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Hi, everyone. Uh, welcome to the, er, fifth and final session of mind the Bleeps toy series. Um, today we have a note who's an I MT from Barnett Hospital. Um, he'll be discussing the cranial nerve exam. Um, after he's discussed the exam, we'll move everyone into breakout rooms, er, like the previous weeks. Um, and we've got four facilitators today um to help with the breakout rooms. Um, so you can discuss each case um with them, um, when we move into breakout rooms at roughly 730 when a nouche is finished. Um, but to kick things off, I'll hand you over to ache to walk you through the, the cranial nerve exam. So, um, over to you, ano nice to meet you everyone. Um, so you, you'll get access to these slides. I'm gonna try and rattle through as much of this as I possibly can in a, in, in 25 minutes. But the cranial nerve exam is probably one of the most useful parts of the neuro exam. So there's lots and lots of pathology. We'll focus on the aspects of the order of which to do things in that, the pathology and things you can look at in your own time. II won't spend too long dwelling on that. You might want to discuss this in your smaller groups in a minute, er in, in around half an hour as well. So aims of this talk, I had to examine the cranial nerves in a structured fashion, er structured fashion, understanding the role of each part of this examination and how it helps your like neurological diagnostic process, relating the examination findings to common pathology and differential diagnoses for those and to produce a realistic basic investigation strategy based on what you've found. Th this is the exam in, in a nutshell. So introducing yourself, examining the upper cranial nerves, the lower cranial nerves and then summarizing and presenting the examination and depending on which medical school you go to and where you are in the country. And how long do you have an oy, often the cranial nerve exam might just be split into upper or, or and lower. Some place may split it into eye related cranial nerves and non eye related cranial nerves. It really depends. So this is something that they could actually do. The introduction doesn't change. It's the same as with any other examination, introduce yourself, confirm patient details, consent them appropriately. What are you gonna do? Uh is it OK if you go ahead and examine them? And uh I was always taught to ask these two questions. Are you in any pain at the moment. And are you comfortable starting off with observation? I like to split things out, er, split things into things around the bed for a cranial nerve exam. So, could be n I'm signs if, if you were worried about a patient with swallow issues, are they wearing glasses or have they got glasses all on the side? Cos you ideally do want them to be wearing them, do they have any hearing aids? If they're not in their ears, you might wanna put them in. Otherwise, it might be a bit tricky to examine and dentures are a useful thing to note because these can affect how people speak, looking at the patient itself. Most important things are the most important thing is basically just asymmetry. Is there anything asymmetrical about their standard posture? Uh and then you can look at these other things as well. So going in order of the cranial nerve, so cranial nerve one is the olfactory nerve in the context of an AK have you noticed any change in your taste or smell will cover the olfactory nerve. If you want to do a comprehensive assessment, then like you can test using scents and these smelling salts. Um But that's very much beyond the scope of an osk. Uh cranial nerve two is incredibly, I so cranial nerve one is a simple question, but cranial nerve two is very important. So the optic nerve provides a special sense of vision. The part of this examination are split into a lot of different things. Um I like to do visual field assessments first because I think that that's the most time consuming thing and it can often point to lots of specific pathologies. So this is where you're covering the same eye as the patient. And ideally using a red pin, you're gonna slowly move into the field of vision. The important you'll switch over when you're doing the other eye. And the key examination technique part for this is trying to use a redheaded pen, it improves sensitivity significantly, make sure you go slowly um and you ensure that the patient is looking directly at your nose. They don't look to the side to have a look at where the pin is as that can give you a falsely enlarged visual field. The other important thing is to make sure that the pen or whatever object you're using is he held equidistant between you and the patient. So you're assessing like for like now, if you happen to have some kind of visual field that you affect yourself, this might not be a good test and it might be better to just send the patient for formal visual field testing. So that's what I like to start off with. We'll talk about some of the pathologies you may see there visual acuity is using a Snellen chart. I'll show you a picture for one of those, you'll definitely have seen one of those, especially if you wear glasses yourself. Um in the UK, we, we scored the Snellen chart based on there's numbers alongside based on how far they can read. So you might have heard of 2020 vision that's in feet. We use um 66 in the UK because we use metric system moving on from there, looking offered to use er Ishihara plates to test for any deficit in color fundoscopy is relevant if they've come in with any visual complaint. Now, in the endoscopy, you might not be expected to perform fundoscopy in the context of a cranial nerve exam. But in real life, it is important to perform this. So I II would at least offer to to your examiner. It would be like I'd like to check the back of their fundi and then there's a few reflexes that we'll talk about in just a moment. So uh just briefly specialist equipment. So left is uh the Snell and chart for visual acuity. So you wanna do one eye at the time and you want to optimize your patient's vision. So if they wear contact lenses or glasses, you want them to have them on when, when you do this test, unless of course, you're you're trying to see what level of correction they'll need. But usually you just refer to an optician for those kinds of things. The middle isn't an issue horror plate. So if any of you are color blind, you won't be able to see the number in the middle. If you can see a number in the middle, you, you're not color blind, there's various types of color blindness. So th this is testing red green. Um, I it's appropriate to go through all the different sets of plates in order to make sure you've excluded all types of color blindness. Again, you won't really, it's important to mention this to your examiner, but it's quite time consuming. So you might, you wouldn't be expected to do all of this in an osk usually. And then uh number three is uh what we were talking about with visual field testing. So covering the same eye and using a red pin and notice how there's sat like knees to knees with the pin roughly in the center between both the examiner and the patient. So to talk about some pathologies to expect here. So I'm, I'm I'm not gonna talk about any ni pathologies today. So I'm gonna talk about largely common things that come up in er undergraduate osk. So if you think if you see a bitemporal hemianopia, so loss of the lateral visual field of each eye, you wanna be thinking of a a pituitary mass or something pressing on the optic chiasm if you're losing the same visual field in both eyes. So the the right side of both eyes or the left side of both eyes, this is called a homonymous hemianopia. Sometimes this might start as just a quadrant. So just the top left on both sides or the bottom, right on both sides before progressing to a full hemi visual field loss. If you, if you see this, II, you want to think of something behind the er optic chiasm. So think about something like a stroke, uh an occipital or a um or like an MCA in a due to optic radiations can cause some things like that. And then if you're, if you've got just visual symptoms in one eye, you want to be thinking about lesions in front of the optic eyes. And so either the optic nerve or the retina itself, if you've got monocular changes in vision, then fundoscopy becomes extremely important as it i it's likely it's very likely to be a retinal pathology if not an optic nerve pathology. So when you're assessing pupil reflexes, II like to do these now as well. So the direct reflex, the consensual reflex accommodation and then looking at the swinging light reflex for an R APD, which is something we'll touch on in just a moment. So the the the the principle of reflexes is when you, you shine a light, a bright light on one eye, both eyes should constrict because the right eye should have a direct reflex where sensing a load of light hitting the back of the retina that will basically cause via various pathways. The signal is received by the optic nerve and you'll get a direct reflex causing the right eyes, pupil to construct while this is going on, you should also see constriction of the left eye even though you're not shining a light light on the left eye. Because after passing through the optic nerve, the signal passes through what's something called the Edinger Westphal nucleus, you don't need to know detailed neuroanatomy for for for the session. Just know that this nucleus exists and basically this will reroute the signal to the other eye and cause the pupil to constrict on that side. A any the loss of a direct reflex suggests an optic nerve pathology. It's not super specific. It's something we need to do as part of our examination. Now, relative afferent pupillary defect is something that is clinically incredibly useful. So this is where your swinging light test comes into it. So you rapidly swing the eye, er the light from right eye to left eye back to right eye. And you are going to pay attention to what each of the pupils is doing in the context of a pathological eye. Ie one with a relative afferent pupillary defect. When the light is above the pathological eye, initially, it will constrict, you swing it away to the other eye, the consensual reflex kicks in and it still is constricting. So, and then when you move back to the pathological eye, because it's got a relatively lower level of signal being transmitted through the optic nerve, it will dilate. So, even if it is initially constricting. So let's say the right eye has a relevant a relative afferent pupillary defect. Initially, when you shine a bright light onto it, it's direct reflex is intact. So you will get constriction, then you will shine it onto the left eye, which is also normal. So you will have a normal consensual reflex. So the right eye will stay constricted. But then when you move back to the right eye, because the signal in the right eye is less than it is in the left eye. Because of some pathology, usually in the optic nerve, the right eye will slightly dilate cos it is relatively less sensitive than the left eye. Um That's probably what I'm not gonna go over it again. But when we're in breakout rooms, we can talk about it because this l localizes the lesion to the optic nerve on one of the sides, which is very useful. And that means it's, it limits the diagnosis to a number of different pathologies moving on from cranial nerve to grouping 34 and six together. Into what I would just describe as the eye movement, cranial nerves. The way to assess this is you get the patient to fix it on your finger and um follow in an H. So you're testing the extremities of up gaze down gays left and right. It's important that you ask about pain or double vision. When you're examining this part of uh when these, we are examining these cranial nerves, um just a technique thing. So as at this point, lots of people look for things like nystagmus, which is a sign of cerebellar disease. Try not to move beyond 30 degrees from the midline. Cos beyond this point, a lot of people will generally have some physiological nystagmus which makes the sign difficult to interpret. It's not really, I wouldn't worry too much about that in the context of your like acies. But in real life, it's a useful thing to know when nystagmus is um pathological or physiological. These are what each of these nerves do. So they innervate any of the various muscles that control movements of the eye. And based on lesions of these nerves, you'll get various ophthalmoplegia which are illustrated on this slide. Um I'd probably just this is a, this is looking at right sided palsies of the 3rd, 4th and 6th cranial nerves. The most um the classical one that is like an exam favorite is generally a oculomotor palsy. So a cranial nerve, three palsy where you get uh at rest a down and out pupil and ptosis of the affected eye. So if you look at the middle image, the look at right third nerve palsy looking straight is what I would look at. And that's like a classic exam scenario. Um There's some other things to consider if you notice like ophthalmoplegia. So if you see an isolated abducent nerve, so cranial nerve six palsy. So that's a failure to, to add up the eye on the side of the lesion. So move away from the midline. It's important to consider raised intracranial pressure as a differential, especially if it's a bilateral absence, nerve palsy. This is the longest intracranial root out of any nerve. So it, it's the first nerve to get affected in the context of raised intracranial pressure. If you see that you might want to consider something like a CT head to rule out space occupying lesion. The other interesting thing that you might have read about in textbooks uh or when you've done your knee replacements is surgical versus medical third nerve palsies. So very briefly, I I've got a diagram on the next slide which um illustrates us a bit better. The cranial nerve three has the motor fibers that um are responsible for eye movements running through the middle, but around the outside. It also has s pupillary fibers that are given off by the sympathetic trunk. Basically. Um when you lose a vascu the vascular supply of cranial nerve three, there is ischemia going outwards because the vessel runs through the middle of the nerve. This means that the sympathetic fibers around the outside are preserved. So if you've got a medical third nerve palsy, whereby there is vascular disease of the supply of the optic nerve, only, the inner motor fibers of the nerve are affected, the sympathetic fibers that just happen to go around the outside are completely unaffected. So you will have a normal pupil. Now, when you've got a surgical third nerve palsy eye, you've got some kind of, the classic exam thing is a posterior communicating artery aneurysm or it could be a tumor compressing on the optic nerve. You will lose both the, you will lose the sympathetic fibers as well as the motor fibers. So you'll get a dilated pupil. And ultimately, all you need to know is if you see a third nerve palsy with a dilated pupil, you should probably do some a CT angio to look for an aneurysm before moving forward because there's probably something compressing the third n. But that's what the takeaway is ID. I think it's probably slightly beyond the scope, but they do seem to tea. I was taught about it when I was in medical school, which is why II put it in this talk. Anyway. Um The last movement issue that's uh I'm briefly gonna touch on is something known as a internuclear ophthalmoplegia or an in o. So this is where based on the side of the lesion, you'll be unable to add up to the eye. So if you've got a left, so this pathway is the, the medial longitudinal fasciculus is the pathway that connects the movement mo muscles of your right eye to the movement muscles of your left eye. So this is because different muscles are responsible for adopting and abducting on either side, just think of this as the pathway that allows you to coordinate all of your eye movements. An internuclear ophthalmoplegia basically refers to a failure of coordination of these eye movements. A good example is here on the left. So we've got a left sided M LF lesion. So this means the left eye will fail to adduct. And as the left eye fails to adduct, the right eye will have some nystagmus. So you're looking for in a single direction, you're looking for a failure of one eye to adduct and the other eye to flick and have fast phases of correction as it has nystagmus. If you see the sign, this means that there is a very specific lesion in this one tract and this is quite speci it's not wholly specific, but it suggests that there's demyelination. So you should think about er multiple sclerosis. It, you can have this in both eyes. So for example, if you have a right sided in o the right eye will, will fail to adduct and the left eye will nystagmus and you can have both happen at the same time. But regardless if you see this finding a multiple sclerosis should be high on your list. So that's it for eyes moving on past the cranial nerves that supply the eyes, you've got the trigeminal nerve. So this is a basic sensory examination in all the modalities. So, pain and temperature, soft touch and you can do vibration, we generally keep it to those two. But if, if they'll give you a tendon hammer, uh a tendon, a tuning fork, you can do vibration again. Um This is uh there are three branches. So the ophthalmic branch, the maxillary branch that supplies this part of the face and the, the mandibular branch, there's, you want to check both sides and you want to compare like for like for every single time, the motor supply of the trigeminal nerve goes to the muscles of mastication. So there's things that allow you to chew on your food. So check for the strength of mao to muscles, check for temporalis and the pterygoid here. So jaw opening, jaw closing, well clenched, just check all the muscles and make sure that they're tensing appropriately. Uh The jaw jerk is has kind of dual innovation from the cranial ne five and seven. So I would offer this. So this is where you keep, get them to open their mouth, like partially open the mouth, put a hand on there and tap with a tendon hammer. If you see like the jaw do some uh just move jerkily, that's the jaw jerk. If it's present, that's a pathological reflex. Cranial nerve seven is the facial nerve, which is probably the uh after the eye nerves, probably the next most common exam culprit. So this supplies the muscles of facial expression. It also provides taste to the anterior two thirds of the tongue via the corrida tympani and it also provides the nerves to the stapedius that dampens down loud noises. The reason they love testing the facial nerve is, is a common mimic for a facial group. So you can have a lower motor neuron, seventh palsy, which has various, which has various causes. Um that is an important differential for stroke. Now, the important distinguishing fact. So how do, how do we go about examining the cranial, er the facial nerve? So useful things, raise the eyebrows, shut your eyes and stop me from opening them. Go use t two hands for each eye because it's very difficult to open an eye even if it is weak by using just one hand. So use two for each. Uh first is your lips, stop me opening your mouth, puff out your cheeks. Um I once did an OSC where this was like the only sign they had and you could just see that they could like, it was just very obvious as soon as you got them to do this, that one of the sides that just couldn't do it very well. And then lastly, the corneal reflex uh can be lost as part of the facial nerve as well. So that's where you tap some cotton onto the cornea and see if they blink again. That's something to offer rather than something to actually perform co in an oa patient can't have it. 12 students in a row test corneal reflex. It's just not very nice. So those are the things you wanna test for. And this is the key here. So is it a peripheral facial nerve palsy or have, has the patient had a stroke? And the key here is forehead sparing uh and orbicularis oculi. So, eye closing, muscle sparing, these muscles have dual innervation. So if you have an upper motor neurone lesion, they will have some supply from the other side. So the forehead and orbicularis oculi, the muscle that allows you to close your eyes tight will both be spared because there will be some innervation from the other side of the cerebral hemisphere. If you've got a lower motor neuron lesion, this is after both hemispheres have converged. So you will lose both of those muscle movements. But this this is a very, very important distinguishing factor. So if you, if you see forehead muscle impairment, then think it's a lower motor neuron lesion. If you've got preserved forehead muscle, then think it's an upper motor neurone lesion. And you should be thinking about stroke. Hello, how are we doing for time and fine, we should be done in the next five minutes. Um Cranial nerve eight is the vestibular cochlear nerve, which has two functions as per its name the cochlear testing. You can do some rough testing by just ruffling some your fingers or a tissue in each ear and asking them which one is louder when you, when they close their eyes a better version of this is doing Webbers and rings tests, which we'll talk about in a moment. Vestibular testing really is beyond the scope of a cranial nerve exam because it takes AAA bit of time in itself. Um If any, any of you are interested, you can Google the hints examined that is quite useful in terms of vestibular testing. So we is so Rin's test is you ping it, you ping a um tuning fork, you put it on the mastoid er process here. When they stop hear, stop feeling it, you then stick it in front of the air in a in a person with normal hearing air conduction, their hearing through air should be better than their hearing through bone. So they should still be able to hear it. Weber's test is where you ping the tuning fork and you put it in the middle of their forehead and it will lateralize to one of the ears. If there is some kind of hearing loss, you need to combine these two tests in order to figure out whether a patient has sensory neural or conductive hearing loss and to figure out which is the affected a air. So if we're talking about sensory neural hearing loss, so this is the fibers within the air or there's damage to the nerve itself, air should remain air, air conduction should remain better than bone conduction. Uh and the Webers test should be louder in the normal air that isn't affected by sensory neural hearing loss in a conductive issue. So this is the common cause of hearing loss where you've got lots of air wax, bone conduction will be better than air conduction, cos the canal will be blocked, but bone conduction will will will therefore be longer than air conduction. And Weber's test will be louder on the side of the affected air. Again, this is a useful image to look at and to think about the last few nerves have slightly, uh everyone has their own ways of testing them. So, cranial nerves nine and 10 are the glossopharyngeal and the vagus nerve. So the functions split but it's easier to test them together. So cranial nerve nine does taste for the posterior third of the tongue supplies from the pharyngeal muscles and is the afferent branch of the gag reflex. So, feeling that you're gagging, the vagus nerve does the efferent gag reflex ie producing the muscular movements involved in gagging, uh and is involved in a lot of the muscles producing speech in the mouth, knowing those things. Some basic tests we can do as part of the screening tests that we'll do as part of our cranial nerve exams is inspecting the soft palate and uvula, especially when the patient is saying something like, ah and it's just seeing how it's moving, it should be symmetrical. Any asymmetry suggests a a cranial nerve 10 lesion if producing a strong cough is part of cranial nerve 10 as well. See if they can swallow some liquid. Uh, so do a dry swallow first and then you can try some solids and then you can try some liquids if there's a cough after a swallow, or there's a change in their voice that suggests that there is an ineffective and unsafe swallow. And then gag reflex is something they'll offer. But again, you know, oy, you're gonna be like the 10th person examining. You do not want that. They will not find someone that is happy to have the gag reflex tested that many times. Yeah. So kind of both. All of these tests will test some glossopharyngeal and some vagus nerve function. It's very difficult to specifically test either or the last two nerves are very easy to test. So the spinal accessory nerve is in er, involved in shoulder shrugging. So check strength of the patient shrugging their shoulders, ideally do one at a time. But in the interest of time, it's reasonable to do both sides at the same time. And the hypoglossal nerve is responsible for tongue movements. So tongue movements will deviate to the side of the lesion. So if you've got a right sided hypoglossal nerve, you will have weakness on the right side. A uh extension of the tongue on the right hand side. So the tongue will move to the right. Wait, no, I said that wrong. If you have a right sided hypoglossal nerve lesion you won't be able to extend the tongue on the right hand side. So the left side will extend further. So the tongue will d will deviate to the right. Once you've finished examining you, you've got a few options. When summarizing, you can go through all the cranial nerves and say what's normal, what's abnormal or you can summarize the syndrome if you've identified one. So for example, this is a 73 year old gentleman presented with an isolated left cranial nerve, uh third cranial nerve palsy as exhibited by a down and out pupil and ptosis. All other cranial nerves are normal. So it really depends on how confident you're feeling after your examination. If you think you've localized the lesion and you've figured out what syndrome the patient has, you can just present it like that. If you're unsure, no one is gonna penalize you for going through the cranial nerves. Things to complete your examination by doing include a full neurological assessment of both the upper and the lower limbs and imaging is an important thing to consider. So, if you're worried about some acute onset and you're worried that this could be stroke, do act. If it's not, then I MRI is the gold standard for visualizing what's going on. If you've got an isolated cranial nerve palsy, just think about causes of a mononeuropathy. So this is my last slide. But uh I've got a list of causes on my last slide when when we get to it, question questions you might be asked with regards to this include give a differential diagnosis or localize the lesion. So they're just asking you. So if it's a cranial nerve palsy, which cranial nerve is involved, it will suffice and then what could be the causes of that cranial nerve being damaged? If you have certain visual field impairments, you might have to give further localization of the lesion. So again, bitemporal hemianopia behind the chiasm. Uh no, at the chiasm, homonymous hemianopia behind the chasm. So it depends on the pathology. But as with any neuro exam, it's all about localizing the lesion with. So common exam topics are often strokes presenting with visual symptoms, some kind of mononeuropathy. I would focus on those two things as the main kind of things that come up in your er acies. And they might ask you about those further investigations we chatted about if they ask you for courses of a mononeuropathy. These are a list that you can always almost always use, but that I think that completes my presentation if we wanna do breakout room. Sorry, I'm running four minutes behind schedule. Great. Thanks, Anish, no worries. Um That was a really good run through. Um And really good kind of discussion around the, the pathologies, the, the pathophysiology of the um um the nerves as well. Um So we'll move into the breakout rooms with the tutors um because there's not many people in the call. What I've done is in room one for the first case, if we have Doctor Lander, um, facilitating that discussion and then the second case can be Doctor Moosa. Um, and then for room two the same. So, er, first case, Doctor Bellamy and second case, Doctor Ward. Um, but yeah, we'll try to, um, stick to like 20 minutes to go through the cases. Um, so if we aim to get back just before, just before eight, that would be great. Um So if you just go into the breakout sessions on the left left hand side, um, click on the tab and go into your room number. Um, and let me know if you've got any issues, um, with accessing the breakout rooms, but it should be ok. Um Just let me know, um, I'll post the feedback form in as well. Um, so there we go a after you come back. Um, if you could provide the feedback, then you'll get the, um, attendance certificate for the teaching. Um Yeah. Right. Um, I'll see you guys just before eight o'clock. Enjoy your discussions.