Tonight, I’m going to try out a type of post I’ve been wanting to write for a while: taking a scientific journal article on central sensitization, and translating it into plain English for my readers.
I got the idea from Paul Ingraham of PainScience.com. He has a fantastic “jargon-to-English” article on central sensitization on his site (a translation of a paper by renowned pain researcher Clifford Woolf), which I really love.
There is no reason why you, as a patient and chronic pain sufferer, should not be able to know a little bit about the scientific research being done on your condition. You are going to need to be able to advocate for yourself, stand up for yourself, and remember there is a legitimate explanation for your pain, even if other people don’t always see it that way. Knowing there is research to back you up helps.
Ever since I first learned of the term “central sensitization” back in 2011, I found so much comfort in reading these articles. Even if I didn’t understand every word, just knowing there were people out there who would believe me about my pain, if I met them, provided me with the sense that I wasn’t alone.
These changes to our nervous systems are real, even if some of the people in our lives don’t always understand.
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So anyway. The article that I want to take a stab at tonight is “Central Sensitization: A Generator of Pain Hypersensitivity by Central Neural Plasticity” by Alban Latremoliere and Clifford J. Woolf. (In the interest of keeping things manageable, I am just going to outline the abstract, which is basically a summary of the article).
The article discusses central sensitization, which is the name of the process through which our nervous systems learn to become more sensitive to pain.
Let’s look at it in bits and pieces:
“Central sensitization represents an enhancement in the function of neurons and circuits in nociceptive pathways caused by increases in membrane excitability and synaptic efficacy as well as to reduced inhibition…”
This basically means that the parts of the nervous system responsible for sending pain signals become more active than they were before.
“Increases in membrane excitability” means that it will take less stimulation for nerves to send a pain signal.
An increase in “synaptic efficacy” means that the nerve is going to learn to be more efficient with the neurotransmitters that it has. So, even though the nervous system still has the same chemicals floating around in it, it is going to learn to start sending stronger and stronger pain signals with those same chemicals.
Reduced inhibition. Your body has many intricate systems of checks and balances within it. It is how our bodies maintain control over our internal environment.
One way our body maintains control is by “inhibiting” some of the signals our nervous system sends. This serves a really practical purpose– we do not need to be bombarded with reminders that our socks are a little bit itchy at all times. Your nervous system chooses to block out certain signals when they are not useful, or in emergency situations (which is why people can feel no pain when they are in shock).
But in the case of central sensitization, our body’s ability to “block out” or “turn the volume down” on pain signals is reduced, meaning we ultimately experience more pain.
“Central sensitization is responsible for many of the temporal, spatial, and threshold changes in pain sensibility…”.
There are several ways in which these changes to our nervous systems manifest themselves.
We may find that, when something happens that we find painful, we end up experiencing it as painful in a larger part of our body than we might have otherwise.
I’ve really found this to be true with back pain. When my back pain was at its absolute worst (before I discovered pain neurophysiology education) one tight muscle or muscle knot could make my entire back hurt.
“Because central sensitization results from changes in the properties of neurons in the central nervous system, the pain is no longer coupled, as acute nociceptive pain is, to the presence, intensity, or duration of noxious peripheral stimuli.”
This means that, in a sensitized nervous system, pain is no longer an accurate measure of the presence of an injury, or the degree to which our tissues may have been damaged by an injury. The central nervous system is now doing its own thing, and you can’t really go by the pain to know what’s wrong.
“Instead, central sensitization produces pain hypersensitivity by changing the sensory response elicited by normal inputs, including those that usually evoke innocuous sensations.”
This means that we now start to feel pain in response to things that are not harmful, and which would have felt painful to us before.
To give you an example, I once knew someone who also suffered from chronic pain, and she said there were days she simply could not bear the feeling of clothing against her skin. Just the feeling of a lightweight sweater against the skin of her chest made it burn and throb.
This person wasn’t crazy. She knew her clothes weren’t “hurting” her. But her nervous system was reacting as though those clothes were somehow damaging her skin. There was a disconnect between her rational mind, which knew it was only clothing, and the parts of her nervous system which were contributing to her pain hypersensitivity.
(So… lest I end the post on a gloomy note, not to worry. That’s where pain neurophysiology education comes in, to try to fix this disconnect).
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Phew. Okay. That was not quite as easy as I thought it would be, all the times I thought about writing this post. But hopefully you made it through!
Everything I write on this subject is meant to be a trial, of sorts. I’m experimenting with what types of stories and explanations make the most sense, because I really have it in my heart of hearts to develop a set of educational materials on these nervous system changes.
So I want to see what works– what makes sense, what resonates. (And what doesn’t).
I suffered for so long, thinking I was crazy, when the whole time there were answers out there. And there was no good reason for it, except that most people (including many medical professionals) still do not know anything about central sensitization.
So I, and my blog, and my future potential physical therapy practice, are hopefully going to be doing something about that.
Please let me know if you have any questions, or any feedback on what sorts of things would be helpful in the future! I do take requests!
