Transcript

- Hello, ladies and gentlemen, and thank you for joining us for another session of the Virtual Operating Room from the Neurosurgical Atlas. Our dear guest today is Dr. Bill Couldwell from the University of Utah. He is the professor and chairman there. He doesn't require any introduction. He's internationally known for complex intracranial surgery. There's one word that really encapsulates Bill very well, and that's a mensch. I've worked with Bill for many years, both as colleagues, and now at the level of him being the Editor-in-Chief of the Neurosurgical Focus. I can tell you, that he's not only an incredible surgeon, amazing family man, and also, really, a dear friend. Bill, we know that you have a huge experience with resection of skull-based meningiomas, and I'm really honored today to have you with us, and I'm looking forward to learning from you. So with that, let's go ahead and discuss through the lecture. But before we do that, I was interested in asking you an important question that many of us struggle with every day. And that's, what is, how do you define a master surgeon? What are the pitfalls that young neurosurgeons need to watch for in their journey toward becoming a skilled neurosurgeon that they can avoid? And what are the typical pearls you give to younger neurosurgeons in terms of being a technically superb surgeon?

- Well, thank you, Aaron. Thank you very much for that kind introduction. It's really an honor to be with you again at the Virtual OR. That's an interesting question, and I can only speak from my own personal perspective, and the philosophy that I impart on my trainees. In that, first of all, I think a master surgeon is a lifelong student of anatomy. And I think Professor Rhoton really taught us that over his whole career. And we're constantly learning, and it's a humbling business, especially some skull-based surgery. And I think it's important for the young people to learn from the more experienced people, and understand that they're not going to be a master surgeon overnight. It's a lifelong endeavor. And we do... For instance, I do things differently now than I did when I was training, and I'm still refining and learning better methods from my colleagues. And there's a lot to learn, because I think we're all looking at the same disease, but I'm always interested in seeing how people grapple with the same problems that I see. And it's important, also, to learn from your mistakes. I can't tell you how important that is. I think good surgeons learn from their mistakes. They're not paralyzed by them, but they, basically, pause, learn what they can, and then move on, so that they can carry better care onto the next patient. I think that's a very important aspect, because you have to learn that you can't be devastated by your mistakes, and paralyzed by them, but you need to be able to learn from them. So you can't be bold, so bold, that you're not learning from them, but you also need to be able to move on, and then refine your techniques.

- Yeah, I think-

- And then I've also benefited from some absolutely fantastic surgical mentors. Marty Weiss, Taka Fukushima, probably the most important ones in my own learning curve. And that I'm learning from all of my friends every day.

- Bill, I cannot agree with you enough. I think the two factors that I wanna echo as well, is that we can't be really bogged down with dogma or bad results. We have to always remain innovative, retain our enthusiasm and passion for technical excellence, and be able to deal with bad outcomes. I think many people would say, this quote, that, "If you don't have complications, you don't operate enough". It's how we deal with our complications, both intrapubably and outside the OR, that define who we are. So I really appreciate, again, your incredible skills, both in surgery and your experience, and very much looking forward to this exciting lecture. Please, go ahead.

- Well, thank you. Well, I thought I'd talk a little bit today about some of the things that I've learned over the years, and some of the mistakes that I've made, and how I've overcome some of those issues. This is where I work. It's a beautiful area in the foothills of the Rockies. And this is our medical center, and our neurosciences center is over here on the left side. And this is our complex. But Utah is blessed with some of the most beautiful natural parks in the nation. I don't have any relevant disclosures. And the three things that I would really like to impart on you today... First of all, let me get my marker going here. Are, we want to preserve function in cavernous sinus meningioma. I think that's an important one, and I'm gonna show you my personal philosophy about how to do that. The importance of orbital surgery. I can't tell you how important this is. This is an emerging area in skull-based surgery, and it's been a sort of a no man's land for most neurosurgeons during my career. But I think we've got a great understanding for it now, and we chase disease into the orbit routinely. And then respect for veins, and I'll talk about this, how important this is over your career when you're looking at operating on meningiomas, especially. So the interesting thing is, is that we have a very large catchment area. We're the only academic medical center for this large area, which is not heavily populated, but together, it counselors many million people. And we often get this type of a patient coming into us. And the reason I show this scan is really to just emphasize that, what is the treatment for this? So this is actually an adenoid cystic carcinoma. But this woman had lost vision two years previously, and she's got this massive tumor, and we don't have any evidence basis for the management of treatment, and surgical treatment, of skull-based tumors. So we have to rely on experience, and the cumulative experience from those people who've done a lot of this surgery, to guide our treatment. because we don't have any cookbook treatments as some of the much more common diseases have. So I operated on this in two separate sessions, a transcranial approach and a retrosigmoid approach for the posterior fossa. But the importance of the skull-based meningioma is, really, the real estate rule. It's the location of the tumor. And we're often dealing with these tumors in these very difficult locations. I think this is probably... This and large craniopharyngiomas represent the most difficult lesions that we treat. I think it supersedes all vascular disease in a lot of ways, because these patients often have a paucity of symptoms, and then have, can have terrible complications associated with their treatment if we're not careful. Now, this is a classic diagram of the classic areas where meningiomas occur most frequently. And what we're going to be doing, is we're gonna be talking about this region here, and I'm gonna be focusing more on the region of the cavernous sinus paracentral area, and the posterior fossa. I'm not gonna talk about the simpler tumors, in my mind, the anterior skull base tumors that are often treated either endoscopically or transcranial approaches, but don't have the same risk for cranial nerve injury that the middle fossa, cavernous sinus, and posterior fossa tumors have associated with them. So you can have a patient like this. This is actually a physician who actually took early retirement, because he thought he was depressed, and he had a decrease in cognitive function, and had this skull base meningioma with a lot of hyperostosis. You can see this associated with this. And a lot of edema in the brain. And we do an aggressive removal, and we can have a remarkable turnaround and improvement in function. And he actually went back to work six months after we removed this tumor, and he's still working now. But let's talk about, I think, sort of this archetypical difficult meningioma, which is these tumors that occur in the region of the skull base and the cavernous sinus. And this is an important area because of all the cranial nerves that traverse the area. The carotid artery is coming through the region of cavernous sinus and the anterior loop. And the optic nerve, of course, just above the cavernous sinus through the canal, and overlying the cavernous sinus tumor. So if you have a tumor in the cavernous sinus, it often involves all the nerves in this area, the carotid, and may compress and involve the optic nerve, both in the intracisternal portion and in the canal. Now, I update this it Epocrates website yearly. And it's interesting, because if you look at the growth of incidental meningiomas, and I'm really emphasizing this for the younger people, because I think, in training, we're not emphasizing enough the outpatient management of a lot of these tumors. But if you look at the data for the management of incidental lesions in meningiomas, 60% of these tumors have no growth over five years. Now, there's not a large series looking at cavernous meningiomas in particular, but this is an important factor, because we often see, and I have hundreds of patients that I see that have meningiomas identified with MRI studies for surveillance studies for tumors elsewhere, or they're fallin' on the ice in the winter time, and hit their head, and they have an incidental meningioma. And unless they're younger, T2 hyperintensity is an important one. I often offer the treatment of just following them along. So we're left with this quandary about aggressive removal. Can we improve tumor control and avoid radiation, versus a subtotal resection, where we're trying to preserve neurological function. And this is very, very important and delicate balance in meningioma surgery. So initially, I think in meningioma surgery, our goal was to improve survival. And this is a very important study that was published in 1957 by Donald Simpson, showing that the more aggressive we are with the resection of these tumors, that the better the survival was, and the recurrence rate would be less. And I think it's important to identify, that even in today's current treatment modalities, using radiation, et cetera, surgery is an important element, as is demonstrated here. That you can have surgical resection of these tumors, and you can improve survival. Even in malignant tumors, it's less effective. But in the benign tumors, absolutely. And what we see here, the important predictors of mortality in patients with benign meningiomas is the extent of surgery, and often, radiation as well. But surgery is still important. And even in atypical and malignant tumors, we have the same effect. It's less, but it's still important, the extent of surgery. So let's remember to try and get the tumor out as best and as safely as we can without incurring neurological deficit. What I think has become more important recently is this whole aspect of trying to improve neurological function with surgical resection. Now, it's easy in a case like I just showed you of that physician that had the large tumor in his frontal lobe with a lot of edema, but what do you do in these skull base tumors? And there's been an evolution of treatments in my own career. I've become less aggressive with cavernous sinus, initially, and I became more aggressive with spheno-orbital tumors, cranio-cervical junction, and recurrent tumors, and I'm gonna discuss that. So as I mentioned, the cavernous sinus is an important area for meningioma growth. And if you look at meningiomas in the cavernous sinus, they are the most common primary tumor in the cavernous sinus, even though they represent only 1% of all intracranial tumors, but they're difficult group. As I said, they encase the carotid and the cavernous cranial nerves. Here's an old picture from "Grey's Anatomy". But what you can see here, and I just wanna point this out, is you could see the lateral wall of the cavernous sinus outlined here, and the tumor's growing both within the cavernous sinus and beyond the cavernous sinus. So that really renders the whole idea that maybe you don't want to remove all the tumor within the cavernous sinus, for worries of increasing neurological deficit, knocking cranial nerves out, if they're functioning now. But you can remove a lot of the tumor outside the cavernous sinus. The other thing that I would like to say that, remember that the cavernous sinus is enclosed with a dural leaflet over the top, down the sides on both sides, and then extending to the middle fossa dura. And this is a closed encased space, and when tumors grow there, they can cause compression of structures. So this is how cavernous meningiomas present, and you can read the list here. But the most important one, I think, is this ocular motor deficits, and also change in visual acuity, which is the most common presentation. Less likely, the fifth nerve is involved, and much less likely, pituitary dysfunction, and usually when there's growth over towards the sella. So if you look at the treatment options for cavernous sinus meningiomas, you can see that we can operate on them, and I'm gonna show you that. We can use radiosurgery as primary treatment or secondary treatment, or we can use no treatment. And I think it's important to remember, that we don't have good studies on the specific natural history of the cavernous sinus meningiomas, but we can get insights into this from our surgical series. I just wanna point out this series in 1996. This was Sam Metty series, and also, was verified by Shekar, who now is in Seattle. But the progression-free survival and the recurrence-free survival of these tumors, and this differentiates those tumors that were removed completely. The recurrence-free survival, and the progression-free as tumors that had subtotal resection was not much different. And you could say, well, the treatment was effective, but you could also say, that there wasn't much of a difference, whether you remove the tumor completely or incompletely. And so you're looking at the natural history of the tumor. So we also know, that if we use radiation treatment for cavernous sinus meningioma, it's very effective. And we can look at the risks associated with complete treatment. And this was a series of 88 at the time, 20 years ago, or 30 years ago almost now. And you can see, 76% total resection, but 20% new permanent cranial nerve deficit. And the treatment for radiation is very good. It exceeds 90% control rate over 10 years in many series. So often, people have just defaulted to using radiation treatment for primary cavernous sinus meningioma. We also know, that there's been several studies done by different authors showing that there's actually infiltration of the carotid artery and intercranial nerves. So these often defy surgical resection, unless you remove those structures. So if we look at the best current radiation treatment for cavernous sinus meningioma, you can get improved cranial nerve function in some, new cranial nerve deficit in 5%, and a overall complication rate of 11%. And I wanna show you a surgery that we've done that can improve upon those results. And also, you're left with these tumors, well, you're not going to radiate this tumor. This patient has a symptomatic mass cranial. So we can remove the tumor, and then try watch, or else, treat the residual in the cavernous sinus with radiation. I developed this little operation about 15 or 20 years ago, and I'll just show you maybe Luke, if you can go ahead and show that video for me? And this shows a cavernous sinus meningioma with extension into the middle fossa and into the sella. And what we're going to do, is we're going to remove all the tumor that we can safely, and leave the tumor in the cavernous sinus proper. So we'll start with a frontal temporal craniotomy, and we'll decompress the nerves at the base of the skull. Here's foramen ovale. You can see the tumors involving a V3 there. And then we can peel up the lateral wall of the cavernous sinus, and this is in the face of invasive tumor. You can find this plain, and peel up the lateral wall. Here's the clinoid. We divide the ligament, and we're gonna go ahead and decompress the optic canal, and remove the anterior clinoid process. We'll drill the clinoid here. And then go ahead and remove the clinoid. And it's important to try to get the tumor away from the optic nerve, 'cause a lot of these patients have visual loss, and you wanna decompress the optic nerve. There's the clinoid triangle, superior orbital fissure, and here's foramen rotundum. So we're peeling the lateral wall, and it's important, you can find this plane here between the cavernous sinus and the nerves. And then we'll go ahead and remove the tumor intradurally. So we'll open up the dura, and remove the tumor intradurally. There's some 88 from the temporal lobe here. And then what we'll do, is we'll focus on the roof of the cavernous sinus right here. And we're gonna remove all the lateral wall with the tumor involved. So we go behind the tumor in the posterior aspect of the tumor, and then go ahead and remove the lateral wall of the cavernous sinus by making an incision right here. So you can see, I'm following along the roof of the cavernous sinus here. There's the carotid right there. And peeling up the lateral wall of the cavernous sinus. And once you've peeled the lateral wall, then the last thing to decompress is the third nerve. And I can't emphasize the importance of this. The third nerve often gets, It's like a napkin ring around the third nerve as it enters the oculomotor cistern right here. You can see it, where it's creased. And then we'll, lastly, decompress the optic nerve directly. We'll open up the dura over the optic nerve, drill the optic canal, and open up the falciform ligament. So we've effectively decompressed the nerves, the optic nerve III, IV, V, and VI within the cavernous sinus indirectly, and removed all the tumor extra cavernous. And you can see the post-op scan. So we just published a series of these patients, and you can see the pre and post-op on these patients. We'll move on now, Luke, and I'll show everybody the results of these. But here, you can have a tumor that's involving the cavernous sinus with a large extra cavernous component, and we'll leave the residual within the cavernous sinus proper. And how did these results compare to radiation? Well, again, if we look at the most modern techniques of radiation in the current literature, and compare them, we can see that decompressive surgery improves vision much more than radiation. So 42% of the patients improved in our series with long-term follow-up. Only 13% in radiation. And then more importantly, the oculomotor function. So in those patients with cranial nerve III, we had 50% of them improve. Now, in radiation, they do pretty well, too. About the same results with the III nerve. But look at the difference in sixth nerve. Here's the sixth nerve. 81% with a decompression surgery, where there's only a real minority of the patients with radiation. So this is why I've gone to doing the decompressive surgery if the patients have cranial nerve deficit to start with. And then following them along, or treating them with radiation afterwards. If the patient is older, and if they've got a positive symptoms, and they improved a lot after surgery, we'll watch them, if it's a grade I meningioma, and we'll treat them if it grows, or if they have new symptoms. So here's an example of this in some indirect evidence, that there's actual compression going on within the cavernous sinus. Here's a woman. And if you look here, she's got meningiomatosis, but she's got this cavernous meningioma on the right side pre-operatively. And look at this, the caliber of the artery here, compared to the contralateral side. And you can see, it's smaller. Here's her post-op scan, and you can see, she's got normal carotid that equals the other side now. And she had improvement in her sixth nerve palsy before we gave radiation treatment. So that's the case I make simply for considering surgery in cavernous sinus meningioma. A light surgery upfront, try to take everything you can outside the cavernous sinus, following along the Simpson grade removal, and the statistics for survival, and then giving radiation if they're symptomatic from residual, or if it's growing. Now, we can do this through a smaller approach. We can use, actually, a lateral orbitotomy approach to perform the same objective. Here's a 70-year-old man with visual loss, and you can see, he's got a cavernous sinus meningioma. There's some compression of his canal and his optic nerve. And we'll go ahead, and Luke, if you can just show those videos, I'd appreciate it. So we'll use a lateral canthotomy incision in this. And if all you're trying to achieve is to lift up the lateral wall, and remove and decompress, remove the clinoid, and decompress the optic nerve, you can do it through this little incision. So we'll fork the incision up into the carl pupil area to just give us a little bit more room. But what we're doing, is we're focusing on the lateral orbital wall, and we'll free up the lateral orbital wall here from its periosteal investment and the temporalis muscle just behind it. And then remove a little window of bone of lateral orbital rim. And the idea here, is that we'll go down the lateral orbital wall as a shorter distance to the cavernous sinus completely extradurally, and we'll free up the periosteum here. We start at the level of the zygoma, and go about 15 millimeters above it. I'm using a reciprocating saw here, but you can use a, we'll use a C1 on the Midas as well, and that works very well. Protect the periorbital while you do this, and then make the inferior cut. And the zygoma is right in this region here. And then remove this little window of bone as a bone flap. Now, after the bone flap's removed, we'll go ahead and follow down the region of the lateral orbital wall. Now, we do this just by thinning the lateral orbital wall. It's helpful to have image guidance. We use CT on the image guidance, because it's all bony work. And then come down the region of the lateral orbital wall, and thin this out. And then, Luke, I think we can go to the next clip now. Now, what I'm doing, is I'm lifting up the lateral orbital wall, and we're going to show removal of the clinoid process, and the optic canal decompression. So I'm removing the anterior clinoid process here. And the optic nerve is completely decompressed, okay? Right there. So there's no closure. We entered the dura here, because we removed the lateral wall of the cavernous sinus. And we'll just re-plate the bone, and use a soft tissue closure for the skin. And then we can go on now. Thank you very much. And this is what he looks like six months later. And you can see on the bone windows here what's been done. We've removed the clinoid, we've decompressed the optic nerve, and we've removed the lateral wall of the cavernous sinus. And this is his incision here. It's cosmetically very acceptable. You don't actually interfere with the temporalis muscle, so there's no temporalis waiting. Now, if all you want to do is decompress the cavernous sinus and remove tumors as safely as you can, and there's no optic nerve involvement, then Rudy Fahlbusch and Michael Buchfelder, in 2008, published this series, which I think is excellent. And the idea is, that they come in trans-nasally, and they do an indirect decompression of the nerves, and removing tumor in safe zones from the trans-nasal approach, decompressing the pituitary gland here, and removing the tumor there, and decompressing and removing the inferior aspect of the tumor, and staying out of the nerves. And they found very similar results, in that they had good decompression of the cavernous sinus, and had similar results with their cranial nerves. So can you show this video now? So I just wanna make a case, that it's useful to explore the cavernous sinus in some of these tumors, and not just immediately think about radiation. Here's a 13 or 14-year-old girl with progressive problems with her III nerve, and some recent visual loss, and she's got a lesion in her cavernous sinus. And she had seen several people, and they had just recommended primary radiation treatment. But I wanna show you that you can find some of these meningiomas that are not infiltrative. I actually thought this was going to be a nerve sheath tumor initially, probably from the fifth nerve, but she had no fifth nerve symptoms. So we'll go ahead and do our orbitotomy approach, just like I showed you in the last video. And once we get down there, you'll see what we find. So we'll thin out the lateral orbital wall. We'll go through the Tarion. we'll come down the lateral orbital wall. We'll thin the latter over the wall and get down to the region of the cavernous sinus. Now appealing up the lateral wall of the cavernous sinus. We'll use image guidance to verify our location because we're drilling through the bone and here you see the fifth nerve. Now I'm looking for a window to get to that tumor. So I do find the tumor and it's like a nugget. And I was surprised this was actually a meningioma of the cavernous sinus, very focal, very discrete. And we're able to remove this and come around this completely. This is between V1 and the third nerve. So she presented with third nerve palsy and we're able to dissect around the tumor and pull it out like a little note. So given her young age, we've had a complete removal and we'll go ahead and close. Again, closure is simple. We'll just make sure that there's no tumor left behind and we'll go ahead and close that, we never opened the during in this case. And we'll move on Luke, if we could. And she actually had improvement in third nerve and we've not radiated her at this point. She's had no recurrence and I followed her for several years now. So I also wanted to remind people that radiation of the cavernous sinus is not a completely benign thing to do. Here's a woman I'll show you. She's 38 years old. She has radiation for a cavernous sinus tumor. And you can see here, that I actually did not follow her initially, but I followed her up after she had been radiated. And I saw her every year and the tumor remain stable was great control, was well done radiation. She had optic neuropathy and she was blind in that eye, but the remaining aspects of her neurological function were normal including our extra ocular movements. So we were following her along with no further treatment. Then she presented with this scan and I wanted to show here, there's a big intracerebral hemorrhage. She was a phasic and hemiplegic from this with an intramuscular hemorrhage. So we treated this, we did an angiogram and she had complete carotid occlusion. So remember that we use radiation treatment for ABMs. And I think it's important to realize that a number of these patients will go on and lose their carotid over time. And I've seen it time and time again. And I have a series of these patients were just getting ready to publish now. And when they lose their carotid, they can become symptomatic. So here's another case, 40 year old woman radiation. And she's developing ischemic events because they're carotid being included from the radiation and the tumor growth probably, but she had stable tumor in this case. And she had previous radiation and she's got obviously hypoperfusion in the left hemisphere. So we went ahead and did an STM-MCA bypass on her to treat her, and we've been following her along. So a number of these people will develop cranial nerve palsy is obviously from radiation, which we see in a delayed fashion usually, and also vascular complications. So the next topic I'd like to move on to is that the contemporary skull-based surgeon needs to be an orbital surgeon and Dr. Roten left us with a great legacy of all his work, demonstrating all these cadaver dissections. But it's important to remember a few things, a lot of the disease that we deal with cranially enters the orbit. Meningioma case in point a as of today's topic. And it's important to realize that when you know the cavernous sinus, you can just follow up the nerves to the region of the orbit. And there's a general tendency for things to start off laterally in the orbit and go immediately. So the ophthalmic artery, the third nerve, the fourth nerve, which crosses the third nerve at the superior liberal foremen. And also, you can use these oral approaches to be able to chase disease into the orbit as necessary. So here's in a close-up of the fourth nerve crossing, the third nerve at the securable fissure, the optic canal. And remember that the falciform ligament becomes the optic nerve sheath. If you follow up the dural sheath in time. So you open up the falciform ligament remove the dura that's separate from the optic nerve to decompress it, then it merges into the optic nerve sheath. Be careful of the ophthalmic artery coming in laterally and underneath the nerve in this case. And here's this general lateral to medial progression of the nerves as they go forward. The third nerve revise into a superior inferior division, and we've written a lot, and I've also published videos on orbital surgery and chasing tumors into the orbit, but it's an easy structure to learn and also an easy thing to teach in the skull-based lab. And we wrote this overview of approaches to the disease within the orbit. And I think it's fairly simple. And when I think about approaches to the orbit, I think about enteral lateral and approaches, which are usually transcranial, they can be orbital cranial, like I just showed in the previous videos, but you can use a standard frontotemporal, super orbital keyhole or transorbital cure lateral orbital wall approach. These are anterior and superior approaches. And then if you have disease, that's inferior depending on where it grows or what you're trying to achieve. Then we often use the transmaxillary approach or transnasal approach to get to these diseases. An example of this would be this approach that we'd use to approach a medial and inferior overall lesion. This was a maningioma, and maybe you can show this video, Luke. And the anterior skull base approaches are beautiful to reach this area. And we do this with our IMT colleagues, but they require no retraction, simple approach in and out quickly. It's very, very handy to use the endoscope in this. In this particular case, this gentleman was had diplopia and also have proptosis and some visual loss. And he had this lesion in the medial and inferior aspect of the orbit that was compressing the optic nerve here and see that there. And we'll go ahead and do an endonasal approach, medial turbinectomy. And then you, what you want to do here is you wanna remove the medial wall of the maxillary sinus. And so you can see the inferior aspect of the orbit well. And you'll see, after removal of bone, we can expose the posterior, inferior aspect of the orbit. So we're peeling off the bone of the orbit and here's the inferior aspect of the orbit. This is over the lesion right here. And what we'll do, is we'll use standard neurosurgical technique. Once we find the interface with the tumor we'll debulk the tumor. And then go ahead and remove the capsule, the tumor and its pedicle. Use bimanual technique. And then go ahead and remove the tumor and cauterize the pedicle as you'll see here, We found the pedicle and we can remove this. And this amount of orbital wall removal, we don't actually reconstruct here's periorbital fat. The periodical fat is a great buffer and it's a very safe area to operate in. And neurosurgeons need to be more familiar with the approaches and be aggressive about removing tumors in this area. Can I have the next slide, please? Thank you. Here's his post-op scan. And of course meningiomas when they involve this phenyl orbital region are a real problem. And the problem is, is that they often start in the middle fossa and they can be intradural lesions, as this case was. This was a case that was removed in the community, and the patient came back to me and said, "you know, they keep telling me that there's no tumor, but why is my eye getting worse?" And these patients have uncomfortable eyes they're prop tonic, they're engorged. They've got bad venous drainage from the eye. And the reason is, because these are often associated with hyperkeratosis. Here's a very dramatic case. This is a woman from Eastern Europe that came in and you can see that what's involved here is the tumors involving the orbit. It's involving the extracranial space and it's involving the middle fossa here as well. So what you're seeing is you're seeing proptosis, you're seeing adema in the frontal lobe as well. And she actually, and this is incredible proptosis. You can see on the scan. So what we'll do in this case, is we'll do an aggressive surgical surgical resection of all the involved bone, Sam Metty taught us many years ago that the bone is tumor, there's tumor involved in the high prostetic bone. And I have developed a very aggressive approach to these tumors. And we'll go ahead and remove all the bone that's involved with the tumor, both the roof here and the lateral orbital wall. Now, usually these tumors do not involve the super orbital rim, which is right there. And that's actually very convenient, because that is a good landmark for you, and you don't need to remove that bone in most cases, and you can remove all the bone behind the rim. So here's another example. Here's a case of a gentleman who had a middle fossa meningioma, but he's got this big recurrence with high prostosis. And what we'll do is we'll do an aggressive resection of all the bone in this area. So there by allowing the eye to return to its native position. Let me show you a Luke, just go ahead and show this this video. This is a woman with a terrible proptosis, this is one of the worst cases that I've seen, except for the last case, I'm gonna show you. But she came in and extremists because she had so much edema around the tumor and she was starting to herniate trapper ventricle you'll see on the scan. So we had to move quickly on her. So you can see this high prostosis and the terrible proptosis. So you can see she's got a lot of midline shift. She's actually midlines and she's herniating her temporal lobe a little bit here. And we'll go ahead and, so here's the medial temporal horn actually almost to midline, which is ominous. And so we'll go ahead and plan to remove the tumor and try to reduce the proptosis. So that's going to require going into the orbit directly and removing the tumor. So frontotemporal approach, and we'll go ahead and open up the dura and or the temporalis muscle, and then expose the hydrostatic bone. And the minute you get in here, you'll see that there's tumor involving the bone and even the temporalis muscles. So we'll go ahead and drill out all the involved bone here. 'Cause all the involved bone has to go is thickened. It's very, very involved with tumor and very vascular you'll see. If people will ask me, do we ever embolize these cases I used to, but I've given that up the, because I've had some complications with ophthalmic, ethmoidal anastomosis and some visual loss with embolization in this area. So I've given this up in the anterior cranial fossa and the cavernous sinus region. So we'll go ahead and remove this very enlarge clinoid here. And then you can see the optic nerve right there and we'll go ahead and decompress the optic nerve. Then we'll open up the dura and remove the tumor from the intercranial cavity that we're all familiar with. Separating the parasitized vessels from the brain, these tumors, parasitize the appeal supply of the brain, especially the ones with the adema, which is a good indication of that. And then we'll go ahead and remove all the tumor involving the durum. Now the next step is the important one that I wanna show you because it involves removing the tumor in the orbit. Now, if you start behind the orbital rim, which is right there, you identify the clean plane here between the tumor and the dura. So what I'm doing is I'm dissecting off the peri-operative or the periorbital it's involved with tumor from the periodical, other than the orbital fat. And you follow it right back to the region of the annulus of Zinn. Now, in most cases, you don't need to remove the tumor at the annulus of Zinn because it peters out. But if it does involve the cone and the attachment of the muscles of the comb, you'll have to decide whether you're gonna remove some of the muscle we didn't need to in this case. So we'll go ahead and close the dura. And then I've abandoned reconstructing the orbit because I'll show you why with the proptosis results. But we got into the maxillary sinus here and we got into the frontal sinus. So we'll plug that off with some muscle plugs and fibrin glue, and then go ahead and place some fat between the orbit and the, the dural reconstruction. Now, since we removed all the bones in this case, I wanna show you here, look at the optic nerve. It's like a road course now. So the eye is completely now reduced. So two weeks later, we bring her back for a custom cranioplasty because all the bone had to be removed in this case, we didn't have a bone flap to put back in and I'll show you the results of her proptosis on the right side. So we'll put our custom implant in and close and then show you the results of the eye. And here you can see the pre-op here and the postop here. So she's had complete reduction of a proptosis. So that's the reason that I've become very aggressive with these patients. So when I look at the results of these and I have a very much larger series, now this is we published a few years ago. We had this index we use as a proptosis index, the amount of the I was proptonic. And you can see that none of them became enauthamic with this operation. So this is a completely different entity. If you take a normal orbit and decompress, the bony decompression, like I showed you, you will end up with enophthalmos, but you don't end up with enophthalmos in these patients that have a lot of proptosis to start with. 'Cause I think there's so much fiber healing around the tumor. And after the tumor has been removed, that if you don't, if you're not aggressive with removing it, you won't reduce the proptosis and you can see even some of them, we didn't get complete reduction of the proptosis. So I become very, very aggressive with this and for time I'll move on. So, this results suggest that aggressive surgical resection of the meningioma can result in significant proptosis improvement. I've completely abandoned, reconstructing the orbit in these cases for the reasons that I've mentioned. I just wanna mention a few caveats about petrocliva meningiomas and you know, these are very, very risky tumors. As I mentioned at the beginning, I think they are the most risky meningiomas and intracranial tumors that we deal with. I define them by those tumors that attach at or medial to the nerves at the base of the skull. And so the idea being is that the surgeon has to work between the nerves to get the tumor up and that's the complexity and the difficulty with treatment. So this is the interoperative picture that you're familiar with the petrocliva meningioma. So this is the typical case. This is actually spheno petroclival tumor. It sits like a saddle. It was originally described by Cushing. It's just like a saddle over the petrous apex. And these are very, very treacherous tumors and often require more than one approach for removal. The problem being with these tumors is that they have very little symptoms comparative to their size because they're often slow growing and the cranial nerve palsies can present at time of diagnosis, but more importantly, they can be a real risk for us at surgery. They have a lot of vascular and casement, a lot of bone abnormality. A lot of them involve the cavernous sinus as well. So you'll have to decide how you're gonna deal with that. So these are the most complex treatment managements that we have within neurosurgery in my mind. Postoperative neurological dysfunction, I think is an important one. Cranial nerves are the most important one. And about a third of our patients end up with new cranial nerves palsies. One, we had this original series, although more recently we're just compiling our up-to-date series and it's less than that. Used to be high mortality associated with them. We've reduced this quite extensively, but it's still an issue. And radiosurgery gives good tumor control. The problem is it's not applicable to these larger tumors with lot of brainstem compression, but we use it as an adjunct for the cavernous component, as I mentioned, and also the tumor that's unable to be removed 'cause it may be invading the nerves. I think a couple of tricks that I've learned over the years. This is actually talk is approach Fukushima. You wanna pull the arm down to get it out of your way. I do these tumors in the lateral position, usually retrosigmoid or combined petrosal and pad the patient well, these are often long surgeries and a lot of cranial nerve monitoring. Let me just show you this case, 'cause I think it shows you the complexity of the tumor and the location. This is a young woman who was actually a very competitive gymnast and she had difficulty on the balance beam and it was a remarkable that she was as competitive as she was as an athlete with this tumor. But you can see this is a petrotentorial tumor, but you'll see the tumors attachment is medial to the cranial nerves. And it represents a type of a problem that we see with these tumors. In that it's important try and get this tumor out properly. She's so young and here's her position notice the shoulders pulled down. We put the upper arm on an arm rest on an airplane rest and we'll do this tumor retrosigmoid. And we open up and identify seven and eight. And this tumor is attached medial to seven and eight. And the fifth nerve is deep to us here. So we'll go ahead and make sure that we clear out the canal completely of seven and eight so that we don't have any hearing problems down the line, if there's any tumor growth. And we'll drill the canal and make sure that we removed all the attachment around the internal auditory canal. And this is a preemptive move to try and reduce the risk of hearing deficit down the line. So we're drilling the supermiatal prominence there, and this gives us a better view medially to the apex of the petrosal nerve. There's the fifth nerve. Now I haven't seen the fourth nerve. So what we'll do in this case is we'll go ahead and debulk the tumor and look for where the fourth nerve is. And this was a very vascular tumor. It was actually hemangiopericytoma. It was not just a regular meningioma, was a aggressive a tumor. And what I'm doing is, I'm cauterizing the attachment of the tumor and looking for the region of where the fourth nerve is. And what happened here, is that you'll end up seeing the fourth nerve was in discontinuity in this case, after removal of the tumor. 'Cause this tumor can involve the region where the fourth nerve enters the tentorial edge. So remove the tumor, remove the capsule of the tumor and find the fourth nerve. There's the attachment of the tumor, right where the fourth nerve enters the tentorial edge. So, remember that the sixth nerve and the fourth nerve are single function nerves, they innovate one muscle. It's an important lesson. And you can reanastomose these nerves, if you have room like in this case, the tumor had stretched the nerve out so much that we had room to be able to reattach the fourth nerve and repair this. So six and four, I'll always repair for this reason. Third nerve is terrible. It's a multi-function nerve. We'll go ahead and close. And she did very well and ended up because it was meningeal pericytoma she had post-operative radiation to the bed and she's done very well over the years. Thanks, Luke. I wanna show you this. This is a neurosurgeon's mother and she had a little bit of visual loss in her left eye. And if you look at this carefully, here's a clival meningioma midline. Look at the basilar artery. It's completely encased in the tumor What would you do with this case? Well, I thought that if I removed it aggressively, I'd certainly make her worse, she was in her sixties. Here's the tumor and you can follow the basilar artery directly inside the tumor. So look at the images carefully. See what the relationship is with the vasculature. So what would you do with this case? Well, she had visual loss in her left eye, so I did a simple, a little operation where, I don't know if you can show that video or not Luke, but where I just decompress the optic nerve on the left side. Now, this is the technique that I use for optic nerve decompression. And what I do is, I try to indirectly remove the tumor first. So take the tumor out lateral medial to the optic nerve and gently pull the tumor out from behind the optic nerve. I don't move the optic nerve. I work on the tumor from both sides. Don't touch the optic nerve, if I can't, then you have to open up. And again, like before I showed you, we open up the dura drill the canal. This gives you much more breathing room for the nerve and then open up the falciform ligament. Remove the clinoid. So they don't have any recurrence that's gonna cause early visual loss. So, to remove the clinoid process, and then open up the falciform ligament. And you can see this tumor was in the falciform ligament was causing a crease in the optic nerve. Thank you, Luke. Okay, so I followed her now for many years and she's had actually no change in her symptoms at all, and we haven't even radiated the tumor. So, I think in some cases less is better. And I wanna talk lastly about venous problems. And I think this is the next frontier. We really don't have an objective way to measure venous flow. And I think it's a very important thing. So the really the issues are do we sacrifice or try to repair the sinus or the major vein? How do we manage incidently thrombosed sinus on post-operative image? I think it's controversial. Do we do a radical tumor removal involving the sinuses if they're still open? Do we do radiosurgery now or wait and scan? I think these are all controversies. I think that as we get older and we have more experience, I think you'll see in the data that I'll show you, that the surgeons are more concerned about the vein. And the consequences of venous sacrifice are not predictable. And I think this is an important one, but we can use experience to help guide us. So, we've published these cases where we involvement of the torcular in search. We'll do angiography in these cases DSA, look at the venous studies, see what's included. And remember, these people are compromised already. They're down already with venous flow. And so you wanna be very careful about taking any more venous drainage on cases such as this. So we'll do an angiogram. We'll see what's open, we'll try to leave what's open and not interfere with collateral flow. Which is important here's the vein a little bay. So we don't wanna interfere with that when we remove tumor like this. And for time I'll move on, but basically we'll remove this tumor was involving the scalp as well. So we'll do an aggressive resection. I think we'll move on. And can we just run this one a little bit? This is a, I think a very treacherous area, and this is the falcotentorial region because it's confluence of vein is drainage, internal cerebral veins, basal veins of Rosenthal, straight sinus, vein of Galen, inferior sagittal sinus. And these tumors are very, very treacherous. This is a gentleman who had very little symptoms, but had progressive symptoms. And you can see what I'm looking at here is the internal cerebral veins. So I can't tell you how important that is, to identify the venous structures. If you can do it with noninvasive energy and that's fine, we did an angiogram on this patient, but you can see the internal cerebral veins here and the straight sinus was still open. So there was some interference of venous flow from the internal several veins to the vein of Galen, but it was still open. So what we'll do here is we'll do an inner hemispheric approach. We'll come on and use the gravity to help us retract the hemisphere on this particular side product septal approach above the torcular and come in and remove this tumor. So this is directly over the sinus. We'll take the tumor or take the bone off over the sinus and then open up inner hemispherically avoiding veins here. And then the whole goal here is to debulk the tumor and not injure the veins distal to the tumor. These tumors often grow in the leafs of the faux. So you open up the leaf of the faux and you can see around tumor here. We're gonna get down to the corpus and we'll open up over the tumor. And debulk the tumor using an ultrasonic aspirator, and then identify the margin of the tumor carefully from the veins. These are these soft cotton noise that we developed many years ago to help with this dissection. Oftentimes the rest of the dura is like a venous lake in these cases because they're using alternative flow patterns through the dura, but what do everything to identify and then protect with these cotton noise we protect the veins once we identify the veins. So we're looking now Contra laterally. So we'll remove the faux and identify the interhemispheric fissure on the other side of the faux, and then come around the tumor and carefully dissect it off, making sure that we don't injure these internal cerebral veins below us. You both, the tumor is completely now disconnected. You can see the tumors, they avascular. Again, use the dissection. I dissect around and I use the cotton noise to protect the brand and the veins. And that way you don't give up any ground. We don't read it, dissect any areas and then keep moving the operation forward. You'll find experienced surgeons, are exceptionally quick with their hands, but every motion is purposeful and there's no re dissecting. So we remove the tumor, I'm cauterizing the margin we've protected the veins. We'll put it some surgeon cell over the exposed brain and close, and you can see on the post-op scan, the tumor has been resected in the veins are preserved here. Thanks, Luke. I just wanna show you and be careful of these veins with the approaches. Here's a case from several years ago, it's spheno petroclival meningioma, older woman who did a combined patrosal approach, an older woman. And you can see what happened is the transfer sinus here was injured with the approach. She was perfect post-op one she's becoming lethargic. The residents put an EVD in because the ventricles were up post-op day two, she's okay. You can see that the sinus has been injured with the approach and in post-op day four, she's got a big vein of Lebay infarct here, hemorrhagic infarction. So she had speech problems and was add speech difficulty was permanent in this case. We did a aggressive resection, we left the tumor within the cavernous sinus, as I've mentioned previously. So what are the risks of losing veins? So this is a very interesting notion and we're using the world academy group to answer these questions. And we published a couple of papers on this now, but I just want you to think about this. And these are the studies, So we've asked the senior cranial surgeons from all over the world that are most experienced with cranial surgery and skull base surgery. What studies do you do to look and evaluate the veins? And you can see some people are still using DSA all the time, but everybody's using MRI and some other venography to look specifically at the veins. What's the safety of taking the superior petrosal vein? Well, it's interesting because it used to be the textbooks that you could take the superior petrosal vein with impunity, but I do not believe that. And I've had complications with doing this. If you ask the most experienced surgeons, they're the most cautious. And here's a case in point, here's a woman that I removed a small petrol clival tumor from. She had some tumor in the cavernous sinus, and it was unremarkable case, the tumor came up beautifully, but I lost the potentials on the left side, on the left brain during the case. And I couldn't figure out why. And then I scanned her postop and you can see she's got venous restriction here throughout the brainstem and into the thalamus on the left side. So very dangerous. And I think what's happening with these cases is you have some venous obstruction already because the tumors have obstructed the cavernous sinus, the inferior sagittal sinus, or inferior patrols sinus, the superior patrols sinus and the outflow through the cavernous sinus. And so if you take the patrol veins in these cases, you're taking even more venous drainage. So what's the risk of sigmoid sinus sacrifice? Again, it depends on the experience of the surgeon, but if you look here from the most experienced surgeons, they're more concerned than the less experienced surgeons are. And the same thing, you'll see that the more experience you have, the more you're concerned about infarction from the veins. And again, this was looked at when we looked at CPA, venous sacrifice and veins in the pineal region. Look at this one is quite dramatic. The more number of operations that you have, there's an estimated risk of death was higher by taking the vein of Galen. So experience tells us, and this is why we don't have level one and level two evidence for any of this stuff. We have to learn from our experience surgeons about the risk of venous sacrifice. And I think all of us, as we get more experienced and older, have greater respect for the veins. In general cerebral veins, the same thing, the more experience you have, the more you're concerned about neurological deficit and death. So we're still learning how aggressive we should be. And I'll wind this up right now, but when the tumors do grow, or if they fail radiation, they become bad actors in this area. Here's an example. These patients are often have cavernous sinus tumors and they're very aggressive. And when they grow, they grow aggressively, when we look at their failure rate. So this is a series of patients that Sam Metty and I had that we treated with radiosurgical failure. And some of these patients can have very late treat radiation failure, 14 years after radiosurgery. So we need to follow these patients in perpetuity. And then if they do fail, you're into a real nightmare situation where the tumor is failing and the paracentral area it's involving the cavernous sinus, the carotid artery. And you're gonna decide, have to decide how aggressive you want to be. This was a middle fossum and NGO failed in the cavernous sinus into the face, into the maxillary sinus in this case. So you're often going to have to use complex cranial base surgical approaches and cranial a facial approaches to resect these, but we've done a number of cavernous sinus resections on these cases with recurrent meningiomas. And I'll show you an example of one such one, but it is an operation that is, has some morbidity and I'll show you this one we had to revascularized them sewing in a softness to M2 bypass here, but then we'll go ahead and use a series of incisions to resect the region of the tumor and you come around it like an oncological resection. So this is a non-functional cavernous sinus. This is an infection, but it shows the anatomy better. You tie off the carotid after you've done your bypass. The patients now living on the bypass, we do a bypass. If they fail the balloon inclusion test, the optic nerve is being transected here. Remember this is a non-functional eye, and then we'll come around across the orbit. You'll see, there's the third nerve in the cistern. And we'll go ahead and resect the posterior aspect of the orbit and come around circumferentially around the cavernous sinus to remove a completely. Amputate the contents of the orbit, and then amputate the petrous apex. Now, we're coming across the petrous apex here and we'll run across the croton and in the petrous apex, which we've already isolated and tied off. And now this is the trickiest part is you open up the tentorium at the medial petrous bone and open up into the posterior fossa and you cut the fifth nerve at the root entry zone, and then come immediately and come around the region up to the pituitary, and then we'll remove the cavernous sinus on block in this case. We're into this Fenway sinus here, we'll take the mucosa out and close this. What I'm not showing you is we did a nasal septal flap from below and then remove the orbital contents. In most cases, we'll remove the eye, the differentiated eye, because it is a source of immunological vision loss in some cases rarely in the other eye. So remove the orbital contents and then close careful of our bypass. And this patient was in hospital for about two or three weeks, if I remember correctly, here's the postoperative scan showing the submandibular bypass. Revascularizing the middle cerebral territory here and the contents of the orbit and the cavernous sinus are removed. So thanks Luke. And lastly, I just wanna give you this last case to think about. So we'll use an algorithm we've published this about when we choose to remove the cavernous sinus, we've done this in many more cases. Now, we've published these and there is a high mortality with this operation, but this is a a difficult situation 'cause these patients have failed all therapy at this point. So in cavernous sinus meningiomas, we're trying to find the best management. I use a more nuanced approach upfront. I do decompression initially. And then if all other treatment fails, then we use aggressive surgical resection. So we lack adequate outcome data in most skull-based surgery. I think these are the big questions that we have yet to define. And I look forward to the next generation. That's helping us get there. So in general, try to be aggressive. Simpson has taught us many years that we need to be aggressive and we need to get the tumor out properly to save the patient morbidity in the long run. And we try to do it as safely as we can without causing new deficit. And finally, I just wanna leave you with this notion because I think it will show you the problem that we've had. And I have a series of these patients now that we have these tumors with tumor that has not been adequately resected initially. So this is WHO grade I meningioma, sphenol orbital, there's periorbital or orbital bone involvement here. And now she's had several surgeries. The tumors now in the orbit, she's lost her vision. The eye doctors have done orbital approaches, but only subtotal approaches. And now she ends up with this, with the tumor now in the cavernous sinus around the carotid artery and threatening the contralateral side. So why don't you show the second video here only. I think Luke, so basically what we're gonna do here is we're gonna do an aggressive surgical resection. I did a balloon inclusion test on this woman and she passed the balloon occlusion test. And so we're just going to tie the carotid off, but this is the problem that you run into in these cases is here's the middle cerebral artery. It's completely stuck to the dura in the M1, M2 segments. So you're gonna have to carefully dissect it off the involved dura, it's parasitizing the dura. And so with microsurgical dissection, we'll clear that off. And then we'll go ahead and remove the tumor. Again, we'll go ahead and do that. Just like I talked about before, we've removed the orbital component already and we'll go ahead and remove this tumor. Let's move on Luke. And so we were able to remove that tumor completely and follow her along, but she's still not out of the woods. We're following her very carefully. So finally, I just want to ask you Aaron, what you would do with this case? So this is a classic case of sort of an undertreated patient with recurrent meningioma. So she's had several surgeries. She's been followed by a system in Washington State and by an insurance system in Washington State. And they've watched this thing grow for about 10 years. And I just want to point this out. So this woman has still has vision in her left eye. She had cranial spinal radiation when she was a child. That's the problem that she has. She's got tumor involving her face here and her cheek. And if you look carefully, her teeth are deformed. You see, this has been growing for so long. Her teeth are deformed and she's got tumor in her nose and in her throat and she's having difficulty breathing. So she's really in a difficult situation. And her most immediate problem is that she's having difficulty breathing. So, what do you think you would do?

- I think I would address what's causing her most of the issues first, and it appears that the obstruction of the nasal cavities and potentially obstruction of the airway is the first problem and most immediate problem solve. We'll try to address that first. It seems to me that there's tumor potentially compressing the nasal pathway. So maybe an endonasal approach initially to see how much of the tumor you can decompress first would be the most reasonable approach. I think this is not gonna be something that you can just get through the trans nasal approach. So it's something that may require a trance nasal or potentially to see how much you can get and then go from there initially. As you see, you have that line of the heart palate and the tumor goes below that for the fair amount. So I'm just curious, maybe a trancenasal approach phase first, and then you may have to do a transoral approach at the same time if you cannot get the majority of what you're seeing through the transnasal approach and what was your plan Bill?

- Yeah, so we've actually done the first stage on her. We didn't do the second stage of this week, but so her immediate problem is, as you said, is that she's having difficulty with her airway, right? She can't breathe either through her mouth or nose. And so we did a transfacial approach approach initially. And what we did is we took out the tumor here and the cheek, and we've taken out this tumor here and we've decompressed her. And then we've removed all the tumor nose. We did an endoscopically this part, and then we did transoral as well, because you're limited by the pallet as to how far you can go and fearless. And the way you look at that, is think about where the bone is, where the nasal septum or the nasal bones, right there, sort of draw a line and you can see that we're not gonna be able to, could see this part of the tumor down there. So what we did is we did a transfer, we split the pallet, we came in transorally. She had a tray to start with and at the very beginning of the operation, and then we removed the transnasal and we've removed all this and this, and then the cheek tumor. But what we've still got left is this part below the product involving probably the facial nerve and all the orbital tumor. And so I'm gonna remove the oral tumor this week through a front or temporal approach, and then extend the incision down laterally here and then get the parotid tumor at the same time and dissect it out. But this is a classic case of, this woman has been followed and this tumor is just became completely unmanageable and was sent down to us, but probably should have had more aggressive surgery at the very beginning. This is WHO Grade I meningioma. She's had a several September total resections in the past, And this is the problem, if you get behind on these tumors, just like the last case I showed you, they can become monsters. And then you really have to fight fire with fire in my mind.

- Yeah. I think this really encapsulates very nicely what you said, and that's the statement that the first chance is the best chance at cure. And you really have to keep that in mind. There is a very fine balance, just like anything in life moderation is the key. It too much surgery is not good, too little surgery is also not good. So you really have to learn how much surgery you have to implement as a surgeon. And that's required so much experience as we mature in life. So I think really the first chance is the best chance at cure where the planes are clean, where the tumor is more confined, the arachnoid membranes are more intact and protect you, I guess, injuring any vital structures.

- Yeah, exactly. And I think that the problem that I see is the area of the orbit, I think is the most problematic area for me where this happens, because oftentimes it's a bit of a no man's land. When the tumor gets in the orbit, then the ophthalmologists get involved and this is a neurosurgical disease. And then they end up with residual that recurs into the orbit and then back to the cavernous sinus. And then you're really behind the eighth ball about how you're gonna deal with it.

- I agree it all through the plastic or the ophthalmologist, this is not part of their training or armamentarium to deal with problems such as these. So although they're very much vital in managing these tumors together as part of our team, it behooves us and really is upon us to be able to direct them about the importance of aggressive resection and really doing the right thing the first time don't you agree.

- Absolutely. I mean I think I really encourage the young neurosurgeons to understand the orbit. Don't be intimidated by the orbit. It's very forgiving structure. You've got periodontal fat, that's a great buffer to the optic nerve and the globe. And, and you can chase the tumor, the neurosurgical disease into the orbit, and then deal with it. Use your oculoplastic surgeon as your partner, but work on these tumors together and get them a properly. So you can avoid this long-term problem 'cause this type of patient she's so young and she's really in difficult situation, it's heartbreaking for me to see these types of things that have occurred. It's like watching a wreck and slow motion over time.

- I agree with you really incredible set of videos Bill. Just a new level of mastery in resections of this tumor. It just so enjoyable to watch really it's art. It's truly an art and there is no financial return. There's nothing besides really the passion for technical excellence for taking things to a new level that really requires and demonstrates this level of masters. I really, really wanna thank you. So Luke, we can go to outside the slides. And so there is a few things I wanted to mention, as you were talking today, I really went ahead and brought there Al-Mefty book. I'm sure you know much about that. Here's his book, and it's such a sort of valuable book. I spend a year with Al-Mefty. He's such a master surgeon and he has 23 rules of meningioma resection. And you refer to all of them beautifully. And he says, "listen to me, remove bone and leave the brain alone. Obviously judiciously, I recommend membrane is your best ally. Always do your dissection within the plains. Microsurgical technique is indispensable master it. Sharp dissection is the safest section, never pull on or force anything gentle brother gentle the anatomy of the skull base east complex learning in laboratory seek dura removal with zeal during the first operation. Just like you mentioned, it is the best chance for cure. The best time is the first time. The use of power drill is in this set indispensable practice it be a vascular surgeon, preserve repair or reconstruct vessels life and function run through them. Veins are more vital than usually believed to be preserved them. Preserving perforators is the greatest technical challenge is crucial for preserving function, maintain normal super perfusion pressure, by avoiding hypotension. Plan the closure before the opening. Repair defects with vascularized tissue. A tumor destroys normal anatomy, always be on the lookout for display structure. It is better to save varied is and be wrong a hundred times then to say there he was and be right once. Preservation is the best means of reconstruction. Save every structure, learn from others. It saves you a lot of grief. The little details to the tales of the last skin suture or are what make the difference. Postoperative care is part of the operation is equal to find surgical technique, eliminate intraoperative surprises, extensively extract all information for preoperative studies in intraoperative monitoring is invaluable. Use it. The success of surgery is very intertwined with flawless administration of anesthesia team up with anesthesiologist and above all else to patients' wellbeing is your duty. It requires your full commitment without distraction". So beautifully said so nicely demonstrated by every one of your videos. As the last question I want to ask you, what kind of monitoring do you typically use Bill?

- So we use every craniotomy on our service gets a motor evoked potentials and as matter of sensory evoked potentials, and then we'll use cranial nerve monitoring as needed. So we'll monitor six, three. We used to do visual evoked potentials all the time, but we've stopped doing that, because they're unpredictable for me. And there's, they're so technical dependent, although we're very interested in trying new devices and we've tried all the new monitoring. So we obviously the oculomotor motor nerves, three, six, we don't bother with four, seven, eight, and then nine, 10, 11, and 12. And I really I'm most nervous about nine, 10, 11, obviously not so much 11, but nine and 10. And we monitor those with our special, a endotracheal tube. All the other ones are EMG electrodes and there simple ones to put in. And I think those are the most main ones that we use. The other thing that I would like to mention, and it didn't demonstrate it. I think in some of the videos that I've cut off, but I use papaverin all the time and I use a dilute solution of a papaverin. So we cut the papaverin that comes in the bottle one to 10. So nine, basically nine CCs or 10 CCs with one CC of the concentrate solution. And the reason I use a dilute, is because I had a couple of cases where I lost the auditory brainstem responses when I put it on. And so I don't use the full strength stuff. I use it to loot and I'd let it dwell. So I fill the cisterns and I let it do well. And it is remarkable at counteracting manipulation do spasm. And then post-operatively, it's like for bypasses and for extensive skull based approaches and aneurysms, I keep the patient hydrated. We keep specific blood pressure monitoring parameters based on what their premorbid blood pressure is. And we marked them carefully for a day or two like for my bypass, I keep the monitor for a couple of days in the ICU. And as you said, Aaron, that you're only as good as your weakest link. And I can't emphasize that enough. I'm obsessive about that with the residents and the fellows. They all know that, but we follow these patients like a hawk will. You you're really only as good as your weakest link. So your ICU team has to be on board. You have to be understand what you're trying to achieve, but be important with perfusion in skull-based surgery, because we do so much vessel manipulation, keep the patient hydrated, keep the blood pressure up, watch them carefully. If I mess with the blood vessels or the veins, or if I repair veins or if I repair a blood vessel or do a bypass, I have the patient on aspirin. If it's inadvertent injury, I give them rectal aspirin, 600 rectal aspirin suppository immediately on the table. And then I follow up post-op if I do bypasses I often give them a shot of heparin on the table 3000 or 5,000, depending on the size of the patient, and then have them on aspirin if it's applied bypass. So those are the kinds of things that we do try and reduce vascular injury, which is inherent part. And I like to emphasize that you really need to be a vascular surgeon. If you're going to be a contemporary skull-based surgeon, you have to be able to repair vessels. You have to be able to replace them. You have to do bypasses. And so I think it's they're like collision tumors, these fields and the skillsets completely overlap.

- Very well said. I think what you mentioned about the weakest link is so critical. I also, when I operate, when I think the intense light of the microscope doesn't get enough attention about how problematic it is. If you put your finger under the light for a few minutes, it starts burning. And so what I pay a lot of attention to, is minimizing any direct light on critical structures like the, eighth nerve, I typically hardly ever leave it alone and not cover it with a piece of gel foam soaked in papaverin and just let it sit there. So the lights doesn't even touch it, because these nerves have microvasculature. And as you know, long skull-based surgery to intense slide on the microscope can really burn these vessels and cause spasm of this section and destruction of the nervous structures. I also completely agree in papaverin. In fact, I irrigates every 30 minutes on the operative field and also at the end of the surgery we irrigate with papaverin in close. So essentially there's gonna be papaverin post operatively in the CSF, just bathing everything hopefully for a few days. And absolutely critical information is paying attention to perfusion after surgery. These are details that just don't get enough attention because again, as surgeons we're so unfortunately at times having narrow our point of view or a blindfolds on where our focus is, so, or bandwidth of our processor is so tied up with what we think is important that we miss some of the most critical aspects of postoperative care, which are critical for postoperative outcomes. So Bill, I can't thank you enough for being such a great mentor for me for so many of us, for how selflessly, you have done so much for academic neurosurgery. So it is really an incredible legacy you have created with your career that so many of us aspire to have as well. Do you have any other closing statements?

- No, I just, I just wanted to follow up on the comment that you made about heat, which I think is an under represented problem. And I will tell you about some personal anecdotes with this. You have to be careful with the endoscope. You really have to be careful that tip of the endoscope gets hot. There's been a couple of studies done. They're excellent. And I reviewed them before they were published that they actually measured the temperature in the nose and sphenol they put a temperature probe while they were doing a pituitary resection and it gets hot and it gets, above 40 degrees and that type of thing. And if you've got your suction in your irrigation, that's fine, but I've had a couple of cases. I must admit trans nasal stuff where I've done big pituitary tumors and I didn't touch the optic nerve. So I know that that they were fine and I had some visual deterioration in one patient that was quite severe. And I think it was probably heat from the endoscope and drawing out and just be cognizant of that because the endoscope is very hot, even lighter than microscope, as you mentioned, but the endoscope is really a dangerous tip to leave in one place without irrigation or suction going on. Thank you.

- Yeah, you're welcome. And I say my last comment here is that be very judicious use of radical skull-based osteotomies. I think with, with, as I get older, I find that I can do more with a more restricted exposures. So we've become very much conservative with the use of petrosal approaches. You can do so much more through the supermietal thrilling that you showed in the young gymnast. You really can do so much more through that and a beautiful operation with minimizing the length of the surgery. Because I think the length of the surgery, the anesthesia, the destruction of normal anatomy has so much to do with the recovery. I think just like anything else in the history of mankind, everything comes in waves, the skull base surgery and the radical approaches became very popular in late 80s and 90s and 2000s. And then sorta, now we're becoming more balanced in terms of what skull base surgery means. It's really a tough balance. One has to be very careful about.

- Yeah, I think we all become more circumspect as we get older.

- I agree with you. So again, Bill cannot thank you enough. Obviously we'll be inviting you soon as one of them are very much, most frequently requested speakers for very good reason. Thank you.

- Thank you, Aaron. Again, I wanna thank you so much for being here. It's really an honor.

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