Radicular pain is a clinical diagnosis, so you don't need an MRI to diagnose it. If someone has pain down the back of their leg, if that pain is worse than any pain they might have in their back, if they've got like a positive straight leg raise, if they've got pins and needles, numbness, that kind of thing, we're building up evidence that someone has radicular pain. And nothing's certain, but if you have enough evidence, you can make a provisional diagnosis.
SPEAKER_00:There are a lot of definitions of pain going around at the moment. Neuropathic pain, radicular pain, referred pain can be a little bit confusing. And then the question that comes up is, does it actually matter to our treatment? Today we had Tom Jessen on and he's written extensively on the topics of radicular pain, sciatica, chronic pain and clinical reasoning. I really enjoyed this episode. It helped me get my definitions straight and then answer the question, does it really matter? I hope you enjoyed this one. My name is Michael Risk. This is Physio Explained Welcome and thank you for joining us, Tom.
SPEAKER_01:Thanks for inviting me, Michael. Appreciate it.
SPEAKER_00:We're going to get straight into this first question and something that I was saying I personally struggle with and I know a lot of young therapists too. the definitions between neuropathic pain, radicular pain, referred pain, discogenic pain. And I know you do a fair bit in the sciatica space. So could you start with maybe how we define the differences between all those definitions? So the first thing
SPEAKER_01:to say is a lot of them overlap, which is often where the confusion comes in. So radicular pain is a kind of neuropathic pain and they also overlap clinically, right? So lots of people have radicular pain and referred pain. And the other element of confusion is that these definitions are all just kind of made up. The world is a complex place. And then we put these labels on stuff. And so the other thing is like, if you see patients and it's like, I don't really know what kind of pain this person has, like, don't worry too much about that. People are complex and definitions are often quite simple. And that doesn't mean they're useless, but it does mean sometimes they don't really explain the world that well. But to take them in order of what you said, neuropathic pain, is pain caused by a lesion or a disease in the somatosensory system, nervous system. So for us, that means things like radicular pain, I guess carpal tunnel syndrome often. We see actually fairly few neuropathic pain conditions. Tarsal tunnel syndrome might be another one. The true serious neuropathic pain conditions are things like painful diabetic neuropathy, postherpetic neuralgia, trigeminal neuralgia. So those are conditions where people describe severe, shocking pain. Often they'll have numbness, pins and needles, things like that. As I say, it's caused by a lesion or disease of the somatosensory system. What does that mean? Typically, most cases that physios see that that lesion or disease will be some sort of compression. So the space in the carpal tunnel will be too tight. The space in the lumbar spine or the cervical spine will be too tight and it'll press on a nerve and basically injure it and piss it off. When nerves are injured, they start sending off all sorts of crazy information that they shouldn't send off. So action potentials emanate from that injured bit of the nerve and go up to the brain and the brain kind of freaks out and interprets that as pain. So we think about like, quote unquote, normal pain. If you tear a hamstring, then there'll be lots of inflammatory mediators in the hamstring. they'll trigger all the little nerve endings. Those nerve endings will fire off action potentials that go up to the brain and the brain kind of registers that as pain. And like, that's normal pain. Neuropathic pain is when that nerve itself, like let's say it's in the lumbar spine or in the carpal tunnel, that nerve itself is injured. And so it starts sending off those action potentials, even though there's nothing wrong in the hamstring or in the fingers or anything like that. So yeah, it tends to be different. As I say, it's often more severe, shocking, there's often pins and needles, tingling. And because the nerve is injured, it doesn't work very well. So there's often numbness and weakness too. Neuropathic pain is a funny one because it's quite a strict definition. People argue about what true neuropathic pain is. Sometimes people with carpal tunnel syndrome, they don't actually have shocking pain and it's not that bad. And people say maybe that's You can get into the weeds about whether that's really neuropathic pain, but I guess the only thing you really need to know to get started is that neuropathic pain is when a nerve, a sensory nerve, is injured. The nerve itself is injured.
SPEAKER_00:Is there a distinction then with radicular pain from that? So radicular
SPEAKER_01:pain is a kind of neuropathic pain because it is a nerve injury, right? And radicular pain is when one of the nerve roots... in the spine is injured. And radicular is a weird word, but it just comes from the Latin word for root, radix. So radicular pain is really just medical language for root pain, nerve root pain. And as people kind of probably remember from school, the nerve roots come off the lumbar spine. So each spinal level has a pair of nerve roots. In the neck, the nerve roots come off and branch down the arm into the tips of your fingers. So if you get a nerve root injury in the neck, then often you'll have pain in your fingers, which is a weird, weird thing. And in the lumbar spine, the nerve roots branch off and then they travel a bit as a cauda equina. So you've got that hanging horse's tail of all the nerve roots. And then they go down the buttock, the leg, tips of your toes. So if one of the nerve roots of the lumbar spine is injured, you often feel pain. And numbness and tingling and all those things in the buttock, leg, tips of your toes. So radicular pain is just a sort of medical language for nerve root pain.
SPEAKER_00:The other thing that strikes me is we're talking very structural and what we're learning is pain is an experience, right? So even if there was a disc pushing on a nerve, that may not account for the full experience of pain. Does that resonate with you and what you're learning?
SPEAKER_01:Yeah, absolutely. Yeah. There's a temptation to go both ways with this, isn't there? So like, I think traditionally and certainly in popular culture, right? Disc herniates, splurges all over the nerve and squashes the nerve and it hurts. You know, I'm a physio network reader. I think most other readers will know that that's not the full story. Loads of people have disc herniations that don't hurt for whatever reason. And there's also the temptation to go in the other direction and say that, Well, disc herniations are irrelevant and they don't matter for pain. And that's a bit too far in the other direction for me. Certainly, disc herniations are maybe like a trigger or a spark for radicular pain. They're one of the causes. But also, you know, you need a lot of other stuff to go wrong in that nerve. So Some people are lucky and let's say a disc herniate slowly and gently presses on the nerve root. The nerve root has plenty of time to adapt and the blood keeps flowing through it and they maybe won't even know it's happened. If some people are unlucky and they get a big disc herniation very quickly that squashes a nerve root, the nerve root doesn't have time to adapt. The blood can't flow through it properly. So it becomes ischemic, starved of oxygen. Inflammation starts to build up. It can become swollen as well. So surgeons describe very swollen nerve roots as when they operate on them. it's a proper injury and very often those can become painful. So yeah, I think completely agree with you. There's a lot of steps in between that disc herniation and pain as well, because we also know that there's some weird magic goes on in the brain, which I don't understand. So, you know, you can get plenty of nociception and the brain can just not care, right? So there's some weird magic that goes on in the brain too. And we have to be humble, don't we, about not knowing exactly how these things happen. But certainly for many, many people, a disc herniation eventually does cause pain. And we know that because very many people get significant pain relief from having them removed in an operation.
SPEAKER_00:Yeah. I appreciate these definitions because I feel personally the needle's moving and some of the definitions are changing. So thank you for running through it. Before we get onto sciatica, while we're on discs, is there a distinction for you when you're looking at a patient with back pain, is there something where you'll say, I think this is discogenic? Are there any triggers there or flags in a history that you might think of? So
SPEAKER_01:I think the distinction to make at the start, which is whether the person has back pain or leg pain. And people debate this, and I don't think there's a definite answer, but in my opinion, I think it's very hard to tell what's causing someone's back pain. And, you know, we have to talk about non-specific back pain and whether we should call it that, but I'm quite cautious about whether we should, the phrase discogenic back pain is difficult to me. When it comes to radicular pain, it's probably easier to start blaming structures for that in a sort of, in a more straightforward way. You can guess if a patient has discogenic radicular pain. So let me back up a little bit, if that's okay. Radicular pain is a clinical diagnosis, so you don't need an MRI to diagnose it. If someone has pain down the back of their leg, if that pain is worse than any pain they might have in their back, if they've got like a positive straight leg raise, if they've got pins and needles, numbness, that kind of thing. then we can start to, we're building up evidence that someone has radicular pain and nothing's certain, but if you have enough evidence, you can make a provisional diagnosis. As to what's causing that radicular pain, it's more difficult because certainly a disc is one of the causes. So particularly in young people who have more hydrated discs, there's more pressure. And so those discs are more likely to herniate. People who describe pain that suddenly comes on when they they bend down or they feel something go and they bend down. And then in a few days, they start to feel something in their leg and it gets worse and worse as the inflammation builds up. Often that kind of makes you think it's more of a disc problem. Older people who get like a more gradual onset of pain, who don't have that classic pattern, who have maybe more pain with side flexion, that type of thing. Then you're starting to think maybe it's more of a stenosis type problem. So it's just, they're getting old and the bones are kind of narrowing in on the nerve and crowding it out. So, you know, you can start to make guesses about whether that radicular pain is discogenic based on the profile. I don't know how clinically meaningful that is. I can only think of that it really, really matters if you're thinking about surgery. And even if it's that bad, then you're going to get an MRI before you make any surgical decision. And that MRI is going to help you to decide whether it's discogenic. So does that sort of answer your question?
SPEAKER_00:That's helpful for me because how I interpret that another way is if someone's just got this vague central back pain and there's no distal symptoms, all those distal symptoms aren't worse, it's very hard to say what it is. But if they have radicular pain, we have to at least make some assumptions somewhere up the line, something is pushing on a nerve and that could or could not be the disc. Is that correct in saying? And if it's not, please correct me.
SPEAKER_01:Yeah, I'm happy with that. I think of it as almost like you got a bit more permission with radicular pain. I think it still is a bit more of one of those biomedical reasoning helps a little bit more. It doesn't mean we forget the biopsychosocial approach, but it helps a little bit more. And yeah, you can start to assume that something is crowding out that nerve a little bit, whether it's a disc or an overgrown ligament or some stenosis. And then there's other weird and wonderful things like infections as well to think about. And of course, serious pathology, yeah.
SPEAKER_00:Yeah. And then so finishing where you love to speak about is sciatica. And is there anything you would do with a patient when you're using that umbrella term sciatica? So assessment wise, would you try and rule something in or out? So you mean sort of what's my approach if someone
SPEAKER_01:has pain down at the back of their leg? Yeah. Yeah. What would you do in that scenario? Yeah. Probably not too different from what most people would do. I'd want to kind of get an idea that it's from the lumbar spine. So the other competing thing is going to be the hip joint, right? Or in my opinion, the hip joint is one of those ones where you do have a good special test left, which is, how do you pronounce it? Fadio? Anyway, flexion, adduction, then internal rotation. And if that doesn't hurt and there's nothing else that hurts the hip, then... Nothing's ever black and white, but that's some pretty good evidence that it's not the hip. And then you can start moving the spine around. And once I've located the pain to the lumbar spine, then I guess this is where we have to introduce another new word to define, which is referred pain, right? So referred pain is really common. It's when you feel pain in an area other than the source of the nociception. So a good example of this that everyone can understand is a heart attack. So, you know, on Coronation Street or neighbors or whatever, if someone's having a heart attack, they don't clutch their heart, right? They clutch their left arm or maybe their side or something. So if I think that someone's got pain down the back of their leg that's coming from the spine, I would like to know if it's radicular. So if it's that neuropathic pain or from the nerve root, because the nerve root is injured, or if it's just referred pain. So pull the muscle, pull the ligament, whatever in their spine. No one really knows what's going on in there, do they? Something is going on in the spine and they've got back pain, but that back pain is kind of creeping down into the buttock and the leg, that sort of thing. So I'd like to kind of differentiate between radicular pain and referred pain. And again, there's no test to do that. It's just that old thing of you weigh up the evidence for one against the evidence for the other. And I actually mentioned some of these before. So radicular pain usually not always is worse in the leg than in the back. There's usually more neural tension, other neuropathic pain descriptors. So tingling, often there'll be patch of numbness or weakness on examination because the nerve itself is in pain below the knee, that kind of thing. Whereas classically referred pain can make it below the knee, especially SIJ pain, which I forgot to mention before. You use Laszlo's tests for that. But it's usually worse above the knee. And usually referred pain is quite diffuse and vague, whereas usually radicular pain is a little bit more sharp and a bit more specific. So people will be able to point more precisely to where it hurts. And again, with referred pain, often people will have a bit of neural tension, but it won't be that oh God, I can't tie my shoelaces, neural tension, you know? So it's nice to differentiate. And people might sometimes say like, well, why, like who cares? Why does it matter? And I think it matters because it's helpful and therapeutic for patients to have as good an idea of what's going on in their body as they can have. And so the more that you can educate them, the more in control of the situation they are. And because for radicular pain, there's certain treatments which are effective aren't effective for referred pain, so injections and operations. Medications is a different topic. They're going out of fashion now for good reason. I think that fewer and fewer antineuropathic medications prescribe, but it really is a different treatment approach. So
SPEAKER_00:it's good to know. Thank you so much, because I genuinely think that that episode is so helpful. The definitions are helpful. The general sense I get from the young health professional community is that We are shifting away from specificity and in many places that is good and helpful for us and our patients. But as you've actually just finished on there is when it's ridiculous pain, it is helpful because the treatment would be different and definitely empowering for our patient. So thank you. I really appreciated you going through all those definitions and your time today. Where can people find out a little bit more about you?
SPEAKER_01:The best thing to do is easiest thing to go to tomjesson.com. And then you can follow a link. There's a newsletter where I try to regularly write something useful about sciatica. In the resources section, there's a good article which covers a lot of what we just talked about with a bit more depth. And the lecture or masterclass I did for you guys, that must be over a year old now. And I was kind of worried that it would be rubbish. But I look back on my slides and I was like, oh, thank God, this is pretty good stuff, actually. So I'd say watch that as well. Awesome. Thank you for your time,
SPEAKER_00:Tom.
SPEAKER_01:My pleasure, Michael. Take care.