 I will show you this approach is for minor lesions, for specific pathologies. And I will show you, for example, this kind of huge paraclinoid aneurysms. You must do, you know, a larger approach. You would completely lost, you know, with that kind of procedure. But many of pathologies will fit to that kind of, let's say, mini craniotomy. So that's what I learned with Pernetsky. Pernetsky was not only enthusiastic with the endoscope, but with tailored approaches. And we started early on with the eyebrow incision that I still use for a couple of pathologies. I have come back for certain pathologies we did in mines via eyebrow. I'm going back to a more frontotemporal approach, getting a little bit more space. But for many pathologies, I'm still using the eyebrow incision. But this is a tailored approach for, let's say, professionals. You must have learned, you know, the larger approaches beforehand. And you must feel fine to work in a very limited space. That's the power. I learned it with Pernetsky. And for me, it's interesting, the same with the endonasal stuff. When Kasam looked how I was doing that, he was laughing. And he came to me and said, you must be a Pernetsky pupil, because everything is very small and narrow. And he said, somebody needs more space to work in. I learned, you know, to do it in a very narrow space. And once I'm using no larger space, he said, gosh, me, that's so easy, you know. So if you use a narrow space, but there are certain points that are very, very important, otherwise you get completely lost. So first of all, the eyebrow incision is good for a subfrontal root. That's very important to know. So, you know, with the fingertip on the skull base, if you just come from here, you know, I do what you say, cosmetically, it's not that nice, but I always put a titanium clamp in here, and then it's nice. We do the burr hole. I'm not using a trafine anymore for decades. I'm not using a trafine, you know, learned by Pernetsky just to take a drill. The good thing is with the drill, you never push the dura aside from the inner tabule of the bone. So with these approaches, we almost never have to do any dura suturing. Very rarely we do dura suturing at the end, because the dura is still adherent to the inner tabule of the bone, and just close the dura, and that's it for these mini approaches. If you have a larger craniotomy, of course, and a lot of CSF release, so what I do is we drill the burr hole here, and then we take, we'll show it to you later on, a carousel. We just a tiny little burr hole, and then we take a carousel and just widen it by taking it apart of the inner tabule of the bone to both sides so that the craniotome fits in. And then, you know, we take off a mini craniotomy, which is from here. This is lateral to the superior temporal line, here going to the frontal sinus, lateral edge of the frontal sinus, and then take the mini craniotomy right here. But as you see, it's a subfrontal approach. It's impossible to come to the temporal fossa, whatever. So even you would see that I'm doing most of the middle cerebral artery aneurysms this way, subfrontal. But I will show to you that I'm in favor of doing most of the middle cerebral artery aneurysms subfrontally. I'm more in favor of going subfrontally rather than charionally. But this is certain hints for that. If you have tumors, you know, at the skull base, and you come from, let's say here, the super orbital edge, in the depth, you know, you have angles that you even can cope with tumors three or four centimeter size, mainly located at the supracella area. So the eyebrow incision with the super orbital approach is good for lesions, mainly lesions, that are located supercellally. So if you want to use that minimal invasive and maximal effective approach, it's very important that you do a good study of the diagnostic images, that you determine the surgical corridor you need, and it must be then an individualized tailored approach. And for that reason, positioning, for example, is important. This is a publication by Reich from our Mindscrew. Positioning is important, for example, if you go for aneurysms. If you would go, for example, with a super orbital approach for anterior communicating artery aneurysms, what do you think? How much have you rotate the head to come ideally from a super orbital approach to the ACOM? Would you keep it like this, zero degree rotation, just a bit or even more? How much? A little bit more. For anterior communicating, I go 30 to 45 degrees. But for middle, several artery aneurysms, because we're not coming from temporal, it's less, just 15 degrees. For PCOM, 70 degrees, looking to the lateral surface of the carotid artery. So positioning is very important if you have such a limited corridor, so that you ideally look at the structures that you need. And we flex it first, then we rotate it, and at the end, we recline the head. Not for all of the lesions. Something that I learned I would never do or I no more am doing is everything that goes to the olfactory groove. Olfactory groove is difficult if you do the craniotomy right here, because the problem is with the eyebrow incision. The height of the craniotomy is maximum 2.53 centimeter, not more than this. So if you have the edge right here, and you want to look to the cribiform plate, the angle is no more possible. With Pernatsky, he took the endoscope and with a lot of fancy things, you can cope with it, but you really sometimes have to struggle. So for this kind of lesions, I do a frontal temporal and the hairline incision and have a larger craniotomy so that I can get the angle to the cribiform plate. The craniotomy plate for me is not good for with an eyebrow incision. So this is just an example, nothing. I would not do this super-obviously. This is something I don't know if you would have done a kavasi approach. That was an interesting patient. He had the MCA aneurysm and that was a trigeminal neuroma. And I did the neuroma first. Actually I did not do the kavasi approach and not the dolenge. I just went sub-temporal, took it off completely, but I had some problem with the labese vein. Again, I got some venous infarction. I could take the tumor off completely and this didn't do that much harm to the patient. And then in the second attempt we did the MCA aneurysm. We did it on the same time. But just I want to show you step by step now how we do it. So before we start doing any incision from whatever craniotomy we do at the skull, that's what I learned with Pranetsky. We always draw. What would we draw on the skin? What is important if you draw? Your incision on the skin. What determines the length of your incision and the shape of your incision? What are the factors that determines your incision? Anatomical structures, yes. For example, if you're at the eyebrow, what is important? What don't you want to do? Frontal sinus. You don't want to open the frontal sinus. This is a problem, absolutely. If you open the frontal sinus with such an incision, you don't have any tissue that you can take, you know, from the surgical side. So then you have to take some artificial graft or taking from the thigh or whatever some something to reconstruct the frontal sinus. You don't want to open the frontal sinus. So how can you determine the frontal sinus, the edge of the frontal sinus? CT scan, but much easier. You can palpate. In almost all of the patients, you can palpate your frontal sinus. If you really carefully go here from here, I can tell you here's my lateral edge of the frontal sinus. There's some bulging. You can really palpate it in the upper part. You can palpate it. Of course, if you have a CT scan, if you want to have navigation, you can ideally draw it. But you can, in almost all of the patients, you can palpate it. And then, of course, you draw the lateral edge of the frontal sinus, first. Second is, what else don't you want to injure? So you draw, you know, where the super orbital super orbital will run through, which is here. And then what else is needed? You have the anatomical structures now. Where do you want to place your burr hole? And as I said, you want to place it lateral to the superior temporal line. Superior temporal line can be palpated as well. So just lateral. We do it because there's the temporal muscle right there. So you have the muscle that is covering there, and we put in the titanium clamp. So that is where we want to place our burr hole. And then, what else? The size of your craniotomy. So then we draw the size of the desired craniotomy. And by having all this drawn on the skin of the patient, that gives you then the length of the incision that is needed. And this is something which is true for whatever kind of approach you will do. At whatever side, always think of the anatomical structures. Where will you place your burr hole? What should be the desired craniotomy? And this gives you your incision. Just to make an incision somewhere and not thinking about why is it that. And at the end of the procedure, that's what I learned with Pranetsky. Always go back and think of what has been needed. Sometimes you come back and think it would have been better to make the incision two centimeters longer, or the craniotomy was too small. But sometimes you will find out, I have exposed three or four centimeters of the brain, which was just not needed. And then step by step, you come to a tailored approach that fits with your individual qualities. Some people need more space, happier with that. Others are fine if it's really tailored. So by doing that, drawing all these structures we're talking about. And then, as I told you, once we have done the skin incision, which is here about four and a half centimeters, doing the incision. We used a couple of different things, how retracting now the super orbital muscle and the temporal muscle. And we have seen that sutures are still best. Because if you put in any retractors, it will take some, it will take place. But you see burr hole, kerosene. And then with a craniotome, we take off this piece of bone, which has in size some three centimeters, two and a half to three centimeters. It's important that the heat here is at least three centimeters, because otherwise it's difficult to go in. What I've learned with Pranetsky, honestly, I never missed a ventricle. You can puncture the ventricle via this super orbital approach, and he's correct, always perpendicular. Of course, I mean if there is a small ventricle, it may become a sum from the beginning, but you must be able to puncture a ventricle, especially in the ruptured aneurysms. Because if you have a full brain because of a hydrocephalus, you must have some CSF release. And then you see, I just want to show you, you can split the sylvian fissure, coming subfrontally. You can split the sylvian fissure and go nicely to an aneurysm. Here the mid-cellular artery aneurysm. You see this is the temporal M2 branch. This is just an animation that you see where the M1 segment is. The temporal branch, the M2 branch, the frontal one is right here. And you can go all around the aneurysm and then clip it in normal fashion via this approach. This is possible. We have now the ICG available and do ultrasound Doppler. We have realized after clipping that there was still some remnant. And often in aneurysm surgery, you have to re-adapt the clips. Don't put on a clip and you think everything is fine. Always dissect once you've clipped the aneurysm. We're using the ICG, the Doppler probe, especially the Doppler probe. If you see that you did some harm to the main vessels. This is not good just to say, oh, it's like this. I cannot do it any better. No, you must do it better. And then you have to relocate the clip. Sometimes you have to reconstruct an aneurysm by using several clips, not only for the giant aneurysms, even for small aneurysms, sometimes use two or three clips and reconstruct it that way. So be very careful with that. But what you've seen is, what's a little bit too fast is you need some space, some corridor. And what you may have seen is, once we've done the craniotomy, what we'll always do is then we do an extradural drilling at the orbital rim. But just the inner tabule, and this gives you much more space, much more space to work in. And the second border I've shown you is CSF release. I know that some people put in a lumbar drain prior to, for example, surgery on a ruptured aneurysm if there's some hydrocephalus. I'm not in favor of that, because with lumbar drain, I cannot control the amount of CSF release. It drops very slowly. Whereas if you puncture directly, I have the influence. I can influence the amount of CSF getting out. I always use a cushioning scandula and then put in an external drain during the surgery and just let it drip. And the interesting thing is, if you put in an external drainage on a closed skull in a ruptured aneurysm beforehand, and you have CSF release, you may create a re-rupture of the aneurysms. We never do that. But if you do it intraoperatively, once you have opened the skull, I never ever had this experience that by puncturing in CSF release, even with a huge CSF release, that there will be a re-rupture and premature rupture of an aneurysm. Of course, aneurysm surgery, I don't want to talk too much about aneurysm surgery. But from the strategy, the next thing is you always have to analyze beforehand where is the rupture site of the aneurysm. And your dissection must be adapted to that. That means never, ever do anything at the rupture point of the aneurysm. For example, let's speak about ACOM. If you have an ACOM aneurysm looking to the chiasm, my dissection will be always along hoipners artery. That means to the gyrosrectors, not to the chiasm. I leave that. And coming from that route to the ACOM. If it's located posteriorly, it's just the opposite. I go along the chiasm. So always think, where is the attachment? Because if you deal with the attachment of the ruptured site, then you will get that premature rupture. And if you always think about it, you do it in a correct way, premature rupture is absolutely has become extraordinary. Premature rupture, for me, for aneurysm is a long time ago. It should not happen. Of course, it may happen at the last step when everything is free. But then you can control it. But premature rupture that you have not seen all the main vessels that are important, this is something you should avoid, because this makes it very, very difficult. Of course, temporary clipping, this is another point. I'm not that much in favor of temporary clipping, but except that a lot of people do it every time. But this is just for the aneurysm. And then you see this is the clapped aneurysm, and this is the size of the craniotomy that's been needed. Pathologies, I won't roughly go through that. I did more than, meanwhile, I think more than 400 cases. And you see 70% were ruptured aneurysms, because people are saying, oh, you're just using it for non-ruptured ones. No, no, I use it for the ruptured ones as well. And mainly for the acomb, as I told you, 90% of the acomb I'm doing it with the eyebrow incision, 70% of the middle cerebral arteries and inter-cerval arteries. Posseous circulation has become very, very few because we have a good endovascular team. And that's what I want to show you, just ophthalmic aneurysm. The last one I did, I think, is a couple of years ago. The giant ones has to be done, but otherwise it's all been done by the endovascular people. Just to show you, if you want to come to an aneurysm, medially located from the carotid artery, like from the ophthalmic artery, what kind of approach would you choose right here? Would you come? This is the right-sided ophthalmic aneurysm. You would come from the right side. If you come from the left side, I will show you, you come from the left side, contralateral, is ideal because then you work, look, this is from the other side. Left-sided eyebrow incision. This is your left carotid artery, left optic, optic chiasm. This is the right optic. And look, the aneurysm is here. So if you come from the other side for the medially located carotid aneurysms, you look directly to the aneurysm. Sometimes it's infrachiasmatic. Chiasmatic, it's inferior to the optic. Sometimes it's superior. But coming from here, you look to the origin of the carotid artery. You see the carotid artery making a loop here. The ophthalmic is right there. You see the ophthalmic there. And once you have this anatomy, then you can put a clip and you don't have to deal with the optic nerve as you would have to do it if you come ipsularly. And that can be nicely done here. Then put in the clip, just parallel, and then occlude that aneurysm. And then at the end, inspect, of course, your thymic artery if everything's fine. That was not that difficult here. This was a non-ruptured. And this is the opposite I just want to show you. In this case, because this was ideally because you've seen there was a mid-cellular artery aneurysm as well. And this was mainly looking to the temporal lobe. And in this case, you can even clip a mid-cellular artery aneurysm from the contralateral side. You can even split the sylvian fissure from the other side. You see this is left-sided, eyebrow incision to the right mid-cellular artery aneurysm because it's located right here. If it would have been located down and going to the frontal lobe, I would not do it. And I would do another approach from the ipsilateral side. But here it was possible to clip that aneurysm as well. So it depends always on the situation. The disadvantage, HOPF has published some 12 or 15 bilateral mid-cellular artery aneurysms having been clipped through one eyebrow incision. The disadvantage, if you go to the other sylvian fissure, you will not see it here. But you need some kind of retraction of the frontal lobe. And you will have some problems with the olfaction. So if you retract too much the frontal lobe, some people may come anosmic. So what I've learned is if I do it now, I dissect the olfactory from the rectus gyrus and put the retractor on the rectus gyrus, but leave the olfactory above. Because otherwise, by just retracting it, you may do some harm to the olfactory nerve. Many people look for that. But you will be, even with the larger approaches, you will be surprised that sometimes this happens. And you do not realize it. If it pops out at the crib from plate, you will not realize that you did some harm to the olfactory. This is another three aneurysms. We clip ipsilaterally. But just to show you that it's possible, this is another mid-servil arch aneurysm that's been clipped first. If you have multiple aneurysms and you want to clip then in one session, you must have a plan where you start first. Because if you clip an aneurysm, let's say here we have three aneurysms, you clip an aneurysm first where the clip branches then are in your way to approach the other ones, that's bad. So you must have a plan step by step where you start and where you end. Here we started from the mid-servil, and then went to the other aneurysms. And this was another one on the other side. You could see here the same story. I'll show you the other Silvian fissure. And this could be clipped as well with special Pernetsky clips. So endoscopy may be of some value. I'm using it very rarely in aneurysms, but in some aneurysms it's good. This is another case here, a raptured aneurysm of the acomb. You see this acomb aneurysm here looking inferiorly. And there was a small aneurysm at the carotid bifurcation on the left side. We approach it from the left side. You see it here again. This is the acomb aneurysm looking inferiorly. And this is the small carotid bifurcation aneurysm that you could see here just two or three millimeters in size. And now you see again here putting in external drainage. This was a raptured aneurysm. Absolutely important. Without CSF release, you cannot do a traumatic surgery. And this is now dissection optic. This is now a left-sided approach. This is the left optic. Carotid would be here. This is the A1 segment. And you see the aneurysms here. And the aneurysms looking inferiorly. And the attachment is here to the optic nerve. So never do anything on that edge here. It's not important. You need just the neck. But here still it does not absolutely clear. Is this aneurysm? Where's the acomb? This is the A2 on the other side. The other A2. The ipsilateral is here. And now you see this is acomb. This is still part of the aneurysm. But where is hoipness artery, for example? Where is hoipness? So we put in an endoscope. And we want to look behind the aneurysm. That is right here. And you see right here that is the aneurysm. That is the A2, the contralateral. And you've seen here that was the hoipness artery from the other side. So with the endoscope, you sometimes can look around otherwise hidden structures and identify important arteries. So now I know where the hoipness is from the other side. I see the aneurysm right here. This is the A1. And so I got more information before clipping. Clipping with the endoscope is very difficult. Because then you have to use fixation devices. You see it again, this is the A1. This is the hoipness artery, the ipsilateral hoipness. This is the A2. And the acomb is just behind this part of the sac here. You will see it again right now. A1 ipsilateral, A2 ipsilateral, hoipness artery ipsilateral. Aneurysm, aneurysm, A2 other side. And the acomb is right here. You will see it. I just mobilize it gently. And this is the acomb. Here is the acomb. That's the acomb. So this aneurysm is mainly from the edge A1, A2, on the other side, right side. So having this information now, here you see this is the acomb. Now we know how to, we can clip the aneurysm, step by step, get the control of the acomb, and then clip it. And once you have clipped, you have to use again inspection with a microscope. And I think here we did it with an endoscope. And now we can, once you have clipped the aneurysm, now you can go to the attachment. Now you can coagulate the aneurysm. You can open the aneurysm and see what's going on. That's what we did here, step by step. ICG is very helpful, but ICG is not 100% sensitive. I had now an aneurysm where we do the re-angiogram, and ICG was absolutely perfect. And I had a small remnant in the aneurysm that I did not detect during the surgery. What I want to show is, even if you have clipped an aneurysm, it's not finished just by putting on a clip. You must carefully inspect the surgical side. And now you can deal with here. That's where the aneurysm had ruptured. Once you've clipped, you can deal with that. And now step by step, I shrink it by coagulation. And then you get a very good overview. This is the chiasm now here. Optic, ipsilaterally, chiasm, other optic nerves. If you have an aneurysm here, opening the falciform ligament is easy doing it intradurally. If you need it, here it was not needed. So now you get more and more good control about the situation and shrink the aneurysm. And then with the Doppler at the end or inspection again with the endoscope. And now you can see this is the hoipness on the other side. And this is the A1 on the other side. A2 other side, hoipness A1 other side. Just looking behind the aneurysm sac with an endoscope. So therefore, it can be helpful. But otherwise, in aneurysm surgery, ruptured aneurysm surgery, endoscope is sometimes very difficult because you have blood, CSF, everything in front of your lens. It's not that easy. Prenetsky clipped some aneurysms endoscopically, but rare instances, I would say. Very rare instances. OK, and this is the other aneurysm. Just to show you, that has been clipped before. And just want to show you that was the, no, this is the one, the A1 one. This is again, this is the other one. This is the carotid bifurcation. That was not that difficult. It was just at the top, 2 centimeter. And that could be easily done. So I just want to roughly go through that. Yes, the results. Just to show you the incisions. The thicker the eyebrow is, the better it is, cosmetically. But even in early patients, you can rarely see often that there has been an incision. Usually what we do is we do a subcutaneous and intercutaneous suturing. And that's it. Pathologies that you can deal with tumors. I just want to show you, we talked about doing these endonazily. Or if I do these tumors transcranially, I use the super orbital approach for everything which is at the tuberculum cellar and plenum sphenoidale. This is ideal. But just want to show you the same story for the cranioferringiomas. Just an example. If you have a tumor which is located supercellarly and here infrachiasmatically, you always have to work in between neurovascular structures. Infrachiasmatically, that means in between the skull base and the chiasm, or in between the carotid and the optic nerve, the optic carotid window, or even more lateral retrocarotid window. But you always have to work through windows. So basically, by this manipulation, you can do some harm to these structures. If you come from below endonazily, these structures are far away and you have the tumor first and the structures are pushed away. So you don't deal with these structures. You can do, as you can see here, and by preventing here, I'm not sure if this was a cranioferringioma, but preventing the pituitary stalk. But I just want to show you, if you use these approaches, you always have to work through different kind of windows. Just no goes, as I said, for superval approach. Sphenoid wingman in germa, everything which is lateral to the anterior clandar process, no way. It's a subfrontal approach. This has been done paternally, this tumor. If you have space occupying hemorrhage from aneurysms, no point to do a small incision. And if you have these kind of large petroclival, whatever, skull-based tumors, no way to do a mini craniotomy. It's a tailored approach for small lesions. And I would have loved if the papers from the Pernetsky group, that's not from me, from Reich and Hopf, would have stressed that. And the comments from Dorland, for example, were absolutely correct that he says it's a tailored approach for small lesions. But for complex skull-based lesions, no way to cope it with such an approach. Thank you.