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Grand Rounds-Pterional Craniotomy: Details of Technique

Troy Payner

September 18, 2015

Transcript

- Hello, ladies and gentlemen, and thank you for joining us. The discussion today will be regarding, Technical Nuances for performance of a Pterional Craniotomy. We have one of our special guests back, Dr. Troy Payner. A dear friend, and the president of Goodman Campbell Brain and Spine. And he'll be taking us through this approach, which is a workhorse of cranial procedures. He has extensive experience with cranial approaches, and I personally really enjoyed, watching him do this procedure, and therefore, I'm happy to have him with us today, discussing this approach. Troy, thanks again.

- Well, thanks for having me.

- Let's go ahead and briefly review disclosures, none of which interferes with the presentation today. So Pterional craniotomy, as we know, Troy, it's a workhorse approach. It's probably the most common skull base approach that we use, because it's so flexible, it's easy to perform, it is familiar to neurosurgeons, and really exposes a large area of the Parasellar space. It's expandable. You can have the supraorbital osteotomy, or an extended frontal bony removal, and also remove additional bone, on the skull base to approach many lesions again, in the parasellar area. And provides really a generous number of working angles, at the skull base. Now, what else do you think really this approach provides, that really defines it.

- Well, I'm glad that first thing you said is, you described the Pterional craniotomy, as a skull based approach. And I'm glad to hear you say that, because, when skull base... the concept of skull base surgery, was first developed, it was thought of as everyone knows, how to do Pterional craniotomy, but to make it a skull base approach, you had to add something to it. I hope today we can convey the message, that what has always been thought of, as a standard Pterional craniotomy, really can be a skull based approach. Sure. You can add an orbitozygomatic approach to it, and drill off the clinoid and other things, but just in itself, if you think of the Pteronial craniotomy, as a skull base approach, based on the principle, that you are going to maximize bone removal, to minimize brain retraction, then you will be very successful in using this approach.

- Thank you. And also this approach, really enables the generous exposure, of the frontotemporoparietal operculum. You can open the sylvian fissure widely, and really gives you access to insular, a lot of different tumors in this region, although rare, and really it's a generous operative corridor, to the cisterns and the basal cisterns, to different vascular lesions, from anterior communicating artery aneurysm, to a superior cerebellar artery aneurysm, and really at the light of meningiomas and tumor, in this area. What are the other unusual lesions, we approached through these sort of corridor, that you would say people have under utilized? Do you have any thoughts there, Troy?

- Well, I think, you know, you described this as a workhorse, and the reason is because it can be used, to approach so many different areas. So you can get something on the most anterior skull base, all the way back to the posterior fossa, as you mentioned. The upper basal area. You can approach suprasellar lesions. You can approach lesions, that protrude into the third ventricle, by opening the lamina terminalis, and then you can follow the sylvian fissure out distally, and approach lesions. There is an extremely versatile exposure, and there's not a limited number of pathologies, that can be treated through this approach.

- Right. You know, we often become very trendy in neurosurgery, and feel like skull base approaches, you know, are much better, but this approach really has stood the test of time, and just removing more bone, and trying to have a very extended craniotomy, doesn't necessarily mean it's better for the patient. Obviously--

- Well, I wish to say something.

- Go ahead.

- Sorry to interrupt. I hope today I can make the point, that if you are compulsive, in the way you perform your Pteronial craniotomy, it really is a skull base approach.

- I totally agree with you. As they say, or as I believe personally is, it's not about how you get there always, as we spend so much time in neurosurgery arguing, it's about what to do when you get there, and how you handle the lesion. And sometimes using a very basic approach, to preserve your energy, during microsurgical part of the operation, can be very important. As you know, doing a very large skull base approach, can take part of the day, and when the surgeon arrives, to the most important part of the operation, especially the large lesion, it can become challenging, and somewhat the surgeon can not be, as ready and enabled. So before we go to your case, I would like to show some slides. This is how I have done it. Doesn't mean it's the right way to do it. I'm just gonna provide a different perspective, and obviously, I'll very much like to hear your thoughts here. The patient is positioned supine. If the patient is on the older side and heavyset, obviously we really would like, to place a gel role, you know they're not to turn the neck too much, or put it in a non-physiological position. Placement of the pins, I think it's a matter of opinion. I like putting one behind the ear, and the other two on the superior temporal line. That moves most of the larger arm with a heavy, lock her arm out of my way, and just one pin behind the ear. Ample amount of space to work. The incision, obviously I use behind the hairline, and I'll make sure that, if you connect the inferior edge of incision, to the superior edge, that line from here to here, is about a centimeter, from the keyhole. That allows you to reflect your flap adequately, to expose the keyhole, which is so important. I know you use the more of a curvilinear incision, and you now review the advantage of that momentarily. For me this is advantageous, because it really leaves the least amount of scalp, between the keyhole and the incision. Any thoughts you have there, Troy?

- So obviously, you know that I put the pins in differently, and we have a slide later to show that. The main reason that I put the pins in differently, only has to do with the retractor system that I use, so that I can clamp onto both sides of the Mayfield. So I'll put two pins back here, and my one pin over here, and then my Halo retractor, can encircle right over where my craniotomy is. You'll see a picture of that coming up. The second thing is as you've mentioned, your incision curves toward the other side, and that works fine. My concept of it is, if you think about where your incision starts, which is basically at the root of the zygoma, and where it ends, and if you were to draw a straight line across that, you have to be able to pull that forward, to get to the keyhole. And that's the reason, again, it's just somewhat surgeon preference, but in my experience, curving this incision forward right here, and stopping just at the hairline. Now, obviously if they have a receding hairline, you're not gonna be able to stay behind it, regardless of how you make this incision, but a person with a normal hairline, as this curves forward, at least in my opinion, my incision would end about here. And then that straight line is, gonna be a little bit anterior, to where this straight line is. And I think it just, the more anterior you get, your skin, everyone's, every patient's skin will stretch somewhat, but your ultimate goal is to be able, to turn that flap, to expose the keyhole, which we'll see shortly.

- Thank you. Again, this is how it's placed in real life in surgery. And obviously the malar eminence is the highest point, to allow the frontal lobe to fall away, and minimize that retraction, depending on where the lesion is, the head is turned differently. The more closer the lesion is to the midline, such as an anterior communicating artery aneurysm, or a parasellar meningioma, the less turn of the head you need, to approach the lesion. The more away it is such as an MCA aneurysm, the more turn of the head you require.

- So what I would say on that slide, you want to go back one, but I agree with your positioning. So I think of it in terms of three steps, one is to, lift the entire head up, so that they're extending their neck forward, then extend the neck, and then rotate. And that brings the malar eminence, to the highest point, but it also brings the area, that you want to approach, the pterional area, right up, in most easily accessible position. You don't want a situation, where the head is kind of down below the table. You want it up in front. You want their neck somewhat forward, rotated, and extended. And I think of it exactly in those three movements. Lifting the head up, then rotate, and then extend. And then that maximizes your optimal exposure here.

- Great points. Thank you. We tried to put the incision, behind the superficial temporal artery, to preserve the vascularity to the scalp. It's really relatively straightforward. I use a sidla dissector, just where the scalp is covering the temporalis, to protect it right and cut through both, and then use sharp on blunt dissection, to protect the anterior branch, of the superficial temporal artery. Any a nuance to this there, Troy?

- So I have no problem with this. I just do it a little differently. I'm not saying there's right or wrong. So I'm a man of very few instruments. So I have an assistant, holding pressure with their hand, on each side of the incision. I'm holding one side, the assistant is holding the other, the assistant holds a suction. I hold the knife. Or I'm assisting, and they're holding the knife. But in any regard, I don't put an instrument underneath. I use my knife blade sharply, and I open the galea, and preserve the STA. And I try to emphasize when training residents, that they should be able to save the STA every time. It's a good way to build your skills, and sensing how a knife blade cuts, and how you can cut the galea right over the STA, without actually cutting the artery. And it takes some practice, but it's a good way to learn, some gentle technique, dealing with avascular structure, particularly in a situation, where it may not be vital, if you lose that vessel. It's a good opportunity to learn.

- Often I usually elevate this temporal fossa, with the scalp. I think you do it a little bit differently. We're going to review that, but there's nothing wrong with elevated. I put one burr hole below the superior temporal line. I don't use another hole here, because it minimizes the bone loss, and potentially decreases, the cosmetic deformity and depression, after pteronial craniotomy. And then this also allows you, to use the dissector all the way around, and sweep and detach that dura from the inner skull then I just go around, turn the drill. And I know we momentarily are gonna review yours. So if you don't mind, if you want to... Yeah, go ahead.

- I think this works fine, as you'll see, there's many ways to skin a cat, right. So my burr hole is placed here. I don't place it right up under the keyhole. I place it under the muscle, a little bit lower, so that the muscle will cover it at the end. And unless the patient has a very thin temporalis, to begin with, I really have not had a major problem, with an indentation here. If they have a very thin temporalis muscle, then I think that risk is increased, almost no matter what you do. Unless you can fill it in, with some bone substitute, or plate, or something at the end, to keep it from sinking. But my experience suggests, that the most common place, to tear the dura with a drill, is coming across the frontal floor. And that's why I like to put a burr hole here, and then with my dissector of Penfield 3, I can sweep it underneath here, all the way over, across the frontal floor, and then I make sure when I drill there, that I'm not gonna cut that, or tear that dura. And you'll see that in the video. But again, there's more than one way to do this.

- Thank you. This is something that I've learned from you, Troy. Really a great technique. After the bone is elevated, you could sit the dura off, and you really generously drill this area, because this is the operative corridor. I mean, this is really essentially, superior frontal lateral approach. And you've gotta get them dura off. You got to drill it down. I know you're gonna show that to our video, and you're gonna drill the pterion. And that's what makes it a skull base approach. Could you please comment on that?

- Well, you took the words out of my mouth. This is where this becomes a skull base approach. This is where you can maximize your bony removal, to minimize your retraction. And the question I like to ask people is, if you're drilling down the pterion, how do you know when you're finished? And the answer is not, "Well, when it looks flat." I mean, there are landmarks, and we'll see those in the video, that you should be looking for, to make sure that you have maximized, the amount of bone, that you can remove, with the ultimate goal, to be a completely flat straight line, under the frontal lobe, straight down to the optic cistern. So the sphenoid wing is on a curve. You've all seen that curve on the skull, but if you drill all the way down, to the superior orbital fissure, and literally remove all of the bone, over the superior orbital fissure, is farther down than this picture shows. From the superior orbital fissure, to the tip of the clinoid, which is the most medial point of the sphenoid wing, it's a straight line. The curve stops. So the primary curve is out here, and that's what you're getting rid of. And when you get from the superior orbital fissure, to the tip of the clinoid, or to the optic cistern, there's no more curve. So you can place a retractor in... almost no matter how tight your brain is, you can place a retractor blade, right on the floor of the skull base, without having undermine any bone. And you can go straight down to the optic cistern, and to release CSF to get relaxation. And we'll see that a lot more, coming up here in the pictures and the video. The second point I will make is, that I do strip this off aggressively. And when you take your Leksell here, I always take a bite off the temporal side first. The bone is then easier, to take this bite that the drawing shows right here, because it allows you to get one side of your Rongeur, on the temporal side without this ball being in your way, because you've bitten this off first. I think we'll see that coming up as well.

- Thank you. Go ahead, Troy, please comment on this one.

- Here you're doing just what we talked about. So I generally do this the same way every time. You could cater somewhat and say, "Well, I'm gonna drill the orbital roof flat, "for only ACM aneurysms, "or suprasellar lesions," but you don't want these spicules, and prominence is sticking up on the frontal floor, if you're going to put a retractor blade down, to the optic cistern. You want this to be absolutely flat, and you're basically drilling all of the bone, right around the orbit, and you can get down right to the cortical bone, of the orbit, all the way around. You don't have to drill the bone off completely, but you can drill, leave the orbit cover just with core orbital bone, cortical orbital bone. And down to superior orbital fissure, and then take some of the temporal bone, and you will have a beautiful skull based exposure.

- And that almost minimizes, the use of orbitozygomatic craniotomy, because you are so low, that you really then need to use that approach, for select cases, don't you, Troy?

- Right. So the only thing you have to be aware of is, you don't want to drill out here, because then it's going to be cosmetically evident. And if your craniotomy is not low enough, then you're not gonna be able to do this. So that's another reason, I make my burr hole down here, to make sure I'm coming as low as possible here, so that I can get, and we'll see that later, but so I can get underneath the frontal lobe. If I need to come from a little more medial approach. If you have a rim of bone here, that is cosmetic or right on the surface, you're not going to be able to drill that all the way down, or you're gonna have a big defect at the end. So the key is that your initial craniotomy has to be low enough so that you can then undermine the rest of it, to get rid of all this bone, to make it a true skull base exposure.

- Thank you. The dura opening is pretty standard. Don't you agree?

- Yeah, I think that you've made these, you know, the craniotomy you're going to see in the video, is a little larger than this one. And I don't think you need, to expose the brain, for your entire craniotomy. Although this is obviously a smaller craniotomy, so that you using all of your exposure. But I don't think the morbidity, of a slightly bigger craniotomy is any higher. The size of the craniotomy is not the determining factor, in the morbidity here.

- Right. But as we know, this is mostly a really a soft funnel approach.

- Correct.

- So you don't really need as much exposure, of the temporal lobe, and some people may expose more than necessary. So you don't have to remember, this is soft funnel. This is not a transtemporal approach, and really extended exposure, of the temporal lobe is not necessary. And I think opening the fissure starting, you know, from distal to proximal, proximal to distal, bridging vein, I think those are pretty standard. This is not, I guess, session for Sylvian fissure dissection. But if you have any thoughts set to add, before we go to your case, could you please add here, Troy?

- So on the previous slide, I don't know if you can go back, but I agree this is not a temporal exposure, as you say, but look, I would have it... I would like, as you've drawn, to have at least this much temporal lobe exposed, and the bone will be drilled. When I do it virtually all the way to the temporal tip. And that particularly is helpful for me, if I'm clipping an ACM aneurysm, because I'm coming from lateral looking almost up at it, from way lateral. I'm not coming so much anterior for an ACM. I'm following the course of the A1 across to it, and looking from low and up, toward the ACM. So I do, particularly in that case, anything suprasellar, I do like to have adequate temporal exposure.

- Thank you. This is a patient of yours, 47-year old male, or actually this may be really pictures, of a different patient, but the video is essentially approaching a very same lesion. So 47-year old patient with bilateral visual dysfunction, was noted to have a large craniopharyngioma, and also frontal symptoms. And I think we'll go ahead, and review the positioning for the patient. Can you please take us through this, Troy?

- So again, this is not about right or wrong. This is just another way to do it compared to the drawing. So I prefer from the root of the zygoma, to make more of a C-shaped curve line like this, rather than the alternative of bringing it, across over to the other side. And I think you can just get this a little lower here, so that this line is closer to the keyhole, which is here, and my line crosses here. So you don't have very much to pull the skin down, to get to that key hole. It just has worked for me. And this is a hair sparing approach. You don't necessarily need the strip to be this wide. You could make it a little narrower, but even preserving this much hair, at the end of the procedure, the patient will be able to cover this completely. And really no one's going to be able to see this. You can see the position of the pins. As I said, one hole off to the opposite side, as far lateral as you can make it, without sliding off the edge. Two pins right in the back in the middle. And again, the purpose is only because I use the Budde Halo retractor, or the Dora retractor, and the clamps go on each side of here, and the ring is going to be centered on my craniotomy.

- Thank you, Troy. I think this is another view from the lateral side. interesting.

- The only other point I'll make here, and I guess I told you the three steps, lift the head up, extend it, and rotate it. The other thing you'll see slightly here is that. I tilt it slightly, to open the angle between the shoulder and the head. You don't want this tilted toward that shoulder, you're gonna be cramped in your working space. And so there's a little bit of tilt at the end, just to get a little wider working space right here. And it gives room for an assistant, to be on your right side, to help you during the surgery, if you need it.

- Thank you. Let's go ahead to video now, and review the details, of one of your patient's video. Thank you, Troy. So Troy, let's go ahead and review this right funnel, pterional craniotomy, and please take us through the details.

- [Troy] Okay. So we can see, and I'll start the video. Let me qualify this by saying, that this is the way I do it. I am not claiming that this is the only way to do it. It works for me. And there are several important points about this. As you will see, when I go through this, I do a pteronial craniotomy in a stepwise fashion, and I use the same instruments, in the same order, every time. It is very consistent. And when you do that, your scrub nurse is gonna be much better at helping you, because she's going to know exactly, the order and routine of the instruments. And you were gonna get to a point, that you can do this very quickly, and save your time and energy, for clipping the aneurysm, or taking out the tumor, or whatever you're targeting. So very compulsive about this. First step, we talked about minimal hair shaving. Watch how many staples I'm putting in here. I do not want hair, getting into my wound here. So I'm going to staple this, go a bit overboard. I put one towel here and again, I'm very compulsive. I do it the same way every time. Right to a T here. and then I just, I have the towel on incision, pull it back with the hair, and keep it there. I remember I have the front of Mayfield clamp here, and I'm stapling that out of the way. So it's draped out of the field. That's two towels, and there's going to be a third towel. And again, compulsively keeping the hair out of the field. There's nothing worse at the end of a case, when you're closing, and you're pulling all these hairs out of the wound, you're gonna get infections. Give yourself enough room. Again, this is subtle, but at the end, leave yourself a wide enough space here, to staple the incision closed, without stapling the towel into the skin incision. So we'll see that at the end. I referred earlier, the assistant has the suction, and spreading the fingers, and holding pressure, not so much pulling back, but pushing down. And when you do that, there's minimal bleeding. And you see here, that we can make a smooth cut. And I talked about saving the STA, and there I've opened the galea, and there's the STA, I can see it, and I can cut right down on it, without cutting it. Keep pressure on the edge of the incision already. I use my rainy clips as a reinforcement, to hold that towel, to the scalp. Keep the hair out of the wound there. I opened the temporalis muscle with a knife, I would have preferred not to do that. So the rainy clips, you see, some people put them very flushed together. I have no problem leaving a little space between them. I've made one cut coming up to here, and I'll make my second cut, from the beginning. My fingers can spread that length all the way to bone. This part is not over the temporalis muscle. You wanna be as perpendicular. That was sloppy right there. Criticizing myself. I should not have that little flap of skin there. It should have been straighter. But you wanna connect to those two incisions, or you connect to that line to open this flap, and then put your rainy clips the same way. But you see, we made one cut coming up, and one cut connecting it, as wide as our fingers can spread. That covers the length of the incision, that we can open at a time. If you do this, there's really very minimal bleeding. I like to raise this flap in two layers, and I use a scalpel, to make sure I stay in an avascular plane. I'm not burning anything, so I don't use the Bovie for this. And it's a sweep. I always use the blade, belly of the blade toward me , and I come right down there, to the root of the zygoma. And I focus on the frontal side up here. I undermine that right there. See, undermine right there to get down to the keyhole. The fat pad we talked about is down here. You don't need to dissect so much, because your temporalis muscle, is going to come up with this flap, stay out of that fat pad. Right here, my thumb, I'm feeling the keyhole, I know I'm anterior enough. I put a rolled sponge behind the flap, and I use fish hook. It's the same way every time. My first fish hook goes right at the keyhole. And then I'm gonna put a second fish hook, on the frontal side. Once we get that fish hook there, then I'm not gonna put a fish hook right here, because it's a wasted step. I'm gonna open the temporalis muscle reflected over here, and then I'm gonna retract both with one fish hook. I don't need a fish hook here yet. So now I've got two fish hooks. I use a Bovie. I come through this, I open the temporalis fascia. I don't go all the way to bone right here, because I don't like bleeding. So I go through it in two layers. I go open the temporalis fascia. Here I go to bone opening the periosteum. Here I'm staying very low, frontal, as low as possible. Now I'm gonna come through here. There's commonly a vein, that you'll get into right here, but if you're careful, you can save it, or at least coagulate it. I don't mean save it, but you can coagulate it without getting bleeding started. Feel the keyhole. I'm on the orbital rim of the keyhole, and drop into it. I see right here, this is my target. 'Cause I've already opened. I know where I want to leave that cuff, and I'm going to open right there. Now I have a nice cuff of muscle, to sew back to at the end. My assistant lifts this up. I use a suction to also, not only to suction, but to help with the retraction where I need it. And I elevate this right up. Any comments, Aaron?

- [Aaron] One thing I would like to add is, I like the way you're doing it. Just to be very aware, that you cannot go too anterior with this incision, or a cut here in order to avoid the frontalis nerve. Obviously you're posterior to that, if you have to leave a cuff with this one, to leave more of the fat pad, that's reasonable. But I think as long as you don't go all the way, to protect the frontalis nerve. I think that's maybe one you're less.

- [Troy] Thank you. And again, feel free to make any comments you want during this. I take this all the way forward to the keyhole, and you can even take this down a bit, and now watch this. I'm gonna leave, cutting this way, I left a little cuff right here. I have temporalis fascia, and temporalis. I'm gonna take these three flaps at the end, with a stitch to close, because my burr hole is gonna be here. And I'm gonna be able to cover that, with some substantial tissue here, to keep from getting the atrophy. I next put my fish hooks on the temporalis muscle. And after I put my one or two fish hooks, on the temporalis muscle, I will get the Bovie back, and take this even lower. I do this as I say, exactly the same every time. That Bovie, the nurse just handed it to me, 'cause she knew it was coming next. Notice that I'm opening with my left hand. When I get under the microscope, I switch to right-hand, just the way I've learned to do it. We tie a Curlex to the foot of the bed, to put these fish hooks on, so you can get excellent traction on them, to hold that temporalis back, so. Here's our keyhole. I really want this muscle back as much as possible. If I need to look over the edge here, from lateral side, I don't want a big bulk of muscle in my way. I'm less concerned back here. I'm really concerned more anteriorly.

- [Aaron] Right. Putting those fish hooks right where the keyhole is, where the operative corridor is going to be, is gonna be the key. And I think as you said, Troy, the fish hooks really work the best in this area.

- [Troy] So you see, there's been very little, if any, bleeding. And here I'm just defining, because I wanna make sure, that this is low. If I'd make my craniotomy and come back here, then I can get some frontal toward the medial side. I can get some frontal maybe right here, but I'm gonna be limited. So I'm gonna make sure I have this exposure. Now, do I need to come way over here toward the midline? No. But I will make this flat, and then I'll start coming across around here. So first, we're gonna make the burr hole down here. You can use a perforator. I've got used to using an acorn. Now you can use, make a hole and then you can get a Kerrison punch, and make it bigger. To me, that's a wasted step. I go, right. I make the hole big enough, with the drill, to get my dental dissector under there, to free up the dura. After the dental dissector, I take a Penfield 3, and I'm gonna to slide it all the way under here. This is where, in my opinion, the dura is most likely to be cut. Is when you come up over the frontal lobe here. So I take this 3, I make sure it's curved up under the bone, to really free the dura. And I'm gonna slide it across, and see I've freed up all this frontal dura here, and make sure you can't get very far down here, but I get a little bit of that freed up, toward sphenoid wing. And I will take the foot plate, and swing it right around. Now that subtle point with the drill, look, I like to lean it way back. Not forward. I'm using the toe of the foot plate up against the bone, and the heel of the foot plate is against the dura. And so the heel is pushing dura back, and the toe is against the bone, and it just goes right around. There's very little jiggle factor with it. I like just to make a smooth cut all the way around. Now, I haven't made another burr hole, so I just twist this a little bit, and it'll pop right out.

- [Aaron] And it's best to stay as low as you can. And as anterior as you can, so you don't have to drill more bone later, shouldn't we Troy?

- [Troy] Yes. So the lower you get, the more temporal exposure, and then you connect from here to there, across the sphenoid wing, and then you pop it out. So let's see how we did save in the dura.

- [Aaron] Looks very well.

- [Troy] It looks like pretty good. You're always gonna get your middlemen in GL somewhere. Not always, but frequently. So that you just coagulate it. Here, I am stripping the dura. Extradurally off the frontal floor and the temporal faucet. We're very low on the temporal. I don't think we're going to need more bone down here. I like this technique of putting suctions, as gentle retraction on the dura, because it serves two purposes. Remember I said earlier, take the Leksell and bite the temporal side first, so that you can get that side of your blade, to bite off the sphenoid wing. It's a big help, if you take this bite first.

- [Aaron] I think it's important, to use their Rongeur, because it's so efficient. It moves you along pretty quickly. And I think at this juncture, using a drill may just slow you down. Don't you think?

- [Troy] To a degree, but here I switched to the drill, and you'll see that, couple of points. Always, always few things are really always, this is one of them. Always have your suction deeper than your drill, because your suction is protecting the dura back here, and you don't wanna drill right on the dura obviously, but this particular bit is a side cutting bit. So even if the tip of it touches the dura, it won't cut it. As long as you're perpendicular to the dura, and don't use the side of the bit against the dura. So I'm sorry, you can't this real well, but this is the superficial edge of the bone. I will undermine the inner edge of the bone, and you can see, that we are flushed right on the frontal faucet floor here. And you can see already, the superior orbital fissure. You're gonna see it even better here in a minute. This bone all has to come off of here. It's going to be smooth cortical bone around the orbit, like we talked about. Even if you get into periorbita a little bit, it's not a huge deal. Notice I haven't used the Bipolar, and I haven't used bone wax yet. I'm gonna wait until the end. There's no point in stopping, unless there's really significant bleeding, until you get your drilling done, and then get all your hemostasis. So here I'm gonna probably get a Pen 1, and there it is, make sure what's left, what's left at the sphenoid wing. And I've got to expose better, down to get the superior orbital fissure exposed.

- [Aaron] Troy, you're very efficient. Video, no really editing done. Efficient technique.

- [Troy] So what I'm thinking, when I'm drilling this is, that I'm gonna open my dura here, and whatever is sticking out bone wise, is gonna be in my way. Right here, because I'm gonna flip the dura, over this spicule right here, and when I try to get my retractor down in there, that's going to be in my way and aggravating me. So I'm gonna drill it, until I've got superior orbital fissure open. And then I know, from that point down, it's a straight shot, and it's not gonna be in my way. So you've seen, that as much as I've drilled right next to dura, with this bit, you just don't tear the dura, unless you really put the side of that bit, right up against the dura, which you're just not gonna do. All right. So my hand was in the way, but there I've just used the drill as a dissector. That's another saved step, by not switching instruments. We're getting down the cortical bone. There's a little piece of periorbital, right at superior orbital fissure. See how the brain's nice and relaxed here. Then I put my bone wax.

- [Aaron] Again, that low trajectory is really the key, because that's where all your operative corridor is. This is really a lateral sub funnel approach.

- [Troy] That's right.

- [Aaron] And sometimes you get bleeding from the epidural sutures.

- [Troy] Here's the first time we use the Bipolar. And there's periorbita, right. The lateral part is superior orbital fissure. All the bone has been removed, over the superior orbital fissure. Here's tack up sutures, particularly if the brain's very relaxed. And we know when we drain the CSF, that it's gonna be relaxed even more. And that's a good indication, to put in some tack up sutures. I like to do it first if I can, save you time at the end.

- [Aaron] Honestly, do you wanna put these two anteriorly close, to the frontal side?

- [Troy] No. The frontal side is gonna be up here, hopefully medial to where we are, but. And you want these as close to the bone edge as possible. You don't want them out here, 'cause that's just gonna tighten up your dura here, and make it harder to close at the end. So here is a little clumsy with the tack up suture. See if we can get it. There you go.

- [Aaron] I don't know if there is anything clumsy, about this video Troy, looks awesome.

- [Troy] Alright. So to give you a perspective, from the time we cut skin, to the time we're opening dura, I'd like to say, from skin to scope, I think realistically it should be done in 20 minutes. With residents, You know, they start out, sometimes it's 45 minutes. And after they do it, with this technique a few times, they are much faster. And the key is that it's so consistent, and the steps are exactly the same every time. And there's a minimum number of instruments. You're not constantly changing instruments, which slows you down, because your scrub nurse never knows, what you want next. And then she has to find it each time you ask for it. So if you establish a routine, doesn't have to be my routine, but you just establish a routine, minimize your instruments, and just keep moving forward with this. You know, I like to say this, the way we do the pteronial craniotomy, is different every time. I'm sorry. It's the same every time. What's different is the pathology inside. So every aneurysm may be a little different, but the exposure is the same. And that's why you can make up time, during the opening and closing, and take your time and spend your effort, treating the actual pathology.

- [Aaron] Yeah. Getting quickly focused on the pathology. Spend most of your energy on the pathology, and get out quickly. Make the intradural microdissection, the most important part of your operation. Not the exposure. We're still less than 15 minutes, and we're ready to open the dura. So this is really an idea of timing.

- [Troy] It looks like, I've got a little split thickness on the dura, but I'm willing to accept that.

- [Aaron] Sometimes you get bleeding, from there underneath the temporal bone. And that can be very well managed with gel foam powder, as you can see right here. Often there is some bleeding, and you gotta be very careful. You may use a Bipolar, but that usually shrinks the dura away, and increases venous bleeding. So you may want to pack some gel foam, but obviously not too aggressively, to increase the formation, or chance of formation or epidural hematoma.

- [Troy] So what you'll see, again, it's surgeon preference. I'm not saying it's the right way. I choose to use FIBRILLAR SURGICEL, and I have the nurse roll it into little... Well, you'll see them here, a little to blitz or whatever you want to call them. And I just lined the epidural space with them. And I find that it works very well for hemostasis. And then put Cottonoids over them. So there they are now. So that's FIBRILLAR SURGICEL. That's dissolvable. You don't have to take it out at the end.

- [Aaron] Thank you, Troy.

- [Troy] I find it works very well. Now notice, I didn't put it down here, and I don't like to put anything down here, because that's just going to be a bump in my way, when we opened this dura. This is all about maximal volume removal, minimal brain retraction. So there's no FIBRILLAR SURGICEL down here. This is where I want my absolute hemostasis, without using any extra material.

- [Aaron] I think those Cottonoids work very well, to soak the blood, and keep your intradural work very dry.

- [Troy] What blood?

- [Aaron] That's true. Your surgeries are bloodless.

- [Troy] So if there's bleeding, you know, we'll take a look. 'Cause once it starts, there's powder. I'm putting powder in the tack up suture hole. Yeah. Blood starts oozing in your field, while you're operating from extradural. It's miserable.

- [Aaron] And it's frustrating.

- [Troy] So the other thing, that's going to stop any bleeding here is tacking this up. So notice the dura is relaxed enough. I could pick it up with my Adson, and use the scissors to open. And I'm gonna bring this across the fissure. And I open this a little wider, because I like to be able, to keep retraction across this space, so that I don't get epidural blood. and the other, this is a subtle point, but it's really beneficial. When you put this tack up here, think about where you want this piece of the dura to go. Because if you sew it over here, you're gonna pull the dura in the wrong direction. I really want the dura flat on the frontal floor. So it appears that I pulled this a little to the right, but you're gonna see that it's going to make it, so that the dura here, is as flat as possible with few wrinkles in it. Sometimes I'll just hold the dura up, to see where I want it to go. And then put my tack up, tack it back to that appropriate spot. So now you see how flat I've made this. There's a little wrinkle there. Prefer to get it as flat as possible. And then we'll take this one, and tuck it back over there. The other nice thing though, is when we get this tacked up, that also helps to stop any bleeding, that may be coming from behind it. And this one you notice, I put way back here, it's just a way to stretch this dura out, and get good tension on it. To minimize the epidural bleeding.

- [Aaron] I think that's a very nice nuance, to get those dura wrinkles out of your way.

- [Troy] Yeah. This is a little, I'll see if I'm going to do it here before I say.

- [Aaron] Yes, you can tack the stitches with it, mosquito or suture it either way to the muscle.

- [Troy] Yeah, I think personally, I just get a little tighter traction, with tying it back on.

- [Aaron] I got you.

- [Troy] Sometimes I will. And I don't know if I'll do it here, but sometimes I will take a stitch, and tack this temporal lobe back, temporal dura back over to the muscle. And that way, if there's any pooling of blood, I've created a little ledge here, to delay it dripping into my field. This one of course is dry. I put a wet sponge over the flap, and then I put towels around before we go, intradural here.

- [Aaron] The dura opening is smaller, and you use the dura to protect the brain, essentially from the heat of the microscope. And we don't realize how much, that heat can cause injury, unless you put your finger, for a few minutes under the light of the microscope. So I think it's really critical, to cover as much of the brain that you're not using, for your dissection away, from the light of the microscope.

- [Troy] I agree entirely. The other thing is, make sure you staple this towel back. If you're trying, to get real low on the frontal faucet floor, and this towel is in your way, it's just gonna drive you crazy. So make sure you staple it back out of your way. You don't wanna admit it, do all this work, and then cover it up with a towel. Doesn't make sense. But here's the point we've drilled. And this is a straight shot, right down to the optic cistern. And that is the optic nerve right there. And this is flat. So this is where we stop drilling, it's superior orbital fissure. And from that point, to the clinoid, right here, is gonna be flat. So this requires very minimal, if any retraction. There's the olfactory nerve, and you can put a retractor blade. I know some people don't want to use retraction, but can use your suction, to pull this frontal lobe back, and you can open that cistern, and you're right down on the optic nerve.

- [Aaron] And I don't think you're retracting. You're just holding the brain, it seems like, Troy, and protecting it for the instruments going in and out. Because the bony removal, gives you such a beautiful front, you know, inferior to superior working angle. Here's the optic nerve, obviously. We're gonna show, some of the early stages of Troy's video, showing how he does his auricular dissection. I really like his technique. He uses mainly micro scissors, and uses it both as a dissector, as a cutting instrument. And you consider 20 Rongeur coming to view, making really the work very efficient, and minimizes the in and out workflow of instruments.

- [Troy] It's actually three instruments, obviously, there's a scissor here. Now I close the tips, and I use it as a dissector. And then the third instrument, is starting with close tips, and spreading with the tips of the scissors. So it can work as a forceps as well like that. So you can use it, as three different instruments in one, and you can do the whole operation.

- [Aaron] I think that makes it so much, in my opinion, the surgery elegant. Avoids blood dissection injury to, you know, cerebral vascular structures. And really that's what's microsurgery is all about.

- [Troy] Put a blade in, lift it up, and then cut. That way, you can make sure, you're not cutting anything important underneath. Obviously this is the craniopharyngioma, that we're gonna be taking out. But again, I'm maximizing the exposure, before I even start thinking about working on that tumor.

- [Aaron] And again, your trajectory is inferior to superior, Troy, as you mentioned.

- [Troy] Right. We're not even making use, of the trajectory that we're gonna be using later. We're gonna come in much lower down here and look up. This tumor happens to protrude all the way up, into the third ventricle.

- [Aaron] And it's about 20 minutes through the surgery. And obviously you have got through, exposing the lesion, and that's counting from draping even before draping.

- [Troy] I think you might've edited a few minutes, at the most out of this video. You can see the tumors starting, to protrude through the lamina terminalis already here. There's the chiasm, A1 on the right, we're about to see if there's A1 on the left.

- [Aaron] I can see, Kaizen is very much thinned out, draped over the lesion.

- [Troy] Not much tumor in the prechiasmatic cistern.

- [Aaron] Right.

- [Troy] This floor was pushing posterior.

- [Aaron] It's almost more a subchiasmatic, and retrochiasmatic. Isn't it?

- [Troy] I would agree.

- [Aaron] Because you're really nice, Troy. You're demonstrating the working angles, that your view is giving you. As you can see, it's mainly where you remove the bone, Troy. That's where you're working. And that's why this is a skull base approach, because you removed bone, to maximize approaching the lesion, without retracting the brain too much.

- [Troy] So this is the M1, for a tumor, and we didn't show the MRI, but this is a large tumor, and for a large tumor like that, you gotta maximize all your windows. So we're going to have access to lateral, to the carotid. Obviously, medial to the carotid. Above the A1, obviously we gotta look for perforators there. Gotta worry about the pcom, the colloidal. So the more of the arachnoid planes that we open, better off, we're gonna be. But notice again, this entire dissection, we've got both epic nerves, Chi's, and A1, M1 and everything has been dissected out. And I've only used one instrument, scissors. No bipolar, no dissector. Unless you consider the scissors used as a dissector. There's tumor lateral to the carotid. So I think that these windows, they are now being exposed, to show you the versatility of the pterional craniotomy. And right now we're looking down the skull base. We can be looking up from low to high, which we'll do later for this particular tumor, that starts low. We've looked here all the way back. You can see some plaque on the posterior cerebral artery, that's going to lead to the basilar artery. So we've opened up all these cisterns. We have to preserve all these vessels. But maybe this will give you a little view, of the amount of exposure, by maximizing this bone removal. It's a very useful exposure, for so many different pathologies, and there's no reason to shortchange yourself, because nothing that we've drilled away, is gonna be cosmetically evident.

- [Aaron] Thank you, Troy. I think this is a beautiful panoramic view, of the parasellar area, and I appreciate you reviewing this with us. We'll go ahead and maybe jump, to more of the later stages of operation. Here we go. We'll go here. Maybe that's a good place to talk about.

- [Troy] So you can see where the... I use the graphics clamps. There's three of them, to hold the bone in place. I always put the first ditch, of the temporalis fascia out, at this apex here. We didn't show the dural closure. I do that in one suture, from the temporal region all the way around, to the frontal region. I put, as I said, the apex first. I'll put one near the middle. What I'm trying to do, is draw this part together and close that, without much tension on it. You'll see this in a minute. So this, just one more before we get to the APEC, or to the, what I call the burr hole cover stitch. I didn't actually put a burr hole cover, over that burr hole. Right here, I mentioned earlier, there's three leafs of fascia. And I left this little piece right here on the orbital rim, and then I left a piece on the bone flap, and then I have the temporalis main body of it. And these three things come together, and that completely covers the burr hole, and pulls the muscle up over it. And you really get minimal atrophy or indentation, unless of course the patient has a very thin muscle. And then you will. And we've closed the rest of the temporalis. We edited that out, and then we're gonna close the galea next. Questions, comments, Dr. Cohen.

- [Aaron] I think this is great. Obviously a spectacular, efficient way of doing this procedure, and tremendous experience you have. I really liked the way you have perfected this technique, and I hope our viewers enjoy. Again, watching one other way to do it. There's many ways to skin the cat, but definitely this is a very good way to do it, and I hope people will find it helpful. We'll go home back to our slides momentarily again. Thank you, Troy.

- Troy, thanks for the great video. We really enjoyed all the pearls you included. Let's talk about the pitfalls of this approach, and every step, you know, we can get into trouble, and how we can avoid those complications. So we talked about the incision shape, that you really wanna make sure the proximal and distal, and that line, stays about within a centimeter of the imaginary keyhole. The temporalis muscle dissection, you can do it one layer, two layer, as long as you're careful about protecting the fat pad, and the frontalis branch. That's what's most important. And it's really sort of disheartening, when the patient wakes up and complains, that his face or her face looks crooked. It's just something easy to avoid. The burr hole placement, I think it's critical to really dissect well, especially where you mentioned the dura can be attached, along the coronal suture or frontal area, when you're returning your drill. Any thoughts in these initial points, where people get into trouble that we can avoid.

- Now. So for these points, I think the incision is... the only thing that you haven't mentioned, is the position of the head. And that is probably the single most important thing, because if you're not positioned properly, you're not going to be comfortable, during the entire operation. You're going to be working at an awkward angle, and it's going to be challenging. Assuming the position of the head is appropriate, then your incision, there's some flexibility. As long as you can turn your flap down to the keyhole. Temporalis muscle, again, it can be dissected forward. It can be dissected down. It can be dissected in one layer or two, and everyone thinks the way they do it is right. And I'm not sure that there is a one answer. So I think there's some flexibility in that. As long as you can get the temporalis muscle, out of your way. You don't want a situation, where you have this bulk of muscle, that you haven't dissected down low enough, and then you can't look, over the temporal lobe coming from lateral, because you've got the temporalis muscle in your way. So you have to make sure whichever way you prefer, just to make sure you get, the temporary loss muscle out of your way. The fact that if you do a two layer, you raise the upper neurosis, and then you take the muscle separately, don't get into the fat pad. There's just no excuse for that. You need your dissection more along the frontal lobe, because the temporalis muscle is, ultimately gonna be raised anyway. And you'll get the temporal portion of the flap down lower, once you elevate the temporalis muscle. And the burr hole placement, and again, surgeon preference, as long as you can prevent dural tears. If you're someone that wants to make multiple burr holes, and use burr hole covers, that's fine. I just, firstly, don't do it that way.

- There's always that controversy of using Bovie, to reflect the temporalis versus, using a sort of dissector to preserve the vascularity. I think there's definitely potential. I mean, potentially nobody for sure knows, that maybe not using a Bovie, that the temporalis muscle could be more viable, but there's not been a really conclusive data, in that regard.

- I agree. I'm one that uses the Bovie, and personally, I just prefer hemostasis, and I just keep the field dry. And I just haven't had a major problem, with temporalis atrophy. Everybody gets some, maybe not everybody does. I do have some patients that have had it, do have it, but that's primarily patients, that start out with a very thin temporalis muscle.

- Thank you. Extent of frontal bony exposure, is really customized to the lesion. I think most are even large. Olfactory groove meningiomas, can be easily removed through this approach, and you do not need a bifrontal craniotomy. I haven't used a bifrontal craniotomy for a long time, unless it's for a frontal sinus fracture. And you really elaborated, the importance of the skull base approach, in this pteronial craniotomy. In other words, orbital roof and lateral sphenoid wing resections. We cannot emphasize that enough, to be able to get very low trajectory, and working angles, from inferior to superiorly. And ultimately the tack-up stitches. I mean, some people like it. I use it routinely. I know you don't use it routinely, and randomized trial, has demonstrated no significant superiority, of one versus the other. And obviously, the closure over the drain or not, that's a surgeon's preference. I don't close the dura watertight in this area, unless we're opening the ventricle in rare occasions. And we just approximately dura with a piece of gel foam, and closed it out, or replace the bowl with many plates. Any other thoughts, about those last few points, Troy?

- So couple of points on, the drilling of the orbital roof, and lateral sphenoid wing resection, particularly, if you're doing a sphenoid wing meningioma, this drilling can make your day saw much smoother, because the more bone you remove, along the dural base of the meningioma, you can coagulate that dura extraduraly, and it will, devascularize your meningioma, before you even open the dura. The more you drill, the better off you will be, from an extradural approach, when you do ultimately get down, to the Sphenoid wing meningioma. So that is extremely important, as it is in every case, but especially in a sphenoid wing meningioma. Tack-up sutures, yeah. I don't use them routinely, but if I am concerned about using, you know, I try to get hemostasis. Sometimes I get hemostasis by putting in tack-up sutures, and then I will do it. sometimes I'll just put a central tack-up suture, to hold the whole thing up. Beyond that, the other thing to be aware of, that you have not mentioned, is beware of patients that have a large frontal sinus, because every once in awhile, your pterional craniotomy will cross the corner, of the frontal sinus. You should look for that every time, just to make sure simple, to take a peek, and make sure you didn't open the edge of the frontal sinus. 'Cause then you'll end up with a CSF leak, that could have been avoided.

- That's a great point. The frontal sinus, if you get into it, you may have to enlarge the opening a little bit, remove the mucosa, and then pack it with muscle. And maybe at that time, make a stronger case for closing the dura water tight. Troy, thanks. As always, enjoy working, with you again on this session, and look forward to having you, as a guest in the near future.

- Thank you very much.

- You're welcome.

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