 Good morning everybody and I think I will be taking up a very basic aspect of neurosurgery. I think we are all aware of how to do flags, flaps and how to do a lot of neurosurgical procedures. I will be brushing up with the basic principles I think we all should know and what are the basic principles of the skin flaps and craniotomies in neurosurgery. The thing is they should provide the basic adequate surgical exposure. We know that without the surgical exposure it is very difficult to do the neurosurgical procedures and complication basically rises because of the wrong placement of the flaps, positioning and wrong approaches. So the another aspect is that there has to be the flap should be made such that there is the minimal brain retraction and there is the minimal damage to the surrounding neuro vascular structures and this is only possible if a flap is correct there is adequate brain retraction, relaxation and there is adequate direct approach to the surgical lesions. So another aspect is the base of the skin flap should be wider and there is the preservation of the neuro vascular bundle of the scalp flap so that the patient is having the sensations of the flap pulling surgery otherwise if we are cutting the nerve spy of the flap patient have a lot of sometimes this is seizures and loss of sensations they keep on complaining later on. So we should take care of that also so what are the landmarks you all know. This is the nasion, this is the bregma here, this is the lambda, then this is the ion, then t-reon you know that it is here, asterion here. So these are the basic landmarks for placing most of the surgical crinotomies. So one more important aspect is then how to make the surgical landmarks, how to know that where is the skin marking of a particular brain lobe structure so that we need to know then where is the frontal lobe, where is the silmin fissure, where is the rolandic fissure, where is the temporal lobe and how do we do it. So for that we all have to know what are the Taylor-Horton lines, I think you are all aware of that. So for that there is a base line it is drawn which is from the lower aspect of the inferior orbital margin and the superior aspect of the external acoustic miatus. So thing is that then this is the zygoma, so this is the zygoma, this is the nasion, this is the anion. So we have to make a line, imaginary line from anion to nasion. So divide into the four quadrants, there is the 25 percent, then 50 percent, then 75 percent and then this is the 100 percent. So it is equally divided into four parts. So thing is then just at the level of the t-reonal point, so you draw a line which goes up to the 75 percent of the bisecting line, this is the 25, 50 and 75 percent draw a line. Total line for the midpoint of the zygoma to the 50 percent of the line. So just you have to draw on the patient's skull. So then what we get is that, so these two lines bisect here. So the initial part of this line, this is the sylvanes fissure, this is the normal structure and this is the rolandic fissure. So for example what we do is that many times we have a temporal tumor, for example tumor is here. So there is no point making such a big flap here. So the exposure is very important. So once you have drawn, you know that these are the normal landmarks. Then correlate these things with the MRI, especially in sagittal and coronal as well as in the exiled section. So how much the sylvanes fissure is actually displaced up, if the tumor is in the frontal lobe sitting up, then how much sylvanes fissure is pushed down. So according to that you can tailor your flap. For example the tumor is here. You know that this is the sylvanes fissure, it may be pushed up maximum by 1 or 1.5 centimeter. So your small flap is enough. So that is another thing is that there is a tumor for example sitting up in the parietal lobe. So there is no point making such a big flap there. We may be missing that this flap may be positioning our flap may be a little anteriorly into the frontal lobe, so while the tumor is back. So in that situation you have to have a sagittal aspect of the MRI. So see that what is the exact location of the tumor or the particular lesions in that. So while these things are important for that. So what are the neuro vascular splice of the scalp? You all know that there is just a brushing of that. There is a supratochlear nerve, suprorbital nerve, then the zygomaticotemporal nerve, auricular temporal, lesser occipital and the greater occipital nerves. These are the major nerve splice of the scalp. Then occipital artery, posterior auricular artery, superficial temporal, zygomaticotemporal, suprorbital and the supratochlear. This is the arterial splice. So our flaps should be based according to these vascular splice. So the base of the scalp flap should be on these arteries. We are not going to cut these artery and make the flap on the opposite direction. So that otherwise the vascularity is always compromised. Then the surgical planning. So it depends upon the location of the lesion. So where is the exact location of the lesion? Whether in the temporal, frontal, parietal, occipital, suboccipital and the cerebellar. Where is the lesion? Then the position of the important structure. So what exact neurovascular structure we are going to encounter while making a flap? For example, in case of suboccipital craniotomy, exact location of the, this is a transphyssinus, sigmoid sinus is important. And the same thing is that if we are making a flap in the parasitic location, so a spherocytocinus that we need to know, then other neurovascular structure is important. So in the contingency flap of extension in season. For example, in cases if there is a certain brain bulge, for example. So there has to be a contingency plan then what next? How to extend our flap? In case of emergency, for example, the tumor is in the tentorial region. So we have made the suboccipital craniotomy for the posterior fossa. And many times these tumors are extending through the tentorial into the supra-tentorial compartment. So thinking that we will be able to take out the tumors from the suboccipital approach only. But sometimes you may not be and there is some problem. So you have a second plan B so that you are going supra-tentorially making a craniotomy above also. Then by going from above and the below with the combined technique, you are able to take out these tumors. So you have to have a plan B in your mind. So every flap has to be in such a condition, the brain retraction should be minimal and it has to be gravity dependent. So the important aspect for that is the how to position a patient. So the surgical position should be such that there has to be the direct surgical access to the target and there is a gravity assisted retraction and ensure the venous return and the potency of the airway so that neck is not turned too much so that there is a lot of compression of the jugular veins. So that if the compression of the jugular vein is there, the patient is going to have intraoperative lot of venous bleeding and there may be the brain edema and the swelling may be there. So there are decreased venous turn. So make sure the patient neck is such a position and it is little higher up as compared to the heart so that the venous return is very important. So then the surgical ergonomics so that the position should be such that the surgeon is not tired during the surgery so that his hand rests are proper, his position is such that because if the position is awkward, you are tired, you are tend to make mistakes and at the same time your hand dexterity is gone and there is lot of tremors into your hand. So that the position is such that you are comfortable. So the surgical position is supine, then it may be prone, sitting, semi-sitting, then this is a conquered position for the pineal regions, then the park bend position for the posterior fossils and the lateral position, then the general principles of the surgical flaps. It has to as I already told you that the exposure of the legion is important, neuro vascular supply and another aspect is the cosmetic effect. So all the surgical flap should not come to the exposed part of the face so that it is cosmetically it is important. Your craniotomy also should be such that they are not much visible, there should not be any burhole on the forehead and if at all you have to do is that. So in that case you have a some sort of plugging mechanism available so that in future the patient these scalp actually retract into the burhole and it gives a very bad cosmetic result. So you have to be careful, you are not going to place any burhole in the forehead and the second thing is that the incision should not come to the forehead and it has to be concealed in either in the hairline and if in case you are going the supraorbital it has to be into the eyebrow incision. So it is inside the eyebrow. Then what are the types? Random patterns. So basic aspect is that your length should not be more than 1.5 times of the breadth of a flap so that the base of the flap should be broader. If the base of the flap is narrow so it means that the terminal end of the flap the vascularity is less. So it is likely to have ischemic changes, your surgical wound can get away and if the blood supply is less the infection is likely to happen at that part. So the integrity of major blood vessels has to be maintained, I have already told you and it has to be based on the named vessel as I told you in the initial slides. So the fundamentals, the direct access to the target I have already noted. For example, if there is a convexity meningioma. So your flap should be such that it is directly centered on the meningioma. So it is all around. So it is not that the meningioma is eccentrically located and you are struggling with that. You need to have a wide accession for those tumors so that grade 1 surgical accession is obtained. And for skull based lesion flap has to be made to the as lower to the base as possible and the position should be such that the brain is retracted by the gravity itself with the minimum interaction and your surgical access is very good. And the number of borehole for the cosmetic region in younger patients, just one borehole is sometimes is enough and with the rest of the things you cannot make with the pneumatic drills. For elderly patients you should be very careful because the dura is a deterrent to the under surface of the calvarium. So the multiple boreholes are required and make sure that the dural tear does not happen because sometimes it is difficult to close the dura in elderly patient because of the dural tear and you are not getting the margins. So you have to be careful. So I will be just taking up the all important surgical flaps. The tyrannol approach, tyrannol approach is required for all the anterior circulation aneurysms, supracellar lesions especially in the pitchu trees and then there is a paracellar lesions. So these very versatile approach gives a very wide access. So the position is that the patient is supine with head turned around the 15 degree to the opposite side and the head is little extended at that lento-oxyptal joint so that the frontal lobe falls back. Again there is a minimal retraction. So the incision starts just behind the hairline and behind the stem starts and then goes behind the hairline and ends just above the zygoma for the tyrannols. So then you can retract the flap anteriorly and then you can make the borehole like I have taken it from one of the internet book. The thing is you need to make a borehole here. Just you have to take off the temporary muscle from this aspect, make a small borehole for young patient. This is enough and you can take off completely with the pneumatic drill. And after that this is the phenol ridge which you can nibble it out or drill it out so that there is a good exposure of the surgical base and then your dural exposure is this one. So then it is retracted back. Your silvin feature is completely exposed and the brain is already fallen back. The retraction is minimal that you are comfortable with your surgical procedure. This is the frontal craniotomy. I think many people, younger people they make mistake by making a frontal craniotomy. So either their skin and season is wrong or it is too small or it is too big. So the thing is that it has to be very, very appropriate. For example for most of the frontal glioma, you need not to mark a very big trauma flap. I have seen that younger people they tend to make a bigger flap. You lose time, you lose blood and your surgical time is more. So to prevent that your exposure should be adequate. So this is the frontal bone, this is the coronal suture. So this is the, for example, this is the hairline of the patient. Your incision starts just behind the hairline, a little across the midline you can go for the incision. So go behind it and you can go behind the coronal suture and just at the level of the superior temporal line. So you just have to stop it. So then you can reflect the frontal skin flap anteriorly. So again this is again a net picture. So you just have to make a one burble here. And second thing is that go anterior, immediately towards the midline and just on the lateral aspect of the midline you just go posteriorly and make a frontal flap. So according to the extension of the legion, your bone flap may be smaller or bigger. If you are the polar tumor, your flap is just this much is enough. If there is a bigger tumor, for example, glioma extending up to the coronal suture or moving behind, then just retract the scalp posteriorly and your craniotomy may be bigger. Bifrontal craniotomy. So bifrontal craniotomy is needed for most of the anterior skull-based legion like olfactory group meningiomas, then sometimes supracellular legions, large legions where you have to do the inter hemispheric approaches. So again the patient's position is such that is supine, head fixed in the 3-pin. It is extended at lento-occipital joints so that the frontal lobe tend to fall back. So bicarbonate and season is required. It starts from just above the zygoma going to the opposite side. Then you can retract the frontal flap anteriorly. So here the two important thing is that once you are retracting it anteriorly and the pericranium you are retracting anteriorly, so you will encounter the supra-tochlear and the supraorbital nerve here, tend not to damage that because many times you are using your bipolar, coterie or sometime you are retracting with the help of your periosteum elevators. You tend to damage these things because there is always a vein and artery here. So there is a bleeding here and you tend to coagulate there. So by coagulating the thing is you are going to damage the supraorbital nerve. So falling that the patient many times contain long-term dysesthesia, pain, numbness. So it does not have to do anything with the surgical out one but think his patient is not comfortable. He has anesthesia over the forehead. So be careful not to coagulate in this aspect and even if there is a bleeding you can just compress it or put some sort of flowable hemostate or gel form and try to manage with that only. And then there is how to make a flap. So because the bifrontal craniotomy is required for these tumors, so you need to have two burhole on the each side of the superior sagittal sinus. So one burhole on the terional point on the right and the left side. This you have to avoid it. So you never make a burhole in the midline. So what is the idea is that so that if it is made it will be always be visible. Never do that. So after that how to go about it because the sagittal sinus put your some disector there and dissect it off for the superior sagittal sinus from one side then from the opposite side then cut with the help of the B1 here. Then go around with the B1 till this burhole on the terion on the right side then on the left side and just touching the orbital roof you just have to make a cut. It should not be away from the superior orbital rim because if it is away then your retraction of the frontal lobe will be difficult. It has to be flush with the orbital roof. Make sure that your B1 foot plate is touching the orbital roof here. And stop here, come from this side, stop here. Your flap is now it is only attached with a very small ridge of bone. Then you can just break it off from this aspect. And after that most of the time superior sagittal sinus easily separates from that. You can separate with the help of a disector and then you can take it off. And the dural bleeding many times especially from the superior sagittal sinus there are small emissary veins. So you need not to worry either you with the very low coagulation you can coagulate them or put some gel form or flowable hemostat and wait for around 5-10 minutes and the bleeding is gone. Do not tend to coagulate too much here. This is a very typical flap. So this is the one piece flap of the frontal base for the transbezel approaches. So the two bar hole here and then with the help of your B1 I just have to go till the orbital roof margins and then you have to go to the orbital margins opposite side. And then with the help of oscillating saw or with the C1 point then make a cut on the nasion here then on the side of the lateral aspect of the nasal bridge on the each side and then once you have cut all around on the nasal cut is made then you just have to break it like that. So it usually breaks just at the level of nasal bridge. So the single piece is raised. You can see that it gives a very wide exposure. The anterior skull base is completely exposed. This is the superior sagittal sinus. The bleeding is controlled with the surgical and gel form and just wait for 5 minutes. It always stops. There is not at all a problem. Now you can see that if you are going to take out the ethmoid sinuses here. So you know that you are exposure till the even the sphenoid sinus you can go. You can go even up to the upper clivus. So it is a very wide exposure. Both side orbits are exposed. So for extensive anterior skull base lesion this is a very very versatile approach. And once you are done, you just put the flap back and you have already raised the pericardium flap. So you can reflect the pericardium flap down and with the help of fibrin sealants you can just even if there is a little bit of dural breach, you can easily close it. It seals off very well and the CSF leak is practically knell in these situations. This is a two piece flap. I already told you this is the one piece. This is the second piece. So once you have taken off all the anterior skull base lesions. So this is the sphenoid sinus, this aspect. So it gives a very wide exposure. So the temporal craniotomy. So temporal craniotomy is required for most of the temporal lobe tumors or avioms or sometimes you are requiring the temporal labectomy to go into the basilar artery, the basilar region for epilepsy surgery for the medial temporal sclerosis. Then these craniotomy is a versatile and you need to know it. So the what important aspect of patient is supine and the head turn to the opposite side. So thing is that the head is always rotated to the opposite side in such a way that these the zygoma is the highest point. The zygoma is highest point, the temporal rope is retracted back. For example, if the temporal lobe does not fall, the head is straight or little on the opposite side. So your surgical position ergonomics is not good. You are operating just like that. So all the time you are tired, your back will hurt and the patient is not at ease. So your surgical line of vision is not correct with the help of direct access or even with the microscope. If the head is tilted on the opposite side, so you are directly accessing the legion. So positioning is very important. So this is a question mark in season. So just at the superior temporal line and you go behind just at the level of pinna and go back and just at the level of zygomatic arch you stop. You just have to make a one burhole here, not multiple. So these are all the internet pictures. So one burhole here and you just have to go around with the help of your B1 and come back here and you can reach up to here. So small bridge of bone is left here with the help of your periosteal elevators or the bone elevators. You just have to break the bone and osteoplastic flap is made. Another aspect is reverse question mark. So where it is required? For example the tumor or the legion is on the posterior temporal. In the posterior temporal region if the tumor or whatever the legion is there. So what happens is that if the tumor is here you are making this question mark and your flap goes like this. So it means that this flap is purely based on the superior superficial temporal artery. So you are going here probably you may be cutting the posterior auricular artery here. So the posterior aspect of this flap will be ischemic. So if you are going to make just like that this part becomes ischemic and many times you will see that this is a little dark or a margin become black. So if your legion is posteriorly then you have to re-devise your flap. This is a better flap. So go like that this is based on the superficial temporal artery and the posterior temporal artery both are intact. So your surgical flap ischemia is not there. Another aspect smaller legions if you do not want to do that question mark and season this is again in season you can make the quadrangle flap. The flap is reflected down toward the base of the skull and you can do your surgery. Now this is a position see that the zygoma is the highest point okay you understand. So the zygoma should be higher so that the temporal lobe falls back with the gravity or with the minimum retraction. So this is the crinotomy just for the quadrangle flap. So the orbital frontal flap. So again the orbital frontal flap is this is in season just at the level of coronal suture. This is again an internet photo you do not have to make such a big flap. Just say the frontal flap which I have already told you just you have to reach up to the zygomatic arch and 1 centimeter interior to the pinna and triggers and going just below the zygomatic process. So the thing is that how to do about it. It can be made in two pieces or it can be made in one piece. So for the two piece what you have to do is make a burhole here then make a temporal crinotomy okay and it could be osteoplastic or it could be free bone flap. So make a temporal crinotomy once you are done with the temporal crinotomy. So you have already made a burhole here which is communicating also to the orbit okay. So this burhole is communicating to the orbit and the anterior crinotomy also. So another thing is that this crinotomy is done you have to make a osteotomy just lateral to the supraorbital foramina and then make a crinotomy here and second crinotomy just at the base of the zygoma okay. So second osteotomy here third osteotomy at the zygoma itself okay the maxillary process of the zygomatic bone okay. So you just have to make a this osteotomy here and another thing is that now the orbital roof is intact. The only thing is orbital roof is intact retract the orbital frat anteriorly you can make with the help of C1 osteotomy here or because already you have made a burhole here which is communicating with the orbit and again make a cut superiorly. So with the help of a ranger you just can break the rest of the bridge. So the two piece crinotomy is made. Another thing is that if you want to make a single piece crinotomy you can make a single piece crinotomy also. So that this is the terional burhole is made which is communicating with the orbit also. So second burhole you need to make here so that this is a free flap to crinotomy you have to make is that you have to take off the muscle the temporal bone. So start from here cut here and go around and reach up to the superior orbital margin you make a osteotomy here another osteotomy here and another osteotomy at this level okay this level and then with the help of your C1 or the osteotomy you need to disconnect till the superior orbital fissure here and then you have to cut the superior orbital roof from inside. So then you can break it off so it comes out as a single piece. So I think I can tell you from this thing. So you need to make a burhole here go around it here and reach here okay and then you have already communicated to the orbit here so this burhole is communicating. So you make a cut here you make a cut here okay you just put your B1 foot plate here it just easily makes a very nice cut till the orbit. So 1, 2 and third cut is here so that with the help of your C1 burhole is there already you cut the superior orbital roof here retract the orbit down and with the help of C1 make a little cut here so that is all you are done. So the one piece crinotomy you can make. So the combined temporal and sub temporal tumors so many of the temporal basal tumors like chondrosarcomas then many times sometimes infratemporal lesions going superiorly. So then you have to the combined approach this goes till the angle of the mandible okay this incision and then you have to expose the facial nerve here because that is the most important aspect. So this is many times may be injured you need to expose the facial nerve just at the angle here okay and you need to see the trunk and the fending out of into the parotid gland. Many times the perotectomy may be required and then you may have to do the excision of the rimmers and many times in the condyle may be required to excise. So these are the tumors then you have a direct access to the temporal base okay the reconstruction can be done later and this is the exposure for these tumors no doubt this is not a simple thing just for the matter of the mentioning I am saying so it requires lot of practice and your ENT colleague may be required for your skull base approaches. So another thing is that for minimal access surgery nowadays is very common this is supra orbital keyhole craniotomy so the patient is just in the frontal position like in most of the situation. So this keyhole approach is good for the anterior circulation aneurysms small tumors of the anterior skull base craniopharyngeomas and biopsies of the for example supra orbital lesion if required sometimes and supracellar epidromoids so this is also a very good approach for those lesions. So this thing is that patient is positioned with the head extended little back head is turned to the opposite side. So then season starts just lateral to the supra orbital foramen goes through the eyebrow goes laterally and it is not that posteriorly just around one centimeter lateral to the eyebrow. Okay after that you just have to retract with your help of the fish hook one thing the one aspect is retreat down and another is a retracted up or you can put up a small retractor but in the practice the fish hook is better because it does not take much of the space right and then you have to save the supra orbital nerve it has to be the lateral you try to preserve the supra orbital nerve otherwise the patient will have lot of anesthesia. So the rest of the procedure is more or less similar like you make a bar hole I think this is again a little lower down so your bar hole has to be just at the base at the t-reon it again communicate to the orbit here then with the help of your B1 it goes just lateral to the supra orbital foramen and another cut at the zygoma then with the help of your C1 because you are communicating already to the orbit cut the superior orbital roof and then you can break it off. So this gives a quite good exposure for the interior skull bays okay then once you open up your silver fishers is on the inferior aspect of this in season you can open it up to drain the CSF you can retract the frontal lobe and go ahead with your surgeries. Then another thing the surgeries across the sagittal sinus many time the surgeries in the inter-hemispheric fisher is required and to go to the fulcine tumors and also you need to have this craniotomy to go into the transkelozol approach to the lateral ventricular tumors. So this approach is required so another thing is that you can always have a bicarbonate in season not this is this in season is not a very because it's coming to the forehead bicarbonate in season is enough you can reflect it anteriorly to but whole here and to but whole here okay then you can connect it all around the same thing I already told how to control the bleeding of the sagittal sinus. So thing is then tumor is in the lateral ventricle for example the body or the frontal horn you retract you go to the inter hemispheric fisher now see that this gives a very wide exposure because if your craniotomy is not across the sinus so many times this is because the frontal lobe is difficult to retract you may have to go under it then retract back so it gives a lot of retraction to the frontal lobe. So if you are going across it then this becomes a very straight approach okay and second thing is that you can go to the opposite side just like that and it is a similar thing. So retromastered suboccipital craniotomy you all know how to position a patient so lateral position is or the part picking position is very commonly done for these patients and many times the sitting position is also preferred by a few of the surgeons so the position is individual and every position I would say is okay and you have to be tuned to a particular surgical position. So another thing is that for the trick of this surgery is that how to identify where is the transverse sinus because your surgery has to be below the transverse sinus should not be above or should not be too down then how to identify where is that transverse ison you need to identify the anion you need to identify the superior orbital zygomatic process so join the line to the zygomatic process to the anion so this line is actually on the transverse sinus okay so then you have to see the where is the mastoid tip so you just have to be around one finger behind the mastoid tip make an season laziously in season just like that so that in season is enough for the exposure your season need to go a little up and the lower part of the season should not be below the angle of the mandible the lower part is the angle of the mandible go posteriorly that is the enough okay so this is a standard in season as you grow senior in your career so the smaller in season may do okay so but for a standard approach this is the thing. Transpetrus pre-sigma approaches so these approaches are required for the clival lesions the tumors of the lesions sitting just anterior to the brainstem so this is the position okay park banks position is enough for that see the in season is quite extensive just like that it starts just the angle of the mandible here then go around it and temporal crinotomy is also needed in these patients because the combined approaches may be required so this is the root on surgical textbook picture so this is the dissection this is the junction of the transverse sinus and the sigmoid sinus okay so this is a crinotomy here okay and this petrus bone is drilled mastoid is drilled petrus bone is drilled completely so once the petrus bone is drilled so these are the semicircular canals here okay so this is the base of the temporal this is middle cranial fossa so this is the sigmoid sinus this is the transverse sinus and here this is the superior petrusal sinus okay so this thing now the dural opening is here so you have to start your dural opening from the temporal side basal side go across it so once you are opening it up this superior petrusal sinus you need to clip with the help of the ligar clips okay otherwise there are a lot of torrential beading many times this happens so another important point which you need to see is that vein of lebe also drains somewhere here so you need to protect it okay these two things are very important for the surgical exposure you need to divide the dura here and just anterior to the sigmoid sinus okay so now you see that your everything is is visible from your angle very wide exposure so this is a far later approach various skin flaps are mentioned so this is a hockey stitch in season most of the time this in season is enough you don't have to take it so down so you're in season ends here okay since the hockey stick and this is gives a very wide exposure you need to drill the C1 you need to expose the vertebral artery here so this is and you need to go up to the condyles okay occipital condyles you need to drill it and anteriorly and so that your anterior approach is there so that you don't have to retract the brain too much so midline suboccipital craniotomy so this is the position again you have to the head should be a little higher up and another thing is that you need to say that your jugulars are not pressed there should not be at least two finger breath space should be here at the chin and the neck and make sure your neck is not compressed too much so the standard craniotomy so just below the transfer sinuses you make a two bar hole here then connect it and go up to the rim of the foreman magnum so this is a infratentorial supra cerebellar approach that the cross approach so patient is in a sitting position the chances of air embolism and the hemodynamic instability is very high in these patients you monitor there has to be a center venous line place okay it has to be in the right atrium then there is a trans esophageal echocardiography so this is the T that is trans esophageal echocardiography so that you are monitoring just behind the heart direct into the right lateral ventricle and the atrium the movement that even the speck of air goes it detects so that it is very common to have air embolism in sitting position many time it is asymptomatic but even if it is happening at the very early stage you need to detect it okay and this is the position again so make sure that the tentorium is parallel to the floor okay so try to draw a tentorium in a particular patient and try to bring it parallel to the floor so this is the key to the surgical procedure so once you have done cerebellum falls down with the gravity and you can reach to the these tumors so this is a occipital trans tentorial approach so you are going from the same side the same side is always dependent if you are going from left side so left side is dependent so that the gravity leads to the fall of the occipital load to the opposite side this is in season so this is the craniotomy okay this is a craniotomy so and you go into inter hemispheric future you have to divide the tentorium and go to the this final region so this is a little one slide for the laminoplasties so thing is that I would just like to make few words and comments so thing is laminoplasty you all must be doing it but thing is it has to be very very tricky situation in many situation because with the help of the drills which you are using so the surgery may not harm but your exposure sometime lead to the harm to the patient so if you are putting up because already the cervical canal is compromised into the degenerative spinal spinal losses many time OPLL is there and the canal is very narrowed and compromised and if you are trying to put your B1 foot place down and taking it off so thing is your B1 is going to harm and the hit the cord and the patient is having a very bad neurological outcome so make sure that you are not doing it especially in a compromised class use the help of your amate or the bar you make a gutter on the each side and then you have to break it up okay so you don't have to put your foot plate down and nowadays in the bone q size available and it gives a very nice small cut okay so with the help of that you can make a very nice cut on each side and you can take off this whole laminoplasty flap in one go so these are the very few suggestions and this can definitely improve the outcome on a particular patient thank you