Grand Rounds-Evaluation and Operative Management of Pediatric Moya-Moya Disease

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- Requirement Bayer from the University of Michigan, and it's my pleasure to welcome our viewers to another installment of WNS Operative Grand Rounds. The speaker today will be Dr. Ed Smith from Harvard Medical School. Ed is the director of cerebral vascular surgery at Children's Hospital Boston, where he directs certainly one of the largest and most well-respected Moyamoya programs in the entire world. Moyamoya disease will be our topic today. So it's a again, Ed, it's a real privilege to have you join us today for Operative Grand Rounds, and thanks for being here.

- Well, thank you Cormac. It's a real honor to be here. I appreciate the flattery. I do want to acknowledge my mentor, Mike Scott, and I look forward to talking a little bit about pediatric Moyamoya, both the clinical presentation, and also some thoughts on operative management. I have no real disclosures to make, and I thought I would start off by talking a little bit about the background of Moyamoya. You know, as most folks know, Moyamoya is a very rare condition. It's sort of characterized by progressive narrowing of the internal carotid arteries and their associated branches, the anterior cerebrals and middle celebrals. The course of progression is very variable. In some kids, it's very rapid and can be very fulminant, in other kids, it can be very slow, but generally, it is a progressive disease. It was first described in 1957 and then the name itself, which means puff of smoke in Japanese, based on how it looks on an arteriogram, it was described by Suzuki in 1969. And one thing which I'll talk about a little bit, and I think is worth knowing, is this difference between Moyamoya disease, which is the sort of classic bilateral Moyamoya arteriopathy with no other associated conditions, and Moyamoya syndrome, which is the arteriopathy either unilateral or bilateral, often with another associated disease. Just in terms of background, some things to know. Moyamoya affects all ages, but has sort of two well-known peaks, young kids sort of five-year-old preschool kids, and then young adults, 40 years old. It's more commonly present in females, and it tends to be more commonly described in those of East Asian ancestry, such as Japanese, Chinese, Korean, although, while it's described as about as one in a million in the United States, it actually seems to be increasingly more common and that may be due to increased diagnoses. As you might expect in disease, predominantly affecting Asian ancestry, it is seen more commonly in folks of Asian ancestry in the United States about twice as much as it's seen in those of African-American ancestry. And we'll talk a little bit about some thoughts there with sickle cell disease, and less so in of Hispanic ancestry. And the diagnosis, there are formal guidelines from the Japanese literature and the International Classification of Diseases, but basically it's made on clinical and radiographic findings with very characteristic findings of narrowing in the internal carotids. And so this is a little cartoon here showing some of the things that you can see in Moyamoya disease. Basically, what you have here is state, and no disease, here is the lateral projection of the internal carotid that you see here, and it has a very normal branches extending into the brain. The Suzuki staging system, sort of one through six, describes this progressive narrowing and the development of these characteristic collateral vessels. So Suzuki I or II, for example, you'll see here, there's this area of narrowing with poor profusion on the brain, but the rest of the vessels are present, they're just narrowed. And then down here in the corner, you can see the very classic Moyamoya. The so-called puff of smoke. These are the collateral vessels. This is Suzuki III or IV. And what these are a combination, we think, of normal vessels that have dilated and also new vessels that are growing in response to the ischemic brain. So this is sort of the classic finding. And then lastly is the stage V and VI where the carotid so narrows, that there's really no blood supply to the brain. And the unfortunate result of this is you'll get a stroke where you can see here, for example, where the consequence, unfortunately, of Moyamoya is a stroke. Now, thankfully there are, you know, findings that help to explain some of this. These are some pathology sections from one of our papers. These are cross-sectional pictures of the carotid artery. And what you can see is that with Moyamoya, what makes it different from other diseases of the vessels is this overgrowth of the smooth muscle cells. And so that narrows the artery and what you have is this very tiny lumen you can see right here and that's really what's supplying the downstream brain. And that explains why these kids, we think, are so sensitive to changes in blood pressure. If they get dehydrated, if they hyperventilate and they have vasoconstriction, or if they have thrombotic conditions or they get dehydrated with promise, which can seal it up, you can see these little plots of thrombus inside the vessels here, and the consequence of that, of course, is that they can get transient ischemic attacks, or in more severe cases, stroke. And that's why it's so important to keep these kids hydrated, make sure they don't hyperventilate, if you can help it. And also to make sure that they get aspirin, which we think is helpful in managing these diseases. So, you know, what we think about next in terms of these kids is really the question, you know, is all Moyamoya the same? You know, are kids the same as adults? And I would suggest, I think this is a picture of Dr. Mar as a younger gentleman, that kids are not just little adults. There are some unique aspects to pediatric Moyamoya, which I think distinguish it from the adult population. Presentation, how they are diagnosed, peri-operative management, operative techniques, a little bit of how their outcome is like, and then maybe talking a little bit what to do going forward. I think, Cormac, as you know, I think you see an awful lot of these kids, how they present is very important. At the Children's in Boston and in many other places, most of the time, these kids seem to present with ischemic symptoms. Either they have a stroke, or they have transient ischemic attacks. And I know one of the things that comes up often when people say, "Well, gee, "could it be that these kids present with hemorrhage." It is extremely rare to have hemorrhage in kids. And it's about a seven-fold less common presentation than adults, but even for adults, the majority of presentations tend to be ischemic and not hemorrhagic. So just talking a little bit about the presentation of Moyamoya. There are a lot of different ways that Moyamoya can present. So for example, they can present with strokes, most commonly with ischemic symptoms. Cormac, you may see this often with your kids as well. And the rate of hemorrhage is really much less in kids, than in adults, about seven times less or so. Now one of the things that I think is very commonly a big debate and Cormac, you may do this differently in your institution than here, is how one does the diagnosis of these kids. Now, Cormac, how do you normally work your kids up for diagnosis in Michigan?

- For us, it's typically first diagnosed as you're showing here with MRI, and there's, I'm sure as you're going to talk about, some very characteristic MRI appearances of Moyamoya disease. And then we proceed with the angiogram. And in every case, if I'm going to treat a child with Moyamoya disease, I'll order an angiogram, a conventional angiogram. But I have to say some of the recent data that we've all seen on the dangers of radiation in childhood has caused me to second-guess that a little bit. I think for me, I've always got the angiograms preoperatively, and I think I'm going to continue to do that. I've also always done angiograms a year post-operatively, and I think that's where I'm questioning the utility of conventional angiography now to perhaps get fewer postoperative angiograms than we've done in the past with substituting a lot more MRI angiography, just to try to avoid the radiation risk in children. But, just like you suggest on this slide here, Ed, I think we've always done the MRIs. We've always done the angiograms preoperatively. That probably won't change, but I think we might be doing fewer postop angiograms in the future.

- I agree with you, Cormac. It's something that we're leaning towards a little bit, as you can see here, we typically get an MRI at the beginning. One of the big debatable questions that I hear a lot, and I wonder and struggle with a little bit, is how do you know if the kid has active Moyamoya just versus in arteriopathy. We lean as, as you probably know, pretty heavily on this idea of flare changes, the so-called IV sign. You can see here on the study, these bright white signals that exist in the south side of the brain, and we use this as a marker of slow flow. It can be a false positive sometimes if the kids have been sedated, for example, on propofol, but that tends to be bilateral in finding. Whereas, if it's unilateral or different patchy focal areas, we tend to think that's more commonly indicative of ischemia. In terms of your question about the angiography, we still continue to get them on most kids, but some of the kids that are more complicated medically, sickle cell kids, some of the very young children, six months of age or so, we may avoid it if we're very confident in the diagnosis. And you know, the other thing is frankly, some kids with insurance problems, it can be difficult to get the arteriogram done. I don't know what your experience has been up there.

- Yeah, we've had no issues with having insurance pay for the arteriogram. We've had some trouble with getting insurance companies to pay for the old practice of bringing patients in for hydration before procedures with Moyamoya, where they're admitted the night before. Is that still the practice in Boston?

- Yeah. And I'll talk about that maybe in a moment with some of our preoperative management, but that's a very common practice here, and I think it's been helped quite a bit. One thing we do do in terms of our diagnostic evaluation early on, is we start the kids on aspirin. And again, that's sort of a debatable point by some institutions. We think that it helps, as I showed in the earlier slide, with this idea of reducing thrombotic complications, and we keep them on the aspirin right up to the day before surgery, and we restart it the day after surgery. I don't know what the you folks do.

- And you treat every child with Moyamoya with aspirin?

- Pretty much. There are a small number where they've come to us already on a different antithrombotic agent, or an anticlotting agent. They may be on heparin or . But if we can, we try to transition them all to aspirin, just for ease of use and because of familiarity with its application.

- What kind of a dose would you typically use in a child who's relatively asymptomatic, perhaps presented with a TIA?

- Yeah. Most of about 81 milligrams once a day, and sometimes we'll double it up if they're having an active spell. I don't know if that's what you do, but that's pretty commonly what we do.

- Yeah. That's little bit more than, than we do here. And would you keep that child on aspirin indefinitely or is there an end point to that treatment?

- So far, forever. You know, the general thought is that the side effects are usually pretty low at the lower doses. They often don't have bruising or stomach upset, and unless they have an allergy or they have aspirin intolerance, you know, we usually keep them on it. And you know, you can see here in this next slide, if I can just skip ahead here for a second. You know, one of the key things that I mentioned a little bit about this is this idea of multidisciplinary consultation. We've seen, I know you've seen, and a number of other groups have described Moyamoya, obviously not just in its sort of pure disease form, but in association with other conditions. And I think it's important, and one thing that's a key dimension for neurosurgeons are to act as a sort of evangelists for Moyamoya. One of the earlier slides commented on, you know, it's a one in a million disease in the US. I think you and I, probably, we've talked about this before and many other folks believe it's probably a lot more common than that. I think part of that is that it's under recognized and you can see here, if you look at these different groups, this is from one of our papers, you know, you can see it with neurofibromatosis type 1, down syndrome, people have had radiation for brain tumors, sickle cell disease, I think is a huge population. And I think that it's very important to consider this because these kids may have strokes that are being attributed to other conditions, and in reality, they may have this arteriography, it's a minimal of surgical therapy. So I don't know what you think about that, Cormac.

- I think that was a great paper that you published in, I believe it was stroke, right?

- Yeah.

- But- And this paper really points out the problem with this one in a million estimate, because here you've got an 'n' for idiopathic disease of 66 and you've got a large 'n' of the associated conditions as well. And again, there's about 75 million children in America. So if you do the math, all of a sudden, even just the people that you're treating gets us up to the estimated incidents in America. And obviously people are occasionally treated at other centers as well. So the incidents estimates that we've been seeing in the textbooks must be far too low, I think.

- I agree. And we've talked about this before, and I think it's really important as a neurosurgeon to try to advocate for that. I think some of the big areas where we're, you know, we've talked about this, other people have talked about this, are these syndromic associations, you know. And in particular, neurofibromatosis type 1, you know, these are kids that are in the hospital for brain tumors, are in the hospital for their systemic problems and having a relationship with the NF clinic, you know, to identify people at risk for what might be TIA is a great way to help these kids. Down syndrome, you know, depending on their level of potential cognitive impairment, can really sometimes be a problem to identify this, especially because the down syndrome kids many times have cardiac anomalies and they'll attribute the stroke to a heart problem, when in the back may be Moyamoya. And then lastly, kids who have cardiac anomalies in general without the down syndrome, there is an association with Moyamoya. The recent letter literature on, for example, ACTA2 mutations, where there are these multiple systemic vascular disorders, and they may also have Moyamoya. So things to think about and I think important to be able to communicate that to other members in your hospital. One of the things that I think is probably one of the most important syndromic associations is this sickle cell disease. And, you know, this is increasingly becoming something that's being made aware of. I've talked to a lot of colleagues as you have around the country. People have had the STOP trial where they use transcranial Doppler to identify people with elevated flows based on transcranial Doppler in their cerebral vasculature. If they find them, they know they're at risk of stroke and they start an exchange transfusion, and that reduces the risk of stroke in many kids, but there are small number about 10% or so, that will continue to have strokes, even getting, you know, exchange transfusions. And these are the kids that, you know, more and more imaging studies, I think, are revealing that they really have, you know, essentially an arteriopathy, it looks like Moyamoya. And so I think these are great kids that respond very well to therapy. And we've got a special protocol we use for this with exchange transfusions ahead of time, making sure that we involve hematology, timing, pain control, things like that. And I'd be curious to hear what you folks do for your management for sickle cell kids with Moyamoya.

- I'm glad you highlighted sickle cell disease. And I think it's really the gray area right now, where we're seeing a lot of undiagnosed cases of Moyamoya disease. Kids who are having strokes that definitely have Moyamoya, evidence of Moyamoya syndrome and are not diagnosed. The hematologists that are managing them don't feel comfortable with the idea of brain surgery and will persist with medical management, even in the face of stroke. So it's been my experience that there's really a lot of resistance to the idea of the surgeries that you're going to talk about in the hematological communities. And I think this is an area where there just has to be a lot more education and a lot more research done, a lot more talking about the kind of benefits people can get from these sorts of operations.

- I think you're right on the money, Cormack, and you know, and what that leads into, in addition to the diagnostic side of things, is, you know, once you've made a diagnosis, how do you- When do you operate? You know, that's, that's a huge question. You talk about that with the hematologists, you know, I'm from Massachusetts, we're a liberal, a blue state. It's a little blue state rules here, but I think that with Moyamoya, we've always sort of adopted a very sort of almost aggressive policy in surgical management. If there is radiographic evidence of disease, particularly if it's associated with those flare changes, that IB sign we talked about, we generally will advocate for surgical intervention. The kids need to be stable for the operating room. So they've had a recent big stroke, we may wait a month or so. And the other time we may hold back is if we're unclear of the diagnosis, or if it's a very early time in the disease, those kids, we may hold off and watch every six months or so with an imaging study like NMR, because we think that, number one, they may or may not progress. And if they do, the angiogenic drive, we think helps our surgery to work so well, works better if we can get them when they're sort of cresting in their sort of ischemic period. I don't know how you folks manage things out there.

- Just the very same, because I was trained by Dr. Scott and learned from him a lot of these same rules that you're stating here, but I think that's right. I think the real question is when to operate in the early stages of the disease, and the major dilemma is really not that you should operate on Moyamoya, it's is it really Moyamoya? And when you're presenting with a Suzuki I, you're just never sure. And so you just have to wait on those, but I think for us right now at this hospital, if we can be certain that we're dealing with Moyamoya, will recommend surgery.

- Great. So once we've sort of recommended surgery, one of the big questions that come up is, you know, how do you treat the kids? And this is relevant, I think from, you know, the colleagues you talk to in the hospital, for other members of your department that may ask how you treat the kids, and certainly for the residents and the fellows, you know, what do you do with them? You know, we generally, from a medical standpoint, that's the first set of questions that comes up are very anti, really no role for the use of steroids, I don't think. The anticoagulants, we talked a little bit about before, again, not a first-line treatment in general because of the complications in general and managing them, their needles are not... I don't think it's efficacious where it's more of a thrombotic problem. We do like anti-platelet agents, particularly aspirin, like I mentioned, and we discussed just a moment ago. And then one of the real controversial areas is this use of calcium channel blockers, where the thought is, it may help a little bit with the management of headaches, possibly even TIAs, but obviously, the risk is if overused, or if there's a idiosyncratic reaction, it can drop the blood pressure, and that's clearly bad for someone with a sort of a occlusive cerebral vascular disease. So we tend to be very hesitant of that, but it is something we have in place from time to time for kids with refractory headaches. Have you had any experience with using that at all?

- No. We haven't used calcium channel blockers. I think of any of the items on this list, we really only be using aspirin. And just as you suggested, I really don't see a role for steroids or for anticoagulants. Aspirin, I use. Calcium channel blockers, not at all.

- Yeah. Well, I would agree. We tend to use the aspirin and as I showed you earlier, we have this very sort of regulated peri-operative management protocol we alluded a little earlier. I think we were talking to two sort of important points. One is it's a big deal, I think, that we admit the kids to the hospital the night before. The rationale is we can give them intravenous fluids. And in very simplistic terms, the idea is you tank the kids up. And if they're NPO for anesthesia, you hopefully reduce the risk of their pressure bottoming out during induction, which we think is a big risk window for them with the surgical intervention. The other thing we do is we keep them on aspirin right up to the day before surgery. They get their dose the day before surgery, we restart the day after surgery. And then during their hospital stay, we run them very aggressively on fluids, one and a quarter to one and a half maintenance. We interoperably have a number of steps we use such as a precordial Doppler, interoperative EEG, which helps the management. I know that's a controversial point. And then postoperatively, in addition to the fluids and the aspirin, along with blood pressure control, we really try to make a point of managing your pain and anxiety because these kids can be very fragile. They can cry if they hyperventilate, or if they're vomiting a lot. The problem is they can unfortunately, you know, get a stroke from that. And so those are some steps we take in terms of managing these kids perioperatively. In terms of the surgery itself, and I know you know this, but driving in Boston is pretty bad. And, you know, coming from Boston, if you're trying to get from the Cape up to New Hampshire, for example, you can go by one highway through the city or another outside, and sort of as a general review of surgical options, before we wade into the debate, you can do a direct or indirect bypass, but basically if the carotid is narrowed per Moyamoya, we will try to use an external branch of some sort of vascularized tissue, commonly a branch of the superficial temporal artery, but it could be muscle, it could be pericranium. There's a lot of other options, but the idea is you bypass the quad here to get where you want to go. And, you know, it's probably worth having a little debate about this, but in general, you know, there's two big types of approaches. There's direct where you can take a blood vessel, basically cut it in half and you can sew it directly into a vessel into the brain. The benefit is you get immediate perfusion of the brain, but it can be technically challenging and requires some clamping time. There's also the risk of reprofusion injury. Indirect, and these percentages are from a big analysis from following a meta analysis from 2005, the biggest shortcomings it takes weeks or months for the blood vessels to grow. So you have limited, if any, protection during that time, but it is an easier surgery. There's no clamping time and you can potentially have a big, broader area of revascularization. So this is a huge debate that comes up a lot. You know, I don't pretend that there's any right answer. As you know, we tend to use indirect pretty heavily here at Children's, but other institutions very heavily use direct. You know, and it's a big debate, it's something that comes up a lot.

- My perception is the children's hospitals have almost all moved in the indirect direction. I don't think I know of any large pediatric practices that are doing mostly direct. Is that your impression as well?

- Well, there are a number, you know. I think Gary Steinberg at Stanford has a very active, direct practice and it gets wonderful results in his hands. You know, a number of other folks feel that the direct surgery is something that works pretty well, especially in the older or the teenage kids. So I think it's at least, what I've heard about, it's a reactive and ongoing debate. That said, you know, I think we've been very happy with the results we've had here. You know, Mike Scott, who I want to acknowledge, is my mentor here, has really developed a technique we use at Children's, which I'll review briefly, but this operative technique we use is pial synagiosis. It's essentially a variant of EDAS where the two big differences, I think, are sewing the vessel, the branch of the superficial temporary, the parietal branch, right to the surface of the brain. And the idea there is it sort of keeps the blood vessel on apposition to the brain so that you don't have this gap. So it's harder for new collateral vessels to grow. And then the other, and I think this is really an important part, is this wide arachnoidal opening. And I think this benefits any type of revascularization surgery. If the premise is that all these growth factors that exist either in the spinal fluid or in the basement membrane of the brain itself, actually get in contact with your donor sites and it stimulates growth. So I think that's something that we're big fans of, intend to use as a key component. You know, and do you do similar, sort of a wider arachnoidal opening for your bypasses out there?

- Absolutely. I've been trained under Dr. Scott, essentially try to mimic that operation exactly. It seems like the obvious best operation right now for Moyamoya, at least, least in my hands. And so that's very much what I would do as well.

- Well, what I thought, you know, maybe we- There's a video, I think, of the way we do this operation, it shows some general principles. We might try to get that started up here to take a look at the video itself. This is just a little bit of an overview. The general idea is that you take a branch of the parietal superficial temporal artery, you lay it on the brain to get growth. We have a set table setup that we use here with all the appropriate equipment. We use normal saws for retraction. We have set microdissection tools. We use a Doppler to map out the course of the superficial temporal artery, and we use EEG to help us monitor the patients during the case. This is the way the EEG montage is laid on, so it's not in the way of our draft mapping out the STA here prior to surgery. And then we start directly under the microscope, starting distally, as you can see here, and then working our way proximally to reduce the risk of injury of the stem of the vessel, just with a Jakes and a 15 blade. And this allows us to go along the course, these side branches, we dissect, and we try and leave a little stump because I think that's an area where regrowth of new vessels occurs pretty well, as opposed to just if you take it right up to the edge of the vessel. We leave this cuff of tissue around the vessel, which I think is also important. You don't denude the vessel like you would for direct bypass. Again, this is sort of a substrate for new vessels to grow in, and that's both on the sides. And as you can see here in the video from below the vessel, as well as it comes off the temporalis, and then we create this big plane between the galea and the temporalis muscles, big as possible, hold it back with these retractors. We divide the temporalis muscle into quadrants to get the biggest space we can. Obviously, the bigger space you have, the more revascularization is possible. We do Burr holes at the base and the apex of the artery, and turn a craniotomy flap, and then open the dura in about six pie-shaped wedges. Again, the idea here is both to get the most exposure possible, but also each edge of dura can be in a separate source of vascularization from the middle meningeal artery. This is our setup where we can see the case, both with the EEG and also with the imaging during the case. The EEG is really important for real time monitoring. And then as I mentioned, this is a key part, I think; opening the arachnoid. You know, Mike Scott really promoted this, and this removes this mechanical barrier to in-growth, but also, I think, promotes the communication of all these growth factors from the spinal fluid. We use Iris scissors, we use jeweler forceps. There's a lot of different ways to get the area open, and along the arteries and veins are helpful. And then hopefully you can open it over the brain. Some of the really injected brains with big collaterals are tough. And then as you can see right here, once we have the vessel ready, we try to put, you know, about four or so sutures holding it to the surface of the brain. We use a 10-0 nylon on a BV needle. So it's a real tiny needle, you just go just under the peel surface. like you can see here. And hopefully the concept is, is that, like I mentioned, this folds this in contact with the brain and all that substrate on the undersurface of the vessel, you see us pulling on the imaging here. It helps to, I think, create this new network of vessels from the STA donor to the brain itself. We tie them down and once they're in place, the hope is that, you know, this will keep it there, even when you replace the bone flap. Now real contested point is after we've inspected the suture sites, make sure he's good, we just put the dural leaflets back on. We don't sew them. There's no watertight closure. And we just put a piece of gelfoam on top. So you can see the dura helps new blood vessels grow. We just put the gelfoam on. Then we replace the bone flap and then close the temporalis muscle in the horizontal plane. And that's really about it. The hope here is that this stimulates a lot of growth for the vessel. And as you can see, we use resorbable sutures. So they don't have to come out of the kid's head after and they don't cry, we hope. And then this is what we hope will end up happening, conceptually. And then as we see on the postoperative imaging, so that's a little run through of how we do the surgery here. I'm not sure Cormack, exactly, if you've got variants now that you've been sort of doing your own thing for a while now.

- Obviously learning from Dr. Scott, I try to do the very same thing that you just showed in that incredible video. One variant, which I'm sure you've seen as well, is sometimes you open up the head and you see a huge middle meningeal going right down the middle of where you had intended to open the dura. And at least for me, I've started to try to leave a pedicle of dura with the middle meningeal going down the middle in those instances, and then adapting the dural opening with the pie-shaped openings out to the side of that. Is that something that you do as well?

- Yeah. I mean, it depends how big the artery is. Certainly, I think as we just mentioned, the preoperative arteriogram is really helpful in this. If we see that there are collateral vessels that sort of supply the brain from the middle meningeal, which you can tell with an external carotid injection, then that is no man's land, and the hope is you preserve that. You know, one of the other sort of technical points, I think, is on the opening, you have to be careful of where the middle meningeal or branch comes through, you know, around either the bony openings or sometimes around the sphenoid. And so planning your bony opening and being careful can be really important to, I think, complication reduction. I don't know what you think about that.

- Yeah, absolutely. And certainly when the middle meningeal is providing collaterals already, as you say, no, man's land, you don't want to touch that vessel. It's just going to cause a stroke. But even in cases where I don't see the collateral, sometimes when the STA goes into spasm, especially if it seems like the preserve middle meningeal can almost be the same size. And to me, it just seems to make sense that two vessels is better than one.

- Yeah.

- But absolutely. And it doesn't come up very often. Usually it's often one side or the other.

- Yeah. And so, you know, that's, I think, what we use most commonly at Children's as you know, and as many other people do, one of the other options is a direct bypass. And you know, there's a little short video. I think we have of this as well. I don't know if we can tee that up here for just a second, but the direct bypass is an alternative. I think we use it infrequently here. We do use it again. Here's a little example of the same table setup, where we have everything standardized and ready with the same tools. So this is the video here for a direct bypass. And basically, just like before, we do the artery the same way. What's different is we give some IV heparin. We try to protect the brain with a rubber dam. We clip the artery proximally, and then different from the indirect, we strip the- Sort of right down to the adventitia. We bevel the tip to make sure we have a wide mouth. We fishmouth the graft site, like you can see here, to make as wide and opening as possible. It gives you a heel and a toe, and inking the end, I think, really helps it to be seen better. We get a good temporal branch just 'cause the temporal lobe is often more forgiving. We will open up a little side window in the vessel, ink it as well, saw in the heel and the toe of the same 10-O nylon, and then just do a direct bypass either with multiple interrupted or running, depending on the size. And we use the ICG dye and you can see here, the good flow through the vessel, indicating that the graph has paint in, it fills the brain. Sometimes it will bleed a little bit at the donor site, recipient site, and usually that just stops with a little bit of gelfoam. And then as you can see, we close at exactly the same, there's really no difference, I think, at the end of the operation from a POS angiosis, other than there's no vessel coming out from the top. So that part's the same, but what's different is how you prepare the artery, and obviously the direct bypass itself.

- What's your indication of choosing a direct bypass in a child?

- So in general, it's pretty rare. Before we can even consider it, we have to make sure that the their artery is big enough, and that's a very subjective finding. I would say that the sort of clinical indication would be up to having multiple stuttering TIAs or multiple stuttering strokes. The problem is that the most common population, at least that I've seen like that, are the kids under age two. And frankly, I think their vessels, at least in my hands, are too tiny to reliably do those bypasses. So the kids that you want the immediate direct reprofusion, I think those are the ones where the direct bypass might be indicated. But unfortunately, that population is often anatomically the most difficult. I don't know what your situation's been like.

- Absolutely. For us here, we tend to do indirect bypasses on the children and direct bypasses on the adults. And as you know, there's really not a lot of data that's out there in the literature right now to guide our practices in terms of choosing one operation to the other. And my feeling has been that unless somebody can provide evidence that the direct operation has a better result, you should do what is obviously the safer operation, which in my hands, is the indirect bypass.

- Yeah. Again, an area of big debate, but I agree with you. I think a lot of it is surgeon's skill and familiarity and in my hands as well. I tend to think that the results for the POS angiosis, and certainly in Dr. Scott's hands and others who've done it quite a bit, seems to work extremely well. One little technical point we mentioned briefly, I think, is a big help, but for pediatric patients in particular, this idea of using resorbable sutures, there's just a little video here of a kid, you know, sort of what the incision looks like, but this idea of not having to bring the kids back and take out their nylons a week or two after surgery and have them screaming and crying, and the parents have a separate visit to the hospital, I think is a big help. We tend to use, for example, a or a monocryl. Do you use a similar suture? What do you use for your closures?

- rapide as well? Exactly.

- Yeah. So yeah, the last question a lot of people ask is, "So Eddie, you know, you do all these surgeries, "how the kids do, you know, what happens when they go home?" I think our results are probably pretty typical for what most folks have that, you know, see a lot of these kids. Radiographically, the kids tend to do really well, their Matsushima grade, which is essentially a way to look at the lateral arterial gram and get a sense of how much of the middle cerebral territory is filling, you know, less than a third or less, one third to two thirds and greater than two-thirds. Basically in our hands, about 65% are grade As, about 25% are grade Bs, and about 10% are grade Cs. This holds true, even for the very young kids under age two. People ask, are they biologically different? I think they work out pretty well the same. In terms of clinical outcomes at least again, from our experience here, they do very well. You'll get the rank in scores, about 98% are stable or improved. And that's against the setting of the Moyamoya arteriopathy, and about 65 to 75% getting worse over five years. So even though the arteries get worse, the clinical results get better and that's nice to see. The most important thing obviously is the stroke rate. Our series, both with Dr. Scott and more so now that we have some my own to follow-up over time, we get about a four and a half, 4% rate over five years. The biggest stroke risk seems to be in the first window after the peri-operative period and the first couple of months thereafter. And then the younger kids under age two, they have a higher peri-operative stroke rate, at least, you know, my experience has been they're much more fragile, but if you can get them through their operation successfully, they tend to do really well. And their long-term stroke rate is almost the exact same as the older kids. So I think that suggests that it works pretty well. You know... Cormac, I don't know what you... What do you tell your families before you see them in the, in the office?

- grade in the very young children reflects the fact that they have worse disease, they're presenting at a younger age with more advanced disease state. Therefore, what we're seeing, to some extent, in the post-operative outcomes, I think just reflects a worst natural history as well, because we don't change the natural history right away with this operation. It takes time as you know.

- Yeah. Yeah. And also I think they get in this sort of catch 22, where they have a stroke, whether there's sort of bad inflammatory stuff that's released into the CSF, whether the brain is swollen, you know, they're fragile. And then that begets another stroke. And I think you get in this sort of chasing your tail phenomenon. And I think at some point, you just have to sort of face things and take care of the problem by revascularizing them, even though many times, the tendencies to wait things out and let them cool down, it's always a difficult topic, I think, to know what the right thing is to do. In terms of what we see, you know, what we're looking for. We follow all the kids with our arteriograms at one year. So our policy generally is an MRI at six months, in arteriogram at one year, although we talked a little bit about how that's something in evolution now pending on the kid's age, their prolixity and, and frankly, their insurance a little bit. We prefer the arteriography if we can. We look for this sort of growth here, refilling the unvascularized or devascularized area, and then we follow them longitudinally looking for strokes over time. We get an MRI every year for five years, and then roughly every two years thereafter. So that's a little bit of our follow-up protocol. And then before I start to get into yours, you know, we keep them on aspirin forever. We don't really restrict them. We have a number of kids now that have grown up. For women in particular, they get pregnant, they have kids of their own, you know, they do pretty well. And with a population of about 147 kids who have 10 years of follow-up, the stroke rate stays about the same. It's about a percentage point higher at 10 years out. So it's durable. I think the surgery works. They will sometimes get a TIA usually in the first year or so, but it works pretty well. And that's sort of what I tell the patients and the families. What do you do Cormac for restricting your kids for sports or activities, or in terms of, you know, talking about long-term lifestyle outcomes?

- Well, in general, I tend to be pretty liberal in terms of my restrictions for kids. And just as a sort of a general principle that applies to Moyamoya as well. I have to say for the first couple of years after surgery, I don't feel very good about them participating in really high impact activities and the kind of thing where they could hyperventilate and that sort of thing. Having said that, the population that I'm operating on is generally pretty young and these are not kids for the most part that are participating in sports at a high level. So I haven't found that that's a significant restriction for the most part.

- Yeah. I agree with that completely. I mean, I think we're doing very similar things here, but I do tell families that while they will always have Moyamoya, the disease is always there. Similarly, they tend to have great long-term outcomes if they can be revascularized.

- outcomes from that study from Asia a couple of years ago really reinforces, I think, the data that you show from Boston too. It's, I think, wonderful news for this patient population. For a long time, we didn't know what the long-term outcomes were going to be. We knew they did okay in the short term, but what is their life really going to be like? And I think now based on the data from Boston that you're showing as well as some of the data we've seen from the Asian centers, we can say, you know, the life is actually going to be pretty good. Your expectations for normal life should be pretty high.

- That's the hope. And so just to give a little example here, what we look for, you know, we get these MRI MRAs, and this example pre-op is here on the left and post-ops on the right. And I think this highlights a couple of important things. I mean, first off, I think what you can see is that pre-op, you know, you have the bad disease here, post-up, the disease progressed to both sides, and pre-op, you have all this flare changes, IB signs, bright signal on the south side and post-op, it pretty much has all gone away. So these are pretty good indications. I think that things get better with time. You can kind of see what these little arrows that are up there, you know, that we get good ingrowth. And this is I think, a testament to how well the MRIs are doing now and helping us to see these collateral vessels surgically that we're developing. And my hope is we can, as you mentioned, get a little bit more away from arteriograms, although they're very low risk and not no risk, and they're certainly less risk, more risk than MR. And then this idea of the IB sign going away, I think is really a good finding. You do need to follow these kids though. You know, this is a kid, a younger kid. Had a relatively normal looking vessel on the right, a little wimpier A1-ish, you know, really not there. And then in several months, this just rapidly progressed. You started to have these proliferative vessels as narrowing here. And at least in our experience, these risk factors, if they're younger kids, so under age seven, if they have any arterial graphic abnormalities, you know, these are kids we tend to watch pretty carefully with MRIs every six months or so, because we look for this kind of progression. Have you had that sort of experience, Cormac, with your unilateral cases?

- Again, it's based on the Boston experience and your experience and Dr. Scott's experience, but absolutely if you have unilateral Moyamoya disease, you have to be on the lookout for this to turn bilateral. And that's the expectation more often than not.

- Yeah, I think it's really key, I think, to engage the families and explaining that the surgery is not the end of the story, especially for unilateral or for even the bilateral patients, because they do need careful monitoring. You know, if they have any graph failure, which is very low, it's only a couple of percentage points, but it's it's enough that it merits watching. And I think these need to be lifelong patients. I tell them, it's kind of like a day of diabetes or hypertension. Hopefully, they can go about their daily activities pretty well, but they do need to maintain that relationship, hopefully lifelong with their docs. You know, to sort of wrap up the discussion here, I think pediatric Moyamoya patients, I think, are really... They do have some important characteristics that are different than adults. I think being aware of syndromic cases, especially as we discussed, the sickle cell population, the kids that may have cognitive problems or other masking medical conditions, Down syndrome, neurofibromatosis, and that's something as neurosurgeons, I think, you know, you and I, and all of us that see kids with this have a real role in getting into. The surgical indications are really debatable, but I think there can be a very strong case to be very aggressive in managing them. And then preoperative hydration, keeping them on aspirin, careful interoperative management of blood pressure and heart rate are all important. And then perioperatively, keeping them hydrated on aspirin with long-term followup, I think is a really important thing. So, you know, that's relevant to any level of neurosurgeon from the first-year intern to, you know, even guys like Dr. Scott who's been doing this for a very long time, and all the other colleagues that treat Moyamoya around the country. I think these are key points. So those are the kinds of things that I would hope would emphasize for take home management and questions about Moyamoya. I don't know what you think, Cormac. if you have questions for me about anything, but I think those are some of the key take home messages I try to emphasize here with this discussion about pediatric Moyamoya.

- Ed, thanks. I think you've hit all of the important high points on Moyamoya disease, and hopefully, that will serve as a wonderful refresher for all of the neurosurgeons out there and a good introduction to Moyamoya for some of the residents that might be watching. So once again, on half of a WNS Grand Rounds, and I want to thank you very much for joining us today for what I think was a wonderful session.

- Well, thank you, Cormac. It was my pleasure. I think this is a great forum to really disseminate knowledge and I appreciate your hosting. Thank you very much.

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