Pediatric Endonasal Skull Base Surgery: Pediatric Endoscopic Neurosurgery 2018

Terrific. So, um, I'm gonna be talking about um an overview really of pediatric endoscopic skull-based surgery. And it was really an offshoot of the adult program here. Um, but it's been a very, very fertile collaboration that I've had with Doctor Swayan and Doctor Greenfield. And, uh, I wanna take this opportunity to kinda outline some of the things that can be accomplished with these approaches. And then I'm gonna pass on the baton to Doctor Greenfield to elaborate on some specific approaches. Um, that I'm gonna not talk about. Um, let me see if I can advance my slides. Let me just use this button. So, the first thing I wanna talk about is collaboration and the importance of collaboration because while endoscopic skull-based surgery has evolved as an adult specialty, um, it was a little bit slow in propagating into the pediatric world. And we've been, uh, working hard to try to aid in that propagation. Um, one of the reasons is that, um, You know, many pediatric neurosurgeons felt that maybe there wasn't enough room. They hadn't had enough training in endoscopic skull-based techniques. And so, what I think made our program successful and other programs successful is really a strong collaboration. And I encourage anyone who's interested in this to try to form a collaboration between pediatric neurosurgery and adult. Uh, endoscopic skull-based surgery because, you know, as I learned, you know, children are not just little adults. There's a lot of unique special things about the pediatric population that I certainly was not, uh, aware of and able to, to manage as well as a pediatric neurosurgeon. And on the other hand, the pediatric neurosurgeons don't always have the expertise, uh, and the experience doing as many endoscopic skull-based cases. So, having a strong collaboration between the two programs, I think is the key to success. Um, and there really are, uh, numerous and innumerable amounts of, uh, pathology that can be tackled, uh, using endonasal endoscopic techniques. So, we've, um, Try to, uh, propagate the techniques first by putting out this silver book, um, that, uh, uh, Stortz helped us put out, um, which is available, uh, online. We also have a textbook that's coming out, uh, shortly, uh, by Tima that will, uh, go over some of the endoscopic skull-based techniques specifically for pediatrics. And I'm gonna go over a lot of those different techniques. We first started looking Um, through, uh, some papers that we published on how does the skull base develop and how big are the corridors that we're able to work through. Uh, and I'm gonna give you a little bit of overview on that. But as you can imagine, you know, as the pediatric skull base develops, there are many forces that change the size and the shape and the morphology of different structures in the nose. And we did a radiographic study where we actually went through all of those different parameters that we thought were important to see how they evolved over time. Obviously, one of the biggest ones is the uh pneumonization of the sphenoid, um, and the distance between the carotid arteries, because the main corridor that we work through is the sphenoid sinus, and having adequate room is uh incredibly important. So, we actually measured on a, a number of uh normal MRI scans, the size of these different uh parameters, the height of the sphenoid, the width of the sphenoid, the length of the sphenoid sinus to make sure and to figure out if there was a threshold before which and after which we may have an easier or harder time. And as you can imagine, there's a graded increase in all of these parameters over time. But what was interesting to us was to see that there wasn't sort of one moment in Time after which we can or we can't do these procedures. And it's a slow propagation over time of growth. Um, in general, we felt very comfortable, uh, with an age of 4 and above as an age after which we find that we can really do most procedures. Um, it is possible to do it younger. But I think that's been sort of a lower limit age at the age at which we've been very comfortable uh proceeding with endonasal surgery. Um, the sphenoid sinus progressively, uh, pneumatizes both, you know, in the sort of rostral caudal dimension as, as well as laterally and down into the sphenoid. And these are just graphs of the different types of pneumatization. For the most part, in the pediatric population, we tend to see the console type of sphenoid sinus, and over time, this does enlarge. Um, some of them are precellar as as well. It is rare to get a full cellar or retrocellar, uh, pneumonization. But what we found is important, I'll show a little bit more data on this, is that even when you have a conralled sphenoid sinus, uh, much of the bone is very, very soft in the middle of the sphenoid, and it's very easy to drill it out with a diamond drill and create a pneumatized sphenoid sinus for yourself, uh, to make the surgery much easier. Um, this is just a, a graph showing at different ages, how the sphenoid does pneumatize, showing you that, you know, really after age 4, you get rid of most of those control sphenoid sinuses. Now, that's, that's the gray bar from age 2 to 4. And after age 4, that really goes away. Um, the inter carotid distance similarly does increase, but as you can see, it doesn't dramatically increase. So at age 15, sorry, at age, uh, yeah, at age 15, it's about 15 millimeters. Um, but at age 5, it's still 1213 millimeters. So that extra 2 or 3 millimeters doesn't make a dramatic difference to the surgeries that we're doing. This is the setup that we use at Cornell. I know it's a little different than some other places. We tend to work with a scope holder. Uh, we have surgeons on either side of each other. We have screens on either side and we put the navigation in the middle. Um, everyone does it differently. This is just our workflow that we find works for us. So, I'm gonna go over quickly each of the different approaches uh that we like to use in different places we can get, um, using what we call the transnasal or transfrontal approach, we can, that, and the reason we call it transnasal cause they're all sowhat transnasal is we, we don't have to go through any sort of a, uh, sinus to get there. Without traversing a sinus, you can go up through the cribiform plate. If you're medial to the middle turbinates, you can go straight back through the odontoid and the clivus. Uh, and some examples. Uh, of pathology. The most common, of course, for the cribiform plate would be an encephalocele. And whereas, uh, traditionally, these would be removed with a bronal craniotomy, mobilize the pericranial flap, you essentially do 100% of encephaloceles, uh, using an endonasal approach. Even fairly large encephaloceles will do an endonasal approach. Um, on the bottom, you just see some examples, superior turbinate, middle turbinate, and the encephalocele kind of peeking its way through, through the, through the two. The way we like to do these closures, we give intrathecal fluoresce, we put a lumbar drain in. Uh, some of these, uh, uh, patients have, uh, uh, benign intracranial hypertension. And you have to really resect all of the encephalocele until it's gone. I like to say in the OR we make the leak worse before we make it better. Uh, and we cauterize back the edges of that. Um, you really define the bony edges, and then we like to do an inlay of Dureguard, something that sits on the inside, and then do an onlay of fat and a, a nasal septal flap. Um, for encephaloceles, I do like to leave a lumbar drain in for a couple of days afterwards because some of these patients do have increased intracranial pressure and it allows us to decrease that pressure while the closure is, uh, tightening up. Um, the transclival approach, uh, uh, this is an interesting case we saw of a patient who had a multiply recurrent appendymoma within the pons, within the brain stem. Uh, this was technically a very, very challenging case. It had failed chemotherapy, radiation therapy. But as you can see, the tumor presents itself to the back wall of the sphenoid sinus. This was a patient who was deteriorating neurologically. And we were able to go in endonasally and open up the back of the, of the uh uh sphenoid through the clivus and get right into the ventral pons and actually do a decompression of this tumor. And you can see uh the pre-op films above and the post-op films below. Um, again, this was not uh a gross total resection type of tumor, but a decompressive tumor to allow the patient to recover neurologically in preparation for future adjuvant therapy. Um, the transodontoid approach, I'm gonna leave for Doctor Greenfield, but this, uh, does not have to violate a sinus. Um, and we can easily get to the tip of, uh, C2, uh, particularly in patients who have, um, some basilar invagination. The sphenoid sinus is the main sinus that we use uh to approach the skull base. Um, this is the example I wanted to show that consral sphenoid sinus, we're able to drill out a sphenoid that looks like it's not at all pneumatized. And what you get is this kind of mushy bone, uh, that's uh sort of vascular in the middle. And if you drill out this bone with a diamond drill, you can turn it into A very well aerated sphenoid sinus. So here's the view of the sphenoid and the pathology before we started our drilling, and you can see at the end of our drilling, we actually have quite a large opening. You can create a sphenoid sinus from a sphenoid that's not aerated, and you just drill down until you get to that uh harder. Uh, bone that's still present over the carotid artery, uh, and over the plenum. This is an example of the pre-op film in a patient, a child with a very, very large cranioppharyngioma, uh, very, very small sphenoid, and you can see we're able to access that literally by creating a sphenoid sinus, uh, with a drill. This just shows you that film, very large cranioppharyngioma, not well aerated sphenoid, young child, uh, all supracellar, uh, preoperatively above and postoperatively below. Uh, you can also see in particular that in pediatric patients, we do tend to leave a small rim of tumor on the hypothalamus. We don't want to damage the hypothalamus. We don't wanna cause morbid obesity, cognitive, uh, uh, maldevelopment. Um, and so often that is the goal of care. Uh, this is a, a fascinating case that we saw that I wanted to present, um, and we've given, been given permission to show this, uh, uh, patient's, uh, images. Um, this is a, uh, young girl. You can see her here, uh, at age 9. Uh, on the left. And then at age 11, uh, she's already bigger than her mom 2 years later, and in fact, she had a pituitary tumor, uh, causing gigantism, which is a very, very rare disease, uh, where the tumors, uh, are making growth hormone before the growth plates are closed. She actually underwent Uh, endoscopic, uh, surgery, uh, by a surgeon who maybe wasn't so familiar with some of the extended approaches. You can see the approach here. Uh, the tumor in the cella was removed. There was residual tumor above. This patient was told the rest of the tumor is unresectable and she was incurable, and she came to us for further surgery. Um, and we felt that by doing an extended approach, going through the planum and the tuberculum, we could remove the rest of the tumor. I'm gonna show you a video of that surgery here. You can see it's a re-operation. And we're extending the approach. Uh, above the, uh, pituitary gland, you can see the optic nerve above. We're dissecting the arachnoid, uh, and the tumor just below the optic nerve, uh, cutting, uh, sharply, doing bimanual extracapsular dissection, and we're able to remove that supracellar tumor, and then take additional tumor extending up a bit into the, uh, base of the third ventricle, uh, and then tumor down in the, uh, that's the diaphragmmacella on the very top of the, uh, pituitary gland. Uh, to make sure we get the whole tumor out. We're just looking with a, uh, endoscope, uh, to make sure there's no residual tumor. We do a gasket seal closure with fascilata buttressed with a piece of med pore. Nowadays, we cover that with a nasal septal flap. Uh, and the great news is that this, uh, young girl was then cured of her gigantism, which is actually, uh, fairly challenging to do. And you can see here the medpore buttress and the, uh, tumor that's been removed. Um, this is a patient who had a giant pilocytic astrocytoma. She had a biopsy. Uh, she had radiation therapy, uh, but the tumor continued to enlarge. She had progressive visual loss, and we're able to do an extended endonasal approach, uh, to debulk this tumor. You can see it extended very, very far up into the third ventricle, and here you see the closure with the nasal septal flap and a piece of med pore and the tumor nicely debulked. So, there's a wide variety of applications for this. The transethmoidal approach allows us to get through the ethmoid sinuses into uh either the lateral cavernous sinus or the medial orbit. Um, this is an example of a patient who had a, uh, recurrent rhabdomyer sarcoma, had had two prior surgeries, chemotherapy. The tumor recurred again. Uh, it was actually lateral, uh, to the orbit. Uh, but we felt by opening up the ethmoids widely, we could get through the ethmoids into the lateral orbit to take out this residual tumor. You can see it here pre-op, post-op, uh, pre-op on the left, and post-op on the right. I think I have a video of some of that surgery. So, we're actually working below the orbit. We've opened up the uh ethmoids. This is the orbital apex. So this is the periorbital. The lamina pparracea has been completely removed. And we're, we're now working below, and then we have to go up and around. Uh, one of the keys to doing this type of surgery successfully is having angled in. You can see we have an upgoing pituitary. We have an angled suction. We're using 45 degree uh endoscopes that allows us to look sort of under, out, and around the uh orbital apex to get to the lateral compartment. You can see we're sort of carefully with um angled instruments, uh, dissecting this tumor out from its attachments to the lateral periorbita. Uh, and then removing the rest of the tumor. See if I can go forward. Uh, the transmaxillary approach is another, uh, wonderful corridor we can use, go through the maxillary sinus that allows us to get into the terraopalatine fossa. We can get in the infmporal fossa, the very, very lateral sphenoid, uh, the Petris apex as well. One of the most common pathologies in a child that we use this for are juvenile nasolangio fibromas. Uh, these tumors are very, very vascular. We tend to embolize them beforehand, they still bleed quite a bit. This just shows you an example of a JNA pre-op and post-op. Most of them arise from the PPF, so you have to do a wide exposure of the back wall of the maxillary sinus, and then postoperatively you can see below, the tumor's been completely resected through a purely endonasal endoscopic approach. I want to talk a little bit more about cranioppharyngiomas because as you can see here, they are very common in the pediatric age group. They have really two ages of presentation. Um, in the pediatric group they're mostly adamandenomatous. Uh, we know the genetics of that. They're more likely in the cella, they're more likely calcified. Adults have both adamandenomatous and papillary, and the papillaries with the BRAF mutation are more likely supercellar, less likely calcified. Um, as you know, they can grow down, they can grow up, they can grow in many different directions. Uh, when we approach these from above, we tend to be looking at the optic nerves in the carotid arteries, and this can make the approach very challenging. Uh, whereas, and this is just an example of looking at a cra cranioppharyngioma from above through a teronal craniotomy, showing you that what you see are the optic nerves, the carotid artery, the third nerve, uh, which is why the view from below really is such a great view. You get a better view of the stalk, better view of the 3rd ventricle, better view of the hypothalamus, less retraction on the optic nerves in the brain, that allows us to get a view like this where we can really, really see the pathology from below beautifully. So here's a cellar supracellar craniopharyngioma. These again are more common in the pediatric population that arise from the cella. And here we would do an approach where we open up not just the cella, but we also do a supercellar approach, so we remove bone over the planum and the tuberculum. Again, we're bimanual just through the nostrils. Our scope is fixed on a scope holder. Uh, this is a backbiting kerosene I love to use to remove the plainum because that angle can be sometimes very awkward. We use a Doppler to make sure that we don't get into the carotid artery, and our first goal is to internally decompress the tumor. Uh, we open up the, the dura, uh, above and below the superior cavernous sinus, that's intrathecal fluorescine staining the cerebrospinal fluid. Uh, and we use that to resect the, uh, diaphragm macella. And then we'll internally decompress the tumor. And uh dissect it free. We try to save the pituitary gland as long as we can. This is another maneuver we like. We'll actually remove the bone and the dura together. Here you can see that the chiasm has now been exposed. We know we're not going to do a a tight closure of the dura with sutures, so we just remove the dura with the bone, and then we internally decompress the cranioppharyngioma, dissect it free from the cella, and then follow it up into the supracellar uh cistern. We try to save the stalk as long as we can, but if the stalk is completely infiltrated, we will sacrifice the stalk and opt for a cure. We do try to save the superior hypophyceal arteries because those go superiorly and also feed the chiasm, and that's extremely important. Here you see a bipolar where that's the superior hypophyceal artery feeding the stalk, and the tumor that we have to take, but the branches that go superiorly, we try to save because we don't want to get any visual loss. Let me see if I can forward this. Postoperatively, you see a complete resection of the tumor. One more I'm gonna show you. This is not a fully pneumatized sphenoid, very large supracellar craniopharyngioma filling the third ventricle. Uh, I'll show you how we took that one out. So you see the sphenoid is not fully pneumatized, which means that we do have to drill it quite a bit. Yep, I don't, not sure if this is playing. There we go. So you'll see some extensive drilling to make the sphenoid more pneumatized, which we can do. Um, it's a very large tumor, bigger than our opening. We open up the arachnoid first, and the key to taking out a tumor like this is to first internally decompress the tumor so that we can fold it in upon itself. And then do careful bimanual extracapsular dissection to dissect the tumor off the surrounding structures, such as the PCA, uh, the third nerve, the superior hypophyceal arteries, and of course superiorly the optic chiasm and the floor of the third ventricle. You can see we're dissecting the tumor sharply off the, uh, laterally, here superiorly off the chiasm, using careful bimanual sharp dissection. And then we'll pull the rest of the tumor out of the 3rd ventricle. Here's the stalk, we're actually trying to save the stock as best we can, uh, hoping that it will work, and we only take the stock if it's completely infiltrated with tumor. In the interest of time, I'm gonna skip ahead. Just showing you the post-op film, here's the stalk preserved, uh, the, uh, closure, the optic uh chiasm here, and the nasal septal flap. The great news about the endonasal approach is there's no retraction of the brain, so there's no flare signal in the brain after removing these tumors. Uh, this is a patient who had two craniotomies for a cranioppharyngioma. You can see the damage that's been done to the brain from those prior surgeries. He had a tumor that was just in the optic nerve area. I'm gonna skip the video and just show you the post-op film, we're able to remove the tumor and the nerve is well decompressed. Uh, this is just one of the larger ones that we've done recently, endonasally. Uh, even a tumor like this, uh, can be taken out endonasally, uh, and you can see, uh, the post-op film showing a radiographic gross total resection of the tumor. Um, when we compare endonasal to transcranial surgeries, uh, we find that the extent of resection for endonasal surgery, which is this gray bar, is actually greater for cranial pharyngioma than it is for transcranial surgeries. Um, the rate of CSF leak is higher, although we quickly review our rates. But the more important thing for cranioppharyngioma is visual outcome is better. This is visual outcome after endonasal surgery compared to transcranial surgery, and that's because we're coming in from below, and we're not manipulating those optic nerves. We've done about 85 patients overall, gross total resection rate about 86%. Um, and greater than 95% resection in 95% of the patients. Visual improvement in 78% and our CSF leak rate, I want to highlight is just about 2.4%. And certainly for craniopharyngioma we do get a lot of DI and pan hypopituitary when we are going for gross total resection. We've done 11 pediatric patients, average age about 8 years. Sizes range from 1 to 42 cubic centimeters. 6 are cellar supracellar, 5 purely supracellar, 4 re-operations, gross total resection rate in about 45%. Um, but you have to understand intentional subtotal is often the goal in the pediatric population. Fairly frequent anterior and posterior dysfunction. 2 patients only had a greater than 9% increase in their BMI. Visual functions stable or improved in over 70%, and all children except for one were back to an academic environment, 10 in a grade appropriate for age. 1 CSF leak, one with visual loss, and one abscess. I'm gonna skip this re-operation data, uh, and just summarize that the endonasal endoscopic approach is certainly viable in the pediatric population. After age 4, there are few, if any, limitations. Con sphenoid easily converted to a pneumatized sphenoid with a diamond drill, and the key for us has been the collaboration between an endoscopic adult surgeon, uh, and a pediatric neurosurgeon. We do all the cases together and have had a very fertile collaboration. Thank you very much. Ted, that's, uh, and we live that, that's wonderful, and, uh, I'll, I'll first start off by saying that the perceived limitation that we all believed 15 years ago and that this couldn't be applied in children because of limited size of the nares non-pneumatized sinus, it sounds like other than an age less than 4, are there any other anatomical concerns in the pediatric population given those perceived notions? Um, you know, the width of the nostrils is another one that we worry about. Um, it is possible, you know, we use a, a sheath to irrigate, and obviously you can take that sheath off and suddenly your scope goes from 4 millimeters to 2.7 millimeters. So that's something we've done from time to time to look around. Um, but the instruments, we use the same instruments as an adult. Uh, same scope holder, same scopes, uh, we really haven't had a lot of uh changes that we've had to do remarkable to hear. Thank you. Uh, a couple of, I wanna remind everybody this is interactive so all along the talks we're getting questions, very good questions that are coming in. I want you to address some of those since we have uh a couple more minutes before our next speaker. Very good question that came in, uh, has to do with the encephaloces. If these are due or presumed due to intracranial hypertension, do you shunt the patient first? How do you deal with the increased intracranial pressure issue? Yeah, so what we like to do is first try to um repair the encephalocele. Uh, and see if it holds. Uh, we've only shunted patients who have recurrent encephalo heals. If they clearly have hydrocephalus, we'll treat the hydrocephalus with a shunt. But if they don't clearly have hydrocephalus, we'll try to just repair it. We put them on acetazolamide for about 2 weeks after our surgery to make sure everything heals up. If it recurs, we'll shunt. And you said you've done that once out of how many patients roughly do you have an idea that you've shunted somebody postoperatively for an, oh, probably 3 or 4 times out of 40 cases. Another great question that came up during one of your wonderful videos. There was the fluoresce that you could see in the in the subarachnoid space. Can you give us a A very quick response as far as how you use that and when you use that. So we give a low dose, uh, it's a 0.3 of 10% fluoresce. We dilute it in 10 cc's of CSF. We pre-treat with Decadron and Benadryl because the literature has shown some adverse effects to high doses of intrathecal fluorescine. We studied it and we really haven't had any allergic arachnoiditis or problems with the fluoresce. Um, but the key is to give a low dose and pre-treat with steroids, I think. OK, thank you. Um, Jeff may address this last question. I'll go on before our next speaker. Uh, does anybody know the long term implications of, uh, uh, arrested skull-based growth in a child with lack of pneumatization 10 years down the road? Yeah, that's a great question. Honestly, I, I don't know. Um, the patients we followed don't seem to have had any long-term problems with that, um, but I can't say we've studied it in any detail. Sure, that's amazing. Thank you.