 What I will just show you in 2 minutes video of purely endoscopic clipping of MCA aneurysm through supra-orbital keyhole. Now you see this is the ICA bifurcation MCA you can see the aneurysm. And now you see there is one branch so I am still worried about always put a temporary clip then and now I am dissecting the aneurysm all around. Now after dissecting the aneurysm I want to see that the tips of the clip are properly taking whole of the neck. After confirming that I put temporary clip again before aspiration because if whole of the aneurysm is not occluded and if you do not put temporary clip the bleeding will come and it will spoil your endoscope and then read out. This is by microscope but still mini-cranetomy but this is about 3 years 4 years back and at that time I was using this incision just above the supra-cellular incision. This is the acomb aneurysm and you will see this incision I was wanting to say. This is the craniotomy and this is the bone flag and you see this is about 2.5 to 3 centimeter and above the aneurysm and then this is the optic nerve directly we have gone there split the fissure and open this carotid system. So initially I started with the incidental aneurysm and after doing 3-4 incidental I was confident enough one video is there in which the acomb bled during dissection but no problem it could easily be controlled. So acomb aneurysm bled during dissection but it could be controlled very well. So high speed drilling of bone in depth is required in neurosurgery usually for the following procedures. Antrachylinoids in Dowlings approach, Petrus pyramid in Kavase approach, Mastoid in Trans-Petrus approach and lateral margin of Rheumoforamen Magnum in far lateral approach. Now the aim of high speed drilling is that to convert the thick bone into thin bone. For craniotomy after bipolar coagulation Dura is cut over the optic canal. This is the intradural craniotomy and it is reflected down. Now drilling starts from optic canal to laterally over the cranioid. As you all know it is basically attached by two bases one with plenum and one with optic strip. So while making the core in the bone it is the isotope which is scored. Now whenever you drill sit comfortably one loop of tube or arm it should be looping in your arm so that if somebody pulls so the accident does not occur. Hold it like a pen the drill should be held like a pen. Now your hypotherm should rest on the skull or patient's head so that you have full control and your elbow on the arm chair of the operating. So like this it should be resting this should be resting. So now you are very much stable and use a light brush action paint brush action by smooth to and fro and side to side movements by drilling for drilling. Now angled hand piece is important in the drilling in the depth it is better to use angled hand piece do not press against the bone otherwise you are likely to go in. Drill in pulses don't do it continuously drill it in pulses put saline suck the bone dust and then again do it irrigate in between remove dust and wash in between the pulses and bleeding is controlled while drilling with dry drilling not using saline so that what happens the bone dust itself gets into the crevice and it stops bleeding or you can use bone wax but this dry drilling should be diamond drill not the cutting bar cutting will not stop the bleeding. Now cutting is done with the side rather than the tip so no cotton patty or surgy cell near the area of drilling you can keep if there is any bleeding you can keep gel foam because it doesn't catch the gel foam while you are drilling if even if it touches the gel foam it will not take it but it's better that there should not be anything else in the area you want to drill if you have a cotton there and if suppose it's cotton the drill and then your operation is finished. Use diamond bars at low speed for tactile control near the vital structures like carotid or optic nerve and frequent irrigation because the drilling also produces heat and which may be harmful to the optic nerve. Bring the drill tip in the view under the microscope make the drill on in the air when it is just seen make it on and now take the tip to the target where you want to drill and drill it in pulses like a paint brush remove the drill only when it has completely stopped. So now this is a case of a functioning para-cellar giant pituitary adenoma which was done by Dowlings approach combined with even kava size so now this is the extra dural dissection and I am just separating the endosteal and periosteal layers of the dura. So after initial cutting what I will hold just with the dural force and just peel it off and now you see this lesser wing of the spinoid is being drilled and now this is the meningo orbital artery which comes here which you have to coagulate and cut then only you will be able to see the interclinidine process clearly. Now this is the lesser wing of the spinoid this is the old videos it may not be very clear but still it serves the purpose and this is how you remove the ACP and there is a mistake here means this large chunk should not be removed in one go I should have drilled more and make it thin and now you see this just with the forceps I am just separating the endosteal and periosteal layers and now you see this is the cavernous sinus you can see and there is tumor in that sinus it is bulging there. So now just with the incision with the even needle you see the tumor starts flowing. Now this is again another extra dural drilling in a case of a kerotica ophthalmic aneurysm. So now this is the ACP is being coared and after the initial drilling further separated dissect the dura and now any overhanging bone is removed by 1mm and now this is the clinerd you can see which is in extra duraly and now we will core it out and then remove it. So this core should be the interior of this should be drilled and make it thin and now then this is disconnected from the strut and now you see the bleeding from cavernous sinus this is suggested that it is now almost done. So after disconnecting from the strut and I just deliver it with holding forceps and this is the anticholinear portion and now this bleeding easily stops just by putting it as we said and now this is the intradural drilling which was a giant hypofysial aneurysm. So this is the splitting of the sylvian fissure then ICA bifurcation again further opening of the arachnoid and now you see the optic nerve and this is the dura is being opened with the knife and the dura is dissected and reflected down to cover the carotid and optic nerve and now the drilling of the roof of the optic canal and anticholinear process intradural this is intradural and this is the roof of the optic canal which is being drilled. So now the dura is being opened so the optic nerve is decompressed you see there and this is the sheath proximal and distal carotid rings which are open so you get additional 3 millimeters of distance and it really makes difference there this is the proximal ring and now we can see the aneurysm much better and we got a space proximally to clip the aneurysm. So this is the suction decompression method there is already control in the neck and then distally the temporary clip is allowed and now I aspirate the aneurysm and once it collapses then immediately put the clip on the neck and this is now the neck is being clipped and now this patient presented with visual deficit. So now I am dissecting the aneurysm from the optic nerve so that and then patient immediate post-operative patient vision improved and always these large aneurysms 2 clips should be applied because one clip doesn't hold it so there has to be a booster clip and this is pre-op this is post-op this is the post-op enneagram same patient now how do you learn these techniques is by practicing in laboratory temporal bone dissection by attending various fellowships in skull-based surgery education seminars lectures conferences watching the videos of experts or attending the courses and workshops live and category and assisting the experts so this is the way you learn thank you very much for your time.