 So, you see anti-clinoid drilling is required in two situations. One is for tumors, tumors which are maybe tuberculums, saline, meningiomas or most often tumors in this area which we call paraclinoid and going into the optic foramen. So, lesions which are in this paraclinoid or paraclin area or tuberculums, saline, meningiomas or cavernous sinus meningiomas and going into the optic foramen, they will require drilling in this area. And for tumors I always prefer to do extra dual drilling because of two reasons. One is it is safe and you can de-vascularize the tumor and many of the times this is associated with hyperastasis. So, for tumors I prefer to do always extra dual drilling to get rid of this hyperastatic bone and to de-vascularize the tumor before I drill it and get more space and re-roof the optic now. For aneurysms I always do inter-drill drill because I want to see the aneurysm before I drill it. It has happened once or twice that while the extra dual remain although it is not that common sometimes aneurysm can rupture if you are not so careful. So, for aneurysms I would suggest you do under vision drilling inter-drill and for tumors you do an extra dual drilling and this is the basic principle I have followed. So when we have to do anti-clinot drilling the first step is of course a frontotemporal kinautomy or a terional kinautomy and taking off the swineidritch. So once you have done a terional kinautomy you take out the swineid, lessening a swineid. This is lessening a swineid as all of you do and open up the spare orbital fissure. Once you have done that then we start drilling the terional kinaut. The basic step is you core out the bone till you get a thin shell and then you remove it either with a desector or with a needle holder. This is the basic concept. So it is very simple. Cleanoid has two roots. One is towards the tuberculum cell area or the planus and second is the optic set. So you core it out and in tumors you have to decompress the optic nerve in the area because most often the tumors in this area even if you see it or not it is going into optic ferrament. So you have to decompress the optic nerve. So this is the cleanoid process. This is the one which is going towards the planum and there is an optic set here which is seen here. I will show you different ways. I mean this is the optic set. Keep other cleanoid. The lesser wing coming here, superior orbital fissure, lesser wing. This is also sometimes called one root of the cleanoid process. So some people say it has three roots. One is the one which is towards the lesser wing of the swineid. Other one is which is below this and middle to this is the optic set and the other root is like this. So when we are coming from this side, terional side, we are removing the bone. There is a vessel here, orbital vessel which you coagulate. Remove this bone here by a standard drill and then start drilling out the cleanoid process here. So lesser wing of swineid, optic canal, anti-cleanoid process, optic set. Sometimes you have a middle cleanoid process here. Yeah, this is the middle cleanoid process here. The lesser wing of swineid, optic canal, anti-cleanoid process and sometimes you can have inter-cleanoid bridges. Just various diagrams showing the anti-cleanoid process. Sometimes it is pneumatized. That makes your law very little easier and sometimes this can extend into the swineid sinus also. So you have to be careful sometimes when you are drilling, you can open the swineid sinus. No, it is nothing major but you have to know about it. Otherwise you can have a C-safronoria unless you really pack it. So you have to know that this can be pneumatized and this pneumatization can extend to the swineid sinus. This is showing the pneumatization. This is not a sign that this is optic cleanoid process which is pneumatized. So this is a standard diagram from the rotons. You cannot get better diagrams than you get in a roton. So there is no use getting or replicating it. Just take it from that book. So from the anti-cleanoid process, when you talk about dural folds, there are two duals, upper dural ring and lower dural ring. Dural from the upper surface of the cleanoid process leads to the upper dural ring and from the lower surface of the dural dural ring. And in between these two rings, so many names are given. The cleanoidal segment of the cavity dart, you have the cavity cave. So this is an important information you should have. And when you are doing aneurysms, especially character of thymic aneurysms, you have to open the upper dural ring. So you follow this. Normally there is a falsiform ligament which extends from the anti-cleanoid process to the optic nerve. So once you cut this thing, before you start drilling, you must always cut this falsiform ligament. Because quite often when you are operating on pica martyrian rhythm and you see, you feel that you don't have a proximal control, you just cut this falsiform ligament. You get a little bit mobility of the optic nerve and you can see the proximal neck of the aneurysm, especially in pica martyrian and sometimes character of thymic also. So you need not drill that time. So before you start drilling anti-cleanoid, you cut the falsiform ligament, try to mobilize the optic nerve and see whether you can get to the proximal part of the aneurysm. You get my point? So then even after that, you see that it's not okay. Then you can start drilling. So aneurysms, that's why there's another reason for doing intradural drilling for aneurysms. So because you have to mobilize the optic nerve and then start drilling if required. So just going through the upper ring from the upper surface of the clenoid, lower ring from the lower surface of the clenoid. And in between, this is the segment that is the clenoidal segment. This is the lateral view. Optic nerve, cavity artery, clenoid process, dura from the upper side forming the upper ring from the lower surface forming the lower ring. This is the carotid artery forming a loop here. This is the clenoidal segment dura. So you have to cut this ring to get to the aneurysms proximal leg. This is an important step. And this is easy. It may sound that is something difficult, but it's very easy. I mean, this is a tough dura. You cut it with a sharp scissors and it's somewhere, only if you cut only one or two millimeters, you have a remarkable amount of space you get to proximal to the aneurysm. So just the same thing. So this, I mean, I'm just giving you again and again the same so that you have visual impression of what you're doing. It may sound repetition, but that's all. Same thing. The carotid artery, once you see the optic nerve, you see normally when you're doing for clenoidal carotomy, the carotid artery you see lateral to the optic nerve. But you must realize below the optic nerve, it is just below and coming from the middle side. So it is not always lateral because it is coming from the carotid segment of the carotid. And when it's taking a loop, it is below the optic nerve and then coming lateral. So this must be clean in your mind. So this is the first step is clenoidal carotomy. Second step is taking out the lesser wing of suenoid. And third step is anti-cleanard process sticking out. Ultimately, when you have practiced all the approaches, you come down to only three things. That's why I'm concerned. One is you must know how to do anti-cleanard drilling. Second thing, you must know how to do a good retro sigmoid exposure. And third thing, you must know how to do a frontal orbital diagramatic. Other than this, practically you don't need to know any other skull-based approach. This trans-pitrocell approaches anti-pitrocectomy still has a role, but posterior-pitrocectomy, complete-pitrocectomy, extreme trans-controller, they are all overrated and not really required in more than 95% of cases. So basic frontal orbital diagramatic or a standard clenoidal carotomy, anti-cleanard drilling, and a good retro sigmoid approach is one which will take through all the clinical situations you will see in your life, in 99% of cases. Take it from me because I have done all this. I mean, I may be wrong, but this is what I feel like. We have done all those approaches that come down to these only. I'm not doing any other approach now. This, I don't have a CT of the patient which I am doing this. This patient had a planum tuberculum saline meningioma extending into the orbit in the optic carol. So I thought that we have to drill the clenoid and de-roof the optic nerve also. So we have taken out the lesser wing of senoid and this bone was hyperastotic. We will keep on coring it. Just core it, core it, make it thin and then remove the shell. So this is taking longer because this is a hyperastotic bone. There was a meningioma, it was a hyperastotic. Extradural drilling advantages, you can use a detractors and be safe and don't keep any cotonide or software or anything. Keep the clean area free. Just keep on doing it. And keep on having a look in between whether this is becoming free or not. After some time, this will become a free and you can mobilize and just break it like this. So you see, this is becoming, you are making a bigger hole. You have to core into the clenoid whether you make on increasing the hole from inside and try to, in between, these are being reflected here and trying to see it is not still free. It is starting to move a little bit. You see, this is important because you must know when you're coring. I don't want or you should not want to go across through and through and then see, okay, I've done. In between stop and see how much outside the bone is still remaining. Then you can keep on breaking it. In this patient, I had to de-roof the optic nerve also so I had to remove the strut also. And this is a fine nibbler, sometimes a needle holder can act as a good nibbler. Now this is the left side because the optic nerve will come somewhere here. So this is still a huge amount of, these are the large hypersources. So you have to still, this coring has to be done further. And when you're using a drill, always use, don't do half hearted pressing over the, just press it fully. When you have to take it out, stop it completely before you take it out. Don't start pushing the foot pedal till you are on to the area where you want to drill. And these may be small things, but I have made mistakes. You take the drill and put the pedal here and while you're coming, you injure something on the way. So first let the burr come into the view of your microscope and at the area where you want to drill before you start pressing over the foot pedal. And press it fully. This side dura is quite free now. Yeah, now you see here, probably we have gone through and area. Now this side will be the optic strut. You see here, this dura has come here. This is probably overlying the optic nerve area. So this bone is the optic strut. And this is the area of the other root which is going towards the plenum sonoidal. And in between sometimes you can use a one mm kerosene also to remove the bone. One mm kerosene is a very good instrument. Because sometimes you get tired of doing the diamond drill, maybe taking too much of time. So this is a helpful instrument. Can you see this thing here? Probably once we remove this, this is the area where the optic nerve should be. This is the optic strut. This is the area where the optic nerve is getting deroofed here. There's still a bar of bone here. Once we remove this and then take it over. So we have to. Can you appreciate this optic nerve area here? This is the X-ray dual optic nerve getting deroofed. I'm using AM8, AM8. Diamond drill takes too much of time. So I'm just showing you this thing so that you have to, this is an important step in these tumors. Even if you don't remove, not able to remove the tumor completely, you have to deroof the optic nerve. That's the most important thing. That's what I'm showing. This is optic nerve almost completely deroofed except for this part now. So this is the optic strut area. This is towards the plenum sonoidal area. This is the optic nerve and we have completely deroofed it and removed the bone over it. So just spend some 10, 15 minutes here. So this will be helpful because it will be deroofing the optic nerve and it will be de-vesperizing the tumor. In this patient, when I opened the dura, it was practically like a vesperotumor because we had removed the bone, we have coagulated the dura and practically for patient point of view, we had done the optic nerve decompression and then this tumor was a cavernous senus meningoma. So I left part of the tumor and I did not enter into the cavernous senus at all. Just remove the tumor which was outside and then gamma knife. I have become conservative with this. So I just, so this is the optic nerve completely deroofed and this is the last part of the clenoid process which will be removing here. So this is, we are at the anterior edge of the thing now. So this is the last part of the clenoid process which is being removed and completely deroofed. I think we'll stop here.