 So the principle of an aniscopic skull base is why to use why user aniscope is that you just can cover it with angled optics or zero-degree optics different areas of midline of the skull base that means not only the cellar region but you can always also go to the clivus or cranial or a cervical junction you can go to their cranial base and but we are focusing really on the cellar region because it's a good advice that really if you start an aniscopy you do it on straightforward cases like pituitary like perhaps and well circumscribed CSF fistula and you can mentally stage your surgery in three stages that is the nasal stage so try to get access to the anterior face of the finished sinus the finished stage where you deal with all these anatomic variations that means intrasphenoidal septi and there may be an intracellular or intradural stage but it all depends on these two stages that you're doing a good job on that. Again it's all about repetition so this is the region we're dealing about it and there are some landmarks you really have to memorize it's really that you just see that there's the medial surface which is just quite flat but you have always a kind of septum deviations so there's a big variety and that you really say okay I have the inferior turbinate the middle and the superior and the anterior wall of the finished sinus and these are the structures which you have to memorize and try to identify during surgery because it's just an unusual and if you start with the anoscope and this is just the bony view it seems to be quite simple because the number of structures are not that big but during surgery it's all mucosa covered this is a view into the maxillary sinus here's the crest on the the bony part of the nasal septum this is the vomere and these are the openings of the sinusinus during surgery of course the view is different because everything is mucosa covered and you might have tried traces of blood on your anoscopic optics and so this only the the bony substrate of your surgery and what you have to think of is that there the optic you use in anoscopy it's not microscopy microscopy is perfect in terms of geometry or it's a real image while with anoscopic surgery you have a kind of fish eye optics so it's a kind of distortion you get a quiet or a good adapted to it but you have to remember that the image is distorted it's not real image and it's good to have a certain method if you start anoscopic and a nasal surgery it's always about orientation yeah because there's some varieties it's good to to have a look at this preoperative CT scans to get clear about the individual patient anatomy and the first step is always to orientate from the flaw of the nasal cavity and to identify all the structures because it you will be surprised what you see if you stick in an anoscope you get lost because we don't use in general we don't use x-ray even navigation it's not of big use in that stage of the surgery look at the flaw of nasal cavity yes it sounds simple but it's a good advice then identify medial and lateral the inferior terminate then and the middle terminate and you see it's you don't have there in the sphenial you make you have a panoramic view but in the nose itself it's quite limited and if you go along the flaw of the nasal cavity that's the first stage of the surgery always go really quite at the base then you enter this region and in general it's quite easy possible without moving a lot the inferior terminate you see the nasal septum you see the quenna you see the nasopharynx and the tubal evaporation yeah and this is the first step of orientation and if you now have this the first step then you can go upwards from the quenna and it's about 1.5 centimeters above you may see the ostium of the sphenous sinus or you may see it not in most of the cases it's hardly visible without mobilization of the superior terminate but for example with suction you may feel a loss of resistance yeah if you tap against it and what's also very important is that there's an ostium of the sphenoid it's not in the middle or lower part of the sphenous sinus it's in the upper part so if you're happy to to find it yeah success first stage then don't go upwards but your direction of dissection should be downwards to visualize the flaw of the sphenous sinus that's quite important yeah not to do like this cluck cluck cluck cluck cluck and you end far too up in the ethnic cells you remember of course the mucosa itself may bleed yeah that may be sometimes a problem with the endoscopic optics but you have this sphenopalatine artery which it's origin just behind the superior terminate about here and which gives its branches up to the same nasus septum and which crosses your line of dissection and then it's you may sacrifice yeah it's possible but if you plan that's not the beginning but if you plan to raise a so-called nasus septum flap if you create a larger CSF fistula or you have to reconstruct the skull base it's not allowed to sacrifice this branch of the sphenopalatine artery but you have to memorize that you need a vascularized particle flap and you have to mobilize the mucosa with the artery inside so this is one beautiful picture from the Rotom collection just to give you the perspective at the coronal view of the entrance in the sphenocyanus and again this is the view we know from the inside of the skull and this view we also where we really see if we remove the entry of surface of the sphenopone we already have this nice view with endoscopy yeah it's not something exceptional you may see and this is not about doing surgery on these structures it's just to remember what if pathology extends more lateral or more superior to the pituitary gland when is there a risk for injury to the ath to the carotid artery or to the cranial nerves and you see if we respect the borders of the cavernous sinus and it's really impossible to do a major damage to the cranial nerves but as soon as you have invasive tumor and you're dissecting blind for example with a curret they may be in structures as risk especially the ocular motor nerve once again this is the panoramic view with a zero-degree optic if you have removed the surface of the ventral surface of the sphenocyanus and this is cadaver section from fresh frozen cadaver we just see what is behind all these bony structures so in general we only deal with this region yeah of course this is not a pathologic cellar so there's no tumor behind it it's quite flat but it's always important to verify your orientation that you identify this a cellar that you have the clival recess yeah you don't really visualize that if you have a microscope that you have the carotid prominence and that's so important was more it said is it may be really even very thin bone covered yeah and that makes pituitary surgery may lead to to lethal consequences if you just stick in your endoscope you see much more you try to work on all these structures it's really easily with a drill you're slipping or stuff like that that you may put the carotid at risk and you may imagine that this it's very difficult to control and even the optic nerve may be very thin from bony coverage and it's just good even if you only do pituitary surgery when you start endoscopy that you just with every case try to identify is the reason why it's so difficult is I don't know if you have our standard your navigation with every case we only have one machine and sometimes it's reserved for spine surgery and we don't use x-ray if you don't identify the structures yeah you may be really misled by the asymmetric intrasphenodal septi to complete a different trajectory because you're coming from one side perhaps you don't find the midline exactly and we saw cases where inexperienced people identified for example this region as seller and stopped surgery because of some bleeding and without getting some histology yeah it's possible it sounds so but if you have an endoscope at the beginning it's so unusual to use it you have some bleeding you are a bit stressed and really if you work on a very strict method just to identify your structures to know the individual patient anatomy with all the septi deviation and stuff like that and that makes you able to make a good job even if you're not an advanced endoscopist in general these are the structures what you call the medial optical kerotic a recess and the the lateral this is leading to the optic strut and which is part of the anterior climate process just an escopic picture yeah you see with a zero-degree optic this is the the seller with the this is kerotic prominence you see even in a specimen we made some damage when stripping off the mucosa to the bony surface of the correct prominence this is a also very large lateral critical optic recess and this is the the clival clival recess seller and it's just good to make a preoperative CT scan even if you have an excellent MRI a substrate for your surgery just to identify what regions are parameterized what regions how their intracranial septum is going to in general one side and even in general to one kerotic artery thank you