Transcript

- Colleagues and friends, thank you for joining us for another session of the Virtual Operating Room. Our guest today is Dr. Samy Youssef from University of Colorado. He's a Professor of Neurosurgery Otolaryngology there, as well as Vice Chairman of Education and Director of Skull Based Surgery. He's truly a star in microsurgery, as well as skull-based surgery, and it's an honor for me to introduce him today. He will talk to us about management of very difficult lesions, the petroclival meningiomas, most likely the most difficult lesions we managed in neurosurgery besides arteriovenous malformations. These tumors are daunting at times, and their technical skills required to manage them are immense. So Samy, I'm very much looking forward to learning from you, and please go ahead.

- Well, thank you Aaron. It's an honor to be invited by you to contribute to your prestigious venue here. And I have to give you credit that you started this way before Zoom and COVID and all that stuff. You know, it's been decades, probably more than a decade that you've been doing this, so. And I always have the impression that if I get invited then that means that my work is credible. So, thank you again.

- Thank you, thank you.

- As Aaron introduced to the subject today, petroclival meningiomas are really the, one of the most difficult lesions that we deal with in skull-based equivalent to basilar aneurysms in vascular surgery, equivalent to scoliosis in a spine surgery. So it is the challenging one that requires lot of training and experience and flexibility, as well, of what you can choose tool-wise to deal with them. So quick review of petroclival region. Anatomically, it's, as you see here, we have a lesion that's centered over the petroclival junction. And the petroclival junction, if you look at this anatomy here, so it's anterior to the trigeminal nerve, it's anteromedial to the seven and eight, or IAC, and it's cephalad to the jugular tubercle that I just pointed out here. And as you see, these are different lesions, but they're all at the petroclival junction, and they're all meningiomas. So these are the examples of lesions or petroclival meningiomas that are most challenging that we see in this region. So, quick review. this is of course, you know, a review of different series of famous neurosurgeons and experienced neurosurgeons in a skull-base. And as you see, that the gross total resection rate is 20-40%, mortality up to 9%, morbidity high up to 39%, and permanent cranial nerve deficit, 17%. That's really a high price for what we do for these lesions. And, of course, recurrence rate, 42%. So, traditionally, these lesions have been approached through a lateral approach or open lateral approach. The way we look at this anatomically is we divide the clivus into thirds. Upper third would be between the IAC, a plane above the IAC plane, a middle third between that zone one and zone two, and the lower limit of that would be the jugular foramina. Then the lower third would be lying below that, the foramen magnum. So when we divide this into thirds, we're able to choose the approach depending on where the lesion is centered. The lesion like this, for example, you see it at the lower third of the clivus, that's zone three and that would be like a foramen magnum meningioma here. So a far lateral approach would be obvious for these lesions. So we get that out of the way, that's a straightforward choice. Now we come to the upper third. For this, traditionally, we've been doing the anterior petrosectomy to take the petrous apex off and get to a small lesion like this at the upper third as long as it doesn't cross below the IAC. Now if the lesion was below the IAC or it's like here and it's zone two, posterior petrosectomy would be either addition or if the lesion is just centered at that mark here at zone two, then we'll be doing a posterior petrosectomy. And my issue with the posterior petrosectomy that it gives you that narrow deep corridor anterior to the brain stem to get here. And, of course, you work between the cranial nerves here, and your angle is small and limited by the labyrinth. If the patient can hear, then you don't do translabyrinthine approach. So let's take an example of this lesion here, another petroclival meningioma. It's almost tackling the middle third, but it's also going anterior all the way, as you see here, to the anterior fossa, almost to the medial sphenoid wing, anterior clinoid. So for this, we do what we call the pretemporal transcavernous anterior petrosectomy approach, or the combined Dolenc Kawase. And it gives you that nice exposure here, so you can get the lesion to the lower part of it, and you can get up all the way to the optic apparatus and even decompress if the tumor is going to the optic and there you can decompress the optic nerve. So if we look at this in the video, an example for this lesion is pretemporal transcavernous anterior petrosectomy approach, or the PTAP. So here is the first part of the exposure, that's the temporal orbital ligament here that we're cutting, mobilizing the lateral wall of the cavernous sinus in this direction. And this is the anterior clinoid process here that we just exposed. So without mobilizing the lateral wall of the cavernous sinus, you won't get to the tip of the anterior clinoid process. Then we're drilling the anterior clinoid and thus decompress the most anterior part of the tumor, the orbital apex, so decompress the optic nerve. Here you see the anterior clinoid is being removed. And that's an extradural phase. So, we'll finish the extradural phase all at once. Extradural anterior clinoidectomy decompress the roof of the cavernous sinus, and, as you see here, the optic strut, we're flattening that. Then we'll go to the top temporal part. So, this is here, that's the middle fossa. We're lifting the dura off to expose the, here is the GSPN, and that's the V3. So we do that, intradural mobilization, we call that the Kawase technique, from below up mobilization and expose the petrous apex. Then we do the anterior petrous resection, or anterior petrosectomy, so all that extradural. And we stay in the middle fossa, then we open the dura, so along the temporal lobe here, and below at the posterior fossa. Then we straddle the superior petrosal sinus in order to ligate the sinus, and between the hemoclips. Then cut the tent. So when you cut the tent, be very careful of where the trigeminal nerve is, right there. So that's the trigeminal nerve root here. This is a true petroclival because it was pushing the trigeminal nerve root laterally. And the second structure will be here. So that's the trochlear nerve. We have to expose and preserve trochlear nerve and keep working between these two nerves. So the tumor is already expanding that intradural and we're working between these two nerves for now. So we got the trigeminal nerve cleared, we're working now going below to take advantage of here, that's the anterior petrosectomy intradural and debulk the tumor. So you see I'm retracting on the trigeminal nerve root here to get below that. So that's going down to the posterior fossa. And the beautiful part of this approach is you can look directly at the brain stem here and mobilize the tumor from posterior to anterior taking advantage of all that exposure that you have. Now this is the third nerve you see the third nerve is tented all the way up like this by the tumor. So we have to bring the tumor down from the trochlear nerve from the ocular motor nerve. And you see these vessels here on the nerve. This have to be preserved in order to preserve the nerve functionally. Debulking that tumor and again clearing the nerve moving it up, and that's the final result of that. Okay, so that's the residual here as you see. That central clival residual and I'll come to that later in my presentation, but all this tumor is gone. So the lateral part has gone through that combined approach. Now this is another example of a patient that if you look here, have this tumor. This is a recurrent meningioma. So initially it was done through a translabyrinthine approach and you can see the fat pad here after its posterior petrosectomy translabyrinthine approach. And the tumor was WHO1 but had some atypical feature on the three months follow up that was the tumor. So it came back bigger. And if you see here, this part of the tumor is behind the petrous apex and we already did the posterior petrosectomy. So we are gonna add an anterior petrosectomy to what we did before and do what we call the combined petrosectomy or the kidney shape craniotomy to get this exposure except that the labyrinth part will be gone from the first exposure from the translabyrinthine. So we'll take advantage of having this part off and that's the combined petrosectomy for this case. So here is the video for that case. And again, you know this is the horseshoe. So we expanded, we extended the incision all the way anterior pretemporally and took the temporal craniotomy off in addition to what we had before. And same, we're lifting the dura up from the floor of the middle fossa and this is the foramen spinosum. We got the middle meningeal ligated and the GSPN and you see the navigation here. Then we do the anterior petrosectomy. But here the difference is the posterior petrosectomy stops right here. So this is almost like a transcochlear approach because we're, or total petrosectomy approach. So we're gonna be drilling the IAC here like an expanded middle fossa approach and connect the posterior petrosectomy with the anterior petrosectomy. So here we're drilling the IAC. You're gonna start seeing the, the soft tissue of the cranial nerves extradurally, stimulating the facial nerves through the dura and connecting the two exposures together. Same, open the dura here, but again the trigeminal nerve will be different depending on where the tumor came from. Is it a true petroclival or tentorial or petrous face. So every time you're opening the tent like this, you're gonna have to be careful about the two structure. Right there will be the trigeminal nerve root and on the other side will be the trochlear nerve. So opening the posterior fossa dura here and it's all tumor as you see. And to straddle the superior petrosal sinus which is right there. Ligate the superior petrosal sinus between two hemoclips. You see that big draining vein here from the temporal lobe, bridging vein. I'm preserving that. Hopefully it's draining away from the superior petrosal sinus or anteriorly and it will be reversed. So now ligating the rest of of the superior petrosal sinus and connecting the two exposures together, supra and infratentorial. Now I'm looking for the trigeminal nerve root. Unlike the previous case, the trigeminal nerve root was clear. Here we still have to do some work to find it. So this is the tumor here. So now a little bit of debulking, looking for that trigeminal nerve root to the porus trigeminus. And right there we're gonna start seeing some nerves. And that's the trochlear nerve right there. So if you keep this arachnoid intact, you would never injure that trochlear nerve on the other side of the tentorial edge or the tentorial hiatus. And right there you see I'm digging tumor to get into the the plane with the trigeminal nerve root. Here's the trigeminal nerve root. Very important to know where the trigeminal nerve root is and almost like a see through technique then sharply clear the nerve root from tumor. So this is just taking advantage of all that petrosectomy exposure and go below the trigeminal nerve root and we will start seeing some pontine and prepontine structures. Still trigeminal nerve root here, dissection. And we start seeing the six nerve down and we'll see seven and eight posteriorly here, right behind this tumor. So this is the fat by the way from the previous exposure and the fat will be very, very stuck. It's very important also to use sharp dissection and helped with a press probe to dig the facial nerve back here. So here are the prepontine tumor resection and you can see the six and seven nerves. And now we're moving back to the posterior petrosectomy part. So this is the anterior petrosectomy and this is the posterior petrosectomy and we're following the tumor to get in a horseshoe fashion around what's left from the petrous bone. So it's mastoid, like the tip of the medial edge of the mastoid. And that's mix of tumor and fat that we're resecting now. So digging the facial nerve out of this fat is not fun. It's really challenging task and that's why I'm using sharp dissection right there and the facial nerve, we'll see it shortly. Again, keep splitting this tumor and fat to get to the facial nerve. That's trigeminal, then we'll see the facial nerve shortly. We'll be in the middle of, in the middle of this here. So right there. That's the facial nerve, right there. So as you see, I mean the, very stuck to the nerve. This patient started with House-Brackmann III and woke up from this surgery with House-Brackmann VI. But came back, his vision nerve came back to House-Brackmann III and can close his eyes and is pretty much functioning with House-Brackmann III given all these challenges. So that's the final like exposure or after resection of the tumor we put DuraGen and fat in the posterior petrosectomy part and close that. So that's combined petrosectomy for this previous small tumor. Now what about here, this tumor there? So this is what we call petrosphenal cavernous tumor. It's going all the way anteriorly involving the Circle of Willis, the cavernous sinus and petroclival region here. And the question is, did what we just do in the previous case work for this one, combined petrosectomy for this extensive tumor? We again, as I mentioned at the beginning of my presentation or my videos that I have reservation against the posterior petrosectomy especially if it's retro-labyrinthine, that it gives you this narrow exposure. So we did this combined work with BNI, Dr. Labib, my fellow last year and we did compare the combined petrosectomy to anterior petrosectomy and what the posterior petrosectomy adds. Like if you add the posterior petrosectomy here to the anterior petrosectomy, how much does that give you? It gives you no difference below the pontomesencephalic junction, except for like above pontomesencephalic junction. But below that would be the advantage as expected and it gives you that lower clear nerves exposure. So nine through 11 additional exposure through that narrow window. Which brings us to that central clival part, which always below the pontomesencephalic junction here that we wanna get to through the posterior petrosectomy approach. Can we use one of the endoscopic approaches to directly get to that without working through the narrow corridor across the cranial nerves from posterior petrosectomy? So let's see what you need to do for that. So here's the petroclival meningioma. Would a central skull-base approach work? No, so you need an expanded lateral skull-based approach. What does that entail? It entails that you go through different hurdles. Superficial hurdles, which is nasal and paranasal structures and the deep ones, which are four main structures: pterygopalatine fossa; vidian nerve; the ICA, horizontal, anterior genu, and vertical segment; and the eustachian tube. These are very strategic structures to go over. So that approach would be a transmaxillary transpterygoid approach. And once you do the transmaxillary part, you get to the posterior wall of the maxillary sinus, you will have to expose the transpterygoid process and the medial transpterygoid plate here and expose the the pterygopalatine fossa. And you're gonna mobilize that laterally and that's by dividing the vidian nerve, vidian nerve at the vidian foramen and drill the vidian canal all the way to the lacerum segment of the ICA, then mobilize the eustachian tube in order to expose the petrous apex and the clivus. Really significant technique or maneuvers, very, very demanding and you have to be very well acquainted with lateral skull-base endoscopic anatomy. With all that mobilization of the carotid you would get a five millimeter as I'm showing here, five millimeter additional exposure, okay. Then when you get to the fibrocartilaginous tissue here, you have to really resect all the tissue in order to get that intrapetrous supra eustachian corridor. And that requires a sacrifice of the middle portion of the eustachian tube, short of the torus tubarius. We did another alternative to that, Dr Labib as well, was doing that in the lab last year, of mobilizing the eustachian tube. So with that you mobilize the eustachian tube instead of inferior, you mobilize infralateral, anterolateral as you see in this art here, and that will give you that trajectory more to the lateral skull-base and down to the jugular foramen. We did that in cadaver only, so we haven't done that in any living specimen or real surgery, so we can't really judge its efficacy yet, but it's an option. But if you take all that into account with mobilization or resection of the eustachian tube based on the carotid, this 3D construction show you that window to the petroclival region through anterior petrosectomy. And that window is 1.5 cubic centimeter, okay. If you look at it in a 3D reconstruction of the petrous bone by itself, blue is without mobilization of the carotid or eustachian tube. The red is after mobilization of the carotid and the yellow, let's see here, this yellow is how much petrous apex you're gonna resect after you mobilize the three structures: the pterygopalatine fossa, the eustachian tube, and the carotid artery. So that's the anterior petrosectomy that you do endoscopic. And the intradural window, when you do this transpterygoid, transmaxillary or transmaxillary, transpterygoid exposure to the petroclival region, this is pretty much the window. You can expand that window by taking more clivus off, but you're limited here at the anterior petroclival region to the most anteromedial CP angle or petroclival region, and that's pretty much the intradural window. So, large lesion like this, you cannot rely just on endoscopic approach to the petroclival region. That's clear, and that's all shown by what I just presented anatomy wise. So if you compare, so what if we add, so we don't do endoscopic exposure by itself, but we add that to what of that combined Kawase Dolenc without posterior petrosectomy in order to get to that anterior brain stem directly without going through cranial nerves. So when we compare these approaches, the combined petrosectomy to combined endoscopic and pretemporal, we got pretty much the same exposure of the cranial nerves, so that's, but as expected, the six cranial nerve, you get more exposure endoscopic, so that was an advance or disadvantage I would say because the six nerve is still vulnerable during our endoscopic approaches. But if you compare mid-brain pons, you got way more exposure of the anterior brain stem or ventral. So that's as expected. And when you look at the lower brain stem, which was the posterior petrosectomy give you that advantage, the exposure of the medulla and clivus was way more on that second option combining endoscopic and anterior petrosectomy by itself, dropping the posterior petrosectomy of the equation. So how would we apply that to a tumor like this one here? So this is what we are proposing. We're proposing that we do this. This art was created by Neuropub art illustrators. Great work. And this is still in publication process. So you combine the endoscopic anterior transpterygoid and a lateral, as you see here, that combined Kawase Dolenc. So that's the Dolenc part here. That's the Kawase part there. You get that beautiful exposure laterally to take the lateral part of the tumor and stop shortening down blindly ventral to the brain stem below the IAC, then come back and do the endoscopic approach to get that beautiful anterior exposure away from cranial nerve. The only cranial nerve that will be in your way will be the sixth nerve here. So that's stage one as showed in this previous tumor. We pretty much took the lateral part off and that's the central part. And you see the tumor is pointing into the sphenoid sinus. You know, it's already leading itself to an endoscopic approach. So we do the pretemporal anterior petrosectomy approach first, then we go back and do the transpterygoid for the central part. And that's the final here. That's preoperative, postoperative. So it pretty much took the lateral part through a lateral approach, the central part through an endoscopic approach. And we left, this tumor was in the two cavernous sinuses, So we left that alone, and the retrocellular part might be there because I don't mobilize the pituitary for these tumors. 'Cause if you're gonna leave tumor in the cavernous sinuses, you might as well just leave the connection between them below, behind the scilla. So if we look at, let's see here. We call that the staged PTAP/EEA approach to the petroclival region. And I'll go through this video with you. So the first stage will be the open lateral approach. This is an extensive tumor as you see here and we call that the 360 approach to the petroclival region. very extensive tumors, and that's tentorial by the way, tumor. It's going along the tent anterior and posterior, but also involved in the petroclival region. So a cadaveric illustration of our exposure. Expose the anterior clinoid extradurally and mobilize the lateral wall of the cavernous sinus. Then come back and finish the extradural Kawase part. So that's the real surgery now. This is what we are gonna resect through for the Dolenc lens approach, anterior clinodectomy extradural and here exposing the optic nerve. Then flattening the optic strut. And now we move back to the middle fossa extradural so we don't open the dura and we will do the Kawase part of the approach. So we did the Dolenc first extradurally, and now we're doing the Kawase part. So anterior petrosectomy, so here's the IAC. We didn't expose it. Patient, this patient can hear, so we didn't really mobilize anything there. And here is what I showed earlier of the supratentorial, infratentorial opening the temporal dura above. So this case, as I mentioned, is a tentorial tumor over the entire tent, so you one get this luxury of normal anatomy to cut the tent so you have to debulk tumor before you get to the tent. And being a tentorial meningioma the trigeminal nerve root will be a little tricky. So we have to really dig for this nerves again. So keep resecting tentorial tumor until we see some anatomy, and that's the trigeminal nerve. See that trigeminal nerve is going in the middle of this tumor. And again, we'll because it's not a true petroclival, so we'll have to really understand the pathological anatomy or abnormal anatomy here. So that's the final resection after the Kawase part. Then we'll move anteriorly after this and open the dura of the anterior, anterior fossa to get down to the trigeminal. So this is finishing the lateral cavernous sinus part by resecting the extracavernous tumor with the dura. So that's the outer wall of the cavernous sinus just came off and work different trajectories to get tumor from around the carotid and the carotid, the carotid oculomotor cistern. As you see here, we're resecting tumor between all these structures as much as we can. So that's the intradural portion of the Dolenc. And that's a supraclinoid ICA. So that's the final exposure or final result after the lateral exposure. Now we move to the central part to get to the anterior petroclival region and we do that transpterygoid approach. So here is maxillary antrostomy. So this is the back wall of the maxillary sinus and following the sphenopalatine artery to the sphenopalatine foramen here and start resecting the perpendicular plate of the pterygoid, of the palatine bone. And in order to expose the vidian foramen as you see here, so this is the vidian canal, the vidian foramen, we're ligating the vidian vessel artery and vidian nerve and mobilize the pterygopalatine fossa content laterally. And now drilling the anteromedial part of the pterygoid, of the pterygoid process and vidian canal. And that will expand all that superficial corridor to get down and manipulate instruments in that central part of the exposure. So this is the transclival portion now. So we're not mobilizing carotid or eustachian tube, we're working in between and debulking the tumor until I see brain stem. Then I put the Cottonoid on the brain stem and find the plane as you see here, you'll see, yeah, right there. So that white portion is the pons and work directly between the brain stem and the back wall of the tumor. Right there, that's the brain stem. And go behind, so again, I'm not mobilizing the pituitary, I'm working behind the pituitary. 'Cause again gross total resection is not the goal here. It's maximum safe resection. And delivering tumor, this Cottonoid is on the brain stem, and working behind the pituitary gland, right there, coagulating the dural edges between the two carotids and constructing the posterior fossa exposure with the fat graft and nasoseptal flap. So this is the final product of this approach. So we left the cavernous sinus part here, the cavernous sinus part there. So in light of this multitude of approaches, we expanded our algorithm for managing petroclival meningiomas. So if the tumor is extending posterior to the IAC or lateral to the IAC, a retrosigmoid approach can still do the job if it's medial to that, it's a true petroclival, and we have, we have upper third as I mentioned earlier, we do anterior petrosectomy middle third, posterior petrosectomy combined for upper two thirds. But if we have sensorineural hearing loss, hearing loss, then we can add a translabyrinthine part to the posterior petrosectomy and take advantage of that space. But if we have intact hearing, again the posterior petrosectomy retrolabyrinthine approach will be limited. And we can replace that with an endoscopic endonasal far medial approach. Lower third, as I mentioned, far lateral approach and if it's anterior and or middle and posterior fossa, we can do the pretemporal anterior petrosectomy approach. If it's an extensive tumor like the last one I just showed, then we can do a combined or stage the pretemporal and endoscopic approach and do the staged approach to that. Now what do we do for the residual? If it's WHO, I like to watch those if there is no atypical features. That gray zone of atypical features with WHO1, I still would radiate that. But two or three of course will follow with radiosurgery. So here is an example of how the retrosigmoid an still be used. The 41 year old lady and like so many Colorado citizens or residents, marathon runners, hikers, mountain biking and climbing, so they're pretty active outdoor people. And that lady just came complaining of dizziness, nothing in nerve deficits and she had that tumor that starts at the petroclival region but extends back lateral or post lateral to the IAC. So we elected to go retrosigmoid because the tumor is just extending all the way posteriorly. So retrosigmoid can still do the job here. Okay, so we call that a CP angle more because it's extending the CP angle posteriorly here, so a simple retrosigmoid. And the trick about this meningioma is that they're not true petroclival, there can be tentorial. And with tentorial meningioma you're gonna have to dig for the cranial nerve. So unlike acoustic neuroma for example, where you have fixed position for seven and, for eight, and seven can be one of three positions, here you have to really dig in the middle of this tumor to find those nerves. So be very careful with the CUSA or the SONOPET when you go through these tumors because the nerves are in the middle. I'll show you that shortly. So here I establish some anatomy with seven and eight nerves and I'm working suprameatal intradural. The second nerve to locate here will be the trigeminal and it'll be deeper, but here's dissection from the petrous face and devascularizing tumor. Then go back to debulking. The three D: devascularization, debulking, dissection. And be very careful here. Here we'll start seeing more neurovascular structures. So working the suprameatal space or segment, the trigeminal nerve root will be next. Tumor is kind of soft, which is an advantage for these tumors. And so here is seven and eight. Lower cranial nerves, next, so I'm working below the seven and eight nerves monitoring all these nerves, of course. There's a branch of ICA. And see how the tumor is deep or anterior, so it was posterior and anterior to the nerves. So the nerves are in the middle of that. So the nice thing about the retrosigmoid, it's giving you that enormous or generous space to work within and now sharp dissection and key there is the cochlear nerve, we just saw that and the facial nerve. Keep the arachnoid intact on vasa nervorum to keep these nerves functionally working after resection. So now carefully working anterior to the seven and eight cranial nerves, bringing tumor up to the suprameatal intradural, and now we're gonna move all the way to the trigeminal nerve looking for it, which is, should be shortly here showing. And now this stump in Meckel's cave, so there is a stump of the tumor in the Meckel's cave, as you see the trigeminal nerve here is surrounded by tumor that I elected not to go and dig further into that. But that doesn't mean that there are no options for this. So if you have this Meckel's cave tumor, you can still approach it through a retrosigmoid approach and that's what we call the RISA. So let's move to the next slide. So the RISA, the retrosigmoid infratentorial suprameatal approach for a tumor like this, so this is lady that has multiple meningiomas, I resected a big CP angle tumor here. She had radiation as a five year old for another tumor and now she's developing all this radiation induced meningiomas. So we followed this small tumor and it grew and the patient presented with six nerve palsy. Still a keyhole retrosig will get you there, so you don't have to go anterior and do the retrosigmoid anterior petrosectomy Kawase approach, 'cause the tumor is pointing into the suprameatal space. So you can approach that through a retrosigmoid approach. So here's the video for this case. Dom is our current skull-base fellow and he edit that video. And just a quick history of this lady that I just mentioned. So the six nerve was really disabling in this patient and we decided to go because the tumor progression of course, the suprameatal infratentorial approach. So here is the reverse Kawase as some people like to call it, of resecting the petrous apex from a retrosigmoid suprameatal approach. So this is the suprameatal intradural here. And that's tumor, and we we're expanding the margin around the tumor by resecting part of the petrous apex through the posterior retrosigmoid approach. So diamond drill. Looking for the trigeminal nerve at some point. And I think I did preserve the petrosal vein in this case. You can see some vein at the end. But debulking of the tumor and get to begin to see how much more I need to do of anterior petrosectomy through that approach. So right now disconnecting the tumor from the porus trigeminus Meckel's cave and bringing it back to the retrosigmoid exposure. So there is still some abnormal bone here. And now you can see the trigeminal nerve root and the portio minor. And keep this arachnoid intact. That's good for the nerve. And keep mobilizing this tumor extractor. Now you can see the trigeminal nerve root. So cover that with Cottonoid. Preferably you put gelfoam not Cottonoid when you're drilling, but I was very cautious here using the diamond drill. And just keep finishing that exposure to get to the anterior, most anterior extension of this tumor in the middle sphere. Now these are curved curettes that we have in our set and they allow us to do this extra extension of our resection. So use these angled curettes. Trigeminal nerve root is down here, covered with Cottonoid, so I'm pretty comfortable doing this. And we're gonna keep resecting that last portion of the tumor until we feel that we got it all. And that's the trigeminal nerve root here. So keep working and delivering this last pieces of tumor. And at the end you see that small keyhole craniotomy that we did this exposure through. We didn't have to do middle fossa or anterior petrosectomy Kawase approach for this. And the hemostasis as usual with the Surgicel. And can see the cerebellum here, arachnoid is still intact and that's where we get the tumor through, right there. And as we do with the anterior petrosectomy through the you've gotta wax all these hair cells to avoid CSF rhinorrhea in this case. So we have to really be meticulous with this part as well. Waxing and make sure you block any access to CSF. So same exact thing as the anterior petrosectomy through the Kawase and reconstructing the dura. I think we have the... So to finish with another example of extensive tumors. So we have this tumor that's going posterior to the IAC and anterior and going all the way up to tentorial hiatus and expanding posteriorly. So we decided to go staged, at least retrosig first. So we got the retrosig, got tumor was very stuck to the brain stem, so we stopped short. That patient had multiple cranial neuropathies pre-op, she had House-Brackmann IV, lower cranial nerve palsies. We had feeding tube to the, before even surgery. So we were left with this residual. And in the three months though it was grade I, no atypical features. And in the three months follow up look the tumor came back. Like all of it. So this tumor had lost hearing before surgery, had House-Brackmann IV and had this tumor completely extending anteriorly and posteriorly like this and centered over the petroclival region and was lost hearing, and this deficits we decided to go transcochlear. So as you see from this art here, the more anterior you wanna go to get this tumor off, the more petrous bone you're gonna resect. So resected with total petrosectomy. Transcochlear and the facial nerve was mobilized because it was in the middle of tumor and you were able to resect it, near total resection with this approach. So that's another combination of approaches, another example of combination of approaches. So in the end, petroclival meningiomas be focused about the cranial nerves anatomic and function preservation. Be open minded about combining a smaller approaches rather than two big approaches. Maybe it will get you better functional outcomes. And to reemphasize the modern scopic surgeon should be skilled both in open and endoscopic approaches. And that would be my final conclusion. Thank you for your attention today. And Aaron, I'm open to any questions.

- Beautiful lecture.

- Thank You.

- Beautiful lecture, Samy. Really enjoyed it. Really proven yourself a true star in skull-based surgery.

- So proud of you.

- Thank you.

- I've been following your career for so many years Samy, and really incredible work. Incredible work. And you did it really all on your own. And that's the value. You know, a lot of neurosurgeons may have mentors who sort of have them come in and take their place and so they get a lot of lift without doing it. But you did it all on your own and that's so respected. It's truly your value rather than somebody else's.

- Thank you so much for this golden words as I would say.

- Well it's the truth. And so one thing that I wanna bring up that you mentioned very beautifully, is that don't focus that much on a complex approach. There is so much you can do through retrosigmoid craniotomy. Something that I have gone through my career, by the way, when I was, you know, I did a fellowship with Alan Efdi, and was enamored by petrosectomies radical skull-based osteotomies. That was maybe the first five to 10 years of my career. After that I went through a couple years of transition and now I just have learned that as you get better, you can do so much more through smaller exposures. In fact, the dynamic retraction, that experience of seeing the 3D anatomy through your brain and appreciating without having it all exposed in front of you are values that take time. So when I talked to Bill Caldwell, I think both of us believed in the same idea that as we become more and more advanced, mature and experienced, we find that we are less relying on the osteotomies and skull-based approaches such as petrosectomy and we're able to use the retrosigmoid approach, transtentorial approaches, suprameatal approaches, maybe a far lateral approach and be able to remove the tumor effectively. As you know, the petrosectomy it takes a sizable portion of the day, especially if your ENT colleague likes to take his or her time to do the procedure, it may be one or two o'clock when you're getting to the critical part of the operation, and that can be a real challenge. And I think that's something that I have learned as I've gone forward. Do you feel the same way or how do you feel differently about that?

- I do feel exactly the same. And I think you and I went through the same evolution process and my talk even echoing that by finishing with a retrosigmoid and showing that not everything you have to do through Kawase, that you can do retrosigmoid, suprameatal, infratentorial. That last case also confirms what you're saying, that extensive tumor that was going all the way anterior and posterior, I had two ontologists that I work with an alternative on doing the total petrosectomy. And one day then we closed and the following day I came and I started resecting the tumor fresh in the morning. I don't remember the last time I stayed past 5:00 PM in the OR doing one of these cases. And I totally agree with you, as you become more experienced, more aware of how much we hurt people in the past doing this heroic procedures, staying all day and night, nothing good came out of that. And we reverted back to staging or even staging exposure and resection. And again, you know, I mean, when I expanded that algorithm including retrosigmoid, don't forget that retrosigmoid is the workhorse for the posterior fossa. So I totally agree with you. I mean you're an experienced surgeon obviously, and you went through that evolution that we're at the same conclusion.

- Yeah, thank you. And I do believe something very well you mentioned that's the time of the day when you do the surgery. I also close, I mean, we are going home at five or 6:00 PM if we're doing the whole case the whole day.

- Yep.

- I think for petrosectomies it's ideal to do the exposure one day, resection the other day. If you wanna start doing, you know, resecting tumor at 3:00 PM and it's 10:00 PM and you are really getting to the critical part of the operation, that's a big mistake. It's something neurosurgeons again don't appreciate and that's fatigue. And that's really the time when you get to those critical part of the operation in these cases when it's 10 or 11 o'clock at night, you're just not yourself. You don't know it.

- Exactly.

- It's sort of self-awareness is no longer there. So it doesn't matter what case, it doesn't matter. Obviously patient has to be stable, you can't close in the middle of bleeding. But if everything is going okay and you feel like it's six o'clock, you've been engaged with this for a while this afternoon, it's best to close, come back next day. Don't try to prove yourself. I think that's really a rabbit hole and it's a recipe for trouble. Don't you agree?

- I do agree. And modern is the key word. So we call this modern skull-based surgery or contemporary skull-based surgery where you exactly think the same way. Can I do this through a staged approach? This is a huge tumor. Instead of staying all day and night doing this, you know, why don't you do it two separate days? There is not no, no shame on that, you know. I mean there is no problem doing this, you know. And having a team that's, that's a great secret to skull-based surgery. Fellows, the fellows are really the lifeblood of our practice that, you know, when you're tired after intense like dissection of cranial nerves, basilar artery perforators, and you don't wanna cut corners when you close. So you alternate with the fellow on the case, for example, of the neurosurgical part. And when it comes to closure, they're more fresh, they're younger, they're more, I would say perseverent in closing and meticulous, putting things back together. Closure is like really, really a huge part of what we do. Without good closure, patient will come back with problems, either CSF leak or infection or, so that's another secret to what we do, teamwork.

- Yeah, it's a team sport. There is no question about it. And nothing, you know, you can do a great case, it goes beautiful and they come with a leak and meningitis and that really ruins it. Really ruins it.

- And ruins you on the next case because you're about to start another case and the patient comes in the morning to the ER and you get the bad news.

- I know, I know. Attention to detail to the last stitch.

- Right.

- And also something you very well mentioned, these nerves and arteries, life runs through them. These perforators are truly the lifesaving of a patient. And so you've got to have a lot of respect for them. This idea of I'm a skull-based surgeon, I can do anything, especially in the younger people who wanna prove themselves, they're better than the experienced surgeons. I have to tell you that there's just, there is no way, these things are so unforgiving, these perforators, these nerves.

- Right.

- The vascularity to them. It's not just the anatomical preservation of the nerve, it's the vascularity to them.

- Function.

- Yep, to keep function. And it's so important to do a subtotal resection and save the patient. Please, please, please. I mean it's so clearly the right route. When there is any question, leave some tumor. You can always come back later. But don't try to push your limits to prove something. Because at the end of the day, it's not us on the table, it's someone else who's trusting our hands. And every cranial nerve has a lot of life in it. A lot of life.

- Right. A lot of future. And most of these tumors are benign. So don't be heroic. Please think about what would you do if it were you on the table and plan accordingly. And I'm sure you have done that. I can see from your technique, really that meticulous technique, sharp dissection, not pulling on things that you beautifully demonstrated, Samy. And always remembering that don't focus on the exposure. In other words, don't worry too much about how you're gonna get there, worry more about what to do when you are there. I think that's really the final determining factor about the outcome of the patient. Do you have any other lessons you wanna share with us in many years of your complex skull-based surgery, Samy?

- You know, I always say when we show these videos, we don't show like a heroic procedure saying that, you know, I'm in a different place than you, no. I'm in a different stage than our young learners. We share with you, with our young learners that we always started where you are now, and we're here because we learned from our mistakes. We practiced in the cadaver lab. This is my secret, the cadaver lab, learning anatomy, watching videos like your Atlas. It's a great venue for that. Learning, learning, watching, practicing and building more experience. And you'll get to be at that level one day. So it's not like we're born experienced neurosurgeons. No, we learned with time and from error and trial. And I like to share that with my fellows. And I say, you know, with the residents and the fellows, what we learned the hard way, I'm trying to share with you in an easier way, but you're also gonna learn from your own experience and your own cases. So when you think that you stop learning, then you stop practicing, because it's a lifelong learning, skull-based.

- Well said. Very well said. When you don't think you need to learn anymore, you need to stop practicing. Beautiful job, Samy. Very proud, really enjoyed it. Thank you for being so kind to us and I look forward to inviting you again.

- Well thank you for the kind invitation. And again, you know, your contribution to the field is just priceless, okay.

- Thank you. And this Atlas that everybody use as a learning tool is a great contribution and we're really proud of what you contributed to the field, Aaron.

- Thank you.

- Of course, I'm proud of our friendship. That's another personal thing.

- Of course, of course. Same here. Thank you Samy. God bless you.

- Welcome. Thank you so much.

- Thank you.

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