Radiculopathy

[Music] Med conversations. Hello and welcome back to another episode of Med Conversations. This is a partially e-podcast but the more important landmark thing about this podcast is that we've just got a bunch of new recording gear. We listened to what the people were saying and so hopefully we sound crystal clear like you're standing right in front of us on a pompous ward round. It was a good devil here. And back is here too. And today as a special treat for Rahul he's been begging me, begging me for years to do this podcast. So here we are. We're going to talk about one of the best parts of the nervous system. It's hard to choose but one of the best parts of the never is. That's what we'll be talking about today. So we'll start off with some anatomy which is terribly done over a podcast but we're going to persist through and then we'll talk a little bit about pathophysiology of both mechanical and non-mechanical causes. And then we'll talk about how you evaluate ridiculous or nerve root pathology. So history exam imaging nerve conduction studies, EMG and CSF. And then we'll go through some cases where we'll take out all that knowledge for a spin. So before we talk about that, Rahul, why do you care so deeply about ridiculous obviously? Why are we doing this three hours? Yeah, it is hard to think about things that I care about more than ridiculous. But it's probably because it's so common. It's so interesting. And I guess it can have really severe consequences for people. That's right. So it's really common. And it's also a really important differential. So a lot of the time when you're trying to figure out what the cause of weakness is ridiculous almost always in there. So it's worth understanding for that reason. And also it causes back pain but it's a relatively minor slice of the back pain pie. So it's really important to differentiate which back pain people have ridiculous things which don't. So it's an important thing that we're all very passionate about. All right. So let's start off with some anatomy and and I appreciate that this is this is not a great format to talk about anatomy. But we will persist because at the moment we are just a podcast group. Nothing more. Yeah, it's a hint that something tantalizing the future. But that sounds great. So to begin with, Beck, what are the nervous? So they're the first bit of nerve exiting the central nervous system. So the most proximal bit of the peripheral nervous system. Exactly right. Exactly right. And so if you think about the neuro anatomy and how it all ties together, you start with the brain, brain connects to the spinal cord, spinal cord connects to the nerve, which is what we're talking about today. Yeah, a one L2 kind of connects to the brachial plexus connect to the peripheral nerve connects to the. You're going to hear first L1 L2 connects to the brachial plexus. Good question. Lumber cycle plexus. So it's worth thinking about anatomy, a new anatomy and that kind of sequence and the nerve roots sit between the spinal cord and the plexi. And so that's the, as you said, the first part of the peripheral nervous system. So one of the important things to understand about peripheral nerve anatomy. So it. Nerve root anatomy is where those nerve roots exit spinal canal. So they exit the spinal canal through something called the neural for Ramina. And the important thing to know about these neural for nap for Ramina is that anteriorly they're bordered on by the interpretable disk. And why do I care so much about the interpretable disk and the fact that the neural for Ramina is bordered on by these structures? Because that's the most common part that gets damaged and then causes impingement of the nerve root. Exactly. So they're more vulnerable than the other borders of this of this opening, which are bones. Yeah, so bones. And so the mind in general is a terrible piece of evolution or desired, but the interpretable disks are particularly terrible and very vulnerable to damage. And so it's important to know that the nerve roots pass by those interpretable disks and that's the most common cause of nerve root pathology. So the next thing we're going to talk about with never anatomy is how the names of the nerve roots relate to the vertebral body names. Between which vertebral disks in which neural for Ramina to the nerve roots exit. And the reason we care about this is because when you're looking at an MRI and it's got the generative changes everywhere and it's got it says it's got a problem with the L4 L5. And so the vertebral disk you need to know which nerve root is most likely to be impacted there. Or you know, conversely, if you're looking at patient and you see that they're going to L5 ridiculous, you need to then be able to go look at the MRI and look at the right interverteable disk space that's going to correspond to pathology at that nerve root. So that's why we care. So the nerve roots are named there's the cervical nerve roots there's C1 to C8. There's the thoracic nerve roots T1 to T12. There's the lumber nerve roots L1 to L5 and there's a sacral nerve roots S1 to S5. And they kind of approximate with the vertebral bodies at a similar level. But as you probably know, there's a very annoying phenomenon here where there's eight nerve roots and only seven vertebral bodies in the C spine. In the C1 to C8, but in the nerve roots, but only C1 to C7 with the vertebral bodies. So that means that in the cervical spine, the nerve root passes above the vertebral body with the same name. So back if we've got the interverteable disk at C6C7, which nerve root passes through there. That would be C7. Yeah. So the C7 goes through the neural phyraminor at the C6C7 level. But then what happens once you get to the eighth nerve root? So that then passes at C7 T1 vertebral body, which means that the T1 nerve root passes between T1 to T2. X, it's the spinal canal at T1, T2. So it's the T1. Now the nerve root is below the vertebral body that has shares the same name as it. Exactly right. And that's how it goes for the rest of the spine. So where is T4, X, T4, 5? L2, Rahul. That L2, 3. Exactly right. And L4 back. L4, X, it's L4, 5. Okay, great. Great job class nailed that. But there's another curve ball with the spinal cord and with nerve roots being affected by interverteable disks. So when you say another, the first one is the Named Glutcher. Exactly right. I don't know why I just started to use that word for the worst word to say. So the change up of being above the vertebral body with the same name to below, whether you never know where it exit. Exactly. So that's curve ball number one and curve ball number two is the fact that the spinal cord actually ends at T12, L1 and something called the cone is metalaris. And so that means all the nerve roots below L1. So that's all the lumbus sacral nerve roots are formed at that level travel down in the spinal canal and something called the quarter a quiner. And then they finally exit at the levels that we were just discussing. So that means that the nerve root actually has a lot of time in the mean streets of the spinal canal to get down by an interverteable disk. There's a lot of opportunity for pathology. It's not just where they're exit, but anywhere really along that quarter a quiner, they can get damaged. So the classic meds called the script is like the spinal cord and then the cone is metalaris at the end. And then there's quarter quiner is like a horse's tail or a little whip coming out the end. So they're all just nerve roots. That's peripheral nervous system below the cone is metalaris. And we care about that because it means that there's a lot of opportunity to be damaged by all the pathology that happens in this terrible piece of evolutionary design, the spine. But you would think, you know, at least they probably most likely to be damaged where they exit, right? Wrong. So it gets a little bit more complicated there. Nerve root in the quarter a quiner is most likely to get damaged at the level above where it exits. So let's go back to our old friend L5 back. Where does that exit again? Third exits at L5 S1 exactly right. And it can get damaged there by the L5 S1 disk. That's certainly a reasonable place for get damaged. But where does it more commonly get damaged Rahul actually above it. So L4 L5 exactly right. And that's just got to do with how interpretable disks tend to herniate and where they're in closest contact with the nerve root. But don't worry too much about that. Just remember that when a nerve root is in the quarter quiner. It's the most likely to get damaged at a level above where it exits. Alright, so as I said that was a terrible format to talk about anatomy and interpretable disks and nerve roots. But hopefully that made some sense. But let's go through some examples. So let's talk about the C7 nerve root. So where is that most likely to get damaged and where is it exiting the spinal canal. So those two questions have the same answer because it's the C spine and in the C spine. The most likely cause of damage is at the level where it exits and at C7. That is C67. Alright, and so the T4 nerve root Rahul where does that exit and where is it most likely to get damaged. So this is where the in the terratheurasex bone is where the nerve root starts to come out below the the vertebral body that's named after us. So T4 will come out at the T4 5 space, the space between 4 and 5. And since we're still in the end of the test, we're going to go through the test. above the lumbus spine, that's the area where it's most likely to get damaged. Exactly. All right. L-5 deck. So where does that exit? And where's the most likely to get damaged? So here's where we're changing things up. Not in terms of the naming, which changed between the C spine and the T spine, but in terms of the actual anatomy. So at L-5, the nerve root is exiting the spinal canal at L-5-S1. But the side of pathology is more, well, most likely to be in the space above, even though it could be anywhere above that, because now we're talking quarter Aquinas. So we say anywhere above between L1, L2 at the cone is between us and where it exits. Exactly. Yep. That's what I meant. So most likely side of compression would be at L-4-5 for the L-5 nerve root that exits at L-5-S1. All right. And very last one, hopefully, a so bored of this because you understand it perfectly, like Rahul does Rahul, the S1 nerve root, where does that exit and where's the likely side of pathology? So again, we're thoracic spine and below. So it's going to exit at the below the vertebral body that it's named after. So S1, S2. So this one is going to get out of S1, S2. However, because we're in that cone, sorry, quarter Aquina, where below the cone is metallarous, it's most likely to get damaged at the space above, which for S1 would be L5, S1. Yeah. All right. And so if you didn't understand any of that or just weren't paying attention, basically just say the second one. And by that, I mean, so at L-4-5, which nerve root is most likely to be damaged, L5 at C6-7, which one is most likely to be damaged, C7. So that's hot tip for ward round if you're just trying to pass scrutiny, but don't do that with your patients, try and understand the concepts for your patients. But if you're getting some questions or it's an MCQ, just guess the second one. All right. Cool. So moving on briefly to pathophysiology of mechanical causes. So as we've kind of alluded to the most common cause of a D-Lopthi is mechanical. And the most common mechanical cause is a slip disk or herniated disk. So disks can at first they bulge and then that's when the GUI center, that the nucleus pole process hasn't actually ruptured through that virus casing, the annulus fibrosis. So it's just bulging. And then when it does rupture, that's that's called a herniation. And then when it completely breaks free of the rest of the disk, that's called a sequestration. May I make an analogy here? Love you to make an analogy. Thank you. I just, I've now I feel like I need to ask for permission to do that. But I, um, have you ever had a suda with the GUI center and has like a hard outside? Remember those? Yeah, yeah. Yeah. So I feel like your disk is a bit like that. It's got the GUI bit in the middle, the pulp osus and then it's got the hard outside. I'm not sure how that ties to understanding the bulging. I'm not sure that's. Advancing, understanding of the disc at all. But, uh, hasn't been agree. I do kind of want to suit the other. Maybe we get a suit of sponsorship. Yeah, I think that the traditional analogy here is the toothpaste tube. I can't. Squeeze the jelly stuff on the inside. You like pop off the lid. Yeah. Interestingly, the discs that are kind of the most severely affected are usually the easiest to treat surgically. And it's an easiest decision to go ahead with surgery. So if you can imagine a sequestrated, a sequestrated disk which is floating around in the spinal canal. That's pretty easy for the surgeon to go in and take it out. And a herniation. It's a bit easier for them to kind of just shave off the nucleus pop osus. But the bulge is the hardest to deal with. So that's kind of like a blessing in disguise. It's got to be one of the few things that the spinal cord has had out back for from an evolutionary design. Yeah. It's a great thanks. Finally, come up with a good. All right. And so which discs are most commonly affected that the ones that have been talking about the most? Yeah. So it's going to be L5 S1 and L4 5. Yeah. Because is it those those areas of the lumbus spine that are the most have the largest degree of flexion? Exactly right. Yeah. Not just the lumbus spine, but the whole spine. Like almost all your flexion comes from those two discs. And that's why if you've got poor deadlift technique or poor picking up technique that you flex over and put all the way to your spine. That's there the discs that slip out. All right. And the underlying cause of all this is the same as many diseases in the modern world age in obesity, basically. All right. So that's a that's a brief discussion of the mechanical causes, but don't forget with the ridiculous. You can get non mechanical causes. Now these are pretty rare, but it can definitely happen. And those can basically be broken into infection, inflammation, malignancy and this phenomenon of chemical ridiculous. So just briefly chemical ridiculous is when you get a disc. Honeation and it heals itself, but then inflammation from the disc. Actually causes some inflammation of the nerve root. I guess that is mechanical at its root cause. Yeah. And it's it's rare, much, much rarer than the mechanical ones, except in MCQ's where I feel like these probably a little overrepresented. Yeah. So all these non mechanical causes are super rare. But it's important to be aware of them because they're all quite serious and are very different. And you can look really fancy on a ward around when you're seeing a patient with a diabetic foot ulcer and someone notices that there's a foot drop. This wasn't me, by the way, I wish it was someone notices that there's a foot drop and it turns out the patient has a bacterium. And they have discitis and the infection has caused inflammation that's pushed on one of the nerve roots and that's why they got a foot job. Yeah, yeah, exactly. All right. So moving on to evaluation. So as always, the first part of the evaluation is history. So you've got two main goals when you're taking a history of someone that you think is ridiculous. Number one is you want to nail down that it's mechanical looking so features of mechanical ridiculous obviously. And number two, you want to exclude any red flags to make sure that you don't think there's anything super sinister going on here. So if you're trying to nail down the features of a typical mechanical ridiculous up there, what are they? So I was looking for, I mean, I think about the classic person who was twinging their back trying to lift up their friends. No, no, no. Baby don't give a fuck on. Yeah, pop. The way it's moving. Obviously. Actually, I find the friend often, often nothing like it's, it's really minor, which is kind of scary. Like on. Yes. So any. So an inciting event that occurs with twisting, talking the back and then back pain or something that looks like a little side of the campaign. So some of it goes down the leg down the back of the leg being the traditional side of the campaign. But I think it's, we do agree, Dive, although the term is now generalized in common parlance to represent any pain that shoots down the leg. No, so I don't. I wouldn't agree with that either. So I think a pain is, yes, and generally referring to ridiculous. So just to zoom in on that pain issue, because that's really important because one of your main differentials, mechanical ridiculous. It's just your axial pain with a bit of a third pain down. That means that the axial pain double. The axial pain is just kind of your barn door back pain due to like a muscle twinge or maybe an osteophyte or some osteoarthritis of the back, but there isn't actually a disc that suddenly perniated and causing a bad ridiculous. So it's really important to nail down to the patient where is most of your pain? Is it mostly in the back or is it mostly running down the back of your leg? So you say like if 100% of your pain in your body, what percentage is that and what percentage is your leg? And that's important because surgery is not really going to help with your axial pain, but it can help with kind of your shooting sciatica like pain. If that's the main problem, then you know, sometimes it's reasonable to do surgery just with really bad pain. So yeah, you've got your inciting event, you've got pain, both your back pain and your sciatica like pain running down your leg. Then you look for your logical symptoms, so numbness and weakness. And then finally, a really important question to figure out whether it's mechanical or not is whether it's positional. So if you think about it, there's a nerve rate that's getting compressed by something a disc. And so most patients are able to find some kind of position that they feel a little bit better. And usually that's lying down. So they often feel better at night. And you've got to worry about those patients that just can't find that position, even all night, they're kind of in release of your pain. So that segues quite nicely in the second important part of the history, which is identifying red flags. So what are the red flags that we look for in patients that they were working out for ridiculous to make sure they don't have something more sinister. Yeah. So if they've got progressive symptoms, if the symptoms are getting worse with time, bladder and bowel symptoms, or some contents or retention. So in terms of the progressive symptoms, with the typical mechanical cause, it's usually bang. I was picking this up and then suddenly I got pain and then it's kind of gradually maybe got a little bit better than that. It doesn't kind of get worse day by day by day. But your bladder and bowel symptoms are is another important one. And then you consider the patient context. So in particular, if they're kind of immunosuppressed, you might be a bit more worried about an infection. Is there anything else in kind of background symptoms that you'd be worrying about? Yeah. Any B symptoms are always worried. Yeah, exactly. And then being those sort of fatigue, lack of appetite, nice for it is weight loss. So they're all suggested there's a stomach. Suspicious going on, particularly cancers, but also autoimmune processes. Yeah, exactly. And then you've got your myopathic features. So that means when you've got more of a spinal cord syndrome, so a CNS problem. And then finally, if they've got multiple. So that's a really good one. So if they've got, you know, elf left, L five, and then, you know, right C seven, that's unlikely to be two discs that have just kind of popped one after the other. So what are you more worried about in that case? I'm actually not too sure. So like an inflammatory cause or like a malignancy cause there they tend to just kind of pick off random roots here. And then often there'll be like a cranial nerve involvement as well. So they might get a facial drip and then they'll get this nerve root and then that nerve root. If that's that kind of pattern is going on, probably not disc. Yeah. So going a little bit off of script here, the two examples you gave just then we're in the lumber spine. So at that point, the, the nerve roots are running as part of the quarter a corner. So if there's multiple lumber nerves affected, not lumber nerve roots affected, is could that not occur from a disc prolapse that's just compressing on the quarter a corner and affecting different reverts within the quarter or quite that can definitely happen, but it raises your suspicion for something else. Exactly right. Particularly if they're not, you know, right next to each other. If they're right next to each other, you're thinking, well, maybe it's just a massive disc. Yeah, particularly in the quarter a corner where they're running closely together. But different random ones in different spots that's definitely red flags and the else going on. Yeah, cool. All right. So moving on to the exam. So you do your typical thorough neurological exam like you do for all patients. So we're just going to focus in on certain things. So talking about power, the main question you've got with power is you need to differentiate the nerve root from the peripheral nerve that can give you kind of like a similar presentation. So we'll go through some of the most common nerve roots that are affected in ridiculous, what they're kind of peripheral nerve differential isn't how you differentiate the two. So starting off with C7 so that typically typically presents with elbow extension, reflection extension and finger extension weakness. What's the main differential for C7 ridiculously back? So all of that extension and the radio nerve. Exactly right. So that's the other thing that can give you a wrist drop. So wrist drop or finger drop, thinking C7 or radio nerve. But there's a particular muscle that I'm pretty sure was just invented to differentiate C7 and radio nerve. What's that? The brachio-radialis muscle. Exactly right. So elbow flexion. So when you're doing an exam and someone you suspect has a C7 ridiculously really going to pay close attention to the brachio-radialis, you might test that three or four times to make sure that it's not weak because that would mean that they've got a radio nerve problem. Yeah and so when you say that's that elbow flexion that's your the kind of beard-rinking movement. So with the hand in. Hand and neck curls for all the guys out there. The gym. All right so the next nerve rhythm we're going to talk about is the L4 that's another really common one. So the L4 does knee extension L4 kicks the doors and the monic I think. And what's the peripheral nerve that does knee extension so what what two differentials you're going to have in your head when you're doing your L4 shortcase. So I think you have the femoral nerve. Exactly that's the main differential here and so the difference between an L4 ridiculously and femoral neuropathy on your power exam is AD-duction. So AD-duction exactly right so hip AD-duction is affected in L4 and it's spared in femoral neuropathy and I've had quite a few cases actually on the ward where that's really helped me differentiate differentiate the two. And then the final the the king of the nerve root pathology the L5 nerve root so that does great toe extension. E version of the foot inversion of the foot dorsi flexion of the foot AB-duction of the hip so does a whole bunch of foot movements and then randomly jumps up and does AB-duction of the hip so that's important thing to remember with the L5. So L5 ridiculously it has two main peripheral neuropathy differentials so back what are they? Perineal and sciatic exactly right. So Rahul differentiating a perineal neuropathy from L5 ridiculously which movements you particularly focused in on. So for perineal I think about one way I think about it is that it's not going to do AB-duction because that's way further up the perineal is quite a distal nerve so it deals with stuff below the knee. So it doesn't do AB-duction. It's not going to do abduction you're talking about the hip. It's not going to do abduction of the hip. That's right so I'm going to do abduction of the hip. And then the other thing is I think of a perineal nerve not being as bad as doing a nerve root just like it seems like a nerve root would be worse and so you don't lose inversion of the foot when you have a perineal nerve lesion but you do lose it when you have an L5. So the two things looking at are AB-duction of the hip and inversion of the foot and if you've lost those it suggests you've got someone going on higher up at L5 rather than the perineal nerve. Exactly right. So there the movements you're really going to focus your examination on. So I should add that these patients are usually present with foot drop and my point is that foot drop can be either L5 perineal neuropathy or sciatic neuropathy. So Beck how are you going to differentiate your sciatic neuropathy from your L5? So I just think of sciatic neuropathy as being the worst one so all the movements of the foot are shot. So we said already that with an L5 neuropathy you lose your dorsiflexion there's weakened dorsiflexion but in if it's just an L5 neuropathy plantiflexion is intact. However in a sciatic nerve injury your plantiflexion is also weak. Exactly right. Which also means you lose your Achilles reflex. I will come to that again in a moment. So I think the I mean love this all of it is very very important well done double thank you. But I think the last couple of minutes is really where the money is from this whole podcast. So in summary the differential for a C7 radiculopathy is a radial nerve paulzy and the differentiator here is the brecchio radialis. And we've got an L4 pathology we're differentiating with a femoral nerve pathology and what you look out there is hip a dduction L5 differentials are perineal neuropathy and sciatic neuropathy and the differentiators there are that hip abduction is only affected in L5. And then with perineal you get a weakness of inversion so you don't get weakness of inversion and sciatic nerve you do get weakness of plantiflexion there the two differentiators. Awesome. Okay. Alright and so the next part of the exam is reflexes which is really important in radiculopathy because a lot of these patients are really bad pain and your reflexes are where you're going to get information. So with reflexes unfortunately we don't have a good reflex for L5 which is the most commonly affected for a lot of the other ones we do. So your biceps jerks which nerve roots innovate your biceps jerks back C5 6 and your triceps jerks what innovates that C7 which is really common one to get. And remember L4 kicks the door so your knee jerk is what L34. Yep and your S1 is what. So that's your acutelys. Yeah. And called jerk. And then for L5 as I said we don't have a good reflex for it but some people are kind of trying to wheel it into existence with something called an internal hamstring reflex. So this is a little bit off in the weeds but basically you can put your finger over the medial hamstring and you can get a reflex there and some people say that that's reduced in L5 but really a lot of nerve roots innovate that reflex. So it doesn't tend to be that clinically useful in my experience. I think you're a reflex. Was that so? Is it easy to get that reflex? Yeah it's really easy to get I think if you're a cool. If you're a medical student I think don't worry about that that's more. It's more a cool medical advanced. All right sensation. So with sensation you basically need to know all your doom and terms so all that study pays off finally when you're trying to look at this patient with a ridiculous ability. But if you don't know your doom terms you haven't slacked off in med school then there's two important ones I want to talk about. So C7 so this is a classic MCQ fodder. What's your C7 doom and tone back? So the main thing is it's limited to the hand it doesn't go up the arm and I test the middle finger. Yeah so the textbooks say it's a middle finger often the patients don't read the textbooks and it can be some other and everything like your index finger but classically middle finger and it's just limited to your hand L5. So your L5 does your the lateral calf but there's a particular part that you can really test differentiate between parent and your nerve which as we know is a main differential here. So the sensation difference between a parent or nerve and L5 are to go up the where do you look around? So you're looking on the outside of the knee and again that's bad by the common barrel near nerve and I think of that as the Compair Neal nerve is really dealing with the lower below the knee sort of stuff. It's actually not spared by the it's actually supplied by the perineal but where you get perineal compression sorry that branches spared so if you've got a common perineal nerve compression usually will get sparing of the lateral knee but you won't necessarily get that in an L5 or D colopthene. That's a pretty soft sign I wouldn't be hanging my diagnostic hat on that but it's a good little extra one to have. So C7 we're looking at the middle finger and L5 the lateral knee. Alright so the last part of your exam which is a bit different to your other new exam is maneuvering. So you might have heard of something called the straight leg rate. So if someone comes in complaining of sciatica down one of that one of their legs, you're going to try and reproduce that by doing the straight leg rates where you flex the hip, extend the knee and then tear on top, or see flex the foot right at the end. And that should recreate the same pain that they get with their radiculopathy. And it should recreating pain down the leg. Exactly right. And it should recreate it no matter which leg you test. So if they're complaining of right sciatica pain, if you do the right leg, they'll get right sciatica pain. But if you do the other side, the contralateral straight leg rate is it's called, they'll get right sciatica as well. So that's evidence that there's a kind of a mechanical cause of the radiculopathy. So it's a good test to kind of really nail down that I think this is a disc, or some mechanical cause compressing the nerve and I'm making it worse with my straight leg rate test. Right. So imaging. So the how your image nerve rate basically has to be an MRI spine. The CT spine is not useful here. It has to be an MRI. And there's certain patients that are going to need an MRI right away that you'll be calling radiology. As soon as you see them, you'll be calling neurosurgery soon as you see them. And they need an MRI kind of that afternoon. And they're the patients that have severe bilateral neurological deficits are bad weakness or progressive neurological deficits getting rapidly worse. Or if you really worry that there could be kind of something infective or inflammatory or malignant going on, they definitely need a patient and MRI. So other patients don't. Yeah, so it's a bit of controversial issues, you know, so some people say that if you've got a band or clinical diagnosis of an L5 radiculopathy, they bent over, they picked something up and they're shooting pain down one of the legs and one of the legs has a bit of foot drop that doesn't look like perineal sciatic. And it's getting better with time that that patient can make a clinical diagnosis of a radiculopathy and you don't. You never need to image their spine. But to be honest, most neurologists, I would say that they would do an MRI on those patients. So most, most neurologists that I know would say that if I'm pretty clinically confident that it is a radiculopathy that I'll do an MRI spine on that patient. And I might as well do it sooner rather than later because they're going to need it at some stage anyway. That's the prevailing opinion that I come across. That's a little bit different to the guidelines to be completely honest. And the reason it's a little bit different to the guidelines is because incidental findings in spine MRIs are super, super common. So one study found that if you just do random MRIs on random people 27% of people without back pain or any radiculopathy symptoms had evidence of discontiation. So you got to be really careful that you don't go kind of barking up the wrong tree. And that's why the rest of your kind of history and exam is really important to now down that this is a radiculopathy. I think this is just a really important tenant of clinical medicine in general. So imaging and investigations should be supporting a diagnosis that's made clinically but not necessarily establishing it. Except for the stroke. Your DWIs, the perfect test. Okay. And tropone and right, right? The arms of half in half air, but troponins are definitely. Pronins are good test. All right. So the other test you can do for radiculopathy, something called a nerve conduction study and EMG electromyography. So I won't dwell on this too much as fascinating as it is. It's probably not really medical student junior doctor level. But just know that with a radiculopathy, the nerve conduction studies will probably be normal and the diagnosis is actually made on the EMG electromyography. Because you basically get when the when the when the nerve root is damaged, the downstream. Muscles, denovate and then they start doing funny things like fibrillating, etc. So if someone comes into emergency and they've just picked up the giant pot plant, they've just started presenting with this back pain. Do it any day. What's the timeline? So usually three weeks. So is you need to give time for those those kind of muscles to degenerate a little bit. How often would you use this to have on how much of that actually help put your. Very interesting question. So glad you asked. It's it. Some people say it's completely useless. So I was talking to a neurologist recently said that I never do this. It doesn't add anything. Neurosurgeons seem to really like it. And we get a lot of referrals from neurosurgeons. And one of the main reasons it's done is for work compensation. All right. Yeah. So if you've re-released this weakness related to that or the muscles of feet, like what's that? Well, if you've got clear weakness on exam, that's enough. But if you don't have clear weakness and you find something on your EMG, then that's enough to get more work compensation, I believe. Then just kind of actual back pain. That's interesting. Okay. Right. What other tests do we do? So there's one other test that we sometimes do not that commonly in that CSF a lumber puncture. So that is not done when you think there's a mechanical cause, but when you think it's one of those other non mechanical causes, one of those red flag causes like an inflammatory cause like sac or something on effective cause like Zoster can cause this. Or a malignant cause like left and then in geodesis like their rear causes of ridiculous up there and usually you'll see something in the CSF you see raised white cells in those cases. But before you go doing a lumber puncture and some of the back pain and ridiculous up there definitely need an MRI beforehand because they could have an epidural abscess and you don't want to poke through an epidural abscess into the CSF. Probably is the end of investigations. I think the key thing to take out of that is that MRI is the most useful investigation, but there can be a role for other investigations. Exactly right. I think it's a good summary. So moving on to management. So non medical therapy first. So we're well beyond the era of telling our patients to rest in bed. So that's not really recommended. So they should just basically do as much as they can. And then some good trial evidence for that. There was a trial that came out in 2020 actually that showed the patients that mobilized early actually to better in the long term, which is good because there's not a lot of evidence in ridiculous. I can say wow a trial in your role. Yeah. That's not something you say. Well, it wasn't done by the new surgeons. I don't think all by the neurologist for that matter. Yeah. Yeah. Yeah. So it's good to have some evidence for that. And that's what we tend to recommend. So moving on to medical therapy. So now we're more stringent to the evidence free zone. So almost all our patients in the short term get insets and paracetamol. And that's one of those things that we do, but even though there's no evidence for it because it's pretty low risk and it seems to work okay. And then if they need something a bit heavier than that, then as you see a lot of stuff get thrown around. And then there's probably harmful to patients and there's no evidence for any of it to go to really tread carefully in this kind of this kind of territory. And I'm talking about things like steroids, neuropathic pain, and particularly lyrical pregablan that gets thrown around a lot, benzo d'Isopens and opioids. So there's no just know that there's no real evidence for any of those personally. And there's lyrica and steroids kind of the most at steroids only in like the very short term. So if I'm convinced that someone's got any flame disc that's causing the ridiculous up to a little bit of steroids might help. And when you're talking about steroids here, you're talking about oral. Exactly. A dislocation. But the benzoes and the opioids as you can imagine, they're pretty dangerous things to put patients with back pain and ridiculous up to and you can get some long term sequelae from them. So and then the other thing you might hear about with management of a ridiculous opathy is epidural glucose, cordicoid injections. So you can actually give injections of a mixture of lignicane and steroids and you can give that right into the nerve root. And that can provide kind of some short term relief. Again, no evidence. Okay. So where's the evidence? There is no evidence. Where is the evidence for what what management is the evidence for any surgeries? Not really. So there's not there's very easy. So why are we talking about this anyway? It's common in poor. What do you think my work back there's enough evidence? Yeah. So moving on to surgery. So there's some cases where like a surgery definitely works. We're never going to get a trial for that would be what we call a parachute trial. And that's things like severe or progressive motor weakness or quarter a corner syndrome. Those patients get rushed strength to theater and it definitely works. We think. And then that's a very small minority of patient. There's a large swath of other patients that have different combinations of bad pain. Sometimes they've just got axial pain. They might have a little bit of minor motor weakness and no pain or some motor weakness and lots of pain or just sensory deficits or sensory deficits and pain is all these different combinations. And how much those symptoms bother the patient will really very person to person and the specific anatomy that we're dealing with, you know, might be more or less difficult to deal with. It really comes down to a conversation between that patient and the surgeon. But generally speaking, most people with really severe pain that hasn't responded to just just kind of simple analgesia in a few weeks of rest will usually get surgery. And so people who have weakness that's disabling in some kind of way we usually get surgery as well. So to summarize, very much in evidence for his own, which is a mark will give him how common and how deciding how bad a problem is, but we just. We really don't know what we're doing. We're shooting in the dark, but neurosurgeons are very helpful to refer to. And as I said, it often comes down to a conversation between the patient and the neurosurgeon. All right. So let's go into some cases and let's test out that knowledge. So we'll start off with this guy called Bob, his 50. He's got no significant past history, apart from some hypertension and some high cholesterol. He's not in great shape and he lives a pretty sedentary life. He's pretty healthy. One day out of the blue, he decides he's going to do some work in the garden. He starts lifting around heavy banks of soil with really bad technique. It's just an all of that flexion of the spine that 045, 05S1 is creaking. He feels a twinge and then bang severe back pain. And then the next day he wakes up with the side of a like pain running down his right leg. So that all sounds pretty mechanical with you. You do the red flag history and there's nothing. There's no red flags. There's nothing to worry about. So the examinim has got normal power, normal reflexes, maybe a little bit of dysesthecia between the in the lateral calf and the dorsum of the foot and maybe between the first and second toes. And he's got a very strongly positive straight leg raise and contralateral straight leg raise. You really recreate that those are adicous symptoms or that side of a symptom going down his right leg. So what do you think is going on here? Does this guy have a mechanical ridicule? Yeah, so I mean we have a clear inciting event and then sciatica like pain and some very clear positive straight leg raise, some other clear signs of sensory disturbance on exam. So it does seem like he does have a mechanical ridicule of his story or his thoughts. Which never do you think is a bulk given where his sensory changes? Yes, that would fit with an L5 sensory dermatome. And if I can cast your mind to the beginning of the podcast, which disc is most likely involved with an L5 ridicule? So because we're in the lumbus spine and you know it comes out to the disc above whatever reason tends to affect the nerve rate below, it's going to be L4-5 despite the fact that L5 leaves at L5S1 exits. That's right. L5S1. Star people. So would you do an MRI in this kind of case spec? Yeah, it sounds like from what you said, we probably would, but the evidence and the guidelines say perhaps not. So it's a little bit of a grey zone, but at our hospital, yes, it would be yes. If Darval was the neurology red trail on the hospital, yes, anywhere else in the world would be better. All right. How do we treat it? So this chap, we strongly encouraged him to mobilize as much as he could, gave him some paneroin urethin. And the pain was still there pretty severe after a couple of weeks in the MRI showed a pretty big disc pathology at L4-5. And so we referred to the neurosurgeons and then they decided between themselves to go ahead with the surgery and he made a pretty good recovery. All right. So the same guy is recovered from his previous injury and he's decided, you know, what, this all happened because I'm old and I'm a little bit overweight. I can't do anything about the age, but I'm going to go to the gym and get a little bit more fit. So he starts dead lifting what he used to do when he was age 30 and he's forgotten his technique and bang, a familiar back pain strikes him and he goes, "Sculpt, back to bed." And in the morning he's got shooting pain down his leg again. But this time it's shooting down the front of his right leg and kind of the middle calf, so it's a little bit different. Is it internal? So he doesn't go to the doctor, but a few days later his right leg starts collapsing on him and he comes to you. So you examine him and he's got reduced power in his right leg proximal muscles. So his hip flexion and his knee extension and you can't really examine him very closely because he's in a lot of pain. But you do notice that he's got a reduced knee jerk on his right side. He's also got reduced sensation down his medial calf and a strongly positive straight leg raise down his right leg. So which bit of the examination did I skip over there and why is it important in this particular ridicule? Pity back. All right. So it sounds like if it is a ridicule, it sounds like probably L4. And what's your evidence for that? So the L4 dermatome is what's been affected. So the medial calf. And L4 kicks the door. His lust is knee jerk. And his lust is knee jerk. And so the other but my other differential diagnosis here would be the femoral nerve. The femoral nerve. Exactly. And so the other movement that you didn't mention doing that would have been good test would be adduction at the hip. So AD adduction. Exactly right. Rahul, which disc do you think is affected with an L4 ridicule? So once again, we're in the lumbar spine. So it's going to be the disc space above the nerve root. So that's going to be the L3, 4 disc. We know that the L4 nerve root exits at the L4, 5 space. But it's going to be L3, 4 that's causing the problem. Probably. Yeah. So he disc ended up having a MRI that showed exactly that and ended up having surgery again. So this time he recovers from the second operation. And this time is like, I really need to get fit. But I'm going to do a bit more sensibly. So he gets back to exercise, but he soon notices that he's got bad pain in his hip. And soon enough, he finds himself in the offices of an orthopedic surgeon and he's getting a hip replacement. And he wakes up from his operation and he notices he can't move his right foot. It's like, oh my god, not again. I've done a disc again. So you're asked to see him. He can't really access this proximal power. He's just had a hip replacement. But he's lost all his foot movements. He's lost his dorsiflexion, his planter flexion. His inversion, his eversion, but his knee reflexes intact, but his ankle reflexes gone. And he's got reduced sensation everywhere below the knee apart from the medial calf. So what do you think is going on here, Rahul? What's your, what's your ridiculous, differential and what's your, guess what? We're looking a lot of stuff at the foot there. And obviously he's just had surgery with the hip replacement so we concerned about some compression on a nerve. So if I think nerve roots, I'm thinking in the L5 S1 region because we're getting down more distal in the legs, it's all foot. So L5 or S1, which one? S1 because that controls his ankle reflex and that's gone here. Yeah, but there's the S1 control, yeah, your foot, your ociflexion. No, it doesn't. So you normally can make any two nerve roots. That's right. So you don't need two nerve roots or potentially we could unite them with a sciatic nerve or maybe you know, one of the cards is always a perineal, common perineal nerve as well. Is it with a common perineal? No, he's got reduced ankle reflex and also he's lost his inversion. And we remember that inversion was preserved in a common perineal injury. And he's also lost his plantar flexion? Yes. So you're two differentials. If you're really committed to the nerve root idea because he's had so many nerve root problems before you have to invoke two of them, L5 and S1. So that seems a little bit less likely. Or maybe he had a sciatic neuropathy because he was in a funny position when they were doing his hip replacement, which is a common, not common, but it can happen after a hip replacement. So this guy's got a sciatic neuropathy and that's confirmed on a nerve conduction study. He probably would still do an MRI of his spine just to make sure that nothing, thank he's been going on, given he's had two operations in the area before. All right, next case. So this guy is actually one of triplets and his sister is exactly the same. She's, she is him in terms of, she's pretty sedentary. She's a bit overweight and she's visiting her brother while he's laid up in hospital with his sciatic neuropathy and she picks something up off the ground for him, boom, certain back pain, sciatica down her right leg and then she notices a little bit of clumsiness with her foot kind of the next day. Your examiner, she's got reduced dose infection in version and eversion, all the reflexes are intact though and she's got a little bit of reduced sensation of a lateral calf, dose mother foot and the great toe. So this probably fits best with an L5 neuropathy, right? You've got lots of dose infection, she's got a foot drop and in version and eversion. But which, which movements would be really important to focus in on your, on your exam to kind of differentiate from your peripheral neuropathy, differentials and why Rahul? So we're really considering three differentials here, L5, the common perineal nerve and sciatic nerve. Exactly right, well done. Yeah, so I'm going to start off with abduction, hip abduction which you lose with L5 but not with the other two. And then I'm also going to look at foot inversion and foot inversion, you don't lose with the common perineal nerve but you do lose with L5 and the sciatic nerve. Exactly right. And then I'm a last, so I'm going to be looking at plantar flexion. Right on. Yeah, with plantar flexion, you only lose that in S1. Perfect. And sciatic nerve as well. Oh, sorry, yes, S1 and sciatic nerve. Which is composed of L5 and S1. So that's the plantar flexion. Okay, great, well done. And if you're going to be super fancy, you can look at just the patch of skin over the lateral need to differentiate. between your common perennial and your L5. It's affected in L5, but not in your common perennial. - It's interesting, I'm gonna sidebar here. - Go on, yeah. - How little variation there is in the nervous, the innovation of people's limbs when it comes to this sort of stuff? You know, like I mean-- - Yeah, it's interesting you bring that up. - A heap of various things. - Unfortunately, it's not our works in the room. - Really? I was just thinking-- - But I know, vascular anatomy, like it's so different in so many people, but this just seems to be-- - Like if you were getting down to the fact that the patch of skin over the lateral knee is a good differentiator, I would've thought that means that it's-- - I would've said it was a good differentiator. I said it was a different differentiator. - I feel like even if you look at different maps of dermatitis in different texts, they're completely different. - I found that so frustrating as a medical student. - But it's because they're completely different people to people. - Okay, all right, well. - Take all of this with a grain of salt, the last hour with a grain of salt. (laughing) - It's a general, general patterns. - All right, and so this second of the triplets, this lady, she also has an MRI, which shows that she has had an L5 ridiculopathy from an L45 disc, and she also ends up under the knife of the neurosurgeons. All right, so this triplet that has had the L5 ridiculopathy, she's drinking her sorrows away and one Saturday night she falls asleep with her arm over the chair after having a few too many beers. And then she wakes up in the morning, and she notices that she's got some arm and hand weakness and some numbness of the lateral side of her arm. She comes to see you examine her, she's got a wrist drop, she's got a finger drop, and she's got some mild elbow flexion weaknesses where all her reflexes are fine, and she's got a reduced sensation of the lateral dorsum of her hand, but also extending a little bit past the wrist. What is a diagnosis back? - All right, this is sounding a lot like a radial neuropathy. - Why do you think that? Zooming on the bits of examination that I told you about? - Yeah, so the bit that made me perk up my ears was, you mentioned that there was a sensory change over the lateral side of the arm, so not just the hand, and so I remember you saying just earlier that one of the key things about C7 is that it doesn't supply a sensation, the proximal side of the wrist crease. So that's making me think that it's the radial nerve, but the radial nerve and C7 have been the main differentials for wrist drop. - What about on the motor examination? What was that? - The motor examination, yeah. So you mentioned elbow flexion being weak. So I'm thinking of the Bricu radialis muscle there. - Nice. - Which is affected in a radial neuropathy, but not affected in C7. There's also sparing of the triceps reflex and elbow extension. - Yeah, which you would expect to see in a C7, but you'd expect to see that in a radial nerve, as well as that radial nerve does triceps reflex. Rahul, why has this lady spared her triceps reflex? - Because it's injured below the exhilar above the elbow in a little fella I like to call the spiral groove. - Name it, that's cool. - I named it. - You named it, it's actually called the Rahul groove. Famous dance move and also a bit of. (laughing) - All right, so yeah, this called Saturday night pause either, and this is a classic bang over neurological presentation. So a radial neuropathy that spares the triceps reflex and spares elbow extension. All right, second last case. So there's another, as I said, there are triplets, so there's the third one. And she is much more active than the other two. Her name's Dorine and she's a keen golfer and she did a really sweet powerful swing. And then she felt a strong pain in her neck and pains her after shooting down her left arm and numbness over her left middle finger along with some left arm weakness. - So you're so sick of this family and their ridiculous opportunities, you just go straight for the money and you think this is probably C7 ridiculous, that's what it sounds like. So what are we gonna see on exam at the C7 ridiculous up to your back? - All right, so you're gonna get some weakness at the triceps, weak wrist extension, wrist flexion, finger extension and pronation of the forearm. - And which movement is gonna be spared? - So you're seeing the main differential of the rotation. - Yeah, so again, that be a drinking muscle, right here, radialis. - Which reflex is gonna be lost? - Tri-sips. - Exactly right. Good, all right. And so she also turns out to have a disc problem where Rahul, she's gonna see C7 ridiculous up to you? - Well, it's gonna be the C6-7 because in the cervical spine, it's coming out above the vertebral body that is named after. So C7 is coming between C6-7. - Good job. And so that's where the MRI shows and she also ends up in the neurosurgeons office. I had last case, so they have an older brother, who's not one of the triplets, he's 60 years old and he also presents with weakness and back pain. He's a heavy smoker, but otherwise has no past history. So his history is a little bit different. He initially has some dysesthesia over his right buttock and then a few weeks later, he's just some back pain and then some progressive bilateral lollum weakness and some difficulty with microtarition with going to the toilet. And then along with that, when you do your red flag history, he tells you, look, I have lost my appetite, I haven't weighed myself, but definitely lost a few belt buckles. And I think I've been having some favors in night's ways. Your examinem is cranial nerve and uplim exam was normal. But all his lollum muscles were moderately to severely weak with a distal worst and proximal. All his reflexes were reduced as well. And he had reduced sensation of the dorsum and souls of both feet and of the calves and buttocks. So this does not sound like a mechanical ridiculousity, would you agree, Beck? - I would agree. So the red flags here are the time course. So it's getting worse, it's progressive over weeks to months. The involvement of bladder and bowel symptoms. And the fact that this is happening on both sides are the bilateral symptoms. And probably the main one that sticks out to me is that this is a man we weight loss and fever. So some systemic symptoms that say to me that we need to think about things like infection and malignancy. - Exactly. All right, so what would you do next? You would do an MRI, but you do an MRI that's a little different. You have to worry about this too much as a medical student, but you would add something called gadolinium or contrast into the MRI. Because that contrast is good at picking up those kind of non-mechanical causes, like infective or inflammatory or malignant causes. And that shows enhancement. So contrast enhancement of all his lumbar cycle never roots, basically. And so you're thinking, this is looking a bit sinister. You do a lumbar puncture, there's no epidural abscessive. It's full safe in doing that. And that lumbar puncture shows 50 lymphocytes, which is an abnormal number of lymphocytes. You're running a lot kind of two to three. Or actually, maximum five. But 50 is definitely abnormal. And so like, okay, this is not looking so good. So you do a CTHS-abdopel, which says you usually would. And you find that it's got a lung malignancy, probably related to that smoking history. But that's a good example. I've seen something similar of needing to be aware of that something is a non-mechanical cause of ridiculous opathy. And it's all really in the history. So I'm taking careful time-course history even in something that seems pretty bad or is always worth while doing. Well, that's it. We've come to the end of this podcast. So what have you guys learned? Something I hope. Yeah, a couple of things. So we've gone through where the nerve roots exit and some of the nomenclature. Exactly right. So we remember that in the cavaque we'll spine the nerve roots pass above the vertebral body with the same name. So c67 is a good example because that's where c7 nerve root passes. But then as soon as you get to the thoracic spine, the opposite happens. The nerve root passes below the vertebral body of the same name. So for t45, that's where the t4 nerve root passes. And that's the same all the way to the bottom of the lumbar cycle spine. But we know that in the lumbar cycle spine, where the pathology is is not necessarily where they exit. Is that right, Vic? That's right. So generally the space above is more likely to be the side of the pathology. Sometimes I think I sound like a gospel creature. And they're right. Maybe I don't sound like a gospel. Maybe I really uncarrased that a quon. I think one of the things we learned is some of the red flags that are used on the red flags. Yeah. You really need to look for progressive symptom, multiple nerve roots and last b-s. Right, what b-s. B-systems and whether someone's immunosuppressed. And then a whole lot of stuff on localizing the lesion, the real neurology jam. So telling the difference between axial back pain and ridicule up the pain. And then differentiating between some of those syndrome. So differentiating in a problem with wrist drop between C7 and the radial nerve. in foot drop between L5 common perineal and sciatic nerves and then telling teasing apart an L4 pattern of weakness from femoral in the extension problems. Ne extension and so weakness and sensation. If you somehow nailed that into your brain you would just be so far ahead of everyone. Like it took me a long time to remember all that. It's same simple now when you could just read text. Read text books into the microphone or the NSA. If you somehow nailed that into your brain, you're ahead of the normal med student. I thought I'm doing it. Yeah, well hopefully at least one positive thing to come out of this is that maybe our voices sound better. Now that we've got all this new sound recording equipment, however we're going to be honing out understanding of all these fancy buttons and lights that are everywhere and so hopefully it'll continue to get better. That goes wow, do I hold that? I don't think that really came through probably because we now have a live track of all the stuff. I didn't see why you did that. Just a cheering for whenever I localize another lesion. Okay, well for your attention for this hour long blockbuster and we'll see you next time. Thanks for listening. Bye.