Have you ever in your life experienced pain? Lorimer Moseley, a world renowned pain researcher (and of course physiotherapist extraordinaire), says jokingly that if you have a head you have experienced pain. You’ll see specifically why he makes this joke below.
Last weekend I took a course for the first time in a long time. Due to a number of personal circumstances, formal learning activities have not really been in the realm of possibility for a while. The thing is, I had almost forgotten how much I love learning. The course was fantastic with a great group of physiotherapists and an amazing instructor. It really lit a fire under me and renewed my passion for helping people, so I wanted to share with you some of what I learned.
The Science of Pain
First we went through some updated information on pain science. Back when I went to physio school we were taught that the body has nerves that conduct pain signals to the brain. These signals, when received by the brain, cause us to say “Ouchie! Ouchie!” Well, at least that’s how my three-year-old son puts it. In other words, we were taught that pain was a message received by the brain from the thumb we just hit with the hammer.
Many years later (too many for me to admit), we now know that there is no such thing as a pain signal. What we do have are nerves that sense three potentially dangerous things – extremes of temperature, mechanical damage (e.g. a cut to the skin, extreme pressure, a broken bone), and harmful chemicals (e.g. a chemical burn). These nerves in effect create danger signals. They alert the brain that something has gone wrong and there is a potentially dangerous situation. The brain then takes this danger signal, puts it into the context of everything else that is going on at the time, checks its memory banks for previous similar experiences, and then decides what its response should be.
For example, if you just hit your thumb with a hammer, the brain’s response would most likely be pain, and let’s admit it, perhaps a string of words not fit for your children’s ears. But what if at the exact moment you hit your thumb with the hammer your toddler fell crashing down the stairs into your workshop? It is most likely that you wouldn’t feel any pain in your thumb as you rushed over, heart in your throat, to see if your little one was seriously injured. As you picked up your screaming child to comfort her, adrenaline coursing through your body, your brain busy trying to decide whether to call 911 or jump in the car and head to the hospital, do you think you would even be noticing your thumb? Probably not.
How is it that in one situation you would feel intense pain and in another you would have none? It is because pain is an OUTPUT of the brain and not an INPUT from the tissues. Pain is a response entirely created by the brain. Wow, that’s revolutionary.
If the hammer hits your thumb when you are alone in your workshop with nothing else to worry about, then your brain decides that pain is the appropriate response. This most certainly gets your attention and makes you stop what you are doing to go tend to your injury. If the hammer hits your thumb when your child has just potentially seriously injured himself, the brain decides that pain is not helpful under these circumstances as you have more important things to worry about at the time.
This is not to say that we can avoid all pain just by training our brains. It is most certain that once you are reasonably assured that your child is going to be okay (or have at least handed them off to a trusted individual whose thumb is not smashed), the pain in your thumb will hit you with a vengeance. Pain is a safety mechanism designed for self-preservation. It lets us know not to walk on that broken leg until it’s healed. It alerts us to that infected appendix before it bursts. Pain has a very useful purpose and so we cannot avoid all pain, but the pain response can be modulated.
Past Experiences Influence Pain
One of the biggest modulators of the pain response is past experience, particularly if there is strong emotion tied to it. If we follow the above example, say a month later you are at it again with your hammer, this time just barely tapping the corner of your thumb. Your danger receptors send a message to your brain saying your thumb has been exposed to pressure. The brain takes that message and searches its memory banks for similar experiences. It pulls out the last incident where you clobbering your thumb is linked to the very strong emotions you felt when your toddler fell down the stairs at the same time and everything in your world felt threatened. Now your brain’s response is an all-out red alert resulting in a greatly increased pain response in your thumb that is way worse than when you smashed it full on a month ago.
On the other end of the spectrum, if you were a carpenter and hitting the corner of your thumb was a fairly regular event, was not tied to any particular emotional response, and had never resulted in significant injury, your pain response would be much less.
Past experiences and the emotions attached to them are major determinants of the degree of pain response the brain creates. The input from the danger receptors when received by the brain is processed and linked to a whole host of other factors, all in less than the blink of an eye. The amount of pain we feel is in no way related to the degree of tissue damage and is very much an individual experience. The human body never ceases to amaze me and I’ve been studying it for very long time.
Chronic Pain
People who experience chronic pain are often told, “it’s all in your head”. My answer to this is, “ALL pain is in your head” so to speak. Now that we know that all pain is created by the brain, this “all in your head thing” seems less problematic. These quotes from leading pain science experts should help.
“All pain is produced by the brain. This doesn’t mean for a second that it is not real – much to the contrary, all pain is real. In fact, anyone that tells you ‘it’ is all in your head, implying that therefore ‘it’ is not real, does not understand physiology.” Lorimer Moseley & David Butler, Explain Pain
“Pain is whatever the experiencing person says it is, existing whenever the experiencing person say it does.” McCaffrey and Beebe, 1989
People who experience chronic pain have altered brain and nerve chemistry that causes their danger receptors to start to fire long before there is physical threat to the tissues. Once these danger signals reach the brain they are amplified and produce the red alert which amps up the pain response. This can occur even with a stimulus, such as a light bump, that would not produce danger signals in someone else.
As an example, I remember a client with chronic pain who was in my previous place of work one day. She was getting changed behind the curtain when she suddenly started screaming in pain. What had happened is that she had stepped on a staple that was in the carpet and had gotten a small prick in her toe. For most of us this would have produced a small pain response, but her brain produced a huge pain response based on her altered brain and nerve chemistry and past experiences in which almost everything was painful for her.
The more the brain produces a pain response, the better it gets at doing it. It’s like an orchestra that keeps practicing the same song over and over. This is what perpetuates chronic pain. How do we break this vicious cycle? Well the answer to that is complicated and multi-faceted, but one area that definitely needs to be addressed is calming the entire nervous system.
Mindfulness and Meditation
Those who experience chronic pain are often told that meditation and mindful movement helps, but they are not usually told why. The reason it is helpful, is it helps calm and re-program the nervous system. It has been shown to alter brain chemistry and so has the potential to change the pain response. Mindful movement combined with breath awareness can reset the nervous system by providing novel input. In other words it can sort of confuse the brain into producing a different response. Allowing someone with chronic pain to move in a pain-free manner while gently nudging tolerance levels helps achieve a different brain output – less pain.
The science behind pain is evolving and the knowledge base is growing. I have barely scratched the surface here, but I hope I have made it somewhat understandable. If you would like to know more, check out this TED talk and this presentation both by Lorimer Moseley. While he uses a lot of medical jargon in his talk, I still think through his stories he gets the message across. If you have any questions come and see us. We would love to help you live a more pain-free life.