Cavernous Sinus Meningiomas: Variants of Strategies and Techniques

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- Colleagues and friends, thank you for joining us for another session of the virtual operating room. Our guest today is Dr. Jacques Marcos. He's a professor of neurosurgery and auto laryngology at university of Miami, as well as the co-chairman there. He's also doubling as a vice-president. He has many numerous international involvements with leadership in neuro surgery, and most importantly, he's very much internationally renowned for his excellent technical skills in skull based surgery. Jacques, I really wanna thank you for joining us today. I know you'll be talking about anatomy, surgical techniques, philosophy, different approaches for resectional complex, cavernous sinus lesions, as well as meningiomas. I'm very much looking forward to learning from you. Please go ahead and thanks again.

- Thanks Aaron, for including me again. I think for the second time in your extremely successful series. Thank you for educating the masses every Monday, and again, pleasure to be with you. What I thought I'll talk about today, I'm titling it Cavernous Sinus Meningioma Variants of Strategies and Techniques. And I would like to acknowledge my superb fellow in cerebrovascular and skull base, Nick Khan, who has been with me this year for helping me throughout the year with multiple projects, including helping me put this presentation together. So I'm gonna miss him when he's gone next week and he will do fantastic at the University of Tennessee in Memphis, where he did his residency. So let's get going. We are, of course, I'm here in Miami broadcasting to you. I encourage you to come and visit us at the University of Miami Jackson Memorial hospital. We have two main hospitals. UMH on the bottom right, and the Jackson Memorial hospital on the bottom left. Very busy places. So my disclosures are completely irrelevant to this talk. So here is the outline. I'm gonna remind some of you, I assume of the history of the cavernous sinus very briefly. Then of course, I'm gonna focus on cavernous sinus meningioma. And when I say cavernous sinus meningiomas they are not all pure cavernous sinus. If they're gonna be in the cavernous sinus, into the orbit, into the petroclinoid region and so forth, and try to give you at least my, I don't want to call it philosophy it tends to be arrogant, when somebody says, I'm gonna tell you my philosophy about something, just gonna give you my own biases and the lessons that I have learned over my 26 years of being a neurosurgeon with case examples and videos. And then I'll conclude with my summary. So here is a brief history of the cavernous sinus. This is the cavernous sinus. Of course you recognize a dissection. Actually, this dissection is by Ernesto Cascarilla who worked with me more than 20 years ago. Very talented neuro anatomist, neurosurgeon, and did many of the dissections that we have published about. And that's one of his. Galen described the retia, a parasellar carotid retia bathed in venous blood. He did that in the second century. Raymond de Vieussens described it as the receptacle, which received the cranial nerves along the so-called Turkish saddle, in the 17th century. The term Sinus Cavernosi was created by Winslow, the same Winslow of foramen, of Winslow fame. Those of you who remember your abdominal peritoneal anatomy, the lesser SAC and greater SAC connection. That's the same guy, in the 18th century. And his description actually is still quite modern. If you read, reservatories of a very particular kind containing not only blood, but considerable vessels and nerves, and likewise, a spongy or cavernous substance full of blood, much like that, of the spleen or corpus cavernosum. Of course, since then, there's been lots of controversy, which we're not gonna get into, about the exact anatomy of the venous channels, because it does have a bearing on how you operate on the cavernous sinus. Are they trabeculated? Is it an open sinus? Is it irregular network or plexus as Taptas, bonnet and Parkinson thought? Or is it more like Rhoton, Krivosic and Hakuba thought, a combination of trabeculated and open venous channels. The first attempts you can imagine, the first attempt at surgery of the cavernous sinus must have been horrifically difficult. Krogius 130 years ago, amazingly resected a neurinoma of the cavernous sinus. Browder in 1937 packed a carotid cavernous fistula with muscle directly. Then Dwight Parkinson from Manitoba in Canada, really studied the cavernous sinus. He named it, the Anatomical Jewel Box. His concept of the CC fistula modified over the years was work from his original papers. And to this day, I still think, some of the best venous corrosion anatomical studies are his. They're not in color, but you can see the level of detail. This is how we have the term Parkinson triangle between the first nerve and V1. That was the natural window for him to use, to enter and pack a carotid or direct or light gate amazingly a carotid cavernous fistula in the cavernous sinus. Then of course, Dolenc followed. And I guess most of us would call this era, the modern era of cavernous sinus surgery in the early 80s. But not to forget, absolutely never to forget the amazing contributions of Akira Hakuba in Japan. Without going into too much detail, you're encouraged to read that history by reading the papers of Hakuba and Dolenc, that were pretty much synchronous. Hakuba really described that peeling, that we talked about in the lateral wall, the intradural peeling. Dolenc talked about the direct microsurgical repair of vascular lesions, 83. In 85, Dolenc published his Combined epi- and subdural direct approach to carotid-ophthalmic artery aneurysms. Then I would say began the conquest of this no man or no woman's land. And this is El Capitan, the peak of El Capitan. It was a tough road to climb and we're still climbing it. Everybody was interested in that field. So quick depiction, this is Hakuba's appealing. This is from a Mayfield Clinic publications. This is the Kawase peeling in the floor of the middle fossa. And this is Dolenc's peeling in the roof of the cavernous sinus. And as long as you know how to manipulate the third nerve, that's what Dolenc's technique clinoidectomy and so forth is all about. And again, remind you of a couple of important people's. To do that you of course need to understand the anatomy. It does start with the anatomy of the orbit without taking you into too much detail today. But I remind you that the orbit is made out of seven bones. Here they are colored one after another. And the important thing for our purposes today, of course, is the orbital apex. You can see here, the optic strut, the anterior clinoid, or you can see how the optic canal is separated, from the superior orbital fissure, by the optic strut. Now from the transcranial point of view, again, these are Rhoton's pictures. We're talking about understanding where the optic nerve and canal are, where the superior orbital fissure is, how the carotid artery make it slope behind and under the clinoid and therefore where the optic strut will be once you drill the clinoid. Here is a lateral view on the right side. Again, superior orbital fissure, optic nerve, optic strut after drilling the clinoid, the approximate course of the carotid artery. A good view of the optic strut with a skull held at an angle. So you can understand how it attaches the anterior clinoid to the body of this sphenoid. It is important to understand the oculomotor triangle, one of the 10 triangles of the cavernous sinus, which will summarize in a slide a little later. But of course it's a triangle, therefore it has three sides. There is a interior petro-clinoid ligament, there is the intraclinoid ligament, and that is the posterior petroclinoid ligament. And the third note of is at the center. Looking at the cavernous sinus dissected, completely dissected, from laterally on the right side. Let me do that. This is of course the third nerve here. This is the fourth nerve crossing over the third of nerve in the superior orbital fissure. Here is V1, and this is V2 and we don't have V3 in this view, but it's at the bottom. This is distal and proximal dural ring. Between them, meaning right here, would be the clinoidal segment of the carotid artery, which is neither a subarachnoid nor intracavernous. It's in between. And of course, in front of it is optic strut. So it's very important to recognize that the optic strut is in exact interior limit or anatomical relationship of the clinoidal segment of the carotid artery. Let me clear those. Another intracranial view of the cavernous sinus. Many years ago, when I was really, well as I was teaching residents and I still do, the residents would get a little confused with the anatomy of the frontotemporal dural fold, and how does the Dolenc technique work? And it occurred to me that if I simply reverse the steps of the Dolenc technique they would understand what they are looking at better. And this is what I mean, and this is actually how I do most of my cavernous sinus surgeries, the way we described it in 2003. So very simple modification of Dolenc. So Dolenc said, when you get to this area here, the frontotemporal dural fold, you can take a curved scissors and cut it backwards. The problem with at least trainees that they haven't done too many of these cases, they're nervous because they assume they might cut the contents of the superior orbital fissure. So what I suggested is let's flip the steps of Dolenc. Let's peel in the dural off the lateral wall, so that you can see the tip of the anterior clinoid, from the middle fossa. So I know it sounds counter intuitive that you're seeing the tip of the clinoid from the middle fossa rather than the anterior fossa, but that's how it is. And by doing so, then what you're left with is a frontotemporal dural fold hanging in the breeze. And you know exactly that this is how you need to cut it parallel to the anterior clinoid. Now, those of you who've done this surgery before, might feel that this is redundant and unnecessary, but I know from talking to trainees that they actually appreciate that depth view. So they feel more comfortable cutting the frontotemporal dural fold. So this is again, one of our cadaveric dissections at the time. I'll take you through those steps I just described. You see the clinoid, then you have the frontotemporal dural fold, completely free anteriorly and posteriorly. You know where the superior orbital fissure is. You can imagine through the bone, through your to quote good old Dr. Rhoton through your x-ray vision, you can recognize the nerves on the other side of the periorbital. And here is another dissection from Ernesto Cascarilla. And do you know how to cut the frontotemporal dural fold? Then you cut it. And then you have a full view as seen in the surgical view of the anterior clinoid, which you will drill next. And once you've drilled it as seen in this cadaver, again, you can see the optics throughout the clinoidal segment of the carotid artery, the distal dural ring, and the proximal dural ring. Here, of course, third nerve, fourth nerve coming over here, crossing over the third nerve right here. Again, a surgical view on the right side of an example, I'm gonna run through those steps. I've already, I think, mentioned them at least twice. Lessor wing you can see, LW, greater wing, GW, frontotemporal dural fold, peeling greater wing. Peeling, this is what Dolenc would do now, which is cutting it. Now, you certainly can do it if you know what you are doing and your experienced, no problem doing that. But if you wanted to know exactly where you're heading, do this step first. Peel the lateral wall. You can then see AC, the anterior clinoid tip from the middle fossa. You know where SOF, superior orbital fissure is, this is anterior clinoid, then you can cut your frontotemporal dural fold, in full view and confidence. And that is the anterior clinoid, which you can go ahead and drill or whatever the case may be. This is now a schematic of the Kawase area. I'm not gonna draw on it because it's self-explanatory. The GSPN, the horizontal petros-carotid, the V3 and the true petrous apex under V3 and the basal turn of the cochlea and the internal auditory canal. And of course, the RQ at the eminence at the back, generally makes an angle of 120 degree, meaning, with a GSB, and meaning this angle is about 120 degree and the bisector is usually the IAC. That's one of the many ways to understand what IAC is. This is one slide summary of my concept of how to approach lesions of the cavernous sinus. If the lesion is localized to the cavernous sinus, then the approach should be extradural, intradural, frontotemporal or possibly subtemporal. That's in general. If the lesion is both intra and extra cavernous sinus, you can see all the approaches that are available. Usually the extra cavernous sinus component, I use as my avenue to the cavernous sinus. So if it's in the paranasal sinuses, you're gonna do a cranial facial or the orbit you're gonna do cranial orbital and so forth. And of course, endoscopy, endonasal endoscopy is key to many of those paranasal sinuses or cellar lesions that extend into the cavernous sinus. Harry Van Loveren about 20 years ago or so, systematized the Dolenc approach. And this is very good for teaching purposes. Six extra dural and six intradural stages. So I'm gonna summarize for you what these are. We'll go quickly, so we can get perhaps to the examples. So we all do them. I mean, those of us who do this routinely, I mean, don't think of them as individual steps, but when we're teaching trainees, it's nice to give it a step number. So they know, do this step, then do this step. So this is step one. You're dealing usually with the orbital roof until you see the periorbiter. Step two or 1B, unroof the optic canal, then do the extra dural. And I do do extra dural anterior clanoidoctomy on all my tumors. There is almost never any need to do it intradural. It's much better to do it extradural for four tumors, Steps three is unlocking the superior orbital fissure. I cannot see the top of my slide, but that's okay. The orbital roof, you can see the anterior clinoid, SOF Step four, foramen rotundum. Five is foramen ovale. Step six is exposure of Glasscock's triangle, which of course is lateral to GSPN while Kawase's area is medial to GSPN. And of course, this is transected middle meningeal artery. This is another depiction of the distal dural ring, but then you, of course, have to imagine the carotid artery coursing, vertical petrous, horizontal petrous, ascending cavernous, then horizontal cavernous, and the last serum segment in between. And that is a horizontal cavernous. And then the proximal dural ring, then the distal dural ring and between them, the clinoidal segment of the carotid artery before it becomes ophtelmic segment and communicating segment. And here's an endonasal endoscopic, beautiful Rhoton dissection showing the whole course of the carotid artery. And you know that there are many confusing classifications of the carotid artery. And probably this one makes the most sense from C1 to C7, from proximily to distally, you can follow it, whatever classification you want. What's important are not the names, are not the numbers, but what's important to know is where does each segment begin? What's next to it? And where does it end? What are the anatomic relationships? So that when you're operating, you know how to avoid injuring the artery. And whatever system works for you is what you should use. The intradural steps are here. The six intradural step of the cavernous sinus. It's very important to understand where the fourth nerve enters the free edge of the tentorium. The fourth nerve, like the third nerve. has a sleeve of tentorium around it, and you can cut it, free it up, exactly like you can the third nerve. So now at step five, you dissect the V1. At step six, you dissect or expose cranial nerve six. And that is the hardest nerve to find and to preserve in cavernous sinus surgery. Because of course, it's the deepest, because it is anchored at Dorello's canal right here. And Felix Umansky many years ago has a beautiful anatomical paper dividing Dorello's canal into three portions. You could read that to understand in more detail. But that will be your last step. Now it doesn't mean every cavernous sinus surgery, you need to do all 12 steps, you tailor it to what the lesion needs. But if you've done all that, you can access the 10 so-called triangles of the cavernous sinus. And I'm gonna put them all here, and I'm going, don't worry. Those of you who don't remember their names, I'm going to overlap their names. And here they are, Clinodal, Oculomotor, Suprtrochlear infratrochlear, anteromedial, anterolateral medial, of course, is a Parkinson's anterolateral, Glasscock, Kawase and the two triangles around the six nerve inferomedial and inferolateral. And of course, each one of them has their uses. And another nice Rhoton dissection. So let's come to the clinical matter at hand today. Now that I hope I familiarized you again with cavernous sinus anatomy. We can talk for hours about it, but there is no substitute to going to the cadaveric lab and doing those dissections yourself. As I did when I was a fellow, that's the only time I really understood the anatomy. Reading books and listening to lectures, gets you only partially there. Cavernous Sinus Meningioma, when should we operate? Well, they've got to be symptomatic generally, and or radiologic progression, or you're suspicious that it may not be a meningioma. Symptomatic holocavernous meningiomas with normal extraocular movements, I will not operate unless I am not sure is a meningioma and I need the biopsy, I will do radiosurgery for those patients. We are not gonna talk about that today, but this is an old paper that shows it is hard to beat tracheal surgery for those, and I'm being very specific, holocavernous within the cavernous sinus, not extending beyond it, normal eye movements nor compression of the cranial nerves. It's very hard to beat, if they're symptomatic, I will treat them with gamma knife. If not, I will just observe them, but I will not operate on those patients. And it's paper after paper have shown the wisdom of that. Once you're operating on the carvenous sinus, the texture of the tumor of the meningioma will determine the extent of resection. It doesn't make sense to go into the surgery saying, I am going to remove this portion only. You don't know. You may be pleasantly or unpleasantly surprised by the texture of the tumor. And that will determine the radicality of your resection. For example, this is an older case, but I will never really forget this case. This is completely invading the cavernous sinus. It's a meningioma. I promise you if I showed this case today to 10 or 20 of my skull-based colleagues, and I told them the patient has normal extraocular motion, I am very sure many of them will say either partial resection or maybe observation, or maybe gamma knife. Very few will say, go in with the intent to remove it completely. So I went in not knowing what I will achieve and what I achieved is uncharacteristically for these cases, a Gross-Total Resection. Why? Because this tumor happened to be quite soft. And it was very easy without doing much boney exposure to have this view that we have here. You can see the basilar, you can see the pons, you can see the supraclinoid carotid. The tumor was very well behaved, and I managed to remove it completely with the so-called half and half three temporal trans-sylvian approach. And this is a post-op MRI. Excellent, gross-total resection had only a very temporary third nerve palsy that disappeared within three weeks. So I'm showing this case because really this is the exception more than the rule. But it does show you that you need to be open-minded when you operate on these cases. The second, another point, the way I devise this talk is kind of talk the lessons that I've learned, what I consider some of the most important lessons I've learned through my mistakes or my watching others and show examples about the lessons. Meckel's cave is not cavernous sinus. Perhaps many referring physicians or neurosurgeons who don't do skull base surgery as has happened in this case have called this case that was referred to me, as invading the cavernous sinus. It's not invading the cavernous sinus. The cavernous sinus is completely clear of tumor. The tumor is in Meckel's cave, and therefore this case is completely operable. As of course, it should. It's large, causing dizziness, headaches, and patient has normal hearing. The second mistake is to call this a Petro-clival meningioma. This is an abuse of the nomenclatura. This is not the Petro-clival meningioma. This is a Petrous, an anterior petreus meningioma extending to Meckel's cave. This is a much easier case than a true Petro-clivo meningioma, because it is lateral to the trigeminal nerve, and it's not medial to the trigeminal nerve. And that is a definition of what should be the differentiator between anterior Petrous and Petro-clivo. So the way I would approach an anterior petrous meningioma that is entering Meckel's cave, that is predominantly in the posterior fossa, but a little bit in Meckel's cave or the middle fossa is a simple way, well it's not simple, but the retrosigmoid approach with a suprameatal drilling. And that is what was done, what I did on this case. You can see the drilling the supramaetal bone that Majeed Sammy popularized 30 years ago. That gives you X from the intradural retrosigmoid angle, gives you excellent access to Meckel's cave. And you can see the meningioma piece in Meckel's cave. I'm almost pulling it in one piece. Almost because you still have to chase the tiny pieces that you're leaving behind. But that's an excellent expeditious approach. And here she is post-op. You can see the gross-total resection and she can hear. And the only reason my incision is so long, is I like to take autologous pericranium from the patient to duraplasty if necessary. And that's what I did here. In contradistinction to this case, this case is a true Petro-clival meningioma with partial entry into the cavernous sinus. Why is that? Because the epicenter of this tumor unlike the previous one is at the Petro-cliven junction. Much more medial than the previous case I showed you. And many neurosurgeons would approach this tumor in different ways. I have not changed the way I do it for these cases. I still use the Petrosal approach, which is the post, to be very clear, this is the posterior petrosal not the anterior petrosal. This is not Kawase. This is posterior petrosal. Sam Almafty of course popularized it many years ago. And there are varieties of different petrosal. There's the presigmoid retrolab, presigmoid partial translab, pre sigmoid complete translab or complete transotic or complete transcochlear. We're not gonna go into all those details today, but almost always, we're gonna utilize a retrolab pre sigmoid combined subtemporal to of course, save hearing. So that's what I did with this case. I always worked with my neurotology colleagues. They initiate the retro lab drilling. Then as you can see, there is always a nice space. Well, not always most of the time, between the sigmoid and the back of the otic capsule on average, it is one centimeter of dura, where the endo lymphatic sack lives. And that's where you're gonna make your dural opening along with the temporal dura opening. So after doing the temporal craniotomy, we will make an incision that comes like this. Another incision that comes like this. You stop in between because what's in between, of course, is the superior petrosal sinus that I normally clip with two wet clips and I then enter and cut the tentorium. So that's a, and by the way, once I'm in, you can have a nice view. In this case, of the fourth nerve, you can see it completely draped on the tumor. And I skipped that video for the sake of time. I'll have other videos to show you, but that's a gross-total resection of this tumor. In spite of that fourth nerve really affixed to the tumor, I did enter the cavernous sinus, as you can see. And how does the patient look post-op? Here is again, postoperative MRI, patient did excellent. Here she is. The only deficit she has is a right sixth nerve palsy. She has normal hearing, that sixth nerve palsy disappeared at six weeks because the nerve was perfectly intact and atomically. Small price to pay to resect such a tumor. And the exposure that the posterior petrosal approach gives you is amazing. I think I'm gonna come back to it on another case to differentiate. Perhaps what some other neurosurgeons might choose to do this in a staged manner or a partial resection and gamma knife. I see no reason to do that in a relatively young patient. The other lesson, and this is not an original thought, again, I thank Harry Van Laveren who is in Tampa, 20 years ago to remind us that there is a lateral wall cavernous sinus lesion that is completely separate from the infracavernous sinus lesion. These are easy. These should be absolutely resected completely and not subjected to radio surgery. I will show you an example of what has happened with this 77 year old man who was being treated by another neurosurgeon before me. I'm not criticizing the decision because he was in his seventies. He did have radio surgery, but you can watch what happened to both tumors. You can watch what happened to them over time. Over the years, they did not respond to radiation and particularly the right one grew and became symptomatic. This one here. But look at this. This is a perfect example of the lateral wall cavernous sinus. It completely preserves the cavernous sinus and it's growing lateral to its wall. Very simple cases to resect through the Dolenc/Hakuba dissection plane, complete extra dural clinoidectomy. I did that patient, even though he was 77, went home post-op day five. Unfortunately, interestingly, I bet it wasn't the WHO Grade I originally, but it must have, it clearly turned into a WHO Grade II chordoid. So we treated him still with fractionated radiation after the gross-total resection. And I think, yeah, these will play, the pre-op and post-op to show you the complete resection of the tumor right here. Next lessen the orbit is often involved with the cavernous sinus meningioma. You have to master its anatomy. I have of course, a whole totally different set of lectures on orbital surgery and orbital anatomy. But you need to understand at least the orbital apex anatomy, if you're gonna operate in the cavernous sinus. And of course, the most useful approach is a cranio-orbital variant. So I'm gonna let the next video of three minutes 30 seconds play of this Spheno-orbital meningioma. It is playing it's a 62 year old female with rapid progressive vision loss. You can see on the left, the on plaque formation, we are doing an extra dural clinoidectomy left side cranio. You can see where S or F and the various other landmarks are. You can see the technique of some, I really don't like static retractors in general. I'm not saying I never use them, but I do use them but sparingly. But the technique of putting the neurolaw on the dura and holding the dura away, so you can drill with this low profile drill. You just saw it is, I love it because it is curved and therefore you can see the tip very well. It is covered by, it's protected all the way to the drill bit. So there is no chance of you catching something along the shaft. And here we are removing the so-called tools or the anterior clinoid to access the optic canal. We are going to then decompress the optic canal. We are going do some of the steps we discussed earlier. And we're going do the Hakuba/Dolenc peeling. The principle is to render. Here we go. We've done the peeling, V1 and V2 can be seen. The principle is to render this unplack as a sinus meningioma to make it a convexity meningioma. So that's why, and here we are, once you've done the Hakuba/Dolenc peeling, then you open the dural. I think it's an underutilized technique. I think perhaps non skull-based surgeons would have not done any of those steps and would have gone straight intraduraly and try to remove the meningioma intraduraly. The problem is you don't have a view of the third nerve and the fourth nerve. If you do that, you're bipolar may cause injury to those nerves. So that's why it is so much more expeditious, safer, more advantageous to do this, to do the extradural step first. You have a complete view of the third nerve, which you will see. There we go, you see the third nerve, I may have covered it with my green stuff, but it is right here. And if you have it in view, you know exactly how much cutting of the tentorium edge you can do. You know where the fourth nerve is and you will achieve truly a Simpson Grade I on what may appear at first to be maybe partially unresectable. But the Dolenc/Hakuba technique renders these cases completely resectable. And you have a nice view of the supraclinoid caratoid right here and dural substitute at the end. And that's the post-op and you can see the gross-total resection right here. Petro-clivo cavernous meningiomas. You can have a choice of retrosigmoid with retromeatal drilling that we talked about. But I would only utilize this if two things are happening, there is no significant medial fossa component and or it is my intention to do a subtotal resection. So, an example would be somebody like this. She is 35 weeks old. She has this left petro-cavernous meningioma. You will see it in a second. She has completely normal extraocular movements. She is a CEO of a company, a small company. Here is her tumor. She cannot afford and I cannot afford giving her an ophthalmo lesion. And I would, if I would be aggressive, probably on this case, particularly if it is of the texture that I expect it to be. So I decided in this case, all I need to do is the retrosigmoid and intentional partial resection, and do radiosurgery to the cavernous portion. That's a post-op. As you can see, I intentionally left this and this is nine years ago and this tumor has not changed in nine years after the post-op of gamma knife to this portion. And she has completely normal eye movements. When would I utilize an anterior petrosectomy, a Kawase or a presigmoid posterior petrosal approach in these lesions? So let's go over some examples. Kawase is the approach for a petrotentorial meningioma. We're gonna play that video. This is a pure Meckel's cave meningioma. A 63 year old man, healthy with an acute onset of sixth nerve palsy, no other deficit. He came to me, not much longer after his onset. what complicated, you can see the lesion on the right side. I'm not telling you the entire story. The other story is that there was suspicion of auto immune disease due to some blood work. So it wasn't entirely clear that it was a meningioma. So due to the unclear diagnosis, the acuteness of the sixth nerve palsy, you certainly don't want to gamma knife, an inflammatory lesion. And we did the CSF analysis and still wasn't clear. I decided to operate. So how would you operate on this case? This is perfect, in my mind for a Kawase approach. You can see the description of the setup that I use, the various monitoring, the NMES timulator, definitely a lumbar drain on all of these extra dural cases, otherwise, you will hurt the lumbar, I mean the temporal lobe. So what do we see here? Right side extradural approach. You can see GSPN, internal auditory canal and arcuate eminence as I showed you earlier in the anatomy. What am I doing with my NMES stimulator? You just saw a second ago. I'm looking for GSPN. You have to stimulate the geniculate ganglion, usually at about current 5 milli Ampere. And I will find it somewhere here and we're gonna cut the middle meningeal artery at foramen spinosum, as you can see here. I cannot overstress the importance of a lumbar drain. Here is GSPN. You can see it, right there. So again, as has been said many times, you have to dissect semi sharply from posterior to anterior. If you do from anterior to posterior, you can arouse the geniculate ganglion. Here is nice view of valley and V3. And obviously we know that because spinosum was just postural lateral to it. You can see the peeling. I hope those of you who don't do this often, this is an intradural peeling of Kawase of middle fossa from posterior to anterior. And once you have reached the petrous ridge right here, you can lay out the anatomy and understand that what we need to drill is the Kawase area right here. Behind V3, again, I remind you of the limits of the Kawase area, GSPN sorry, I'm gonna clear this portion. V3, GSPN, IAC, petrous range. That's why it's called a rhomboid rather than a triangle. So this is by the way, the true Petrous apex or so-called trigeminal depression. And this, those of you who read some French anatomy, we recognize as a tubercle of France sucto, This is a junction between false and true Petrous apex. Of course we're using navigation, but again, you can see the trigeminal depression. This is the tumor completely sitting in Meckel's cave, surrounding the trigeminal ganglion. And again, I schematized the various landmarks. Again, it would be really a mistake to open the dural now. Surround, as I tell my residents all the time, surround your enemy first, then launch your attack. So I'm drilling the not a complete Kawase drilling, but a partial drilling because I need to make sure , I'm not missing any meningioma deeper. And I need to get a little extra room so I can manipulate and move the trigeminal nerve. So I minimize the chances of the very unfortunate trigeminal dysesthesias that some patients can have, particularly if you've operated on some trigeminal schwannomas. These incisions can be almost worse than their original presentation. So I think the gentler you are with the trigeminal nerve and rootlets in removing a meningioma, the better the patient will be. So I've drilled as far as I felt is enough or necessary. And now I'm ready to open the dural along the fibers of the trigeminal rootlet and ganglion. And you can see that the meningioma is on plaque right here, or I guess really this way, this direction along the trigeminal nerve. And it's a matter of just peeling it off the nerves and minimize the use of bipolar. So we don't create a thermal injury of the rootlets or the nerve. And you can again, appreciate how infiltrative the tumor is. And it's a piecemeal resection. And I'm gonna chase it to the back of the true cavernous sinus. But had they not drilled partially the Kawase area here, I wouldn't have been able to really push this nerve back and forth to chase the tumor. As you can see, it's tracking along a V1 and V2 and V3, because this is the trigeminal ganglion right here. Very important. I don't know how to freeze this, but this is six nerve and Gruber ligament. This is, Oh, thank you. Thank you, Aaron. This is really, I had the schematic of it earlier. This is Gruber's ligament, where I schematized for you, how the sixth nerve is making a bend. I was looking for it. I was not using bipolar because, and we can play it, I think Aaron. Thank you. And that's right there. And of course I need to save it, as it transitions from posterior fossa into the cavernous sinus. Now I'm done, I remove the tumor. We are going to put some bone wax on some of the air cells in the Petrous apex that I drilled. And you can see actually how the temp, you can see the nice pulsation of the very relaxed temporal lobe because of the lumbar drain. And of course, because you lose CSF in Meckel's cave and that's the idea. We don't want to create a contusion. Dorello's canal, by the way, was first described in 1859 by Gruber and later by Dorrello. It's of course, anatomically important in understanding how you could create a sixth nerve palsy. So you have to look for it very carefully without the use of diathermy. This patient had the WHO Grade I, luckily, and the V2 numbness significantly improved at the last clinical follow-up. And I did give him a sixth nerve palsy that resolved post operatively by two and a half months. Pre-op and post-op MRI showing the resection. You can see where the tumor was. You can see why it's called really a Meckel's cave lesion, not a cavernous sinus lesion. Even though you clearly need to understand the cavernous sinus anatomy to resect it and some relevant references to this case. And next, so next let's do the opposite. Let's talk about what the suprameatal or reverse Kawase. When should we do a Kawase from below or a Kawase from the posterior fossa? Kind of a revival of the original Majeed Sammy suprameatal drawing. This is a 55 year old man, presenting with left V1 and V2 distribution numbness. No other focal deficits. The neuro imaging, you will see in a second. Right here, very small lesion, that's it. But it does enter the Meckel's cave area. So since it's primarily in the posterior fossa, you should do really a retrosigmoid approach But you have to really drill the suprameatal or bone, or really do the Kawase from below. If you're hoping to achieve a Simpson Grade I, and you will see why. So I like retrosigmoid approaches. I do them in the patient in the lateral position. I still like to do a C shape retro-auricular incision. And you will see the surgical steps in a second. This is, we said, it's on the left side. I always open the dural near cisterna magna. Of course the bone flap doesn't go down to foramen magnum. Every retrosigmoid craniotomy I do start like this. Always getting your CSF down below so that you have, you don't use self retaining retractors, you cut your arachnoid . You can see here a seventh and eighth nerve. You can see the lower cranial nerves with PICA and you march your way up. Just the standard retrosigmoid. And here is the tumor, right here. Now, of course, it's not always easy to see this angle, particularly if you have a large superior petrosal vein, which we don't in this case, you can see the vein is actually right here. So first I removed the easy part of the meningioma, but then here is the suprameatal tubercle that you must drill, otherwise, you're gonna miss half of the tumor hiding in the pores trigeminal. So once I've excised the dura of the suprameatal tubercle, then we're gonna drill it with my favorite drill, diamonds three millimeter. And I'm going to drill it flat. Flat, meaning until the tumor really finishes. Then we're gonna excise that, we're gonna excise truly the base, the dural base of the tumor. Now you can see I'm completely down to normal bone. This is the last piece of meningioma. This trigeminal nerve is now normal with no further meningioma on it. So that's the best Simpson Grade I, I could do. And here I am inspecting to make sure I have not injured sixth nerve at Dorello's canal. And I have not. You can see the sixth nerve right here. How do I go to the, oh, I guess, this is useful actually. So this would be the Kawase's approach. This would be the suprameatal tubercle. This is to compare and contrast the retrosigmoid with the Kawase from above, or so-called Kawase from below, Kawase from above. This is a Kawase from below. And I think the next slide will be a table comparing. So I want you to, I don't know if you can read everything, but this is comparing the, on the left is a normal Kawase on the right is the reverse Kawase or Suprameatal approach. You can see the structures, it gives you direct access to and contrast them. You can see which parts of the cranial nerves, each approach gives you the best exposure of. Of course, the normal Kawase is primarily extradural. The reverse is primarily intradural. The normal Kawase is a static retraction of the temporal lobe. The reverse Kawase is really a dynamic retraction. So the normal Kawase is primarily for middle fossa tumors with or without caudal extension to the posterior fossa. While the reverse Kawase is primarily for posterior fossa lesions with some extension of the middle fossa. So a tumor in window A or B, I would approach with a normal Kawase. But a tumor in window C here would be in my book, best approached through the retrosigmoid or reverse Kawase. This patient had complete resolution of their left facial paresthesias. And of course, it's a small lesion. But it's the point isn't the size of it. The point is you need to master it at that small tumor size. So you can really perfect it when you're dealing with much larger lesions. And the next case that I will show you, a combined Kawase Retrolab approach for petroclivocavernous meningioma . This is a little less than five minute video. I'm gonna demonstrate. By the way, when you see first authors on these videos, these are my wonderful fellows over the years. This was when Karolyn Au was my fellow a three years ago. So how do we handle this tumor? You can see it it's intra and extra cavernous, it's perhaps even involving the cellar. So we're gonna do a posterior petrosal approach. This is right side lumbar drain in, and you can see the NMES stimulator, identifying GSPN right here. Like I showed you in the other case, cutting of middle meningeal artery from back to posterior to anterior peeling to avoid injury of geniculate ganglion and doing maximum extradural dissection. We have a nice working lumbar drain. You can see the tumor. I am maximizing what I call the undressing grill of the tumor. You're removing, it's like a cap that you're removing off the tumor. The dura is a cap on the tumor. When you've done that, we have the beautiful view of the otic capsules intact. You see the two dural openings I talked about earlier, one here, one here in between. We are going to put work clips on the superior petrosal sinus, and then we're gonna cut the tentorium. And the question that is often asked by trainees is in what direction do you cut the tentorium? My answer is usually, here I just finished cutting the tentorial incisura. My answer is usually cut it in the direction that the Petrous ridge had before you drilled it. So you have to kind of remember how the Petrous ridge was before you drilled it with the retrolab approach, and then cut the tentorium that way, enter behind. By the way, this is OmniGuide laser that I use in this case, it's a handheld laser that is very handy in some really fibrous meningiomas. Think of it as both a knife and a diathermy device. Here it is again, you can see it doesn't have deep penetration, but it's very handy, particularly if it's in a deep area. So of course we're doing piecemeal resection. I've already identified the fourth nerve that I may have not have had a chance to tell you as we were approaching. And we've of course cut the tentorium behind it. And now I'm approaching into and towards the cavernous sinus, you can appreciate, I hope that is very fibrous. Here is the micro doppler. I'm looking for the ascending cavernous carotid. Because again, I will not achieve a gross-total resection in this case, due to the fibrous nature and the normal extraocular movements of the patient. And at one point between navigation and the doppler, I will stop in the cavernous sinus at some point where I feel I am just against the carotid. And here I'm very near that point. So now I am going to drill the Kewasi area. Again, remember GSPN, RQ with eminence and IAC is a bisector. And here we are a drill. Oh, the basal turn of the cochlea. Oh, I'm sorry, it's here. Basal turn of cochlea is here. I open now after drilling Kawase area, the dura of the posterior fossa to capture the petroclival portion of this tumor, very adherent. And there is no substitute to sharp dissection from the basilar artery, from the ponds, from the sixth nerve. And again, this very rubbery tumor, very nice view of the basilar artery right here. And again, had I not done the posterior petrosal approach, had I not combined it with the anterior petrosal, so here is anterior petrosal, sorry, I was too late in that for doing that, but there is anterior petrosal. The posterior petrosal is back here and you have the otic capsule in between. You have a nice view at the completion, preserved otic capsule, normal hearing. I'm putting a DuraGen on top. And the post-op, you can see what my residual tumor is. Is right here. Patient did very well. The rest of the tumor is all gone. It wasn't an easy tumor because of its fibrous nature. And now another case, a 60 year old, otherwise healthy male presenting with dizziness, ataxia memory loss. No other past medical history. Here is a little similar to this tumor, I just showed you. This is a very recent case. Look at how PCA is engulfed in the tumor. And here we're playing the MRI. You can see the supraclinoid carotid. You can see the invasion of the cavernous sinus. You can see how low the the tumor gets behind the clivus. And I am going to again, utilize my favorite approach for these lesions, which is the posterior petrosal approach, presigmoid, retrolab. And here is more views of that. Let me skip through that. It's showing you the lesion in coronal. You can see how it extends. There are some surgeons perhaps who would do an endonasal endoscopic. There are some surgeons who would do a staged retrosigmoid, and then come back trans-sylvian and so forth. I still don't like that philosophy at all. I don't think it works. I think you need to do your best with one approach that excises the tentorium. The tentorium is in the middle of this lesion and the only way to really have a complete control of the tentorium is through the petrosal approach. And we can let the video play. This is the left side. You can see the schematic at the top left where the incision is. The lesion was quite high, even though I normally don't put a retractor on these cases here, I needed to, to reach that portion that was quite high. You can see the fifth nerve. You can see Meckel's cave and you can see, again, a very fibrous tumor. Similar to the last case, I like to use these non-stick bipolars for these bloody fibrous tumors. And there is no substitute for patience for being methodical, meticulous. You don't want to rush. You want to stay focused. These are not quick cases at all. They will take several hours. I like to use the bypass. What I call the bypass forceps. You're seeing them right here. They're very fine. So when I want to catch a perforator or a nerve and tease arachnoid off it. similar to when I use them to do an anastomosis with a 10 or suture and so forth, I love using them for these very delicate maneuvers. They're so much more fine than the normal micro Bionet or bipolars or so forth. So for example, I'm catching this nerve, I'm doing traction, counter traction. We don't want to create a sub peel injury of the brainstem. They're very handy. Here is the basilar artery. Of course I have to be, here. sorry, here it is. I have to be of course, cognizant where the perforators would be coming out from. And obviously I cannot show you in two, three minutes, what has taken many hours to do? This is a SCA right here. Remember how it was engulfed on the MRI. So again, you have to just work around them. I use the crussac or the Sanopet, I'm sorry, this is a Sonopet. I use it not the whole time. I use it really when I'm comfortable that the piece of tumor I'm working on, has no important structures within it. It's easier said than done, but you just have to have a very good understanding in 3D of which portion of the tumor you're in. And of course, intra-op navigation is key. So, I don't know how you would do a case like this through just a retrosigmoid or even just a retrosigmoid and then you come back trans-sylvian, you will completely miss the hardest part of the tumor that's in between. And the basis of this tumor is in the tentorium. How are you gonna excise the tentorium? So here is at the end, the PCA, the SCA, the ICA, the tentorium that I've mostly excised. You can see the tumor entering the cavernous sinus, which I will still chase. That's not the end of the case. You can see the third nerve. So again, to really put the plug for the posterior petrosal approach, what is probably thought of is that, oh, well, it's more likely to injure the vein of Labbe when you do that. Well, yes, perhaps, but you have to be cognizant where Labbe enters. And Labbe is sitting somewhere, sorry, I missed it, but under the trollard. So I recognized it on the way in, and you put the surgery cell on it, and here is a fat graft at the end. And you close with the bone flap, with the temporal bone flap. And that's post-op. You can see how we really combined the retrosigmoid, which is here, the posterior petrosal and the anterior petrosal to achieve this gross-total resection. I wouldn't call it a Simpson I, it's probably a Simpson III. But you can see how each arrow has a better target volume that it can get. For example, the retrosigmoid gets you all the way to the clivus. You see, I'm sorry my line is not straight, it should be straight like that. The Petrosal approach, I can see might miss what's called the clival pit. So that's why you also need to add this angle of you. Sorry, it's a mess, but I'm sure you understood what I said. And that's post-op with a fat graft, and on your right post-op with fat graft. And I think that's it. I will finish with this case. What I call desperate tumors require desperate measures. This is an unfortunate woman who was my patient for many years. And she has a WHO Grade II, don't worry about the text. This text shows you I've operated on her. A number of times. I've radiated her a number of times, gamma knife, radio surgery. And now she's developing ophthalmoparesis, as you can see, a third nerve and a sixth nerve, but particularly a third nerve on the right side. And you will see her MRI in a second. I'm running out of options with her. As you can see, she's a young woman and we're showing her third nerve. The MRI, as you can see, shows the tumor completely engulfing the supraclinoid carotid, the cavernous carotid right here. And you will see on a sagittal. If the video is playing, you will see the coronal as well. You can see the supraclinoid carotid right here. It's engulfing it all the way to the bifurcation. So I tell this patient, and what I haven't shown you is the MRI six months before, it was a quarter of this size. So I told the patient, you know, the only way I can be radical is if I can excise you're carotid, I will sacrifice your anterior choroidal artery. I will almost certainly give you an anterior choroidal artery infarct. We did a balloon test occlusion, which she tolerated. And do you and your husband want to proceed? And she did, she and her husband. So of course it's a mess because I've been there many times before. You can see the scar tissue. So this is an example of the cavernous sinus exoneration for benign disease. It is a WHO Grade II. But it is after all benign, even though it will be the cause of her death, six years later after this surgery. So I have the neck exposed. The neck of the patient exposed. You will see in a second. I apologize that the video wasn't edited to size by me, so we will jump around in it. So what I'm doing here, I'm exenterating the cavernous sinus. Here we go. Now we can see the cutting of the trigeminal nerve posteriorly. And I'm surrounding the cavernous sinus. Here is the entry. This is ascending. I'm sorry, the middle meningeal artery. And we're gonna transect that, so we can separate the posterior portion. You can see transected, middle meningeal. You can see I'm going back intradural extradural. This is Meckel's cave, right here, you saw it briefly. The trigeminal rootlets scar tissue being cut. I need to get access to the supraclinoid carotid artery and the bifurcation. And here now sharply dissecting the M I. Removing the easy part of the tumor. My goal, what is my goal here? My goal is to identify the supraclinoid carotid the bifurcation. Put an aneurysm clip across the ICA just below the bifurcation. And then transect that, transect the cavernous carotid and resect everything in between. Here is again, trigeminal nerve. Again, you can appreciate how fibrous it is. Here is the bifurcation. This is A one. This is M one, and this is the carotid in the neck. And you saw me earlier, here we are measuring the flow in the M one with me putting a temporary clip in the neck. And when I was satisfied that there was very good flow from the A one to the M one, I put this clip. You can see right optic nerve, and you can see that using the previous BTO and using intra-operative flow measurements, I was comfortable that I will not give this patient an MCA stroke by transecting the carotid. So now I have, I can be much more aggressive. I have a clip on the ophthalmic artery. I have the clip that I showed you on the carotid above the anterior choroidal. So obviously the pcom and the anterior choroidal, are being sacrificed. And now there is really nothing more to fear. There is nothing more to preserve, everything between the petrous carotid and the carotid bifurcation will be exenterated. So you will have in a second, perhaps a view of the cavernous carotid. These are pieces of tube coming off. You can see trigeminal nerve, trigeminal ganglion totally infiltrated by tumor. I am transecting it. You know, we don't often. I certainly always cringe when I cut any nerve intentionally, no matter what the function of the nerve is. And this whole mass is tumor with engulfed carotid. Here is the foramen lacerum with the carotid artery going up this way. And I'm putting heavy seal in the, for the venous bleeding around the carotid artery. Of course, the carotid has not much life in it since ligated it in the neck, but I still need to cut it. And there are some cavernous sinus collaterals, meningohypophyseal trunk, inferolateral trunks, that could be the source of some back bleeding. Here is the horizontal carotid artery. Oh, very nice view of the sympathetic plexus on the cavernous carotid artery. Very nice view of the meningohypophyseal trunk right here, that I am just cutting and, coagulating and cutting so that I can actually resect the tumor portion. Then I'll go after the carotid. This is the junction of the ascending cavernous and horizontal cavernous, ascending caverns. We're gonna cut the carotid itself. And pretty much the surgery is done. And I think we can go to the end of the video. Look, the final view. There is the basilar artery at the bottom. The brainstem right here. You can see my clip across the transected carotid. Now I have to chase. I misspoke earlier, of course, there is still more to go, but there is this tumor that I'm chasing towards the chiasm, under and medial to the anterior choroidal artery. Again, peeling it of the brainstem and using the Sonopet for the final few pieces. Okay. And that's at the end. AlloDerm, fat graft, and I will show you the stroke, the expected stroke. I'm giving this patient that we talked about extensively pre-op. You will see the classic, by the way, this is all fat. The tumor is truly completely gone at the cost of the following stroke. Oh, I guess it's in the slide after the video. I apologize. Whenever I will see, here we go. Here is the infarct. The patient was hemiplegic for a few weeks and I don't have her video to show you. But she completely recovered at four months. This woman lived six years before this nasty WHO Grade II came back and actually was the cause of her death in her late forties. But I do think that this aggressive surgery actually did improve her quality and quantity of life for six years and she was clearly going to perhaps die that year of when that tumor exploded. My conclusions about the cavernous sinus lesions. In general, here is what is fiction. It is not true that all cavernous sinus lesions are created equal. It is not true that location trumps the pathology, it is a pathology that trumps the location. It is not true that cavernous sinus is inaccessible. It is not true that surgical morbidity is always certain when you operate in the cavernous sinus. Cavernous sinus surgery is harder and riskier. But it is perfectly okay to profile tumors in the cavernous sinus. It's not a dirty word when you apply it to cavernous sinus pathology. The lateral wall is not intracavernous. There is no substitute for experience and judgment, they feed off each other. Again, a summary of the various approaches that I might utilize to the cavernous sinus. This is not just meningiomas, but in general, I really mentioned my philosophy. Here we are using the word philosophy, earlier the talk. And we really do have to recognize many pioneers, but particularly this guy sitting next to me, Vinco Dolen when we were teaching courses in Helsinki for what he has done to the cavernous sinus anatomy. And I am sorry, I can see that I am way over time and I apologize. Thank you very much.

- You know, you really have been truly such a leader in education and leadership and it shows. We have so many lectures usually for the series we've been doing for so many years. There are very few who are as enthusiastic and passionate about teaching and good technical skills. And it really shows Jacques. We're so proud to have somebody like you in neurosurgery and so much who have contributed in training of so many neurosurgeons across the years. It was a little bit long, but it was all great stuff. So never can complain when it's all good teaching. And I really, really appreciate it. For the sake of time we're gonna, don't do any more questions, I wanna truly thank you for really an incredible set of technical presentation that's so important for managing these extremely challenging lesions. I wanna live, however, with one just question and that's monitoring. Could you tell us Jacques, about your preferences regarding intra-operative monitoring?

- Yeah. Thank you, Aaron. I do utilize, cranial nerve three, four, and six monitoring. To tell you the truth, it's not so much to know where those nerves are, but once you know where they are to make sure they're still quite sensitive to NMES stimulation. I don't necessarily utilize SSEP or MEP when I'm operating on cavernous sinus lesions Unless I know that I'm gonna get very close to perforators of the brainstem or may have to deal with carotid sacrifice and so forth. So it's mostly lower cranial nerve monitoring. I have not monitored the fifth nerve. Oh, by the way, we certainly need to monitor seventh nerve and eighth nerve when we're dealing with the middle fossa. I know you, I think you do or maybe others monitor the fifth nerve. I haven't, it's such a big nerve and it's so easy to find that I don't bother.

- With that I wanna really thank you again Jacques for being such a great contributor in series and look forward to having you with us again in the near future.

- Thank you and apologize for being too long. And I congratulate you for all these series of lectures you're putting together.

- It was great stuff. You know, nobody can argue with amazing value and doesn't matter how long it takes. Just like the surgery, it doesn't matter by the time, it's the outcome that's most important.

- Nicely said goodbye, everybody. Thank you, Aaron.

- Thanks you.

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