Cervical Disc Degeneration and Neck Pain: What Does the Latest Research Say? | Podcast Ep. 352

Foreign hello and welcome to the Evidence Based Chiropractor. I AM your host, Dr. Jeff Langmaid. On today's episode, we are back with the research taking a look at a brand new study in the Journal of Pain Research called Cervical Disc degeneration and Neck Pain. Controversial topic. Does degeneration cause pain? Is it correlative? Is it causative? Is it totally something separate? We're gonna take a look at what the latest research has to say about this, which in my opinion includes a ton of clinical pearls that you can apply with the conversations you're having in your practice. This is the latest research and it is a good one. Before we get started, I want to say a few words about the smart chiropractor. If you've been looking to generate more new patients, better retention or, or more reactivations without spending any money on advertising, come on over and check out what we have going on at the Smart chiropractor. That's at thesmartchiropractor.com thesmartchiropractor.com As I said at the top, we're talking research today. Cervical disc degeneration and neck pain. Brand new study. I'm gonna drop a link to it down in the show notes. It's the Journal of Pain Research and it came out just within the last couple years. Now, a couple things about this study is it is highlighting what we know and where the research is going around the intersection of disc degeneration and pain. Why is this a big deal? Well, neck pain has big numbers. When we talk about mean point, annual and lifetime prevalence rates, we're talking nearly 8%, 37% and, and nearly 50%. So at any given point in time, about 8% of people have neck pain. Over the course of a year, about 37% of any body of people, any body, meaning any population of people have neck pain. And over the course of a lifetime, almost half of human beings will experience neck pain. So is this a big deal? Absolutely. Is it also one of the top three reasons why people visit a chiropractic practice? Absolutely. So it is something that not only are we being asked about a lot by our patients, but these are conversations we should be having with other healthcare professionals and with the public continuously. Because I like to say if you're not proactively answering the questions people in your community have about their health, you are probably not going to be generating the new patient numbers that you'd like to. So getting out there and answering questions people have about their health and especially touching on some of these really, really big, big common topics are a great way to lead the conversation in your community. Because if you're not, who is going to do it? So what can cause pain in the neck? Well, there's a couple different things. You know, any innervated neck structure can theoretically cause pain. That could be muscle, could be the synovial joints, the discs, the dura mata, the ligaments, all of these can theoretically cause pain. Now, when we look at the disc specifically, a lot of times this is mediated through the sino vertebral nerve. That's important to keep in mind as we'll talk about later on. Why? Because intervertebral disc innervation in the cervical spine is pretty analogous to the lumbar spine. So cervical discs receive innervation posteriorly from the backside, posteriorly from the sino vertebral nerves, laterally from the vertebral nerve, and anteriorly from the sympathetic trunk. Now, why does this matter to us as a chiropractor? Because if you have somebody that's ever gotten nerve blocks, they're going in and chopping off these nerves. So understanding the approach, what's going on with the nerve block, the other thing that's important to keep in mind is there's three different points of innervation. There's, you know, cervical disc posteriorly from the sino vertebral nerve. That's traditionally what is taken in a nerve block. But that still leaves laterally the vertebral nerve, potentially, and certainly it leaves the anterior portion from the sympathetic trunk. So how good of a procedure is a nerve block? Well, we'll leave that for another day. But the bottom line is there are multiple innervation points, which is a good thing to know and a good thing to guide your patients on when they have questions. A couple other things to keep in mind is that there has been previous research that suggests the change of structure and function in the cervical disc with degeneration and can be related to neck pain. Now, I know this is all over the board. We've heard that it does cause degeneration, is causative to neck pain, and we've certainly heard the complete opposite. And there are plenty of people, don't get me wrong, walking around all day with supremely degenerative discs that don't have pain. That's just the fact of the matter. So there's a lot of variability here. But neck pain, as we know, is usually accompanied by things like stiffness, headaches, unilateral or bilateral shoulder pain, non root related arm pain, ocular vestibular dysfunction, pain in the anterior chest wall. It can be pretty varied. Now in the course of this study, one thing to keep in mind is they're specifically speaking of things that are non radicular. So non traveling pain, more of your axial type pain. So degeneration of the disc has been linked to elevated levels of inflammatory mediators. Now here we start to get into the good stuff. So there's elevation of inflammatory cytokines when there is degeneration. What are those? Well, there's a laundry list of them, but it's il 1, 2, 4, 6, 8, 10, 17, 20 and more are all secreted by the disc cells and the cytokines. These cytokines upregulate, they upregulate nerve growth factor, which it's a big deal because this is something that, that causes the pain, the innervation of the disc. In a very simplistic fashion, a young disc, a fresh disc has very little innervation. Therefore there's very little pain signals going from the disc up to your brain. So you recognize that there's pain. However, as we age, as degeneration occurs, as these cytokines upregulate nerve growth factor, the now we start to see invagination. We see growth of these nerve fibers into the outer portions of the disc and continuing on as far as they can get to the inner portion of the disc. Now that's when you start to feel the pain because before it was basically, I wouldn't say a de innervated structure, but a minimally innervated structure. However, with disc degeneration, weird irony here, as it degenerates, the nerve fibers kind of go in. So the onset of the inflammatory condition inside of the disc is a trigger that can produce a whole bunch of pathogenic stuff, apoptosis, nerve and vascular ingrowth, all of these things can proliferate. That pain and the onset of discogenic pain is characterized by definition by nerve fiber ingrowth into the otherwise aneural tissue. So the tissue in the disc brake, by and large, especially as you go deeper into the center of the disc, there is absolutely no nerve growth there, very minimal if any. But over time as injuries happen, as degeneration happens, we start to see those nerve fibers go in. So sensory neurons involved in anti inflammatory pain perception are typically small nerve growth factor dependent peptide containing neurons. Maybe a little deeper than you want to go with the patient there, but important to know as a clinician, additionally the increased levels of nerve growth factor in the disc and the breakdown of the agricans will Lead to the ingrowth of nociceptive nerve fibers. So when you see that nerve growth, here's the cascade, so to speak, we start to get inflammation and degenerative changes, especially inflammation that starts to stimulate cytokine activation, all of those ils, so that starts to stimulate the cytokine activation. When that happens, that's when there's an upregulation of nerve growth factor. When that happens, nerves start growing, tissue starts to become innervated and along with it becomes the vascularity and the sensory nerve fibers that you start to say something is going on there. So in one way you can say it's a really wise way for the body to do things. It's de innervated structure. As it degenerates, as it becomes suboptimal, you start to see nerves grow into it. And then you start to recognize mentally that there might be pain in that area. Let's say great function in one way. In another way it's not a good function. Because as time goes on, as you age, as you're under the way to gravity, you start to notice these things happen more and more and pain pop up. So there was an increase in pain related fibers in both degenerative and herniated cervical discs. Also interesting there because the contents of the nucleus pulposus are known to directly activate and sensitize nerve fibers. Nerve fibers growing into degenerative and herniated discs might provide a potential explanation for these clinical findings. So another interesting thing right there. Let's break that down a little bit. There's not only pain related nerve fibers, an increase in them when a disc is degenerative or inflamed and these kind of things can, they don't always, but they can go hand in hand. But also in herniated discs. Now that's interesting. Now we also know that when a disc herniates or when there's an annular tear, historically, most of the time, of course there's always exceptions in the dynamics of who we are as people and as health in general, how the body works. However, we know an overwhelming majority of the time when a disc herniates or when an annular tear happens, there's a lot of inflammation that occurs. That is usually what causes most of the pain. Everything gets super super inflamed in that area. That's what causes the inability to move all of the irritation. The those areas are super highly inflamed. Now the interesting part of that is inflammation is what stimulates the healing process. So that's why usually taking NSAIDs is not a good idea. It stops the healing process. But the catch 22 here is that when the cytokines are getting in that area, it also is bringing nerves with them. So that's why you really want, when we talk about that transition, as we did a few weeks ago, from acute to chronic pain, you can. It's okay to have that inflammation spike up really fast, but it should be coming down quickly as well. That's an acute pain cycle. That's normal. However, when you have that acute spike of inflammation and it stays there, it stays inflamed. More cytokines, more cytokines, more cytokines, more inflammation, nerve growth going in, no surprise that that leads to chronic pain. So putting together a few different concepts here that I think are really just important to revisit and understand, because as we have these conversations with our patients, this ties to expectations of health and healing. So in my opinion, really, really important conversations for us to be super aware of, for us to have really command knowledge of, and then to be able to explain to our patients. So we know that although an MRI may identify a degenerative cervical disc, it does not differentiate which disc is pathologically painful from which is just physiologically aging. I used to talk to my patients about this all the time. And I would say your MRI or your imaging, the report for that, and what I'm going to explain to you is like a deck of cards. I took the deck of cards, I threw it all out on the table. My job as your doctor is to find which one of those not perfects. So every one of those cards is a not perfect. There's all 50 of these, 52 of these cards, 50 of these cards spread out. Looks like there's a ton of them. But my job as your doctor is to separate the not perfects from the problems. You might only have one or two problems, but you are going to see a lot of not perfects. Don't worry about the not perfects. Just like all these cards on the table, my job is to find the one or two that really matter for you. It's an easy metaphor, and it's an easy way to kind of visually understand what you're doing as a doctor. And for your patient to be like, okay, I got that rapport. It looked like I had stuff going on at every single level. I thought I was ruined. I thought I was too far gone, forgot chiropractic. I thought I might need surgery. Hold on a second. Our job is to look through all of these not perfects not perfect is okay, but our job is to find what the problems are. And to me, that's the heart of who we are and what we do. So discogenic neck pain alone, without cervical herniation or spondylosis accounts for most chronic neck pain. And the reported prevalence of this is between 16 and 41%. So what does that tell us? It tells us it's a big deal. So no herniation, no spondylosis, There's a lot of chronic neck pain. Why is that? In my opinion, there's a variety of factors for this, but there's a couple tying the threads that we've woven together on this episode together. Number one is inflammation is important for the healing process. But inflammation shouldn't stick around forever. And when somebody is highly inflamed, they have a much higher likelihood of transitioning into a chronic pain state. And that we know based upon the physiology and biology of what we see here. Cytokines flock to an area, inflammation's occurring, nerve innervation occurs, pain results. Very linear, very clear. The other thing to keep in mind, again, as we highlighted a few weeks ago, NSAIDs can actually inhibit the healing process. And that is a real, you do not want to elongate this inflammatory process. And part of that is when you, I guess chemically or superficially or artificially is probably the best word, try to change it, it doesn't work out well, it elongates it. And as you elongate that process, you increase dramatically increase the likelihood that somebody's gonna move from acute to chronic pain. So doing the most natural things possible to get an anti inflammatory response is really, really important. Now, you can approach this in a variety of different ways. Is it heat, is it ice, is it supplements? You can choose to approach this however you want. In practice, however, it's really important to be in tune with and aware of if somebody's taking NSAIDs like Tic Tacs. All this is an important conversation to have. Not that we're going to recommend medications. As chiropractors, we want to stay out of that lane. But it's important for our patients to understand the decisions that they're making and specifically.