 If you see this video output you will realize you will see that this is superior, this is inferior, this is one side and this is the posterior fossa, this is the middle fossa. This is the bridge of bone that is the pitris bone separating the posterior fossa from the middle fossa. If you see the occipital side, you will see the internal auditory canal. Then medial to the internal auditory canal and this ridge, on the upper side you can see the foremen lacerum here, that is the foremen lacerum, that is the foremen spinosum and that is the foremen lacerum, this one slightly more up, this one. That is the foremen spinosum, foremen ovale, foremen lacerum. Anything above the foremen lacerum and medial to the internal auditory canal, that is the dense bone which is devoid of any vessels or nerves, that is the pitris epics. It is under the impression of the Michael's cave. So we will come to that. So this is what we will be talking about. This is the more important part, the central scullways. We already talked about the anterior cliente process, the superior orbital fissure, the orbital apex, that is the cavernous sinus, that is the posterior clientoid and the pitris epics. You may not be a scullways surgeon dealing with these pathologies but this is one place which will, every micro neurosurgeon or endoscopic neurosurgeon will be dealing this with this area sometime or the other and it is very important to know the anatomy of this place. These are my teachers. So this is what we will be talking about. This is bounded by the GSPN, the arcuate eminence, the V3 and the pitris ridge. It is behind the gasoline ganglion, we lateral to the superior pitrious sinus and anterior to the arcuate eminence and medial to the GSPN. So you can have an original triangle which can be opened like that that I will show you. So I will just come on to the real skill stuff, we will not talk about theory here. So what you should do is a simple temporal incision. Once you have given a simple temporal incision, you can either do an osteoplastic flap or a free bone flap. Here I will demonstrate a free bone flap and most of the artwork is osteoplastic because then you do not have to, really if you do not have any place you do not have to fix them back. The temporal cuff stick is left behind, the temporalis muscle is elevated. Before that incision of the temporalis over the temporalis fascia is important. So that you save the facial nerve. That is from the line joining the kibar hole to the root of zygoma. So it will be somewhere here. So that is where you must incise the temporal fascia before you elevate the skin flap down. But if you have already elevated the skin flap down and then you incise that means your facial nerve is already stretched too far. That is something that you can do. Take this. After that expose the zygomatic osteotomy, the zygomatic bone. If you are planning a zygomatic osteotomy, for a standard posterior clinoid lesion or for a petroclival meningioma or a trigeminal shonoma or a basilar aneurysm, the spectrum of lesions just need to do a zygomatic osteotomy. If the lesion is extending into the anterior cavernous sinus, superior orbital fissure, then you have to do an orbital zygomatic osteotomy. The small standard temporal craniotomy or a terional craniotomy is enough, followed by a zygomatic osteotomy or an orbital zygomatic osteotomy. So just showing you the difference between the two, what exactly is the difference. Here when you are doing a zygomatic osteotomy, you are actually dealing with the lesions here. The rotation becomes much more. So you are actually having more rotation of the head to the opposite side because your focus is towards the posterior aspect. Your craniotomy goes a bit more back, less terional. This is the standard terional craniotomy. And your cuts can be, have to be in your, its centering is at the spinoidal ridge of the terion. Here the centering is usually at the formino valley, between the formino valley and the formino tandem. So it is basically, this is the centering. How do you localize the root of zygoma when you are, how do you localize this formino spinosome? When you have done this craniotomy, the root of zygoma, if you just see the root of zygoma, 2 centimeters under, just deep to it, is always the formino spinosome. So if you have, if you have an extradural hematoma with a very swirl bleeding and there is a lot of gush from the temporal aspect and you know this middlemen angelotomy and you cannot find it. The best way to find it is just palpate the root of this zygomatic process. Just 2 centimeters under that and that we will find in the middlemen angelotomy. Once you have done an orbital zygomatic osteotomy, when you elevate that free bone flap, there always a buckle pad of fat under this bone. Once you remove this bone, you can take out some, some zygomatic pad of fat, which you can replace either when you are taking off the clinoid process or your vitreous bone. Even if it is clear and there is no pneumatization of any clinoid or any vitreous, it is always better to have this, this pad is, this zygomatic pad is given free for you. Just take it and put it there. Even if you do not want to do, use some glue, it will help you, at least a psychological leaf will be there. Then reduce the sphenoid range, which I showed last time. From the sphenoid range, first step, then division of the middlemen angelotomy, dilation of the formant spinosome, lateral wall of the cavernous sinus, it should be dissected, V3, V2, anterior cavernous sinus may not, you do not require, the main process is only this. This is the area. Why you have to strip the posterior cavernous sinus or expose? Because if you only do this till here, you can see there is a very small approach. This is just small oval or a triangle type of thing behind the GSP and that is the blush of the ICA, that is the Meckles cave and that is the archway terminus. So, you only have a small pace here. But the moment you open the, the dura till here, you have a big void here and you can actually drill everything right to the base, where sixth nerve actually goes out from here under this. Then drilling of the Petrus apex, Glasgow Crock triangle we never expose, opening the middle fossa and the posterior fossa dura, sectioning of the tentorium and intradural posterior fossa can be seen. So, this is what the standard incision, the hydration is should be much more to the opposite, it should be on 60 degrees. Standard small temporal incision has to go down the daigoma because this is where the zygomatic process is and you have to remove that. The temporal crinotomy and the zygomatic osteotomy, we usually do it osteoplastic, it is simpler to close. This can be done in pitroclival meningiomas because you can go straight in and remove these, when they are larger, you cannot remove by the straight approach, you need a retro sigmoid approach along with this approach, a combined approach. I have stopped doing complete pitrocel approaches now, so a combined approach here will become an anterior peterous with retro sigmoid. Retro sigmoid is a very important approach, with a standard retro sigmoid you cannot reach this area, so this will help you to reach that part of area. This is a type of, that is pitroclival meningioma with the old video. Foreman's pinosum is drilled, middle meningiol artery is exposed. Then same meningiol layer is separated from the membranous layer, the section over the V3, V2 complex, on the back towards the pitrocepex, here will be the Gspn. There is always some oozing there because of the vascular channels, and this had a meningioma and always more vascularity. This is the area which is important to be drilled. This is the arcuate eminence, the V3 Gspn and the pitros ridge. Always some bleeding from the cavernous sinus from the Parkinson's triangle area. Drilling it down to the posterior fossa dura, open the middle posterior fossa dura, open the middle fossa dura. So it's a standard temporal in duotomy, just at the base of the temporal, you actually open the duotomy, the temporal duora somewhere here. Then putting a linear down till the middle fossa, that's a tentorium. By doing this approach your tumor is already de-vascularized here. That's the fourth nerve. That's the centorial section just behind the fourth nerve. But this involves the superior pitrosil sinus as well. That's the posterior fossa dura. So by this approach what you have done is, you've done, combined a sub-temporal approach with a pre, I would say a pre-clival approach, upper-clives. So you've opened the posterior fossa and the middle fossa into one compartment. I feel it's a very nice approach and a very safe approach. The problems are not in the approach. The problems are actually when you, it's the inside where, which will be there because of the problems of these tumors itself. These tumors are very adherent to the pia and to the bacillus perforators and they take a long microsurgical time to dissect these. Therefore, I'm actually worried when people talk about endoscopic removal of pitroclival meningemus because even microsurgical position with 15 times magnification is very difficult to separate these perforators and you have to take, take a decision in 10 to 15 percent of times or maybe sometimes 20 percent of times, leave a bit of tumor over that area. With the complications in these surgeries, if you have a lot of perforator handling or damage, it can be absolutely not rewarding at all. It can be, it has a fifth nerve, tumor is removed. We don't do any basilar bifurcation aneurysms. Pustier circulation is hardly clipped now. Yes, these are rare clippings which I do maybe once in the six months or so because they fail and when they fail, they, they come to us. So this is field embolization at two centers because broad base, very thin PCAs, they couldn't put stents. So that was a slightly low lying basilar aneurysm. So same middle meningel artery, that's the V3, same petrus, apex is being drilled. Now the tumor is opened behind the fourth nerve. So with this approach, you are open to Pustier fossa as well as now the middle fossa. That's the fourth nerve. You're dividing the tentorium like you usually divide in a sub temporal approach. The only thing in, in the sub temporal approach, you cannot go beyond one centimeter because the venous bleeding will be there. Here, you are actually coagulating the superior petrosil sinus and you can go right through the Pustier fossa dura. And when you open this, the basilar artery will be here somewhere and that's the fourth nerve. Fourth nerve is something that can be mobilized by three to four millimeters along with its neural sleeve. That's the third nerve. Third nerve cannot be manipulated unless there is something known as an oculomotor trigone. If you open it to oculomotor trigone, that's an eight to 10 millimeter. That in any sub temporal approach, like please don't try to manipulate the third nerve. It's very, very sensitive to any manipulation. But if you open the tentorium over the third nerve, you can manipulate it by at least five to eight millimeters. So that's the basilar trunk between the fourth and the third nerve. Putting a temporary clip here, we dissected the PCS. The PCS were incorporated, tilted a bit. So the temporary clip is on, then we coagulate. That's a temporary clip. The temporary, the, the aneurysm is coagulated. You cannot clip these aneurysms, these broad neck aneurysms here with one go. You have to reconstruct anywhere. That's the thing with aneurysms, that if you want to reconstruct, make them into a smaller neck, a nice circular neck. And that you can do easily with some coagulation under, under water, then you can clip it, clip them. That's the opposite third, the PCS. Basilar aneurysms and ICA bifurcation aneurysms. Our two aneurysms, if they are broad neck, the fundus is nearly the same as the neck. Size, the ratio. If you have put a clip and you are sure about the perforators, please don't rupture and try to prove to yourself that you have completely clipped aneurysm. Your clip will just blow out. These are two areas where if you want to rupture, you have to put two clips. If you really want to, two or three clips and then you rupture. Because in one clip will be too light for that jet of an ICA bifurcation or a basilar bifurcation, just blow out. Because I've burnt my finger once, I can tell you. So that's a fifth nerve sonoma. So if we can, we can take off this small Petrus apex. Fifth nerve sonomas usually amputate the Petrus apex. And this, you have to drill a bit more and then the tumor can be removed. Another fifth nerve sonoma, where this part of the Petrus apex, you can direct, these are tumors you cannot access with any single approach. You need either a middle fossa or a posterior fossa, but this extended middle fossa can help you deal with both things. So the same. These are actually inter-dual tumors. These are between the meningeal layer and this and the membranous layer. So you open the two layers of the cavernous sinus. That's the tumor. Along with the third V3 and the V4 and the V2, that's the Petrus apex. These tumors should always be approached extradurally from the middle fossa. You should never approach them intradurally. You will damage the nerves. Then a bit of Petrus apex have to be removed. Whenever I was training with Dr. Vinko, Dolan C always used to say that if your fifth nerve sonoma, if you reject a fifth nerve sonoma and the patient does not improve sensation, all the sensations do not remain the same. That means you've not done good surgery. That means you've damaged the fascicles which were from the which the tumor was not arising from. So once we have taken this out, then we can... So once this posterior fossa is also there and you can see the tumor is now coming like this, then it's all sharp dissection. Fifth nerve sonomas are very bad. They're just like NF2 bilateral acoustics in which the problem is they're not crucible. Even if you have the highest power, it just is there. It doesn't move. The user doesn't move. And loop cotter is not safe here. My angioma is alright, but loop cotter is not safe for this. The best way, the safest, they bleed very less. The best way is to just take them with knife with small, small bits and keep on doing some sharp dissection at the surface with. So when you're cutting with the front of the knife or the blade of the knife, but you're dissecting with the back of the knife. So that movement you can practice. And you must try to identify the fascicle from which the tumor is arising from. Yeah, that is the fascicle. So there's only one or two fascicles from which this. And we must divide that fascicle to remove the tumor. The rest of the nerves should be absolutely preserved. That is one hallmark of pitrochloroma angioma. This approach is very versatile. I have used it in everything practically. They've done bilateral histocytosis. This is published by, I think Deepak had published it. Pitrochloroals, condosarcomas, we get huge tumors. So this was removed from this approach as such. Cordomas, but another problem with cordomas is, now I feel, I still feel that cordomas of this type, they're not extradural. They become intradural. I'm despite being doing a lot of, after having interacted with my German friends, doing a lot of endoscopic work, all my pituitaries are in copy. But whenever there's something intradural, I feel afraid. I'm more afraid about the CSF leak. These tumors I'll still do anterior transpetrus and cover this with nice whatever I cannot remove in front. I just cover it, seal it from inside with a dual patch, going after three months. In this, I've been three months. At that time, it was microscopic. So I took this out of the microscope. That was fine. Then a very super giant ones, which here is a frontotemporal craniotomy with this. And surprisingly, when we mobilized this and took the solid part out, the rest just came out. It was just carbonate and just kept on coming out. And the ones which were going into posterior fossa, craniopharyngeumas, epidermoids going everywhere. So advantages is, what does all these approaches help you? It convexitizes the deep seated lesion. The most important thing is, it gives a brain protection and a venous protection, especially an extradural approach. If you do these same approaches, if you do a petrochloric meningioma or a simple tentative meningioma, which is going to posterior fossa just by sub temporal approach, by any intradural approach, you'll damage the vein of labia. If this is one approach, where the dura is always covering the vein of labia and you are doing a sub temporal approach without even doing anything to the vein of labia. So it has advantages, it's a big area for drilling. If you're drilling straight at the peterous apex, you need some practice for that. And you have a direct access on the metal scave and the fifth nerve and the duralis canal. Sixth nerve is most important. In all these fifth nerve sonomas and meningiomas, sixth nerve is something that can be injured. You're avoiding a complete peterous approach and then you have to be very slightly delicate to the geniculate anglion. The only disadvantage is posterior cavernous sinus dissection that you can learn with time. For any skills program, this is a skills and you realize that when we talk about skills, we don't only talk about that you take an endoscope and go in or you take a microscope and take a drill going. It's very important to learn the anatomy. Anatomy is very, very important. So you need neuron anatomy. For any skills training, neuron anatomy is something that comes first. Tissue handling is very important that you can learn by knowing your instruments. Microsurgical skills, the two most important microsurgical skills. One is arachnoid handling that you can only do with good microscopic practice, which we realize that high zoom micro switching practice makes you learn a lot. Then high speed drilling, that is something which is very important. So thank you, thank you very much.