Central Sensitization, Pain Neurophysiology Education, Pain Science

Todd Hargrove: Seven Things You Should Know About about Pain Science

As I’ve mentioned recently, two things make me really happy, which I plan to focus on more in my blogging in 2017:

  1. Great explanations of pain and the nervous system
  2. Amazing writing and creative use of language

Well, this fantastic article on pain science by Todd Hargrove at Better Movement has both, so of course it had to be my next post.

This is one of those moments where I would just blatantly copy and post the whole article if I could, because it’s that good.  However, in the interest of avoiding copyright infringement, I’m not going to do that, and will instead highlight some of the quotes that really resonated with me.

Basically, the term “pain science” reflects an understanding of the concept that pain is more complicated than our body relaying us a simple message about something being wrong.

That brings us to our first quote:

Pain is defined as an unpleasant subjective experience whose purpose is to motivate you to do something, usually to protect body parts that the brain thinks (rightly or wrongly) are damaged. If you feel pain, it means that your brain thinks the body is under threat, and that something has to be done about it.

The key phrase here is “rightly or wrongly.”  Your brain will cause you to feel pain if it thinks some part of you is in danger.  And the brain is not always right about this– it’s not that simple.

Pain is created by the brain, not passively perceived by the brain as a preformed sensation that arrives from the body.

When a body part is damaged, nerve endings are triggered and send warning signals to the brain. But no pain is felt until the brain interprets this information and decides that pain would be helpful in some way – for example to encourage protective behaviors to minimize further damage and allow time for healing.

Pain is not a simple game of “telephone,” where your nerves send a direct message to your brain about what’s happening in your body.  Pain is something your brain chooses to have you experience, in order to motivate you to do something about it.

This is why there have been documented cases of people who were experiencing extreme injuries or states of physical trauma, yet felt no pain.  When I took my neuroscience course, my professor told us that this phenomenon was reported somewhat widely during World War I, where were soldiers who lost entire limbs in battle and yet felt no pain.  This is because, at the deepest level, their brains understood that they were now going home to safety, away from the battlefield.  In the grand scheme of things, the injury could actually be saving their lives.  That is why their brains did not need to make it more painful– they were already heading home to safety.

Pain is like learning

I have discussed central sensitization before– the unfortunate truth that the more chances the nervous system gets to “practice” sending pain signals, the better it becomes at doing it.

Well, here is another way of explaining things that I absolutely loved:

One unfortunate aspect of pain physiology is that the longer pain goes on, the easier it becomes to feel the pain.  This is a consequence of a very basic neural process called long-term potentiation, which basically means that the more times the brain uses a certain neural pathway, the easier it becomes to activate that pathway again.

It’s like carving a groove through the snow while skiing down a mountain – the more times the same path is traveled the easier it is to fall into that same groove.  This is the same process by which we learn habits or develop skills.  In the context of pain, it means that the more times we feel a certain pain, the less stimulus is required to trigger the pain.

I love this metaphor about carving a groove through the snow.  The more times you go over the same thought pattern in the brain, the more firmly you establish it.  This is true for learning a new skill, and it’s true for sending pain signals.

And again, it’s important to remember– this sensitization does initially serve a purpose:

Most of the time an injury will increase the level of sensitization, presumably so that the brain can more easily protect an area that is now known to be damaged. When an area becomes sensitized, we can expect that pain will be felt sooner and more strongly (so that we do not reinjure it).

There are many complicated mechanisms by which the level of sensitivity is increased or decreased…For our purposes, the key point is that the CNS is constantly adjusting the level of volume on the pain signals depending on a variety of factors. For whatever reason, it appears that in many individuals with chronic pain, the volume has simply been turned up too loud and left on for too long.

Basically, our bodies cause us to become extra sensitive to pain following an injury so that we rest the area.  (After all, as my neuroscience professor liked to ask, if you were a cave person with a broken foot, what good would it do you to go out and try to do battle with a saber-toothed tiger?  You’d get eaten.  Better to rest).

However, the problem with central sensitization is that, sometimes, our bodies don’t know how or when to stop– “the volume has simply been turned up too loud and left on for too long.”

The good thing about pain science is, of course, that it provides us with some really interesting entry points to try to break in to these complex pain problems and develop ways to treat them.  (I don’t know why I’m saying “us.”  I’m not part of the “us” yet.   But I so want to be).

So… not to worry.  Just because your nervous system has become sensitized and ended up one way, that doesn’t mean it isn’t possible to change it back.  (And that, my friends, is the main reason for my blog).

Further Reading

If you’d like to read more about pain science, well… I have so many things I think you should read!  But here is what is probably a more manageable list:

Anything and everything by Neil Pearson

Lorimer Moseley & Body in Mind

The nervous system and chronic pain

Understanding pain as your body’s alarm system

Understanding pain as an overprotective friend

What is pain neurophysiology education?

My new and updated “Resources” section!  I have been working on polishing it up recently, so you may find a few cool new things in there that weren’t there the last time you looked.

That’s all for now– please let me know if you have any questions!   Happy reading!

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