 What I will do first is, let me just point out some of the important things that we do at surgery when you want to mark a flap. The scalp flap in general, we try and make it cosmetically acceptable. So, you do not want to get it on to the forehead and stay behind the hairline and you keep the base of the flap broader than what the length is going to be for the vascularity. And if you know all the vessels that come in from the base, you base your flap onto one of those vessels, all right. Now, in terms of marking the flap based on the MRI showing you the lesion, there are some bony landmarks which sometimes we find confusing. So, let us just go through them one by one. The sagittal, the midline, quite often you find that once you position the head and somebody tilts the head a little bit, the other person comes and marks it completely off the midline. So, please take a pen, feel the lesion and mark it along the midline. And so, you are absolutely sure that you are on the midline. So, midline is one thing that is extremely important. I assume that all of you practice the timeout. Do you have a timeout? You know what a timeout in basketball is. You have everybody sitting and playing and then suddenly the coach notices that there is something going wrong. He calls it a timeout. He gets everybody together and they stop what they are doing and they discuss what the problem is and then they go back in and fix it. So, at surgery when you are doing before you start, the anesthetists are busy starting the lines. Nurses are getting the equipment together. The surgeons are putting up the scans. And so finally, nobody knows whether you are operating on the right patient. Are you doing the right side and what procedure, all right. And so, I have a notice in my theatre saying please practice the three P's. Patient position and in Tamil, side is pakam, so, patient position pakam. Make sure that you do these three things. So, side is important, all right. It seems silly, but please do it. I have seen one situation in our theatre where a senior professor showed the, on the left of patients, the head is fixed. He showed the junior consultant, he marked the coronal and because he marked the coronal on the left side, the consultant thought that that was the side that he wanted to operate and they opened that side, okay. So, the person who is going to be marking the flap, please make sure that you do these the timeout. Now, and that is why the midline is going to be important. And then you have to say, this is a left-sided tumor, this is the left side. Sometimes when you turn the patient prone, you are going to get your side mixed up. So, it is not silly. Next is the coronal suture. Now, where would you look for the coronal suture, feeling for it? Because you cannot see it on the bone. Feel it next to the midline, all right. The further lateral you go, the less prominent it is and quite often it is not felt at all. So, near the midline you start from anterior, start feeling posteriorly and the first bump that you feel that is the coronal suture. Now, I just wanted to talk to you about the tereon. The tereon is the junction between the greater wing of sphenoid. It is an H-shaped suture. The greater wing of the sphenoid down below, the frontal in front, the parietal superiorly and the temporal posteriorly, greater wing of sphenoid, frontal, parietal and temporal. Now, what I want you to do is, I want you to put your finger on the tereon and then turn the skull inwards and see where your finger points. Tell me where you see it. If you make your burr hole just in front of the tereon, front or inferior to it, you will expose three things, the frontal dural, the temporal and you will also get the periorbiter, all right. So, that is a very useful point. Some people call it the psychopathic point because if you do not get that point right, the surgeon becomes a psychopath if you are assisting him. Now, quite often I have noticed that people put the burr hole out here, you know, junction between just behind the psychomatic process of the frontal. Now, that is not right because that will only give you the frontal dural. Put your finger on it and have a look at it yourself and secondly, that will give you quite a cosmetically bad result unless you plug it, all right. Now, how many burr holes would you place for a craniotomy, whether you put one or multiple, that it kind of varies for older people, generally put in more because the dura is stuck and so you might tear the dura. But otherwise, if you have one burr hole and you have got a craniotomy, you can manage quite well, particularly if it is frontal or parietal. If you want to go across the sphenoid ridge, you may want to put one on the tearyon, in front of the tearyon and then one frontal so that you can go across the lesser wing easily. Whether you put it on the midline, suppose you need an inter hemispheric approach, you want to get as close to the fox as possible. Would you put it on the midline, just off the midline, what is your feeling about that? Yeah, well, you know, what happens is that if you are careful with these perforators, getting onto the sinus, you will never damage it. In fact, when you are doing a posterior fossa, if you want to do a posterior fossa craniotomy, if you put a burr hole, bang on the tocular, you will practically never damage it, perfectly placed on it. But if you are a little worried about it, you could put it just off the midline. You may not get too close to the fox, but try getting it onto the midline, you will find that it manages quite well. As far as burr holes and craniotomy is concerned, I will just show you some cases now that we have done and then I will get some feedback from you about what you think you would do. This is a boy who came to us, his left hand was totally clenched like this, but he was able to move his right hand well. He had dystonic movements, we made a walk, you can see his left leg circumducting a bit and his left hand totally clenched like this. So, a neurologist saw him and felt that this was more of a dystonic problem, felt that he had a lesion, this basal ganglia, got an MRI done and this is the MRI. You can see that it is located deep in the capsule ganglionic area, it is partly solid, partly cystic. It is not really extending into any of the opecula, but the superior part of it is cystic, there is a central area that is enhancing, the solid portion. The cyst wall does not seem to be enhancing, that is a sagittal view which gives you the impression that it is deep, it is not really into the either frontal or temporal. That is the coronal view which shows that it is really kind of displaced all the deep structures. The question is how would you approach this, what sort of craniotomy would you do to get at this and what are your concerns? We have got this DTI and the yellow portion there is the, that is solid portion of the tumor and here you can see all the, the archaea fasciculis, the superior and inferior longitudinal fasciculi and the internal capsule there is medial to the tumor. Let us go a little inside, you can see the internal capsule medial to it, that is the unsinnet fasciculis, but here essentially you see that all the fibers have been displaced out of the side and it appears that going through the sylvanes seems to be a good option rather than going through frontal or temporal. So that is what we did, made a large flap there, did a frontal temporal craniotomy, got the sylvanes fissure in the middle of the field. In general I like to keep the head kind of horizontal so that your orientation is okay. So here we are opening up the sylvanes fissure, you could either use a needle and then very gently open up the whole sylvanes fissure, but finally you do have to make a cotysectomy onto the insula. So that is what we are doing right now, all slowly, now we have got a tubular retractor which we have inserted, this is about 1.9 centimeters in diameter and I found that actually this branch of the middle several artery was coming into the retractors a little too big which is why I finally removed it and just had one retractor placed in and here we have and then of course the whole principle is to stay within the tumor rather than do any dissection outside for fear of damaging the white fiber tracks. Now you could use the QSA but I find that sometimes particularly at the dips the QSA goes and gets away tumor too fast and then you might end up in white matter earlier but I do use it from time to time. So this is one situation at the end of it here we are just putting in an ultrasound to see how much of tumor we left behind, we did leave behind tumor medially onto the thing but ultimately when you look at it the frontal and the temporal opecular quite nicely preserved that is the postoperative scan we see medially on the area where the internal capsule fibers were displaced we have left tumor behind it, this was a pylositic astrocytoma. So we have left him alone and he looks happy, he started smiling after surgery and more importantly his hand opened up that was good and this is another guy who somebody asked him to show how he shaves his beard and he is doing all sorts of stuff maybe that is how he really shaves his beard that is his image. So we had a huge big debate before surgery wondering whether this was an extra axial lesion is it inside the ventricle because there is you can see this tumor in the quadigeminal system it is extending into the atrium of the lateral ventricle it was going into the body of the lateral ventricle I mean finally our conclusion was that this was an intraventricular tumor then somebody pointed out that it was attached to the tent over there is it a meningioma what do you guys think that is a T2 flare sagittal coronal with gado any other differentials you think of I mean this is the ones that we thought of probably in a pandemoma or some other glauoma or a meningioma. So how would you get at this the left dominant hemisphere one thing you must understand there is no one correct method how would you open the head now in this this approach actually is quite good except that when you are dealing with something down here the distance is huge and so finally when you have got a vascular it is going to be vascular you are going to be operating at a great depth you might get away with it so it is an option right wait hold it you have already done your craniotomy and now you have started the craniotomy what would you do you may need to cut the tent but you may not but I agree that that is an option. So what we did was we had a look at the DTI again and so here you worried about the optic radiation and here you see the tumors in yellow and wherever you look there are white fibers wherever you go isn't it and so what we decided was we would do this inter hemispheric posterior inter hemispheric approach and what we did was we kept the left side down so that it would aid in gravity falling away and marked it right on to the midline that is the sagel sinus we opened the bone we found that the dura was really really tense so what would you do tap the ventricle so that is what we did over here and you know you be surprised at how difficult it is to to tap a ventricle so we had put in ultrasound to see where it is especially when the patient is positioned and turn the head but a good rule to follow would be to try and go perpendicular wherever you are when you perpendicular to dura you should hit the ventricle but when you have to take into account that the ventricle would have shifted because of the mass so we usually make sure that we have the ultrasound into to guide us when you want to tap but how much help removing CSF does just look at that absolutely nice and like so now when you open the dura you find that actually the without even putting in a retractor the occipital lobe is nicely away from the forks and then you get at this turned out to be a very soft extremely vascular tumor completely surrounding the vein of Galen etc it was a pendomoma so we left behind tumor on the vein of Galen and the basal vein of Rosenthal that area but we managed to take off all the portion laterally now here's another boy almost the same situation 17 year old one generalized seizure no focal deficits that's his MRI and it's draining superficially and so we decided to do a similar posterior intramasphoric approach in exactly the same position as the previous one now in terms of opening the dura if you are going to get to the sagittal sinus you can quite safely go right up to the edge and make sure you do that posteriorly you'll find that there are several veins that that can actually get into it and preserve all veins try and preserve all veins when you get to the sagittal sinus don't hesitate to even extend the dura opening either superior inferior if you find there are veins there you might be lucky all you need is maybe 1 to 1.5 centimeters of access because with the angulation of the microscope you can take out fair amounts of the AVM so we've basically got some veins draining into the fox over there and we're not really sure whether that is the main area so we've just putting a occlusion on it to kind of see whether there's swelling hold it on there for about a minute or so and there was no swelling so we cut it and then we found that actually the main draining vein was was there inferior and got this there you go down there so we find this approach and positioning quite quite useful what I do is I just keep them lateral and keep the head up 45 degrees in this turn the head down in our situation we need to keep things simple I think a three quarter prone would require a lot of people to make sure that there's the patient's position well good support so he doesn't fall forward so the lateral is one thing that even the technicians know how to position in and so we prefer to keep it simple this is a girl who had raised intracranial pressure obviously with left cerebellar dysfunction that's her MRI looks like it's a fourth ventricular mass or probably from the worm is there you can see a little bit of fourth ventricle seems to be going out into the foramen lusca on the right side so a regular midline posterior fossa mass and girl could be a medulloblastoma or ependomoma or something what I mean we've been doing is once you do your craniotomy typically how do you open the dura how do you open the dura and the posterior fossa and what are the things you need to watch out for so basically when you're opening the dura and the posterior fossa you've got to watch out for in children particularly where the occipital sinus might be quite big and even the circular sinus can be quite big and so you cut the dura on both sides put clamps and then cut and then tie and this sometimes I find quite cumbersome and ultimately when you open up the whole both cerebellar hemispheres and you're getting into the ventricle through one side one Tilo Velo tonsil approach it almost seems wasteful to open both so what I've been trying recently over the last year it seems to work so far is open the thing on one side and here we've got rise and cut the circular sinus we're far away from the midline and so we haven't gotten to the occipital sinus at all and we open the dura on one side alone and curve it towards the midline like a flap and so when you get it to the midline here reflected with silk sutures medially and then you have the entire midline even some of the opposite side you can see and then the axis for a Tilo Velo tonsila approach is between the vermus and the tonsil all right and we're going into the right side because you remember the tumor was getting into the lusca on the right side on the scan so that's the vermus there we're cutting open the arachnoid and getting into the Tilo Velo tonsila groove and it's amazing how if you open this groove from the lower end to the upper end you can actually see the entire flow of the fourth ventricle to the aqueduct you don't need to split the vermus at all and then you have a very good axis and the rest of the you wouldn't believe that I've not opened the dura on the left side because if it's I'm effectively in the midline so I find it useful doing it on one side and the great thing about it is that you can close the dura completely I'm a great believer in Dural closure and the vermus is safe so all this mutism and all that is this was a medulloblastoma all right thanks a lot