Chronic Pain written on a cream background. Three cartoons show graphics representing pain with characters curled up surrounded by lightning bolts.

Understanding Pain Part 2: Chronic Pain

Hello again everyone. I hope you enjoyed learning all about pain in my last blog! That was just a basic overview of pain in general. This time I want to talk about chronic pain and central sensitisation. Hopefully this will give you a better understanding of what happens and why.

Before coming on this placement, I thought I knew a fair bit about chronic pain. However, it turns out there is so much more to learn. It is a very complex subject to get your head around and understand why your body is working in a certain way.

Chronic pain is something I have lived with for many years now. People all around me, including my friends and family haven’t really understood what life is like for me with my conditions. An example that springs to mind would be when I walk into something and bump my hip. For a lot of people that would just be a little pain and off they go. For me, oh my, I would be crying out in pain as if my hip was on fire!

So, let’s talk a little bit about that.

Central Sensitisation

When you start to experience chronic pain, you are probably always close to or in what we call the ‘alert zone’. This means that at any time you could have a sudden onset or increase in pain. Central sensitisation occurs because or body is constantly in this state of high reactivity. This then lowers our threshold for what causes pain. This then maintains pain even after an initial injury has healed.

There are 2 main characteristics of central sensitisation. Allodynia and hyperalgesia. Allodynia is when we experience pain with things that are not normally painful. So, you could experience pain from putting your toe on some grass. We as chronic pain patients will feel pain when we are not supposed to. A simple touch could prompt the brain to produce pain and discomfort. On the other side of that, hyperalgesia is when something that is painful becomes more painful that it should be. So, the example I gave at the beginning of this blog would fall into this category.

Don’t you just get the feeling that when things like that happen people just don’t understand? When you bump your knee, and it feels like it’s on fire. You’re grimacing and crying out in pain and people just think what is going on? People think we are making it up because it just does not happen to them.

Central sensitisation can lead to a heightening of all senses, not just touch. Chronic pain patients sometimes have sensitivity to light, sounds and odours. I’m sure some of you reading this can relate to that. It can also affect cognitive function. For me that means I have a terrible short-term memory. I also find it difficult to concentrate at times. Another thing that can happen with central sensitisation is ‘sick role’ kind of behaviours. So, when you find yourself experiencing post exertional malaise, this is why.

Central sensitisation involves specific changes to the nervous system. These changes happen in the dorsal horn of the spinal cord. This is basically your processing centre. Your excitatory and inhibitory neurons live here. And they are the neurons that take information to the brain. The neurons can either facilitate or inhibit pain. In chronic pain, they are more likely to facilitate it.


This is a good thing. All living organisms have the ability to adapt! Bioplasticity can be both good and bad. It is responsible for your systems becoming more protective. This means it can also make them less protective! Pain is about protecting you. To get back to a kind of ‘normal’, things need to be done gently. It can be hard work. You will need patience and persistence to get there. You need to learn how to find the line between doing enough to make systems adapt but not too much so as that they cause a flare up. Because the longer the nervous system has been protecting you, the better it is.

Learning to become less protective is just another skill to learn. Like learning to ride a bike. You can learn to move differently so as not to cause a flare up. The more you practise, the better you will become. Teach your body that if you do the thing, it will not crumble. Maybe start by doing part of the thing. Break it down into smaller chunks that are less painful. Then piece it together.


DIMS and SIMS can help you to understand what triggers your pain and how to manage it. DIMS are the Dangers In Me. SIMS are the Safety In Me. Dangers are anything that could be dangerous to your body tissues. This could be lifestyle, job, your happiness or day to day function. Anything that is a threat to who you are as a person. SIMS are anything that makes you stronger, better, healthier, more confident, sure and certain within yourself.

Mosely and Butler (2015) have identified 7 categories of DIMS and SIMS: things you hear, see, touch, taste or smell, things you do, things you say, things you think and believe, places you go, people in your life and things happening in your body. Some things in life can be both DIMS and SIMS. An example could be a hospital appointment. It could be a DIM because you are terrified of the outcome. It could be a SIM because you will finally get some answers. It all depends on context!

SIMS can help with elements of safety in your life. DIMS can add to the danger. So, your partner could either be supportive. Or your partner could tell you it’s all in your head. If your DIMS keep adding up, then you feel pain. But if your SIMS outweigh them, you will feel less or no pain.


So, basically, you have an internal protectometer. This can either dial your pain up or down. The thing with chronic pain is that it can start higher than it does in ‘normal’ people. Especially if you’ve had ongoing experiences of pain and danger in the past.

Your body has an alert zone too. Just thinking about whether you have a headache is enough to raise pain. With chronic pain, you may be close to or in this zone all the time. The addition of one DIM may be enough to push you up the protectometer.

A flare up means that you have moved well into the pain zone of your protectometer. It is rarely a sign of new tissue damage. If you try to push through a flare up your brain will probably make drastic attempts to protect you even more. You may get dizzy or throw up. Think about how much you want to do, how much it takes to hurt you. How much can you do before you really flare up? Set yourself a sort of base camp where you are safe from flare up. This will be your starting point.

To progress do a little more each week. Not much more, but just enough to sneak under your pain radar. Find activities and people who will help to flood your body with ‘happy hormones’. These will stop the danger messages from reaching your brain.

The End

Pain is often unpredictable. This is what makes us more frightened of it. Emotional pain can help us understand the process of pain. It may even help you to become less frightened. Grief is often referred to as pain. The pain of losing a loved one can be as debilitating as breaking your arm. Just think about that for a moment. Think about it in relation to your pain.

When pain persists, it feels like it’s ruining your life. It is difficult to see how it is serving any purpose. The context of pain is what is crucial.

When you start to understand pain more, respect it and don’t fear it, you will use the power of bioplasticity. The road to recovery will start. This will not be plain sailing. There will always be ups and downs. This is not a bad thing. This is your body adapting.

Further Reading

Central Sensitisation:

Pain Pathways:

The Explain Pain Handbook Protectometer by GL Moseley and DS Butler

Explain Pain by David Butler Lorimer Moseley

About the Author

Hi, I’m Zandra. I’m a second year Physiotherapy student currently studying at the University of Brighton. My interest in Physiotherapy grew during lockdown while I was looking after my Mum and seeing what a difference I was making to her wellbeing. I have lived experience of chronic pain and fatigue as I have been diagnosed with CFS, fibromyalgia and haemochromatosis. Through finding my own ways to cope, I feel like I have a lot to offer to people who find themselves in similar situations.

I live in Kent with my Dad and my brother. In my spare time I love to walk, read, watch cricket and trampoline!

So let me know what you think and feel free to get in touch via I Also have an Instagram account that I am working on @zandraphysio. Hope to hear from you soon 😊

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