I think it is initially worth exploring the physiology of pain – what is it, how does it work, what is the point of it? This will give us the context to then understand chronic pain better.
f you have time to watch this excellent video from Lorimer Moseley, one of the (if not THE) leading pain scientists in the world, it will help a lot – and summarise a lot of what I have to say about the physiology of pain much better than I am about to. I’ll flag where you can jump in to skip the first part of this blog to avoid overlap of information.
https://www.youtube.com/watch?v=gwd-wLdIHjs
However, if videos aren’t your thing but reading is, hopefully I’ve done well enough to explain in words below.
First of all, it’s worth stating that pain is ALWAYS “in the brain” – the brain is what “generates” pain, or perhaps more accurately, the brain is what creates the unpleasant experience we call pain. I hope this is useful for those who may suffer from chronic pain and may have felt in the past that people thought that they were making things up, or that it was “all in their head”. All pain is in our heads! Even the “usual” pain. This does not make it fake or imaginary – it makes it completely real.
The brain is constantly receiving messages from our entire body. It then interprets these messages – it weighs up risk, past experiences, emotions, memories, strength of stimulus – comes to a conclusion as to what it thinks is going on, and then we get the resulting sensation (or lack thereof).
When this system is working as it should and is accurately depicting what is going on, we get an accurate sensory experience. For example, if my cat were to brush up against my leg my brain would interpret the stimulus (something soft rubbing on my leg, memories of my cat doing this all the time, happy emotions associated with this) and I would, before even having to look down, know that this is my cat rubbing against my leg. Or perhaps a less happy situation – I really annoy my grandmother who is knitting, and she stabs me in the thigh with her knitting needle. So in this context the brain would interpret the stimulus (something sharp piercing my skin, no past experience of anything similar, negative emotions based on someone I love doing something quite shocking and threatening) and I would, quite rightly, experience a presumably large amount of pain at the point where the knitting needle had been jammed into my thigh.
When this system is not working quite as intended, we get an inaccurate sensory experience. For example, the next time I visit my grandmother I am being much less annoying, she is not holding any knitting needles, and she reaches out to pat my thigh. My brain interprets this (location of sensory input is the same as with the knitting needle incident, memories of my grandmother stabbing the knitting needle into the thigh, highly negative emotions associated with this) and I feel an intense stabbing pain. Now you could argue that perhaps this is fair enough – the first time it happens. But say this continues – every time something so much as brushes up against my thigh I feel pain, and this spirals to the point where my thigh is always painful even without contact with anything, and that any contact (even my bed covers) result in high levels of pain. This is no longer an accurate representation of what is going on – the brain has become too focused on that area of my thigh, any sensation is now triggering an excessive pain response from the brain, and all in all it’s quite the frustrating situation to be in.
There’s several things going on here which help to create this melting pot of mess – central sensitisation, peripheral sensitisation, and psychological factors (because it’s rather a distressing situation to be in!).
Central sensitisation means that the “central nervous system” – the brain and spinal cord, but we’re thinking specifically about the brain – is hyper-aware of this area of my body. There’s a larger portion of the sensory cortex of the brain that is now dedicated to my thigh, meaning any sensory input activates a larger portion of my sensory cortex. This has developed in a negative sense – it is always at the ready, expecting threatening stimuli – meaning that even small and usually innocuous stimuli now appear much more threatening and intense.
Peripheral sensitisation means that the peripheral system – the synapses locally which pass messages along – are also more active. They have developed an increased response to stimuli (more messages are being sent and faster). And you can imagine if there is an increased peripheral sensitivity, so more messages are being sent much more quickly and with less input, paired with an increased central sensitivity, so these messages are appearing louder to the brain, and much more threatening – the increase in pain response is compounded.
We also know that our emotions, expectations, stress levels etc all play a part too – the more we are expecting something to be painful, the more pain we generally feel. When we are tired and stressed, stimuli appear more threatening to us. Similar to how if we’ve had little sleep and are stressed, small things irritate us which normally wouldn’t – small stimuli which are normally not problematic, become problematic.
If you’ve watched the video – feel free to jump in here:
Approaching chronic pain rehabilitation is best done in a team setting – where your GP, perhaps a pain specialist, for certain a pain psychologist, and physiotherapist work together to get the best results.
From a physiotherapy perspective, we work on trying to reduce the sensitisation (I refer to this as winding down the volume on the very wound up pain system) and therefore decrease the pain, while increasing the activity/exercise that someone is able to manage. Often this looks like nudging into pain – where you are able to do a certain level of activity with an “acceptable” level of pain which doesn’t linger. We then allow this to settle fully before “nudging” again – and slowly over time we make incremental changes. Slightly more activity with slightly less pain, and repeat that process. We call this graduated exposure.
I tend to tell people that this is a little bit of art work – there’s obviously the scientific principles that underlie it, but everyone is different and the irritability (reaction to progression) can vary drastically. This means it’s educated guesswork, while erring on the side of caution initially, until we figure out your individual response and rate of progression.
In all honesty this can be quite the frustrating process. Sometimes we might overshoot and you can have a flare, other times we might undershoot, and overall the progress can seem very slow. To do this properly it takes time as the progressions need to be very slow and small in order to avoid the opposite effect – increasing the sensitivity and winding the volume back up. To stay engaged it’s important to have your end goal in mind, but also to have little steps/goals along the way that you can celebrate – because it’s all about the small wins that eventually get you to the big win.
And finally – I think it’s important that you gel with your physiotherapist. You’re going to be spending a lot of time with them! You need to get on to some extent, be able to share honestly about how you’re doing and feeling during the process, and be working with someone who you can envisage seeing on a regular basis for an extended period of time – frequency is up to you/your physio.
Useful online resources:
