 The main idea is, it is not only intraderial and extraderial, you have to actually define whether you want to take the complete clinoid out or the partial clinoid out. The partial clinoid is the one which is the medial part of the clinoid and the upper part of the optic nerve. That is actually the one to be used for clinoidal aneurysms which are small or medium in size because that is where the neck would be. For giant aneurysms, the pereclinoidal carotid cave because then the definition of thymic becomes very, very ill-defined or they are going to the cavernous sinus, we want that exploration plus giant aneurysms have that thing that you need space to apply the clips and you have to be parallel to the internal carotid artery. For that, you need a complete clinoidectomy. So that is where the concept came in that complete clinoidectomy cannot be done intraderial or extraderial. So the main idea for intraderial was that you always have a control over the IC. You do not actually injure the IC but you can injure the aneurysm initially. The thing is when if you see extraderial, extraderial is probably more safer but yes, it requires a lot of practice. It requires some decisions on the endeavor because you actually have to imagine that your clinoid process is like this. The main idea if you see it extraderally and I will show you here, this is the frontal dura. This is the temporal dura. This is the orbital lateral wall, superior orbital fissure. This is the clinoid process. What you are seeing is this only. So if you start drilling it here, this is v2. This will be v superior orbital fissure. If you just expose a bit of it and you start drilling it here, you will be actually, you will keep on drilling inside, inside, inside. You are actually drilling into a cylinder. Actually it is like a funnel and after some time you stop because you do not know where you are reaching and they can be injuries and why aneurysm because your aneurysm will be here, your thirdner will be here and the IC would be under this. So actually you are drilling this cylinder from base of cylinder. One of the people who actually invented the extradal anatomy, they said that this cylinder is actually just a base of a pyramid. So that is the lateral wall of the orbit that you had. This you can do it without orbiters, I do it many times. So that is v2. So this is the tentorial duplicature that is also known as the meningo orbital band which is always there over this clinoid and it extends right down. So what you are doing is rather than seeing this, you are taking off the dura above this tentorial duplicature. This cannot be done from a keyhole approach. You need, you need an angle of approach and so that is v2, that is v1, v3. So you just need a small clinole craniotomy. May or may not have an orbital diagrammatic. This is an extra exposure, we do not need that much. So now you see this thing which was hidden has actually become like a pyramid. So this pyramid, we take this off and this part of the thing, you are actually drilling on the lateral wall of the pyramid rather than on the ring of the pyramid. So all the time you are actually drilling at the lateral wall. So the ICA would be here, this would be the optic nerve. All the aneurysm and all will be actually coming here. So you are actually towards the third nerve more. So while seeing this pyramid, you must see the tip of the clinoid process. Why this is important and why this can more be done extradurally than, than not intradurally that is complete clinole craniotomy because in 1% of cases there will be something known as the middle clinoid process, a bony process between the anterior clinoid process and the posterior clinoid process. So then your anterior clinoid process actually does not move, that is a giant thalmic and you do not know where the neck is, it is a broad neck, you can just see the thalmic. So that is the tendonal duplicature, the orbit, that is the, I think the frontal dora, the temporal dora, yeah that is the, so this, that was the clinoid process, you are actually making the clinoid process into a pyramid, you are actually seeing the whole length of the pyramid, peel it down, that was less peeling. See the optic nerve and that will be the carotid artery in the allent triangle and that is the shell of the bone, you must dissect it, make it into a shell, deliver it out like a, like a do a tooth extraction, that always bleeds, that is the cavernous signs bleeding. That is another reason why a complete clinoidectomy can be more safely performed in an extradural approach because there is always some ugly bleeding from the cavernous sign which you can put some fibrolar, surgery cell, then you cut the dora as a T like this and you cut it like this. So actually directly cutting it over, you have seen the aneurysm, that is the optic nerve, that is the giant aneurysm, yes but you are drilling like a cylinder you will definitely hit this, that is the ICA A1, you are putting a temporary clip on the A1 and that was the peak com sorry, coagulate the aneurysm, never clip these aneurysms directly, always coagulate them, make them smaller, define the neck by mobilizing the optic nerve and here I must tell you that you must decompress the aneurysm before you actually clip them because they may be thrombose, you may have to decompress, you must have an MRI in these aneurysms to define if you have a partially thrombose which must be removed, the aneurysm must be done before you apply and this is something like the curtain, you can see the curtain nicely but the moment it crumples, it is just like this, you cannot put it in one clip, you will be requiring several clips like a tandem to clip them and then this is actually clipped, just another video, so here you cannot actually define the neck, where the neck is and that is the other side, this is the frontal temporal and this is the cylinder of the ACP, you are actually taking it into a wall of a pyramid, your drilling should not be like this, your drilling has to be like a paint brush or drillings have to be paint brush, especially the deep drillings over the cortical bone, either you are drilling on the clinoid or the internal artery canal or the odontoid process, right down the duplicature has to be cut till the tip of the clinoid, when you have seen the tip of the clinoid, you are actually feeling it, you know there is no bony process which is coming, then you drill it like a paint brush, what you are drilling is, you are actually drilling it and over the ACP and over the internal cortical artery and the optic nerve, initially with the cutting and then you can use the diamond, make it into a shell, once the moment the optic strut breaks, this actually can be delivered, if it cannot be delivered that means there is a middle clinoid process, then do not struggle, but you can see a middle clinoid process on your CT scans, that will be the optic nerve, then the last part you must dissect the dura around and deliver it, never try to yank it out or then the temporal dura, the that is the T, the V and then the T, the T is important because you can actually put your clips like this, otherwise all your clips have to come like this, that is the aneurysm state, it is practically there is no, there will not be any retraction, the cutting of the dura has to be between the optic nerve and the carotid artery, that is the groove that you have to cut there, that is the safest, preserving the thalmic, then defining the neck, that is the A1 MCA that was completely adherent, there is a neck here, you have to define a neck on that side, now we still have some more bone over the optic nerve to take off, because the optic nerve is actually has an acute angulation, this patient was blind but still it is better to have saved the optic nerve, then again the same thing vagulation and decompression, that is the optic nerve and here I had something wrong, there was a rupture there, that is the optic nerve and I was dissecting, so that is an accident rupture which can happen in giant aneurysms, can be actually bad because despite all the temporary clips, it is still bleeding, mostly because of the thalmic, this is another reason why an obidizagumatic and extracellular drilling will actually give you slightly more space there, but here you must preserve the, what will come here, structure which you have to preserve, what I am trying to see, thalmic is here, no that is there, that is the IC and that is the pituitary stalk, you have to see the pituitary stalk, you can see that, that is the pituitary stalk, you should not take care of the pituitary stalk in your clips.