So I guess we'll go ahead and get the second half started. I'm going to talk about what I would say is maybe one of the biggest controversies that we deal with in brain tumor surgery, and that's what to do with the vestibular schwannoma. I think I'm going to talk about that. There we go. I don't have any financial disclosures, and I'll very much try and stay on time. And of course, how I thought about this presentation is there's a wide variety of people in this room. So there are neurosurgeons who are very experienced in the treatment of vestibular schwannomas, neurosurgeons who occasionally treat vestibular schwannomas, neurosurgeons that see a lot of vestibular schwannomas and then refer them on, and of course, people who are quite interested in expanding their practice in terms of vestibular schwannomas. And this has just been my experience. I finished my training in 1996 and then did a fellowship with Dr. Tu at the University of Cincinnati, and I spent a couple years at Mayo Clinic Jacksonville before I came back to Rochester in 1999. I call those my happy years, that three-year gap when I was not in Rochester, Minnesota. So I've now operated more than 700. I personally have treated almost 700 with gamma knife radiosurgery. I have a colleague, Bruce Pollack, who also does gamma knife radiosurgery. Now I have a colleague, Jamie Van Gumpel, who also does microsurgery for vestibular schwannomas. And I would say at any one time, I am actively observing more than 250 patients with vestibular schwannomas, patients who think of me as their doctor and come back and get follow-up. And we see now about 200 brand new vestibular schwannoma patients a year in Rochester. And of course, this is the question. What do you do with this patient, a 31-year-old? She's a mother of three. During her most recent pregnancy, she noted some right-sided hearing loss. They said, oh, it's probably eustachian tube dysfunction. She delivered. Everything went fine. And then she said, you know, I still have this oral fullness. And I got an audiogram. And she definitely has asymmetric hearing loss, with the right ear being worse than the left. But excellent word recognition score. And wisely, her doctor said, well, we better get an MRI scan to rule out retrocochlear pathology. And sure enough, she's got that. She's got about a 1.8-centimeter vestibular schwannoma. And so what should she do at age 31, a new mother with two other kids at home? Should she have surgery to have it removed? Should she have single-fraction radiosurgery? Should she have fractionated radiotherapy? Or should she just observe it? And I'll talk about that for the next 15 or 20 minutes or so. And so maybe we can come to a conclusion. And of course, this is what we think about usually when we see a patient with a vestibular schwannoma, that they have three options, provided they don't have a really large tumor or some kind of symptom that needs to be palliated, is they could have radiation surgery or observation. And it turns out there's been a lot of behavioral science looking at the science of decision-making. How do human beings make decisions, important decisions? And it turns out we do fairly well when presented with two choices. So there's lots of social science experiments that if you give patients two choices, one of which is usually the obvious right choice, 99% of people will take that obvious right choice. But an interesting thing happens when you add a third choice, is all of a sudden the number drops dramatically of what you would logically think would be the correct choice. So we're already complicating things by throwing in a third option. But this is what really patients are thinking about, at least in my practice, is they say, OK, should I have radiation? Well, should I have gamma knife or cyber knife or some type of other modality or protons is really a hot topic now. And then what type of fractionation scheme? And if they're going to have surgery, should they have the retrosigmoid approach and they're worried about headache? Or should they have trans-lab with no choice of saving their hearing? Or could they be a candidate for middle fossin? Do you want to retract up on somebody's dominant temporal lobe if they work as a neurosurgeon in a major academic center and so on and so forth? And then should they ask to, well, don't take all the tumor out, do a near total or subtotal because I really don't want facial weakness. And then, of course, if they have observation, where are they going to have it, at what interval? So it turns out that it ends up to be a lot more than three choices. And our brains don't work so well when we're faced with all these different things to think about. So it's usually a long visit with a brand new patient with a vestibular schwannoma to try and sort this out. And even if they decide one thing, there's no guarantee that if they have a subtotal resection, then are they going to have radiation afterwards or are they going to go on to observation? If they have observation, the tumor grows, are they going to have surgery or radiation and so on? So it gets even more convoluted as you go down the decision pathway. And so at least let's try and figure out what do we know about these tumors. And I think we should give a lot of credit to this very small country in northern Europe, Denmark. So it turns out in the 1970s, the Danes decided that every patient with a newly diagnosed vestibular schwannoma would be seen by one center in Copenhagen, and they would follow all tumors less than two centimeters to kind of see what happens. And in a small country that has socialized medicine, you can actually do that. It turns out that Denmark and Minnesota, where I live, are almost identical in terms of the same population. There's one big metropolitan center. It's Copenhagen in Denmark. It's Minneapolis-St. Paul, Twin Cities in Minnesota. But I can promise you we could never get even that arrangement in one state in Minnesota. But it was unique. And what they found, interestingly, in following patients is a minority grew. So in almost four years of follow-up, only about 30% of tumors grew. Most of the tumors just sat there and didn't change. There's a little bit of an issue because this was before the days of MRI, so they only had CT with contrast, so they broke it down into intracanalicular and extracanalicular tumors. There's a little bit of a problem with that. But other people have looked at this the same way. So the Gruppo Otologico in Italy, Mario Sanna's group, they looked at more than 500 patients, mean follow-up three years, and a little bit less than half grew by five-year follow-up with actuarial tables. Vanderbilt recently published their study looking at a lot of patients, and they had a follow-up of about two years, and about 40% grew. And then the Danes looked at just intracanalicular tumors, just small intracanalicular tumors. And with really long, almost 10 years of follow-up, only a third grew. So most small intracanalicular tumors don't grow in follow-up. And we said, you know, jeez, we've been following a lot of tumors in Rochester, Minnesota. Why don't we look at it and see if we get the same thing? So we had 232 intracanalicular tumors, 129 extracanalicular tumors, and our median radiographic follow-up was 4.1 years. And we looked at tumor growth in two different ways. One was volumetric, and we said the tumor had to increase by 20% volume to be considered growth. And the other is just the standard linear measurement. And why did we do that? It's because oftentimes these tumors aren't nice spheres, or they don't look like the typical ice cream cone laying on its side, but they're kind of multilobulated, and deciding, you know, what's growth here? If you're using linear measurements, you could get faked out. So what we did, if you ever wonder what the hell do we do in Minnesota over a long, cold, dark winter, is we digitized a lot of images and do volumes. And interestingly, what we found, and this surprised us quite a lot, is that almost 70% of tumors showed volumetric growth, more than a 20% increase a little over a year in follow-up, which was quite a bit higher than what some of the other studies showed. And if you just use the standard linear measurement, it was about half of patients showed growth a little less than two years follow-up. And one of the risk factors for growth, interestingly, is patients who present symptomatically with disequilibrium. Of course, facial hypesthesias and larger tumor size go together. But patients who show up with symptomatic tumors more likely have growing tumors is what we think this means. And if you just look at the Kaplan-Meier freedom from growth, you can see it drops off pretty dramatically. And of course, it keeps getting worse the longer you follow them, the more you find that are growing. And then interestingly, we always wonder, well, once it grows and they go on to treatment, what kind of treatment do they have? Well, the majority have radiosurgery. About twice as many elect have radiosurgery as microsurgery. And I think that's because they've already learned to live with their tumor. They're not the patients that say, I have to have my tumor taken out. And if you just look at the whole literature, if a tumor is going to grow, how fast is it going to grow? Well, it turns out in 2005, there were two, I'll say, meta-analyses that came out, one in the neurosurgical literature, one in the ENT literature. And they came out with very similar results that if a tumor is going to grow, it's going to grow about a millimeter and a half in a year. So patients will often say to us, I don't know if I want to follow my tumor. What if it grows rapidly, and then I wouldn't be a candidate for gamma knife, or the surgery would be a lot more risky if I'm going to have surgery. Well, it turns out if it grows, it's not going to grow very much. So it's probably a safe strategy. The next big question is, while you're sitting around doing nothing, just watching a tumor, what's going to happen with the hearing? Is the patient going to suffer some new deficit because you're not treating their tumor? And it turns out that, in a way, the answer is yes. Doing nothing puts the hearing at risk. And again, this is from the Danish cohort of almost 1,000 patients. So if you take the patients who start out with really good hearing, greater than 70% word recognition, less than 30 decibel, pure tone average, still about half of patients have that type of good hearing 10 years later. But that also means about half the patients have had a decline in their hearing to a significant degree. And if any one of us had perfect hearing in one ear, and less than 70% hearing in the other ear, you would notice that as unilateral hearing loss. You'd have trouble hearing in noise. You'd have trouble localizing sound, quite likely. And what's really interesting is any amount of hearing loss to start out dramatically impacts what's going to happen to the hearing. So these are patients who started out with 100% word recognition, because that's what hearing is to human beings, right? It's your ability to decipher the words that I'm saying at a very fast pace, because I can't help myself. That's the way I talk, even though I'm from Minnesota. So that's what's important for hearing. If you start out at 100%, you have a 70% chance of still having very good hearing, greater than 70% word recognition by 10 years. But if you have even 99% word recognition, the hearing drops off much quicker. And if you start out more towards down the 70% range, it really drops off and then kind of levels out. And this is just, again, looking at only intracanalicular tumors, because these are the tumors that are most likely followed, right? So somebody's dizzy and they get an MRI, or their teeth itch and they get an MRI, or their dog's getting an MRI, so they want an MRI. And then you find a little intracanalicular tumor, and you've got to decide what to do with it. So this is, again, only intracanalicular tumors followed a very long time. And this is the non-tumor year, at the time of diagnosis. And so you can see, over 10 years, there is some decline, presbycusis, people lose hearing with age, that the hearing drops off. So this is at the time of diagnosis, and this is at last follow-up in the non-tumor year. And you can see, the older you get, the bigger this gap gets. But this is the tumor year. So it starts off worse, okay? So this is at diagnosis non-tumor year, at diagnosis tumor year. And you can see, at last follow-up, there's a big gap. Or another way to look at it is that the word recognition score was, on average, 61% in the group, in the tumor year, and it went down to 34%. And we think 50% is kind of the magical cutoff. If you're getting less than half the words in a sentence, you're probably not understanding the meaning of a sentence, although people debate that as well. Or another way to look at it is, you know, to start out with, almost half the patients had very useful hearing, and 10 years later, only about 16% had very useful hearing. So even though the tumor didn't grow, intracanalicular tumor, there is some risk. And again, this just shows, if you start out with 100% word recognition, you have a heck of a lot greater chance of still having hearing 10 years later than if you have even a slight decline in the hearing to start with. So that can help us counsel patients. If they come in in this group where they have a 90% word recognition to start, you can say, well, if you want to observe your tumor, you've probably only got about a 30% chance you're still going to have useful hearing in that year, 10 years later. So I think, you know, we can conclude, yes, there is some risk to the hearing, and it really depends on where you start. Where you start determines where you end up. And if a patient comes in with 100% word recognition, probably doing nothing is a very, very low risk option. One of the things we wondered about is, could you predict, on that 10-year curve, what's going to happen to people? And so we thought, well, if we could figure out, is there an initial change in the hearing, when do we pull the trigger to do something? Because we know it's going to fall off a cliff. And I will tell you that there's a lot of evidence that shows that patient age, sex, the tumor size even, whether or not the porous has widened, is the tumor more towards the cochlear, or is there a good fundal cap? None of that helps predict hearing, it turns out. So we partnered with our colleagues at Vanderbilt, and we looked at patients who we've been following that had at least three serial audiograms and two MRI scans. And we calculated the rate of change, either as their pure tone average or their word recognition score at last follow-up, minus their pure tone average or word recognition score at diagnosis, and divided it by the number of months we followed them, and we said, that's the change. And what we found of 266 patients is this was the degree of maintaining hearing. So by 10 years, there was only a 44% chance that they would still have useful hearing. And for every decibel of pure tone increase they got per month, when you calculate it out, it's a 96% chance of falling off into the non-serviceable hearing. Or another way to look at it, this is hazard ratio for non-serviceable hearing. And if you go, for instance, so this would be basically losing 12 decibels in a year, one decibel per month, it almost doubles your chance of having not useful hearing. And if somebody really has rapid hearing loss, where they lose 30 decibels in a year, they have a very low chance of still having hearing. So once you start to see the hearing drop off, maybe there's an indication to do something. So that's what I think we know about observation. Radiosurgery, very popular treatment, of course, for vestibular schwannomas, and at least as of 2017, more than 100,000 patients have been treated worldwide with just GammaKnife. So that doesn't include CyberKnife or any of the other linear accelerator platforms. Most of the time, people are prescribed 12 to 14 gray to the tumor margin, and most reports suggest 93 to 98% tumor control, meaning the tumor did not significantly grow. Risk of facial weakness, very low, less than 1%. And risk of trigeminal dysfunction is less than 5%. And most papers report hearing preservation, 50 to 70% chance with GammaKnife radiosurgery. And this just shows the number of patients treated just with GammaKnife, and you can see it crossed over 100,000 patients a couple of years ago. And this is what the average dose plan looks like. The yellow line would be 12 gray. The green line is 4 gray. That's the cochlea. This is a fused CT and MRI, so you can see the cochlea well, and some people think cochlea dose is quite important. But if the tumor goes all the way out to the fundus, the cochlea is probably going to get more than 4 gray. And this is just kind of a summary we did for a review article in otolaryngology clinics a few years ago. But basically it shows from a lot of big centers that do a lot of this, you know, the failure rate is less than 10% depending on how you define failure, and that's one of the problems in the radiosurgical literature. Some people say it's only a failure if the patient goes on to get a second treatment, but, you know, that's probably a little bit disingenuous because it depends on when you audit the data, because you might have patients that just haven't operated yet, but clearly it's failed. We usually say if there's growth on two consecutive scans that that's failure. And then these are the hearing outcomes. Like I said, somewhere 50 to 70% is what's reported. But there's a couple things. The main thing is that the follow-up in all these very good studies is not very long, right? It's a mean follow-up of somewhere four to five years, and for the average 31-year-old patient with a vestibular schwannoma, that's not even a tick of the clock. They have to think about their hearing over the next 50 years statistically in the United States. And most of this is from retrospective data. There have been a couple prospective studies, one we did and one that was done in Bergen. So we got particularly interested in, but what's the long-term? If you're going to talk to a 31 or even a 51-year-old or a 61-year-old patient, they want to know for the next 20 years. So what we did is we looked at the patients that we had treated between 1997 and 2002 using contemporary techniques, and we sent them a check. And we said, please get an audiogram and send it to us. Here's $50. And it worked pretty good. We got 77% follow-up. And this is what it showed. So with a median follow-up of almost 10 years, it showed that about half the patients still had hearing by three years, but by 10 years, it was only 23%. And this is just, again, the Kaplan-Meier curve. You can see it kind of drops off in the first few years, but then there is a steady kind of decline in the hearing, and all these patients had tumor control. It was a successful treatment. Their tumor was not growing. And what predicts getting to keep your hearing if you have radiosurgery? Well, it's starting out with good hearing again, just like with observation. Patients who had Class A hearing did much better than patients with Class B. And having a smaller tumor, less than one centimeter versus greater than a centimeter, made a big difference. And that probably has something to do with the amount of radiation to the cochlea, to the cochlear nerve, to the cochlear nucleus, and so on. And it's not magical. With Gamma Knife, this is just from a paper from a ruse from Australia using a linear accelerator. And just by chance, they got exactly the same number, 23% chance of keeping hearing by 10 years with linear accelerator radiosurgery. There was a recent meta-analysis just published last year that looked through all of this, more than 2,000 patients, and this is what it showed. So once again, yeah, 70% at 2 years, but once you get down to 10 years, that same number keeps coming up, 23%. And this is just the plots. The size of the bubble has to do with the number of patients in the study, and this is the actual follow-up. And you can see there's this fairly constant regression line that shows hearing continues to drop off the longer you follow patients. People have wondered, does fractionation help? Should instead of doing a single fraction like with Gamma Knife, should you give 3 or 5 or even 25 or 30 fractions? And the punch line of this horrible slide is it doesn't seem to matter. It doesn't really seem to improve hearing outcomes. This is, again, another meta-analysis from last year looking at hypofractionated treatments, so 3 to 5 fractions, and you can see that also only 37% hearing preservation, so very similar. This is one thing that we found and published a couple years ago, which was very interesting to us, is we looked at—let me put it this way. One of the big criticisms of radiosurgery is maybe we're treating a lot of non-growing tumors and taking credit for it, right? Because I showed you from our data and from the Danish data, a lot of tumors will just sit there. And so you give them 12 Cray irradiation, and maybe the patient's acne gets a little bit better, and then you can say, okay, I've done a good thing. So we looked at our series of patients. We knew only the tumor was growing, and we calculated the growth rate before and after radiosurgery, and surprisingly, tumors that were growing fast, more than 2.5 millimeters a year, we got only 70% tumor control. Tumors growing less than that, 97% tumor control. There have been a couple papers that have come out since that that dispute that, but this has changed our way we counsel patients. If we see a fast-growing tumor, I am much less likely to recommend radiosurgery, or at least I tell the patient, I think there might only be a 70% chance we're actually going to get control of your tumor. I just want to say a few words about surgery, of course, before we conclude. You know, there's three different approaches for small intracanalicular tumors, or even some people operate small tumors in the CP angle. I'll say we don't do that, but you can operate from above. One of the problems is the facial nerve is draped over the top of the tumor, but you can dissect that off and take the tumor out. Translabyrinthine approach changes the angle a little bit from the retrosigmoid approach. You can operate any size tumor with either of those two approaches. And so what results can you expect from surgery? Well, like with anything else, you've got to track your own results, but this is a paper that the Samis put out now over a decade ago, but probably nobody will come close to accruing the experience that Majid Sami has accrued with vestibular schwannomas. Last he said, I think he's operated 3,500. So I calculate that out. I'm going to have to live to be about 184 to operate that many at this rate. And so this is just 200 in sort of his modern series. He did a gross total resection in 88%, which means in four tumors, they left a little bit. He had one recurrence after what was thought to be a gross total resection. Preserved the facial nerve anatomically almost 100% of the time, but 80% of patients had Hauss-Brackmann grade 1 to 3, and it's very controversial if you should throw in the Hauss-Brackmann 3 designation as a good facial nerve, but that's what the data showed. They preserved hearing in 50%, but again, that's a very liberal definition of hearing, so most people don't count that. They had a couple percent CSF leak and a very low rate of serious complications, 1% infection, two small intracranial hemorrhages, neither of which had to go back to the operating room, and no patients died. Those were all done retrosigmoid in Hanover, Germany. This is again from Denmark doing 1,200 translabyrinthine operations, and lo and behold, the results are the same. No surprise. It's not the approach. That's the difference. They looked at Hauss-Brackmann grade 1 to 2, so they threw Hauss-Brackmann grade 3 out, which is what I would recommend. That's what we do with our data, and it was 70% good facial nerve. Interestingly, my CSF leak rate is a little over 9%. That's not an insignificant problem, and I always counsel patients about that. So if we step back and say, okay, so those are three options, and that's kind of what the data shows, and this is what you can tell patients. If you have this treatment, this is likely what's going to happen. What's actually happening? What are we doing in the United States? One way to get to that are these big databases, right? So the SEER database looks at 20 population-based tumor registries scattered throughout the continental United States, and it encompasses about 28% of the U.S. population. And now, so you can look at data on over 8,000 vestibular schwannoma patients. It gives you about 790 million person-years of data, and you can get some just general demographics. So the mean age at diagnosis is about 55 years. A little more than half of patients are women. Just like every tumor registry that's ever been published, minorities are underrepresented. There's probably a lot of reasons for that, but the same with this database. The incidence is only about 1-2 per 100,000 per year, and there's been a definite increase in the number of elderly people being diagnosed with this tumor, and there's been an increase in the number of smaller tumors diagnosed. And again, it's just because MRIs are on every corner, and everybody's getting an MRI for everything. And what it showed, when you look at 2004 to 2011, so almost a decade's worth of data, it turns out about half of tumors in the U.S. get operated, about a quarter get treated with radiation, and a little over a quarter get followed. And if you look at trends, again, 2004 to 2011, so the kind of greenish bars are the number that were treated with microsurgery. You see it's going down. The number being observed is going up, and the use of radiosurgery or radiotherapy has been about the same over that period of time. And I think it's really important to look at, when we think about surgery, we often say, well, do you want to be cured? Do you want you and your tumor to have different addresses? Then surgery will accomplish that. But it turns out, you know, when you look at a big database, you know, about 20% of people end up with a subtotal resection where they leave tumor behind, so it's not a cure. And who gets a subtotal resection, no surprise. So people with big tumors, you know, if you have a tumor over 4 centimeters in the U.S., there's close to a 30 to 35% chance that you'll have some tumor left behind at the end of the operation. Small tumor, even less than 2 centimeters, there's still a 10% risk that some tumor will be left behind. One of the things that we've been keenly interested in over the last many years is the disconnect that I often see in my practice, where I do an operation or gamma knife, or I'm observing the patient, and I think things are going great. They still have hearing, their facial nerve is normal, their wound healed up well, their tumor's shrinking after radiation, and the patient says, I'm miserable. They say they're very unhappy. And so what we did is we partnered up with our colleagues in Bergen, Norway, and we sent a 273-question questionnaire to all the patients we'd either observed, radiated, or operated over a 10-year period, including the Panacoustic Neuroma Quality of Life questionnaire, which has disease-specific questions, and we basically asked them, how are you doing, seeing if we could figure out who was doing better. Would it be better to have radiosurgery, microsurgery, or observation? And surprisingly, there's not much difference in those three groups of patients, and that's at a mean of almost eight years after treatment. And it turns out, when you compare non-tumor controls, so we surveyed 103 people in the U.S. that don't have acoustic neuromas and said, would you please fill out the survey, they had a much better quality of life than any patient who has a vestibular schwannoma. And we found out things like the SF36 and those are terrible for figuring out who has a tumor, so you really have to use the PANQOL. And the other thing we found is that when you get a large number of patients, this is just a statistical sort of nonsense thing, is you can get a lot of P values, but they're not clinically significant. When you look at the minimum clinically important difference, which you can calculate, like for instance for the PANQOL, it's 11 points. And this is what our results were. So the total PANQOL score for the radiosurgery patients was 70, the observation patients a little better at 72, and the microsurgery patients worse at 65. And all of these differences are highly statistically significant because we had so many patients in our study. But when you actually calculate on a 100-point scale of the PANQOL total score, you need an 11-point difference for a patient to actually be able to know there's a difference. And all these fall within 11 points, so it's probably not clinically significant, although statistically significant. It turns out a group in the U.K. did the exact same thing we did and published it last year, and they reached the exact same conclusions. Not a big difference in overall quality of life, depending on treatment modality, which frankly surprised me. So it gets back to the original question. What do you counsel for a 31-year-old woman with a 1.8 centimeter tumor and still good hearing? And I think it's still a big question, and it takes a lot of counseling and patience, I think. I think what our data on quality of life shows is that patients reach the right conclusion for them. So they become invested in that decision, and when you survey them many years later, they say, yeah, I did the right thing. I'm happy. It's kind of like if you ask me, do I like the house I live in? Well, I paid a lot of money for it. I guess I do. It's that kind of thing. So what I would say is that, first of all, doing nothing, just following patients, wait and scan is a very low-risk option, and a minority of patients certainly won't have growth over five years. Hearing may continue to decline even if the tumor doesn't grow, and where the hearing starts usually determines where it ends up. And of course, the big thing about wait and scan is the patients cannot fall out of follow-up. They have to be reliable and come back and get follow-up, or they may show up years later with a very difficult problem. I think we can say at least 90 percent of patients get tumor control with radiosurgery. Faster-growing tumors may not respond as well. I doubt if it matters CyberKnife or GammaKnife or any of these other things. I think that's a Coke versus Pepsi argument. I usually tell patients if you have radiosurgery, you're going to have a 50-50 chance of still having hearing by five years, and an only 25 percent chance of having hearing by 10 years. I didn't show any of the data just in interest of time, but the risk of malignant transformation and those kinds of things is extraordinarily low. The risk of facial weakness with GammaKnife is less than one percent, and I also didn't show the data of this, but I think surgery after failed radiation is a bit more difficult. It's hard to quantify that, but I think it's true. Surgery, of course, separates the patient from the disease, but gross total resection, at least in the U.S., is done only about 80 to 85 percent of the time. Somewhere between probably 75 and 85 percent of patients will end up with good facial nerve function. Hearing preservation is much more nuanced. It depends on, again, where the hearing is going into the operation. Is there a fundal cap of CSF? Is the tumor firm versus soft? Those kinds of things. And, of course, you have to counsel patients about the real risk of CSF leak or infection or so on, as with any operation. Every four years, it turns out, there's an international meeting about vestibular schwannomas. Four years ago, it was in Shanghai, China. It's been in Copenhagen, in Paris, in Cambridge, England, in Los Angeles, and naturally, the next logical place to have it would be Rochester, Minnesota. So it's going to be in June, and if you're interested, there's the website. We'd love to see you in Rochester. I promise there won't be snow on the ground. I'll stop there. So what happened at that meeting? We took her tumor out. She ended up choosing to have surgery after we talked to her about all this stuff, and so we took her tumor out and lost her hearing. She lost her hearing. Yep, she lost her hearing. Her facial nerve was okay. We think we did a gross total resection, so we'll follow her and... So to the patient, our center in Toronto, we have a center that will not operate unless the patient's large, massive, and that's a different thing. We've got a tumor that's less than two percent, it's already two percent, will not operate unless we document growth. I've got just that argument. The issue is really, you know, 30 percent did not do it. You're taking credit for the other 30 percent, so what's the downside of waiting for you to document growth? And we follow very carefully. Yeah, yeah. You know, I think there's two risks, basically, of wait and scan. One is that the hearing could drop off and you'd say, oh gosh, we should have done something in April of 2019, and maybe we could have saved your hearing. I always say to patients, if that happens to you, if you walk out of this office and next month you're deaf in that ear, I would have made you deaf in the OR. It means that your hearing is on a very sharp precipice. And then the other risk is that they'll fall out of follow-up. But I will tell you that the number one treatment for a vestibular schwannoma at the Mayo Clinic is nothing. So we observe most tumors that we see as the new. And just like in Toronto, I'll say in Bergen, Norway also, unfortunately, I do think we have a little bit of a Burger King mentality in the United States, where if a patient comes in and says, I want my tumor out, you know, honestly, I don't argue with them very much. I make sure they understand. They have this option of radiation. They have this option of observation. But sometimes people have very compelling reasons. And we say, OK, we'll take your tumor out. I'm happy to say it's a very rare event in our experience. So yeah, I agree. And I've had a patient the very next day, the very next day, go completely deaf in the ear. And because it's so rare, I don't have any way to study it to know. We give the patients steroids. Sometimes we do transtimpanic steroids. You know, if they're still in our area, we'll bring them in the office and try and get their hearing back. But I don't know why it happens. Yes. Yeah, I think it's a great question. And it's a very hard thing to study. I think for some of the patients where we say, your tumor isn't growing and the patient's hearing is getting worse, I suspect the tumor is growing. But it's confined within the internal auditory canal. So the volume can increase, but the pressure can't. And so that is bad for the nerve. I think there's a small possibility it has something to do with the vascular supply to the inner ear. But there's no question having a tumor on the eighth nerve ages that nerve. It deteriorates faster. I think the more intriguing question is after you radiate a tumor, why do patients lose hearing? Because we see some dramatic radiographic responses where the tumor really shrinks. And I think people concentrate on the cochlea dose because that's the only damn thing we can measure. You can't measure what's the dose to the cochlear nerve because you can't really see the cochlear nerve or the cochlear nucleus. Or maybe it's the stria vascularis of the cochlea that's the important part. Maybe there's a critical radiation dose. Well, we can't measure any of that. But again, it's probably is it tumor swelling after radiation? That puts pressure on the nerve and the nerve kind of gives up. Or do you lose the microvasculature coming along the nerve when you radiate and that results in kind of an infarction in the cochlea? There's no way to know, but I think it's one of those mechanisms. Ian. Question. Do you expect to see an increase in the size of the tumor after you radiate through the root vessels at some point? And how much do you think is excreted into that? Yeah. No question about it. Most tumors look bigger at the six-month follow-up. So our typical strategy used to be to do gamma knife and then six months get an MRI and a hearing test. And then at one year, MRI and hearing test. And then yearly for two more years. And then every other year for four years. Then every three years for six years and so on. And about 70% of tumors were volumetrically bigger at six months. Many had also lost their central enhancement. And then a small minority of those will be back to the original tumor size by one year. And then rarely you see ongoing decrease in the tumor. Once you get past 18 months, if you still see the tumor get larger, I think it's very likely failing. I think it's very likely failing. But we see a substantial number of tumors that we radiate, they get bigger, and then they just stay bigger and never change. They don't get continue to get bigger and they don't get small. And I think that's okay. Just a comment about that. So this issue of progression, it's very common. Yeah, it's a very difficult thing to decide is sort of when to declare failure, I think. Yeah. Yes. When a patient is therapeutically anti-coagulated, for example, for atrial fibrillation, is that a relative contraindication for radiation in the spheneal center? No, it's the opposite. It's an indication not to take them off their anti-coagulation and operate on them. It's keep them on their anti-coagulation, put the head frame on, they can be on any kind of anti-coagulation. I don't know. Radiation oncologists being quite reluctant to have a bad experience is spontaneous. They're ridging them off after surgery. Really? Yeah. That's like an enema. Wow. And now we say it's a relative contraindication, which is kind of opposite to what we're doing. Yeah. We haven't seen that. Interesting. It gets spontaneous. Yeah. Yes. For patients who seem to be under good control with whatever treatment you've done, do you have a cutoff if you don't follow them anymore on the scans? Yeah. That's a great question. And I've asked, you know, Dave Lunsford and Jean Regie and so on that very question. And people have said that if you have a documented tumor, some people say after five years. But I have to say, I follow the patients forever. Until the day I retire or die, I'm going to keep telling patients they need to at least at some point periodically come back and get a scan. I'm happy to say, you know, one of the rubs of radiosurgery also is people said, oh, it's going to work for a while. And then in five or eight or 10 or 15 years, you're going to see this avalanche of patients come back with growing malignant tumors or just growing tumors. It's not going to work long term. But we haven't seen that. It is rare as a hen's tooth to see late failure, meaning more than five years out. I will say to Ian's question that we've stopped now looking at tumors at six months, though. We have cut out the six-month follow-up. We say you have gamma knife, come back in a year. Because we never do anything at six months. So we're figuring we're saving the health care system. It plays a lot. So the fact that the patient I showed you was 31 years old really, I would say, swayed us to say, you're 31. If we do gamma knife, statistically in the United States, you have to think about the next 50 years, it's a two-centimeter tumor, let's just take it out. If that patient was even 61, I'll say, I would start to bend the curve the other direction. So age, comorbidities, they make a huge difference. If you skip that six-month scan, then if it grows up to one year, do you consider that a progression? Yes. Yeah.

vestibular schwannomas

brain tumor

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radiation therapy

observation

counseling

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