 I read the part in the Academy's home study book about optic nerve. We're a little bit out of there. We're starting next week. We'll kind of go in order again later on, et cetera, but today's optic nerve. But we can't go until we talk a little bit about where I travel. So again, this is Milano. This is what they've taken one of the old buildings and they're made into a fancy upscale shopping district. This is Los Cala. It's the famous opera house in Milano. And this is the inside. You weren't supposed to sneak in and take pictures of it anyway. So this is what the famous opera house looks like. They've actually got a museum opera next to it, which is pretty interesting. And of course, you can't go to Milano without seeing a statue of Leonardo da Vinci. This is da Vinci right here. And sadly, we lost two giants of ophthalmology in the last two years. We lost Alan Crandall and we lost Roger Steiner. So he was one of the true giants of ophthalmology. Sadly, he passed away a couple of years ago also. All right, we're going to talk about optic nerve today. So this is a nice picture of just an ophthalmoscopic view of a nice, normal optic nerve. You see the color? It's kind of a yellow, pink, hard to tell. But you'll know what the normal color is when you see the abnormal color. Because when it's pale, it looks white. When it's in gorge, it looks more rare, more pink. You see the sharp borders, no sign of elevation. You see the central retinal artery and vein coming out here. All right, let's just start. We see something new on every picture that we see. What can you tell me about this person looking at this picture? Look closely. I've shown this for 10 years and I just noticed it now. They have arterial sclerosis. Look at that arterial. It's an arterial sclerosis. All right. OK, so here's the optic nerve. Now we're going to start on this side just to confuse you guys. So what kind of stain are we doing right here? Trichrome. And so what is trichrome stain? What is the pink stain and what is the blue stain? Pink is. No, you got it right. I can't remember what the blue does. The blue is more connective tissue. Pink is more mesenchymal tissue. So this is the optic nerve seen in sagittal section. You can see the fibers themselves are pink. And you can see that the lining on the outside and the connective tissue and the sclera there is blue. So that's why I show this trichrome. So the analogy I like to use, remember, the optic nerve is a fiber optic cable. So each axon, as it leaves that ganglion cell, comes through the lamina crevrosa. Just posterior to the lamina crevrosa, it becomes myliny. So that is a single optic cable fiber that is wrapped in a little bit of plastic. Then these form columns. And so each of these columns have these little PL septae between them. So that's the bundles of the fiber optic cables. Last but not least, it's wrapped in an optic nerve sheath, which is the steel tube that the cable's in before they bury it in the ground. So when they bring that brand new Google cable to your neighborhood, that's what they're putting into the ground. So each axon gets myelinated posterior to lamina crevrosa. They form bundles with PL septae in between them. And then the whole thing is wrapped up with the optic nerve sheath. Let's go back one. And here you can see it in cross-section. Optic nerve sheath, arachnoid and subarachnoid space, and the columns of the axons. OK, what are these two vessels right here? That would be the social retinal artery and the sphincter. And why would I show that? Just for the truncates. Remember, they share a common abntiscial sheath. So as we talked about last week, central retinal artery occlusion is due to arterial sclerosis. Central retinal vein occlusion is due to arterial sclerosis. And so because they share a common abntiscial sheath here. What am I showing right here? Another trichromatostein. So the connective tissues in blue, the mesenchymal tissue is in red. What part of the nerve am I showing here? What am I highlighting here? I think so the sheath and then the arachnoid space, subarachnoid space, and the granulation is right beneath it. Exactly. So here you see the optic nerve sheath. There it is. Vibrous connective tissue. And then underlying it, the arachnoid granulations, the subarachnoid space where the cerebrospinal fluid flows. And then lastly, the pia mater. And here you can see the pia wrapping around these columns of axons. And here you can see it longitudinally. Here are the axons. Here's the little pia mater. Now, what cells live in the optic nerve aside from the axons of the optic nerve fibers? So there are astrocytes and oligodendrocytes. So what do the oligodendrocytes do? They help myelin to produce myelin. Yeah, they don't help. They do. So they do do the myelin. So the oligodendrocytes do the myelin that surrounds the optic nerve. And then the astrocytes live in here. And there are actually some scattered little microglue cells in there. We don't understand perfectly, but those are the cells that live in the optic nerve. All right, once again, we kind of talked about this. Centro-Rentinal artery, Centro-Rentinal vein. As they go in, they come together. And the closer you get to the optic nerve hand, the closer they are. And they share the common adventutial sheet. OK, what am I showing here? So I'm going to call it one of those photo kind of temporally that we're going to call this sclera. And then. Ah, maybe this isn't in the book. I'm thinking, not called, but more like optic nerve hypoplasia. Exactly. And so oftentimes you'll look in and you'll see the nerve looks small, very small. And then you'll see this little halo around it. So it's like the nerve is just smaller. So it's called optic nerve hypoplasia. Is that clinically relevant, usually? Usually, like, isn't. Yeah, usually not. But interestingly, it can be familial. So if not uncommon, you'll see a younger person with optic nerve hypoplasia. And you'll just ask, you know, mom, hey, can we dilate you and look inside? And sure enough, oftentimes the mom will have that. OK, so I'm making a total sexist comment here. What did I say? Mom. I said to the mom, do the dads usually bring the kids in? No, usually mom who brings them in. So I'm not just making a comment. I'm not saying anything, but you just need mom. And so you will ask the parent if you can dilate them and look inside. And oftentimes it's familial. What are we looking at here? So this is an optic nerve. All right, so what is a coloboma? It's a descent of what the, during embryology, when the optic nerve doesn't close fully. And so it's like a keyhole defect. So if you remember from embryology, you initially have a fissure in the optic vesicles that are coming out and invaginates and the vessels go in, but eventually it fuses. And when it fuses, it fuses at the equator and goes anterior and goes posterior. So where the fusion is incomplete, and notice it's inferior here, then you'll often get a coloboma. And so you'll get improper fusion of that original optic vesicle. And you can see that there's a partial nerve here. And then you've got this area where it doesn't form forming a coloboma. And now sometimes it can be very big in dramatic. So you can see this is the optic nerve right here and this is huge, inferior, maybe slightly temporal coloboma. If you can imagine that has a very big, very significant effects on vision. So optic nerve coloboma. Now, what the heck is this thing? Let's go. Yeah, that is a flower and it's called a morning glory. And the reason I wanted to show that is a very large optic nerve coloboma often will pooch out away from you. So when you look in there with your 90s, it's like looking down a trumpet horn or looking down a morning glory flower. So that when you get a severe optic nerve coloboma, it's called a morning glory syndrome. And that's why it's the flower morning glory, which kind of looks like a white trumpet horn. And that's basically what you're seeing when you're looking down into this large coloboma in the so-called morning glory defect. All right, what do we see in right here? So temporarily this, there seems to be a gray hatch. Do you think that could be? I think it could be like an optic nerve. All right, let's see. And indeed, here it is. So what exactly is an optic nerve pit? I'm guessing probably like those. Exactly. So it's interesting in that you can sometimes get even like vitreous material going down into this optic nerve pit. But the other thing it does is you can sometimes get cerebral spinal fluid leaking out underneath where that pit is. And then it's usually temporarily. So you can have to get cerebral fluid temporarily from an optic nerve pit. These are difficult to treat because you can't go in there and laser it because you'll destroy those fibers coming in temporarily. And so it's very difficult once that leaks fluid to get that to go away. And you get some focal visual field defects in that area where the optic nerve pit is. All right, what are we looking at here? It looks like there's kind of that fuse might be on the left of your aspect that's growing there, which would be close to here in the optic part. All right, so this is a severe example. Usually I don't look that severe, but sometimes what'll happen, and this happened very early in embryology when the axons start to get myelinated. For some reason, those oligodendrocytes end up more forward to the laminocurobrosa rather than posterior. And you'll get this anterior myelination. Now, interestingly enough, those nerve fibers still work pretty well. So you may have an enlarged blind spot in that area when you do visual field tests, but the patients can still have normal vision. This is more of a curiosity. And so this is myelinated optic nerve fibers. They're both made for both. It's still going to be a big business. You know, it's very uncommon to involve the maculence. Usually located more around the optic nerve or at least closer to the optic nerve. So myelination in the macule is extremely uncommon. All right, what are we seeing right here? I don't know if it looks like there's... All right, so some lumpy, bumpy areas here. Do you think those could be? I'm not a head drusen. All right, so it's very important that you recognize optic nerve drusen because if you were, say, you're looking at a non-diadated pupil with a direct ophthalmoscope, this looks like papillodema. And so we've actually seen patients who undergo workouts for papillodema and it turns out to be optic nerve head drusen. And so the key one you look at is those vessels are not engorged. You've got this little lumpy, bumpy pattern and there's some whitening to it. Now, sometimes these could be pretty prominent. I mean, even an intern can see these. So maybe even a student, I mean, this is really prominent. So a fellow, you know. So you can look right here, you see this lumpy, bumpy pattern here and they tend to be unilateral or bilateral. Yeah. It's really the other way. They're most commonly bilateral. They can be asymmetrical. And so sometimes you can look at them and you see one in one eye. The other eye, maybe, maybe not. So they can be asymmetric, but they're usually bilateral. And this shows what can happen in the long term. I mean, this is very uncommon that this happens, but you can actually get pretty significant atrophy. Look at those vessels, how atrophic they are and that retinous atrophy from severe drusen. It's really uncommon that drusen will do it that badly, but you can often get focal arcuate visual field defects where the axons pass over the drusen. And you wanna see this is drusen and this is papillodema. You can see sometimes it's really hard to tell the two apart. So it can be really difficult to discern the difference. So what are we showing right here? Did you know that? No. No. Exactly. So what makes optic nerve head drusen show up on a CT scan? Calcium. And so these are actually calcified deposits. And so if you do a CT scan, they'll show up real nicely on there. And this shows you, I'm sorry, I know this is a really high power, but this isn't an optic nerve head cut right through where a drusen is. And no, it sits anterior to the lumbar fibrosis, which you've got this calcified fibrotic area right here where the drusen is. And if we look at the pathology, again, here's lumbar fibrosis, optic nerve head, these are very calcified. So that magenta and reddish purple material staining on there is calcium. It's just on a straight H&E stain. So you get these calcified drusen that sit on there. And the key thing with the drusen is recognize them. What's a test you can do in the clinic that you could even do yourself? You don't need anything special to really cement the diagnosis. Ultrasound, what kind? B-scan, all right, because these have calcium in it. Well, you could do it on an A-scan also, but if you just put a B-scan on there, get the drusen right in the middle of it, then start turning the gain down. And what you'll find is that the globe slowly disappears and the drusen still lights up. Because remember, the sound waves hit that calcium, it bounces right back at you. And so you'll have really high signal right there where that is, so just put a B-scan on there real quick and you can make the diagnosis without having to have a person get a lot of other tests. What do you think is, but I think in neuroclinic, a lot of the time they do OCT, EDI, do you think that one is like better than the other? Well, no, they're both good. You can also do an OCT because an OCT will show this off. It's just when you don't, you know, the nice thing about a B-scan is we don't all have OCT sitting in our clinic, but you can put a B-scan on there really quick, just have it close to the eye and find that optic nerve. Well, you'll get that signal as you can do it in about two minutes in your clinic. But yeah, OCT will show them up also. And this just shows you a close up. There's the deposits, here's the optic nerve head and so these calcified drusen. All right, what do we see in right here? Papillodema? What is it? Is it papillodema? Can you tell me that diagnosis on this picture? Aha, board question. This got me once on oral boards, it did, so don't. Okay, papillodema by definition is optic nerve swelling secondary to increase intraocular pressure, which means it's bilateral, which means you know there's high pressure. And so if you're showing a single picture on oral boards, don't say papillodema, don't say optic nerve swelling. Now all right, so indeed it probably is papillodema, but boy, I got nailed by the guy that was doing the oral boards on that. Oh, this is papillodema, how do you know that? Okay, optic nerve swelling, so. But this is indeed a nice picture of optic nerve swelling and the most common cause would be papillodema. So what are the features that you see on here that tells you that? Sure, it's raised. All right, so you notice, I guess a word that you may want to use is indistinct optic nerve margins, you don't have that sharp border, it looks raised, looks elevated right here, and so it's got the suspicion. Of course, when you're looking in with a 90 diopter, we have that depth perception, you can actually see that it will be elevated. And so again, when you're taking oral boards, you want to describe it, and J. Lawton Smith was the old neuro-ophthalmologist at Baskin-Paul, and he used to do these things called audio tapes, you guys don't know what they are, but they were these little cassette tapes before the internet, you could put them in your car when you were stuck in traffic, driving to work, and he would do these tapes, and it was very informative, but he was from a little tiny town in the Florida Panhandle and had a real heavy Southern accent, and he would love to have his sayings, and one of his sayings is describe that picture like you're describing it to a blind man. And so you'd say, what the heck does that mean? Well, that's really a good term because you want to be able to describe that so that by your description, somebody knows what you're talking about. And so you would say it's a picture of the optic nerve, the margins are indistinct, it's fuzzy, it looks like it's a little bit elevated, so that would raise the suspicion for apllidema. Now this shows you a little bit more, I don't know, we're just gonna swing back this way. All right, what are we seeing in this one? What else can you have that this picture shows with severe, say, apllidema? Exactly, so you see these flame hemorrhages. What are the vessels doing? Exactly, so when you get severe apllidema, you get congestion, you can get back up of blood, and so you get the vessels become tortuous, you get these superficial flame hemorrhages. So this is significant apllidema, very severe apllidema. And when we look at it pathologically, so this is where the optic nerve head goes across, this is the lamina crevosa, look how thick that optic nerve head is. So it's markedly thick, but not only that, these vessels are engorged, and look at the little flame hemorrhages on the surface. So very swollen optic nerve head, engorged vessels, small flame hemorrhages on the surface. So consistent with apllidema, optic nerve swelling, secondary to increase cerebral spinal fluid pressure. And this actually shows you the lamina crevosa bowing forward, so you can really get a dramatic forward bowing in severe apllidema. All right, what are we looking at right here? This is a little bit more subtle, what could this be? Okay, so always keep that in your mind in the differential diagnosis. When you see swollen nerve, especially if it's just unilateral, then you want to look at the age of the patient. Younger is it older, and you want to say, okay, what's in your differential diagnosis? Apllidema is in the differential diagnosis, but also things like optic neuritis, inflammatory lesions that can cause acutely swelling of the nerve head right there. Why am I showing you this picture? What's the other thing that's in the differential diagnosis beside inflammatory and swelling? I just see answers. Exactly, so ischemia. So that's the third major category you want to look at. So oftentimes ischemia, the nerve doesn't look swollen, but if you can see a swollen nerve, let's say it's an old person, and they say, yeah, I woke up this morning and I just can't see out of that eye. And you look in and you see that swelling right there. So you worry about ischemic optic neuropathy. What are the two main categories of ischemic optic neuropathy? It's anterior. Beyond that, anterior optic neuropathy. Exactly, so you want to always not miss an arteritic form of anterior ischemic optic neuropathy that boasts of the non-arteritic form. So why am I showing you this picture? And this is a nice looking one, and so I hope my temporality looks like this now. Not too much moochies or crown burgers here, but a lot of cholesterol in there. Impact muscular media and tech internal lastic lamina. That's a nice, healthy, non-inflamed optic nerve. As opposed to this, what do we see in here? Think I want layer? I'm sorry, I don't know. Big layer, thickened into it. Look at that, that's all that's left of the lumen is that little teeny, tiny slit there. And internal lastic lamina just gone. And as we go to higher power, what characterizes these? Giant cells. Some people even may call these giant cell arteritis. You can even see a couple of lymphocytes. Sometimes you don't see it with you in cells. Sometimes you don't see giant cells. But these are truly an ophthalmic emergency because you don't want to miss one of these because people can have severe bilateral vision loss. And so if you are suspecting temporal arteritis, treat them with steroids immediately and do the biopsy within seven days. And that's important. You do have that biopsy diagnosis, but don't wait for that. If you have suspicion, say their set rate is high, their seric protein is high, they're having other symptoms. Treat them with steroids now and then get them scheduled for a temporal artery biopsy. What the heck is this? It is everybody, right? It's gonna be high and back, I don't know, okay. This looks like another temporal artery biopsy. The structures have still kind of been destroyed, but I don't see any active inflammatory cells. So what do we call this? This is healed arteritis or burned out. Yeah, exactly. So healed arteritis or burned out arteritis, it's where a patient has had temporal arteritis, but it's been treated or it burned out. And so if you look right here, you see the lumen is still really narrow, massive, intimal thickening. But look, the internal, the muscular media completely gone. Just chewed up right here. But no acute inflammation. So this is what's called a healed arteritis or an arteritis that is burned out. All right, we're looking at this right here. What do we see in here? What about the optic nerve? There appears to be pallor and blurring of this margin. So again, really subtle. And these are tough. When you get to neuroclinic, you look inside and you look at these and you say, okay, maybe some little swelling and maybe a little inflammation on this. So again, what's your differential? Mostly the optic disc, edema differential that we've discussed so far, but given that it's not real, I would be worried about something inflammatory. So that could be enteroschemic optic nerve. Exactly. So when you're looking at a patient like this, you always wanna be going through your mind, what are the potential categories? Could it be ischemic? Could it be inflammatory? Could it be swelling? And so that's always gonna be in your differential diagnosis. And then other factors will come up. Is this a 70 year old vascular pathic guy? Is this a 20 year old college student? And those things will also kind of help guide what you're gonna be looking at. So let's say for argument purposes, this is a younger person. And we go ahead and I take it back. Sorry, let's say this is a 70 year old vascular path. And we wanna go ahead and we look at the optic nerve. What do we see in the optic nerve head right here? Just fluid and congestion of the actual optic nerve head. Some swelling. Actually, that isn't even swelling. That is the nerve is just wiped out. So that is wiped out nerve. So this is a patient who had anterior ischemic optic neuropathy, but non-artoretic. Well, this could be arthritic also, but this is isemia. And so if you really look right here, there's a few normal fibers out here, but these are all white and have been wiped out. So this is what ischemic optic neuropathy does to you. It really wipes out that anterior optic nerve right there. So this is an end stage in your ischemic optic neuropathy, either arthritic or non-artoretic. Both could look like this. All right, once again, continuing our theme. This also looks like blurred disc margins and maybe looks a little elevated as well. So I'm worried about optic nerve edema. So is it just me or did those last three optic nerve pictures I showed you all look about the same? So again, this is very tough to tell this differential diagnosis. So again, it's kind of swollen, maybe a little bit edematous. And could it be papillodemus here? Could it be ischemia? Yes, could it be inflammatory? So those are always what you wanna keep in the back of your mind when you're looking at these optic nerve pictures. And now this is a cross-section of a nerve. Now, why is this different than the last one we showed? There's the lower left quadrant. Looks like it's missing nerve tissue or axons. So I don't know if that's like a focal area of atrophy. Exactly, so when you've got a little focal area like this, this could actually be a sign of optic neuropathy. So this can be inflammatory demyeliny. So right here, you get this focal wedge of atrophy of the nerve. So that can be a person who has got not ischemic, but inflammatory optic neuropathy. And so in an optic neuritis, what is the one thing we worry about if a younger person presents with an acute optic neuritis with the associated condition you're gonna wanna miss? Multiple sclerosis. So interestingly enough, when I was a resident, the association between multiple sclerosis and optic neuritis was still vague and people still argued about it. And since then, there have been some very nice studies that have shown that, yes, in fact, if you have a younger person coming in with acute optic neuritis, you really have to get an MRI scan because you have a surprisingly high amount of people that have an associated MS with that diagnosis. Now, you guys always wanna know the different studies that were done on the treatment of optic neuritis. So know those, especially for boards. You know, in my day, when we thought it maybe was optic neuritis, you give them some oral steroids. And the interesting thing is when they looked at it in the terms of the study, the oral steroids really didn't do anything. In fact, they even made the outcome less good. But if you blast them with high dose IV steroids for about three days and then oral steroid taper, then you can actually help the recovery get quicker and help the symptoms go away quicker. However, if you look at the study as they extended out, after one year, there's really not a lot of difference between the groups. But again, if it were your eyes, they were completely blurry and someone gave you steroids and your vision came back a lot quicker. Yeah, I'd go for that. What's the other thing that the study showed? If you treat them with high dose steroids, anybody beside a quicker recovery, well important. Right back. Exactly, when you get them, when you blast them with high dose IV steroids, you actually reduce the eventual association with that mass. So very important to recognize this and to do it. And here you can see now more of a sagittal cut. If you look right here, so this is demyelinating disease and you can see a focal area where you've got a focal segment and a sagittal cut of the optic nerve that was affected by demyelination. This turned out to be an optic neurons. Now, what does this show? We're seeing the side of the optic nerve. So you can see the optic sheath, the arachnoid infalitions. So what is this showing? What is that normal about this picture? Is the subarachnoid space widened? Exactly, look how wide that subarachnoid space is. So does that mean the subarachnoid space got swollen outward? No, it's optic atrophy. Exactly, so this is an end stage optic atrophy. Now, this doesn't tell you why the optic nerve is atrophy. This could again be ischemia, it could be demyelination, it could be several other things, but bottom line is once you damage that optic nerve, those fibers do not regenerate. This is the second cranial nerve, cranial nerves don't regenerate. So in this point, a central cranial nerve don't regenerate. And so you can see right here that that widening of the subarachnoid space, so this is an optic nerve atrophy. End stage condition of a lot of these, a lot of these issues. What are we seeing right here? See the pupil on the left is dilated to the right. Okay, that would be like the fifth thing I would notice in this picture. What's the first four? Reflexing the left, not the right. Okay, that's the fourth thing. What else are we seeing here? Sure, I can take this one. So, you can tell. That's right, that's a good try. I'm going to tell you about the left eye seems to be low work or so. High will blow much. As a result, there's, I'm not sure if it's real ptosis, but in this case, it could be pseudo ptosis because of the head of the lobes. And the right leg flex to this on your pupil's right eye. See the dead center there and here kind of superior in the zone. And again, maybe I'm hallucinating here, but maybe there's a little bit of fullness there and it's almost as if that eye is down, but maybe even out a little bit. You had that perception on it. That may even be coming out. And how is this patient? What was your question? How is the patient? Yeah, let me know. So this was, you know, an adolescent. Not an older person, a younger person. And we look inside the eye and we're seeing this. The heck is that? There are a lot of lines and the best of those ones is striations. All right, so what causes striations like that when you look inside there? Even this picture of something looks like that. I mean, I don't know if it's striations. I'm worried that there's something impressive. Exactly, so you'd be concerned. Maybe there's some mass occupying lesion in the comb, in the muscle comb pushing forward. And that'll give you these striat. All right, what's the most common cause of these optic nerve striat if you just pick a handful of people and you looked at it? Um, probably a posterior mass or if you can help to protect from small eye or blood. Exactly, which of those is most common? The refractory. Yeah, so by far, when you look at these, you're just, oh my God, an optic nerve tumor. But by far the most common reason is the hypoaropic eye is a little bit smaller, a little flatten on the posterior surface. So these striat don't necessarily mean a space occupying lesion. But again, don't miss that. And so you'd be concerned about that. And you want to be really concerned about that because if you don't catch this early on, this is gonna happen. What's going on right here? So very white or pale atrophic optic nerve there's a lot of vessel attenuation. So if you happen to have a lesion back behind the, you know, in the optic nerve around the optic nerve in that muscle cone, it can lead to significant optic nerve atrophy. And you can see right here, a very atrophic optic nerve due to that lesion. So then we go back and we do this scan. What are we seeing on this scan? We're seeing retroval region. So what would your differential be at that point looking at this picture? It's a little bit neon. And meningioma, obviously a possibility to be a, you know, it's hard to tell, but that's sectional organ right now. That'll look through others, but it could be something more than that's in the mass. But yeah, people. Yeah, when you look at a lesion right here, it is in the optic nerve and you can see it's fairly solid in uniform. So you wouldn't really see that in a vascular lesion and in a meningioma, if you get a good cut, you often don't see this big fusiform lesion. So you see a lesion, it's fat in the middle and it tapers off at the edges. That's usually something that is intrinsic to the optic nerve. And here we actually have that lesion that we removed it. So give it, let's pretend this is actually that first adolescent girl that we showed a picture of. What do you think this is? I mean, in young people, it's more common that they would have like a glioma or... All right, so if you look right here, you can actually see here's part of the optic nerve sheet still overlying that. You see this big fusiform enlargement underlying the optic nerve sheet. So, you know, the most common lesion that looks like this would be an optic nerve glioma and gliomas occur most frequently in children and adolescents, they don't usually occur very often in adults. And so if you look at this, this is what we call bifusiform. You see it, it's at the optic nerve head and then it widens out and then tapers at the end, but you see it is intrinsic to the optic nerve. And so the most common tumor that does this is an astrocytoma or a low-grade glioma. Now, what do we call these? How do we characterize these lesions? I don't think we should. I'm just saying, but sometimes somebody will surprise us and pop up and say something. So if you say, I don't know, I'm a student, that's allowed. Looks kind of almost air-like. Exactly, so when people look at the histopathology, they say it's hair-like, which, you know, pylomines hair. And so basically they call us a pylocytic astrocytoma or a low-grade astrocytoma. So when you grade astrocytoma as grade one is the low-grade optic nerve. Grade four is the severe, you know, glioblastoma in the form of the brain. And so these are mostly grade one and low-grade astrocytomas. Hair-like, pylocytic, which is how the term comes up. And now what exactly are, let's see, we'll go around here. What is this thing right here? And what exactly is a rosenthal fiber? Exactly, so that these big, they're kind of cigar-shaped or oval-shaped, rectangular-shaped, isentrophilic inclusions in the cytoplasm of these low-grade astrocytomas. So they're called rosenthal fibers and they're a real tip-off that this is indeed an astrocytoma. But again, you can kind of see the spindly, hair-shaped nuclei in here too. So low-grade, grade one astrocytoma optic nerve, glioma. And there's a close-up of a nice juicy rosenthal fiber, but there's several of them throughout. So those are the classic findings that you see on histopathology when you look at these low-grade astrocytomas optic nerve gliomas. What the heck am I looking at here? Even or not, these can actually occur not taking over the whole nerve, but can occur in part of the nerve. So this just shows you where it could be confusing and you look at this and say, wow, it looks like it's around the nerve. Maybe this is a meningioma. But if you look closely, you still have this pylocytic hair-like look to them and then still a little bit of normal nerve next to it. Sometimes they're not diffusely involving the nerve. If you kiss them early, it may just be partially involving the nerve. Now what we really worry about is if you go in there and you say, yeah, I'm not sure if this is a glioma. Maybe it's a meningioma and you do a little tiny superficial biopsy to say, all right, let's do a little tiny biopsy so we don't kill the whole nerve and see what this is. And you see these meningiol cells right here, you can get reactive meningiol hyperplasia on the surface of a glioma. So if you're gonna try to make a diagnosis with a biopsy, which is hard because you don't want to just kill the whole nerve and biopsy it, but this looks like meningioma right here. And yeah, believe it or not, this turned out to be a glioma. So you get reactive meningiol hyperplasia, so careful if you're gonna do a biopsy in your territory. And you can see that again right here, that meningiol hyperplasia. All right, what are we looking at here? Yeah, you can see it in the external photograph. I tend to drop the right eye, see right there, focus, to focus that into some of the proptosis. All right, so again, you get the idea that there's a fullness behind the eye and the eye is protruding toward you. So you're quite concerned about that. And now note the patient, how do you think this patient? Yeah, so he's not an adolescent. This patient's probably 70, 75, so it's an older patient, not a younger patient. So that changes your thinking as to what the difference would be. So if you were indeed looking at an intraconal lesion, what would be the most common one in this age group? Meningiomas, remember, glioma, younger, meningioma, older. Now, if you have a tumor that arises outside the normal age group, those usually tend to be more aggressive. I don't know why that is, but say you get a glioma in an older adult, those be aggressive. Ninja home and a child would be very aggressive. They're extremely uncommon, but if you get a tumor that's outside the normal group, you see it and they tend to be more aggressive. Now, we're looking inside the eye, we're seeing this. Let's say that's that same lady. See, there's that shut vessel on the card. So what does an optic nerve shut vessel tell you? It tells you that's one, it's more long-standing and that like the blood flow out of the eyes probably strength played it a little bit. That's why there's a blood vessel growing. Exactly, so if you have a tumor growing around a nerve, slowly squeezing it off, sometimes you can form shut vessels here. So that's a tip off that there's been a long-standing lesion, kind of slowly strangulating that optic nerve. You get shut vessels grow. And here we have the MRI scan. What does the MRI scan show? So around the right eye, there's this mass kind of enveloping the optic nerve and you can clearly see the optic nerve like kind of in the middle of it, but the tumor on either side. So they call this? Tram trac. The tram trac sign. See, and if you've been up to snowbird, you know, the tram and so you look at it, you can see here, you've still got what looks like a nerve in the center and you've got a thickening around the nerve. So as opposed to a glioma, where you've got this diffused fusiform swelling of the entire nerve here on the scan, it looks as if you've got something growing around the nerve, which is a hallmark of meningioma. And here you can see, this is actually an exeneration that they had to do to get all this out of there. But here you can see this huge tumor. Here's the nerve back here still and it's strangulating the tumor on both sides of a very large optic nerve meningioma. All right, so what do we see when we look at the path of meningioma? I think it's just like meningothelial cells. So you see they tend to form these kind of round worlds, these meningothelial cells, they almost look like squamous cells. And so these kind of large, you know, nuclei in the center, pink cytoplasm, meningothelial cells. Sometimes you can get a diffuse sheet of them from meningioma and often you'll get these things right here. What are these things? Somomobodies. Somomobodies, spell it. B-S-A-M-M-A, I mean, that's part of it. Okay, there's a double M in there, but the double M is the second M, not the first M. It's somomobody, okay. Sorry, that's hard to spell. These are just little calcified, kind of concentric, hyalinized deposits that are in here. And so they look like this kind of onion skin, you know, lamellar deposits in here and they're called somomobodies. And these are very common between the meningothelial cells. They're very common in a meningioma that you get the somomobodies that are there. All right, we've got a lesion here. What do we see in here? This looks like a fusiform tumor lesion around the nerve that I guess it would be helpful to see like a coronal view to see it. Exactly, and I apologize, I don't have the coronal view in here, but let's pretend that instead of being in the middle of that nerve, that's kind of next to the nerve or around the nerve. What are other entities that can form gross, you know, intracominal around the nerve? Comeningeoma or schwannoma. All right, and what's another word for schwannoma? Not sure. Lyoma, it's another one that you can't spell either, but again, schwannoma. So let's say this is a schwannoma. And what are the two grading characteristics of a schwannoma that is named after the pathologists who first described it? Antony A and B. All right, so what would this one be? This is Antony A, because it's so close. All right, so Antony, it's like the only thing in epithology that wasn't described by an Austrian or a German. So that Antony was actually an Italian, so. Finally, we're getting Italian subscribers. This is an Antony A and look at the swirling fascicular pattern. So when you get these schwannomas, the Antony A pattern, they tend to form almost like swirling fascicles of these spindle shaped cells. So that's called Antony A, and then obviously this would be Antony B. So what characterizes Antony B? You see a lot of D. What else? So instead of being this densely swirling cellular lesion, you look at it, it's a little bit hyposegular, and it's kind of a mixoid look to it. So you see this kind of whitish look in between. So this is the mixoid pattern, you know? Some people have said maybe the A is a little bit more differentiated than the B, but that's, these are so rare, it's really hard to say that, but these are the two different patterns you do need to know those for boards. And lastly, we say goodbye to the fountains in Milano. Okay, we've got about eight minutes questions, anything regarding optic nerve pathology. You guys know it all? All right, so next week we kind of get back in order, so know you're lit, okay? All right, thanks for your attention.