 Isn't that nice out there this morning? Isn't that lovely? We're like interviewing applicants for a fellowship. And it's like, well, if you pretend there are mountains on the other side that you can see. As a comedian in LA once said, I don't trust air I can't see. So you can definitely trust this air today. All right, so we ran out of pictures of Barcelona. So this summer I was in Scotland lecturing. And when they said, well, what do you want to do for a day? I said, ah, can we go to Edinburgh? So they were nice enough to drive me to Edinburgh. So this is Edinburgh Castle. And so like many medieval cities, you pick the highest hill in the city and you build a big fortress or castle. And so you can see they took this hill and they built Edinburgh Castle. And here's the trip up to it. You can't really tell, but in Scotland it's always gray. So it's just gray, kind of like here today. But it's just gray, always gray and a little bit drizzly. So you always bring a coat. But it's an impressive fortress. They took this big hill and they basically just carved this whole fortress out of it. And this is as you're going up to enter. So you can imagine trying to conquer that in medieval times. Although people did, basically this was conquered a couple times. What happened is the guys would sneak up in the middle of the night and they would put lob things over here and then climb up and get inside and then open the main gate and let the other guys in and take it. So this was conquered several times back and forth. And here you go when you get in. Here's the main gate. Now it's interesting in that they have taken the main courtyard that's in the middle of this and made it into a huge stadium. And so they put stands on both sides. And then they do this fireworks show and this big show in the summertime. Unfortunately, I couldn't stick around for that. But it's supposedly pretty impressive. So here's the main gate. Here's all the tourists you're lining up to get in. Of course, just like anywhere else in the world, about 50% of the tourists are now from China. And so most of the world's tourists are now Chinese. And so there's a lot of Chinese tourists in Edinburgh. All right, so today we're going to talk about the optic nerve. And so this is what we should be seeing in a nice, normal optic nerve. We should see a good color, no pallor. We should see sharp edges, no elevation, no hemorrhages, no dilated blood vessels. It's so a nice, normal optic nerve. All right, Nick, since you're sitting there, what stain is this? Why am I using this thing? Trichroma, why would I use trichroma? So it stains the connective tissue blue. So it would be the sclera, the optic nerve sheath, even the pia mater here. And of course, it's got the perincoma, the nerve itself, red. And so this shows nicely the structure of the optic nerves. Remember last week we talked about when an axon leaves a ganglion cell, it goes through the lamina crebrosa right here and then Julia, what happens to an axon after it goes through the lamina crebrosa? What happens on the posterior side to that axon? It's not myelinated to that point. It gets myelinated, exactly. So once the optic nerve fiber, the axon, comes through the lamina crebrosa, it becomes myelinated. And so you've got a lot of oligodendrocytes in here that myelinated and that's what happens when you look at the optic nerve head. It's about maybe 500 microns in diameter, but the optic nerve, once it goes through the lamina crebrosa is about 1500. So it gets much bigger partly because of the myelination but partly because of the optic nerve sheath that's around it. And so when you look at the lamina crebrosa, it's interesting when you look at scanning EM views, it's really like a porous network. The fibers have a kind of sinuous path that goes through there. They don't just go straight through and this is nature's way of adding strength but still allowing fibers to come out. So if you think about it, if there was just a hole back there and the optic nerve was plugged in, as soon as you got hit in the eye, that optic nerve would just pop off. So this gives it some strength because you've got these little fibers that are going through here, these collagen fibers that the axons go through. All right, so I guess reach your next. We've got the optic nerve in cross section. Tell me a little bit about the tissues around the optic nerve and surrounding the optic nerve. You'll sheath around this. Dura, right? Right. So what do we call the dura that's right here? Optic nerve sheath, exactly. And then underline that. Right here? Okay, and what flows through the arachnid there? CSF. CSF, good. And then the inner layer? Pia. Pia. So if you think about an optic nerve, think about the analogy of the fiber optic cable. An individual axon is that single little fiber optic and it is surrounded by myelin. And then the axons are bundled into these bundles and they're these little pioceptae that go all around it. So that's like when you've got the bundles of the various optic nerve fibers. And then lastly, it's put into this steel pipe and buried in the ground. So that's the optic nerve sheath that's around it. So it's like a fiber optic cable. Now, what are these structures right here, Brian? I think they're not real ones, it's a simple retina. There's no artery in the foc. It's a simple retina. Okay. We talked about the importance of the fact that they share a common adventitial sheath as they come in. Therefore, the most common cause of a central retinal artery occlusion is arteriosclerosis. Most common cause of a central vein occlusion is arteriosclerosis right there. All right, so we look at a close-up back to that trichrome. We've got here our dura, the optic nerve sheath. Here's the arachnoid subarachnoid space where the CSF fluid is. And then here's your Pia motor, but you can see there's little Pial septae that go through here and they surround these bundles of these little axons that are going through. Good evening. Good evening. All right, so there you go, the axons. Okay. This just shows it longitudinally. Oh, you've got perfect timing here, Ashley, since we are looking at optic nerve today longitudinally, these are the axons of the ganglion cells here. What cell bodies are these that are in-between these little columns of axons? Okay, so astrocytes. There are some astrocytes in there. What other kind of cells? Alligodendrocytes, good. And lastly, there may be a few little microglial cells, just like anywhere else in the brain or in the CNS. And here this just shows you what we had talked about, central retinal artery, central retinal vein. And so they will eventually come together and then right at the optic nerve head they are right together to share that sheath and then they eventually branch off when they come in there. All right, Russ, what are we looking at here? Demonstrate sort of optic nerve hyperinflation. It's literal crescent. So at first glance, you say, maybe this is just a normal optic nerve, a little myopic crescent, but when you look real carefully, look, there's the optic nerve right there. So this is actually a small nerve, a hypoplastic nerve. And then of course around it you've got this little crescent of scleros showing through. Would that be unilateral or bilateral? Okay, and what's the patient's vision? In fact, usually normal. And so the interesting thing about optic nerve hypoplasia is it's a finding you look at it and you see it, but really the patient's vision will be normal and they may often not even know they've got this or nobody's mentioned it to them. Now, if you looked at their children, would they have it? Yeah, so this is usually how does someone dominant. So it's one of those things that looks interesting but really doesn't cause a whole lot. There's some question whether smaller hypoplastic nerves or more at risk of AION, but it's really not panned out to be true. I think it's, if you worry about AION, it's more the fact that there's no cup in a really crowded disc rather than the fact that it's a hypoplastic disc. So hypoplastic discs look interesting but they really don't do a whole lot. This is a little bit different here, Niko. What do we see in here? Almost, but not quite. So what do we call it when it's not quite become a morning glory? It's actually an optic nerve coloboma. And I mean, morning glory fits in a coloboma. That's just a severe optic nerve coloboma. So this is an optic nerve coloboma from what language? From the Greek, of course. So optic nerve coloboma. So what you see here is this is usually found inferiorly in the optic nerve. And this is thought to represent an area where when you remember we looked at the embryology in the very first lecture, how the optic vesicle will invaginate and then the vessels will grow in and then it'll seal off at the equator and then eventually go anterior and posteriorly. So this is a failure of fusion posteriorly of that original optic fissure. And so you see right here, you're just looking at bare square there. Look at those vessels dive down. So this is going away from you. You see just what's left of optic nerve there. And this is totally atrophic here. So they'd have a big optic visual field defect in this area. And sometimes with these colobomas, you can even get leakage of fluid coming out here into the area of the macula. So that's an optic nerve. Let's see if you can highlight again where the coloboma is. Right there. And if you look at 3D, look at that vessel diving and that's going away from you. And so this area right here, it's totally maldeveloped optic nerve. And then the only normal optic nerve is up here. So this whole inferior two thirds is completely non-developed. And then this is the so-called morning glory. And so for added bonus points, what is a morning glory? It's a flower. So this is called morning glory. If you think about it, it looks like a trumpet horn. So this is what a morning glory flower looks like. You're looking down into the middle of it. And when we go back here, this literally looks like you're looking into a trumpet horn. So this is a severe optic nerve maldevelopment. And so it's like you're looking down into a trumpet horn. If you look, here's some vessels here that you can see in focus. And this is all blurry. And the reason is, that's going away from you like a trumpet horn. So this is a severe optic nerve coloboma. It's called the morning glory syndrome. Fortunately, these are usually unilateral. They're not bilateral. And so oftentimes these kids will have a normal other eye. Here's the morning glory. Okay, Renee, what do we see in here? Exactly. So if you look right here, there's an optic nerve pit. And the reason I put this is blatantly obvious. I mean, even a resident can get this right. So really obvious. But maybe a fellow. I don't know if it's that obvious or not. Probably not, it's their student. But so they're usually not this obvious. Usually they're a lot more subtle than this. But this is an optic nerve pit. And it's interesting, it's thought again to be a small developmental anomaly. And you see that little optic nerve pit right there. And when you look right here, you'll see that we've got this area right here where the pit forms. And now the optic nerve pit, you can get maybe a focal visual field defect, but what's the most common reason for a visual loss if you've got an optic nerve pit? Yeah, so you get fluid, percolates underneath the retina, because these are usually temporal. So percolate underneath the retina into the macula. And you'll end up getting a little macular detachment. These are really tough to treat because you can't laser right at the temporal head of the macula because you laser that to seal it off. You'll kill all the fibers coming out of the phobia. So these are very, very difficult to treat. And people have theorized that it's actually CSF leaking out underneath there. Other people have argued and said, nah, it's just leakage of fluid there. But when you get this pit, you'll get leakage of fluid underneath there. And you can get a focal, sub-macular fluid and serious detachment that can cause visual loss. What do we see in right here? Again, a blatant view that we have. So, Jack, can you tell me what the heck that is? Yeah, what's abnormal about it? Why is that all white? If you look, you can hardly even see the blood vessels. It's like that white stuff is just obscuring it all completely. This is actually severe myelinated nerve fiber layer. And so remember, normally we said that that myelin doesn't start till posterior to the laminocrobrosa, but sometimes when it's becoming myelinated, it will actually spill over anteriorly. And so these are myelinated nerve fiber layers. Now, the interesting thing about it is is the axons still work normally. And so you'll get what's called a big blind spot on the visual field, the heaven and large blind spot, because this myelin will block off the little rods and cones underneath there. But in terms of vision, your vision is otherwise pretty normal. So again, this is a curiosity. And you could find these focally. You know, when you first see them, people will say, is that a cotton wool spot or what? But usually they'll be located around the optic nerve because when the myelination starts, it's interesting, the myelination when the eye is being formed starts at the chiasm and comes forward. So the optic nerve grows from the eye back, but the myelination comes from the chiasm forward. And sometimes it will spill over through the laminocrobrosa and end up inside the eye. So these are myelinated nerve fiber layers. All right, Nick, what do we see in here? Yeah, so it's pretty small cup to discretion. In fact, it's almost obliterated. What do you make of the disc margins? Yeah, they're kind of hazy. You don't really see the disc margins real well. What's going on right here? Yeah, that's actually for real. I don't know how to work photoshop, so I mean, I can't do that. That's actually an optic nerve head drusen. And so, you know, drusen just means bumper deposit. So when you say drusen, we're usually thinking about the deposits under the macular and macular degeneration, which you can have deposits in the optic nerve head called optic nerve drusen. And when they're on the surface, you can see them pretty easily. The problem is, is when you have buried drusen, it will give you the appearance of papillodema. It'll look like a swollen nerve. And well, every once in a while, get patients referred in for an acute papillodema workup and you look and you'll see drusen. And they're often bilateral. So you can get this bilateral elevated nerves. You have to be really careful of what you call papillodema because this is not a swollen nerve. This is a nerve that looks swollen because of all the deposits there. And you can see just a couple of different views. And these are usually bilateral. So you can see again, this lumpy bumpy look to it. And it's easy to see when they're superficial. Again, when they're deep, it's more difficult. And this just shows you, this is actually an eye that has had actually damage from drusen. It's very uncommon, but in severe drusen, you can eventually get arcuate visual field defects and then eventually visual loss of a thank God that's very uncommon. Now this just kind of shows you how these buried drusen can look like papillodema. I mean, you're looking at this, you look at this, oh my God, this person's got increased intracranial pressure. Julia, what's a test you can do easily in the clinic to differentiate buried drusen from papillodema? Out of fluorescence is one, but if they're really buried, it sometimes doesn't show up. Ultrasound, which one? A or B? Yeah, but A or B? Oh, you thought you meant questions. A or B, fluorescence or ultrasound? No, A mode or a B scan, exactly. So, sorry. Yeah, just come to think about it, that's a logical answer to that question. Yeah, okay. So if you could take the B scan ultrasound, you could put it on the eye and you find your optic nerve shadow. And as you're turning the gain down, and you turn the gain down and down and down, you'll see these little areas where the drusen are lighting up. And why does that happen? Because they're calcified, exactly. So, when you look at these, now this is just an old CT scan, just to show you, this is from when I was like a resident. So, it is to say CT scans have gotten a little bit more precise now, but you see these little white things down here in the optic nerve head? You can actually see the reflection of the calcium from the drusen in a CT scan. And this is a better scan that you can see here. And again, you see those little calcified drusen bilaterally. So, this is a little bit of a better generation CT scan. And this just shows you grossly. This is a eye that's been cut in half, sagittally. And here's the optic nerve head coming back. And sure enough, there you see that white area underneath here. And when we do the pathology, we can see that calcium shows up as a magenta-colored amorphous material. And it's in front of the laminar kerbosa here, but you can see this particular drusen is buried. So, here's the optic nerve, central retinal, I'm sorry, artery and vein coming out. And you can see this calcified drusen that's buried deep. So, you wanna be really careful when you are seeing presumed papillodema. And you wanna make sure that it's really papillodema, it's really swollen optic nerves and it's not buried drusen. And so, you can do an ultrasound right in the clinic and that'll help you. This just shows you another view. Here's some calcified drusen here, down deep here, and then this one's a little bit more on the surface. So, optic nerve head drusen. All right, what do we see in here, Rhys? All right, so what do you think's going on here? Okay, so when I took oral boards, I got skewered by the reviewer when they showed me exactly. So, papillodema by definition is bilateral and it is edema secondary to increase intracranial pressure. So, I said, well, papillodema, oh man, he just pounced on it. He was jumping on me there. So, you wanna be careful when you just see one, you say a swollen elevated disc and then they say, well, what's your differential? Well, if it were bilateral and there were increased intracranial pressure, it could be papillodema. However, it could be just, you know, focal swelling from one particular site. So, be careful. Don't fall into that trap as I did. All right. And so, we're looking here. This one's a little bit more prominent. So, again, this would be something, maybe even Jack could make this dive, maybe, so I don't know, because he's the student, so maybe, but. So, you can see right here, not only is that elevated, the disc margins are obscured, look at the superficial hemorrhages that are there, but not only that, look how tortuous the vessels are, especially the veins. And so, when you get increased pressure like that, you can get back up a flow coming out and you can get tortuosity of the veins. So, this is severe, you know, grade four or five, depending on what scale you use optic nerve edema. And if this were bilateral, it would be papillodema. This just shows you what it looks like pathologically. Here's your laminar crebrosa down here, and look how elevated that optic nerve head is. And not only that, look at how dilated these little vessels are, but you've also got hemorrhages here on the surface of the optic nerve. So, you've got definite signs of papillodema, of swelling, there's secretarity increase intracranial pressure. And this shows you the forward bowing of the laminar crebrosa. So, you actually get the laminar crebrosa pushed forward from this increased pressure. And there you see the fibers of the laminar crebrosa bowing forward as if something's behind them, pushing them up. All right, what do we see in right here, Ashley? Yes, if you look right here though, if you look over here, there's not as much swelling there, and the swelling is more focal in this area here. So, what if you've got an area where you've got more of a focal swelling there instead of just a few salivation and swelling? What would get into your differential now? Okay, so N-I-O-N, what group does that fit into? What overall umbrella of diseases that can affect the optic nerve does N-I-O-N fit into? Ischemic, exactly. So, what you worry about when you see a nerve that's swollen more in one area than another, and you don't see a whole lot of hemorrhages on here, and it's more of focal swelling, and especially it's unilateral. One of the things you start to worry about now is maybe this isn't just swelling, secondary to increased pressure. Maybe this is swelling, secondary to ischemia. And so, in terms of the patient's symptoms, how would an ischemia affecting the optic nerve behave differently than papillodema or swollen nerve? Okay, sudden vision loss. What's the vision loss in someone with, say, papillodema that's not terribly severe? Yeah, exactly. So patients can have, you look in and their optic nerve looks horrible, and they can have pretty good vision. Maybe, again, a big blind spot, but pretty good vision. Whereas, you look at this and you see some focal areas affecting the nerve, yet they could have some profound visual loss. And so, this is where you start looking at ischemia as a cause, and what's another cause of some focal swelling of the optic nerve beside ischemia, another big main category. Young person, unilateral visual loss, pain on movement. Yeah, so demyelinating disease can sometimes look like this too, although often what's interesting about demyelinating disease is the swelling can be very subtle. You often don't see that. Yeah, actually, even in AIOI, it can be fairly subtle. So, when you start to see a unilateral problem with the optic nerve like that, some subtle focal swelling, you want to look at main categories of ischemia. You want to look at, could it be demyelination? And so, that's your differential diagnosis. And of course, things that will help you is how old is the patient? You know, if they're 20, you know, you're going to be looking at more of a demyelinating disease. If they're 70, you're going to look at more of a ischemic disease that can cause that. But just looking at the nerve is hard because they often all look the same. Now, this particular patient happened to be 70 and they had pretty good visual loss. What the heck is this? What is this doing in this lecture? Yeah, still actually just because I want to tell me what this is. Because you know this, Brian. So, very good. So, why the heck would I show you a temporal artery after showing you that? Exactly. So, when you look at anterior ischemic optic neuropathy, remember, there can be arteritic and non-arteritic and you definitely don't ever want to miss temporal arteritis, the arteritic form because the patient couldn't go blind not only in that eye, but in the other eye. And so, when you do a temporal artery biopsy, you look for that. Is this biopsy positive or negative? Pretty intact all the way around. Yeah, so this is a negative one. This is one I hope my temporal artery looks like this right now. I mean, if you look, minimal thickening of the intima, internal elastic lamina completely intact, muscular media intact, adventitian normal, no inflammatory cells on it. So, this is a negative temporal artery biopsy. And then, I often show you this at low power. So, now, Brian, what do you think about this one? First of all, what do you make of the lumen? The intima? It's thickened. Markedly thickened. And where is the internal elastic lamina? Yeah, it's pretty much chewed up. And in fact, do you see any normal muscle fibers here? What is that thing right there, probably? We'll go to Hyroponics. Yeah, that looks like a giant cell. And then you see these little blue dots around the outside. And so, this would be a positive temporal artery biopsy. And sure enough, some people would name this giant cell arthritis because you do indeed have giant cells. And they tend to be either along the inside of the muscular media where the internal elastic lamina is, or there on the outside. So, I don't know what it is. People have argued, is there something that attacks the muscular medias? Does it attack the internal elastic lamina as an autoimmune disease? I don't think we understand this fully yet, but you can see it's characterized by these giant cells, but also a cuff of lymphocytes, and then destruction of the tissues in the artery. All right, Russell, what do you think this, what do you think's going on here? So, what do you think this could be? It could be like a healer arthritis or something that's been treated for years. Exactly, so this is the so-called healer arthritis. And the toughest thing about temporal arthritis is you want to do the biopsy early on. And so, if you suspect someone has temporal arthritis, they've got a high sedrate, they've got a high suractive protein, they've got the other symptoms, you don't wait for the biopsy to start them. You start them on treatment right away, but you've got to do the biopsy within seven days. Because you want to have a biopsy-proven diagnosis. Why? Why is it so important to have a biopsy-proven diagnosis? Exactly, you put an 80-year-old on steroids, they have lots of problems with these. And so, you want to make sure you know what you're treating. And so, my biggest beef is you get people out in the community, the patient will have a high sedrate, presume temporal arthritis, then they put them on 40-apprentizone for whatever, for a few months, and then they start having problems, then they refer them here. Well, by then, first of all, 40-apprentizone doesn't treat it adequately, it's not enough. Secondly, by then, it does make it so the biopsy is almost unreadable. So then you do a biopsy, then you have to look and say, okay, well, the muscular media is gone, you lost architecture, this probably was a temporal arthritis or a healal arthritis. So bottom line is, if you're going to make that diagnosis and treat somebody, do the biopsy, that's really important. So don't just say, well, I'll kind of start them on a low dose. Don't do that, it doesn't really treat it. And it also doesn't give you diagnosis. And so then the patient comes in, they have aseptic necrosis of the hip, they get psychotic from the steroids, they have bleeding ulcers, then what do you do? And so you gotta know what your diagnosis is before you start treating them. All right, Nico, we're looking here, what are we seeing here? All right, so here you've got maybe some subtle swelling here and then here, that probably looks normal. So again, some subtle focal swelling, a little bit superiorly, a little bit nasally. What would you worry about here? Well, it's in the differential. MS would be in the differential. What if this person's 75? Yeah, so this is what, when we look at anterior schemic optic neuropathy, there can be arteritic and non-arteritic. And thank goodness, non-arteritic is most common. And so this is the most common one. Patient wakes up in the morning and they say, wow, I just can't see half my vision is wiped out. And they'll say, well, half my vision is wiped out. So they'll usually complain of that and then they wake up in the morning. And so this is the so-called AION, it's anterior schemic optic neuropathy. And usually, at least the theory is, is you've got a disc at risk, you've got some arteriosclerosis already and then the patient's blood pressure dips four AM before they wake up. Then they wake up and sure enough, they have this altitude, no visual field loss from this. And so this is, when you look at it, it's very subtle. This is one of the things you look inside. And of course, Dr. DeGree and Warner can look in and see this all the time, but mere mortals, we often look in and say, I don't know, it looks kind of normal. And they'll immediately say, no. So they ever show you an optic nerve immediately say, well, I think that disc is maybe fuzzy there. So don't ever call anything normal, okay? And sure enough, what can happen is, is when you get a blockage of one of the arteries, now I forgot to mention when we were talking about the normal optic nerve head, optic nerve head blood supply. Oh, that's a good one, Renee. What's the normal blood supply of the optic nerve head? Okay, okay. When you look at the blood supply to the optic nerve head, actually the, oh wow, this isn't even good evening, this is good night. Good night, okay. That's all right, we'll ask you double questions. We'll ask you double questions just to make up for it. So when you're looking at the importance of the blood supply of the optic nerve head, the central retinal artery is very small. It does hardly anything at all. And those little P.O. vessels don't do much. The main blood supply of the optic nerve head is those short posterior ciliary arteries. And so when the ophthalmic artery comes into the orbit, it gives a branch that goes through the nerve and becomes the central retinal artery, but it gives multiple small branches that surround the optic nerve, the short posterior ciliary arteries. And there's a lot of redundancy in there, and those are the ones that give most of the blood supply to the optic nerve head. And so when you get an anterior schemic optic neuropathy, those are the ones that are affected. And you can see right here, this is one where it's already happened, because if you look, you see this optic nerve here has got some fibers and maybe here, but look at this, this is all just necrotic and wiped out. So you get ischemia here, where one of the short posterior ciliary arteries is blocked off. So that's your anterior ischemic optic neuropathy, or AION. All right, what do we see in here, Jack? You're speaking so softly, I'm not hearing you. Yes, because there's not a lot of information about the operation. Well, you can say again, just describe what you see. Yeah, look at those edges. They're kind of fuzzy and obscured. Maybe it's just a little bit, I don't know if it's elevated or it's just fuzzy. It's just not right. Again, like we'd said before, what if this is a 20-year-old and they woke up, not woke up, they just noticed they're not seeing a lot of the eye and it's weird, it kind of hurts when they move their eye around. Yeah, so you'd worry about optic neuritis or you'd worry about demyelining disease, optic neuritis. And so this indeed turns out to be a patient who has optic neuritis. And so what's the main neurologic disease we worry about associated with optic neuritis? Multiple sclerosis, so you worry about MS. And so when you guys do your neuroop, they're gonna pound you about the studies of the treatment of optic neuritis. And it's interesting in that we used to treat people with optic neuritis, just give them oral steroids. And what they found when they studied it is that's actually not only doesn't help, it may even be slightly detrimental. And so when you see some with a true acute optic neuritis, what you wanna do is you wanna hit them with high dose IV steroids, then you can taper them to oral steroids. And when you do that, it will speed the recovery of the optic neuritis. But interestingly enough, if you go out far enough, it doesn't make that much difference in vision. So six months out, you know, these eventually recover and people do okay, but it speeds their recovery quite a bit when you do the IV steroids. The second thing it does is people have found it delays the onset of MS, which is really interesting. And so when you blast these people with IV steroids in a pretty high dose, believe it or not, it will like put off their eventual showing up of MS-like lesions. And so there's been several really good studies. And so when you guys do neuro, you better know these studies because they're gonna ask you. And so this is an optic nerve in cross-section. And what you end up getting is you get this focal area of demyelination loss. And so here's your normal nerve here, and you've got focal demyelination here. And then when you look at this in longitudinal section, here's your laminar crevice or your optic nerve. Right in here, you've got focal loss of tissue here. So it's not usually the whole nerve that's affected. You can get these focal loss. And then eventually the swelling goes down and they'll recover, but you'll still get some permanent loss right there. And this is end stage of anything. So this could be an ischemic optic neuropathy. This could have been demyelination. So, Nick, what do we see in here that's different from the other pictures we've seen? Exactly. And so what causes the arachnoid space to be bigger? All right, so if the space is bigger and it's not because it's pushing out, let's say that the... Oh, it's because it's... Exactly, it's happened is the nerve itself is shrunk. And so this is an atrophy nerve from whatever reason. So you can get atrophy from ischemia, demyelination. And so this is an atrophic nerve and look at the widening of the subarachnoid space. And so that's why you end up getting this and that's an atrophic nerve. Okay, Julia, what are we seeing right here? Look at that light reflex. So definitely that left eye is lower. Look at the fullness there. So what does that tell you? Yeah, so that eye is pushing out and down so you'd be concerned about a normal mass. What do you make of the age of this patient? Yeah, so she's like 12, 13 years old. And so in a young person, what would we worry about if we see, it looks like a mass in the orbit that's kind of pushing the eye out and maybe down a little bit, okay? So we look inside this child's eye and what do we see here? So you see these little striae right here. What does that tell you? That there's... Okay, and where would that mass be located? On the nerve or in the muscle cone? That's the important thing. So when you start to see striae like this, that means there's something in the muscle cone pushing in, in the optic nerve or maybe there's a growth that's there. We're gonna talk about these lesions next week. But the other thing though is what's interesting is if you take a hundred people with these folds, these coroidal folds they call them, what's the most common etiology? It's actually hyperopia, which is interesting. Yeah, so when you see these you go, oh my God, there's a tumor inside the eye, but you look at them and almost half of them are just a short, flat eye on the posterior surface. And so you do have to do a scan to make sure, but roll out that there's a lesion in there. And this is what we don't want to happen. So Reese, what's going on right here? This is when I forgot to set the gain on the camera because this nerve was so white you had to wear sunglasses when you looked at it. So what is that indicative of? Yeah, so this is an atrophic optic nerve. This nerve has been completely wiped out by a lesion that is posterior to the globe there. All right, so Eileen, we can ask at least two or three questions here to catch you up. So we're looking at a scan right here and we're looking at the scan of this eye right here. What is going on back here? Okay, and looking at the pattern of that mass, what would we call that? Exactly, it's a fusiform or even like a big sausage-like. And so that's indicative of a lesion not surrounding the optic nerve but actually inside of the optic nerve. And so you get this fusiform growth and when you remove one of these, here's the nerve here and look at this. Here's the optic nerve sheath. So this thing is actually growing from the nerve itself and what do we call this? Say this was that same child, actually it was. This was that first child that we showed. The optic nerve glioma. Okay, optic nerve glioma. So what cells give rise to an optic nerve glioma? Exactly, so it's the astrocytes within the nerve that give rise to these. And so technically when we grade astrocytomas, we grade them from grade one to grade four. You know, grade four is a severe brain tumor that sadly most people die of when they get it. So this is a grade one astrocytoma, an optic nerve glioma. And in fact, a lot of people call this a juvenile pylosidic astrocytoma. And Eileen, what does pylosidic mean? Yeah, so hair-like. Hair-like, so when you look at it at low power, it's almost got like little wispy hairs on there. Now this is what it looks like at gross examination. So when you go to that meeting, please tell them we, all of us here, but the administration has to be very realistic with students. That I think is key because that has kind of faded the last few years. And so I think that's a good thing to stress. Well, the board sport changed. I was just looking at it. So in 2010, the average board sport of unmatched applicants was 210. And then this year it was like 229. Yeah, it's unbelievable. That's why I said I feel really bad for anybody applying for the match. And I feel scary times. Okay, so this is, you see this tumor growing from within the nerve. I'm really happy because I wouldn't have matched this year. So I feel really glad that I don't have to do this. Okay, and I wasn't gonna say neither would half of you, but no, no, no, no, I won't say. So all right, so when we look at, this is where the term hair-like pylosidic comes up. So juvenile pylosidic astrocytoma, you've got these little tiny, wispy-looking proliferation of astrocytes. So it looks hair-like. Now, as we're looking through here, yeah, Eileen, I'm making up for it here because you missed like three questions coming out. What the heck are these pink things here amongst these little benign-appearing hair-like astrocytes? Nope, I'll show you a close-up of one of them. They're actually intracytoplasmic eosinophilic bodies. What are these called? See, when you come in the middle of the night, your brain doesn't work as well and you're sleepy. Well, all of that, I failed to review with you. These are called Rosenthal fibers, okay? So Rosenthal fibers, and they're just like, almost like garbage buildup in the cytoplasm of these astrocytes, very common in these. Now, people would argue that this is not really even a tumor. They almost call this a benign growth because when you look at it, these will grow in the optic nerve itself, but they even will start back at the chiasm and you'll see molding of the bone around them when they're coming into the orbit. And so some people would say these are even congenital or these are relatively benign, but just because they're not malignant, they can cause a lot of damage because you can imagine what that's gonna do to the optic nerve itself. The problem with lesions like this, in fact, any optic nerve lesion is that, what do you do? Okay, you cut them out while the eye goes blind. You leave them in place while the eye goes blind. You know, you treat them with radiation, the eye goes blind, but maybe later. And so these are really tough to look at. So a lot of it depends on how far they've extended back. You know, are they threatening the other eye? You know, are they going into the chiasm? And so these are difficult. People have looked at focused in radiation to try to treat these. So tough to treat because again, when they're of a low grade lesion, not really mitosing much, they just don't respond real well to treatment. And here you can see some normal optic nerve here, and then you see this proliferation of these astrocytes here, this little hair-like astrocytoma. Okay. Actually, why would I show this picture when I'm talking about astrocytomas lobe? What the heck is this? It's a segue into our next topic. You see these lamellar, kind of concretion-looking things here at the outside edge of this lesion. These are findings that we will often see in meningiomens. And so you have to be really careful if you're not sure what the diagnosis is and say somebody goes in and they do a very superficial biopsy of the optic nerve, you can get reactive proliferation of meninges on the surface of these astrocytomas. So if you go in and you just do a tiny biopsy on the surface and you get this, you're gonna say, oh my God, it's a meningioma. The reason that that's important is when you have an optic nerve tumor that's outside of the normal age range, it behaves differently. So if you have a glioma in a kid, it behaves one way. If you get an optic nerve glioma in an adult, all bets are off. Same thing with a meningioma. You get a meningioma in a 70-year-old, they behave the standard way. You get a meningioma in a younger person, they behave differently. So you want to make darn well sure when you do a biopsy that you get enough tissue underneath it that you can call it a astrocytoma optic nerve glioma, not a meningioma. And here again, you can see overlying proliferation of meninges. So very, very tricky if you do a superficial biopsy. Okay, Russell, what do we see in here? Yeah, exactly, Greek, maybe Italian. See the mustache? You can always make jokes about your own kind. That's a loud, so. I thought it was normal when, all Greek grandmothers have little mustaches, and so when they kiss you when you were a child, you get that little tickle from the mustache. So that's normal. All right. It's a little hyperglobus, a little bit of, you can get the idea that that globe is coming out towards you. So it's a proptotic, and there's some edema underneath here, and then we look inside and we see this. What is this? Okay, and we call this an optociliary shunt. What does that signify? Exactly, so if you've got something around the nerve slowly squeezing it down, it's a slow process, you can actually get little vascular channels dilate and try to get blood out through that still. You'll see these sometimes in old central vein occlusions too, but these are optociliary shunts, and they're indicative of a compressive, slowly compressive optic nerve lesion. All right, we do a scan here, Nico. What do we see in here on this scan? What's that pattern called when we see a thickening here and maybe a little bit over here? Exactly, that's a so-called tram track. Have you ever seen a tram at a ski area? It's got the two wires and then the one in the middle where the tram goes up, and so you see the optic nerve itself down the middle of this, it's narrow, but it looks okay, and you see that the lesion is actually around the nerve, surrounding the nerve, so the so-called tram check sign. Here's a severe one. This was an exenteration, and you can see a little nerve back here, globe up here. Look at that huge lesion going here. So this is as big as they get. Now, what kind of cells are these? What kind of tumor did we say causes the tram track sign? Meningeoma. Meningeoma, so when you get meningeoma cells, these often look almost like squamous cells in that you see a nucleus with multiple nuclei, but you see this large pink cytoplasm, and they tend to gather in these big clumps. And so they tend to clump right here, and you can see again, this almost looks like a sheet of squamous cells. You know, again, they've got this clumped chromatin, multiple nuclei, but pink cytoplasm, and the classic feature is they form these concentric lamellae that have hyalininum, but also have calcium in it. What do we call these? Somomobodies, and how do we spell it? PS. Exactly, somoma, PS, and there's a double M in there, so if you can spell it right, good for you. So somomobodies are the classic findings that you see, these kind of onion skim, concentric lamellar deposits in there, and then you've got the meningothelial cells in between. Okay, we've got a lesion here, kind of along the optic nerve, it's pushing things forward, maybe you've got even some caroidal folds there. What the heck could this be, Renee? Exactly, and so what's the other word that we can use for neurolemoma? Schwannoma, exactly. So schwannoma or neurolemoma, that's another one, spell neuro, neurolymoma, that's a fun one to spell too. So what you need to remember is rarely you can get schwannomas, there are Schwann cells near the optic nerve and around the optic nerve, and so rarely you can get these Schwann cells tumors within the muscle cone, and what are the two different ways Schwann cells proliferate that you need to know about? All right, so what does Antonie A characterize by? All right, so you see this kind of swirling, fascicular, spindly pattern to it. This is Antonie A, so interestingly enough, Antonie was not Greek and was not either English or German, Austrian, it was actually Italian, so it's, you know, up-down pathology, one of the Italians actually describes something, so Antonie A, swirling, fascicular, spindle-shaped proliferation, and then what's the other one? The second one is Antonie B. Antonie B, and so they call this myxoid, meaning there's like pale stuff in there. You can have little focal areas of deposits of different stuff with the cells in between, and so these are the schwannomas, neuro, neurolymomas, very rare, but they can occur also in the area adjacent to the optic nerve. All right, so we say goodbye to Edinburgh Castle, which is right there. Next week we have orbit, so read, read your orbit. All right, okay.