Intraventricular Tumors: Considerations for Endoscopic Surgery

Podcast Transcript

Introduction: Neuro Pathways, a Cleveland Clinic podcast exploring the latest research discoveries and clinical advances in the fields of neurology, neurosurgery, neuro rehab, and psychiatry.

Glen Stevens, DO, PhD: Intraventricular tumors are rare types of brain tumors that can block the flow of cerebrospinal fluid and result in obstructive hydrocephalus. Surgical resection is the main treatment approach with minimally invasive endoscopic surgery offering several benefits compared to conventional methods, including reduced risk of complications, faster recovery time, and minimal scarring. In this episode of Neuro Pathways, we're discussing the surgical management of intraventricular tumors and considerations for the endoscopic approach. I'm your host, Glen Stevens, neurologist/neuro-oncologist in Cleveland Clinic's Neurological Institute. And joining me for today's conversation is Dr. Sarel Vorster. Dr. Vorster is a neurosurgeon in the Rose Ella Burkhardt Brain Tumor and Neuro-Oncology Center within Cleveland Clinic's Neurological Institute. Sarel, welcome to Neuro Pathways.

Sarel Vorster, MD, MBA: Thanks much.

Glen Stevens, DO, PhD: Sarel, we've known each other probably for 25 years at least.

Sarel Vorster, MD, MBA: Yes.

Glen Stevens, DO, PhD: So, I don't want you telling any bad stories about me. But others out there may not know you. Tell us a little bit about yourself; where you're from, how you made it to the clinic? A little bit about your journey.

Sarel Vorster, MD, MBA: Well, I'm native South African and I frequently still go there, I love the place. And I also love Cleveland. I came here in the '90s, did my residency and training here, and then went back to South Africa for 10 years and I've been back here again for, I guess, 13 years.

Glen Stevens, DO, PhD: To start off, provide a brief overview of intraventricular tumors or lesions and how they are diagnosed?

Sarel Vorster, MD, MBA: Well, I guess the difference between an intraventricular tumor and all the other tumors we see is that the CSF space has become involved. And so they may present with an entire different clinical picture. With conventional tumors or tumors we see out in the cortex of the cerebrum or the white matter, they usually present with whatever function is lost based on which area they present in. Whereas with ventricular tumors, they might present with symptoms of hydrocephalus, which are quite different.

Glen Stevens, DO, PhD: Tell our audience exactly what hydrocephalus is and the type of hydrocephalus that tumors usually cause.

Sarel Vorster, MD, MBA: Well, we can step back for a minute and say the brain has a wonderful washing out system called cerebrospinal fluid, which is mostly produced in the brain in the ventricles, which are the cavities inside the brain. We produce about 500 CCs of this fluid per 24 hours, but we only have about 125 CCs in the system, which means this car is having an oil change four times a day. This fluid is washing out the brain and is important to carry hormones around, get rid of metabolites and so forth.

So, when tumors enter into the ventricular system, that can cause problems with the CSF flow and the system that it represents.

Glen Stevens, DO, PhD: And different types of hydrocephalus, you have obstructive you have...

Sarel Vorster, MD, MBA: Yes. Usually you can get both with tumors, so if tumors are known for shedding debris or proteinaceous material, that can cause problems with the reabsorption of spinal fluid. The spinal fluid gets produced in one area and reabsorbed in a different area. If one has a lot of debris or proteinaceous material in the fluid, you can develop what doctors call communicating hydrocephalus, which means you're basically producing a little more than you're reabsorbing, which is more of a slower, even sneaky type of presentation for the patient that might present with subtle headaches or subtle cognitive changes which slowly get worse over time.

Another form might be the obstructive form where... Once again, we have to take a step back. There's a series of caverns in the brain and the fluid flows through these caverns, but they also flow through the brain tissue. The fluid that goes through the caverns, we like to call that the bulk flow. This bulk flow, if it's obstructed by the sheer mass of the lesion, can cause backup and distension of the ventricles. Now, if you get that kind of hydrocephalus, your presentation is much more acute. So, patients may present with altered mental status, confusion, severe headaches, or even unconsciousness.

Glen Stevens, DO, PhD: When you discuss the shedding of cells and affecting the resorption of the CSF, this would be in someone that has leptomeningeal disease, those types of things?

Sarel Vorster, MD, MBA: Yes. That's a good example. Yes.

Glen Stevens, DO, PhD: And those patients probably need to be shunted in those cases.

Sarel Vorster, MD, MBA: Yes.

Glen Stevens, DO, PhD: In the cases where we're talking about these intraventricular tumors, a lot of them are fairly benign tumors. We can see subependymomas, central neurocytomas, meningiomas, choroid plexus papillomas. We can see colloid cysts, which everybody gets scared of in medical school when they talk about the colloid cyst. You can tell us your experience with that in a little bit. The subependymal giant cell astrocytomas that tend to obstruct. I always tell patients it's a little bit like too much hair in the-

Sarel Vorster, MD, MBA: In the drain, yes.

Glen Stevens, DO, PhD: The drain can't drain anymore and you have to remove it somehow. One of those options, which is why you're here today, is to tell us about endoscopic surgery. Tell us what endoscopic surgery is in terms of what you do, because there's lots of different types of endoscopes.

Sarel Vorster, MD, MBA: Yes. Well, I'll step back a minute there. I guess one thing to realize is if a tumor enters into your ventricle, it's a whole different approach because you're dealing with the mass effect of the lesion, as we do with tumors anywhere in the body, it's ability to push on other structures and cause dysfunction that way, but we're also dealing with the biology of the tumor, obviously. And so the degree of resection and what's feasible, and as you know better than I do, the interaction between the surgical and the oncologic approach to the lesion as a second portion. And then thirdly and uniquely is the idea that it also is present in and around the spaces where the spinal fluid is, which implies that the tumor cells could be spread around. And it also implies that fluid can be blocked as we discussed. So over the years, surgeons have always been kind of nervous about operating on things that go into the ventricles because of one of the earlier things, namely the idea that you could spread things around or cause bleeding as the cells enter into the fluid.

And that's still a concern even in modern surgery when things are near the ventricles. We were a little bit concerned that we might be able to spread something around that may have been focal before. So when it comes to malignant tumors, for example, we probably would not try to do that endoscopically. It might be better to do an open approach. Whereas if things are more on the benign end of the spectrum, it becomes more feasible to do these endoscopic approaches. And they're very appealing of course, because, as you mentioned, the minimally invasive nature of it, a very small incision and so forth, is appealing to modern patients that expect us to deliver the same quality that they've become used to or expecting from the Cleveland Clinic. But they also would like to have the minimally invasive benefits.

Glen Stevens, DO, PhD: So surgeries that you do endoscopically, where do you go in? Do you go in frontal lobes, parietal lobes, or depends on exactly where the tumor is that you're going after? Can you go from multiple different trajectories?

Sarel Vorster, MD, MBA: Yes. These things don't develop in silos. So endoscopy has been around for longer than 100 years, actually before shunt. Most people know what a shunt is, which is maybe around 1950 or after the second World War, whereas intercranial endoscopy actually comes from around 1910 or something. I think few people know that. So the endoscopy, although it's "a modern technique" actually predates shunts, which people think of as kind of an old-fashioned technique sometimes. But anyway, regarding your question about the entry, one of the technologies that has developed, and a lot of it here at the Cleveland Clinic, has to do with stereotactic image guidance, which is this ability to plan on the preoperative MRIs where the trajectory would be through the brain. A brain doesn't have many landmarks that you can follow, like you would, for example, if you're opening the abdomen, you can see the organs and you can kind of tell where you are. The brain is not like that.

So the development of these image guidance systems have allowed us to develop many trajectories towards the ventricles, like as you said, depends on where the lesions are and what we're planning to do and what we're aiming to accomplish with these trajectories.

Glen Stevens, DO, PhD: And is the endoscope, is it firm? Is it flexible? There are different types of endoscopes. What do you use here?

Sarel Vorster, MD, MBA: Well, yeah, we have different types. All of these things have evolved over time. And in the '90s when I started doing it, we thought we were so advanced. And when I started looking up the history, I noticed that a urologist was doing it in 1910. So that was a humbling moment for a brain surgeon. But anyway, the types of scopes have also evolved. Since it's the brain, we don't have the luxury like we do say on the abdomen where they can insert four, five, six different ports through the abdominal wall because that's really your only limitation is the abdominal wall. So they're doing wonderful things as we know. Even surgeries that previously were thought to be quite invasive, they can do now because of their ability to have multiple ports. And that also introduces the concept of having bimanual using both your hands, which is important to surgeons.

So when it comes to transcranial endoscopy, which means coming at the ventricles mostly from the upper part of the brain, we don't have the luxury of putting in two or three port through somebody's brain because each trajectory goes through function of some sort. So we had to develop new tools and new techniques at first just to use one trajectory and to use a very small trajectory because patients are very clever. They ask clever questions, "Doctor, how are you going to get this camera into my ventricle?" "Well, we have to put something through the brain tissue." Fortunately, the brain fibers are mostly oriented from the inside to the out. And we've learned from very extensive experience with ventricular catheters and so on that this can be done safely. And the preferable area is usually in the frontal lobes where function is less densely represented. So we usually put in a sheath first.

So the sheath looks like a giant IV. It's still quite small, but it looks like an IV. So you insert this with the use of the stereotactic image guidance into the correct position, and then you peel away the sheath to shorten it and fire some that to the surrounding drapes. So you basically end up with a small tunnel from the outside to the inside after removing the obturator. That enables you then to insert the endoscopic equipment into that tube. And that's only the start of the problem, because whatever you're inserting, you might be able to look around, but you can't do anything. So that required innovation. And so the modern cameras have several working ports. So there might be one that holds the actual endoscope, the lens, so you can see, and the ones we use now have, for example, three working ports. So you could theoretically put three smaller instruments into the scope. But as they come out the front, they're right next to each other. They're very close together.

So we usually use one at a time, but you can already see the limitations that's inherent there. And one other important thing is maybe people don't realize this, but with most forms of endoscopy, there's like in a knee or a shoulder or something, there would be ongoing irrigation because there might be bleeding. Now, if you irrigate into a brain, there's obviously a pressure problem. So whatever goes in has to be able to come out. So you can't pack too much instrumentation into this sheath. You have to make sure that there's adequate opportunity for the irrigation to come out. And the irrigation is critical because if you don't have the irrigation, you can't see properly.

Glen Stevens, DO, PhD: So what's the diameter that we're talking of these?

Sarel Vorster, MD, MBA: The outer diameter is about five millimeters, so it's quite small. And the camera's slightly smaller than that.

Glen Stevens, DO, PhD: So you go in there and you biopsy something or you grind something, you're trying to remove a tumor.

Sarel Vorster, MD, MBA: Yes.

Glen Stevens, DO, PhD: How do you pull it out?

Sarel Vorster, MD, MBA: Well, we started out with the simplest thing you could do, and which was most required really, was to do biopsies. So that we could get to lesions with. Otherwise, we could get anywhere in the brain with open techniques. But the surgeries become much larger and the potential for damage becomes more. So it started out with biopsies. And then over time, as instrumentation improved, we started having, for example, different types of forceps. So we might have a small scissors or a small grasper, something that you can fenestra something with and so forth. So there's a range of instruments nowadays.

And then the other innovation has been, you asked me earlier about the scope, the instruments become flexible and the endoscopes become flexible. So you can insert the camera and then you can, similar to having a colonoscopy or something, the operator has the ability to turn the tip of the camera around. And so that enables us to go to different areas with that flexible scope.

Glen Stevens, DO, PhD: So where's the technology going to go for this? Because obviously limited by the number, as you say, ports that you can put in.

Sarel Vorster, MD, MBA: Yes.

Glen Stevens, DO, PhD: And I'm not sure how that's going to change.

Sarel Vorster, MD, MBA: Yes, that is kind of a hard line really. Unfortunately, it's difficult to innovate around that. One possibility that people have looked at is to actually put in more than one port.

Glen Stevens, DO, PhD: Then you could use both hands.

Sarel Vorster, MD, MBA: Yes. So you can use both hands and get a different view of things. Because oftentimes tumors have their blood supply, which is what a surgeon is interested in disrupting. So often you need more than one trajectory to get to, you might say, the dome of the tumor and maybe another trajectory to get to the blood supply. It's not often possible to get both through a similar or through the same view. So where we now go mostly frontal, which, as I said, has less dense, first of all, of the brain's important of course, but function is less densely packed. And another area that's being looked at is the inferior parietal lobe, which also allows some degree of freedom in terms of placing these sheaths into the ventricle, which will help us a lot because a lot of the things that we are trying to treat are in the back end of the third ventricle, which is difficult to access from the front.

Glen Stevens, DO, PhD: So another procedure that's commonly done to try and avoid putting a hardware in for a shunt is doing a third ventricular ostomy. Tell us what that is, and.

Sarel Vorster, MD, MBA: Well, that's part of the idea of the three prongs that we're trying to do. The biology, the mass, and the CSF flow. So the endoscopic third ventricularostomy has become known as an ETV is a way of making a small hole on the inside of the floor of the third ventricle. So we have two lateral ventricles that drain passively into the third ventricle, which is more or less right in the middle of our head. And there's a structure called the aqueduct, which is a natural narrowing between the third and the fourth ventricle. So many people have lesions or tumors that obstruct this flow through the aqueduct. And so the innovation there was to make an opening somewhere else. You mentioned the hair and the drain earlier. Well, I guess you could run a hose out the window out of your bathtub, that would be a shunt, or you could make a second hole in the bottom of the bathtub, which is what we're doing with the third ventricularostomy, which allows the fluid to escape to the same space where it would've gone if it had exited through the fourth ventricle.

Glen Stevens, DO, PhD: So it's going into the basal cisterns then?

Sarel Vorster, MD, MBA: Yes, that's correct.

Glen Stevens, DO, PhD: And then we'll recirculate.

Sarel Vorster, MD, MBA: Yes, exactly. Yes. So that's very nifty because doctors know that shunts have a high complication rate, although there are wonderful innovation. So it's very satisfying to be able to offer some patients, not all, the ETV procedure instead of having an implant like a shunt.

Glen Stevens, DO, PhD: And the risk of the third ventricularostomy closing up again?

Sarel Vorster, MD, MBA: It's quite small. In the pediatric population, it's a little higher because their brains are still maturing and tissues are forming. But in the adult group, I wouldn't say it's a rare, but it's kind of unusual to have a closing off. We also have techniques to make these little holes a bit more durable, where we have small soft castors that have a balloon at the end so that you can expand the area. Unfortunately, the area of the anatomy that was identified to do this procedure allows that without causing damage.

Glen Stevens, DO, PhD: I guess sort of going back a little bit, the advantage of having obstructive hydrocephalus is you have a bigger CSF space, so you have a little more room to work.

Sarel Vorster, MD, MBA: Well, you're right.

Glen Stevens, DO, PhD: Yes, no or not?

Sarel Vorster, MD, MBA: No, you're right. I mean, interestingly enough, one of the oldest theories in medicine is by the famous Roman physician, Galen, who said that they weren't really sure what spinal fluid was. They thought it had something to do with temperature control. And the way they did their dissections at those times were, I mean, postmortem, but to remove the brain. And there was fluid, and they didn't really see the cavities. So it's only fairly recently that people knew there were cavities. And when we started looking into endoscopy in general in the body, people obviously needed a cavity to put a camera into. And so some people have small cavities or small ventricles. Some pathologies, for example, cause you to have small ventricles, and then endoscopy cannot be done.

Glen Stevens, DO, PhD: So I'll just climb back just a second about the camera that you mentioned. 2D or 3D?

Sarel Vorster, MD, MBA: No, it's 2D because, once again, we have the single trajectory. So some of the things we use like the modern cameras outside of the body to try and move away from microscopes, which are big and chunky, have some 2D capability and requires the surgeons to use special goggles to be able to appreciate that. But we don't have that in the cranial...

Glen Stevens, DO, PhD: But you would have to, right? If it was a 3D, you would have to wear some type of goggle, which then-

Sarel Vorster, MD, MBA: Yes, yes.

Glen Stevens, DO, PhD: Would add another...

Sarel Vorster, MD, MBA: It's another thing.

Glen Stevens, DO, PhD: ... difficulty.

Sarel Vorster, MD, MBA: Yes.

Glen Stevens, DO, PhD: So the fornix, involved a lot with memory, does it come into play a lot with the tumors that you'll treat with this, and what happens if you get into the fornix?

Sarel Vorster, MD, MBA: Well, we're getting deeper into depending who our audiences, our physicians will know. But if we go into the ventricle, there's all kinds of important things in there. It's right in the middle of the brain, the fornix being one of them. The fornix is part of an extensive circuit, which is part of the main memory systems of the body. And the fornix surrounds one of the holes where we place the camera to go from the lateral ventricles to the third ventricle. Now, fortunately, if there's obstruction, this hole has been naturally slightly enlarged. But that's something we try and get an idea on the preoperative MRIs, and usually we can see if the foramen of Monro is going to be adequate to be able to pass the camera without injuring the fornix, which is what we fear to do. It also depends on the trajectory. So we spend quite a bit of time planning the perfect trajectory, so we wouldn't have to manipulate the fornix when we go through the foramen of Monro.

Glen Stevens, DO, PhD: So it sounds like the presurgical planning is maybe in some ways the most important thing you're doing.

Sarel Vorster, MD, MBA: When I'm teaching younger surgeons about this, I tell them, "Well, this procedure, everything is really about the preparation." Because in conventional surgery, we have ways of making adjustments as we go along. We can control bleeding, we can extend the approach a little bit. We've got multiple ways that we can change a little bit as necessary. But with this specific procedure, those margins are much narrower. So we go to great lengths to make sure everything works perfectly, the irrigation systems, the cameras, because as you can imagine, if any of these things fail, it's not like there's so many plan Bs except moving to an open surgery.

Glen Stevens, DO, PhD: So let's go onto that endoscope versus an open surgery. Tell us examples of why you'd use one versus the other. Are you still doing intraventricular open surgeries or?

Sarel Vorster, MD, MBA: Yes, there are.

Glen Stevens, DO, PhD: And how do you approach it?

Sarel Vorster, MD, MBA: As always, these things, we don't move completely from one to the other. We tend to expand our toolbox, so to speak. So we see endoscopic surgery, not as something that's going to take over brain surgery, but something that's another option for us. And we find applications that are most suitable. So, some pathologies, like colloid cyst, for example, are uniquely suitable for endoscopic removal, whereas other things may not be. So we use both.

Glen Stevens, DO, PhD: And what's the approach? Do you have to go in or hemispheric to get into the brain, or not necessarily?

Sarel Vorster, MD, MBA: Yes. If one wanted to approach to the same part of the brain, you have a few options. You can do transcortical approaches, which are basically larger versions of the smaller sheath. I wouldn't like to mention specific brand names, but there is kind of an expandable type of sheath that we use nowadays, which you put in and it's stretches a little bit. So you have a slightly larger tunnel that you can go through when you use bimanual techniques. And then of course, open surgery to that area would require interhemispheric type of approach.

Glen Stevens, DO, PhD: And I'm sure, as you mentioned, if you're looking at your pre-planning and your trajectory, you just can't get there safely.

Sarel Vorster, MD, MBA: Yes.

Glen Stevens, DO, PhD: Then it just answers the question for you, right?

Sarel Vorster, MD, MBA: Well, it's fascinating. If you step back and you just think of brain surgery in general, you've got a tightly fitting organ inside a skull. So we really make a study of all the little crevices and spaces that we can use to create a little bit of space that's required to go wherever we need to go. So we are very aware of this limitation. And of course, also if the brain is swollen, if there's pathology, that adds another challenge. So the idea of having small spaces to work through is really something that really defines neurosurgery. And so that makes trajectories and approaches very important for us, perhaps more so than with other types of surgery.

Glen Stevens, DO, PhD: Do you do specific imaging? Are there images that you would do?

Sarel Vorster, MD, MBA: Yes, we use, it depends which type of MRI machine. Sometimes it's called CISS Sequences, some other machines it's called the fiesta sequence. But it's basically a thin cut type of version, which gives you more information about fluid spaces and you're able to see thin membranes and fluid areas, cisterns, which you might want to examine.

Glen Stevens, DO, PhD: And the endoscopic training, someone wants to get interested in this, that wasn't offered in their fellowship. How do I get trained in it?

Sarel Vorster, MD, MBA: I think people do fellowships in things like skull-based surgery or on neuro-oncology, and this is part of it, one part of it. Another way one might want to, well, you could have an exposure to it in your residency, but it's not available everywhere. So as a patient, one would've to make sure that not only the expertise of the surgeons, but perhaps as importantly, the equipment is there to be able to do it.

Glen Stevens, DO, PhD: And how long do you think it takes somebody, maybe it's a loaded question, but do you feel that someone needs to do a certain number of cases or not necessarily?

Sarel Vorster, MD, MBA: That's a good question. I know there's a book where people examine when you become an expert, and I believe the number is 10,000 hours.

Glen Stevens, DO, PhD: 10,000 hours is that book.

Sarel Vorster, MD, MBA: Yes. So there's not many people that do 10,000 hours of anything. And when it comes to brain surgery, just because of the nature of the pathology, if a neurosurgeon has done 100 of something, that's considered a huge amount. Whereas in some other surgeries, maybe 1,000 is considered a big amount. In neurosurgery, there's hardly anybody that's done anything more than a few hundred or maybe a thousand or so. So that means there's less opportunity to learn by experience. So I call that eminence-based medicine. Now we practice evidence-based medicine, but eminence-based medicine to me means we stand on the shoulders of giants of our predecessors. So you don't have the option of doing hundreds of surgeries and getting better and better at it. You have to get good at it very quickly.

Glen Stevens, DO, PhD: Right away.

Sarel Vorster, MD, MBA: Yes, hopefully right in the beginning. So there are simulators and things that we use for this. And obviously when we do courses on these things, we use cadavers and so forth to get over that first hump. But it requires discipline and humility and introspection for surgeons who want to embark on this to make sure that they feel they have the right training and learn from the right places how to do it properly.

Glen Stevens, DO, PhD: And the length of the cases are these cases that, again, everything is so variable, it's hard to be average on these types of things, but if you were removing a colloid cyst, is this a half an hour surgery, is this 10 hour surgery?

Sarel Vorster, MD, MBA: If we're just doing a simple diversion, it can be done in less than an hour. If we start removing things, it takes time. And so four or five hours is more likely, which would probably compare to an open procedure in neurosurgery.

Glen Stevens, DO, PhD: Okay. So final takeaways for our audience.

Sarel Vorster, MD, MBA: Regarding endoscopy?

Glen Stevens, DO, PhD: Yes.

Sarel Vorster, MD, MBA: Yes. I think it's exciting to know, as I said, nobody wants brain surgery. We're all afraid, and we hope that whoever the surgeon is knows what they're doing. And I guess we don't want to hurt and we don't want to have big incisions. It's very personal to have surgery on your brain. So I think it's good for our audience to know that we're always moving forward and always developing new things to try and make our approaches safer and smaller.

Glen Stevens, DO, PhD: Well, listen, it's been a very interesting discussion. I always enjoy chatting with you and listening to your perspective on things and keep up the good work.

Sarel Vorster, MD, MBA: Well, likewise. Thanks for having me.

Conclusion: This concludes this episode of Neuro Pathways. You can find additional podcast episodes on our website, clevelandclinic.org/neuropodcast, or subscribe to the podcast on iTunes, Google Play, Spotify, or wherever you get your podcasts. And don't forget, you can access real-time updates from experts in Cleveland Clinic's Neurological Institute on our Consult QD website. That's consultqd.clevelandclinic.org/neuro, or follow us on Twitter @CleClinicMD, all one word. And thank you for listening.