 I just want to make one comment. If you have a bleeding in the ventricle, the most important thing is that you keep the scope inside and what he is telling, keep on rinsing. The worst you can do is once it starts bleeding, take off the scope because then you have no more idea. Then you want to go back. You even will not find the way to the ventricle. You have no idea where you are. If bleeding will occur, it mainly comes from manipulating the scope once you're in the third ventricle where you just see everything which is in front of the lens. So if you turn the endoscope to all sides and you may do some harm to the septal vein, for example, and then suddenly everything is blue. You have no idea where it comes from. Keep there, keep on rinsing and it takes a while and then you get after a while you will see what was going on and then maybe it's important to put in a ventricular drain at the end of the procedure. For me, I think it's much better to keep it in the hand. I mean, this is a discussion we had a decade ago but there were a couple of neurosurgeons who said you must use a fixation device for a ventricular colostomy and it's dangerous to have it in your hand. For me, it's more dangerous to keep it in a fixation device because if you have the endoscope in the third ventricle on a fixation device, just somebody must come to the fixation device or an anesthetist is going to the table. That's enough that the endoscope moves and does some harm to the ventricle whereas if somebody keeps it in his hand, he's concentrated, he looks to the monitor and never try and play around, that Pernitski always said, don't play around. I mean, if you have a huge form of monorail, then it's possible that you can move the scope but if it's not that large, you must be aware that it's fine on a straight view to the third ventricle, to do the ventricular colostomy but don't try then to show you the posterior part of the third ventricle because then it may happen that you do some harm to the phonics or to the vein. Don't play around. And for the approach, of course, I'm sure you're doing the transfrontal for all these ventricular colostomies. You never go transcolosal for ventricular colostomy. That's the same, yeah. And for the colostomy, I must say, even for the colostomy, there's a lot of discussion about it because I had not a single patient with a seizure after a transfrontal approach to the colloid cyst or never because it was all discussion. You do a transquarticle approach. You do some harm to the cord. I've never had a single patient who had a seizure and for me, transcolosal for colloid cysts is only in patients with very small ventricles. Sometimes you have a large cyst with small ventricles. Then I think it's a good idea to go transcolosal. Otherwise, with large ventricles, I always go a transfrontal. Reventricular colostomy. I just want to show you 11 years after ventricular colostomy, just a patient who had some bleeding, interventricular bleeding. You still find the spots. That's how it can look like 11 years after ventricular colostomy. This tiny little hole. And we did ventricular colostomy again. Just interesting. After 11 years, you know, it can occlude again. Then we did that plexus carcinoma. In cases we talked about it, you can do a ventricular colostomy and take biopsy from this tumor. Supercellocyst. I think this in a young child. That's very interesting. Supercellocysts coming up to the front of Monroe. It's always important if you have a cyst, if it's possible to drain it to both sides. That means from the one side here into the ventricle and then of course drain it to the cyst turns as well. And that is the typical appearance of a supercellocyst. And in these cases, we use the bipolar or the monopolar a quarter first to get these, all these, this is a bipolar to get the vessels on the arachnoid occluded and you shrink the capsule of the cyst. It can be nicely done. And keep on rinsing during the procedure. We are continuously rinsing. And once you have that coagulated, then we use different devices like phogetic catheters or in these cases here we want to resect large pieces of the cyst to get abroad away. And then it's very interesting in these kind of cysts, look here, you have a completely distorted anatomy. That is the pituitary gland, the posterior lobe. This is the infondibulum. This is the carotid on the right, carotid on the left. Dorsum cellae, third nervous right here. You see the basilar, basilar artery, basilar apex. P1, P1 on that side. And then what we do, what we're doing is with contact to the dorsum cellae, then it's important in these cysts that you open, that you do a ventricleostomy as well, that you open everything to the interpeduncal and to the pre-plontine system. And then look through here and see if there are any more arachnoid sheathes right here, lilicous or whatever. This is free, this is the basilar artery, looking down to the furum and magnum. And then you have a good opening to both sides. And this will more or less guarantee that this cyst will no more close again. If you don't do that here with the ventricleostomy, I think you may not get a good result. So this is very important. Don't resect all of the cyst capsule. It's not necessary, especially where it's attached to the brain structures, that you do not get any bleeding from the vessels. That is absolutely sufficient. And at the end, you will see it will never disappear the cyst, but this is a nice result. You just have to take off the pressure of the surrounding brain. That is your goal. And he was really doing well this guy. No endocrine deficit and no signs of active hydrocephalus. Then if you have arachnoid cysts like here compressing the ventricle, now what you have to do is not only open the cyst right here, you have to find a site where you open the cyst to the ventricle. And intraoperatively, you see here we are now in the cyst. We've entered the cyst. And you can nicely see where the ventricle is behind. It's a different color here. It's a different color. It's like some bluish. And then again we coagulate the vessels first. And then perforate the cyst capsule right there. Quater is very safe at that point here. There is no big vessel just behind it. And then we use scissors, monopolar, and then we open the cyst wall to the lateral ventricle on the right side. Now we are in the ventricle. This is very important. So it's always, you know, to fenestrate the cysts to both sides, either to the ventricle and to the subdural space, in this case here. And then we open it wider and coagulate the remnants and get a good fenestration. And that's all what you have to do, just fenestration. It's not good to resect the whole cyst wall. That would be nonsense. You would get some bleeding. And the big advantage of the endoscope is here, once you enter into the cyst, you don't have to release, you know, the whole CSF that is in the cyst because everything else will collapse and you may have some problems, you know, by rupturing bridging veins, whatever, with the scope. You know, you can work in the water, in the cyst water. You don't have to release that. And this is much better for the outcome. So arachnoid cyst for me, definitely something for the endoscopy. And this is right after, of course, the cyst will never be growing away, but you see here, there was a lot of compression on the right hemisphere, and here now you see the sulci being back and a very good, nice, here fenestration to the ventricle. And that's the goal of the surgery. Subapendimoma, same story. Sometimes if you have, this is an old video, if you have a chronic hydrocephalus, often the septum pellucidum is gone. It had been perforated by the pressure. And then it is possible, like here, that you can see from one side to the other side. This is the one foramen of Monroe, on the right side, and the other one is just around the corner, on the left side is right there. So the septum pellucidum has been spontaneously, here it is, I'm sorry, there it is. Left foramen of Monroe, right foramen of Monroe. Because the septum pellucidum has been perforated here by the chronic pressure. And the subapendimoma is right here. And for these cases, I personally I resect them then microscopically. Even the colloid cysts, there's a lot of discussion about it, but I personally, I'm much quicker and better to do it microsurgically. I always start with the endoscope, get my orientation, know about the anatomy, and then we have special blades, intraventicular blades, you know, that we put to the Layla retractor, putting in, and then I go by the microscope by manually and take the cyst off. That is the result right after. Maybe just at the end, again a very old video, but just to show if you have some special pathologies like an intraventricular cavernoma here in the posterior horn, you see the corioplexus here, the same story. You go in with an endoscope first, get the orientation, and then for resection, everything where you have to do, I would say, major manipulation with two hands, I think it's better to do it, you know, under microscopic control than through an endoscope, even if you have two working channels. I know that my good friend Henry Schroeder from Germany, from Greifswald, he's much in favor to do the colloid cyst with a ventricular scope. It can be done, it's okay. He's doing it purely endoscopically, but I would say surgical time is at least twice, I would say, even three times more than with a microscope, because the problem is, even if you have two working channels, you cannot move the instruments through the working channels freely, and with colloid cysts, you sometimes really have to put in something that puts some tension on the capsule to get it off, and this kind of manipulation is not that easy through a working channel. Yeah, this is the cavernoma or just to show you some... this is how I do it, you know, with the microscope now. And this is nothing special. Just take the cavernoma off. And just to the end, Axel Pronecki, this is my mentor, my teacher, and yeah, we started. He started early 90s. I remember he was... he started in 1989, and started with the endoscopy ventriculostomy in 1991. This was the first ventriculostomy with the one chip camera where we today would say, oh, how could we do that? It was like in fog, yeah. Okay, thank you.