If you’ve been following my blog for a while, you’ve probably seen this absolutely incredible TED talk by Dr. Elliot Krane, on the nature of chronic pain. It is seriously one of my favorite things to watch. Chronic pain is terrible, but it’s always so hopeful to me to keep track of how much we’re learning through scientific research.
One of the things Dr. Krane mentions in this talk, which was back in 2011, is the role of a type of nervous system cell called a glial cell in chronic pain.
For a long time, scientists didn’t think glial cells did that much, in terms of affecting our overall function. Instead, glial cells were believed to provide a supportive rule, providing support and nutrients to other types of cells within the nervous system.
However, a new line of research has been identifying the fact that glial cells actually do way more than we give them credit for, in their own right.
Fast forward to 2018: turns out researchers at Massachusetts General Hospital as well as the Karolinska Institute in Sweden have just published a groundbreaking new study on the role of glial cells in chronic pain.
For this study, researchers used brain imaging techniques to test for the level of TSPO, a chemical related to the activity of glial cells, in several different parts of the brain. They compared the level of this chemical in the brains of patients with fibromyalgia, as well as the brains of healthy subjects for comparison.
Not only did they find that fibromyalgia sufferers had much higher levels of the marker, but they also found that the amounts of this chemical present– and therefore, the level of glial cell activity– was actually correlated with the amount of fatigue reported by patients.
This is super fascinating because it shows that glial cell activity plays a role not just in our perception of pain and pain sensitization, but also in the debilitating fatigue that many fibromyalgia sufferers report.
Because a study like this is able to demonstrate this link so clearly, that opens the door for researchers to further investigate drug therapies which can target the glial cells, meaning we will someday have more options for chronic pain.
I’ve been concentrating so much on writing my SI joint blog recently that I haven’t been writing so much about pain science, in general.
But the past few weeks, it’s been hot. Really hot.
And now I’m reminded, on a personal level, how central sensitization really isn’t just about pain. Instead, it’s about everything our central nervous system is responsible for regulating… and the fact that our ability to regulate it has been thrown off.
Something that should be so small, for another person… for people with central sensitization, it can be huge.
I’m about to tell you why I’ve been so miserable, and why, so far, I’ve spent most of the weekend just lying on my bed.
As I write this, I feel like what I’m going to say sounds so silly, so benign. But this is the reality of struggling with central sensitization– our symptoms can sound ridiculous to other people. They can even sound ridiculous to us. But they are still happening.
So I will tell you that my apartment is too hot.
I should spare you the boring details, but this post won’t make sense if I don’t explain that this is my first summer in this new apartment. I don’t have central AC in this place, as I have in summers past. I’ve been trying to get away with one small window air conditioner for my whole place, and it’s been an epic fail.
I know what I’m saying might sound ridiculous to the average person. Because it’s not really a big deal, right? Just buy another air conditioner and move on.
But for me, this situation is reminding me, so strongly, that I really do have a problem with central sensitization.
Because sometimes, my body doesn’t let me just “move on.” It’s not just like I just noticed that I felt hot. I’ve been exhausted.
I feel like I didn’t get any warning. I didn’t just have some mild discomfort and then think “oh, I should probably do something about the fact that my apartment is so hot.”
Instead, it hit me like a ton of bricks. Like a virus.
Originally, I’d wanted to wait and see if one AC was enough, before buying a second. When it first started to get hot a few weeks ago, I thought I could just spend most of my time in the bedroom (my air conditioned room) and limit my time in the rest of the place.
As the summer’s gotten hotter, I’ve found that I don’t just get hot. I get exhausted, quickly: I can’t think clearly. I go on anxiety spirals.
I’ve constantly felt like I’ve been coming down with something… but I haven’t actually gotten sick.
If I leave my air conditioned bedroom and walk into the 82-degree living room for 5 minutes, I get dizzy.
This is crazy, right? I know it sounds crazy. It doesn’t make sense!
But that doesn’t mean I’m not also experiencing it.
I noticed that if I retreat back to my 74-degree bedroom, after about 20 minutes, I’ll start to feel calm again. My anxiety will go away, and my thoughts will become rational again.
But apparently, I really can’t handle even the back and forth to the rest of the apartment, even if I have my cool bedroom to go back to.
I know plenty of people who live this way, no problem.
And I know a few people who barely use their air conditioners at all.
I know that what I’m experiencing sounds extreme. And yet, it’s happening.
I think it’s a heightened version of the way everyone gets tired, when they’re overheated. It’s how our body protects us, by forcing us to stay still and keep cool.
Only my body is perceiving the walk from my bedroom to the kitchen as a threat to homeostasis– or, in other words, its ability to keep things regulated.
Honestly, I was getting pretty upset, when I remembered to do what I always do, in the end: slow down. Take a deep breath. And do some reading. Remember that there is a name for what I’m experiencing, and that I always feel better when I try to learn about it.
So I went back and watched my favorite video from Dr. Sletten at the Mayo Clinic:
I shared this video in my last post too… I guess I probably can’t share it in every post (or can I?!). But it really pulled me out of the depths of despair right now, so of course I had to share it again. (Thank you, Dr. Sletten! I’ve never met you but I feel like I’m your biggest Internet fan!).
This video is really the most reassuring thing I’ve found out there.
In the first screenshot, which I took at the 2:30 mark, Dr. Sletten outlines some of the various systems our body uses to maintain homeostasis:
He explains, “If you’re too hot, you might to go to a place to cool off. If you’re thirsty, you might drink some water. If you have to go the bathroom, you go to the bathroom.” These are all ways in which we respond to the input that our peripheral nervous system gives us, in order to take care of our body.
As he says, “The signal itself is not abnormal.”
The problem sets in when these signals get upregulated– meaning a stronger and stronger signal gets sent to the brain.
The somatosensory cortex is the part of our brain that processes all of these sensations coming from our body. When these signals are upregulated, that means they’re stronger and more uncomfortable.
In the red marker below, you can see where he wrote a list of some of the sensations and triggers that can arise when the nervous system has been sensitized. He included temperature as a potential trigger, as well as a change in barometric pressure (which I, personally, haven’t experienced, but I would imagine this would make people feel as crazy as I feel right now).
So, honestly.. I don’t really know how to fix this.
I’ve come a long way in managing the chronic musculoskeletal pain aspect of this, using an awesome approach called pain neurophysiology education. But that doesn’t mean that central sensitization is completely reversible (although new treatments are being researched every day!).
For now, I personally feel better if I can just learn about it.
To know there are other people out there going through the same thing, and that there are doctors and researchers out there who won’t think I’m crazy. To know that it’s not “in my head,” although it is in my nervous system.
I just need to know this about myself. I have symptoms of central sensitization, and one of them is that I don’t handle heat well. Temperature is not something I can be too flexible with.
Does anyone else out there experience this?
I know this post was not my normal cheerful, upbeat post. I’m genuinely curious if anyone else out there goes through this.
Dr. Sletten’s video helped me a lot, but if anyone else out there feels the same way, please let me know!
And, whether or not heat is a factor for you, I hope you’re enjoying the summer!
Me… I’ll be off to buy another air conditioner now. :)
One of the original reasons I started this blog was to get the word out about the various pain scientists and educators whose work has touched my life (including, but not limited to, Neil Pearson and Lorimer Moseley).
From them, I’ve learned that pain isn’t here to make us suffer (although it seems like it sometimes). Ultimately, it’s here to keep us safe.
It can “zoom in” or “turn up the volume” on pain signals it thinks you need to pay more attention to. This is what I call the “up” dial.
Your body can also turn down the volume on pain.
There may come a time when your nervous system decides it’s more important to “turn down the volume” on pain– or even block out pain signals completely.
Normally, this “down dial” isn’t something we are able to access consciously. It’s something our body can do automatically, in times of great danger, if those pain signals are distracting us from getting out of a dangerous situation.
Neil Pearson, for example, tells the story of a patient he once treated who had been hit by a drunk driver on the way to work. He woke up upside down in his burning car, and realized he had lost an arm in the accident.
The man managed to extricate himself from the car, collect his missing arm, and walk back up to the side of the highway all without feeling any pain. This is because, in that moment, his body knew that feeling pain would take away from his chances of survival– the most important thing was his getting to safety. Once he was safely in an ambulance in his way to the hospital, then the pain set in.
Your body has the ability to adjust the level of pain you perceive.
This is a survival mechanism that normally kicks in under emergency circumstances.
However, it is something we can also learn to do consciously with practice, using various techniques to tell our body to “turn down the volume” on pain. That is the focus of pain neurophysiology education, the approach to pain management that changed my life.
My own metaphor
The really good news about this approach is that you don’t actually have to be a neuroscientist, or even have a huge scientific background, to learn how to do it.
Somehow, once you start to switch over from viewing pain as an enemy to a friend or a guardian, it can start to make an immediate difference in how you perceive it.
That’s why I’ve been so determined to spread the word about some of the metaphors that have helped me. However, I’ve felt a bit limited in doing this, since I’m also interested in not plagiarizing other’s work.
So today at long last, I got my own metaphor.
It’s not particularly wild or dramatic. In fact, it’s pretty subtle (and also makes me not sound terribly coordinated). However, I think it does a great job of explaining in a down-to-earth way exactly how the nervous system can choose to turn pain signals out, if it benefits your survival to do so.
It’s a small thing, really. (And actually, it illustrates to you how absent-minded I can be at times, but that’s another matter!).
I was cooking dinner, boiling some ravioli. They looked about done, and I was starving. So, without really thinking, I lifted the pot off of the burner with one hand, and started taking it over to the sink to drain.
Halfway to the sink, I realized the pot was much heavier than I’d anticipated. I realized I hadn’t really been paying attention, and it had been a mistake to pick it up. Now I felt like my wrist was about to give out, and I was already halfway to the sink.
I quickly thought through my options. I wanted to put it down instantly, but there wasn’t a clear space on the counter. I wanted to put another hand up to steady the pot, but the handle was too small and I would have needed a potholder.
My wrist was really starting to hurt, and for a second I considered just dropping the pot altogether.
But no. I had a vision of scalding water splashing everywhere, including on me, burning my skin.
And just like that– that very second– all the pain in my wrist disappeared.Nope, my body said. We are NOT dropping a pot of boiling water on ourselves today.
My nervous system made an executive decision, in that instant, to block all the pain out. Ultimately, the prospect of spilling boiling water all over myself was more of a threat to my survival than the pain in my wrist.
I was able to get the pot of water all the way over to the sink without incident. About 30 seconds after I put it down, that’s when the pain came back.
Like Neil Pearson’s patient making it safely into an ambulance, my nervous system had blocked the pain out just long enough for me to safely put the pot of water down. Once that was over, the pain came back, to remind me that indeed, I had put my wrist through something strenuous.
It’s been a few hours and my wrist is just a little bit sore. I know it will go away– it wasn’t a permanent injury or anything. I just strained it a little bit by trying to carry something it wasn’t strong enough for. (This is a good reminder that I need to pay more attention in the kitchen, even if I am spaced out and hungry!).
But I wanted to share this with you because I think it provides a good example of how pain isn’t always a clear-cut indicator of what, exactly, is going on in our body.
Instead, it represents our body’s “safety monitoring system,” warning us about potential threats to our survival, and making sure we choose the course of action that’s most likely to keep us safe.
Of course, if you have chronic pain day in and day out, it can be hard to see pain as a protective mechanism.
I said it was a protective mechanism– I never said it always perfectly.
Sometimes in the case of chronic pain, the “up” dial can get stuck on.
That’s why, again, it is so important to know that your pain also has a “down” dial, and that, with practice, you can learn to access it.
I hope you found this post helpful!
For more on the metaphors which can help you understand pain, I recommend you check out my posts:
Okay. I’ve really been looking forward to publishing this post.
Here, we’re revisiting the same great talk by pain physician Dr. Jay Joshi. In my last post, I outlined what Dr. Joshi says are the four main categories of pain.
Central sensitization is the type that is, unfortunately, the least understood. And it’s also the type that’s had the biggest impact on my life to date.
What is it?
Central sensitization is a process through which the central nervous system learns to become more sensitive to, or amplify, pain signals.
I struggled with it for years and thought I was crazy, because I had pain that came and went throughout my own body that most of the doctors and physical therapists I saw couldn’t explain.
Central sensitization is a form of memory.
Generally, we think of central sensitization as a sort of a disorder, because of course, it causes so much pain and suffering.
However, as I’ve touched upon in previous posts, central sensitization actually has its roots in some of the same neural mechanisms that allow us to learn new things and store memories. We “learn” from pain just as we learn from anything else, and our nervous systems can be changed by it.
As Dr. Joshi says:
“Central sensitization is what happens when the brain is exposed to certain experiences or certain memories. It’s life… it’s being a human.
When you have a certain memory that forms it, becomes part of who you are… it becomes part of your experience. And your behavior changes as a result of that.
This is not something that happens randomly… This is something that happens to the neurophysiology of your brain. It forms memories. Those circuits get hardwired on your little ‘hard drive’ that’s known as a brain. The same thing that happens with pain, when you have a chronic pain stimulus.”
The process of central sensitization is not separate from our brain’s other functions– rather, it belongs to them.
I found this happened to me so often, over the years, before I even knew what central sensitization was.
I’d have a painful experience– the first one was when I threw my back out at age 21— and it was like my nervous system was determined not to let me forget about it afterwards.
According to Dr. Joshi, this is exactly how central sensitization occurs, after a painful or traumatic event:
“You have a painful experience, and usually one of the first things that happens is your brain says ‘hey don’t do that again.'”
It’s trying to protect you from doing the same thing that might have caused you to become injured in the first place.
But what happens when that signal doesn’t stop?
In cases like mine, this process can go on indefinitely. Your brain keeps trying to protect you, telling you not to repeat certain activities, long past what’s actually necessary or conducive to your well-being.
This is called the wind-up phenomenon— when the brain’s protective mode stays on, and never gets the signal to turn “off” like it should. Instead, it just keeps repeating the message of “don’t do that again”– even if it’s something that, technically, should be safe for you to do.
Once this process, the pain can sort of build on itself, like a snowball effect. And you can remain in pain, long after the original injury that might have set all this off as healed.
Does all chronic pain cause central sensitization?
Dr. Joshi explains that chronic pain is likely to lead to some degree of central sensitization. (This is significantly higher than other estimates I’ve heard, such as Dr. Elliot Krane’s figure of 10%).
However, I think Dr. Joshi’s explanation makes a lot of sense. After all, when you experience chronic pain, you’re basically bombarding your nervous system with opportunities to practice sending pain signals. Why wouldn’t it get better at doing so, the same way you can get better at playing the piano or riding a bike?
Central sensitization is still a part of my life.
I don’t expect to ever be able to totally reverse the process that first began, for me, at age 21.
However, I was able to make a lot of positive changes and gain back a lot of control over my body through pain neurophysiology education, which I write about a lot on this blog. (Basically, it involves teaching your nervous system what it’s like to feel safe again, so that it can turn the “volume” back down on the pain).
There’s a lot more to say!
Dr. Joshi has some great thoughts on how to improve the medical profession’s understanding of central sensitization, as well as ketamine infusions– a potentially powerful treatment for patients with central sensitization.
I’ll be sharing more on this coming up– hope you liked this post!
I’ve just discovered this awesome talk on central sensitization by pain management physician Dr. Jay Joshi. It’s totally packed with information I want to share with you all– such as why it’s so hard to get help for central sensitization, and how ketamine infusion treatments can help. There’s so much here, though, that I thought I’d break it down into bite-sized information for you.
So, to start out, let’s look at what Dr. Joshi says are the four main types of pain. (For the purposes of this blog post, I’m actually jumping ahead to the 8:50 mark– later, we’ll come back to the beginning).
2. Neuropathic pain: involves physical damage to the nerves or the central nervous system itself. It can also occur when the person has a tumor that’s pressing upon a nerve.
3. Inflammatory Pain: Pain produced by the chemicals our body releases as part of the inflammatory or healing process. On a small scale, think of how a bruise swells up and is painful to the touch. This is because our body is sending special cells and chemical messengers to that part of our body in order to heal it– and also to make it painful, so that we know to protect the area. This is inflammatory pain, and it can also happen on a much larger scale with more serious injuries.
4. Central Sensitization: And here we are– the type of pain that’s most affected my life. It has to do with the concept of neuroplasticity: that the central nervous system (the brain and spinal cord) can change in response to the things it experiences.
When your body experiences a painful event or an injury, it learns from that experience, the same way it learns from anything. Practice makes perfect– when your brain gets enough practice at sending pain signals, it gets better at it gets better at it. In a way, this is for your protection– you learn and become more sensitive to performing the same kinds of actions or motions that may have caused this injury in the first place.
However, as a protective mechanism, central sensitization can sort of backfire. Eventually, we can reach a point where our nervous systems are trying to protect us too much, when we’re not really at risk of injury anymore.
So these are the four main types.
Unfortunately for those of us suffering from central sensitization, it’s the type of pain that doctors and other medical professionals know the least about.
As Dr. Joshi explains, “there are physicians who claim to be pain physicians… who are anesthesiologists… who don’t even understand it. And they’re teaching at major programs. It’s scary.”
Central sensitization is as real a type of pain as any of the other three. And, as Dr. Joshi says, if you’re going to be able to adequately treat pain as a doctor, you better be aware of all four categories.
Dr. Joshi also has some really great analogies which help to explain the phenomenon of central sensitization further. I’ll be elaborating on some of those in my next post.
I hope this was helpful!
Also: you may have noticed that I’ve been playing around with my blog’s format. I’ve honestly never truly been happy with the appearance of my blog, because I find my options are so limited with premade WordPress themes. I’m beginning to experiment a little (and even spend a little bit extra!) to try to get things right. If you have any thoughts or suggestions how improve the appearance of my blog, please let me know!