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Grand Rounds-Parasagittal and Parafalcine Meningiomas: Managing Difficult Cases

Michael McDermott

April 27, 2011

Transcript

- Hello, ladies and gentlemen. Welcome to another session of the AANS Operative Grand Rounds. The following session will be a discussion regarding surgical management of parasagittal and parafalcine meningiomas. Dr. Michael McDermott from University of California, San Francisco, will be our discussant. Based on your request, we have added more surgical videos to this session and future sessions. In addition, there is a series of links at the bottom of the window, the present window, which you may use to navigate within the session, and if necessary, see more of a surgical videos, thank you. Mike, thanks again this evening for joining us, we appreciate your expertise regarding this presentation. These are the description of the conflicts of interest for the involved faculty, none of which would interfere with the contents of the presentation. When one thinks about meningioma, one surgeon comes to mind immediately and that's Harvey Cushing. I thought we can include some of the special pictures that have not been disclosed before from the Cushing Brain Tumor Registry at Yale. This is some of Cushing pictures, obviously at the peak of his career in 1920s. He sketched his findings after surgery and as you can see, this is one of his illustrations demonstrating the parasagittal meningioma. Did initially the craniotomy that exposed all the tumor, as you can see he removed some of the additional bone that was necessary with meningioma and extended his incision. This tumor was completely removed, and this is the, a picture of the patient postoperatively, and a picture of the tumor, as you can see and extension of his incision across the midline. This is another patient of Cushing with a parasagittal or parafalcine anti facial meningioma, within the findings of how to deliver the tumor with sutures and instruments. And this is a postoperative image. Cushing used a human skull in order to depict the size of the tumor compared to the cranial vault. The patient did well after surgery. So Mike, we would like to talk about what it takes to remove the parasagittal or parafalcine meningioma effectively, and talk about nuance of technique, how we can, you know, manage competition or better avoid them. And before we start, I would like to ask you about some of the basic principles and pearls that you have used through your expert, you know, years of dealing with these tumors.

- I think one of the things to realize is that for some of the very large tumors, preoperative angiography and embolization can be an advantage. Well, we've published on that. I use the venous phase of the angiogram as the definitive gold standard for the service of the superior sagittal sinus patency, and make decision based on that. I think in the middle and posterior third, we accept a near total or sub-total removal of whichever degree of resection that's safe for the patients was not to create new neurologic deficit and then use adjuvant therapies or observation until there's documented growth to treat the residual tumor. I think one of the things that I've learned both with skull-based meningiomas and, and meningiomas little bones, is that now with image curving systems, we can superimpose the two-dimensional MR venograms and MR angiograms from the MR scans. And that's been, I think, an additional advantage for us in helping us during the surgery.

- Thank you. And as you very well mentioned, respect for veins doing meningioma surgery, especially the bridging veins along the parasagittal area is so important, especially if the tumor is invading the superior sagittal sinus in that segment of the tumor. The surrounding bridging veins or even maybe the inferior sagittal sinus is critical and the angiogram would warn you to where those veins are to protect them during the surgery. Is that correct?

- Yeah, I would agree with that. Certainly, damage to the veins are the spoilers of a good surgical outcome. And we always tell the patients that the arteries are fairly robust, thick-walled muscular vessels, whereas the veins are non-muscular thin wall vessels that are most susceptible to injury. And certainly one of the other things we've learned is postoperatively unlikely Alma patients, we always keep the meningioma patients well hydrated for at least two days postoperatively.

- Okay. And that's to avoid the venous thrombosis I assume?

- Right.

- Thank you. So let's go over some of the basic details. This has worked very well for me, and that's the four D's of meningioma. It's easy to memorize for the residents and fellows. And the four D's and their order, I think is especially important. And that's first, the first D is to dedress the tumor, obviously expose it. And to facilitate that, I have been very generous in terms of using lumbar drain, no matter how big the tumor is. And, you know, I, I have never had a trouble and I hope I will never will. Even with giant tumors, parasagittal tumors, or, you know, olfactory groove meningiomas. I use lumbar drain effectively, because I think the moment you use the lumbar drain to expose and dedress the tumor, it really gives you a very nice, you know, sort of quiet brain and calm and, you know, relax in order to lift the brain up or push the tumor with the brain to the side to devascularize the tumor, which is step two. And if you can devascularize the tumor effectively, I think it makes the job so much easier. Why? Because the bleeding is going to be less, you can see the planes better later, and the tumors are moving much more efficiently, because you don't have to stop at every, you know, layer that you moved to obtain further hemostasis, and obviously at the next step you have to debulk the tumor and dissect it from the surrounding structures. So I think what's most important is to expose the tumor in a very relaxed brain, whatever it takes, lumbar drain, you know, mannitol slide hyperventilation, focus on the vascular as a tumor, because the brain is quiet and relaxed and you can expose and lift the tumor or push the brain slightly without any sequelae. And the moment you got that tumor devascularized, I think the job is a lot easier. How was your feeling about using lumbar drain on large meningioma just to get a good relaxation to devascularize the tumor early on?

- Yeah, well, I serve use them frequently and I'm like you, I've not seen any herniation syndrome relate to the placement of the drain or removal of the small amount of CSF. once the bone flap is off before the dural is open to provide better relaxation. However, we have seen problems postoperatively. So we routinely keep the lumbar drain clamped for the first 24 hours after surgery to make sure the patient is well and there's no postoperative hematomas, which could rapidly expand if the lumbar drain was routinely left open. And likewise, we used to, at some point, postoperative remove the lumbar drain and leave the patient flat for two hours, but we've seen too many CSF leaks after the drain has been removed that are cut, meaning there's no leak out from the skin surface, but the patient has all the symptoms and signs of herniation syndrome. And so now we remove the drain, leave them flat for six hours.

- Yes. And so I would just remind people to keep that in mind, if you have to using a lumbar drain, you take it out postoperatively and the patient deteriorates significantly. So think about in a cut CSF leak at the side of your lumbar drain.

- Okay. So am I understanding correctly, that no matter how big the tumor, seven, eight centimeter parasagittal meningioma, as long as there's no obstructive hydrocephalus, you're comfortable with the lumbar drain as long as the lumbar drain is clamped or removed immediately after surgery and watched for evidence of intracranial hypotension or evidence of occult CSF leak, am I correct?

- We always, we will leave the drain clamped for the first 24 hours, we will not remove it, because if we remove the drain there's the chance for an occult leak-

- Okay. that we'd have difficulty stopping. So we leave the drain in place, but leave it clamped. And then if we need to use it, we will. But if we don't, we'll usually remove it and leave the patient flat for six hours after the drain is removed. We used to only use two hours, but we've had problems. So you remove the lumbar drain and you think the patient is able to tolerate being flat for six hours in the postoperative period.

- Okay. Thank you. But you haven't had a problem with using lumbar drain in terms of herniation syndromes in the operating room, because you were draining CSF from downstairs while you're pushing on the brain just to have a relaxed brain?

- No.

- Okay. Thank you. This is a distribution of meningioma and as you can see, almost a quarter of meningiomas have parafalcine or parasagittal. So these are important group of tumors, very, you know, desirable for the surgeon, because they're benign usually, they do not violate the brain, and their resection is often associated with a very good outcome. And so were the ideal surgical tumors. So let's focus on the nuances of technique for parasagittal and parafalcine meningiomas. This is the position we have come to use, Mike. And I would like to know your opinion, the patient's place and opinion, as you can see, the pressure points are well padded. One point that I like to make is not to elevate the head of the patient too much for the fear of air embolism. Not to feel like you have to look down when you operating there, that you may look straight on. What, what's your feeling about positioning of the head for these tumors?

- Well, usually anterior third, we'll use the position you've depicted here. When it's in the middle third, the posterior part of the skin incision gets a little bit difficult to manage. So we'll probably put the patient in a semi-lateral position, turn their heads somewhere 40 to 60 degrees. And then in the posterior third, depending on the depth of the tumor, relative to the surface, we'll either use, you know, a full lateral or a three-quarter prong. And again, depending on the depth with the operative side dependent, so that we can use gravity to retract the hemisphere or for the deeper lesions.

- Thank you. Again, this is for a middle third, and I think you mentioned that a lateral position may be ideal and I will show a video of that actually, where we did use a lateral position as well. And I think that's a great point. Obviously, if you put this side of the tumor down in lateral position, their will, the gravity is going to help you, the chance of air embolism may be less. And I think those are the nuances that are important for position of the head for tumors during the middle third. This is a craniotomy, let's say for an anterior one-third, and I have liked to, I usually place the burr hole right over the sinus, obviously turn the bone flap all the way before making the final cut over the sinus. Do you use a curvilinear incision, Mike, or do you use a linear incision there?

- Well, it depends on where the tumor is located. Anterior third, obviously for cosmetic reasons, the incisions should respect the hairline. And even for patients, males with a baldness, you know, in those cases, we prefer a coronal style incision or what I call a big C-shaped incision from the temporal region behind the tumor. One of the things I, that I've come to use routinely over the years because of difficulties with separating this dural from the inner table of skull is what we call a bipartite bone flap, meaning a two-piece bone flap. So unlike your demonstration here, we'll put our burr holes lateral to the superior sagittal sinus, in the paramedian location. And then under direct vision, that separates the midline dural and superior sagittal sinus from the inner table of the second piece of bone, which crosses over the midline to the opposite side.

- Okay. And I've always found that whenever I wanted to be very close to the midline, and I didn't cross it, I was always wishing later on that I'd actually crossed over because I was compromised in some way, so we can get very good cosmetic results now with a two-piece bone flap using countersunk titanium plates and using hydroxyapatite to fill the gaps. And the thing about the hydroxyapatite is that prevents the fibrous union in the, in the, in occurring between the bone flap and the surrounding skull, and it, I've learned from the plastic surgeons that it's that scar, that fibrous union, that attaches to the overlying galea, which is part of the reason that patients get dimpling in the skin over the bone flap. And if you use a hydroxyapatite, you don't get that at all and the patients can have a very good result.

- Thank you. So you use a two-piece. The first piece is on the side of the tumor-

- Correct. and not exposing the sinus and then you use a smaller piece of bone over the sinus and lateral, while you have a good visualization of the sinus, when you dissected underneath the bone, the second part of the bone?

- Right.

- And that makes sense, it makes it safer for the sinus. This is the dural opening. I think that's pretty standard as C-shape while watching for the bridging veins.

- I would, one thing I would say to the, the residents here is, you know, the, the dural opening doesn't have to be a perfect U-shape. So you can filet the dural opening as much as you need to, to follow and respect the parasagittal draining veins.

- Okay.

- And, you know, with, with the methods we have for a dural closure, I don't think the risk on the convexity of a CSF leak is a major consideration. So I would open the dural whatever way I need to in order to respect the veins.

- Yeah, veins come first. And so that's the standard we should have for opening the dural. Thank you. If the, a little bit of the tumor is attached, especially in the case of parasagittal meningiomas, one may try to dissect it off first to sort of get everything released and then remove that dural at the end, or obviously remove it at the beginning. This is I think what you were referring to, Mike, if I'm correct. You can see the dural over the bridging veins has been left alone, and this is a depiction by our artists. Again, showing that the dural over the area of the bridging veins, because as we all know, the bridging veins may enter the dural lateral to the superior sagittal sinus in the legs, and you don't want to sacrifice any of those legs. And so it's better to leave a piece of dural over the bridging veins to protect them. Do you have any other nuances besides what we show here to protect those veins, Mike?

- No, other than the realization and, you know, in the anterior half of the superior sagittal sinus of the course of the parasagittal draining veins, close the midline at the anterior, and then somewhere between the middle and posterior third, it becomes the, the veins close posteriorly into the superior sagittal sinus of the direction as they come close to the midline as the opposite, opposite the way that is depicted here.

- Okay. Thank you. And again, this is sort of showing how you devascularize the tumor from the edge of the dural, just lateral to the superior sagittal sinus. And again, the dural that's left on the bridging veins. Again, the, I have gained a lot of respect for the veins, especially for meningioma surgery. And I think we cannot repeat that enough in terms of protecting all these bridging veins since any other sacrifice could lead to venous infarction and unnecessary postoperative morbidity. This is the second stage really devascularizing the tumor. I think having a lumbar drain here tremendously helps, because you can retract the tumor with the brain without debulking it. Get a good devascularization early on, and don't struggle the entire case trying to be within the tumor, removal of the tumor, spend an extensive amount of time, you know, coagulating, remove another layer, you know, spend additional amount of time. So getting sort of the root of the mushroom, you know, all these meningiomas are mushroomed, not all of their, you know, surface to the falx is their base. It's just getting that mushroom's root off of the falx, I think is important. Again, the next stage is debulking the tumor after it's been devascularized. And again, using the carotenoids to wipe the brain away from the tumor, and sort of lining the surface of the brain, protecting it away from the tumor and sort of wiping it as you've seen the action of the carotenoid here to move the brain away from the tumor. Do you have any other thoughts, Mike, about how to take the brain off of the tumor and these meningiomas?

- Well, I think, you know, it depends on what you're anticipating of this tumor brain interface to be from the preoperative imaging. So if there's abundance surrounding Bayesian academia, you know that the arachnoid plane open violated by the in-growth of the vessels from the peeled surface towards the tumor. And so it'll be, you'll have to isolate those little tiny arterial branches coagulate and divide them. But if your arachnoid plane is well preserved in a case of a meningioma with a smooth border, no surrounding edema, I think you can use the methods you've displayed here in combination with sharp dissection techniques under the microscope, you know, to maintain a good interface and remove the tumor without injury.

- Thank you. And again, removing the falx that was initially coagulated to make sure maximum amount of effort has been placed in terms of preventing recurrence. Obviously, age of the falx that's been left should be also coagulated to reach a good Simpson grade in terms of resection. I have found removing the falx here would really create a huge corridor to remove those tumors that extend on both sides of the falx no matter sometimes how big they are. Do you agree that most of the bilateral parafalcine meningiomas can be resected unilaterally, as long as you remove the falx, or to open the corridor to the contralateral side, Mike?

- Yeah, I think they, they can be, but I think you should be prepared with your operative setup to be able to provide access to both sides, particularly in those meningiomas that have an irregular surface, or again, those meningiomas with a lot of edema in the adjacent brain tissue.

- Okay.

- One thing, a couple notes here, when we talked about the devascularization process, if you have a large anterior middle third tumor, you know that some of the blood supplies can be coming from the falcine artery. And so frequently what I'll do is, I will open the falx anterior to the tumor and then insert that directly down right through to the bottom edge of the tumor, which usually will eliminate the anterior falcine artery supply, which helps as opposed to trying to detach the tumor completely from the falx as a method of devascularization.

- Okay. And the other thing I think that we should be aware of is that, you know, sometimes there's venous drainage into deployed channels in the bone. We've been caught previously with, for example, a patient with an olfactory groove meningioma where we thought using skull-based techniques to limit brain retractors could be helpful, little did we realize that the entire venous drainage from the right frontal lobe went into deployed venous channel, down the midline, out through the super peripheral margin. So when I did the super velocity only I eliminated the venous drainage from the right frontal lobe with the expected result. We've also had patients. So we, we pay a little bit of attention to the MR venograms looking for evidence of deployed venous channels. And I've actually operated from the other side, operating from the right to remove a left-side of faulty meningioma, right now on the preoperative venogram, I've seen that the patient has deployed venous channel on the side, it's lateral to the tumor. And so being, you know, a little bit wiser, because I've had problems in the past. In that case, for example, we operated from the right to remove the left-sided tumor with a good result.

- Okay. Those are great nuances. Thank you, Mike. And I think one other point is when you remove these tumors, the pericallosal can be very much displaced and attached to the tumor, especially in the large ones. So the devil is in the details when you're removing that last piece and you're tugging on it, and you're like, this is the last piece. Let me just pull it out. And that's usually where the worst things happens, as you tug on a branch of a pericallosal or callosomarginal and you cause periarterial injury. And what are your thoughts about the deep arterial branches, and how should we be careful about protecting those?

- Well, I think, you know, as you said, 90% of the good outcomes are in the last 10% of the tumor resection, and I've seen exactly what you've described happening before. So I think just that patience is a good virtue on the last part of these tumors, even when the operation's been long. If you anticipate that, you know, you've got a six-centimeter tumor and it's going to take you longer than six hours, then you should get one of your colleagues listed as a co-surgeon for the case and plan to take a little bit of a break at some point in the case. But I think end of microsurgical technique, making sure that the vessel that you think is supplying only the tumor, that you don't sacrifice it until you see beyond the posterior edge of the tumor confirm that this is not just undecised vessel, giving a few little twigs, but it's important to end artery for the brain. I think those are the things that'll, that'll make a difference for you.

- Thank you. Managing air embolism. I think everybody should be ready for that. High index of suspicion is probably the most important thing. Suspect the diagnosis if the patient is hypoxemic, hypercapnic, hypertensive, and there's no good reason behind it. And maybe there was some arrhythmias, and the best is to expect and prepare with a Doppler ultrasound. If you feel like you will have, you know, venous bleeding and the head of the patient is above the heart more than you liked it to be. And if it happens, I think this important steps are wax the bony edges, flood the field, watch for any bleeding points, especially venous and coagulate the small veins that are bleeding, lower the patient's head to see where, where are the bleeding coming from out of the venous structures, and to cover the surgical field with a wet sponge, ask an anesthesiologist to stop the nitrous oxide, and most importantly, be patient and let the anesthesiologists manage some of the symptomatic changes in vital signs while you were lowering the patient, the head of the patient and putting the wet sponge to first stabilize the patient. Do you have any other nuances in the case of the air embolism, Mike?

- No, if, if you're going to use a position like semi-sitting or a position where the head is obviously above the heart, one of the things we always do is do a, what's called a, a bubble echo, which is necessary to rule out a right to left shunt.

- Okay. So the preoperative cardiac ultrasound they'll do with agitated sailing, injected rapidly intravenously, and then be able to detect whether not that patient's got patent atrial septal defect. So we do that always. And then the, all the things you've listed and if you're really in deep trouble and if there's any anesthesiologist says the central line, they can aspirate. And if you don't have the central line, they can just progress with the jugular veins in the neck transiently until you find that. Because one of the things with air embolism is you won't see venous bleeding at the site of air induction because you're sucking air in. So there's no venous bleeding.

- All right.

- So it's a little bit difficult to find. And sometimes when you do lower the patient's head or compress the jugular veins, that's when you'll see the site where the air is being entrained.

- Thank you. Managing dural venous injury. I think, especially for people like me who put the burr holes on the dural and maybe this is more applicable. But if it is, if it's an anterior one-third, as you can see here, there are two types of injuries, Mike that I have seen and both of them has happened to me, unfortunately. One is putting the burr holes on the sinus and causing the longitudinal injury across the superior sagittal sinus. And so like in this case, just going from one burr hole and another, and just opening slain open the sinus. And the other one is when you're opening dural, as you can see in this illustration, you nick the edge of the sinus, and maybe that's just because there is a dural ends and venous flank that's extending more lateral, and you think you're not close to the sinus, but you just nick that the venous leg and starts bleeding. And the worst thing you can do is put the bipolar on that thing, because it just makes the dural shrink, and it even bleeds more. So I would like if you don't mind to just to take a moment and if you have a middle to posterior one-third sagittal sinus injury longitudinally, which is a very unfortunate injury, I think it's best to be calm and manage air embolism if it's present, then try to put some fibrillar that we use, I think there's other hemostatic agents, and then remove additional piece of the bone to expose the injury, cut a piece of dural as you can see here, while you have the fibrillar on the, you know, cut sinus and then rotate the sinus, leave the fibrillar there and sort of create another sinus if possible, or a wild sort of roof for it. And that's worked for us. Thanks God, we didn't have, we haven't needed to use it too often. And in another case where you're cutting the edge of the dural, as you can see here, and you run into a venous leg, the best thing to do is not to necessarily bipolar the edges and open the cut, but rather get a piece of muscle, pass it through a stitch, and you can get the muscle from temporalis muscle, and then sort of suture across the cut on the lateral edge of the sinus and let that piece of muscle, as you can see, work as a pluck. What else do you use Mike, in terms of the details we talked about?

- Well, you know, this is where the two-piece bone flap really shows its advantage, because number one, you're dissecting the midline under direct vision, and number two, if you get a tear you have the whole sinus exposed. So we usually ask the nurses to have one by three pieces of Gelfoam ready to go before we do that midline dissection and do the cut. And so I, I've used the, the Gelfoam to lay it over any venous legs or small openings and I've not really ever had a problem. You know what you said here about suturing muscle, and I think is a good idea. I agree that bipolar ring tends to make the hole bigger. One thing we've done more often is as you, I guess, one McKissick told my old boss, you know, he said, "Relax, it's only blood." And I, I think that's important. You don't panic when, you know, a little bit of venous bleeding. I think sometimes you can put a small 5-0 suture in these lateral tears that you've made and, and suture directly, which gives you nice control and it's less compromising to the surrounding vasculature than even putting a wet clip on it. So I do use small patents of either muscle or folded over surgicel when we've got, for example, in a posterior third, big period torcular, this trans diplod vein that we can see on the preoperative GAD image. We were anticipating we see it, when we get the bone off, we can't stop the bleeding, the pressures are high. So in that case, putting a piece of Gelfoam was never going to work. So I agree with you. I usually do a figure-of-eight suture over a muscle or a surgicel patent being careful not to tie it too tight, such like I compromise the, the superior sagittal sinus, but I will tighten enough so that this thing is not going to become dislodged in the middle location.

- Thank you. Again, I wanted to include this just to emphasize the importance of lumbar drain in meningioma surgery. Let's go ahead and proceed to our case presentation, which is essentially the most important part of this presentation, Mike. And let's start with a standard parasagittal meningioma. This is a patient of mine a 58, you know, a 50 year-old male with progressive history of left-sided weakness. And this is his MRI, again, showing what it looks like a meningioma. And I know the enhancement is not very characteristic. Usually, the meningioma is enhanced more, but this turned out to be actually a regular bread and butter meningioma. As you can see the base of the tumor currents drastically, just, you know, around the area of the superior sagittal sinus, the sinus is patent in this case. Often you can see some of the draining veins in this area, not always that have to be protected. This is the amount of edema associated with this meningioma. You know, I have used both, both a C-shaped incision in this case, I think the C-shape would have cosmetically been acceptable. This is how we placed the Mayfield retractor on the head. I'm sorry, the Mayfield head clamp on the head and the linear incision, obviously defining the midline using the stealth, if necessary. Again, showing the extent of incision from one side to the other. And this is really after we reflect the flap, it gives you plenty of space in terms of exposing the bone and placing the burr hole all over sinus. I, I understand that your method most likely is safer for the sinus. My experience has been the dural over the sinus typically ends up to be the strongest. And if I can see the sinus from the beginning I feel more comfortable, but again, if one decides to use that method, that's sort of where the two burr holes are placed. The first cut, obviously not over the sinus, because if you get into trouble with the sinus, you want to be able to remove the bone flap immediately. And here's the bone flap removal, and you can see the edge of the sinus over the middle and more medial portion of the tumor. And here's the video of the surgery, as you can see, exposing the tumor, this is the superior epidural for the superior sagittal sinus. The dural has been retracted. The devascularization has been completed. And again, this is falx cerebri. Any stats Mike?

- No, just other than what I mentioned previously, that you could divide the falx anterior to the tumor and eliminate some of the blood supply rather than having to deal with it off fast along the falx.

- Okay. Thank you. And here's after the tumor has been thoroughly devascularized. we tried to stay within the arachnoid membranes if possible, and sort of continue exposing or as we say, dedressing the tumor in this case. The tumor then coagulated, debulked and shrunken. And again, this is a basic meningioma, classic parasagittal meningioma resection, nothing fancy about it. I included this as the first video, just to start our discussion. And then eventually after the tumor is thoroughly debulked, you can obviously try to remain within our arachnoid membranes if you can, but in this case there was good amount of edema. And then the brain interface to the tumor was very much adhering to the, to the tumor. And then we sort of use the carotenoid to wipe the brain off of the tumor, sort of place it underneath as you mobilize the tumor and ultimately deliver the tumor. Let's go ahead and review our second case. Again, this is the postoperative MRI from the first case, showing reasonable tumor resection without complicating features. This one is more of a challenging case, Mike and I would like to hear more about your opinions. 52 year-old female with only headaches. Really no other symptoms whatsoever, neither seizures, weakness, or memory difficulty. And this is the tumor parafalcine posterior meningioma, not much edema or none at all edema on the MRI. She's a young lady. Would you recommend treatment or would you watch this tumor?

- Well, I mean, it depends on, you know, symptoms, signs of whether those correlate with the tumor position. So the patient had headaches alone. Given this location and size, I'd be wanting, you know, to look for evidence of peripheral edema that correlate with her headaches syndrome. And then if her headaches were interfering with her ability to function in everyday life, then I would recommend, you know, that she considered surgery. 30% of these tumors will grow in the first year of observation. Other figures are a little bit variable in the literature, but it's not calcified. And so I think it's likely that in her lifetime, and certainly even in the next five years, this will be documented to grow.

- Okay. And that's exactly what we did. This is the preoperative venogram showing that the all the deep venous structures are intact. This tumor did get close to the vein of Galen. And I think this really goes back to what you mentioned in terms of positioning these patients in the lateral position, using a C-shaped incision and letting the, the gravity to be your friend. Is that how you would have done this case or different position?

- Yeah. No, I think this is fine. Same. I might've based the skin incision back here, inferiorly, but just so they'd be in the parallel to the direction of blood supply from the axial of the arteries, but certainly crossing the midline. In this imagery you can see the patient's down, shoulders tucked up under her ear. So if you put an arm board extension on the top of the, or a table, that will tend to drop that shoulder down, or you can just put it in a sling over the end of the bed, similar to a three-quarter prong position that will help you with avoiding venous constriction and elevated pressures.

- Thank you. And this is again, other views of placing the head clamp just to reach that ideal position. I think the arm here was sort of on the, over the mattress there. And again, are you sure of this, because I think the lumbar drain still is important part of this tumor resection, because this is a parafalcine tumor. So you do need to retract the brain to reach it. And you really don't want to injure the brain on the way down to devascularize it. So, and this helped us tremendously. And let's go ahead and review this surgical video. Again, here you can see the superior sagittal sinus. The dural has been reflected over it. I have come to like, to put the stitches right actually on the falx inferior to the superior sagittal sinus to gently retract the sinus with the sutures and get an extra few millimeters into the intrahemispheric corridors, corridor, Mike. And as you can see here, I'm putting some Teflon to control, sorry to protect the brain, go down the fall of the falx down. Initially devascularized the tumor drain some CSF. Continue all the way to the edge of the falx and where the inferior sagittal sinus is. Any thoughts about how you would have done this, Mike?

- No, I think similar to you, I would have crossed the midline. I think if you do a bone opening, it doesn't cross and use those faulting sutures and retract too hard, you might be at risk for interoperative sinus thrombosis, which we've seen with the so-called extended retrosigmoid approach where the entire sigmoid sinus, or at least most of your one-half of it is exposed and then the dural is reflected back up over the bone. And I've had that experience once. So I would have crossed the midline with same exposure as you're documenting here. I would have superimposed the MR venogram on the axial 2D images for this Delta brain lab systems to help me with my proximity to the vein of Galen that's the falx and the tentorial junction.

- Thank you. And as you can see here, the tumor is being dissected off of the brain and being delivered after it's been devascularized. And I think this is additional piece that's coming out. Here is the falx that's being removed in order to, I think a small piece of the tumor did cross the midline to go to the other side. And cutting, you know, the falx has to be very carefully done, putting sponges on both sides and sort of cutting the inferior sagittal sinus carefully. Obviously, you want to make sure it's not a dominant venous drainage as you very well mentioned. And to compromise it, if the superior sagittal sinus is compromised. And here's the tentorium, here's the falx, this is falcotentorial junction. And we're trying to remove the tumor at that junction, just like where the typical challenging falcotentorium meningiomas are. And here is me trying to cut the edge of the tumor, as you can see within the cell venous bleeding. And initially we thought maybe we injured some of the deeper, more important venous structures. And, you know, again, I'm not sure bipolaring this is the best idea as it could potentially increase the bleeding. What are your thoughts in these situations, Mike?

- Well, I mean, I, first of all, I would have probably been a little bit more conservative than you were in that region in terms of trying to excite the falx. But if I had bleeding like this, I, I'd have the same concerns that this is possibly one of the deep venous structures. But don't forget that apart from the bipolar you've got, you know, wet clips are awfully difficult to apply in that region.

- Yes.

- But there's no, there's no harm in using an aneurysm flap to get, you know, control just with the little edge that might be bleeding. Because you can manipulate it, take it off, put it back on, et cetera. And whenever we do falcotentorial meningiomas where the tumor has occluded the straight sinus, and the last bit of tumor is attached to the vein of Galen, we, that's where we use two aneurysm clips, clip the vein of Galen, which is flowing the opposite direction and then just cut the stump and remove the tumor completely.

- Okay. That's a good nuance. Here is just, I think that we were lucky to just find out this was the interference of the inferior sagittal sinus and coagulated and got good control. Again, I tried to be aggressive at this falcotentorial junction. I'm not sure that is a good idea. This is again, that extra pieces of falx attached to the tentorium. We did leave a very small piece of the tumor, as you can see here, Mike, and ultimately delivered the whole falx and the tumor on the other side as you can see attached here. And got a reasonable good reception, here is the tentorium of falx. And maybe very tiny pieces-

- The one thing-

- Yes. I've come to use quite a bit is for completing some of the coagulation, if you will, of the residual attachments for these tumors, using that, using a CO2 laser, low power setting, deep focused, and the nice thing about it is the vaporization, so a tenth of a millimeter at a time. So you can slowly whittle away some of these residual attachments. And I, I think it's been helpful.

- Thank you. This is the postop MRI from her. She did very well without any sequelae. Let's go ahead and talk about another challenging case. A 62 year-old white male with one episode of a generalized seizure. And this is an MRI. And as you can see in the MRV, the sinus is completely occluded, but what happens in these cases is some of the veins and very important there's a twag around the tumor, but then drained backwards to where the sinus is patent, not right next to them. And so it can be tricky that the surgeon says, "Well, these are the veins just next to the tumor that couldn't possibly be important. Maybe I can sacrifice them." And I just wanted to make a point of that if you don't mind, and we can review the surgical video again. And here you can see some of the veins that move posterior to drain to where the sinus was patent, just behind the tumor. I'm going to go ahead and bring about our second video set. I think that's where our next video is. And here is what you can see, Mike. The fact that this is anterior. For me to orient you. This is residual falx. This is posterior. This is some of the tumor left, and the tumor had invaded the brain. So posterior, anterior, and here is trying to remove the last pieces of a tumor. I tried to abbreviate this video because the interesting part is usually the last pieces of the tumor. And here is the falx somewhat infiltrated. And we're going to go ahead and cut it at the end. And as we moved, and you can see an extra piece that's being delivered. Again, doing a bilateral craniotomy on both sides of the sinus. The superior sagittal sinus, which was occluded was completely removed. And here is moving backwards where these important veins are joining posteriorly where the sinus is picked. And then this is the stump of the sinus that is picked and that have elevated. Here's trying to cut the falx now that is infiltrated. Your thoughts about doing this any way differently, Mike?

- No, I just wondering on the preoperative of MR images, whether there wasn't a collateral venous channel at the bottom edge of the tumor, either within or adjacent to the falx. So that the superior, the inferior sagittal sinus was taking up the bulk of the work. So I would have looked at that on the MR venogram or the angiogram, and I saw it on the coronal MR image I saw on the bottom to the left of midline. Yes. So that upper left-hand image, if you see there's a signal flow void right, right there. Yeah. Right. The black mark at the bottom of the falx, just to the left of that, that's it right there.

- Okay.

- So I would have wanted to know whether or not that was the equivalent of the superior sagittal sinus from this patient, and paid attention to that and obviously interoperatively looking for it.

- Okay. So you may have done an angiogram and I studied that a little bit better. So here is sort of moving forward and trying to remove this falx. We did not run into a venous channel, although knowing it before surgery should make the surgeon more comfortable. And I appreciate you input in that regard.

- Yeah. One of the things we've also used apart from displaying the MR venogram on the image-guidance system is interoperative Doppler. So we can correlate what we think is the last or the front edge of patent sinus with a color Doppler that we use with a simple probe and the, the color displayed on the Doppler will tell you the direction of flow of blood. And you can correlate that with image-guidance system or direct standard touch probe, which gives you the audio feedback that the sinus or vein is open. So we've used all those adjuncts in helping us get the resection like you've demonstrated here.

- Thank you. And as you can see here, Mike, we're coming to the critical part of the operation. You see the vein comes all the way anterior. This is the stump of the sinus that's infiltrated with tumor. And it's tempting to remove this and potentially sacrifice. Whereas, as you can see in this ICG, I have used ICG just like I used for aneurysms. And you see the vein is patent going into the sinus.

- Yeah.

- And that's told me that you have to preserve this vein. This main should not be sacrificed. And therefore, we avoided removing the last piece of the tumor that was over the sinus and that segment and the patient's postoperative MRI looked reasonably well without any evidence of this evidence of a tumor. You obviously would have kept all those veins intact as well, correct?

- Yes. And I, I think the ICG green is, you know, another great adjunct to use. One of the things when the tumors are like this and the sinus is occluded in the middle third, is that whenever you take these tumors out, the patients almost always have a biparietal joint position sense deficit, which in the absence of weakness makes it difficult for them to ambulate postop.

- All right. I have had patients, and actually this patient ultimately did well, but for the first couple of weeks had a dense, bilateral lower extremity weakness. And some of my colleagues have had the same experience. So if you do a bifrontal, posterior frontal, parafalcine tumor, and with invasion, it is almost at times inevitably double, that's there's some bilateral lower extremity weakness. But if you haven't sacrificed a big venous structure, arterial structure, uniformly they do very well. Isn't that correct?

- Yeah. I think so. In a few void arterial injury, obviously, you know, in the long-term they should do fine. Look at the postoperative DWI images to try and predict, you know, what you might anticipate. Because if you have an arterial injury, the DWI will be positive right away. And if it's venous, not so.

- Okay, thank you. Let's go ahead on the next case, this is pretty a nice dramatic story on a 42 year-old homeless man who was found unresponsive most likely because he had a seizure. And he, he was really somebody who was very successful 10 years ago. Had radiation for leukemia to his brain as a child. And from a very successful executive, became somebody who was living on the streets. And here is his tumor, some of a daunting tumor, Mike, because of its size and the first thing comes to mind, where the heck are those vessels? The pericallosal, callosolmarginal are going to be a nightmare to dissect through. And here is the tumor in T2, and you can see the vessels on the periphery. And then I went ahead and did a CT angiogram and a venogram. And just as you mentioned, studied the vessels and sutures everywhere engulfed and attached to this tumor. What are your thoughts about these challenging cases, Mike?

- Well, I mean, obviously that patient's got, by history of frontal lobe syndrome related to this mess and given the etiology, meaning radiation-induced, might be more likely to be atypical. Doesn't look like it's necessarily malignant, but here, you know, you'd have to, in order to get a good neurologic outcome, we're going to have to accept a subtotal removal and do everything we can to preserve those arteries if we want the patient to, you know, to walk out of the hospital postop. So I'd be telling the patient and family that we can remove most of this, but not all of it.

- Okay. Thank you. And that, you know, that's exactly the same discussion I had unfortunate as an editorial note. His family had left him many years ago because of his behavior changes. So after a group went through the appropriate procedure, procedural things in terms of getting the consent, this is the, you know, by frontal skin flap incision, craniotomy on both sides. This is one case that I did not think from one side, you can cut the falx and remove both sides out, both tumors, I think that's too big of a tumor, and you're not going to have a good view of the vasculature on the other side or attached to that capsule or potentially incorporate it. So this is an, you know, interesting tumor, as you can see, this is the craniotomy. The flap of the dura has been open first on the right side, we did use a lumbar drain in his case, even though with this big tumor and retracting the brain gently in order to start removing the tumor. And as you can see, sort of trying not to retract the brain tissue, and here is the callosomarginal artery, dense in this tumor and we tried to use a CUSA sort of like to try to debulk the person. We spend about an hour dissecting microsurgically this callosomarginal that you can see here, Mike.

- Yeah.

- Through this dense tumor, And I thought I have accomplished a lot. And you know, I'm preserving this thing until I got deeper. And this become essentially within the tumor, and again, using microsurgical techniques, being patient, cutting this sort of vessel, the attachments, and here is the vessel going deep into the cleft of the tumor. And as you can see, the whole length of it has been dissected, you know, try to preserve it. And as we got closer, the wall became so incorporated that as I tried to dissect the dough, as you can see, an injury occurred and we just had to sacrifice the vessel at that point. I just, you know, I, I guess I could have removed the tumor and just left a sleeve around it, but when it's so much within the middle of the tumor, do you have any thoughts about what to do?

- Well? I mean, I would have done what you did, and the same thing has happened to me, you know, with injury to an artery that I was initially hoping to save. I think as I've just gotten older, I'm less concerned about removing all of the tumor than I am about, you know, leaving a little bit of tumor behind and hopefully getting a good result. Although sometimes you can, you can get lucky and if there's good collateral supply, and you can think, oh my God, the patient's gonna end up with a, you know, arterial infarction. And you're surprised postop that they're fine. So, you know, it's not possible to predict all the time, but I think you do your best and, you know, think about the patient first rather than what the postoperative imaging would look like.

- Thank you. So we did the reasonably good resection on that side, so I did not even encounter the pericallosals. And I thought maybe we're all good. The pericallosal are out the way. Well, we came to the left side. And we removed the tumor, as you can see here, Mike. And here is the pericallosals everywhere attached to the bottom of this tumor. And one bad news after the other, trying to protect all these pericallosals, and you can see the vessels at the bottom here, and trying to preserve them as much as you can. These are some of the attachments. And the last piece is coming out I look and the pericallosal is in. It's going in and nothing is coming out. So I do a Doppler, the pericallosal is gone. And try to do all I can. So we lost one callosomarginal on the one side and we lost the other pericallosal on the other side. And so I was thinking this poor guy, you know, is just devastated and here is the postop sort of at the end, what it looked like in terms of the resection. And as you said there, it's sometimes better to be lucky than good. And in this case, this guy did have a very good, generous collaterals, most likely from, you know, postop corridors or postop circulation. And as you can see here, postoperative he had a good resection three months later. And really no evidence ischemia on FLAIR images. And he's actually back to work doing very well, because of his bifrontal syndrome that he had before surgery that's improving. 55 year-old female with severe headaches. And this is more of a bread and butter. Maybe we can see every day a bilateral, posterior frontal, parafalcine meningioma. Is this a case that you would do through craniotomy on both sides or mostly at one side cutting the falx and removing the other side from the ipsilateral side?

- Yeah, I think he could have got this from a right side of the approach predominantly.

- Okay. Any other consideration or nuances for this case, Mike?

- Well, I can see on the coronal image that the enhancement comes right up to the base of the superior sagittal sinus, and on the right-hand side there's a large signal flow void. So I'd be thinking about a large, paracentral draining vein there.

- Okay.

- And I can see on the opposite side on the left, there's an artery adjacent to the capsule tumor. So I'd be thinking about that the whole time I was operating, anticipating, and covering him.

- Okay. And thank you for mentioning that because you read my mind as we are gonna review the video in this case. So let's go ahead and bring up the next video, if you don't mind. Mike, this is opening the dural on the right side. And again, I was thinking about that vein that you can see right here, and it's attached to that dural and you can not go medial to get into the intrahemispheric corridor. And what did we did in this case is again, cut the dural just like we, you mentioned previously. And number one thing is to protect the vein, especially a large draining vein like that is definitely not a spare part of your body. It is something important. And during the cutting the edge of the sinus, you, I got into a venous leg, and just like you mentioned, I put a figure-of-eight or just a regular stitch led that by polarizing it and extending the tear into the sinus, just putting a stitch in there and really pretty much nicely stopped bleeding. And again, putting something on the brain to protect it from the heat of the microscope and then proceeding to devascularize the tumor, again, using a lumbar drain to get a very peaceful train in the brain, as you can see. And devascularizing it, I thought exactly about going very anterior, as you can see here, you mentioned the coagulating of the falx. I think you see that right there. This is the start of the pericallosals deep and coagulating the anterior of the falx in order to get an early devascularization. Any thoughts there?

- Yeah. I've actually, I have a right angle bipolar that I use predominantly for tuberculum meningiomas, but it turns out to be very handy when you're having to coagulate the, the falx like this, so you get to basically turn the right angle so the blades are along the axis of the falx you want to cut. This makes it a little bit easier for you.

- Okay. And here is all the way devascularizing the tumor to expose the pericallosals. And they're really going around the tumor. This tumor was very adherent, as well as you can see, I tried to retract as much of the falx and protect the brain, but it was relatively deep and tried to use that carotenoid technique, you can see, try to again, protect the brain as much as possible by wiping the brain away from the tumor, obviously if there's a good direct membrane you would like to preserve that through microsurgical techniques. This is going back trying to protect the brain and then cutting the falx in order to reach the tumor on contralateral side. And again, using a 15-blade and carefully cutting while you cover the brain so the knife doesn't touch anywhere you don't want to. And then as you gain access to the other side, cut the falx. Any thoughts here, Mike?

- No, just sometimes when I'm cutting the falx like that, I'll use a hook in the falx to pull it away from the contralateral medial surfaces of other hemisphere. And then I've found that a smaller blade like arachnoid knife or bivab pharma clutters are handy.

- Okay. And that I use that. I think I'm going to show right now what you're talking about, I hope that's a colen knife, a hook knife. You're right there?

- Yeah.

- I think that works beautifully in this area, because you move up and carefully sort of look underneath what's your cutting rather than just sort of be blindfolded. And here's the tumor on the other side, getting delivered with a falx, initially just removing the tumor and then coming back removing the residual piece of the affected falx. Any other thoughts, Mike?

- Nope.

- I think this really creates a nice corridor by cutting the falx. You not only get the, a better Simpson grade resection, you also avoid a bifrontal or bilateral craniotomy with its own attended risks. And I think, again, going ahead and cutting additional piece of the dural that is effected by the tumor. And you can see the, I think one of the branches of callosomarginal on the other side that you can see as you're cutting the falx. How long do you continue preoperative anticonvulsants, Mike?

- Usually, I follow a guide, I follow the severe head injury guidelines and use them for a week. That's going to be one of the, that's going to be the first trial we hope to open with the clinical trials subcommittee of the section on tumors is a prospective randomized trial of any convulsions or not for, you know, convexity and vault meningiomas.

- Okay. So this is I think one of our last case. 85 year-old female with confusion. And the family says is just not acting right and they do an MRI and this is what they find. At age 85 with diabetes, would you be aggressive about offering surgery, Mike, or, or what are your thoughts? It's just some mild to moderate confusion.

- Well, I think it depends on what the patient's, you know, premorbid status was. I mean, diabetes as a comorbidity doesn't prevent me from recommending surgery. What would would be, you know, in the 6 to 12 months prior to the patient developing a frontal lobe syndrome, whether they were independent, whether they had signs of dementia, et cetera, et cetera. So if the patient came from a nursing home, because she'd been there for five or 10 years, the answer is probably no. But if the patient had been living independently up until about a year or 12 months ago, you know, then, you know, after proper discussions, then yes.

- Okay. Thank you. And that's exactly was in her case, and I'm just going to go ahead and briefly review this last video with you. This was the last frontal tumor. Again, it was in her lumbar drain, opening the dural, devascularizing the the tumor. This is a rather classic, you know, meningioma. I think most of the folks do it this way. Anything special about resection of such big tumors in this area, Mike?

- I think this one's, you know, pretty safe. I mean, it's faulting more than parasagittal looks like. So, but in her case, I wouldn't be terribly aggressive about trying to excite the falx. You know, I'd want to debulk the tumor and to see what's safe. Limit the length of the operation, and, you know, except the Simpson for resection, meaning the big lump on the right hand, and if the falx is a little bit thicker, that's fine.

- And any complications that you have seen with resection of these that has been unexpected that you want to warn people to watch? I, I know you talked about intradeployed veins. Any other complications that can be problematic?

- Well, just that, you know, there's no safe zone of the superior sagittal sinus, if there's, if there's involvement there. So you can't routinely even sacrifice a leg at the anterior one-third, because periodically you'll get stumped, the patient will be hurt. So I just to keep that in mind. In our published series of over 800 meningiomas, the incidence of major medical complications was 6% and the incidence of venous infarction was 2% with the mortality of 0.2%. So in the modern area, era, things are, you know, pretty good for the patients. And as long as we don't create an injury, I think we should expect reasonable outcomes.

- Thank you. And here is, I guess the point I was trying, trying to illustrate in terms of using the carotenoids to hold the brain out of the harm's way, and sort of advance them slowly as you debulk the tumor. And so it really creates a nice plane and also cover the brain as you get deeper and deeper as a protection layer. Any thoughts about how you would have done this?

- No, same technique. I use a different type of carotenoid, which I find less adherent, but, you know, and cover the surface of the brain with, with cut Biogel glove as opposed to using tempo. But the same principles, you know, debulk, pull the tumor away from the brain. Don't pull the brain away from the tumor.

- All Right. And after a while, you're going to find yourself in a carotenoid tumor. You just replaced the tumor with carotenoid oedema and ultimately, obviously, carefully respecting the vasculature as you, as you very well mentioned, Mike. So let's go ahead and finish our discussion with just, this is a postop MRI on that lady. The closing obviously, we use a dural graft. Do you have any special preference in terms of closure techniques, Mike?

- No. Just, I noticed on one of your rep, the middle third parasagittal tumor that was bilateral. If you ever have to excise the convexity dural along the midline and both sides, sometimes what I do is, I build up a little carotenoid template to mimic the surface of the brain, and make sure that my dural patch is a little bit on the redundant side, because if you just take a small piece of dural substitute and suture again, on your postoperative coronal scan, you're going to end up with an epidural fluid collection.

- Okay.

- And then if the patient has any deficit, people are always going to have to wonder about whether that fluid collection is significant.

- Yes.

- So we create that redundancy in the dural flap and we can tack it up even right up to the midline like we routinely do. And then you don't have these epidural collections. So that's a little trick that I've, I've learned, but, you know, I don't, I don't think it matters whether it's bovine or porcine dural substitute. We, we tend to try and use something that's water impermeable, and that can include the pericranium, which is a great donor source for rest of these large defects.

- Thank you. So in closure let's just briefly review some of the pearls and pitfalls just like we have done for the other sessions. Is that for these tumors manage intracranial tension well, obviously you don't want to brain to come at you before you reach the tumor and make things complicated. Seizure prophylaxis as you mentioned, Mike, if there's no seizures preoperatively, seven days of seizure prophylaxis, weaning them off afterwards. If they have a seizure, I assume you keep them on six months to a year. Is that correct?

- Yeah, six months.

- Six months, and then slowly wean them off if you haven't, if they have, if they haven't had any more seizures.

- Correct.

- Choose your incisions wisely. Conduct the last osteotomy with the sinus, I think that's pretty obvious. A lot of respect for the cortical veins. Devascularize early. Manage your blood loss carefully, have a handle on it, and handle the brain gently. Watch for the arterial blanche, especially in this category of tumors for pericallosal arteries. High index of suspicion for air embolism. And for patients who have a partial thrombosis of the sinus, don't be aggressive to reconstruct the sinus and remove it. I think that is fraught with complications. If the sinus is partially patent, leave it alone, be conservative, there is radiosurgery, there is other ways to treat it. Being a hero does not usually pay off in these circumstances. And especially in younger patients try to resect in both segment of the falx. And the bilateral parafalcine meningiomas usually can be resected through unilateral craniotomy. Coagulate the edges for the better Simpson grade, and clear the resection cavity at all times for better planes of resection. Any other final thoughts, Mike?

- No, just to take advantage of displaying the MR venogram on your image-guided system. Don't be afraid to use the intraoperative Doppler, either the ultrasound Doppler, the handheld Doppler to assist you with determining patency of venous structures.

- Okay. Mike, I want to sincerely thank you for your great expert opinion. I think your expertise added a significant new layer of thought process and wisdom here, which I think all of our viewers, including myself have enjoyed. I appreciate your input again. And we look forward to having you with us for the next session. Thank you.

- Thank you, Aaron for inviting me.

- Thank you.

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