Want to know what truly fascinates me? Chronic pain. There are lots of definitions for chronic pain, but most sources agree on this one:
Pain that is persistent and lasts longer than 12 weeks can be classified as chronic pain.
With most injuries (let’s say a sprained ankle) you injure yourself (tissue damage). There is an inflammatory reaction (your foot becomes swollen and looks like a balloon with toes sticking out) and you probably feel some pain with certain movements (if you try to run or jump). But body is on the ball and starts working to heal the tissue injury (building scar tissue). You find that slowly but surely your range of motion and activity tolerance improve, the pain and swelling dissipate and you’re back to playing soccer in 6-8 weeks. Yay!
But what if the pain doesn’t go away? What if the tissue is healed but you still feel pain? What if the pain you feel is way out of proportion to the severity of the injury? What if the pain is still there six months later? What if you still can’t put weight on that foot, it hurts to touch it gently and you can’t stand putting a shoe on because it feels like too much pressure?
This is the realm of chronic pain and it can have major implications on physical and mental well being. People start to get told “it’s in your head” and “suck it up” and “it should be better by now”. The reality is that we are only just starting to understand the complexity of chronic pain.
There is no “set” pain response.
A certain injury does not cause a pre-calculated level of pain. Everyone’s experience of pain, even with similar injuries, vary greatly.
How we act and react can depend on many factors such as stress and the “threat level” of the injury.
We have lots of receptors throughout our body (in our skin, joints, etc) that recognize lots of different things such as sharp vs dull, hot vs cold, light vs firm pressure, etc. When that input is noxious (irritating or damaging) those signals are sent by nociceptors. When enough of these signals get sent to the brain all at once the brain interprets them and decides how to act.
Some different scenarios for you: maybe your brain feels like something tickles and so it sends a signal to you that you should squirm, maybe you are getting a massage and it “hurts so good” but you decide to keep still even though it’s not comfortable, or maybe you stepped on a a nail and your brain decides that the situation is dangerous and immediately moves your foot away from the nail. In each instance, your brain got a nociceptive input but decided to react in different ways depending on the situation. That interpretation of danger and threat level is important and helps determine how you feel about the input you are experiencing.
How you perceive your injury and how it impacts your life has a huge role in how you feel pain.
A classic example is a paper cut. It is small, it is mighty, and it is a total pain (pun intended) for everyone. But who do you think will feel more threatened from that paper cut - a violinist who has a concert tonight or to a soccer player who has a game next weekend? If I was a betting woman (I’m not but let’s pretend) I would guess the violinist will panic - “oh my gosh can I play? Will I have to miss the concert? Is everything ruined?” - and that paper cut will probably throb all day long. Switch to the soccer player who probably thinks “Yup, that sucks, but as long as I’m careful reaching into my soccer bag I’ll probably be fine” and then goes on with his day and forgets about the paper cut. Those two people had very different reactions to the same injury.
The amount of tissue damage cannot predict the amount of pain experienced.
I know this seems strange. If you have pain you assume it’s because something is injured right this very moment, but in chronic pain this is not always the case.
Let’s start with amputees who have phantom limb pain. If someone’s foot is gone it’s impractical to think that they can have an itch on their big toe or an ache in their ankle because there is literally no remaining tissue, so how could it be damaged and send signals to the brain if there is nothing there to be damaged? And yet there are many reports of amputees feeling pain in their lost limb. On the other extreme, some people have severe life threatening injuries and feel no pain at all. Soldiers with gunshot wounds will sometimes report not realizing they were hit until after the situation calmed down. Their body was so busy in survival mode that it didn’t have time to stop and worry about a major wound.
This also happens with knee arthritis. Some people have “brutal” X-rays that show severe knee degeneration but report only minor stiffness in the morning and no impact on their daily function. These folks can still walk, garden, etc. Other people report debilitating pain that stops them from doing simple daily tasks such as standing and walking for more than a few minutes at a time but their x-rays show only mild degeneration. We cannot rely on X-rays or MRI’s as a way to determine how much pain someone is in. The longer you have pain the weaker the correlation between pain and tissue integrity.
The longer you have pain, the more efficient your body’s pain warning system becomes.
It’s like it has practiced and practiced and practiced sending those signals up your spinal cord to your brain and it becomes really good at it. This starts to get more complicated but to oversimplify we start to call this system “sensitized.” It’s like your body has turned up the volume button on the radio - a simple input on one end (light touch) is over-represented and feels overwhelming and loud at the other (which gets interpreted as extreme pain). The brain is being told there is more danger at the tissue than there actually is. This often leads to pain avoidance behaviours (it hurts when I move so I’m going to move less) even though the joint and muscle are completely physically capable of moving.
Chronic pain is not “all in your head”.
There are legitimate physiological processes that lead to chronic pain. The good news? Your body did this as part of a protective response for you. There was a real or perceived threat and your body said “Not on my watch! I’ve got your back.” Your body is not silly - it wants to keep you safe.
The other good news? If your body wound up this much in response to a need it can also down-regulate when that need is no longer present. That means going back down to pre-pain levels! It means feeling like you are in control of your pain instead of it controlling you.
You just need the tools so it can get the message “thank you for your help but your services are no longer required. Chill out.”
If you would like to do some more learning here are some awesome resources:
TedTalk by Lorimer Moseley, who is absolutely brilliant and it really explains a lot of how interpretation of stimulus can influence pain. Honestly it’s one of my favourite videos.
Here is another good intro that I like - “Tame the Beast”
If you prefer to do some reading anything by David Butler or Lorimer Moseley is great. They have a book called “Explain Pain” which is a great read.
Neil Pearson is a local (B.C.) man who has done a ton of work with chronic pain. His resources are also quite good.
Okay friends, I’m outta here for now. Happy reading!
