Relevance of Skull Base Surgery to Pediatric Neurosurgery: Pediatric...

Right. Welcome back to the Global cast. Um, I'm delighted to carry on the conversation about endoscopic skull-based surgery. I feel like I had the perfect lead-in, um, from the talk that Doctor Schwartz presented in which he beautifully laid out all of the varied approaches, um, and some of the pathologies that we see in the pediatric population. What I hope to accomplish with my talk here is give the pediatric perspective, um, to complement Dr. Schwartz's talk and focus on a couple of things, um, throughout the next 20 or 30 minutes. Um, one is something that Dr. Schwartz touched on already, and that is the importance of teamwork, and Uh, collaborating with, uh, experts at your institution to, um, define a real interdisciplinary, uh, area of expertise, um, to approach these really challenging lesions. The second is to really think about the anatomy, and again, that dovetails nicely with what Doctor Schwartz laid out already about thinking about the age-dependent variation that we see in the skull base. The third thing that we should think about are the goals of the surgeries. The goal of surgery in the pediatric population is sometimes very different than it is in the adult population, whereas sometimes gross total resection is the goal in an adult. Sometimes a biopsy followed by radiation is the, uh, is the algorithm or paradigm that we're aiming for in craniopharyngioma. Those are important to think about. And the last is creativity, and Doctor Schwartz already highlighted some of the really interesting cases that we've attacked utilizing endoscopic approaches. So really the only limits um are the putting together of a team uh and thinking creatively about how to utilize all of the tools and techniques that we have at our disposal. So, the continuum, excuse me, the continuum of endoscopy, age-specific considerations, categorizing the pathology. I'm gonna pay a little bit more attention to the craniocervical junction. Ted outlined a little bit that we've um developed an expertise at approaching the odontoid, um, in patients with craniocervical junction abnormalities, and I'll spend a little bit of time on that and then talk a little bit about some of those unique pathologies and creative approaches. So with respect to the continuum of, of minimally invasive neurosurgery, I like to think of it as essentially a spectrum. And um no one will define themselves as a skull-based endoscopic surgeon entirely. It has to be uh within the context of understanding when you need to use purely intraventricular approaches uh and when endoscopic approaches are necessary, um, and then the endoscopic endonasal approaches fall in between. And the way you categorize those things is by looking at not only the pathologies, tumors, congenital abnormalities, and trauma. But also these questions, what's the anatomy? What's the demographic that you're talking about? Again, what's the treatment paradigm? What's the intended goal of uh the surgery? For growth in that area, depending on the age. So as an example, just to give you both ends of the spectrum before we dive into the transnasal approach, the classic intraventricular endoscopy, which you'll hear a lot about later on, has some limitations, right, you're in a fluid medium. Um, there's, uh, certainly subpar optics compared to an air medium, uh, and issues with hemorrhage or something that we're all familiar with where a little bit of blood can obscure the view. These are used for things like biopsies, fenestrations, CSF, um, management for, um, intraventricular anatomy. This, for example, Here is an intraventricular cyst associated with the craniopharyngioma. You can see quite clearly optics are nowhere near as beautiful as those that Doctor Schwartz showed in his last talk. You're working through an air, you're working through a fluid medium instead of an air medium. You can see blood and pertinaceous debris floating around. Um, and in even the best case scenario, you're never going to approach the same degree of optics. But in a case where the goal is essentially opening up a cyst to allow decompression of the third ventricle to follow with stereotactic fractionated radiation. Um, certainly this is a, an optimal approach and something that we use frequently as an adjunct, um, to the, uh, transnasal endoscopic approaches. On the other end of the continuum is the classic endoscopic assisted approaches, right? So these are now in an air medium. You have much better optics. Um, you have the ability to do bimanual, uh, uh, manipulation of tissues. You can see here on an anterior lobe arachnoid cyst, the ability to use the suction as a traction device so that the scissors can be used in a much more elegant fashion to create that fenestration, something you would never be able to do quite as nicely utilizing the fluid medium of a traditional endoscope. So those are the two sides of the spectrum, and I feel like endonasal endoscopic surgery falls somewhere in between. You can't forget that sometimes, just because you have a tool, it's not necessarily the right one. And there are examples like this of cranioppharyngioma that you simply just need to utilize your old skills, do large craniotomies, and do the right approach, uh, regardless of those tools that you have in your armamentarium. So to go back to the categorization of these different pathologies, something that Ted alluded to um in the first talk, we try to categorize all the pediatric lesions that we've seen in our last decade of operating together. And, and we came up with these four categories that I think are a nice way to essentially silo them and think about them, um, uh, independently of one another. So we think of them as benign neoplastic lesions, malignant neoplastic lesions, congenital malformations, and then diatrogenic or traumatic defects. They somewhat correspond to different areas and different approaches of the skull base, but they're interchangeable to some degree. Again, Doctor Schwartz went really nicely through all of this, and I'll just highlight just these five points that I think about when, when approaching an endoscopic case in a child. The nasal aperture does have to be thought about. Uh, using bimanual um operation can sometimes be challenging through very small nasal apertures, and the scope, and the scope holder can get in the way. So you have to be aware of that. The pneumatization was addressed in the last talk, as well as issues with skull maturation, the interotid distance, and the closure of the defect. We didn't really talk too much about that in the last case, but we haven't had much issues dealing with um creating nasal septal flaps in the pediatric population. The history of this is important to talk about. There are a lot of other really um fantastic groups around the country and around the world that are pioneering this technique and are learning along with us. The Italian groups, the group in Pittsburgh, for example, um, were really the ones that were leading the way 10 and 15 years ago. These are some papers that we've published looking at the anatomy and the different approaches to the skull base, uh, and adding our, uh, case series, um, and experience to that, that literature has been, uh, helpful. The goals of surgery are something that I told you at the beginning, I thought were really important for us to discuss with respect to a pediatric population. Sometimes there are different goals of surgery. There's different pathology. Again, Doctor Schwartz highlighted that the pathology of craniopharyngioma in children is very different molecularly and genetically than it is in adults. Sometimes the role of biopsy and decompression is different, uh, and navigating around these, uh, growth centers is really important to think about. And you'll notice from our uh results from one of our recent papers, the goal of surgery, this is not something that you see in a lot of, excuse me, in a lot of adult papers. The goal of surgery sometimes is a biopsy or a subtotal resection. And so, Quoting rates of complete resection or gross total resection are not really as important in these populations as they might be in adult literature, where sometimes the goal here really is decompression, preservation of function, and allowing the child to develop normally for another period of time before other therapy is instituted. With respect to the carrier's approaches, this, um, harkens back to what Doctor Schwartz talked about and gives us a good framework upon which to build some of our, uh, cases that we're gonna talk about here. He talked, uh, extensively about cranialphharangioma, which I won't talk about. Um, instead, I'll jump over to the transclival transodontoid approach and focus a little bit more on this pathology here. This has been, um, uh, a very interesting transition. I'm sorry, my slides are advancing there. A very interesting transition from, um, what was traditionally a trans-oral approach, um, over the past several decades to what is exclusively now an endoscopic endonasal approach, uh, in our practice. Um, Doctor Schwartz and, uh, his adult team also published some of the advantages, including the ability to extubate early and begin feeding early. And we've seen the same exact results in our pediatric populations here. These are almost always done in conjunction with um posterior fossa decompression and cervical instrumentation, uh, because of the instability uh that ensues from uh odontoid resection, uh, and is done very, very easily without any entering of the sinuses, um, as Doctor Schwartz highlighted before. I'm gonna go through um a case here, um, just to sort of the anatomy. Um, it's about a minute-long video, we'll try to run through this here. This is the retropharyngeal fascia that we're looking at here, and we make a linear incision. When we first started out, we, we used the U-shaped incision and we found that the linear incision works well, as long as you utilize this technique where you're able to retract the uh contralateral soft tissue utilizing the suction. So the suction is really an important tool here where you're using it to retract the tissue, suction blood, and also suction the smoke. We use live uh brain lab continually to give us guidance. The anatomy is not always intuitive here. We essentially drill down the inferior aspect of the odontoid bone with the diamond drill until we find a nice interface between uh the base of the resection and the, and the dura. You can see a nice shiny dura there and we're using standard uh kerosene punches to open that up. And then we began working up. In this case, we really needed to resect some of the clius where the compression of the brain stem was significant. And so, So delineating that plane between the clavus there with the straight curette, pulling down some of the inflammatory soft tissue, and utilizing drills, curettes, and kerosons again to achieve that degree of decompression uh necessary. At the end, the closure is really quite simple. We use a little flow seal in the cavity and then re-approximate the retropharyngeal fascia utilizing um one or two single uh interrupted stitches um that um can be slightly challenging to place, but, uh, that we found, uh, fairly straightforward utilizing a single uh nasal approach with uh either a permanent or absorbable stitch, and that's highlighted here. Here's some examples of um what the pathology looks like and why we feel like it's important sometimes to incorporate the uh endoscopic, sorry, this is again advancing, the endoscopic endonasal approach preoperatively, you can see a significant laybasia and retroflection of the odontoid with severe brain stem compression in the child who was severely myelopathic and and dysphasic. And um the postoperative results showing uh restoration of CSF flow in front of and behind the brain stem, uh, and restoration of that normal anatomy of the medulla. Here's another case, uh, an eight year old female with severe brain stem compression, scoliosis, and sleep apnea who underwent the same procedure. And again, you can see a dramatic restoration of that, uh, loss of the angulation of the brain stem and restoration of flow, uh, in front of the brainstem. Some pearls that I wanted to share that we've learned over time from uh the odontoid resections. We don't always use this uh intraoperative CT scan. It's a nice, um, thing to have in the operating room to fall back on. Um, we've done 4 or 5 cases and, and it provides, um, some guidance for us. But the important thing is to have navigation. Uh, pre-op CTA or MRA is sometimes a part of our workup so that we can really identify and navigate the carotid arteries and know where they are at all times during the case. Um. Defining the anatomy continually throughout the case, finding the lateral edges of the dens and the superior aspect of the dens is sometimes not as intuitive as it seems, uh, with all the soft tissue and inflammatory tissue around there. Um, what we found is that we'll often leave the very tip of the odontoid or the left side of the dens, um, for a right-handed surgeon coming from the right nare. You have to be careful about getting over to the opposite contralateral side. Uh, and so we're really conscious about that and defining that anatomy early in the case now. Our experience of 10 patients now, we have 7 here from our last publication, we're up to 10. Um, a couple of things to highlight here. One is the early extubation. So they're all getting extubated, uh, on day of life 0 or 1. early on, we kept them intubated out of safety, but now we're trying to extubate them all on the same day of surgery. We had one early reintubation that was due to aspiration of a sealant, which we no longer use. It was a little bit redundant and unnecessary, uh, due to the lack of a CSF leak. Um, and, uh, this highlights really nicely how easy it is for these children to recover, get extubated, and begin eating. This shows you a little bit of the anatomy that we're dealing with. Um, you know, this is a very, very select population of children. This is not a typical KI population, but children who have liboaxial angles approximating 100 degrees and Grab oaks angles, uh, Grab Oaks measurements, uh, in the 10 to 15 or even larger, sometimes millimeter range. These are significant patients with significant compression and torque on their brain stem. Uh, Dr. Schwartz talked about the, uh, JNA, so I won't go through that at all. This is the transmaxillary transterogoidal approach. CSF leaks are something that we also see infrequently. Again, it's adaptation of essentially techniques that have been perfected in the adult population and using them in the pediatric population in the exact same way. Um, Doctor Schwartz did mention this case. I just wanted to show you, um, some of the video of it, um, since, uh, he didn't get to the video part of this. This is the, the ventral appendymoma, uh, that we were talking about and some of the creativity that you need to sort of think about doing these cases, um, when they present themselves to you. This was. The ependymoma that was uh really approximating the clivius which was significantly eroded down, uh, and we had beautiful um access to it. So this is essentially the same exact, um, approach going straight through the clivius using uh diamond drill bits and kerosene punches to access that dura. Um, obviously really important to think about and localize the basilar artery and any branches preoperatively utilizing both imaging and then intraoperatively with your, uh, Doppler probe, opening up the dura, um. Separating out that uh industrial layer of the dura and finding the tumor. This is the beginning of the resection where a biopsy was performed. Getting straight into the tumor. There was uh no normal tissue in front of us here. So it's essentially coring out a tumor, very analogous to taking out a large macroadenoma using ring curette's, um, biopsy forceps, uh, and then even the Nico aspirator at the end, uh, to drill out some of it. And I'll show you the resection cavity here at the end. Quite a nice cavity, um, and again, a near total, but not gross total resection for this child, um, and did extend his life, uh, more than a year, even though we knew this was a palliative procedure. So thinking about some of the things that are um uh themes that run through all of the different cases, the development of the pediatric skull base is really important to think about as a continuous and asymmetric event. You have to think about each child and look at their films in an individualized fashion and devise that treatment plan based on the pathology, their age of development, uh, and also the treatment algorithm that you're, um, thinking about with respect to adjuvant. Therapies and their growth. Really think about the radio anatomical considerations. Spend a lot of time studying the films, make those measurements. Think about the low end of the um resection that you'll be able to achieve on a joint resection. Think about the width between the carotid arteries when you're approaching a, a resection in a small child. Um, these considerations are really important. Think about image guidance, um, and, um, really plan ahead of time with your, um, ENT and how you're going to do vascularized flaps in the, in the young children where the anatomy might be a little bit unfamiliar to them. Um, in the end, a careful selection of these balanced and experienced teams is really the most important thing. I know Doctor Schwartz mentioned it. I'll harken back to that again. I think if you can find a, a pairing of an adult and endoscopic surgeon, an ENT surgeon who's invested in this case, then you're gonna find that the collaborative, uh, atmosphere in terms of preoperative planning and intraoperative decision making goes a lot further than you might think it, it is necessary. And why we do that. This is the child that uh Doctor Schwartz mentioned with the uh orbital rhabdomyosarcoma. It's a child that essentially was given no other options and would have been uh incurable. Uh, and, uh, here's a video of her now several years out from her resection. And this essentially is why we do this type of surgery, um, through the skull base. Um, I'd like to thank everyone who's out there and, uh, uh, watching us for your attention. I do want to mention that there's some information at the bottom of the screen if you want to look at it later, um, to get more information about these talks or get access to some of these talks. Uh, Doctor Schwartz and I also, um, uh, both, uh, presented a course, uh, annually. In New York City, if anyone is interested in attending that course, and, um, Doctor Sweden and Doctor Schwartz have fellowships available uh for skull-base, um, uh, expertise, um, so all those things are located on the bottom of the slide as well. So again, I'll be happy to answer some questions in the audience, as well the rest of the panel. Thank you very much. Thank you, Doctor Greenfield. That was a wonderful talk and um definitely highlights the importance of the collaborative nature of pediatric and adult endonasal uh skull-based surgery. Um, one of the questions that I had for you, um, is for cases of the posterior fossa, uh, where you know you have to do instrumentation fusion. Some of these kids have instability, some of them have, uh, uh, pre-morbid conditions that, that make them more susceptible. Are there any tips for positioning a young child, um, in the midst of a, of a fusion? Are there timing issues for how, when to do the resection versus the fusion? Um, can you speak to, speak to that at all? Yeah, that's a, that's a wonderful question and insightful, and it's insightful because we've actually changed our algorithm slightly over the past decade. Um, we used to be, uh, quite worried about, um, the additive morbidity of doing these cases together. Um, and so the idea of doing a, um, stage procedure, meaning that we would do instrumentation and decompression, uh, for example, on a Monday. Um, and then give them a couple of days to recover and then do the second part of the surgery, um, on a Wednesday, the endoscopic endon nasal part. We then went to a one-day procedure trying to, um, eliminate the, um, multiple intubation extavation trials. It turns out that it's probably better to do it as a staged procedure. Um, it's simpler for the child to do it once, but in terms of the amount of, um, equipment needed for both of those procedures, the flow in the operating room, it ends up being a 10 to 12 hour day. Um, and no one's happy, you know, doing that type of delicate surgery at the end of a long day. And so we split them up now and, and, um, extubate them in between. Another question I had that maybe both for Doctor Schwartz and for Doctor Greenfield, um, and you mentioned the, the size of the nare and obviously when you're talking about pediatrics and uh all kinds of head shape sizes and, and facial sizes, do you ever incorporate a sublabial approach to the sphenoid sinus? And if you do, are there any pearls or tips that you wanna give us for our uh endoscopic use for that? I, I don't believe we have done it in any of the children thus far. I think that, um, it's a matter of getting accustomed to the instrumentation and the, and the limitations in, um, the hand movements that you need to perform. Um, when the residents try and get their hands in there with the scope and two instruments, you can see how difficult it is to sort of feel yourself around and, and it, it takes a good deal of essentially ergonomics, setting up the scope in the right place, pulling it up and lateral and out of the way so that you can get two instruments in there. Um, but we haven't had to incorporate that yet, um, but there is a pretty steep learning curve in terms of the really young children because it can be just technically challenging and ergonomically frustrating to get those instruments working together in, in the tight spaces. Another question, Jeff, uh, we, we've spent a lot of time talking about the, the pediatric specific skull base issues, the dynamic growth, the pneumatization of the sinuses. Is the equipment different in a five year old versus a fifteen-year-old, and you do, do you use different calibers, scopes, dimensions of instruments? What, what changes along that continuum, if anything? Do you wanna answer? Yeah, I mean, the truth is very little, you know, because, you know, endonasal equipment and scopes are designed to work in a very small space, um, they work well in a very small space, and the pediatric nose, as, as we discussed earlier, certainly is smaller, but there's adequate room to do the case, you know, is it a little tighter? It's a little tighter, but is it so tight that you can't do it? No, it's not. So the instruments are actually very well designed specifically for that. We've never had to kind of say, well, we can't use this instrument because of the nose is so small. One other thing I want to highlight along those lines is the, the fact that as endoscopy and neurosurgery has flourished, uh, application specific equipment and scope technology has kind of met those demands. So what these experts are talking about with regard to skull base, uh, really it's an armamentarium that is distinctly different than what you're going to hear about forthcoming with regard to intraventricular work. And endoscopic assisted. So in, in a large repertoire, uh, there are numerous cases that, that define, uh, really the, the type of technology that you'll be utilizing, and it gets a little overwhelming, but as, as the indications have expanded, so has the instrumentation. So one size does not fit all in endoscopy, as you, as you'll hear. That was a wonderful wrap up to skull-based endoscopic surgery, especially when you're talking about pediatrics and The Limitations that I'm sure most of us have felt, uh, over the years, um, hopefully as, as we grow in the field, we have more and more trainees coming out of programs like yours. We'll be able to expand and keep moving forward and, and doing this kind of surgery for kids. Uh, you can definitely tell the, the difference in their, um, post-op recovery. I'm sure the, the quickness with which they leave the hospital, um, the, the lack of deficits they have from the brain damage you mentioned. Um, I think it's, it's all really a, a wonderful, um. Uh, increase in, in our abilities to do surgery minimally basically. So thank you very much for the wonderful talks. Thanks for having us. I think we can go on to the next talk if that's OK. Um.