So, What Is Chronic Pain?

Every time I tell someone that I work with people who have chronic pain, they want to know exactly what that means. I've been taking my time writing this blog post because it's complicated, but I think everyone should know about chronic pain whether they have it or not. Read on to find out what it is.

Just like stress, pain comes in two flavours, acute and chronic. To understand chronic pain, you first have to understand a bit about acute pain. Bear with me, because some of this is quite complex, but I'll try and break it down as best I can.

What is acute pain?

Acute pain is part of the body's alarm system. Imagine you step on a piece of Lego (I did this recently; I don't recommend it!). Touch or pressure receptors in your foot pick up the message that you've stepped on something that has the potential to cause damage to the body, and send a message up the nerves in your leg. The nerves in your leg are part of what we call the peripheral nervous system. That message then passes through a little junction box (called the dorsal horn, if you want to get technical) and enters your central nervous system - the nerves in your spinal cord and your brain. The message gets passed up to your brain, and your brain then makes a decision as to what to do about that message. If it interprets the message as painful (and of course it does - you've stepped on a Lego!) then that pain message gets sent back down to the nerves in your foot. You might then yelp a bit and pull your foot away, trying to stop the pain message - that's what I did, anyway! And all of that happens in the blink of an eye. Our bodies can be really cool sometimes.

 What is chronic pain?

In medical terms, chronic pain is any pain that has gone on for longer than six months. The people I work with might have had an operation, or a virus that caused pain, or might have broken a bone. But after six months, most if not all tissue damage that was caused will have healed, so that isn't the thing that's causing the pain any more.

People often look at scans as a good way of explaining their pain, but that doesn't really work. For one thing, we like to use scary words like "degenerative disc disease" and "osteoarthritis" when what we really mean is "age-related changes" or "normal wear and tear" - if you scan most people over the age of 30, you'll see some "degenerative changes" on a scan. But we know that not everyone over the age of 30 has chronic pain, so a scan like that doesn't tell us the whole story (and often contributes to people being worried that their "spine is crumbling," which can make you frightened to do anything for fear of making it worse).

For some people, their accident or injury has led to pain in different areas - for example, you might have started with back pain but then it spread to your legs, and now it's all over. This is an example of how your body can learn really quickly to amplify the messages that it keeps receiving. If it gets more messages that it interprets as pain messages, it will send more pain messages, and so on.

Some people didn't have an accident or injury - their pain just started one day, possibly after a period of stress or sometimes just at random. That's an indicator of how scary and wonderful our bodies can be - when they work well they're fab, but when they malfunction they can do so seemingly at random and it's genuinely nobody's fault.

Okay, but doesn't that mean that the pain's all in your head?

Absolutely not. I want to be really, really clear about that one. CHRONIC PAIN IS REAL. The pain people feel is real, it isn't "imaginary," and you can't just will it away by focusing on something else, or having loads of psychoanalysis. It's all to do with your nervous system.

You know how we talked about acute pain earlier, and about how the brain interprets messages as painful? Well, after an injury or illness, for some people that response system doesn't switch off. It keeps sending messages to the brain, and the brain keeps interpreting them as pain. We know that there's no damage or danger, that the Lego piece has been removed or that the operation was technically successful. But the brain and the nervous system don't know that, and they keep trying to protect you from a dangerous situation that doesn't exist. That's also true if your pain just started randomly - it's about your nervous system, not about your bones or muscles. That in a nutshell is chronic pain, and it explains why we can't just stop the pain - we can't remove the 'damaged bit' because there is no damaged bit, it's the person's nervous system that has gone wrong. And we can't take your nervous system out and give you a new one, unfortunately.

Pain is an opinion

There is a quote I like to use to explain a bit of this. It's from a scientist called V.S. Ramachandran, and in it he's talking about phantom limb pain.

"Pain is an opinion on the organism’s state of health rather than a mere reflective response to an injury. There is no direct hotline from pain receptors to ‘pain centers’ in the brain. There is so much interaction between different brain centers, like those concerned with vision and touch, that even the mere visual appearance of an opening fist can actually feed all the way back into the patient’s motor and touch pathways, allowing him to feel the fist opening, thereby killing an illusory pain in a nonexistent hand."
Quote from Phantoms in the Brain, by VS Ramachandran and Sandra Blakeslee)

So what does that mean? Well, you might have heard of phantom limb pain, where someone has their leg or arm amputated but can still feel pain in that limb, even though it isn't there any more. The reason for that is that even though you've removed the limb, you haven't removed the part of the brain that is responsible for being aware of that limb - remember, the brain is part of your nervous system. And whilst that part can change and fade with time, it can also become sensitive and worked up and interpret signals as pain where there is no limb at all. That can actually be handy in some ways, because it means that you can use mirrors to get a person with a missing limb to mimic an action with the limb that's still there (in the above example, opening a fist) and the body may reduce or stop the pain that's being felt. Therefore, pain is an opinion from the body taking into account lots of different factors, not a simple way of getting from A to B.

I hope that helps people to understand a bit of what I do, and why chronic pain is so important. Ultimately, if you don't have chronic pain it can be hard to understand, but it's useful to know that it exists so that if you ever develop it, you know what's going on. Next time, I'm going to talk a bit about how to manage chronic pain. If you've got any specific questions, let me know in the comments.