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Pseudocapsular Resection of Pituitary Tumors

Marvin Bergsneider

November 30, 2020

Transcript

- Hello, ladies and gentlemen, and thank you for joining us again for another session of Virtual Operating Room from the Neurosurgical Atlas. This afternoon, our guest is Dr. Marvin Bergsneider from UCLA neurosurgery. Marvin is a true leader in skull-based surgery. I have personally watched him in action, and I have tremendous respect for his technical expertise. He's also the Chief of Skull Base Surgery at UCLA, as well as the Program Director there. He will be talking to us about resection of pituitary tumors, and he will share with us his technical pearls, which I very much looking forward to learning from. Marvin? Thank you for being with us, and please go ahead.

- Thanks so much, Aaron. And it's a real privilege to participate in this. Congratulations on really having such a successful library that I know our residents utilize this frequently, as do our, my colleagues. And so again, thank you so much. So, today I'd like to talk about pseudocapsular resection of pituitary macroadenomas, because the, I think macroadenomas are a little more straightforward. And this gives us a look at a procedure or technique that as I go through this, I'll explain that I was actually very, I didn't believe it could be done when I was first proceeding to become in this position. So, I have no disclosures. So, what I'd like to cover today is a little bit who, what, why, and how. And the who is about me. I work at UCLA with a fantastic team of skull base surgeons. Most of my experience in the operating room is with a colleague, Marilene Wang, who's a extraordinary head-neck surgeon, rhinologist, skull base surgeon, but we have other members of our team. Won Kim, Jeff Suh, Jivianne Lee, who, together, it's an amazing place to work. And obviously, for a pituitary program, you need a whole array of other people who are listed there on the right too. I'm very grateful to, and it's a great place to work because of the people around me. So, a little about my personal experience. Prior 2008, I was basically working at both UCLA and our county hospital. I'd done a lot of endoscopic and ventricular surgery. Then, I have the opportunity to begin an endoscopic pituitary practice in 2008. And you can see there, since that time, I've done over 1,200 endoscopic and nasal cases, of which about almost 840 have been pituitary adenomas. Everything that you'll see today is endoscopic, but the key technique is not limited to endoscopic surgery, but I think it is easier to do with the endoscope. So, a little bit about what and pseudocapsule resection, full credit I think goes to Ed Oldfield. Ed Oldfield was a master surgeon for pituitary surgery and other surgeries who had amazing practice at the NIH. And it was really, if not the world expert in the resection of pituitary adenomas for Cushing's disease. And this classic paper from 2006, really spells out the pseudocapsular resection as he described it. And I want to note that, you know, Ed did all his procedures using a sublabial microscopic approach. So, as I mentioned, this technique is not restricted to endoscopic approach, but I think it's facilitated by that. What Dr. Oldfield described really was a concept that the normal pituitary, the adenohypophysis has an acinar or a structure. So, it's like a honeycomb where you have acini of secretory cells that are surrounded by reticulin stain in collagen. And as a pituitary tumor grows, it sort of squeezes out the acini and leaves the behind. And this is a pseudocapsule. The pseudocapsule is by his definition, really, it's a pseudocapsule because it's, belongs to the gland. It's not a tumor capsule per se. And classic pituitary surgery, this is how I was taught, is one where the resection maintains the pseudocapsule. Pituitary tumors are soft, and here's an example of just using a curette. And this is how pituitary surgery was done for decades. And it's still done this way because the pseudocapsule in a way, protects the gland and other structures as you move along because you're allowed to scrape with a curette. The tumor, again, the soft tumor off the pseudocapsule. So, why? Why is this important? What I don't feel described was that, microscopically, when he looked at the pseudocapsule, logically, there were tumor cells within the pseudocapsule. So if your resection maintained the pseudocapsule, if in theory, you are leaving behind microscopic cells. And while it would predict then that recurrence rates would be fairly high with the traditional intracapsular approach. And I guess this is cherry picking, that the literature, but if you're looking at publications with very long-term outcomes over 10 years, the recurrence rates are reported to be rather high, and versus, for Ed Oldfield series, and also other series that demonstrated a pseudocapsular resection, that the 10 plus year recurrence rate is less than 10%. And there's probably other reasons why it's not zero, but it would appear, at least by this analysis, that pseudocapsular resection may have an advantage. So, one may ask, well, why not? Why doesn't everybody do pseudocapsular resection if it's obviously better. I would say that it's challenging. And that one of our graduating residents, a couple of years ago actually said that this is one of the hardest things that he had to learn during residency. It was harder than clipping a basilar to aneurysm. He said. And that if you look at my experience, so from February 2008 to June 2010, I basically had one case in which I thought I was able to accomplish this, having to read Ed Oldfield's paper. And it was a firm tuber, about eight millimeters. And they said he was able to shell it out. And I, well honestly, at that point, felt that I didn't understand what Ed Oldfield was talking about because I just couldn't find it. I couldn't accomplish this procedure. Traveling at many different meetings, skull base meetings, and having people present their pseudocapsular resection of a case. I recognize that case. And this is often what they're presenting, is a firm tumor that they're able to shell out. I really had the privilege of having Ed Oldfield come to UCLA as a visiting professor, he gave a wonderful talk. But I think following Atul Gawande's suggestion, I invited Ed Oldfield to the operating room. I had two pituitary cases scheduled that day, and I had him watch me do pituitary surgery. And I think it's something that I will suggest to anyone, that as Atul Gawande says, that even Tiger Woods has a coach. That no matter what stage of your career, it's good to have an operative coach. And he was immensely helpful. He was such a kind gentleman who spent his time, must've been torture for him watching me do this at first. But then he gave me some tips and pointers that made all the difference. And perhaps I was a slow learner, but over the next year, I got up to 8%. And then now, it's at 24%. And what that means, that these are all comers. These are all pituitary surgeries over this time, that about a quarter of 'em, where I'm able to accomplish a full pseudocapsular resection. I'm able to get most of the, they accomplished in about half the patients, another half of the patients. But for me, unless it all comes out in one piece, I don't consider that a full pseudocapsular resection. And there's a reason why many of the patients, it's not even, we don't even attempt it, if they have cavernous sinus invasion, if it's extra diaphragmatic, if it's invaded the colitis, it's not really, you know, the concept doesn't really apply. But it does apply to many and most of the tumors that we operate on. So, I'll show this here. And here's eight cases that for me, looking at these cases, I would at least mentally think I'm going to try a pseudocapsular resection for these cases. And coming into into surgery, I would use the same technique and set up that I'll describe in a minute, but I will tell you that for these eight cases, I was successful in four of them. And these are just examples of cases where either I just wasn't able to find the pseudocapsule or complete the dissection. And only what I consider a partial resection. I think I got a full resection, but the pseudocapsule resection part of it, I could not complete in a fully circumferential manner. So, why is this? And I'm not sure. I know Ed Oldfield as a dear friend, and I know he told me several times that he thought that every tumor had a pseudocapsule, but I'm not sure that, at least in my experience, that's true. And I kind of equate this, or the best analogy is skull lesions, where more benign, slow-growing skull lesions remodel the skull versus the more aggressive ones or invasive ones are lytic. And I think that pituitary tumors do the same thing. And I think, let me show you an example here. So, here's that lytic, I mean, the portion where it got remodeled. And there's perhaps some desmoplastic changes that occur. And versus here, the lytic lesions, it doesn't. And it's kind of what I see is, I can't find it in some areas where the tumor and the gland, I can't identify that. And what I think it is, is that perhaps we're looking at the biology of the tumor, and that the more invasive tumors, perhaps they'll form a pseudocapsule, and this cavernous sinus invasion is even further degree of invasiveness. And in part, this may explain why the outcomes are better with pseudocapsular resections, 'cause perhaps we're dealing with a different biological behavior of tumors, but nevertheless, I think it is well worth learning this technique. So, this is the how, and I will kinda go and break this down into two parts. So, skull base surgery, I think all of you know, you have to set it up. A lot of skull base surgeries, decision-making of knowing which approach to use and you have know your anatomy, and study the films very well. But the approach is our key to enable you then to do the technical part of the procedure. And there's no difference here. Kind of listed what I think are eight keys to success for pseudocapsular resection. And the first part has to do with setting yourself up for success. And you know wide sphenoidotomy. And I'll show examples of all these. You need to be able to do bimanual dissection and keep your field of view with dynamic visualization. And what that means is, no scope holder that to having someone hold a scope allows you to look around corners. And you know wide sellar exposure and a meticulous dural opening. Need to rethink and understand the relationship of pituitary tumors and surrounding structures. And I'll get into that a little bit later. And then, the two things that Ed Oldfield showed me that day in the operating room was, one was the meticulous dural opening. The second was to incise the gland capsule. And this was not obvious to me before, but if you don't open the dura and maintain the gland capsule, it's hard to do this part of the procedure. Then you identify the plane between the pseudocapsule and the normal gland. It's skull base surgery. If it's a large tumor, you may have to centrally debulk the tumor in order to maintain that dissection plane, and maintain visualization. And that is very key, I think. We've really tried to avoid blind dissection, like as you should in all skull base surgery. So, let me start off with a case. This is a case of a 37 year old female with acromegaly. You can see her IGF-1 is elevated with a z score 3.3. And she has a macroadenoma that is fairly large, just as a little bit of chiasmatic compression, but she really had no visual field deficits. And the sella is a pre sella, which is fine for this approach. So, what I'm gonna do is, I'm gonna break this down into those eight steps. For this case, you'll see the background in white, and then for each step, I may introduce some video from other patients, and it will be a blue background, so you're not confused. But I like to start off first with a wide sphenoidotomy. So, this is what I expect to see when the head and neck surgeon is done. And the reason is that you need a sphenoidotomy that allows you to have your endoscope coming in, where you can see what you're doing. So if you come in and all you see is this, and this is basically traditional microscope-based neurosurgery, is this is the only opening visualization that you get. And I will say that I seen this at other locations where they do give you access to the sella, but this will not allow you, I think, at least in my hands, to do this procedure. And the reason is, is that you need space for the endoscope to come in here. And this is your endoscope, that you can't be sword, what we call sword fighting. And you need, you have two instruments. You have a suction in the same there as the endoscope, and then your other instruments. And when you're working in the sphenoid sinus, your endoscope is gonna be part, up here, further back, not that close. You need a wide opening because your dissection largely is going to be around here. And if your opening is only right here, your endoscope's gonna end up here, and you're just gonna be clashing with all your instruments. So, you need a wide sphenoid opening. And once you have a wide sphenoid opening, this allows you to actually have the endoscope in the sphenoid sinus. And here's a closeup view where you're, now you can see where the instruments are getting very close to the endoscope, but again, we're gonna be working here in the gutters, and you need all this wide open space in order to accomplish this procedure. So, bimanual dissection with dynamic visualization. So, pituitary surgery, I think is microneurosurgery. And this is our case, and this is the end of the case. I'm not gonna show this at the end, but this is now exploring, and you can see here, I'm using Rhoton instruments. And here's, Dr. Wang is following me with the endoscope, and I'm unable to do the 45 degree endoscope, visualize the complete resection. And you need two hands to do this. I can't stress over and over how important it is to avoid blind surgery. So, putting a curette and trying to scoop a pseudocapsule blindly, posteriorly, will very often, either rupture the pseudocapsule, or you may injure the posterior gland. The dynamic endoscopy gives you a better sense of depth, and perhaps more of a 3D visualization as well. So, a wide sellar dural exposure and meticulous dural opening. Similar to this sphenoidotomy, what you need here is to be able to visualize the gutters. So, I always open to the four blues. You want to see the medial cavernous sinus and the cavernous sinus, actually, when you're doing this dissection, in nearly, in all cases, there's an inflection point where the cavernous sinus actually come, the dura comes back at you. And you need to get to this point bilaterally. Unless it's a small tumor, but this is a talk of macroadenoma. So, this is what we do with every single case. I do open up high. I don't take the tuberculum sella. That's really not necessary. And I come low here on, over the clivus. And I usually want to make sure that I can see with a zero degree scope, along the floor of the sella, but I'm not too aggressive because I do want to leave at least some bone there in case it's necessary for reconstruction. So again, wide sellar opening to the cavernous sinuses, because as you're doing this dissection, you're gonna to need to pull that medial cavernous sinus wall over in order to visualize that dissection plane, particularly on the side of the gland, or opposite to where the gland is. And I believe this is a video here showing the beginning of the dural opening. Those little marks you see there, this is what I do often for the residents. I'll make the openings near the carotid, where I insinuate first, make sure it's safe, and then let them do the more medial part until they're more advanced and have their skills higher. But I will often, or sometimes spend up to 25 minutes with the dural opening. And what I tell my residents is, pretend this is the spinal cord, and that you don't want to injure the underlying cord. And you have to be that meticulous with the dura opening because at the end, you want an intact gland capsule here. And so, we spend a lot of time making this dural opening, it's not how I was taught. That we used to just take the knife and open it up because it basically, when you do that, pituitary tumor spills out, and you would start your intracapsular resection, as I was taught in training. But at Ed Oldfield expressed the high importance of maintaining an intact gland capsule when you begin. Now, this part here, actually took me a while to understand and think about the relationship with the tumor to the surrounding structures. And maybe obvious, but here we are at that same point. And I always ask the resident, what are you looking at here? And the answer is, you're looking at gland capsule. This is all gland capsule, everything you see here, but if you look very carefully, you can see how there's a difference. And if you look at the vascular pattern, you can see that this basically is gland here, very, very thin gland. And even though there's a very thin, thin gland here, it's to the point where it's almost transparent and you can see the tumor behind it. But indeed, if you have opened the dura carefully, that you're looking completely at gland capsule. And I think this is just very important to the success of this procedure, not critical, but it helps you get started. Now, if you look at the MRI scan, and here's in sagittal, the gland enhances around the tumor and here, like in most cases, it's a post-fixed stalk. We have to be very careful when the stalk is anterior, because when you take out a large macroadenoma, it can drop all the way down here, and you can actually have pituitary insufficiency, But I'm not going to show a case like that today. But for this case, I don't think this gland here is viable, probably just by some minimal cells involved here, because I know the bulk of the gland is all posterior here. And so, but I do know that I'm looking at gland here. As I've mentioned, I would call this a post-fixed gland and there's a stalk. And you're looking at the anterior gland around it. Now, above that gland is the diaphragma sella. So, the diaphragma sella extends over here, just an . And then, there's the notch here where the dorsum sella used to be. And as, I think you all know the reason why suprasellar components of the pituitary tumor are dome-shaped, is because it's attached here, attached here. And as the tumor goes up, it's usually like a herniation anteriorly. And it always looks like a dome because you have two attachment points. And the only shape that it can form is a dome shape. Posteriorly, there's the posterior gland. I did not show you a scan with the posterior gland, but I bring this up because as you're doing a pseudocapsular resection, you are, you must think what you're going to see here. That there's going to be, as the diaphragma drops, there should be a gland, portion of gland over the diaphragma, except possibly anteriorly if there's a herniation, a defect, that's like a hernia where it's just arachnoid over that. But if you're doing this dissection and you are on the outside capsule, the gland, you can do hypophysectomy, if you're not aware of this. Now, the other point here is that the arachnoid from the anterior cranial fossa, dips down and attaches to the gland capsule anteriorly. And that would be right up here, is where if you go up too high, and so when you're dissecting the dura superiorly, if you just blindly do that, or you stretch it too far, you're get a CSF leak very early in the case, with a wide exposure. Now, this is something that's a bit perhaps unique to endoscopic surgery, and that for most microscopic surgery, you're only opening, most people do is rather limited. And you're never really up here in this area, because if you just use curettes and scoop out tumor in an intracapsular fashion, you don't have to worry about CSF leaks up here, but if you do a wide dural opening, you do have to worry about that. And I'll get to that in one second, how we try to avoid CSF leaks. The other component is to look at the coronal imaging very carefully. If you look at where the gland is, in most cases, it'll be on one side or the other. And again, you can always see almost in all cases, the enhancing gland and the hypo enhancing tumor within it. So, the body of the gland, and this is why I call a pearl here, and is that the body of the gland will be displaced contralateral to the side of the potential cavernous sinus involvement. So, here's a different patient. So, you may be staring at this and wondering why is this invading the cavernous sinus? If you're thinking about that on this side, you're gonna find the gland on the contralateral side. So, the majority of this gland will be on the contralateral side. I think that's important for a pseudocapsular resection because, and I well, I'll explain is, you want to start your dissection right here. Do you want to find the gland right off the bat? And you start on the ipsilateral side to where the gland is. So you, number five is to begin sharply incising the gland capsule. So, and back to our patient, as I said, my plan is to sacrifice this part of the gland because it's, I don't think it's a functional portion. And I'm gonna make an incision here, so this superior incision is very, very important. If you don't make this superior incision, it's a very fine cut to the gland capsule. If you start doing a pseudocapsular dissection, and you haven't disconnected this part of the gland capsule from the pseudocapsule, this part, you'll, as you're manipulating the tumor, will be brought down and you'll get a CSF leak right up here, because you're gonna tear the arachnoid as it's coming down. But if you make this incision, and you free it up, then you can maintain the integrity of the arachnoid superiorly. So, here's our case. I've already made the incision on the right side. And here's that transfer superior incision that is very important. And you can see how fine the incision here, so this isn't sizing the gland capsule, it's not something that I was ever taught during training to think of it this way, I would just, would've opened up right here and started resecting tumor from the beginning. But we're gonna try to find the pseudocapsule, and to do so in a methodical way, you incise the gland capsule first. For cases where the gland is clearly on one side, I'll just start on the ipsilateral side to the gland first. Okay, I get the next slide, please? Thank you. This is a different patient. Just to show you an example of that anterior fossa arachnoid, that here's the gland capsule, and here is that arachnoid attached to it, that this is one with a dissection that it came down, and just showing you that relationship, or right here that this is a picture that you want to avoid getting because if you do so, then you'll have to deal with a CSF leak afterwards. So now comes the more technical parts. So if you set yourself up for success with a wide sphenoidotomy, a wide sellar opening, a meticulous dural opening, and then you open the gland capsule. The next part is finding the pseudocapsule and that plane between the pseudocapsule, and the normal gland. As I mentioned before, I start on the same side of the gland. So, this is four different cases where I would identify, here's the gland here. Again, this part is, there's a, there's some question of, there's, the gland is so thin here, and you can see a very thin margin of gland remaining here, and same thing here, a little bit of cavernous sinus encroachment there. And therefore, I know I'm gonna find the gland on the contralateral side. And this is where I always start the dissection in all these cases to find the pseudocapsule. So, same place we were, here's the gland capsule that was freed up. And we are now identifying, here's the tumor, the pseudocapsule. This is gland, you can see, almost looks like liver in its formation right here, where you find that plane between the two. This is a Rhoton 3 that I'm using, and suction in the left hand. And I, you, it's in most cases where you're gonna be successful, it's actually a relatively easy to find that capsule of that plane between the pseudocapsule and the normal gland. The gland has a different color. The pseudocapsule is grayish here. And there's a clear distinction here. They're going over the superior margin right there. Again, visualizing everything is, as you watch that clip, there was no point where there was any blind dissection. Next slide, please. So, pearl. The pseudocapsule is, has this grayish issue typically. And the gland is yellow pink. And this is what you, what I look for. And when it's, when you find it, it's so obvious that you're on the right plane. Also, the pseudocapsule's rather robust. As proposed by Oldfield, it's actually a layer of collagen, and it can be retracted with a suction. It could retracted with Cottonoids. If you find that you can't retract it, so it's soft, you probably in the wrong plane in your intracapsular. Conversely, if it's rubbery, and you're not able to advance the dissection plane, you're probably within the gland itself, and not at that proper plane between the pseudocapsule and the gland. I would just want to reemphasize that the pseudocapsule is robust. You can retract it, you can even pull on it. And then you know that you're really dealing with the pseudocapsule. So, here's our patient, again. Here, I have a Decker forceps, and you can see that the grayish pseudocapsule here, and I'm literally grabbing it and pulling it. And I'm using the suction. Now, as the dissector, here's gland with the diaphragma behind it. Pseudocapsule, this is all gland right here. And we're working our way over here, where we may find a very thin layer of gland in the medial cavernous sinus wall. So, as I mentioned, if it's too soft, you're in, you're probably in the wrong layer here. So, here's a case where I'm dissecting, and you can see the suction is basically sucking away my tumor mass. And I thought, well, I made another incision in the gland there, and there's a pseudocapsule. You can see it's that grayish color. The gland is pink. And I re-established the correct plane. And now, you can see, I can retract on that pseudocapsule. And this is all gland. This is pseudocapsule. This is a Cottonoid. I would not be able to do this when I was intracapsular. And so, I will routinely do this. I'll make other decisions to find the pseudocapsule. This is a little bit more of a extreme example, you can see, has a large macroadenoma. If we could play the video, please? You can see the, it has a large macroadenoma, and just how tough the pseudocapsule is. I'm really pulling on it quite vigorously out there, I have a Cottonoid. I'm grabbing it, and you can't grab tumor tissue per se this way, it'll just come out. As you know, it's usually suctionable. And this is just showing an example of what you can do with a pseudocapsule that's quite robust. And the fact is, large pituitary tumors, actually the pseudocapsule there is probably the thickest and most developed of all. Next slide, please. So if you are having challenges and you can't maintain visualization, you can just debulk it. I will incise the gland capsule or the pseudocapsule, and then essentially debulk it, but I don't try to do so to the pseudocapsule. I try to leave a little bit of tumor behind, and but I think it's just best, this is a skull base surgery, and think of it as of a meningioma. And here, I was having some challenges. So, I just made an internal incision here, debulked. And then, once I was able to do that, I was able then to retract this mass and re-established a plane, and come around and complete the dissection. Next slide, please. So, I think this is very key, and perhaps where it gets the most technically difficult, is maintaining visualization of the dissection plane. And avoiding the temptation to do blind dissection. And what it requires is a hand over hand technique or the use of Cottonoids, or, so here, I put a Cottonoid in, just like you may with other tumors. And working with your co-surgeon to maintain visualization. You know, we endoscopists always show the best part of the videos, and we don't show the part where you have sewing in the endoscope. And I just don't work during those portions, but I wanna maintain that plane because I know the posterior gland is gonna be behind here somewhere. And in almost all cases, you can identify with macroadenomas, you can see it, and you can continue to this dissection until the tumor is completely out. Next slide, please. Now, here's a different patient. And just to show you some, there's a large macroadenoma, and where, here's that the diaphragms is right here. Here's a pseudocapsule. And this dissection is not a blind dissection. I'm using the Rhoton instrument and the endoscope to continuously maintain that dissection plane, that visualization, and continue the dissection. So, to complete the resection of the tumor just the way you would like to, without putting any instruments in blindly. So, one of the things to avoid, at least in my experience, is hemostatic agents of these gel foam products. Because you can obscure this dissection plane. I kind of work in a, maybe a little bit of a pool of blood, by using the suction to maintain visualization. If you have bleeding from the cavernous sinus, obviously you need to stop that with one of these agents. But I don't use it regularly until the tumor's out. And then I do so for hemostasis. So, this is our case, and I used the curette here just for one spot in the corner, but you can see here that there's a little bit of a pool of blood back here. I haven't cleaned it up because again, with suction, you just, you can see that your planes, and then once you've freed up the tumor completely, you can then explore. And once you feel that you've got a complete resection, then you can get permanent hemostasis. But I would really advise against using a gel foam. You normally need to use it here, and you can use it in these corners because of the wide dura opening. Once the tumor starts coming out, almost invariably bleeds from the corners here, and you need to get hemostasis, but I don't use it in the resection cavity, unless there's really a large volume of blood loss, which I'd rather avoid the transfusion. Next slide, please. So, our patient did well. She was discharged on postop day one, and she's now five years out, and she has normal pituitary function, and normal lab values. And you can see the postoperative image where the normal gland was maintained. And then, there's tumors removed with a pseudocapsular resection. So, I'm gonna now show another case. And this is a case of a non-functional tumor. Again, looking at this, studying at a very favorable sphenoid sinus anatomy here, here is a little bit of the question of cavernous sinus involvement, and therefore, you know that the gland's gonna be on the contralateral side. So, looking at the images, the gland is here, we're going to start our dissection here. It's gonna be a very wide sellar opening from here to here. In order to do this, to accomplish this, just to see all these planes here and here, we need to do all the steps that I described before. So the were all chopped up for instructional purposes, but here's a case kind of from start to finish without interrupting. It has been edited, as you can see, but you recognize, here's the gland. Actually, all of this is gland over here. I made the incision. I've made the incision superiorly across the transverse incision superiorly. And now, finding that pseudocapsular plane. Again, the pseudocapsular's gray, you can see the obvious gland on the patient's right side, maintaining complete visualization. And the only way this is possible is the scope up close due to the wide sphenoidotomy that were obtained. And it's this hand over hand technique, maintaining visualization at all time. And you'll see the diaphragma coming down posteriorly, and you just have to maintain that visualization inferiorly. Sometimes it's quite stuck inferiorly, you can be much more aggressive on the inferior dissection plane. And when you're done, when, I hope you experience the same thing that I do that, now there's many people, and the operating room nurses who literally applaud when they see a tumor come out unblocked for a pituitary surgery, because they had never seen that before. And it's a very gratifying operation when you're able to accomplish this. I always go through at the very end, explore the capsule very carefully. If you see any little strands of, looks like collagenous material, I'll just pull them off and get a excellent result. And I'll stop there. I hope this was informative for everyone.

- Marvin, thank you again for a spectacular talk. Very revealing, very informative. God bless Dr. Oldfield. He was a true master surgeon when it came to resection of pituitary tumors. Huge contribution there, huge contribution from you. Some of the challenges that I have faced with these pseudocapsular resection is, these giant tumors or very large tumors, it's extremely difficult to use the pseudocapsular method. It's, you have to do fair amount of debulking. And by the time you're sort of, have lost a lot of planes. Can you tell me that based on the videos I see, it seems like this is an excellent technique for a small to medium, to maybe somewhat of a large tumor, but for a large, large tumor or a giant tumor, do you think a pseudocapsular resection is fairly possible?

- Yeah, that's a great question there. And the answer is, it is possible, but you're right. I think, you know that giant tumors, by the time they get giant, they're often invasive. And again, I don't think this technique is really applicable to tumors that are in the cavernous sinus. And you can do many parts of the pseudocapsular resection, but you know, it's really not a practical, to think that you can remove all of it. But as I mentioned, I've actually been quite surprised that the very large tumors, they actually invoke, I think some type of desmoplastic changes around them. And if you can find the normal gland, you actually can resect them. And I think I was showing some rather large ones. So, try it once. I think there's other issues that make it more difficult but actually, I've maybe perhaps ironic or paradoxical, I actually have more challenges with very small tumors. Actually, the Cushing's tumors. Because if you really believe what Ed Oldfield teaches, you would wonder why would a small tumor even form a pseudocapsule? You'd think it would form by a large mass compressing tumor cells, and why would a three millimeter tumor even have a pseudocapsule? I think the answer is that a firm tumor, you can just remove with the same technique, but I approach every tumor with this idea of finding the pseudocapsule, regardless of the size of the tumor. And if you believe it's there, if you believe it, you'll often find it. And I think that was the, I didn't believe it until all that field came and acted as a coach. And since then, I've been, you know, a true believer because it really is such a gratifying procedure when you're able to find it.

- Now that is very true. I think it's a very elegant way to do pituitary surgery. There is no doubt about it. It is the right way to do it. It's a lot more challenging, just like you mentioned. And I agree with you. They're very small tumors, and very giant ones are the ones where the challenge resides. It's the functioning tumors that are about a centimeter or so, this is a perfect technique or bigger. I think for Cushing, for acromegaly, if you can get a pseudocapsular resection about a centimeter or so, or bigger, the outcomes is significantly better.

- Yeah. We have a faculty member who came from, who trained at Virginia when Ed Oldfield went to Virginia. And he had a very interesting observation, is that when he was able to accomplish it for Cushing's disease, the cortisol levels dropped much faster than when he was not able to accomplish it. And I think we found the same thing that if you're able to resect the tumor, we've looked at our growth hormone levels the day after surgery, our prolactin levels, they're significantly lower the day after surgery when you accomplish the pseudocapsular resection. So, I think there's also some physiology there that, I don't know what it is about it, but it results in a much faster remission rate.

- I agree with you. To be honest with you, so much of pituitary surgeons, and so many of them have focused on how to get there, rather than what to do when you're there. And this lecture is such an extremely good example of it doesn't matter how you get there. It's about what you do right when you're there. It really, the outcomes are dependent on that. We can sit down and talk about endoscopy sublabial, you know, a transseptal technique and say mine is better than yours. I don't think that's the essence. The essence is, when you were there, how are you gonna do the good job to really manage the pathology? And Oldfield was a classic example. And sublabial approach worked very well for him. He was very comfortable, and his results were excellent. Nobody can question, well, look at Dr. Oldfield, he did a sublabial, just archaic way to do it. That's really focusing the attention completely on the wrong part of the puzzle. The puzzle is, what you're gonna do when you get there. Are you gonna remove the tumor effectively to provide a good cure for a patient with Cushing's disease or acromegaly? Both of those are life-threatening and long-term, can be devastating, chronic diseases. And I think something that I emphasize that is so extremely important is the number one cause for subtotal resection, no matter which way you go, if you do the pseudocapsular resection or not, is inadequate bone removal, inadequate exposure of the gland, inadequate dural opening, and just lack of visualization, and just putting your ring curette blindly in there, and hoping for the best that you're gonna get something out. And if you get very aggressive, usually you'll get a CSF leak, or thanks God occasion, you're just gonna injure a perforator and have a much bigger problem. So, no matter what exposure we use, which I would love to be able to do pseudocapsular, just like you're doing more often, is you gotta have a great exposure, you gotta have a very good dural opening. You've gotta be able to understand anatomy of the gland, and you gotta be able to follow the planes very carefully. Do you have any other pearls of technique that you can add on?

- I can't agree with you more. I think that's very wise. A little bit about endoscopy versus microscopic. I will say that working with a team, and particularly if you can team up with someone that you work with a lot makes a big difference. Many of these procedures, as you said, it doesn't, it's a little, that the actual instrument that you use may not make a difference. But if you believe in outliers of, you need to do something 10,000 times to be a perfectionist. My recommendation is, if you're going to do this well, that you work with a team member that, I mean, the contribution of Dr. Wang, I can't mention enough. She's someone that, you know, after you've done a thousand cases together, she's so comfortable. Marvin, why don't you do this? Or, she's another set of eyes. And you become one. And even though two members may not be necessary for the simple cases, it's important for the difficult cases. But I think if it's just that component of skull base surgery, for me, makes a big difference. Sometimes if I have to work with someone else, I struggle because they can't maintain the same visualization. I often have to widen the sphenoidotomy myself. And so, I would really encourage everyone to find a team member that is very good, and you work with. And do it over and over and over again to develop the skills. And you'll find that success.

- I cannot agree with you more. I always say that endoscopic surgery is like a dance. It truly takes two to tango. And it takes years for two of neurosurgeon, and the rhinologist to be able to learn how to work together, to be able to essentially foresee each move before it happens, and make both of them to be able to create the final performance, which is so critical for the good outcome With that in mind, I want to truly thank you for letting us know about your great pearls of technique, Marvin, you're a truly master surgeon. I have had tremendous respect, follow your career. And technically, one of the best surgeons I've seen at work. And it's really truly an honor to have you with us, and hopefully we can have you with us in the near future.

- That would be very nice. And thank you for your words. Not sure they're so deserved, but I really appreciate it. Thank you, Aaron.

- You're welcome. Have a good afternoon.

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