July 17, 2013

Moseley: Why Things Hurt

I often send this link to clients (and friends) who are experiencing chronic, apparently disproportionate pain. Partly I'm just stowing it here so I'll remember where it is.

A big obstacle in dealing with this kind of pain is that there's a widespread, fundamental misunderstanding about what pain is, and how it is created. It is not a direct perception of tissue damage. It's an alarm that's set off by one part of the brain (unconsciously) in order to get the full attention of the conscious part of the brain. How loud that alarm will be depends on a number of things, but it boils down to a unconscious assessment. The nervous system makes a preliminary judgement: just how bad is this thing that just happened? And it sends off a correspondingly loud alarm.

Here's the problem: it's really not very good at this. It takes some input, does a lightning quick check of fearsome things that can happen that might match that input, and if it finds something really scary, it blasts the siren. Better safe than sorry, is its motto. And remember, this happens before the conscious brain has any input. You don't get a chance to interrogate the nervous system. You don't get to say, "hmm, are these the sort of signals I might expect after overusing my back muscles, or are these the sort of signals I'd get from a spinal disk slipping out of place?" The first thing you -- meaning your conscious brain -- know, is a blast of intense and terrifying pain. It's completely real, as real as pain ever gets. But it may not mean there's anything particularly wrong.

Very unfortunately, though, the pain itself gets added to the database. And the next time your back muscles twinge, one of the fearsome things that show up in the unconscious brain's quick search is that this thing can REALLY hurt! Better intensify that alarm! Send up an even louder alarm than last time!

At this point, we're well on your way to what we commonly, and erroneously, call "a bad back." What we actually have is glitchy nervous system. Since there's nothing particularly wrong with the back, nothing we do to it is actually going to help very much (unless we inadvertently manage to reset the nervous system's responses.) If we don't understand that the nervous system can trip over itself like this, we're likely to undertake all kinds of things -- some of them drastic, such as fusing vertebrae -- in order to fix something that is not broken.


  1. Eh, "part of the brain" is sloppy: "subsystem of the nervous system" would be better. But that's unendurably clunky English.

  2. This is an appealingly simply way of thinking about chronic pain and disability, but see also http://www.bodyinmind.org/fear-avoidance-model-evidence/, and Lorimer's reconsideration, http://cdn.bodyinmind.org/wp-content/uploads/Fear-avoidance-model.pdf

  3. Wow, it's amazing what our brain does that we aren't even remotely aware of. Nice way to think about chronic pain - but makes it difficult to know how to listen to your body properly!

  4. Yes, exactly, Anna! I used to be one of those people who urged clients "to listen to their bodies," but it's actually a lot more complicated than that. Our "bodies" -- by which we mean our sensations, which are formulated by the nervous system -- actually lie all the time, and taking them at face value can be disastrous. Mindfulness can play a big part of recovering from persistent pain, but part of it is realizing that it's "not necessarily so" (as Suzuki Roshi always said.)