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ST so that started. Um So tonight, um Welcome to the Neo Sport like series. Um I'm sure that a lot of you have been here before. But for those, I don't know, essentially it's a um group that's been put together to essentially support medical students across different medical schools and different levels of their training and to gain the requisite knowledge in clinical neuranatomy, neuroscience um and to enable them, you know, flourish in these modules within the clinical um practice. Um and just to shed the spotlight on um high yield relevant content that would help us in our clinical and postgraduate years. So our guest speaker for tonight is not really a guest to most of us. Um So it's Doctor Lisa Quinn who has been the head of our neck, um applied head and neck anatomy module as well as many other roles that she's held in the medical school. And I'm excited for the talk tonight and I'm sure you guys are too. So stay tuned. Uh Hello and uh yeah, welcome everybody. Um Really nice to see obviously a spread of phase two, phase two years and uh some familiar names. Um So Um I've checked that. Hopefully you can see uh my slides. I've also got an eye on the chat. So as we go through this session, it's going to be hopefully quite interactive with me throwing questions out to you. Um So please feel free to share kind of your thoughts, your answers into the chat and I can keep an eye on that and that will sort of helps sort of direct where we might go with some of our conversations. Um So obviously, when it comes to uh Neuroanatomy Clinical Neuroanatomy, it's quite a broad subject. Um So I've kind of taken AAA sort of clinical case presentation and used that as a bit of a narrative along which will bring in some of the relevant neuroanatomy that helps us understand um the signs and symptoms that patients might present with, with certain conditions that affect the brain. Um And some of the things that we might find when we're investigating uh those particular types of conditions. Um So I think most people were or had joined before we uh uh kicked off. So just a little reminder, just in case there are any sort of early years students that drop in um to the chat as as we're going through, um I can just keep an eye on that. So as I said, I'm going to present a single clinical case and then through that, we're going to bring in some of the neuroanatomy that you did way back when, um, the early years, um, to help us understand, as I said, some of the features of the presentation and some of the things that we might find on examination or on, on, on investigation and hopefully this will be a bit of, uh, uh, sort of revision recap for most of you, um, rather than anything entirely new. So your case then, um, is a gentleman. Um, we'll call him James, um who's presented following a head injury. Um, he's fallen off er, his motorcycle, uh he's not been wearing his, his helmet, um, and he did have an initial loss of conscious following sort of initial impact um following his head injury. So he was lost consciousness for about a minute before recovering and he, he seemed sort of fully compass when he came around. So he sort of GC S at that point of recovery was 15. He didn't appear confused. Uh, but thereafter he started to complain of uh quite a severe headache. Er, and an hour or so later he begins to vomit and his Glasgow scale drops to about 14. Um, since you are phase two students, um, we're happy with the, the Glasgow coma scale. Um What, what's the lowest score you can have on the G CS? Put a number in the uh in the chat. Yes, excellent. Three. You can never have a zero or G CS, can you? It's three? Wonderful. Um So, so 14 out of 15. So um lightly is, is, is confused. Um So if you're the attending doctor um in A&E when this gentleman arrives, you've done your initial evaluation, um You've checked ABC and you've been evaluating D and identified that there's slightly some sort of intracranial pathology going on. Um and you need to request some urgent imaging. So if you were to be filling in a request form for, for some imaging, what would you request and what might be the sort of various details that you put in the sort of clinical presentation for justifying your your imaging choice? So I'll just give you a few seconds just to again, share your thoughts in the chat. What would you request and what would be kind of the short clinical detail that you'd include on your request? So you're gonna order an X ray, you're gonna order an MRI or AC. Oh excellent. Got a CT head, non contrast CT head. Yeah, any advances on that or any, any disagreements? Excellent love and I love the uh clinical detail that we add in there. We don't want to put too much in, but we need sufficient detail for our radiologists to um look at what we're asking it for. Wonderful. Yes. So a CT head non contrast CT head um would be the appropriate sort of imaging uh in in this scenario, anyone with um a head injury um with certain features that indicate the need for an urgent CT head. Um So obviously being aware of nice guidance or sorts of features that would um raise concern of the need to get a CT head pretty urgently. Um What, what sort of features in in here um Sort of line up with kind of nice guidance for uh requiring a a relatively urgent ct head. There's a couple of things that would tick the boxes um for justifying an urgent ct head. Yeah, the fact that we've got vomiting you vomited twice, we've got um an an initial loss of consciousness and also we've got um current presentation of, of a neurological deficit, haven't we? Um you know, in terms of a an abnormal G CS. So there's plenty in there for, for justification of an urgency to your head without hopefully radiologist uh refusing your uh your request. Um Wonderful. Ok. So we get an urgent, urgent CT um and this is what we find. Um So take just a, a moment just to think before you put anything in the chat so that there's no sort of queuing to, to other people. Um Obviously, you know, most of you are probably able to spot diagnose what the diagnosis is. But I want you to think about some of the terms that might be used to describe what you see. Um And therefore that helps you determine or what to diagnose what it is that's on this, on this image. And also I want you to have a think about which side, um, we're looking at here and is there anything else that's abnormal on this ct other than the, the sort of glaring, the obvious, uh, sort of white, uh, pacification? Um, so have a little think and then start to maybe pop some of your thoughts in the chat. So, based on the history you should hopefully have had in mind that you're concerned that there's been some, uh intracranial pathology, some acute intracranial pathology, uh probably of hemorrhagic in nature and the appearance of this is quite consistent. Um Frankly, I think in the context of um what you are able to see um and and clarify, you can get what you need in this context without using contrast, which is in my mind, why a non noncontrast CT head um is, is entirely appropriate. You don't have to inject anything into the patient. Um Without it, you'd, you'd see the things that you do in the CT head for effectively. So what we thinking, what will be some terms to describe what we see here? Um Lovely. So we've got right um biconcave in the area of the pterion, we've got soft tissue edema, midline shift, um effacement of ventricles because someone else is recognizing that it's midline shift. Um We're happy that this is the right side of the patient. So hopefully, by the time that you spent in uh in phase two, you're, you're getting familiar with sides when it comes to cross sectional imaging. So here we're looking at the right side of the patient. So this is the right side of pathology as is correctly indicated in the chat. Um It's um appearance uh is it by concave, is that quite the right description? So this is um convex, maybe lent form. And um you're right in terms of where it is um would probably be a little bit more um less specific than saying the pterion and maybe more in the region of the temporal bone, which we know is going to be very close to where we we know the terion is. Um but this is probably in the region of um the the the squamous part of the temporal bone. So that flat um aspect of the temporal bone forming the lateral side of your skull. So we've got an area of um would you describe this as hyper or hypodense? So hyper or hypo dense in terms of its, its coloration? So this area here is what I'm referring to. Hopefully, this is what everybody's spotted is that we've got OK. Um We've also got in the overlying scalp, evidence of a scalp hematoma. Um So this side of the bone is is the sort of scalp side. So we've got evidence of bleeding into the scalp tissues. Um And then we've got intracranial hemorrhage that is um uh biconvex, that's, that's biconvex in it or plenty form in shape and the shape of this is quite important in terms of what the likely uh type of intracranial hemorrhage is. Um And yeah, we, we would in, in sort of radiological descriptive terms, this is hyperdense. So it, it, it's it's lighter than the rest of the brain tissue. Um So this is an area of hyperdensity on the right side, um quite sharply demarcated and it's kind of lent forming shape. Um And as some of you rightly identified, there are some secondary um features to note on this in this ct namely being things that suggest midline shift or mass effect. Um So, can anyone um identify other than um the effacement of the ventricles? So that just means effacement of the ventricles means the ventricles are being squashed. Um So normally we would see these kind of two C shaped cavities, black cavities because they're full of su spinal fluid normally um in the center of the brain. And, and in this case, um there has been um s squash squat, the ventricles have been squashed and displaced laterally. Um So midline shift is, is probably more a description of what we see on the ECG. Um In this case, it's caused by the effect of the mass of, of the blood, but you could also get say midline shift if you've got a tumor, for example. Um So here we've got, we've got clear effects of the fact that the mass is, is, is causing an effect of shifting things across the midline. Um One clue is the effacement, the the squashing of, of the ventricles. Um And the other indicator that there's midline shift um is you can just see here two tissue structures. Um Just checking, you can see my cursor, can't you when I'm pointing to things on the slides, just uh uh say yes if that's the case. Um So I know I'm not just randomly pointing at things for myself but not, not showing them to you. Um But here, excellent. Thank you a little bit. Um We can see some, some lateral displacement to the left side of the, of the, of the tissue structures, then we'll know what that is, that's been sort of displaced slightly off the center. Well, I can remember what that tissue structure is. Excellent. Yeah, it's just a folk through, it's one of these dural folds that's inside the skull that acts as a sort of partition for different parts of the brain. And we can see these folds on the brain and they can be useful um in many ways um because um we can look for them on, on CT imaging and see they displaced in any way. So this is just the sort of edge of the false cerebra that we can see has been displaced. So there's a couple of signs on here to the sort of non radiologically trained eye that could give you clues that, that there's some concerning side effects of this of this bleed. And this here is a, is a typical example of an extradural hemorrhage. So hopefully, that's what most of you were thinking when this was, was first shown that you've got blood. So acute blood will always show as bright white to it hyperdense hyperdense on the CT imaging. Um And we've got this particular uh sort of appearance to the shape the collection of that blood, which indicates extra dural hemorrhage with it was secondary complications in, in this gentleman's case. Um And usually, um you know, if you've got an extradural hemorrhage, there's usually an underlying fracture um probably in the region of the temporal bone, the squamous part of the, of the temporal bone. Um ok. Um And, and the history fits with that, doesn't it, the, the history fits with what we would, you know, sort of standard textbook description of, of how an extra dural presents with the initial loss of consciousness followed by a lucid interval and then a rapid deterioration. What what type of blood is this in an extradural? Is this arterial or venous blood most typically? And if you can, yeah, arterial, yeah. So more often than you know, in most cases, this is gonna be an arterial bleed probably from that middle meningeal artery or one of its branches which we know is in close proximity to that squamous part of the temporal bone, the lateral part of the head, the pterion, et cetera. Um So more often than not, they are arterial. So that tells you that there's gonna be quite a degree of pressure to the bleed. Um And it needs quite a degree of pressure to, to strip off the layers of the drawer which occurs during um an extra dural hemorrhage. Um And if you imagine as that as that jaw is peeling off, um and that pressure is accumulating, that's going to cause quite a significant headache. Um So, obviously, patients are going to be complaining of a headache. Um And as this, this, this, this volume is accumulating, the patient may remain lucid. So they may seem, you know, normal neurologically for a period of time. Um and then they very quickly deteriorate. So you've got certain mechanisms, haven't you inside the school that allow you to um control intracranial pressure by altering sort of CSF volumes and venous volumes into the, into the skull. But eventually you reach a point where it tips very quickly. It sort of exceeded the capacity of our our um cerebral mechanisms to counter increasing pressure when you've got extra volume. And so that's where you get that very rapid deterioration. Mhm OK. So with that in mind, then we've got just slightly relation to a couple of other examples um of uh intracranial hemorrhage and you may come across the term um uh extraaxial extraaxial um hemorrhage, go ahead in the chat, an extra axial. What, what does does that mean? What, what, what what kind of differentiating between when we, we talk about extra axial hemorrhage? Ok. So you've got some, some suggestions in the chat. Um I'll come back to your questionnaire Matthew if that's ok. Um So it, it, it's to do with, if you think about all the different things that you can have causing bleed inside the skull, some of that bleeding could occur in the brain tissue itself. So the brain paran come. Um So that might be because of a a ruptured cerebral artery that feeds the brain tissue itself. But also you can get bleeding from blood vessels um that don't bleed directly into the brain tissue itself. So when we talk about extraaxial hemorrhage, we're talking about effectively are subarachnoid are subdurals and are extradural. So these are all intracranial hemorrhages that are occurring inside the skull, but they're not um directly in the brain tissue itself. They're not sort of hemorrhages into the to the cerebrum. Um the the brain tissue. So that's where the extra axial comes from. So you sometimes might see that on CT reporting or in some of the descriptions. Um So when we talk about our extradural, our subdurals and our subarachnoid and they are extraaxial hemorrhages. So what, what do we think between these two then? Um So we start with the one on the, on the left. Um uh Are we happy that that's abnormal? Um We can see that there is a hyperdensity um visible in a particular pattern. Um What do we think is going on with this first one again, pop in the chat. So we've got some suggestions for subarachnoid. And again, why have you recognized or decided that this one's a subarach night? Yeah, there's this, this sort of appearance to it, isn't there? Um Do you know why? Yeah, wonderful. You mentioned systems and, and uh and the, and the star pattern as well as has been mentioned. So, um this is a subarid hemorrhage um as correctly identified. So again, we've got blood in the acute sort of presentation blood is hyperdense. So it looks whiter than the surrounding brain tissue and in a subarachnoid hemorrhage, um quite often your um sort of likely source of bleed is, is, is, is what, what, what's the sort of um likely culprit in a, in a subarachnoid hemorrhage? Yeah, it's usually an aneurysm, a berry aneurysm that's somewhere on one of the blood vessels within the circle of Willis. And if you remember back that circular arterial um arterial circuit is at the base of the brain, isn't it? It sort of sits at the base of the skull underneath the brain. Um And that circle of all, you know, it is the thing that gives you cerebral arteries that go off and, and plumb into the to the parenchyma and supply the supply the brain tissue directly. But where it sits is the circle of Willis and gives off its branches it's within the subarachnoid space. Um And so when we do have subarachnoid hemorrhages, it, it's, it's, it's likely to involve um an aneurysm that that's burst on one of the sort of components of the circle of Willis. And hence, you get bleeding into what are called the basal systems. So, right at the bottom of the base of the brain, the subretina space is, is quite um quite wide relative to the subretina space around the rest of the brain. So you've kind of got a sort of um wider space between the pier and the Arachnoid um at the base of the brain. So that fills with blood when you've got a ruptured aneurysm. Um and that's the appearance as you, as you sort of fill those basal systems at the base of the skull with blood. And, and, and how might someone with a subretina present relative to perhaps some of the descriptors we've used to describe the, the extradural? Yeah. So there's, there's, you know, usually when a vascular event happens, something ruptures or bursts, there's quite a sudden onset of a, of a, of a manifestation of that isn't there. So a very sudden onset of a headache often can be described as the worst headache ever. And because this bleeding is, is close to the to the two inner layers of the meninges, the pia and the arachnoid, which collectively we sometimes call the leal meninges. So if you come across the term lepto meninges, we're referring to the pier and the arachnoid las. Um So meningitis, meningitis affects the pia and the arachnoid layers. Um So in a subarachnoid hemorrhage, that, that blood, the blood in the subarachnoid space is really irritant. So it really irritates the pia and the arachnoid and that is what causes the, the signs of meningism. Um So you've heard of obviously signs of meningism when someone has a meningitis. But also we see some of the signs of meningism when someone has a subarachnoid hemorrhage because the blood is acting as an irritant to those leptomeninges. Um And what might be some of the, the clinical signs that we um may elucidate or the patient may describe that implies meningism. Um But obviously, in this context, the meninges is caused by irritation of blood against those meningeal layers. Yeah. So neck stiffness becomes painful to, to bend the neck. Um They also may describe photophobia. Excellent. Um So, you know, headaches and onset with, you know, presence of things like photophobia, neck stiffness. Um You've got to be quite concerned, haven't you? About a sub rhino hemorrhage? Um And you'd want to ct the head um pretty quickly. Um I don't know if anyone knows off the top of the head, the sort of CT guidance for the time frame within which you want to get a CT head done with reasonably high sensitivity for picking up a subarachnoid. Does anyone know how many hours nice guidance imply. Um So with um with traumatic retinoid hemorrhages, so obviously, you can get bleeding in vessels in other parts within the retinoid space. Um You're probably still gonna get signs of um potentially of, of meningism. It depends, doesn't on how extensive the, the, the blood is. Uh But if you've got blood that that's literally filling, you know, quite extensively into the subarachnoid space, then there's gonna be enough irritation there of the meninges to probably cause all those sort of signs of meningism. Whether it's more common in the traumatic versus the nontraumatic causes of the subarachnoid. I'm not sure. My, my, my guess would be how extensive the bleeding is as to how irritating it is to the meninges. Um So act, um, ideally, you know, if you've got a high clinical suspicion, you want to get them scanned pretty quickly. Um, usually within six hours of symptom onset, not of them arriving in A&E. So you need to know very clear from the history of the point at which they are presented, all their symptoms started. And you want, ideally within six hours, I think before of getting a CT. Um, so that if it's, if it's negative, you can be reasonably confident that it's negative and not necessarily need to do an LP. Whereas if beyond six hours, your CT is negative, um, you would, you would need to do a lumbar puncture, you to be 100% certain that you've ruled out, um, a subarachnoid. Yeah, within six hours of symptoms. Not of when they first presented to a, um, so it's within the, you know, so if they're presented five hours, you know, the headaches after five hours ago, uh, you, you've got an hour to, to, to hopefully get them to have a CT that's actually useful for excluding, um, a subarachnoid. Should it be negative for, for that? Anything beyond that, the sensitivity of the CT picking up blood? Um It, it, it drops. Um So you can't be as sure that you've, you've excluded it with the CT and you'd need to do a lump of puncture because your lumbar puncture taps into the retinoid space, but obviously, uh using the space around the, the, the the spine or the cord recliner. Um And obviously, if there's blood in the space around the brain, that blood is gonna circulate around the entire extent of the subarachnoid space and that's gonna include down and around the spinal cord and the cord recliner. And we can safely access that with AAA lumbar puncture and what we'll be looking for in a lumbar puncture if we were to have to do a lumbar puncture, what what would we look for request on the sample to help us rule in or rule out a sub noise? Yeah. Xanthochromia. Yeah. So the Xanthochromia would include indicate that there's obviously been red blood cell breakdown, which is what creates the bilirubin. Um And you know, the presence of, of there being blood in the subarachnoid space and the fluid indicates that, you know, there's been some bleeding from blood vessels within the subarachnoid space. Um, cool. So what about this one on the right? Then we've kind of ruled out most of the other options. We've only kind of got one left. Now. Um, what thinking in terms of what's going on here? Mhm. Uh, so assume here, actually, the ventricles are normal to assume that they're normal. This is quite an old brain. Um So there's probably quite a bit of cortical atrophy that might make things look bigger than certain spaces look bigger than they would normally. But assume um that the ventricles are normal for the purposes of what else is on there. It's not an extradural. So this is a tricky ct and I put this in deliberately. Um Th this is an example of bilateral subdurals. Um Yes, but what's unusual about this is that we've said that normally with bleeding blood appears bright white. But what we've got here is, is this blood appears darker? Ok. So this has become hypodense, hypodense. Yes. So remember what we've got is we've got a region of, of, of this hemorrhage here. That's, that's hyperdense. So this is hyper dense, which tells you it's much more recent, quite acute. But up here, you've got hypodense. So the oh the hypodense. So it looks, looks darker relative to the brain tissue the shape of it when you combine the two is um, very typical of a subdural. Um But what we've got here is we've got a mix of densities. Um And this here is, is obviously it is bilateral. So that's, that's sort of what's going on when you see it on both sides. But we've got someone who has a history of chronic subdural and has developed an acute. Um, yes. So one is an older bleed. So this one, so it's just to show you that sometimes people can present with subdurals and the initial bleed kind of occurred quite a while ago. Um And so when you look at the CT scan, you might not see bright white, you might see this darker hypodense color but usually fitting the shape of what we'd expect a subdural to look like. Um And this here is just sort of a combination of showing you not just a bilateral subdural, but you've got an acute and chronic subdural evidence of an acute and chronic subdural um in this individual. Um And remember when they go through the CT scan, they're going to lie on the back. So all the fresh blood is going to kind of come down here. Um and the older blood is, is still present um at the top. So that's why you've kind of got these sort of almost like fluid levels. Um So he's got a mix of an old subdural and obviously evidence of a more acute subdural mixing in with um the blood um on this, on this image. And who do we typically see subdural hemorrhages occurring? And what's your kind of typical demographic? Yeah, older patients, older patients and sometimes they don't necessarily need to have had that much of a bump to the head. It could be very minor trauma um by which um they can develop a sub um and, and how might they present? Why might there sometimes be a delay in the sort of being brought to the emergency department? And they're, they're having a CT scan. So sometimes it, they can have a witnessed falls, can't they? Um sometimes the cas um you know, in the elderly, the confusion that can develop as a result of this may be put down to other causes. Um And so sometimes they're not always picked up and that's why when sometimes you do a CT head, you know, on an elderly person who maybe has a, you know, a bit of a longer history of confusion, you may find evidence of an old subdural, in which case, the color of the hemorrhage will be, will be darker. Um So yeah, so, so I think is that older people, um doesn't necessarily have to have had much significant uh injury to the head. Um And we get this characteristic as someone has described banana shape to the hemorrhage. So if you just assume that this was all white or white we've got this banana shape appearance to it. And we contrast that to the the lentiform appearance of an extra drawer. And this brings us in to think about meningeal anatomy and why we get slightly different shapes to intracranial hemorrhage because it's to do with where the bleeding is occurring between the meningioma. Um and also which blood vessels are affected in the bleed, also help to um give context to some of the clinical features or the sort of history as to how people present with these different types of intracranial hemorrhages. Um So with a subdural, does it tend to be an arterial or a venous source? Yeah, it tends to be venous. So that's this, this blood accumulates more slowly relative to a subarachnoid, which will be arterial or an extradural, which will be arterial in most most cases. So that blood is gonna accumulate quite rapidly because it's arterial blood. So you can see how um patients can present quite acutely and can deteriorate quite quickly. Whereas in a subur you're talking about venous blood. So that that blood is gonna accumulate, but it's not gonna accel accumulate as rapidly as uh arterial bleeds. Ok. So let's think about meningeal anatomy. Um So as I said, um we've also got these three layers of meninges which you're all over familiar with. Now, the, the retina, the p um and when we think about are extracranial hemorrhages. So that's our extradural subdural subarachnoid. Um they're bleeding in between different layers of these, of these meninges um in in spaces um between the layers of some of which those spaces are potential spaces. So not spaces that would ordinarily exist unless things are, are filling them. And as I said, the location of the bleed and the blood vessel involved can really help us understand the clinical presentation but also how things appear on radiological investigation. Now, the other thing that's relevant about meningeal anatomy is that although we've got these, these layers around the, the brain that continuous down the spinal cord, and we've got that outer tough layer, the drawer, we know that inside the skull. What's quite um incredible really is that the juror is able to create folds or rigid, rigid partitions uh within particular areas of the brain that help to stabilize the brain to some extent. So it doesn't ruffle around too much. Um But those, those, those rigid partitions, those dual folds can cause particular problems when you've got either a bleed inside the skull or a growing tumor because parts of the brain can start to squish up against those quite rigid folds or squish underneath them, which is when we get a brain herniation. Um and they can also then cause all clinical signs and symptoms to manifest in our patients with, with a head injury, for example, who has an acute intracranial hemorrhage. So if we um go back to our um meningeal layers, and II should draw your attention to this image here. Um So obviously, we've got the scalp. So if this is the very top of your head in the coronal section, um we've got the scalp um and need beneath the scalp. The lowest layer of the scalp is a tissue layer called the periosteum. So remember that your bones um are completely, all your bones are completely shrink wrapped in a transparent, thin tissue there called periosteum. So if you took the humerus, the humerus would have a layer of periosteum on its outside. If you looked at the skull and remember that the skull is made up of more than 22 individual bones that are all then sort of stuck together like a jigsaw. But if you imagine each of those jigsaw pieces, which represents a bone of the skull is completely shrink wrapped in periosteum. So that periosteal ladder there in blue is going to be found on the outside of a skull bone that forms the skull. Um And at the edges of the skull, the bones that form the skull at the edges, the sutures that periostomy is going to be continuous through the edges of the suture lines onto the inside of that skull bone as it faces the brain. So where this blue line of periosteum is, if you imagine that this was the end of, of, of, of a bone that we're looking at one of the bones that forms a skull that periosteum is continuous around the edge of that bone onto the inner surface of that, that bone as it faces intracranial closest to the brain. So if I was to add a, I don't think I can draw on here. Can I a little blue? Um So here I had it in not very well. Um is a continuation of that periosteal as it surrounds the uh the bone here. Um And that periosteal layer when it's on the side of the bone, facing into the brain, that periosteal becomes part and parcel of what we call the Jura. So the jura um is made up of effectively a layer that is stuck to the inside of the skull, which we'll call periosteal jura or the periosteum. Um and a second layer which is called the meningeal drawer. Um And that's the the layer of the JRA that that's facing most inwards, most or closest to the brain. So the juror has um although to the naked eye, for most parts, it looks like a single um where actually it does separate in certain areas to create the folds and to create spaces that we call venous sinuses, which is where all this venous blood that needs to drain out of the brain. So the, the two layers that, that the juror has are the periosteal, which is gonna be this side here, closest to the bone and then a meningeal layer, which is the one that's closest to the brain itself um and is basically up against the Arachnoid, the next layer of our meninges. So we've got the jaw which consists of two layers stuck together. For the most part, we've got our Arachnoid, we've got the subarachnoid space which is full of CSF and our cerebral arterial circulation and the circle of Willis which will be down at the bottom of the, of the brain. And then we've got a peer and the peer is just stuck to the surface of the brain. You can't really peel that off. And so it's kind of a microscopic layer that you, you can't really tease, tease off the, the, the gray matter. Um So the relevance of the draw of having two layers is that um it creates um things to separate that allow us to, to, to get um dual folds. Uh Let me just get rid of my pointy thing. Um And also the these spaces that we call duo venous sinuses. So if I bring you to this, so this is a schematic. So just the black line represents periosteal dura. So that's closest to the, to the bone inside the skull. And then running alongside that in red will be that meningeal dura and for the most parts inside the skull, they are stuck together. Um But then we get this, this separation of the meningeal lay away from our periosteal and that creates a space which is where venous blood will be found. That's a duo sinus. And in some instances, the two meningeal layers continue to stretch down and fuse. And that's what is called a fold. And there's two really important folds, dual folds inside our skull. So here's another image without the brain, um the midline dural fold. So if you imagine this is the folk cerebra as if we were looking at it in a coronal section and now we're looking at the same thing but from the side, uh and the falk cerebra runs right the way from the back to the front in between the two hemispheres. Um And then we have a second year fold, don't we? Which is the tentorium cerebella that runs sort of in a horizontal plane um forming a roof or a tent over the top of the posterior cranial fossa. And so these two folds are quite important because when we have raised intracranial pressure from, let's say, an intracranial hemorrhage, the brain is gonna start to be squished against things. And we've said that the brain can be squished underneath the edges of these, these folds. And depending on which fold, things are being squished underneath, give us an indication of the type of herniation that we might be seeing, but also the clinical signs that might manifest as a result of that. Is that making sense? Uh is the meningio at top of the Arachnoid? Yes. Um I can show you which I do have on here as well. My las point. Uh If I bring in this is a useful 3d image of what we've just described. And mm OK. Can you see AAA sort of section of brain? I'm wiggling around um on your view. Um So this is the the cortex, this is one hemisphere, this is the other hemisphere. Um We've taken this in a section where we're seeing that false cerebra running in the longitudinal fissure between the two hemispheres. Um Here's the most inner layer of our meninges, which is the pier. Then we have the arachnoid layer and then in the space between the arachnoid and the period there uh subarachnoid space. So this is where our cerebral arteries and veins will be and that will be the location of a subarachnoid hemorrhage and then up against the arachnoid, we have the innermost layer of our dura, the meningeal layer and then stuck at this point to the meningeal juror or be the periosteal juror or the periosteum stuck against the, the, the the school board as it were. And we can see in the midline that we're getting separation of the meningeal dura from our periosteal dura to create this triangular space, which is how we get these duo venous sinuses. Um And then these extensions of, of the dura create these folds, these partitions. Uh And the same principle applies as to how that tentorium, cerebella is formed as well. So we've got these rigid um partitions um of which help stabilize the brain but can become problematic when you've got bleeds inside the skull that are gonna cause things to press against or underneath the edges of these these folds. Mm OK. So we talked about the way things look um on a CT scan that makes you think whether it's an extra dural or a subdural. So this, this image here is, is a CT scan um of someone who actually had both a subdural on one side and an extra dural on the other side. So we typically, you know, we may come across extra Ds being described as lemon shaped. So they've got that by uh convex appearance to it and subd been banana shaped or more crescent shaped. And this is to do with where the bleeding is occurring in relation to the to the meningeal layers and the extent of those meningeal layers that allow or dictate how far the blood can spread. So, if we focus on this side, um this is an extradural hemorrhage. So in an extradural hemorrhage, the blood which is represented by this area of hyperdensity is actually between the periosteal dura, which is the back line or the periosteum of the bone and the bone itself. Ok. So an extradural is a subperiosteal bleed on this side of the store inside the skull. Now that periosteum or the periosteal DRRA that would normally let's look at a normal bit of bone. Here, we can see the black line represents the periosteum on that inner surface of, of the occipital bone. Let's say, for example, here that periosteal dr if we follow it round is continuous through the sutures. So around the edges of the bone. So if this, if we look at the periosteum and the occipital bone, this black hatched line goes all the way through the suture is continuous onto the outside of the occipital bone. So that's like kind of shrink wrapping of periosteum around the uh around the bone. Now, this bone here is the temporal bone. So we've got the periosteum of the temporal bone in black highlighted here continuous through the sutures. And if we didn't have this extradural hemorrhage, this black patch line would be here just as it is on the occipital bone. But because the bleeding is subperiosteal, it's lifted both legs of the meninges of the dura off the bone, but the periosteal dura when it reaches the edges of the bone under which it's bleeding. So in this case, the temporal bone, the fact that this periosteum is continuous through the suture. So around the edges of the bone that limits how far the blood can spread. So you get blood accumulating but it's pinched at the edges of the bone under which it's bleeding because that's the boundary of the periosteum relating to the bone. And it's underneath the periosteum that an extradural is occurring contrast that with a subdural because this is going to be a middle meningeal artery more often than not. And that bleeds into the subperiosteal space underneath where that periosteal dura would normally be stuck against the bone in an extradural. Does anyone know what the culprit blood vessel is for an extradural? Sorry, that's subdural, subdural, subdural. What's the culprit? We said it was venous. Does anyone know what this the culprit vein is for subdural? Yeah, it's a bridging vein. Um So when you have a subdural, our bridging veins are running from cerebral veins that are on the surface of the brain. Um and they, they pass through the subretinal space but they, they plumb into duo sinuses, they, they drain into um the wall of a sinus. So they, they, they drain into, into dura effectively. And the typical place for I can show you on my last picture because it does help to have the schematic. Uh this one hasn't got a bridging vein on it, but the the bridging veins run from kind of subarachnoid space and, and plumb in to the wall of a of a sinus, a sinus. And the weakest point is where they actually join the, the sinus. And so when someone has a subdural, what happens is you've got a sharing of the bridging veins and you get bleeding underneath both layers of the drawer. So if I come back to my picture, um here represents the periosteal layer of drawer or the periosteum on the inner table of the skull bones facing the brain, the red represents the meningeal layer. I just assume that they're really stuck together. At this point. I've tried to draw them as close together as my hand would allow. Um And so the bleeding is, is, is between the meningeal layer dura and the arachnoid. So that's why it's subdural. It's, it's underneath both layers of dura and that blood then can the full extent of the surface of the cerebral hemisphere. And it's only limited where the meningeal lara folds in to form the false cerebra. Hence, your subdurals won't pass the midline, they won't cross over to the other half because they're prevented by the folds of JRA coming in at the, the dural folds. So your shape, whether it's an a lemon or a banana is to do with whether the bleeding is occurring between the bone and the drawer. And that being the periosteal drawer specifically, or it's occurring entirely beneath all layers of the drawer. So that's underneath periosteal and the meningeal drawer. So between the dura and the Arachnoid and that's your subdural space. And that blood can track the entire curvature of the surface of the brain, which is why you get that b banana shape, um appearance but limited by the folds, the dural folds as they come down into the midline. Oh, it hasn't caused more confusion. Um But your appearance is, is to do with the bleeding between the different layers of, of, of the meninges ok, few more minutes. And I'm happy to, to carry on for another sort of 5 to 10, but people may need to get, get away for eight. But I just thought I'd add in um, another neurological sign that, that, that develops in this, you know, it could be in this gentleman, but anyone that's, that, that's got an intracranial hemorrhage. Um So what, what, what we're seeing here. So I assume that this is our original patient that's got a head injury. You've seen a CT scan, you're doing constant neuro observations and now this sinus developed. So what do you see and how can you link what might be going on intracranial with what's now present as a clinical sign in this image? Again, if you want to share any thoughts on the chat just in your own head, we've got anisochoria um and an isochor often pronounce it isochor. So unequal pupils lovely. Um And the fact that we're examining with ap toch, we'd expect the pupils to be constricted and we can see on this side that we've got a dilated pupil and it's fixed and dilated. Um So what, what might that suggest in the context of a head injury? Why might we have a fixed dilated pupil? What might be going on? Ok. Or cranial nerve has now become involved? Excellent. Yeah, Jenny. So we've got, we've got involvement of the third nerve. Um So we've only got it parasympathetic functions involved at this point, obviously, if you had a full sort of compression of the third nerve, we'd expect tors in the down and out. But at the moment, all we're seeing is evidence of those the parasympathetic functions being compromised. And this has occurred because if we come back again to, to um dual anatomy, uh we talked about uh these folds. So this is a coronal section through the brain. Here's our falk cerebri in section. This will be your superior sagittal sinus er insection. Um and these are the tenor er cerebella er dural folds. So that's, that's in section as well. And what can happen is as you increase um pressure inside, you can see that different parts of the brain can be herniated underneath the folks or even down and through the tentorium. And these are all types of brain herniation, which are all really bad, aren't they? Um Does anyone know what this type of herniation is? The the one that is uh underneath the Falk cerebra? And what the type of herniation is that goes over the edge of the tentorium. And then the third type of herniation is when the um brain stem is forced through the foramen magnum. Yeah. So this one got subfalcine, that will be this one. So subfalcine means underneath the folks sub means under. So subfalcine herniation uh that's often the one that when we look on CT scan, we see the deviated, we see that that we saw in that first uh ct of the extradural uh that can indicate subfalcine herniation, especially if your ventricles are squished as well. Um transtentorial or uncle uncle herniation is when the temporal lobe squeezes over the edge of the tentorium. And it's usually the uncus, which is a named part of the, of the temporal lobe. And it's here that the the third nerve can be squished. The third nerve runs in really close proximity to the edge of the tentorium. Uh so it can be compressed in a uncle herniation. And then the third one as an example on this image is is a tonsillar herniation. So in a sub falcine, we've got what's called the cingulate gyrus being squished underneath. And the anterior cerebral artery is particularly vulnerable to being squished in a subfalcine herniation. Then that's going to cause issues with ischemia in the territory of what the cerebral anterior cerebral artery represents. All you know, neurological um sequela as a result of effectively ischemia from the anterior cerebral artery could occur in a subfalcine herniation, transtentorial. We said third nerve lesion can usually be an indicator that someone is having a an uncle herniation. But also you can press into the proximal part of the brainstem, which is the midbrain where you've got all these motor tracks running and very dense packed together, so they can be squished. So you may get motor signs manifesting if you've got compression of the, the cerebral peduncles or the part of the midbrain where those mortar tracks are running. And then lastly, which is, um, you know, sort of, yes, sort of end game really when it comes to, to sort of herniation when someone's corning and pressure is so great that effectively the brain has been squashed through the frame and magnum. So your brain stem is being compressed as it squids through uh alongside the, the, the bits of the cerebellum called the tonsils. That's where the tonsil herniation comes from. So you're squishing so much through a narrow hole, the frame and magnum that things are going to get squashed. And there's lots of really important functions in your brain stem like cardio respiratory functions. So patients become very unwell very quickly and it's usually usually terminal, please. Uh There's just a few pictures there. Um I'm happy to kind of just wrap things up there. Um Just to see that we've got to eight o'clock and I've kind of reached the point to where I was hoping to, to kind of get, get to just in relation to looking at meningeal anatomy and intracranial hemorrhages, how that looks on CT imaging and using some of the meningeal anatomy um to, to understand um you know how they appear on CT imaging, but also clinically how they present and what some of the clinic clinical sequelae might be as a result of that. Um If people wanted to obviously get on and do other things and conscious of the time. Um or if people want to hang on, I'm very happy to send just the last sort of five minutes um on um bringing in just another neurological um sequela uh or, or uh um manifestation that this particular patient presents with uh in this case. Um But I'm happy to be led by, by what, what people would, would prefer or want to do. So if you want to stay, um you can just stay the um And if you want to head, then just say bye in the chat and, and feel free to, to exit. Uh but just to summarize just when we're looking at intracranial hemorrhage, extraaxial hemorrhages think subarachnoid, extradural subdural hemorrhage always appears as white on a CT and a CT non contrast. CT head is entirely appropriate if you're determining if someone's got an extra axial hemorrhage. Um the appearances of those hemorrhages, you can describe by knowing between which layers of the meninges those bleeds have occurred. And some of the clinical manifestations of how people present with extra axial hemorrhages can be determined by, is it an arterial bleed? Is it a venous bleed? Is it causing irritation of the Arachnoid and the p as we see with the subarachnoid causing meninges and signs which we wouldn't normally see with an extradural or necessarily a subdural. Um and herniation again, that links to meningeal anatomy got these dural folds and we can get herniation syndromes that occur when parts of the brain are being pushed up against or underneath. We've talked about the sub sign of 10 tentorial sorry, uh herniation and a corning um or tonsil herniation and some of the furthest sequela that, that may manifest in patients that are developing herniation as a result of mass effect of intracranial hemorrhage. Um Yeah, so that's, that is in a nutshell. Uh Some of you want to stay, which is lovely. Um So I'm just going to carry on talking. Um So stay if you want to hear and uh please head off if you want to head off and thank you very much for, for joining me on the, on an evening right back to the case then. Um So, so how would you manage? How would you manage? Now, you've got your CT head, you've got someone who's presented with a typical history of an extra jaw, your CT head has confirmed it. You've now got a third nerve lesion which um along with the CT findings might suggest that you're starting to herniate. So what are you going to do? What does this chap need? Um You send him home with some paracetamol? Excellent. Yeah, he, he needs a neurosurgery, doesn't he? Um So um he's going to need it pretty rapidly pretty quickly. Um So they're probably gonna want to open up the skull and evacuate the hemorrhage. Um And that relieves the pressure, doesn't it? On the, on the uh on the brain and, and people can make a pretty good recovery uh providing this is recognized and treated um quickly. Um Anyway, so he, he has this craniotomy. Um and he, he, he um take him back to the ward. Um and on the ward round, um he's, he's reexamined. Um and um there, there's some suggestion of, of some problems with his left upper limb. Um What, what, what, what do we think could have explained involvement and cause of his or his neurological signs as they are currently described? So, have we, we've got um motor motor signs in the left upper limb and assume it's involving the whole limb. Um So we've got a suggestion, could it be uh ischemia in the area of the anterior cerebral artery? So it's certainly something to consider about consider given that um the there was some evidence on the CT scan of a subfalcine herniation uh with the, the, the midline shift that we saw on his original CT scan. Um So there could be some ischemia. That's something to, to, to, to consider. Um whether when we think about anterior cerebral artery and think about the territories of the regions of the brain supplied by the anterior cebral artery, does that link with parts of the brain that are responsible for arm? Yeah, or is the anterior cerebral artery, does its territory more correlate to parts of the brain that are involved in perhaps another part of the body's motor function. So we've got a primary motor cortex. So um a absolutely could be. So if we bring up appearance of the brain. So here we've got the brain looking from the left side. So this is the left hemisphere and this is the right hemisphere. Um And obviously, we've nicely separated this into colored lobes. Um But if we were to look back at his, his, his examination findings, so he's got motor signs. Now, are these motor signs, upper motor neuron or lower motor neuron signs and put in the chat? What you think, footle or lower motor neuron signs affecting the left upper limb? Ok. Good. So we've got upper motor neuron. Good. So, so hopefully, you know, as you're sort of getting through phase two, you should be reasonably confident with upper versus lower motor neuron signs and how they manifest when you examine someone clinically. So the presence of reduced power, hyporeflexia, increased tone, all suggest um involvement of the motor pathways, particularly the upper motoneuron part of that pathway. So that's the pathways that join the motor cortex, run through the brain, the brain stem run through the spinal cord and then synapse on two. What will be the low motor neuron? So the presence of, of, of the hyperreflexia, hypertonia, tell you we're talking about involvement of that upper motoneuron part of that pathway. Um So we'll mention then, OK, well, prime multi text. Um So if we come back to our two pictures here. Um I remind you that his, let me just quickly show you the CT scan. Which side did we say? So the CT scan, was that OK? It's just a man that's where his bleed was and postoperative leg, he's now got leftsided. Mm or motor neuroscience. So on the image here, bye bye. The brain. Where do we think the uh problema which is of indicate a region on the brain? Now again, obviously, you can't interact live. I can't see what you're pointing at, at home. If you want to make a point on your screen to where you think it might be. So you've got to tell me which side of the brain and, and, and, and, and where in relation to these different colors uh and the various gyri sul that we can see on the surface. Oh So hopefully, um we've said that we've got mortar signs. So we're thinking given the context that this is someone that's had an extradural hemorrhage that's been pushing onto the outside of the brain. We're thinking what's on the outside of the brain that could be responsible for motor function that could have been compromised from the pressure of, of this extradural hemorrhage. Um So we've got the side which is correct. It's got to be right. So, remember if we were talking about involvement of um the motor cortex. So the very surface of the brain in relation to motor function that will manifest with motor signs on the opposite side of the body, won't it? In terms of open motor neuro signs in phase of the arm or the leg? So, we've got a few people saying it's the right, which will be correct. Uh, it fits with the side in which the extradural hemorrhage was. Um, it fits with the fact that he's got contralateral, left sided motor signs in the upper limb. So we are looking at the er right half of the branch down here. Um And I've seen a few of you talk about precentral gyrus as being the region where the motor function is represented on the cortex. And that would be entirely correct. So it's along this bump here. Um So this would be the central sulcus that delineates the frontal lobe from the parietal lobe and right at the back of the frontal lobe, we have um a large part of that, that the Gyrus sort of representing um conscious control, motor function, voluntary motor function. Um And where in relation to the extent of this, this Gyrus is the arm represented and the face represented and the leg represented um what, what, what sort of, where have we got of remembering how things are topographically represented across this Gyrus. Do you remember the homunculus little man? So, right down here, towards the, the, the sort of most lateral portion of the homunculus, the most lateral portion of our um precentral gyrus, we'd expect the muscles of the face to be represented. So one half of the face, then we'd expect um arm to be represented here and trunk. And then most media would be like and, and that sort of dips down into the longitudinal fissure um a little bit onto the surface of the cortex, we just can't see here. And, and if you think back to your territories in terms of anterior cerebral artery circulation, um this sort of rim of the hemisphere is, is, is is supplied by the anterior cerebral artery and very much the kind of medial surface of this hemisphere that you can't see. It's kind of the opposite side of, of looking at this. So the medial side of the hemisphere is very much supplied by the anterior artery. And this is a very um small sort of region of the frontal lobe and the parietal lobe. And so, if it were an anterior cerebral artery that was being compressed from the sub fell herniation, we'd expect to see some leg signs. Um And we'll assume that in the information I've given you that the leg is fine. Um We're just seeing arm signs. And so we could infer that maybe that extracranial extradural hemorrhage was pushing up against this region of the brain and it's caused some compression. Um you know, some compression ischemia of of the part of the cortex that's responsible for voluntary motor control of the arm because that's what this bit of the brain is responsible for? Um And why does that manifest in the opposite side of the body? Because this will be my last question. If we've got involvement of the right motor cortex, why does that, you know, even if it was any part of the the the primary motor cortex, whether it was the arm, the leg or the face, those motor deficits would manifest in the opposite side of the body. So why, why is that one more picture is just the mon, so it just shows you that idea of the representation of the face, arms, hands, trunk leg. Much more media. Yes, wonderful. We all remember uh lots of Decca uh when it comes to tracts in neuroanatomy. Um and our motor tracks er indeed do dec uh can I remember where at what point the motor tracks dec the upper motor neurons. What point do they cross over? For the most part? 90% of them? Um Where do they cross at what level in the central nervous system? The the wonderful. Thank you, Irene. Um So this again just a very basic schematic. We're looking from the right uh right hemisphere, left hemisphere is uh what represents a single upper motor neuron in purple. Um Let's say it's taking information from the part of the motor cortex responsible for the arm. Here we are in the right primary motor cortex. This neuron runs all the way down through the internal capsule through the cerebral peduncles of the midbrain, right the way down and they devastate, don't they at the bottom of the mid the brainstem and the medulla? So the um medullary pyramids, that's the shape of the brainstem. And we see all those tracks crossing over and hence why, one half of the brain from a motor function controls the opposite part of our body. Um So that would then communicate onto spinal nerves that go on to supply the, the nerves that um in the muscles of the upper limb. So that was all I was gonna add on that last bit of the case is to bring in a bit of cortical anatomy. Um and uh open motor neuron, motor tracks. Remember that they cross um any questions on that then um before kind of wrapping, wrapping things up, I wanna stop sharing, I think never stopped shattering. Yes. The thank you very much for that and thank you so much to everyone that's stuck around as well. 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Um So, and if you do have any questions, doctor has kindly stuck around, so feel free to ask. OK, questions. I've got a question, I'll stop the recording that. So the the upper motor neuron signs could very much have started preoperatively. I just decided not to mention them at that point. Uh So, um yeah, they, they could very as they have been present from the start. Um But I just thought I'd introduce those, those clinical features um as a sort of separate way to, to looking at the cortical neuroanatomy.