Minimally Disruptive Subcortical Neurosurgery in Children - Concepts of the...

Um, we're gonna move on to our, our, if you can, uh, if you haven't already, uh, stopped sharing your screen. And we'll ask uh Erin Keena to go ahead and get teed up by uh sharing your screen and uh showing us uh your first slide. Um, That OK, Sandy, yep. Are you there, Aaron? I'm here. Can you hear me? Yeah, so I, I, I'll say that, uh, I'm always intrigued when there's not just the, the title of minimally invasive, but minimally, minimally disruptive. Subcortical neurosurgery in children. Um, I, I think there's, there's an interesting, uh, uh, uh, tenet to, to talk about here, and that is, you know, when we talk about minimally invasive, uh, there, there's a continuum between the standard microsurgical routes to the ventricular system, uh, and then the purely endoscopic systems, and then the, the in between with regard to trying to capitalize on what we've all been trained to do, and that's bimanual micro neurosurgery. With the minimally invasive concept of an endoscope or an endoscopic sheath, and this, I think mirrors or marriages, both of those, those, uh, very basic elements and fundamental principles of safe neurosurgery. So, so with that, enlighten us on the, the minimally disruptive subcortical approaches of the ventricular system. Great to see you, Erin. Thank you. It's really a pleasure to speak today and truly humbling to follow all of these incredible giants in the neurosurgery. Um, I will definitely be replaying these videos over and over in the future. Um, but for the trainees in the audience, children are not just miniature adults. Uh, I think we've covered that across the morning. Um, they have unique tumor locations, and many of them are intraventricular or paraventricular, and we have that corridor to access them by. They also have unique pathologies, with the most inspiring thing about pediatric brain tumors is that over 80% of them are curable, as you can see, both benign and malignant tumors are below. And finally, as opposed to adults, the immature brain is still undergoing myelination. While the cells might be more vulnerable to injury, there's still neuroplasticity, ongoing synaptogenesis, synaptic pruning, um, which allows for a unique recovery from the surgeries that we do do on these children. My surgical goals whenever I approach a case are um complete tumor resection that's required to achieve an 80% cure rate, relieve mass effect from tumor and hydrocephalus, but also, as Sandy pointed out, picking the right surgery for each individual child. Um, we need tissue for not just pathologic diagnosis, but we also need it in the modern era era for genomic and molecular analysis and investigation as the WHO is now including these in their guidelines. And we always want to obtain a neurologic outcome and a quality of life that we would desire for each of our own family members. Our goal is a gross total resection, but how we access this lesion is key. And we should approach each, uh, each brain is, um, that all tissue is relevant, that there's not just eloquent cortex and non-eloquent cortex, and we need to preserve all the fiber tracts en route to the lesion regardless of the corridor. Subcortical injury is a real problem. Um, from the awake craniotomy data, um, we know that when cases develop new intraoperative neurological deficits, 90% of these are occurring during the subcortical dissection. So by preserving subcortical areas during tumor resections, we may reduce the incidence and severity of neurologic deficits. Um, we want to avoid subcritical injury by optimizing fiber tract preservation. So a parafascicular trajectory minimizes sheer forces applied to the white matter tracts by running parallel, um, to the main white matter tracts, as you can see in the diagram to the side. Also by choosing a transocal. Route parafascicular trajectory, it reduces the amount of brain traversed in route, um, to reach lesions and by using a tubular retractor, we can distribute the forces radially, thereby protecting the displaced tissue rather than just simply retracting them with malleable retractors. Brainbath combines all these philosophies into a unique approach. As you can see, it's a clear navigable tumor retractor, um, compatible with multiple image guidance systems. It comes in multiple diameters and lengths. It's ideally used with the exoscope, um, but it, it can also be used with the microscope, um, which I've used many times. It can also be used with the endoscope and or as an endoscopic assist as we heard in the previous talks. Importantly, it allows for bimanual surgery with keyhole instruments, advanced neuronnavigation, including tractography, allows for complete tumor resection and advanced tissue preservation using the tissue preservation device, and it can also be used with ultrasound down the tube and white matter tract mapping intraoperatively. So it's expanded our um surgical options for resecting subcortical lesions and intraventricular tumors. So not just doing a craniotomy or borehole neuroendoscopic approach and endoscopic assist, but this allows us to do a mini craniotomy and resect it with this new. Traditional craniotomies have been employed for over 100 years. It's great. There's a large corridor that gives you great visualization. You can manage hemostasis very well. You have a high tissue yield. You can map out your white matter tracts, but the traditional craniotomy is very invasive. Um, we can cause injury. It's limited by. Location due to risk of morbidity. And also, as you look at this, um, you know, scan right here, this is a case where if we did a corpus callisotomy in a child with large ventricles, we'd have some collapse of the brain, we'd have egress of the fluid into the subdural space, development of a pseudomeningocele and can also lead to, often lead to prolonged recoveries. For endoscopic resection, um, which I also love to do, we've got the pros of it being minimally invasive. We can take it to eloquent areas with a low complication rate. Um, we have a high diagnostic yield, reasonable tissue yield. But, um, it's challenged by no simultaneous hemostasis. We're limited to one hand, we can't retract that well. Um, and the tumor is removed in very small pieces or more slated with a device like the myriad. We're supposed to brain path or that this is a more minimally evasive approach that we can take to eloquent areas with a low complication rate and a high success rate for diagnosis, allowing us the visualization of white matter tract mapping allows for hemostasis management and the high tissue yield, and the ponds. Being that it does require a small craniotomy and they do about 2.5 to 3 centimeters in diameter and it is a slightly restrictive field. Um, we do have to use extra long keyhole instruments, um, and we can't move that port around a lot once we're in there or we will be disrupting fiber tracks. Well, I still use the endoscope for resecting small lesions not thought to be highly vascular adherent to surrounding tissue, um, such as this is to ependymoma mets and use it, um, for lesions such as this one right here, um, which is a combination of, um, of open and endoscopic. Um, I'm now looking at cases as to which ones would be the ideal brain path case. And in my mind, these are lesions less than 4 centimeters. They can be both subcortical, deep, or mets, lesions that you can access down the long axis of it, um, and accessible through a parafascicular. And to show you a couple of cases, um, this is a 6-year-old girl who presented an acute on subacute presentation and had a large hemorrhagic mass approximately 3.5 to 4 centimeters centered around the caudate. Um, it was angio negative. Um, when she deteriorated and had a quality of life that we would not desire, we did an MRI, um, we did MRI with tractography, um, in order to, um, isolate where her tracks were and to plan an ideal surgical corridor. Um, in this one, this case, it was frontal, um, to avoid the superior longitudinals. Um, to take this case to the operating room, you, um, do need Mayfield pins, um, and, uh, so she's in a head frame to allow for neuronnavigation. Um, I perform a minimal head shave and a cosmetic incision behind the hairline and, um, send her a 3 centimeter craniotomy, as you can see, um, right here. Um, it was a very uncomplicated resection. Headaches resolved by post-op day one, appetite improved, normal level of alertness, and she was discharged post-op day 2, and had a great recovery back to normal activities within. Um, an example of another case this is through a posterior corridor. Um, this is a patient with a deep, um, progressive lesion, um, near in the occipital cortex, um, where a non-diagnostic biopsy, um, was performed. This is about a 2.5 centimeter, round lesion, and following this biopsy, she actually had a visual field cut. Um, she came to our institution with this lesion still growing, and, and she had seizures, so we performed a trans-sulcal approach via the parietal occipital sulcus where the tumor was just a few millimeters from the base of the sulcus. Thus we were able to avoid the white, um, the white matter tract optic radiation. Um, was a gross total resection of a low grade glial neuronal tumor, um, and she was neuro intact aside from her pre-existing fill cut, and she was discharged at 48 hours later. So I think if this approach had been used upfront, um, she could have avoided having a visual field. Um, when we get, uh, approaching deeper lesions like a cranioppharyngioma, if your goal is to do a, you know, subtotal resection, debulking, and then send for radiation, um, the brain path is ideal for many of these cases. So instead of performing an inner hemispheric approach, uh, um, we use the brain path, um, uh, in the area of Coco's Point transfocal approach, and we're able to debulk the entire third ventricular component up to the level of the solid partially calcified. thalamus, um, and send her on, um, to radiation, you know, once again discharged within 48 hours. As we approach these, um, larger lesions, I also think it's a very, um, helpful adjunct. Um, this is an infant with increasing microcephaly, nausea, and vomiting. Um, MRI showed severe hydrocephalus, uh, with the roid plexus lesion in the roof of the third ventricle extending into the left frontal horn. Um. Additionally, I would have performed an inner hemispheric craniotomy, but as I mentioned before, oftentimes these places are plagued by the brain collapsing and some fluid egress around the, um, brain surface forming a subdural hygroma, a pseudomeningocele, and it's hard to keep the CSF in the right compartments, um. Even in infancy, we can do this. This is with um stealth, um, axiom EM um navigation, um, a small craniotomy to the side of the fontanelle. Um, and I actually passed the brain path sheath with ultrasound in his case. Um, it was a third ventricular choid plexus papilloma, and by doing this with Brain path, um, yes, his brain did, um, collapse in a little bit. He never developed a pseudomeningo cell. He recovered well. I did not place an EVD, um, and he was home within, uh, 48 hours. Um, this is an example of a deeper intraventricular case of a, um, healthy nine month old who presented, um, after falling off the bed, and the CT found this image, um, followed by MRI, of course. Um, we decided to remove this as there was a strong cancer history in the family, and we were worried about, um, that this could be a carcinoma. Um, we planned, um, a trajectory, um, transfocal trajectory, um, past the brain path down. It's just the 50 millimeter um length and the um 14 millimeter diameter sheath. Um. And you'll see that we're using uh stealth navigation in this case. It took us straight down um to the choroid plexus lesion which really started to, um, extend out to the sheath. Um, this is just, you know, we can use two instruments, um, down the channel which is very helpful. So there's a suction and a bipolar. Um, at this time, this is kind of rolling it, um, around to get to the, um, the vascular base of it. I kind of speed it up a little bit. And the benefit to this is that you can remove um this entire lesion on block so you actually don't have to morssulate it or cut it up into small pieces and especially for choroid plexus tumors this preserves the um architecture um for the pathologists um so so that they can make that important critical diagnosis. Um, they then started applying it to, um, more of our cavernoma population and specifically I'll show you two cases of Rolandiccavernoma. Um, the first case that I used it on was a child with a history of medulloblastoma who had craniospinal radiation. And while we thought this was a cavernoma, we could not, um. Exclude the fact that this could have um a a meta metastatic disease component. It could be a recurrent disease. So he presented um with seizures two years after his diagnosis of medulloblastoma um with this 3 centimeter um left frontal subcortical mass. Um, in order to remove that, I did a 3 centimeter craniotomy just off mid midline cruciate dural opening. I used a 4-contact electrode strip to convert phase reversal across what was the central sulcus, which this is the base of, and I did a transocal approach to the central sulcus of the cavernoma. Intra-op neuro monitoring was intact. Um, it was a complete removal, and he was discharged at 48 hours. Neuro intact. There's his pre in his post-op imaging. And similarly, within the month, I had a 15 year old male whose texting was interrupted one night by acute onset of facial weakness dysarthria. Numbness, um, he had a nearly 3 centimeter a bleed as well, um, within the precentral gyrus. Um, we let him finish school that fall or that summer, and, um, once again did a similar craniotomy off midline, confirmed phase reversal in the presence of my uh sulcus, um, and went to the base of the sulcus and resected. He was discharged at 23 hours post-op. Um, this is the first time that I had the chance to use, um, the ultrasound, um, with resection, and, um, what you can see is this is, this is an ultrasound probe that fits down, um, the brain path too. You can see the lesion on ultrasound pre-op. This is his pre-op MRI post-op, you can see that there's no longer a lesion there, um, and there's been, um, complete resection on the MRI. In my personal series, my main operative time was about 3 hours and 11 minutes. Um, and the median length of stay was about 48 hours. Um, extent of resection matched my intended resection each time with. All my patients were intact with the exception of a pre-existing visual field with over 200 cases. In the brain path series you can see that it's being used um throughout the brain um although predominantly stentorial indications and for uh a number of different indications from primary tumors um to secondary tumors or metastases as well um. In the present state, brain resection is safe and efficacious with similar improved outcomes and shorter length of stays, and tissue preservation is crucial with the new WHO guidelines requiring molecular genomics for multiple tumors, um, which resection in this manner allows, um, the preservation of this tissue. In the future, I want to continue to use the tissue preservation system to enhance the DNA and RNA recovery, preserve the tissue to recover viable cells for cell line generation, and preserve tissue for future research of the tumor microenvironment. So that we can move from 1918, um, fast forward to 2018. And, because the way I removed tumors 5 years ago will not be how I remove one in the next 5 years. Thank you. Thank you very much, Karen. That was, that was wonderful. Um, I think one of the questions I have is when you do incorporate an endoscope with um with your, with your brain path, what are the, what are sort of the technical limitations of being able to use the bimanual, um bimanual techniques and, and when, what kind of instruments have you been able to use through the endoscope and the brain path together in these cases? It's a great question. So primarily for the resection I'm using either the exoscope or the microscope. Um, now that's, um, the exoscope gives you more options on where your, your, the patient's head is positioned and the angle that you're coming in at. If you're using the microscope, you have to be very careful in how you're going to position the patient, um, such that the port is, um, as superior as possible in the, um. Build so that you are looking down at an ergonomic fashion. Um, the instruments that we use down the port, um. We, uh, Nico is now making the trio which is uh allows for bipolar at the tip of it. Um, you can use the silver glides. Um, bipolars also fit down it really well. Um, I use the Nico Myriad, um, once again because it preserves the tissue architecture by morselating the tissue, um, and I also like the myriad because it provides the, um. The smallest obstruction in my view because it has a very streamlined handpiece, um, and then of course all of our extra long sections fit down it. Um, I haven't tried to suture nor have I needed to down the tube. Um, that would be a little bit challenging, um, but all of the, all of the instruments that we would use, for example, for a transpinoidal also fit down there and then of course all our micro neurosurgical instruments fit down our rotons and stuff. And that's, it's an amazing collection. Over 200 cases is, is dramatic. Uh, you must be 80 years old by now, collected that many cases. Uh, I know you're not, so you've been very, very, uh, vibrant in the field. The question I have, which is somewhat unclear and it kind of goes against the grain of what I train with. Pure endoscopic, um, approaches to the ventricular system, and that's I have to go over the, the surface of a gyrus and never go through a sulcus. Can you detail a little bit more precisely when you're passing that 15 millimeter, 18 millimeter brain path down the sulcus, how you protect yourself against getting a, uh, a deep arterial. OK, it's, it's a great question. I still think I hold my breath every time I pass the, um, the crocar. So we do, we do open the arachnoid of the sulcus. Um, so I open the arachnoid. I actually shoot for up to about, um, 2 centimeters when I can. I think you really only need about 15, but I think a little bit wider can't hurt, um, and that's just done standardly with a, you know, 11 blade or a, um, arachnoid knife. And you go down to the depth of the sulcus, so I opened the, I open the arachnoid at those, at the superficial access, uh, um, and then what we do next is I always actually valsalva, um, the patient, um, and so. I open the 15 blade. Um, I actually take just the bipolar tips and I widen the opening just for a millimeter or two and then I pass that trocar using my navigation with a little bit of a valsalva. Um, so it's really important not to give these patients any manitol, not to relieve the CSF pressure first, um, and, um, I. Fortunately, I have not ruptured a vein, haven't ruptured an artery, and haven't had any bleeding. Um, I, I think it's really hard to believe and like I said, I still hold my breath every time, um, but I haven't hit any major vessels, and I think it is because it's a blunt tip and it radially, it, it allows the vessel. to roll off of it, um, and, um, distracts that tissue radially. Yeah, fascinating. And was there a question that came in? I saw that there was a question about using, um, the exoscope and do you use the 3D or 2D version and what have you found to be the benefits of one versus the other. OK, um, I'm, I am personally predominantly using the microscope, um, in my practice, um, and, um, but I would love to have the 3D exoscope. Um, if I had it, I would be using it, um, because I, I do think the visualization is much improved, um, but personally, um, I've been using the microscope predominantly. Wonderful. Great. Thanks, Aaron. That's fantastic.