. The strips will come out as the brain sags, so take a wet clip and put those wet clips on the strip to the dura so that it doesn't move, and that way, you can't blame the movement of the strip on not being able to stimulate the patient. This is what I mean about a limited exposure. This is a case where you'd look at this and you'd think you've got to have a big dura exposure, but this is the only area that I exposed. You look at this and say, how the heck can I map through this? Well, you can map anything that's exposed. This is all the dura that I could open safely in the left temporal lobe. I mapped what I saw. Didn't have any issues. I went in, and then you see on the right the postoperative scan, so you can be pretty aggressive with a small exposure. As far as the veins are concerned, I just don't mess with trying to strip the veins off the dura. I'll just shred the dura. I'll cut the dura. I'll leave the veins there. If there's a vein going somewhere that I think is functional, I'll put a temporary clip on it, and I'll look at the brain, make sure it's not swelling, or I'll look at some potentials if I'm using those to make sure that I'm still able to stimulate, and then I'll take the vein, but usually, I don't take the vein. If you look at this scan over on the right, I'm pointing, on my right, your left, I'm pointing to this. This is the vein of lobae, so I just essentially took the dura off here to expose the tumor, took the dura off here, left the dura on the vein of lobae because there's no way I was going to strip it off and not injure the vein of lobae, and then I did the mapping at that point. Sometimes after you do these resections of a tumor, again, you see a big hole afterwards. The veins sag down. I've gotten a couple cases early on, a venous infarct, so what I now do is I take a little piece of gel foam, I put it under the vein, up against the tissue, and I drop a drop of TisSeal on it, and that prevents the vein from sagging. We reported that, I think, last year. This is what I mean about doing a resection and preserving the on-passage arteries. Just watch where they are at all times. Leave those intact. Sometimes you open up the brain, especially in older patients, and you see this very thick arachnoid. Well, what do you do with that? Well, basically what you do is you put your bipolar stimulator firmer into that deep arachnoid. You can open the arachnoid, but the reality is you're not going to get very far. If you see a milky arachnoid, just push that in a little bit. Don't pierce the arachnoid, but just push the bipolar in so that you're touching the brain. Here's the mapping technique with irrigation that Carl Sartorius and I described several years ago. Basically what's going on here is that every time I stimulated, I got a seizure. The resident is irrigating ice water while I'm stimulating. That's basically the technique. Now you can wait until a seizure occurs, and then you can ice down the cortex if you want, but if you have one seizure, what I recommend you do after you get that under control is go back and you can map just to have somebody irrigating to ice that cortex down. It doesn't affect the cortical function. In the asleep setting where you've got the EMG set up, this is the subcortical technique. You basically take the stimulator, and what I like to do is I'll put the Cavitron in one hand, stimulator in the other hand, and I'll just walk down the area that I want to resect and stimulate at the same time. That's basically how I do it. You can see I'm not pushing the electrode into or through the white matter. I'm just touching it. Now here's where monopolar stimulation I think can help. This was a case I was doing a few weeks ago, and I was trying to do an aggressive resection. I was way beyond this area. You can see the navigation point, how far I am away from the enhancement. In the red, that's the motor track on DTI, but with the bipolar stimulation, I was still not getting any activation, and I was already up to about 16 milliamps. In that setting, you heard the parameters yesterday, I used a single monopolar stimulation using this paradigm, and the current spread in the monopolar system is greater. It's like sending out a bunch of sentries into the brain to look for the motor system. You can look for it several centimeters away with the monopolar stimulation, and then you can come back and fine-tune that with bipolar, and I think Lorenzo is going to get into this in much greater detail. From the awake point of view, when can you use it? You can use it every day. You can use it on every case if you want to. It doesn't matter, left, right, front, back, brainstem. You can use it in the peduncle, down in the spinal cord, but for the most part, obviously, I'm not going to try to keep those patients when I'm down in the brainstem awake per se, because you can get good motor responses in the asleep setting. But in the normal awake environment, and I will on occasion, I've kept patients awake where I'm taking out a tumor in the peduncle. It's a little bit uncomfortable for them because of the dural stimulation around the incisor, but basically, you have to know your customers as to whether they can do it. This is a study that Eddie spearheaded, and again, if you ask the question, why do we do awake mapping, And this is what I asked George yesterday. It's because there's extreme variability in the data. And this is exactly what this study shows. If you look at the probability of finding function up on the top in red, you see the distribution. And this is based upon all of the stimulation maps that we took. We took those places where we got the specimens and where we got the numbers and we harvested them, meaning we put them into the brain lab navigation, we saved it, and then we went back and analyzed all that data. And then you can also see the variability of where you find, for example, speech arrest sites in the lower area. So the bottom line is you're gonna find it where you think you're gonna find it, but you're also gonna find function where you don't think you're gonna find it. And that's the variability. This is the variability of anomia. So you can see the probability of finding it is where you would expect to find it in that so-called Wernicke's area, but the variability exists all the way around, even including the frontal operculum. So you have to map it. And the reason we found in this study that Eddie did that you can find this, and I'll get into this in a minute, has to do with the fact that when there's a chronic process, unlike epilepsy, when there's a chronic process like a low-grade tumor in a portion of the brain, there is the potential for plasticity. And these are the kinds of cases where we saw the greatest degree of probability of function, meaning function can move over time. Okay, so these are the basic principles. In the top left-hand corner, you essentially draw your skin flap out, and then you're gonna block that area right around it. So basically, I make a box in terms of the block with the lidocaine and marcaine around whatever incision I draw it on the skin. I use a nasal trumpet in patients who snore. We talked about the cold irrigation, and there's the 30-gauge needle which goes intradural to block the middle meningeal artery. You raise a little wheel. I'll show you a picture of that on a video. Basically, for me, and you're gonna hear differences all through the day, the only thing I'm really interested in is object naming and reading, because for me, that's the most important two tests to try to predict whether a patient's gonna have a post-operative deficit. But again, I freely admit that I will have patients with subtle, very subtle deficits in other cognitive functions that don't necessarily bother them, but it prevents them from being dysfunctional at work or in the family. That's very different than what you're gonna hear the rest of the day. Those are the two functions that I like to map. Sometimes, if, depending upon where I am, in white matter pathways, if I wanna get much more detailed information and look for very paraphasic errors, I can use a picture word interference test. I can use a sentence generation test. If I'm in the right parietal lobe and I'm doing the case awake, and a patient plays a guitar, you can have them play the guitar in the operating room. So sit down with your patient in the clinic. Ask them what they do. Ask them what's important for them and map that function. You can map that function by having them do that in the operating room or to use the tests that are commonly recognized in the literature for those functions. Now, Sean Jumper, who is with me, he's now in Ann Arbor, does the mapping there, put together this study with me, and this basically goes back over the awake operation. And I just wanna take you through this because I think it's important. This represents for me about currently now a thousand, just over a thousand cases of awake procedures, and I wanna just show you what I've learned in this setting. So yesterday, we talked about a number of issues that can cause failure of the procedure. So one of the reasons for writing this paper was that I wanted to look at the prior concerns I had. So for significant mass effect, when Rich asked that question last night, what I like to do is I like to go in there asleep, internally decompress the lesion using whatever functional mapping I have preoperatively, and then come back when the brain's relaxed and do a second stage several days later and complete it with an awake operation. I've done that because I've had a couple patients in my career herniate on the table. You saw that one picture Mary showed you, the brain swelling. When it happens, that's the end of the problem. I mean, it doesn't get better. For obese patients, I just use an LMA. If I know that they're very anxious, I put them on medications beforehand. The youngest patient I've ever done awake is 10. I've never had a problem 10 or over in the adolescence. If it's under 10, I'll just stage it with a grid. We talked about intraoperative seizures. Have propofol in an IV six inches from the vein. If you can't break the seizures with ice ringers, and then you say to the anesthesiologist, who could be the resident who's on there doing their emails, you know, give the propofol, you're gonna wait too long, and the patient's gonna come out of pins. So at the beginning of the procedure, I make sure the propofol is six inches from the vein in an IV, loaded, ready to go. If they're a smoker, I put them on cough suppressants for a while. You gotta watch out for that intraoperative nausea. It's pretty easy to deal with with medications. If it's real bad, I put a patch on the night before. We talked about the reoperation-focused procedures. And if a patient's severely impaired pre-op, I'll challenge them for five days with high-dose steroids and diuretics, and see if I can improve their function to the point where they're at least 70 or 80% intact in terms of naming function. So, and just my point of view is I like functional imaging, but I never, ever, ever say it's inoperable based on functional imaging, ever. Enough said about that. Okay, my technique is the asleep, awake, asleep technique. So put the patient asleep, wake them up to do the mapping. If you need to do subcortical mapping, keep them awake, and then put them asleep for the closure. This is just a quick little video as I walk down through this. I use intraoperative corticography, and then I map the function of choice that I'm interested in. I'll go through this animation in more detail in a minute. And then we use the LMA if we need it. The technique has evolved. When I started with George, we didn't have any propofol. So it was nasty because the patients complained about the drilling of the bone. Now we have the propofol. We have the dexmedetomidine. So it's a much different scenario now, and we use the LMA if we need it, but I have used an LMA less than 10 times in my career. As far as the technique is concerned in terms of exposure, we talked about how I now do more focus exposures because of the gliomas involved are more focal as opposed to these big wide exposures for epilepsy or something like that. And we went through all of these issues here in terms of the use of the ice wringer solution. The only other thing I'll say is although we started off with a margin of one centimeter, actually you heard George say yesterday it was two centimeters when that article came out in 89. I then wrote an article in the New England Journal. I said it was the one centimeter rule, but as I've seen the field evolve and I've been convinced from Hugh's experience, I now believe you can do a resection up to one of those numbers, not violating the number, but up to one of those numbers without a loss of function. So I don't stay more than a centimeter away. The other thing is you gotta be flexible. So in 42% of the time when I went into the operating room, before I made a skin incision, I didn't like the way the patient was behaving on these drugs and I switched it around. If I don't like propofol, I'll go to dex, I'll change the Remy, and if worse comes to worse, I'll just leave them awake and just get it done. And as far as stimulation induced seizures with my technique at my currents of two to four milliamps, the likelihood of a seizure in my experience is 2.7%. And as far as the complications are concerned, look, you gotta have a stomach for this procedure. You can't be intimidated by it. You're gonna get deficits. There are gonna be a lot of early deficits. In fact, this was also a study that Eddie and our group published. The lines are not important, but in every graph looking at post-operative function, whether it's comprehension or naming, in a month, all these patients look terrible in the beginning. They all get worse and then in a month, virtually all of these patients get better and then you define the permanent deficits from two and three months out from that point. But you gotta be prepared for that. As far as the plasticity issue, again, learning from Hugh's work over the years, it definitely exists. This is a perfect example of a patient, you know, preoperatively you would look at this and say, okay, I don't wanna operate on this. It's right in the middle of the motor cortex. You see the red is the DTI tract. I found one site that I could actually get in through the cortex that was silent. That's what you do to get this lesion out. And because you're mapping the patient, you're gonna push it. So this patient didn't look very good at the end of surgery and they were really having trouble afterwards. But the mapping was preserved at the end of the procedure. So therefore, I knew it was gonna come back and sure enough, three months it was back completely. So don't get nervous about how these patients look post-operatively. The data on the plasticity, just in my experience, this is a study that's about to be published in JNS, which shows in my experience, again, like George, I'm old enough now with gliomas that I've had to go back and reoperate on my patients. And when I've taken the first map and I've reoperated and taken the second map, you can see in the top two panels, the difference in time for the reoperation is 32 months. Then I go back and look at the intraoperative image and then we look at the function that we see. The bottom line is I don't see gain of function very often, but there's loss of function in these remapped patients in up to 40% of the case. So now the philosophy should be if you go in and do a case, if you map function, if tumor's right there and it's functional, leave it alone and then come back several years later and in 40% of the cases, the function's gonna move. I don't know what the timeframe for that is, but certainly I've seen it as little as a year and a half after that first surgery. Okay, so here's the animation. Let's see, how much time do we have there, see? No, not much, okay. So let's just skip over this and let me just finish this. I'm just gonna show you the final setup because I'm pretty much done. So this is what it looks like and I just wanna just take you through this and show you what the mapping does. So this is a setup. This is how I use the corticography. This is how I stimulate, looking for after discharge potentials. And then, okay. So I'm stimulating before she sees the picture, typically. So I've deactivated the cortex, but she's still naming now. I stimulate, but she can't name the object. And that's basically it. So I'll stop there, but I think this is the basic strategy for the naming, the reading, any of the function. You basically have to stimulate before they see the visual cue. If they can name it, then you know that's not an essential site. If they can't, that's essential and you have to leave that there. Okay, so I'll stop at that point. Thank you very much. Thank you.

neurosurgery

asleep-awake mapping

motor mapping

bipolar electrode technique

awake mapping

plasticity