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Endoscopic Skull Base Surgery: Lessons Learned

Ted Schwartz

September 16, 2020


- Good evening, ladies and gentlemen, and thank you for joining us for another session of the Virtual Operating Room from The Neurosurgical Atlas. My name's Aaron Cohen. Our guest today is Doctor Ted Schwartz from Cornell University. He is truly a pioneer in minimally invasive and endoscopic skull-base surgery. A dear friend of mine, technically a superb and a master surgeon. And tonight, he's gonna talk to us about the lessons in 20 years of his journey in endoscopic skull-base surgery. Ted, it's an honor, and we're very much looking forward to your talk.

- Aaron, thank you so much for having me. As we go back a long way, and we've been friends for a long time. Even though I did beat you in foosball that one time, you're still friends with me, and I appreciate, or maybe you beat me, I don't remember.

- I beat you, but that's okay.

- All right, fair enough. Anyway, it's a pleasure to talk tonight about some of the lessons I've learned doing endoscopic skull-base surgery and minimally invasive surgery, 'cause when I started working in this field, so much less was known than is known now about how to do these procedures safely. And I kinda wanted to go over some of the lessons and set them out, very specifically talk about certain ideas that I think about when I do cases. So, let's go to the first slide and start the presentation, if we could. Great, so, you know I'm at Cornell and I've been here for the last 20 years and really built this whole program at Cornell, and obviously, it's an institution that's close to my heart. So, the way I wanted to set this up was kinda think about in my head, "What do I do differently now than I did 10 years ago? And what's the key piece of information that I'm thinking about when I start a particular case? Why do I make the decisions I make? What did I learn from my prior mistakes that made me change what I do to do something new? So, lesson one for me was find a great rhinologist, and that was a collaborator in Vijay Anand who really helped me think about the nasal corridors as a passageway to the brain. We did all our cases together for years, and still do, and I learned a tremendous amount from him. And I think it's very important, as a neurosurgeon, if you wanna do endonasal surgery, to have someone you can work with closely, who you trust, you rely on, and is really a partner. The other quick thing is we do our cases with a scope holder, and that that's a little unusual. Most people use someone else that holds the scope. And we do just as sophisticated cases as everyone else, as you know, and we put it on a scope holder, and you become very facile at moving that around very quickly. And the truth is, I like having it stable, I like having my eye fixed in space. I don't want someone else controlling where my eyeball is gonna be and having to worry about where they think I should be looking, as opposed to where I wanna be looking. So, it's part of the theme of there's more than one way to skin a cat, there's more than one way to do these cases, find something that works for you, and if it works, stick with it. So, what are our goals of skull-base surgery? And this is not just minimally invasive, but any skull-base surgery, is to recover any neurologic deficits. You wanna decompress the tumor, decompress any nerves that are compressed, but maintain or improve quality of life. We don't wanna hurt our patients, so we make certain decisions about taking out tumors where it's that last bit of tumor that we take out that sometimes causes the neurologic deficit that we regret. And we have to ask ourselves, "Was that the right thing to do?" Ensure that the tumor and the symptoms do not come back for as long as possible, ideally forever, of course, and to do no harm. And that doesn't always involve achieving a gross total resection of your tumor. So, skulls-base surgeons kinda like to beat their chests and show a post-op MRI showing that they got out the whole tumor, but what's more important often than getting out the whole tumor is keeping the patient functioning at a high level, and getting out as much tumor as you can safely get out, of course. So, GTR is not always the goal, but it is often the goal. And it's as often the goal in minimally invasive endoscopic surgery, as it is in open surgery. We're not compromising our outcomes because we're doing endoscopic surgery, but in all our surgery, we're balancing extended resection with quality of life. And that's something that takes years to really learn. It's really that when-to-stop question, when do I leave tumor behind? When do the risks of a gross total resection outweigh our benefits? And when do we know that radiosurgery probably is the way that you're gonna treat a lot of this tumor that's invading, not only the cavernous sinus, but also extending down through Meckel's cave? And so, this is a case where we know we're gonna leave tumor behind, so, then we think, "What is it that we need to decompress? What is it we need to prepare this patient for, for their radiosurgery?" So, I'm gonna talk about some different pathologies and some key lessons that I learned over the years that helped me take out these tumors. So, for pituitary adenomas, non-hormone-producing ones is really what I'm gonna talk about here. The goal is maximal cytoreduction with preservation of pituitary function. So, you wanna get as much tumor as you can, but you wanna make sure the pituitary functions as well as possible, and the way to achieve that is to find the pseudocapsule. So, in all of these cases, I'm internally decompressing the tumor first, even if it's a large tumor, and I'm looking for that pseudocapsule, and I'll show you a video of that. And then with cavernous sinus, I did just a case today, tumor invading the cavernous sinus, if it's soft and suckable, you take out as much as you can. But obviously, if you're gonna lateral to the carotid and put the cranial nerves at risk, in other words, not just going behind the carotid, you really wanna have a compelling reason to do that, 'cause if you leave a little tumor there then that's okay, they grow back very slowly, I'll talk about that, and they can be treated with radiosurgery. You don't wanna cause a cranial neuropathy in a patient. But some of these soft tumors, you really can be aggressive in the cavernous sinus. But if it's firm, it's okay to leave some tumor in the cavernous sinus to avoid a cranial neuropathy. And the residual is easily treated with SRS. So, Luke, let's go to this video. This is just a very straightforward, simple macroadenoma. We've opened up the floor of the sellar, and I do it very widely, from medial cavernous sinus, medial cavernous sinus, all the way to the superior inner cavernous sinus, dissect the dura off the tumor and off the, yeah, and then come around the top, dissect the dura off the tumor, the periosteum. So, in a big tumor like this, I'll internally decompress it first, send your pathology, and then I try to find that pseudocapsule. So, you can see here, I'm working my way around the tumor, you see the normal pituitary gland, it's very thin, but you can find that pseudocapsule, even in giant tumors like this. And I just keep working the pseudocapsule until I get the whole thing out. And that's how you ensure the pituitary gland's gonna work afterwards, and that you've gotten a gross total resection. Put a little bit of gel foam to stop the bleeding over the cavernous sinus. I use Surgicel Floseal, and here we harvested a nasoseptal flap 'cause I thought there'd be a big CSF leak. And we closed with that. I don't reconstruct the floor, and a little bit of glue. Can we go to the next slide? Actually, I'll go to the next slide. Okay, so what did we learn? Well, so we looked at our cases, and we only looked at cases that are greater than five years follow-ups. We're looking at long-term outcome after endonasal resection of non-functioning pituitary macro numbers. What we found was that recurrence after gross total resection on the left was extremely low, 10 years out, and progression after subtotal resection also was not that high, right, only about 25% of our patients progressed. And if you look at the number of the patients that required treatment, in other words, not just that they progressed, but they required treatment, it was lower, and very, very low. So, for gross total resection, and I'll show you the numbers when we go to the next slide, but the key point is even for subtotal resection, not all these patients needed additional treatment. So, a lot of these patients never got radiation. So, how do we manage patients with the subtotal resection after surgery? What's the rate of recurrence? Should we irradiate postop residual? So, the rate of recurrence, as we saw, is very low, five and 10-year recurrence after gross total resection was 4%, roughly. But the probability of requiring any kinda treatment, so, sometimes you see a little tumor, you don't have to treat it, was basically 1% at 10 years, so, that's really low. So, we try to get a gross total resection. If you get a subtotal resection, and we did early radiation in just a handful of patients, we mostly follow these patients. So, we have 57 patients, subtotal resection followed, what are the chances that the disease is gonna progress at five and 10 years? It's really only about 25% and their need for treatment is only 20%. So, should everyone with residual tumor get post-op SRS after a non-functioning adenoma? The answer is no 'cause only 25% will progress, you might as well follow them, and if they progress, you can treat them. Now, there are some predictors of progression, tumor in the cavernous sinus, tumor with a high Ki-67, tumor that's greater than a centimeter cubed, revision cases are more likely to progress. So, those you may wanna think about doing upfront SRS. If you have a big tumor in the cavernous sinus greater than a centimeter, high Ki-67, you can radiate that one. How important is intraoperative MRI? We did a meta analysis of the literature. My gut was that it really, it doesn't make such a big difference if you use the endoscope. And so, if you look at the rate of gross total resection for endonasal surgery by itself, it was about 70%, if you look at microscopic plus intraoperative MRI, it's about 70%, and endoscopic plus intraoperative MRI is 70%. So, it looked like the endoscope, if you use the endoscope and you're very facile with the endoscope, you do about the same as you do with intraoperative MRI when you look at the rate of gross total resection. The papers that are written will say, "Oh, we went back and looked and found tumor," but they may have aborted their surgery early because they knew they were doing an intraoperative MRI, and so, they could say, "well, I'm not sure what that is." whereas if you had an endoscope, you might've been more aggressive upfront. What about re-operation? How well does that work? Well, we looked at our patients with re-operations. This was another lesson that we learned, that re-operation is actually very effective. Gross total resection was achieved in about 60% of patients, but GTR, or near total resection, was achieved in 93%, and your total being greater than 95% resection. So, we get most of the tumor out in most of the patients. And, of course, it's lower in patients who have a cavernous sinus invasion, CSF leak was not that much higher, it was 2.4%, which is still pretty low, visual fields improved in 53%, and endocrine remission was achieved in about 75% of our patients who had endocrine-producing tumors. So, don't be shy to do a re-operation if you think you can do a good job, not all those patients need to get radiation. So, the big complications I'm thinking about when I do it a pituitary adenoma, are postop hematoma and CSF leaks. So, how do I avoid them? Well, I try to remove all the tumor, that helps avoid a postop hematoma, and I spend extra time ensuring hemostasis. So, I irrigate for a long time, I do a little bit of gel foam, but mostly Surgicel 'cause it doesn't expand a lot of irrigation, and if I think I'm gonna get a big leak, I'll harvest nasoseptal flap, and if I think I'm really gonna get a big leak, I'll put a lumbar drain in, and I'll talk about lumbar drains because they do make a difference. So, we did a study, and this is a lesson learned, about who gets post-op hematomas after endonasal surgery. And we found that it occurred in about 1.5 of our patients needed a re-operation for a postop hematoma, and their vision would get worse. Clot evacuation improves vision about 90% of the time, but if they have a postop hematoma, or their rate of endocrine dysfunction is also very high, about 80%. So, that's one thing that often gets lost if you have a cellar hematoma. And what predicts a cellar hematoma? Well, the size of the tumor, big tumors, suprasellar extension, cavernous sinus extension. So, the incidents of hematoma in tumors greater than three-centimeter diameter was 5%, which is actually pretty high. So, it's those big macroadenomas that you have to really be careful and make sure you get good hemostasis. What are the limits of the internasal surgery? Well, it's that carotid artery, it's going lateral to the carotid bifurcation. And sure enough, here's a tumor, it's everywhere, it's in the clivus, it's suprasellar, it's anterior. But the only part that we left behind was that part lateral to the carotid where we just didn't feel comfortable and had a tough time seeing over there. So, that's a good lesson to know. So, what about craniopharyngiomas? Let's talk about some lessons from craniopharyngiomas. First of all, quality of life is critically important. Hypothalamic injury at a young age is devastating, so, try to avoid that. Panhypopituitarism, however, can be managed with medication. So, I try to get a gross total resection and cure patients with craniopharyngiomas, even if it means taking the stock because I can give them medication. The other thing is, recurrent craniopharyngiomas that have been radiated are extremely difficult to manage and often require multiple operations. It's very much harder to get it out after they've been radiated, and I'll show you data on that. So, rather than take a patient and leave tumor behind and hope that radiation will control it, I'll try and get it all out, if there's tumor left behind and it starts to grow back, and I think I can get a gross total resection, I'll do a re-operation before I do radiation. I'll only do radiation if I do not think I can get a gross total resection with surgery. So, the lessons are, the advantage of endonasal surgery for craniopharyngiomas is mainly vision. Endonasal surgery has a higher rate of visual preservation than a craniotomy, and less brain retraction. You're still going for gross total resection, it's the goal of surgery, even if it means sacrificing the stock. Radiation reserved only for cases where re-operation has a low likelihood of achieving a cure. So, here's an example of a craniopharyngioma. Coming in from above, you have the disadvantages of working around the neurovascular structures, and I'll show you a video taking out that intraventricular tumor from below. We're gonna open the dura here, we have a suprasellar exposure just above the, I'm gonna draw some pictures. So, here we're coring out the center of the tumor, and what you're gonna see, then we're gonna work our way around the outside of the tumor. The gland is below, it's down here, we're mobilizing the tumor in. You can see the PCA, we're working on the bottom of the stock, sorry, the bottom of the chiasm is right there. Here's the stock. We try to save the stock. So, we're gonna sharply dissect the tumor off the stock. You see us doing that here. And then we work the plane with the third ventricle, and you see that beautifully from below, the plane of the third ventricle. You see the third nerve here, the PCA, all clear of tumor, here's the carotid, and we got a gross total resection of the tumor. Let's go to the next slide. And what you can see here, I'm just gonna draw for a second, is the stock here. Let me make make this red so it's easier to see. You can see the nasoseptal flap here. This is the gasket. We use a gasket seal, a little fascia lata around it. You can see the chiasm here, the AComs here, tumor's gone. Again, this is the stock floating in the breeze right there. So, the advantage of the endonasal approach, you can see there's no flair signal in the brain postoperatively, we didn't do any retraction of the brain. Here's an example of a craniopharyngioma that was resected twice with a craniotomy and radiated because it recurred. And where did it recur? It recurred it in the medial optic canal. You can see it right here, but you also see this extensive encephalomalacia in the brain from surgery. Here again is the tumor in the medial optic canal and all the encephalomalacia from two prior surgeries. So, we were able to upload this one. This was one of the later ones. So, we're trying to expose the medial optic canal, and the medial optic canal is very easy to expose with an endonasal surgery. That's something that I had to learn over time. I was scared of the medial optic canal, it's hard to get to through a craniotomy because you're working past the optic nerve, but you see here, we can open up that medial optic canal and that's where the tumor is. And then we're gonna open up the optic sheath and then we're gonna roll the tumor out of the optic canal. Here, we're opening up over the sellar and then we're gonna start going laterally. So, right here we're going out to the lateral optic sheath. We're opening up below the superior cavernous sinus to get out the tumor that's in the suprasellar cistern. There's the gland below us. Let me draw a picture here. Gland is down here. We're opening up the superior inner cavernous. And here we're opening up the medial optic canal. And you'll see, we're gonna find the lateral margin of the tumor and just roll it out of the optic canal. And the ophthalmic artery is gonna be below, it's down here. And the nerve is very pale up here, you can see the nerve. So, we're gonna sharply dissect it off the optic nerve from below. You see that beautiful view. All right, we can go to the next slide. So, here's postop and you see that the optic nerve has really expanded within the canal. So, what do we know about craniopharyngiomas? Well, we did a review of the literature. We compared 2012 data to more recent 2017 data, and gross total resection rates in 2012 were about the same as craniotomy, CSF leak rate was higher, but if you go to the 2017 data, the gross total resection rates were starting to go up as high as the highest craniotomy rates. CSF leak rates were in some centers going down as low as craniotomy. But this is what's really important, the visual improvement rates were higher than craniotomy visual improvement rates, and that's really the main advantage of the endonasal approach, is that you have better visual improvement rates. So, we also did a study in our center where we basically looked at all the craniopharyngiomas we'd taken out of the last 20 years and we put them all on slides, and we sent those slides to experts. And we asked them to say how many of these cases could be equally well taken out with a craniotomy or endonasal surgery? And we found 21 that had done endonasally and five that would have done transcranially by some of my partners who took them out through a craniotomy, and because they weren't doing endonasal surgery at the time. So, we compared the results. So, these are tumors that are the same size, okay? An extent of resection, you can see it's circled here, was about the same. Gross total resection rates were higher for endonasal, increase in flair volume was much higher for craniotomy, craniotomy needed more ah-gee-ment radiation and recurred more frequently, and if you look at vision, visual improvement was much higher with endonasal than it was with transcranial. The other thing was complications. Cognitive death was at very high for transcranial, obviously, CSF leak was a little higher for endonasal, and we actually had some strokes as well, but overall the complications were actually higher with transcranial than they were with endonasal. So, what about re-operations for craniopharyngiomas? I had said to you that I prefer re-operation to radiation if I can get the whole tumor out. So, we looked at our re-operations, and what we found that rates of gross total resection for re-operations, we compared 35 re-operations to 22, sorry, 22 re-operations to 35 first operations, gross total resection was about the same, and visual improvement was about the same. We got more anterior pituitary deficits in the first operation because a lot of those patients were already hyperopic and we got more DI in re-operations compared to first-time operations, probably 'cause the tumors were just much more scarred in. So, they did very well. Another paper that we wrote, we looked at 24 re-operations and we divided those into those that had prior surgery and those that had prior surgery plus radiation, and that was Group B. And we found that Group B had a much lower gross total resection rate than Group A, and Group B had a lower KPS than Group A. So, the one our patients that did better and had higher gross total resection rates were re-operations that never had radiation before. They had radiation before, that was really a negative indicator for how successful they were gonna be. And then we also looked at this question of, "Do we preserve or sacrifice the stock?" And what does it mean if you say to a patient, "I'm gonna leave your stock behind you with subtotal resection to save your pituitary function." Are we successful if we do that? So, we looked at our patients, divided them into gross total resection, in those in which we did a subtotal resection, and even in the ones where we did a subtotal resection, we had intrapituitary insufficiency 78%, DI 67%, high progression, high radiation rates. So, these are the subtotal resections. If we did a gross total resection and we took the stock, obviously, they all had intrapituitary insufficiency, most of them went into DI, but they did really well, they had very few recurrences. Now, in some of the patients, we did a gross total resection and we were able to preserve the stock. We tried to observe and we did preserve it to try to save their pituitary function. So, were we successful? Well, the answer is yes, we were successful a third of the time in preserving anterior pituitary function, and half the time, they did not go into DI. So, that's valuable if you can keep them out of DI and keep them out of anterior pituitary insufficiency but only if the tumor doesn't recur. So, the recurrence rate was slightly higher and we radiated those patients. So, this is really the goal. If you can preserve the stock and take the whole tumor out, that's the goal, that's the best outcome, but if you can't, then you should sacrifice the stock 'cause if you do this, they're all gonna need radiation, many of them are gonna recur, and they're still gonna be hypopit as we showed in our cases. So, that's where our philosophy comes from. Now, meningiomas, what have I learned about meningiomas? Well, we all know about the Simpson grading system. And I recently wrote an article that's gonna be published soon about why we should abandon the Simpson grade. And I'm gonna go through a whole list of reasons, but the bottom line is the Simpson grade is very subjective. The surgeon looks in the operating room and tells you what they took out or not, and there's a whole host of papers saying that we're really bad at doing that. And the other thing about the Simpson grade is that it doesn't really correlate with recurrence in terms of these different grades, one, two, and three, and there's a lot of other reasons. So, I'll get into the Simpson grade in a second, but the lesson about meningiomas, the advantage of endonasal surgery is visual preservation. That's where endonasal does a little better. The gross total resection rates are about the same. Case selection is the key to success. Not every tumor is a good candidate for endonasal surgery. And if you choose the wrong cases, you're gonna have bad outcomes, and you have to acquire the appropriate technical expertise, these are difficult cases, they're challenging. I mean, if you have the adequate experience, you can do them, but you can't assume that you do just because you can do open surgery. And the Simpson grade is not applicable to endonasal surgery, okay? You can't talk about a Simpson grade, and one of the reasons is when you do endonasal surgery, you're working through a small hole, you can't see at a 90-degree angle to tell what Simpson grade you got. The truth is, we don't really know, we can only see what we can see. But the same is true with craniotomy, if you do craniotomy for convexity meningioma, you can't see if there's tumor left behind around the margin of your craniotomy. And that's the problem with the Simpson grade, it's very subjective. So, the intraoperative inspection for residual dural tail can never be performed after endonasal surgery due to a limited bone opening and our inability to adequately see 360-degree rotation at a 90-degree angle. So, we can never really give an appropriate Simpson grade. However, even a craniotomy does not permit visualization of the undersurface of the bone. So, it's very hard to give an adequate Simpson grade and it's subjective. So, ultimately, it's archaic and it should be abandoned. The goal of meningioma surgery is maximal resection of tumor with minimal morbidity, that should always be the goal. Here are the reasons why the Simpson grade should be abandoned, okay? I'm gonna go through them very quickly. Intraoperative assessment of extended resection, coagulation of dura, removal of hypersonic bone are completely subjective and they don't correlate with postoperative imaging. So, we have post-op imaging, that should be used to tell what we got out, it's not in the Simpson grade. There's a wide range of occurrence, report after Grade I removal of the Simpson grade, okay, it's very variable. There's minimal difference between Grade I, II, and III, when you do a microscopic surgery. Most of the papers on the Simpson grade, it's not assigned prospectively, but it's done retrospectively from review of op notes, which is gonna be totally inaccurate. Post-op MRI scans are not used to confirm standard resection in all of the Simpson grade papers. So, they may be completely wrong in what they're saying they left behind. Limited bone opening prevents inability to inspect. The radiographic dural tail is not always tumors, sometimes it is, sometimes it isn't, we don't really know. Hyperostosis is sometimes tumor, sometimes it is sometimes it isn't, other papers showing that. There's no data on the regrowth potential of hypostatic bone and dural remnants. We don't really know if you just leave hyperostotic bone just at the same rate of regrowth as tumor, we don't know. There's no data correlating the volume of residual tumor with a recurrence rate. Recently, there was a paper written on that and there is starting to be data on that showing that the volume is important, so, not all Grade IVs are the same, but you can leave a little tumor, you can leave a lot of tumor, and that's gonna make a big difference. And also, the Simpson grade ignores the fact that we can use postop radiation to control tumor growth. And so, leaving a little behind and radiating it, it never goes back, it's the same as getting a Simpson Grade I, might as well be the same. We also know that tumors in different locations have different genetic growth potentials and the genetics of the tumor are incredibly important, and that's completely ignored in the Simpson grade. It doesn't apply universally to meningiomas in all locations. So, I'm gonna move on from there 'cause I'm sort of beating a dead horse, but these are some papers showing that recurrence rate after Simpson Grade I, II, and III, is basically the same. So, how do we take out the tumors endonasally? I wrote this paper with Doctor Cohen. You have to make sure you have an adequate bone opening, right, 'cause the tumors can extend pretty far laterally and you wanna get as much of that dural tail as possible. So, you do a much bigger bone opening than you would with a craniopharyngioma. I'd like to come over the top of the tumor first, that's the lesson, because the danger zones are laterally. Superiorly, you often can come over, it's just gyrus rectus there, you come over and you wanna find the ACom the A2, 'cause those are the vessels that you need to dissect off the back of the tumor. So, you have to find those and dissect them off. You're gonna anteriorly decompress your tumor and then you're gonna come around the bottom and find your stock, and dissect the stock, and you have to address the diaphragma sellae. And this is just a picture of dissecting that diaphragma sellae. You can see the pituitary gland below here. And then you have to open up your optic canals. And when you open up the ophthalmic canals, you can take the tumor out bilaterally. And here's an example of a tumor removed. You see both medial optic canals are completely opened up. You can see chiasm, this is stocks here, this is gland, this is lamina terminalis, A1, ACom these are your A2s, this is A1 on the other side. This is your olfactory nerve, gyrus rectus, gyrus, rectus. These are the optic canals completely open and free of tumor. I just wanna emphasize that when you open up the optic canal, the ophthalmic artery runs inferior. So, when you're opening it up, open it up up here, 'cause you don't wanna slice into the ophthalmic artery, that is bad form. Often, the optic nerve is compressed against the A1 and it's paper thin, and manipulating that optic nerve is why you get visual loss from above. So, we try not to manipulate that optic nerve. So, here's a case that looks like it's encasing A2, but really it's not, but it looks like it is. You might say, "Oh, you shouldn't do that endonasally." It's invading both medial optic canals, for sure. Sorry, let me just show you that. Here you can see the A1s are going over the top of the tumor, but the tumor lies between the carotids. So, it's actually pretty good. Here's the A2s above. So, we should be able to get this whole thing out. Here's tumor in the medial optic canals again. All right, so, let's show this video, Video 55. Luke, you're on. So, we harvest the vascularized nasoseptal flap. We drill out all this septation taking the mucosa down, open up the bone widely because we have to get all of the attachment of the tumor out. We open up the top of the tumor, we internally decompress it, send our pathology, and then we work our way over the top and we find those A2s and A1s, there they are. So, remember it looked like the A2 was encased to the tumor, here we're gonna cauterize it and sharply dissect a Huebner A2, and then A1 off the tumor, little more internal decompression, then sharp dissection. And we're gonna open up the medial optic canal on one side and roll the tumor out. There's the optic nerve here. And then we're rolling the tumor off the optic nerve. If you notice, we're rolling the tumor off the nerve, we're not touching the nerve. We open up the optic canal on the other side and roll the tumor off the nerve. Here it's very stuck to the nerves, so, we're gonna sharply dissect it. And you see what a great view you get of that plane of dissection. Here's the pituitary gland. We're opening up the superior cavernous sinus, cauterize it, cut it, and then we're gonna dissect the bottom of the tumor off the stock. And here's that picture. So, the tumor is all out. You can see A1, A2, you can see A1, A1. And then we do a gasket seal in this case. Here we use fah-she-lada you can also use AlloDerm, AlloMax. We wedge in a piece of bone for a buttress and then cover it with a nasoseptal flap. and then cover that with some glue, either Duraseal, or Adherus, whatever you like. All right, let's go back to the slides. So, here's post-op, you can see there's the rigid buttress, stock, gland, nasoseptal flap. Here you see the A2 in the breeze, optic nerve here, optic nerve there. And this case is not a good case for endonasal surgery, but the reason is not on the sagittal, the reason is here. These are the optic nerves. You can see there's a dural tail that goes lateral to the optic nerve. So, that is gonna be challenging for us to take out endonasally. And here you see the tumor is around the optic nerve, these are the optic nerves. There's tumor lateral to the optic nerves encasing the optic nerves on either side. That cannot be taken out safely endonasally, so, I did a craniotomy. Just showing you again, the optic nerves are encased in the tumor. That's different than the A2 encased because probably the vascular supply of the optic nerve is in there, it's been very hard to see past the optic nerve. So, this is the last time we looked at our meningiomas, we'd done 61 of them. The early group, before 2008, we didn't quite know what we were doing, we didn't know how to close that well, we weren't using a nasoseptal flap. And if you look at the results, our gross total resection rates initially were not that high, 62%, they went up to 92%, versus 84% if you review the literature on craniotomy, and visual improvement was 83% for endonasal surgery versus 57 for craniotomy. CSF leak rate went from 25% down to 6%. And two of our patients were obese patients where we couldn't get a lumbar drain in, and we just did a cutdown, put in a lumbar drain, and they stopped. So, if you look at the patients that ultimately have lumbar drains, the CSF leak rate is lower, maybe 1% or so. So, if you compare the literature, sorry, these don't line up, of transcranial surgery versus endonasal surgery, this is the number here, 75% versus 87% was in 2012. CSF leak was too high, 21%, visual improvement was okay. But then if you go to 2017 data, your gross total resection rate goes up higher and it really it's just about the same if you're good at a craniotomy, CSF leak rate at some centers was 0%, so, you can't get it down lower, but here's the real advantage, is visual improvement rates, which on the whole are higher than the visual improvement rates through craniotomy. So, that's the summary for endonasal surgery. Now, we did a similar study for meningiomas as we did in craniopharyngiomas, which is to compare apples with apples and not oranges with oranges, because you need to compare. You don't look at craniotomy versus endonasal surgery, you have to look at the same-sized tumors, not giant tumors that were taken out with a craniotomy that you would never take out endonasally, but small tumors, right, the easier ones where you're gonna get better outcomes regardless of how you take them out, 'cause those are the ones that are appropriate for endonasal surgery. So, we looked at our center and looked at cases that had been done either through a craniotomy or endonasally, we sent axial sagittal coronal images of all cases that were done to three experts and said, "Tell us the ones that could be done equally well through either approach. And if you can't take it out endonasally, we're not gonna look at it regardless of how it was done." So, this is an example of an endonasal case on the left, endonasal case here, and this is a transcranial case here, this is a transcranial case. These are cranial here, these are endonasal here and here. And so, you can see they're similar-sized tumors. And we had 18 endonasal, 15 transcranial, preoperative tumor size was about the same, preoperative flair signal was about the same, no significant difference. Gross total resection rate for endonasal was 82%, for transcranial it was only 53%, and that was not statistically significant, but it was a trend. But extended resection, also slightly higher for endonasal than transcranial, but again, not statistically significant. So, it's not about getting out the tumor. But if you look at the flair signal in the brain from doing a craniotomy and the DWI signal in the brain indicating contusion, it's significantly higher for transcranial than it is for endonasal, okay? So, that is an advantage of endonasal surgery, you're not retracting the brain. And if you look at visual improvement, it's higher with endonasal than transcranial, although it was not statistically significant, it was close. But if you look at visual deterioration, it was 38% for transcranial, 0% for endonasal. So, that's really the main difference. This is where endonasal seems to make a difference, vision, and vision is the most important thing for planum tuberculum meningiomas 'cause that's why we're taking out the tumors, we're trying to preserve vision. So, that has to be your primary goal. It's doing your complications are higher. And then there will be complications in our group with craniotomy versus endonasal, but on the whole, that's probably not true. The other thing that we looked at was this question of a cortical cuff. I talked a little about it. Brain edema, is that a contra-indication? The answer is no, you don't have to have a cortical cuff between your tumor. There's always blood vessels, A1, A2, A, always dragged it over the top of your plane with your work on meningiomas, and you can dissect those off as I showed you. That is not a contraindication. If you know what you're doing, the contraindication, it's really about case selection and the contraindication is tumor lateral to the optic canal. So, we have a paper that's coming out soon showing that, where we have a grading scale, and if the tumor is lateral to the optic nerves, you're not gonna get the whole tumor out. Here's another lesson, olfactory groove meningiomas. I did spend a little while trying to take them out through the nose. I don't think any of them should be taken out through the nose, and I'll tell you why. So, if you look at the results of craniotomy, first of all, for olfactory groove meningiomas, what's interesting with big bifrontal craniotomies is that there's a fair amount of bleeding, 10%, brain swelling, 14%, death is 3.5%. This is where they look at the complications. They're not insignificant for olfactory groove meningiomas and this is for doing a craniotomy, but they don't even consider anosmia a complication, they don't even look at it. And if you look at endonasal surgery for olfactory groove meningiomas, and this is the largest series, and these are very good surgeons, right, these are some of the top endonasal surgeons in the country, the length of surgery was nine hours, length of stay was 11 days, 36% of the time they'd do a re-operation to remove more tumor, CSF leak rate was greater than 30%. So, if you do a craniotomy, and of course, 100% of those patients get anosmia, if you do it endonasally, 100% of your patients are anosmic, you do a craniotomy and the tumor is less than four centimeters. First of all, who has pre-op anosmia? 4.5% had pre-op anosmia. Postoperative anosmia, sorry, this is endonasal surgery, sorry, I'm a little confused, postoperative anosmia is 100%. But for tumors less than four centimeters in that paper, only 4.5% had preop anosmia. So, they gave an anosmia to every single patient, and these patients, you could have preserved their sense of smell. And our goal of surgery is preservation of function. And this is the complication rates after endonasal surgery, as I mentioned to you, 30% CSF leak rate, but also respiratory failure, hydrocephalus, brain abscess, new seizures. These are not totally benign procedures. And the CSF leak rates did not go down that much, even after they started doing a nasoseptal flap. So, when you ask me which of these cases should be done endonasally, some people might say, "Oh, this one is small." I would say, "No, 'cause this one has a sense of smell, and if you do an endonasally, they're gonna lose it." And this one is too big to get the whole thing out endonasally. So, neither of these are good candidates for endonasal surgery. Preservation of olfaction is very important, endonasal surgery, you do at 0% of the time, if you do a craniotomy, you can preserve it 55% of the time, and if they have preop olfaction, you can preserve it 85% of the time. And if the tumor is less than four centimeters, you can preserve it 80% of the time. But if they have olfaction impaired and the tumor is greater than four centimeters, you're only gonna preserve it less than half of the time. But that's why I think you should do it from above. And if you look at the data, endonasal versus transcranial surgery, gross total resection rates are lower for endonasal than transcranial, and that's true even in 2017. CSF leak rates are too high and they never really came down. Visual improvement is a little bit better, but that's really not the goal of doing olfactory groove meningiomas, the goal is really to preserve their sense of smell, it's one of their main goals. And for endonasal, you can't do it, but for transcranial, you can do it 50% of the time. So, that was my lesson learned. I don't take these out endonasally anymore. And I like to do them through a minimally invasive eyebrow incision. The only issue, and I'll show you this, what you see in blue here is what you can see with an eyebrow incision and a microscope. In orange is what you can't see because the roof of the orbit blocks your view of the cribriform plate and the sphenoid ring blocks your view here, and the plane and blocks your view here, okay? So, if you're gonna do an olfactory meningioma through an eyebrow incision, you absolutely have to bring in the endoscope at the end and use the endoscope to see up here and to see here. You're not gonna be able to see that with a microscope. This just shows you what that looks like. Here's the view, here's the view from above showing you you can't see the cribriform plate with a microscope, you can't see sphenoid wing, you can't really see the bottom of the sellar either. I did a couple cases, eyebrow versus endonasal, and my endonasal results were not good at all. I had 50% gross total resection rate versus 100, anosmia, obviously 100%, versus about half, complications were higher here. So, I abandoned endonasal. Now, this is a woman, she gave me permission to use her picture, she had an eyebrow incision to take out a olfactory meningioma, and you really can't see it, right, you can't see it. By the way, it's this eye, just you know there is a very tiny little scar there, but you can just barely see it. So, the results are quite good. This woman also gave me permission. She had her surgery through this eyebrow. This is the kinda cosmetic result you can get, but you make it in the eyebrow, not above the eyebrow, right in the eyebrow. So, here's an olfactory meningioma, pretty big, I would say too big for endonasal surgery. Let's show this video. So, I'll show you how we're drilling off the top of the orbit, which is important so you can see. We'll open the jar eyelid to remove the orbital rim personally, internally decompress the tumor, take the tumor away, peel it away from the frontal lobe. Usually, you see the contralateral olfactory nerve, it's hard to see the ipsilateral, so, you choose your side appropriately. So, it's very hard to see the base of the tumor here. So, what you're gonna see is we bring the endoscope in, we bend this element or eloquence thing, and we burn off the base of the tumor all the way down to the bone. You can even drill off some of the bone, but you don't wanna drill off the whole cribriform plate 'cause you'll go into the nose and they'll get a CSF leak. So, you cannot remove, let's go back to the slides, you can't remove tumor if it's in the cribriform plate. But here's the postop scan. So, this is the result. We wrote up our supraorbital keyhole craniotomy for olfactory groove meningiomas. And what you can see is 17 cases, tumor volume of 15 cubic centimeters, they're big, radiographic gross total resection, 94%, okay, pre-op flair, 9.8, post-op flair, again, 9%. So, really no change in flair signal in the brain, not significant. A little bit of DWI, 2.9 cubic centimeters. Length of stay, only three days, right? Remember the endonasal was 11 days, I think. Follow-up, 32 months, 11 patients had greater than two years follow-up. So, we had two recurrences and the recurrences were in the cribriform plate 'cause you can't take that out, but you can do SRS in the cribriform plate. And if there's a big tumor going into the ethmoids and down into the nose, you can do endonasal surgery. So, that's what we did in those two cases. But here's the really important thing, total post-op anosmia, the whole series was 30%, but one of them had it beforehand, new anosmia, only 20%. And again, it's that contralateral olfactory nerve that you're gonna be able to preserve, the ipsilateral one, very hard to preserve. So, you have to choose which one you're more likely to be able to preserve. Limitation, cannot drill out and repair infiltrated or hyperostotic bone, but you can treat that with stereotactic radiosurgery, and if extensive bone involvement and tumor in the nasal cavity, you can use a subfrontal approach, get a big pericranial flap, or just do an endonasal approach separately. Gamma knife works well for residual recurrent olfactory meningiomas, and the preservation rates of olfaction are very high. So, this here shows you tumor progression, only 5%, and this shows you deterioration in olfaction, and zero, very low, okay? Actually, some of them improved, most of them had no change. So, we wrote this article just sort of showing an algorithm of how we treat anterior skull-base meningiomas, some get endonasal surgery, some get eyebrows surgery, some get both, and that's something you can look at. So, lesson seven, I wanna talk a little bit about Meckel's cave and some new things that I learned. So, as we know, Meckel's cave schwannomas can either be in the nerve, which is distal, they can be in the ganglia, which is in Meckel's cave, or they can be in the root, which is proximal in the posterior fossa. And I found that the endonasal approach is great, sorry, for the root, so, the distal root, sorry, the nerves, and it's great, I wrote that wrong, so, I apologize, endonasal is good for the ganglia, okay, and the distal nerves, because that's distal, this is good for endonasal. But it's hard to get the root, it's hard to get the root, this was a mistake, in the posterior fossa. So, I learned from Doo-Sik Kong to do an eyelid approach. Transorbital is very good for Meckel's cave and very good for tumor going into the posterior fossa, and I'll share an example of that. So, we wrote a paper about endonasal surgery, and sure, if the tumor is here, you can see there's a corridor going into the tumor. And there should be a video, actually no, we're not ready for the video yet, but in order to get into Meckel's cave, you can see V2 is here, right? So, this is gonna be Meckel's cave, right here lateral to the carotid. So, this is what you wanna drill open if you're doing a endonasal schwannoma. So, post-op, I can just show you that we took out the whole tumor, but again, this is tumor is just in Meckel's cave, it's just in Meckel's cave, it's not in the posterior fossa, okay? Here's a case that's in Meckel's cave and the posterior fossa, right? And I did this endonasally, and lo and behold, I left tumor in the posterior fossa. I got it all Meckel's cave through the endonasal approach, and because you're coming this way, I'll show you that, it's hard to go this way and then make another turn this way because the carotid is in your way. You can get into the tumor, you can crawl to Meckel's cave, but it's hard to get to the posterior fossa. This is the approach that a lot of people do for these schwannomas, and it's great, except for the fact that you're attracting a lot of temporal lobe, right, there's a lot of temporal lobe here that you're attracting. And if you come endonasally, you're coming this way, and the issue is you can work through this corridor and you can get this tumor out, but you have to go this way, and then you've gotta make an angle turn this way. That's not so easy. But if you do an eye transorbital approach, it's a straight shot down the long axis of the tumor and you're attracting very little temporal lobe. So, I have loved this and have done it, and I'll show you a video of the approach. You're coming lateral to the orbit, you're drilling out the sphenoid bone and opening up the meningo-orbital band, retracting the temporal lobe. Now, I started doing this first with spheno-orbital meningiomas, particularly those that were hyperostotic. So, coming in this way, drilling out this bone, and you can see this is pre-op, make a little eyelid incision, and then draw out the hyperostotic bone. And then you can see post-op, here's all the hyperostotic bone has been removed, or I'll show you there. So, the eye falls back in and you get rid of your proptosis. Now, this is an interesting case. This is a dermoid. And when this woman came to me, 2013, it was in the cavernous sinus and it presented itself very well endonasally. You can see there's an area we can access it right here. So, I did an endonasal approach and opened up the tumor, and we drained it. And she did great, her diplopia resolved. The rim of the tumor, or the jeh-meh-roid was attached to her cranial nerves. I didn't think I could safely take that out, but we could drain it, get all the pressure off, and she did great for seven years. And then she came back with this seven years later, and now the tumor was no longer presenting itself in the sphenoid sinus, right? The corridor to get in was much less clear and less easy for me. So, she had diplopia again, so, we did a transorbital. Let's show this video. So, here we're drilling out the sphenoid bone. We're attracting the orbit, the orbit's over here. This is the sphenoid bone that we're drilling out. And we're gonna get to the dura of the temporal lobe and we're gonna remove the dura of the temporal lobe, and then we're gonna work our way to the superior orbital fissure and remove the bone all the way to the superior orbital fissure. And here, we're cutting the meningo-orbital band. So, this is temporal lobe dura, frontal lobe's above, this is the meningo-orbital band. And once we do that, we can retract the temporal lobe off the lateral wall of cavernous sinus and Meckel's cave. Cutting the meningo-orbital band a little more right here, see that? We're attracting the temporal lobe. The orbit is over here, and this is the tumor right here. So, we're gonna get into the tumor, decompress it, we're doing this with an endoscope. Here, I'm having someone hold the endoscope, it's not on our holder 'cause I need to move it and clear out as much of the jeh-meh-roid as we can. Although again, the cranial nerves were running along the margin of this and we didn't feel we could get it all out. I did a button closure. That's an inlay onlay of AlloMax with suture together in the middle, covered it with teh-seal. The eye falls back and you don't get a CSF leak. I learned that from, again, Doo-Sik Kong. We go back to the slides. So, this just shows you how much bone we removed. You can see that here. Just a little bit, you don't get exophthalmos or enophthalmos, there's enough of the bony canal that it holds the eye in place. Enough of the orbit is left. This shot just shows you post-op, her double vision completely resolved, and she did very well. So, this is a Meckel's cave schwannoma, like the other one, but here I decided to do a transorbital approach 'cause there's tumor in the posterior fossa. It doesn't really present itself that well to the sphenoid. And you can see, we can come in this way and retract very little at the temporal lobe. So, let's go to this video. We have three minutes left. I'm almost done. So, we're attracting the orbit. Here, we took off the lateral orbital rim 'cause we thought we needed more exposure, and that's an option, you can take off the lateral of the rim, but we didn't do it in the first case. We're drilling off the sphenoid bone. We'll expose the temporal lobe dura. There's the meningo-orbital band, which we will cut. And that will allow us to retract the medial temporal lobe off Meckel's cave and the lateral wall of cavernous sinus. And we go down inferiorly to the floor, and here we find the tumor and we get into the front of the tumor, and we internally de-bulk it. You can see we're just retracting a little bit on the temporal lobe, not that much, sorry. Taking out more tumor. Temporal lobe is over here, orbit is over here. So, here we're pulling the posterior fossa tumor out of the posterior fossa, doing that very gently and carefully. And at the end, you'll see the trigeminal nerve, here it is, the fascicles of the trigeminal nerve. And then we close with that inlay-onlay button closure with AlloMax, a little bit of teh-seal the orbit falls back into place and we plate the lateral orbital rim, plus oculoplastics closes the incision. Cosmetically, it looks great. Go back to the slides. Here's a post-op showing you, you can see how we went in here, and gross total resection of the tumor. Next, oh, here we go. Oh, this is just showing you the T2. This is cut off a little bit, but it shows you the bone we opened. I can't really see it, maybe I don't know if you guys can. So, just quick lessons on closures, basically, as long as you do a multi-layer closure with some kind of inlay, some kind of onlay and a flap, most of your cases are gonna resolve. And that inlay can be anything, Duraform, Duragen, Duraguard, acellular dermal matrix, your onlay can be anything, could be fat, acellular dermal matrix, fascia lata if you want. There aren't some hard-and-fast rules, but you do need multiple layers, inlay/onlay. You can either stitch them together like a button, you can buttress them like a gasket, or some people don't do any of that. I try to avoid intracranial fat because post-op images are hard to interpret. Fat is okay as an onlay though. You can use Duraform fat and flap. Fascia lata is not required. I've learned that over the years you can use AlloDerm, AlloMax, large thigh incisions and muscle herniation can be bothersome to patients. The other thing I've learned is that lumbar drains decrease the rate of postop CSF leaks, particularly in patients with high BMI meningiomas. Your higher-risk leaks should get lumbar drains, particularly high BMI. This is just showing you the gasket, the nasal pore, sorry, this has met-por holding in a piece of fascia Lata. Now we do it with AlloMax, but it's covered with a nasoseptal flap. Here we used Duraseal, now we use AlloMax. We wrote a paper showing that acellular dermal matrix as an alternative, and we compared it to fascial lata, and we had the same rate of CSF leak. It worked for the button as well as the gasket. And then lumbar drains, this was the randomized study that was done out of Pittsburgh about lumbar drains. And what they basically found is that for patients judged to be at high risk of CSF leak, preoperative lumbar drain in the context of a vascularized flap so that you're not gonna suck in air, significantly reduces the rate of postop CSF leak. So, basically I agree with this. If you think you're gonna have a leak and you have a high-risk patient, particularly high BMI, and this was a paper we wrote looking at meningiomas with high BMI, showing that our number of drains made a difference, a lumbar drain will make a difference. Not everybody needs one, not everybody needs one, but high-risk patients do. If you do a gasket, don't pinch the optic nerves, you can cut out slots for the optic nerves. Last lesson, there are always more lessons. We looked at our learning curve. We basically skipped our first 200 cases, we looked at the next 1,000 cases and we said, "How did we do in the first 500 compared to the second 500?" So, we compared like at times 700 cases to the next 500, and we found that our rate of gross total resection went up. Even after 700 cases, we still did a better job in the next 500 cases, and our rate of post-op Endocrinol comes from pituitary adenomas. Even something as simple as a pituitary tumor, we got better after 700 endonasal cases, if we looked at the next 500 cases. So, final conclusions, neurosurgery is an evolving field. Procedures will continue to become less invasive and more effective. Keep an open mind to new innovations, don't become locked into doing things the way you were taught. And although we must be deferential and ever respectful of our teachers, and the pioneers in our field, I don't wanna take away from that, we also must be cognizant of the fact that they were a product of their times, and what we're gonna do in the future is gonna be different than what we did in the past, and we have to be open to innovations and to new ways of doing things. Thank you very much.

- Great work, Ted. Immense experience, obviously, over 20 years. I'm very appreciative of providing all those pearls of technique. There was a couple of questions, especially for patients who have a lot of frontal-lobe edema, and their brain can be tight, especially through a small craniotomy. Do you use lumbar drain?

- No, we do not use lumbar drain. This is for the eyebrow incision, I assume they're asking, right? So, if you get down to the cisterns, you're working right underneath. If you take the orbital rim, there's very little brain retraction and you have to do use dynamic retraction, pull down on the frontal lobe, get to the cisterns, open up the cisterns, and wait. And if you drain the cisterns and wait long enough, the frontal lobe will start to fall away. You also have to position, extend the head when you position the patient so that you can get that drainage, and the frontal lobe will fall away.

- Okay, another question was, how's been the recurrence rate for your cases endonasally? As you know, it's less exposure, no question, it's the less aggressive resections, although there are visual outcomes are better.

- Wait, what are we talking about? For which tumor type? Sorry.

- Let's say some of the larger tumors we removed through the nose.

- I don't think it's less-aggressive resections, I don't think that's a true statement.

- So, how-

- if I think I can't get the whole tumor out endonasally and I wanna get it out, I'll do a craniotomy. I'll only do the ones that I think I can do as aggressive a resection as if I could do it through a craniotomy.

- What's been the recurrence rate endonasally, any ideas?

- Yeah, we actually published that. So, we looked at our planum tuberculum meningiomas, we also looked at our craniophrangiomas, which hasn't come out yet, but the other one is accepted. For our planum tuberculum meningiomas, if we got a gross resection rate, we had one recurrence and that one differentiated into an atypical meningioma. So, it may have had more to do with the fact that the type of tumor she had. I didn't present that data because it's new data, but I think the paper may be accessible. It was written by one of my fellows, Brett Youngerman. We looked at our long-term outcome after endonasal surgery for meningiomas, and sah-gnio gah-deel looked at our long-term outcome for craniopharyngiomas, and the rates were very, very low, and it's in the literature.

- Okay, beautiful. Well, I think with that in mind, I wanna thank you very much, Ted, huge experience, very, very beautiful perusal of technique, and most importantly, a very balanced approach. I think it's important not just because you have the hammer, everything looks like a nail. I think skull-base surgeons shouldn't be divided in open or endoscopic.

- On that note, Aaron, one quick thing I wanna say, most people think that I do mostly endonasal surgery, but my rate of craniotomy to endonasal is two to one. So, of the, let's say 300 cases, I'll do 100 endonasal, but I'll do 200 craniotomies. So, even someone who does a lot of endonasal, you're still doing the majority of your surgeries need to be done through a craniotomy. And that's exactly what you were saying, not every patient is a good candidate, and just because you have a hammer, doesn't mean everybody is a nail. I completely agree with you.

- Yeah. So, no, I agree with you. I think a balanced approach is the key, and that's what I like about your approach. You approach it based on pathology rather than based on expertise, which is extremely important in skull-base surgery. At the end of the day, which approach will provide best outcome for the patient, not letting the pathology fit the expertise of the surgeon. So, with that in mind, I wanna really thank you, Ted, for taking the time, being with us this evening, and look forward to having you with us in the near future.

- My pleasure. Thanks for having me, Aaron.

- Thank you, Ted.

- Take care.

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