Grand Rounds-Endoscopic Skull Base Surgery: Transtubercular, Transethmoidal and Transcavernous Appro

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- Hello ladies and gentlemen and thank you for joining us for another session of the . We're privileged to have back with us again, Dr. Ted Schwartz from Cornell University Medical Center who will be talking to us about endoscopic approaches to skull based tumors. Ted, thank you.

- Aaron, thanks so much for having me. So today we're going to go over all of the anterior, endoscopic skull-based approaches, the endonasal skull-based approaches. I'm gonna talk a little bit about how we divide these approaches up and then I'm gonna give you examples of each of the different approaches that have been developed and the types of pathology that we can treat with each of these approaches. So I work out of the Cornell New York-Presbyterian Hospital at the Institute for Minimally Invasive Skull Base and Pituitary Surgery. And the reason that we've developed these approaches is to try to avoid what you see here on the screen, which is the approach to the suprasellar cistern, as an example of a transcranial approach that tries to reach pathology that's underneath critical neurovascular structures such as, in this situation, the optic nerve and the carotid artery. And in this example from a textbook, you can see that the surgeon is trying to get to pathology underneath the optic nerve and underneath the carotid artery and has to work through lots of small corridors in order to avoid damaging any of the important anatomy to try to get to the abnormal anatomy. So in this example, also from another textbook of a craniotomy, the surgeon is trying to take out a craniopharyngioma. And what you see is not as much the craniopharyngioma, which is barely visible through these narrow windows but you see the optic nerves and the carotid artery and the third nerve. And the pathology that you're trying to resect is barely visible through the standard transcranial or anterior approaches. The way we get to the sort of more anterior skull base around the ethmoids has traditionally been an anterior craniofacial approach. And with this approach, we have to make bi-coronal skin incision and often there's a facial incision as well. And the point is to get to this area of the ethmoids and to remove this box of bone and sinuses in frontal sinus. And these are examples of these traditional approaches but the issue and some of the problems can be faced based on all of this brain retraction, you can see there's a retraction on the brain here, and there's quite a bit of brain retraction and that can be damaging to the cortex. The standard transsphenoidal approach that is often performed, involves a small incision in the nose or a super, sorry sub-label incision. And with this approach, you have to retract up the mucosa and work underneath the mucosa, and then dissect on the mucosa and remove the perpendicular spine in order to get a retractor in. And the traditional two retract are used for standard microscope based transsphenoidal surgery has been the Hardy retractor. And one of the limits of the Hardy retractor, as you can see here in this example, is that the view laterally to the tube of the retractor is somewhat limited. So when you get down to the depths, you really can't see past the retractor edges. Other approaches to this area that have been developed are transfacial approaches. And obviously these are cosmetically quite disfiguring and often require complex closures that are done by the plastic surgeons. And if you look at the area that's exposed by this approach, it's really just the cell of the clivus and the optic nerves. And I'll show you how we can get to these areas and more using endonasal endoscopic approaches. Here's another traditional approach, the transmaxillary-LeFort 1 And in this approach, the maxilla is actually fractured and removed in order to get retractors in. And if you can see where this approach is getting you, it says area exposed by the LeFort 1 is really the clivus and the sphenoid sinus and again, I'll show you how we can get to these areas through a minimal access, but maximally aggressive approach, namely the endonasal endoscopic approaches. So this is what we're trying to avoid are these larger tractors and large corridors. So their advantage to the endoscope, and this is another image from another textbook. And the real advantage is, is in this basic principle. And the basic principle is that with a microscope, your lens and your light source are outside of a narrow tube. In some situations, it can be your Hardy retractor and others It's the mouth or the transcranial corridor. And when you have your lens and your light sources outside of a tube, then you can only see a small amount of Mr. Tumors head here, but when you can advance the lens and the light source to the end of the tube, well then suddenly you can see around the corners and you can see not just Mr. Tumor's head and his ears, but much more than that. This is an example of one of my fellows took of the trepidation. One might fear using an endoscope and what you see with a microscope, looking through this tunnel in central park, on here's a child is afraid to go in, but when you use an endoscope and you pass it through the tunnel, then suddenly you get a very wide field of view. Now it turns out there's a little bit of distortion, a little bit of a fish mouth look, and this is an example of that, but you get used to it very easily. And in fact, it allows you to see a little bit more around the edges than you otherwise would. And when we do our endonasal skull-based surgery, we use a scope holder and that's just our bias and our preference. Some people like to take the scope off a scope holder and actually have an assistant hold the scope. And there are some advantages to that. Some people feel it gets you better 3D view because the eye is moving in and out. But in my opinion, I like to have my eye very, very steady when I operate. And we will take the scope off the scope holder and particularly angled scopes and advance them into our cavity and look around. But a lot of the surgery you can do with a zero degree scope or a 30 degree scope on a scope holder and having it fixed can be an advantage. A lot of our surgeries look like this. We'll have the scope in one nostril, and it's usually for a right-handed surgeon. Our preference is to put the scope in the patient's left nostril and we'll operate through the patient's right nostril. Now, when you're working away from yourself, that's a great angle of approach towards the other side of the head But when you want to work towards the patient's right, towards your belly, what I'll often do is I'll take the endoscope and I'll elevate it in the nose, and I'll put my hand in the other nostril and then I'll triangulate down. And that allows you to work more in this direction, towards the left side of the patient's head. We do a bi-nostril approach always. We don't use one nostril, even for small tumors. We like to make a big opening and I'll go over some of that approach and to do the bilateral approach again, I've borrowed these from someone else. And I want to give credit. We take out the back of the septum and work bilaterally through both nostrils in order to take out tumors. So this is an example of working through both nostrils. In this situation, we actually have two surgeons and it's possible to get up to four instruments in through a transsphenoidal even endonasal endoscopic approach, four instruments and a endoscope. Now in our surgeries, we use Intrathecal fluorescein for a hundred percent of our cases. And a lot of people ask me why we do that. And there are a couple of reasons. The first is that when you give fluorescein if you have a small tumor, then it allows you to see if there's a leak or not. And sometimes CSF is clear and be hard to see. And when you use fluorescein, you absolutely are sure if there's a leak and if there's a leak, you need to fix it. So I think it decreases our rate of post op CSF leak. when we do our big extended cases and we're clearly going intercranial, then we know there's going to be a leak, but at the end of the operation, when we're done with our closure and we'll go over how we do that closure, we want to be sure that there's no CSF leak at the end of the operation, that we have a good water-tight seal. And having the fluorescein in there is really helpful. Now, there have been some questions about safety of intrathecal fluorescein and it's an off-label use And we have published on the safety of this and now have done it in over 450 cases and not had any problems. So if you do it correctly and give a small amount and pre-treat with Decadron and Benadryl, patients can tolerate it very nicely. And this is that publication. So there are arguments for, and arguments against endonasal surgery And I'm going to go over some of those arguments and we'll address them during the course of this lecture. So in my opinion, you get a better view than the endonasal surgery. And we've discussed why that is. I think it's very important to advance your light and your lens to the depth of the cavity in order to see around. It's the most direct route to the pathology. It's easier to remove tumors in the medial optic canals, believe it or not. There's a lot of people who criticize endonasal surgery saying you can't take out tumor in the optic canals, but actually you can, and I'll show you how we do that. You don't have to work between critical neurovascular structures as much you do somewhat, but because it's a direct ventral approach for the most part, most of those vascular structures and nerves are on the distal end of your surgery. There's no brain retraction, which is a great advantage. And you have improved access to the medial Cavernous sinus. The cranial nerves are lateral in the cavernous sinus. So this can be a great approach to the NIGO cavernous sinus, because if you go transcranially, you often have to deal with the cranial nerves because they're in your trajectory. Whereas if you go from a medial to lateral approach, the pathology is often pushed the carotid artery and push the cranial nerves lateral So that they're not in your way. And I'll show you examples of that. And of course there is improved cosmesis. So on the other hand, there are arguments against endonasal surgery. Some people feel that the view is actually limited, that there's limited maneuverability through the nose, that you can't remove giant tumors through the nose. You can't remove meningiomas in the optic canals. You can't remove meningiomas encasing vessels. Some have said, you have to pull on tumors, which risks damaging blood vessels attached to the back of the tumor. You can't chase a dura tail. Why operate through an infected field When you can operate through a clean field? You can't preserve the pituitary stock and the risk of CSF leak is too high. So I'll address each one of these criticisms in turn and show you how, in my opinion, and our experience that these are not the case. So what are the indications for a endonasal skull-based surgery? Well, of course, pituitary Adenomas and pituitary carcinomas. In addition, we can take out craniopharyngiomas even large third ventricular craniopharyngiomas above a normal size sellar Rathke Cleft Cyst. clival tumors, such as chordomas and Chondrosarcomas are a great indications for this. Meningiomas of the tuberculum sellar, Planum Spehnoidale, Olfactory Groove, and potentially Petroclival a little bit. That's more controversial. Esthesioneuroblastomas can be treated this way. Juvenile Angiofibromas, Sinus Tumors, such as Osteoma, Papilloma and schwannomas and of course, CSF leaks such as Meningoencephalocele and Encephalocoele which traditionally were treated with bicoronal craniotomies and bicoronal flap. We now treat completely through the nose, through an endonasal approach. Now, the key to all these indications is case selection. And I'll talk a little bit about which cases are appropriate and which are not appropriate for endoscopic endonasal surgery. But I think some of the criticisms come from choosing cases that may not be appropriate for this approach. So we divide our approaches into several sub categories and the way that this categorization system evolved was through my dialogue with my Otolaryngologists, Dr. VJ Anand and we would try to figure out how to communicate about what kind of case we were gonna do. So I like to think about the skull base approaches as involving a target where you're going, involving a corridor, how do we get there? And that corridor is usually a sinus that we have to broach or two sinuses in order to get where we want to get. And the approach is really the intermediary between the target and the corridor. And we have a system that we put together and we wrote a paper on it, and I'm going to go over that now. So therefore endonasal corridors in our system, and the first is transnasal, and yes, they're all transnasal, but the transnasal corridor means that you don't have to go through any sinus. And you can actually go down to the odontoid and take part of the clivus just going through the nose without breaching any sinuses whatsoever. The transsphenoidal Corridor's the one we mainly use. The transethmoidal corridor goes with the ethmoids and the transmaxillary corridor goes through the maxillary sinuses. So these are the targets that we can reach. We can go all the way from the cribriform plate to the anterior fossa to the planum tuberculum, sellar lateral cavernous sinus, medial cavernous sinus, lateral spheroid sinus down to the clivus, all the way to the odontoid. And then laterally, we can go, into the pterygopalatine fossa on the back of the maxilla, the infratemporal fossa, the Petrous Apex and the infratemporal fossa. So there's quite a large area of the midline and para midline skull-base that we can reach. So these are all the approaches that we've defined through the Corridors, Transsphenoidal Transnasal, Transethmoidal, Transmaxillary, and these are the different approaches that allow us to reach all the targets over on the right side. And I'm going to Transsphenoidal corridor is really the most popular, the corridor that we most often use. And it gives us the most room when going into the skull basin. The transsphenoidal corridor gets us through the planum tuberculum, sellar, cavernous sinus, and lateral sphenoid sinus. Of course, the standard most commonly used of these approaches is the Transsphenoidal Transsellar approach, which is good for pituitary adenomas of all different shapes and sizes such as shown in this slide. This is an example of the Transsphenoidal Transsellar approach, and the approach basically involves moving lateral to the septum, middle to the middle turbinate. The colon is identified below, and as you move up past the middle turbinate, you see the superior turbinate and the ostium to this sphenoid sinus is just behind the superior turbinate. And it's about a third of the way down. So when you do open up the ostium, you want to go more inferiorly than superiorly. If we're not harvesting a nasal septal flap, we open up the ostia bilaterally. And the back of the septum as mentioned before in order to create a large open cavity. And this is the view you get of the carotid Prominence is the sellar, the clivus. We can look up and laterally and see the optic prominence, the carotid artery within its canal, the carotid prominence and the optic-carotid recess, which eventually if you keep following, it becomes the anterior clinoid. If we look above the sellar, you see the tuberculum sellar on the Planum sphenoidale and this would be a standard opening to take out a pituitary tumor. And these are just some of our pituitary publications. So the real advantage of the endoscope is for lateral visualization. And I think is a real advantage to see into the medial cavernous sinus and to see suprasellar residual tumor. You know what I think, I think they're supposed to be movies there.

- Yeah, We have it for you.

- Let's go to the first movie. So this is just a resection of a pituitary adenomas. And in this situation, I want to point out a couple of the highlights, which are that we try to take the tumor out on block. We try to preserve a plane... I'm introducing you now to what it looks like to see the fluorescein coming above the normal pituitary gland. But as you can see, once we've taken out the majority of the tumor, we will advance an angled endoscope. And we're looking out with a 30 degree scope up into the bottom of the pituitary gland and peeling off residual tumor That's left at the bottom of the pituitary gland. You can see us getting out all of the last bit of the tumor with an angled scope. This is a view that's hard to get with a microscope because you're not able to advance it into the cavity and look around the corners And clearly there's a CSF leak here. So we would harvest fat and put fat and a piece of MEDPOR within the sellar. And then we close with some DuraSeal. So let's go back to the talk. Now for lateral visualization, I'll show a quick example of why it's such a huge advantage to have an endoscope to look up as that sellar descends. Can we go to the second movie? So in this example of a pituitary tumor that's been removed, the diaphragm has descended down and when we originally is zero degree scope, we thought we got everything out, but then we used an angle endoscope, looked up into the corners and sure enough, there was some residual tumor that was lying up in that gutter, that lateral gutter next to the descended diaphragm. And actually there was quite a bit of tumor there. So the endoscope is really nice for getting out that residual tumor and seeing where that residual tumor is. But let's move on past pituitary tumors and go to some extended approaches. So the extended approach that we use most commonly is the Transplanum, Transtuberculum approach. And this is an approach that's very good for Planum Spehnoidale meningiomas, tuberculum sellar meningiomas and these tend to be pre-Chiasmal. And also for Craniopharyngioma, they tend to be retro Chiasmal and Rathke Cleft Cyst. So this is just some publications on that topic. When we do this approach, we often use a 30 degree scope cause with a zero degree scope, your angle would be such that you'd have to remove a lot of the planum and even Krupa form plate to see where you need to see But with a 30 degree scope, you can look up either in front of or behind the chiasmal and remove less bone, which of course makes your closure easier. So this is the relevant anatomy. For this approach, We often just take the very top of the sellar, just a little bit, the tuberculum and the Planum sphenoidale. This is the medial optical carotid recess, which is the middle carotid if you're coming from above. This is the lateral optical carotid recess, which is the inter carotid If you're coming from above and a post carotid would actually be up here behind the sellar And you can remove that by following the Clavis up extra duraly. And this is the relevant anatomy you'd see behind the bone. So for this approach, we do this kind of bone opening. And then of course, we also can open up the medial optic canals, and it is not difficult to open up the medial optic canals. They're right there sitting in front of you. And there's a very thin layer of bone And the bony canal is often easily visible. Now, one piece of anatomy we have to deal with is the superior inter cavernous sinus. And this is a vein that extends between the two cavernous sinuses and this needs to be cauterized and cut If we're going to go and do a suprasellar approach. So this would then be the dura opening that we would do. Now we can work pre-chiasmal, retro-chiasmal, or we can use work actually Retro-Sellar. And I'll show you examples of how we work just behind the pituitary gland and get around that issue. So for this extended approach, here's the superior cavernous sinus. You can see in this patient that it's a fairly significant vascular structure. This is the sellar. We've opened up just the top of the Sellar. And then this is the tuberculum is probably about here. And then this is some of the planum that we've opened up. Once you remove the bone and open the dural, you see the pituitary gland, the optic Chiasm the optic nerve and the arachnoid. If you open up the arachnoid, you can see the gyrus rectus, the anterior cerebral arteries, the optic chiasm. Here's a craniopharyngioma that's sitting in the prepontine cistern just below the optic chiasm. Now, a great view you get from below for these craniopharyngiomas is this view into the third ventricle, because the craniopharyngiomas will often extend behind the chiasm and they'll be stuck to the floor of the third ventricle, and there'll be stuck to the back of the chiasm. Then once you take them off, you get this beautiful view of the fornix, the frame of the Monroe and the choroid plexus. Now for meningiomas that are pre-chiasmal, I mentioned before, it's important to unroof the optic canals. And this is an example of that. So what you see here is the optic chiasm. This is the the lamina terminalis, the A1, ACOM, A2, the gyrus rectus. This is the optic nerve. And here you can see that the optic canal has been opened within sphenoid sinus in order to take out tumor in the medial optic canals Cause sometimes these tumors will invade into the medial optic canals and we've done that bilaterally in this situation. This transplanum transtuberculum approach is very good for planum meningiomas, tuberculum meningiomas, pituitary adenomas that extend anteriorly. This would be very difficult to take out just by opening the sellar. You really have to take out the planum to get this part removed, Rathke cleft cysts and of course craniopharyngiomas. So this was a patient that I saw where I was told it can't be done. Don't let Dr. Schwartz take this out. And this was very early on before endoscopic surgery was really accepted. And of course the truth is five years later, it can be done. And I only say that to give people the confidence that these approaches are not experimental at this point, but they have good long-term outcomes as long as limited longterm, but reasonably long-term outcome. Same thing with size. You can take out very, very big tumors. This is a large pituitary adenoma that's invaded through the clivus and super seller. And obviously you I would take this out piecemeal. We can even go up into the lateral ventricles and remove giant macro adenomas that extend through an enlarged foramen of Monro. So let me show you an example of a craniopharyngioma. You can see this is in the Prepontine cistern and extends up a little bit into the third ventricle. The sellar is normal-sized and this is really going to be our corridor right here between the pituitary gland and the optic chiasm We're going to get right into the tumor, dissect our way around it and take it out. So let's go to the next movie. So in this example, you see the superior cavernous sinus. I like to open above and below the superior cavernous sinus or opening the dura now above of the tuberculum and plenum. And then we'll open the dura below and then we need to cauterize. This is a Pistol-grip cautery. Sometimes you can use a standard cautery, and it's not an ideal cautery, but it does work. And then we will cut out the superior cavernous sinus and the diaphragms sellar. Here's the pituitary gland, the optic chiasm, optic nerve. We open up the arachnoid to expose the A2 complex. There's the optic chiasm. We gently retract on the pituitary gland and now you'll see the tumor come into view. So that's the tumor right there. So we've been able to get into this tumor in a fairly central difficult to reach location by essentially just doing an extended transsphenoidal approach. We take our scissors, we can get a biopsy specimen, make sure we get a frozen section, and then you internally decompress it and dissect your way around it. The internal decompression in this situation we did with a Cavitron and It is possible to get small Cavitron in and I'll show you some other instruments that we like to use for this. There's some tumor attached to the back of the chiasm. And this is the view up into the floor of the third ventricle and hypothalamus And then the view of the stock. So we rotated the scope. Here's the stock going to pituitary gland, and here's the chiasm. So here's the post-op scan. And as we showed anatomically, we preserved the stock. Although this patient wasn't DEI postoperatively because probably a vascular disruption, but anatomically you can preserve it and Sometimes you will maintain function and here's the pituitary gland also preserved. What about larger craniopharyngiomas? This is a cyst craniopharyngioma. The sphenoid sinus is not as well as aerated. There there's some extending back behind the dorsum. So I'll show you an example of taking this one out. If we can go to the next movie, please. So in this situation, we are actually working with a one version of the 3D endoscope. You know, actually I think we skipped a movie. I don't know if that's true, but this is the movie from the subsequent craniopharyngioma. But what you'll see here is that the stock is here. We're working above the pituitary gland. We're dissecting around this large giant craniopharyngioma, dissecting the arachnoid. We then dissect into the tumor to try to internally decompress it. You can see that the stock, the tumor really comes off the stock. It's going to be very hard to keep this stock functioning and take this tumor out. We're internally decompressing the tumor but you can see the dorsum sellar on the other side and the pituitary gland stock more internal decompression. You can see the fluorescein around the outside. We're using something called the NICO Myriad to do a internal decompression. And this has a fairly large solid component. I'll show you the films afterwards Cause I think we skipped the actual video of the one, the cystic one. Now we're back using another endoscope using the HD stores endoscope and again, we're taking out more of the tumor working below the chiasm. It's within third ventricle and it's from calcified tumor. We just gently resect more and more. Make sure we work our way around it and dissect it free before we pull it out. We don't just pull blindly, but we dissect pieces free So after the surgery, we can look up into the third ventricle and see the choroid. Here we're actually going to resect the stock because I don't think the stock is going to work. And so we want to make sure that we cure this patient. If we're going to cure them, sometimes there's residual tumor in the stock. And then we look up into the third ventricle and see the choroid plexus. Here we are back using the 3D scope. And this is one eye have the 3D scope just to show you the different scopes, give you different kinds of fields of view. And here's our closure, We take fascia Lata, That's larger than the opening and we countersink a piece of MedPore. This is our gasket seal closure. Go back, please. Actually, I'll go to the slide show. Here's the post-op scan on the cystic craniopharyngioma, where we preserve the stock and this patient actually had a functioning pituitary afterwards. Here's the stock. This is the example of the craniopharyngioma that we just saw in the movie. And it's a fairly large craniopharyngioma. You can see a normal sized sellar and we took that whole tumor out just through this little passageway between the chiasm and the pituitary gland. It's just shows you the T2. And here's the post-op scan showing a preserved stock in a situation. In some circumstances, we just want to do a biopsy. So this was a woman of childbearing age and she had what we thought was a craniopharyngioma. We wanted to make the diagnosis, but as you can see, the tumor is within the stock itself. So in this situation, we could just do a small biopsy, preserve the stock, try to keep her pituitary functioning as long as possible, take a biopsy and send her for a fractionated radiation. This is a giant craniopharyngioma, and this represents a more difficult problem because you can't do this just through a suprasellar approach because there's also tumor in the clivus, behind the clivus, the prepontine cistern prepontine sister, excuse me. So this would require a more extended approach with either a pituitary transposition or an above and below approach, or even just resecting the pituitary gland in order to get a big enough opening But you can take out these larger giant sized tumors and here's a nasal septal flap, and I'll show you how we, how we do that. Postoperatively, you see beautiful views of here's some stock basal artery, third nerve on either side mammillary bodies, posterior cerebral superior cerebellar arteries. And then looking up into the third ventricle in that last patient, you can see that she had some tumor that was just grossly stuck to the lateral walls of the third ventricle hypothalamus. And we elected to leave some tumor behind in her because we did not want to damage her hypothalamus. She had some hydrocephalus and here's another beautiful view of foramen of Monroe from below and the fornix on the tela choroidea and the choroid plexus. So what about meningiomas? Some people think that these meningiomas shouldn't be taken out through the nose that they're easy to do from above, but I'm going to show you some examples of meningiomas that I think are appropriate to take out from below through an endonasal endoscopic approach and talk about what some of the advantages of that may be. So let's go to the video please. So what you see here is a sellar and a planum. We've removed the bone of the planum and the sellar, and we get right to the tumor. So here's the pituitary gland below. This is plan and bone removed and we're internally decompressing this tumor and this situation, we started with a Cavitron, weren't so successful. So we went over to a device called the Elliquence. This is a nice device because you can bend the tip. It's a radiofrequency lesion and it will decompress and vaporize some tumor and also get your hemostasis. So it doesn't bleed. So we like to use this for meningiomas and we do a lot of internal decompression and then extra capsular dissection, internal decompression, extra capsular dissection, keep going back and forth. You can see the arachnoid attached to the back, often there's a nice arachnoid plane around the backside of the tumor. And there's the superior hypophyseal artery. You are doing more internal decompression of the tumor. You can see the optic nerves coming into view. We start working away around the other side of the tumor, do more internal decompression. Here's the optic chiasm and the optic stock, some more internal decompression. Here's the other superior hypophyseal artery and we carefully dissected off there. You can nicely see the diaphragms sellar here. And these tumors often involve the diaphragms. If you want to get a complete resection, you also have to resect the diaphragms sellar. So we can use microdissection through the nose, just like we can use it from above and remove all of the tumor and the diaphragma and get the tumor out. Now, in this situation, we didn't open up the optical canals medially, but we inspected them and I'll show you a 45 degree endoscope. Here's the carotid artery, optic nerve. We're going to look up into the optic canal to see the hypothalamic artery, which is inferior. And we'll show you that we did not see any residual tumor. So we didn't open up the optic canal in this particular case. Here's the optic nerve. Here's the basal, the frontal lobe, the A2 Branches. And then we're going to look into the other medial optic canal and there's the stock. So we got a nice resection and here's our closure again, this is fascia Lata. That's counter sunk with a piece of MedPore that buttresses it. And then we cover that with a nasal septal flap. Now we don't put a balloon in the nose although Some people have done this in the past to keep that nasal septal flap in place. We'd like to put DuraSeal and we use a 14-gauge Angie cap and a little rain curate to direct the flow. Here's the engine cap in the rink here at, and we try to cover the whole thing and the Duraseal will harden and keep that flap in place for the first couple of days, until it gets its own blood supply to the bone and starts to heal there. Here's the post-op scan showing you that nasal septal flap and the tumor has been removed. Now, what about a case like this? This is a little bit more complicated because it looks like there may be some tumor around the carotid arteries. It looks like the tumor may be involving the A2 branches and encasing them, maybe in the medial optic canals. It certainly is in the medial optic canals. Here those A2 branches farther forward, tumor extending a little bit lateral, tumor and the medial optic canals. And here's that sagittal view. This actually shows that there may actually be a plane around those A2s and the tumor may not be encasing them. But this gives you an idea also of how far forward you have to go to get that dura tail in the planum. So I'm going to show you how, how we took this one out. Let's go to the next movie. This situation we knew there was tumor in the medial optic canals. So of course that has to be opened up. So here we are opening up the dural. We've made our planum tuberculum opening. This is the sellar below. And the advantage of course is you get right into the tumor. So the first thing we do after opening the bone and opening the dura, we start internally decompressing it like it were a convexity tumor. There's that Elliquence device. Here's the diaphragms sellar. Here's the pituitary gland. We're dissecting the tumor off the pituitary gland, taking the diaphragms sellar And now we're opening up the medial optic canal with a kerrison in order to take tumor out of the optic canal. And you can see you just continue your opening laterally and you'll get there. This is the sheath, the optic sheath. We use a doppler and make sure the hypothamic artery is down here, open up that optic canal and take out whatever tumors in the medial optic canal. So after we're done, this is the lamina terminalis, optic chiasm A1, ACOM, A2, This is the stock below. You can see the medial optic canal has been opened on one side and they're all the way to the other side. So you have the optic nerve really open from medial orbital apex to medial orbital apex. Looking up again, You can see the A2 branches, gyrus rectus, and here's that optic nerve well exposed. So here's post-op scan, coronal, another view, and the sagittal here's the pituitary gland. You can see the tumor has been removed. Here's another example of a planum meningioma. This one was in a more elderly woman. And it turns out that if we can go to the next movie, the artery of a Heubner was actually encased in this tumor. And we did not think that we could dissect it off. There really wasn't a good plane of dissection. So we had to leave some tumor behind. And I just want to show you an example, cause this shows a microsurgery that can be done through the nose, using an endonasal endoscopic approach, and that we're not pulling this tumor off a blood vessel, which would tear the blood vessel, but we're carefully cutting the tumor, doing sharp dissection. And if the tumor doesn't come off, then we will obviously leave a small bit of tumor behind and we can follow it on If it grows, we can use radiation. So it is possible to do microsurgery through the nose. It's more awkward for sure than doing it through a large craniotomy, but with practice, it's not that difficult. The other thing I wanted to show is that the optic nerves and a lot of these meningiomas is very, very thin. You can see this thinned out optic nerve That's compressed by the tumor against the A1 branches. And what's nice about coming in from below is that you don't have to manipulate the optic nerve at all. If you're coming in from above and you have to retract this optic nerve a bit, it's already paper thin and the chances of damaging it in my opinion are higher. So here's the post-op scan is a little bit of fat in there. There's a gasket seal. And then here's our nasal septal flap. This is another meningioma We took out planum meningioma, and this is the post-op scan with some fat in the cavity. These are pre-op and post-op visual fields. And there was made about her and she obviously gave permission for this to be done, but she was so happy to have her tumor out through the nose that stores and she agreed to make a little ad about it. So what about Post-Craniotomy Residual? Sometimes we see tumor that's left behind from planum meningiomas that would not take it out through a craniotomy. And in this situation, this is the optic nerve. This is the carotid artery. You can imagine coming in from above, there's going to be a blind spot and sure enough, this is where your blind spot would potentially be from above. You don't just have blind spots from below. And that's where the tumor was left behind. And you can see through these images that the tumor presents itself right to this sphenoid sinus. So although it was left behind and then started to grow from a craniotomy, it's actually a nice case to do through an endonasal approach. Here's another meningioma, decent size. It extends down into the sellar, It pushes the pituitary gland below down. Excuse me, let's I think there's a video here. So here's the extended approach. This is the sellar Here's the planum, we're taking off the planum with a kerrison. There's a little piece of Gelfoam here to stop bleeding. We do get bleeding through the nose also, this is a backbiting kerrison that we use to take off the planum because the planum comes out towards you and sometimes getting a regular kerrison can be difficult. we're internal decompressing with this Elliquence device, doing more internal decompression. We're working above the pituitary gland. You can see, we start to get some fluorescein. This movie is running in slow motion for some reason. Now we're dissecting around the outside of the tumor. There's a nice arachnoid plane and we're going to use microdissection just like we would use through a craniotomy. You can start to see the A2 branches, the ACOM. This is the optic nerve. The tumor was very stuck to the optic nerve. Here We're internally decompressing with a sonda PEG, and now we're doing a microdissection to try to get the tumor that's stuck to the optic nerve off the optic nerve. And we try to resect the tumor, Sorry. We try to retract on the tumor and not on the optic nerve. Here's the optic nerve below. And here's the tumor that we're sharply dissecting off and sharply dissecting it off the A2 branches as well. Now, as I mentioned before, we'll often go back and do more internal decompression because we want to be safe. Here We are taking the tumor off the stock. The stock will come into view in a minute. Here's the stock, very thinned out by the tumor. We can sharply dissect the meningioma off the stock using the arachnoid plane, opening up the medial optic canal, Making sure we're around the tumor laterally. Here's the optic nerve. And we're going to dissect the tumor in this situation, bluntly, and then sharply off the A1 branches and the optic nerve. You see how Stuck the tumor is to the bottom of the chiasm. Here's a nice example of taking the-

- Yeah. May I ask you what should you do in this situation if you run into bleeding?

- Well, it depends on the kind of bleeding. Let me just show one quick thing. Look at how thin that nerve is by that A1 branch. And then here's the closure just while the movie's going. I just want to narrate it and then I'll come back and talk about bleeding. We often put fat in, but we don't pack the fed in here's that gasket seal. You can see the fascia Lata that's larger than the opening. And then we countersink a piece of bone. So if you encounter bleeding, it depends on the kind of bleeding. If it's arterial bleeding, you have to cauterize it. You know, you have to, you can't pack off arterial bleeding in the brain. So you'd have to put a bipolar in there and cauterize it. And if it's just venous bleeding, you could try flow seal. You can try a Gelfoam and gentle pressure, but obviously you have to be very, very careful not to cause any bleeding, but you can bipolar small arteries, you know, using through endonasal, just like you would through a craniotomy.

- Let me ask you Ted. How do you manage... Have you ever turned your endoscopic approach to transcranial because you felt the bleeding was not controllable through the endoscopic approach?

- We've never done that. We've never had to do it. The only times that we've had so much bleeding, either a once a carotid injury and once in a hypolothamic injury, it was in sphenoid sinus So there was no cranial opening. And so we packed it off and went to interventional neuroradiology and took care of it that way. And actually both of those patients did very well. If the brain were exposed, you'd have to cauterize it. So here's the post-op scan on that case. And you can see the MedPore buttressing it, and the fat around the outside. And then the nasal septal flap below. This is that image I guess our slides were out of order a bit of it. You can see some of the tumor in the medial optic canal. This was the residual after the craniotomy. And then here's the optic canal that we opened up to take out the rest of the tumor. Sorry about that. Here's the post-op scan of that medial optic canal tumor and the nasal septal flap. So what about giant pituitary macroadenoma ? So these extended approaches can be very useful for giant tumors. So what I like to do now is actually do a transtuberculum approach, figure out how much of the tuberculum I need to take out in order to do an extra capsular dissection to make sure I get the suprasellar component of the tumor. Sometimes they will descend when you take out the bottom of that tumor but sometimes they won't. The diaphragms can be intact and keep that tumor up there. So in that situation, we would... This would be a standard opening for this giant adeonoma, but we could extend that and actually take off the tuberculum and the planum in order to see the dural of the planum behind there to take out the giant tumors. And then these giant tumors we would take, we would close with a nasal septal flap as well. Here's a post-op scan. What about residual after a microscopic transsphenoidal surgery? Sometimes we see patients where they've had a transsphenoidal surgery and the surgeon used a microscope and a Hardy retractor, and unfortunately could not get out the supersellar tumor because it did not come down. So we can go to the next movie, I'll show an example of one of those cases. So in this situation, you can see the prior bone opening that the prior surgeon used. And we are extending that superiorly in order to do a transplanum transtuberclum approach, to get the supersellar tumor. So often what this requires is just extending the prior opening. There's the bone that was placed by the prior surgeon as a closure. And we'll keep opening more superiorly in order to go right directly into that superior tumor. The dura often can be in your way since we're not going to do a primary closure, we'll resect it, you can do with a kerrison. You can cauterize it back, but it's important to get those dura flaps out of your way. Now you can see the optic chiasm and here's the residual tumor extending up from the sellar and it'll go behind the Chiasm and it's pretty stuck. So we sharply and bluntly dissected off the chiasm, take our time internally decompress, make sure that the superior hypocrisy arteries and perforators are all not damaged or torn. And when we're done, of course, we'll have that nice view up into the third ventricle to make sure we've gotten out all of that suprasellar tumor. Here's the chiasm still a little bit more tumor, but here's that view. choroid plexus third ventricle, most of the tumor has been removed. And here's the postop scan. On the last case, I'm going to show suprasellar approaches this epidermoid this case You can see the sellar and how the tumor extends down into the sellar. It also extends up in front of the back of the planum. And so in order to get to this part of the tumor, of course, you would need to take out the tuberculum and some of the planum Cause if you come in at this angle, you're going to transect the tumor and this part is not going to come down. So can we go to the next movie? So in this approach, we opened up a little bit more of the sellar. This is the superior cavernous sinus that we're cutting, opening up the dura to expose this epidermoid. This is the planum up here. The leaves of the dura we're cauterizing back so that they're not in our way because they will obstruct our view. showing you how the bipolar can be used endonasal. And then course we get right into the middle of the tumor and epidermoids are usually soft and suckable, so we'll start by internally decompressing it, and then you'll see the fluorescein stained CSF around the outside. Now, if we just use the zero degree scope, we would only take out a limited amount of the tumor. You can see the optic nerve coming into view. So then we'll start to advance our scope and look around the corners a little bit. And here's the A1 branch on one side. Now we're working within the cavity, moving the scope into the cavity and using an angled endoscope. Let's see the carotid over here. Again, We think we may have taken out everything, but we'll go in with another angled scope. Try to look around the corner and sure enough, if you look hard enough, there's a little bit of residual tumor and we'll take an angled suction and instruments to get that out. You can see the stock pushed off to the side. Here's the sellar, here's the carotid all preserved. We got that last bit of tumor out. Go back to the slide show. Here's our post-op scan showing you this was the area of opening. And this is about a centimeter opening in a skull used to take out that whole epidermoid and you can see the floor of the third ventricle. So what about the cavernous sinus? As I mentioned before, the medial cavernous sinus is easily accessed through the endonasal endoscopic approach and the advantages the optic, sorry, the nerves that move the eyes, the third nerve, the fourth nerve, the sixth nerve are all lateral to the carotid. And so many of them are in the lateral wall of the cavernous sinus, and you can approach medially without a risk of injuring those and the carotid artery itself is often pushed laterally. And when we do this approach, we take off all the bone over the cavernous sinus, and you can keep removing bone laterally over the cavernous sinus. It's covered by dura and then use a doppler and find out exactly where your carotid is. And then you can make sure you open up the dural, excuse me, all the way to the medial wall, the cavernous sinus, and then work behind it with an angled endoscope. And by taking off the bone, it allows you to retract that dural and retract the carotid a little bit in order to see behind it. So this is just an example of another cavernous sinus, medial cavernous sinus tumor That's pushed everything laterally, showing you the pre-op scan and the postop scan with a stock on a pituitary gland. And this situation it's actually possible to go through the ethmoids lateral to the middle turbinate, to get to the lateral aspect of these sphenoid sinus. And that gets you a better lateral view. So this is actually a cavernous angioma within the cavernous sinus and the pituitary glands over here. And you can see the cavernous sinus is filled with this sort of red beefy tumor. We were hoping we could go in and just sort of suck it out, but that was not going to be the case. So the bone over the cavernous sinus has been removed here. So we use our doppler and we say, "All right, so where's the carotid artery here? How far can we open the dura safely?" And it turns out the carotid artery was pretty far away. So we were able to open up more of the dural than we would have thought we would be able to do. And we can figure out how far we can do that safely, and then try to dissect our way around this cavernous meningeoma mobilize it now. Yeah, you will get blood. And you saw a little rush of blood from the cavernous sinus when you do that. But if you pack that off with some Gelfoam or some Surgicel or TISSEEL, you can keep working your tumor and get it out from the cavernous sinus without too much bleeding. Here we're just taking the last little attachment of this tumor as we work the top part. Let me get the whole thing out. This is a chordoma that extended into the cavernous sinus, just showing you that a film pre and post-op, here's a chondrosarcoma and again, this is a tumor that's extended pretty far into the cavernous sinus but as you can see, it's pushed the carotid artery laterally. So there's a nice corridor here, right into the tumor through an endonasal approach. So here we're opening up the dura over the sellar. The pituitary Gland is actually over here. This is the cavernous sinus. We've exposed the cavernous sinus by taking off all the bone, we've dopplered the carotid artery to find that it's all the way over here. So we actually can open up pretty far laterally to get into this tumor. You can see this chondrosarcomas are soft suckable tumor. So we do our internal decompression and take the tumor off the pituitary and dissect all the tumor off. You can see there's a CSF leak and using the fluorescein, you can see exactly where that CSF leak is, which is really nice Cause when you put your fat graft in, you want to make sure you get it right over that area of CSF leak. Here we are working more laterally into the cavernous sinus with an angled endoscope, an angled suctions an angled in order to get the tumor off the carotid artery and out of the cavernous sinus. Here all you'll see the carotid artery and there's some bleeding from the cavernous sinus, but we can work on either side of it. You were working in front of the carotid artery, and then when we're done, we fill it with low seal for hemostasis. And here's the post-op scan. So you can see we've completely resected that tumor around the carotid artery Here is the normal pituitary gland. So what about the transsphenoidal, transclival approach? So part of the clivus of course is just this behind the sphenoid sinus. So there's a whole aspect of the clivus that we can access through this sphenoid sinus. So here's an extra durachordoma. Here's an intradurachordoma, and you can see that the inferior extent of it doesn't really go that much below the sphenoid sinus. So we can use the Sphenoid sinus as our main corridor to get in here. Here's an androgynous cyst, prepontine interpreterocular cistern and a little bit behind the pituitary gland But again, you could see if we come in anteriorly, there's just a little bit of bone we have to drill off and we're going to fall right into that cyst. So let's talk a little bit more about the transclival approach, unless we want to make that part two. Aaron What do you think?

- I think we can go ahead and stop here and ask our viewers to refer to the second part for the additional approach you just talked about. So I want to thank you again and we'll proceed to the second part.

- Thanks Very much, Aaron.

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