If a rose thorn pricks your finger, how do you experience pain?
The rose thorn activates nociceptors in your skin and this produces signals that are transmitted along your nerves, to your spinal cord, which then transmits these signals to your brain. Your brain evaluates these signals to determine whether this is a painful experience for you.
That is, your brain is the part of you that tells you that you are experiencing pain in your finger.
Nociception does not mean that we will experience pain.
There is often a misunderstanding by doctors, therapists and patients that nociception is the same as pain – they think that your finger being pricked by the thorn tells you that you have pain.
But the rose thorn causes nociception, your brain determines whether this is painful.
This difference is important for them and you to know, as this helps explain why we experience pain and why pain rehabilitation works.
There are different types of nociceptors in your skin, soft tissues, joints, muscles, bones and organs. Nociceptors detect changes in pressure, temperature and chemical concentrations to warn us of danger and potential tissue damage. Once activated, they start sending nerve impulses (danger messages) along your nerves, via your spinal cord, to your brain.
The brain receives these nociception signals and assesses their significance by evaluating other information such as your memories and past experiences of pain, where you are, what you are doing, your beliefs and fears, what you are thinking and feeling, what you are expecting and what your other senses (like vision) are telling you.
Your brain then decides, based on all of the available evidence, that you have pain (=you are in danger) OR that you don’t have pain (=you are not in danger).
Your brain can adjust the amount of nociception
Your brain can turn down the nociception (danger) messages coming from your body (called descending inhibition) and it can turn them up (called descending facilitation). Therefore, a small amount of nociception can lead to high levels of pain and large amounts of nociception can be pain free.
Because of our brain’s involvement, the amount of danger information (nociception) coming from our body is often not closely associated with the amount of pain that we experience.
(You can’t have pain and not know it but you can have nociception and not know it).
So, we can’t use pain to accurately tell us what’s happening in our body. But rather, our pain is a warning of danger, which we can and need to evaluate.
An easy example that nociception does not always lead to pain – is walking. When we walk, we always activate some pressure nociceptors in our feet but this does not usually lead to pain unless we walk further than we are used to.
Also, try bending your finger back – you are activating nociceptors when you start to move your finger but it won’t cause pain until you reach the extreme positions or hold it in the same position for longer than your brain likes it.
Pain does not always mean that we have nociception, an injury or ongoing damage
Just to complicate our understanding, we know that we do not even need nociception to experience pain – phantom limb pain in an amputee is an extreme example where you can experience pain in a leg that is not there. That is, there is no nociception coming from the leg, but the pain is still real and feels like it is in the leg.
And we know that pain can occur without nociception in everyone – activating a certain memory by thinking about an injury can lead you to imagine and experience the same pain you had at the time of the injury.
So when you experience pain in your body (e.g. your knee), it does not mean that your knee is injured or damaged. There may be no injury or nociception present. The tissues have probably healed if the injury or surgery took place more than 6 or 12 weeks ago.
Be reassured, we believe that your pain is real. But think of the meaning of your pain as danger or a warning, not damage or injury. Further evaluation is needed to determine if there is an injury or damage that needs attention.
PAIN IS NOT MADE UP PAIN OR “ALL IN YOUR HEAD”.
The importance of recognising the difference between nociception and pain
So, it is important when assessing your pain that you recognise the difference between nociception (signalling possible tissue injury) and pain (signalling danger).
If you and your treaters don’t recognise this difference, you can remain focussed on the painful body part, thinking that something must be wrong with it. You may keep looking endlessly for tissue injuries that have healed and receive treatments for the body that are unhelpful. Unfortunately, believing that a body part remains injured or damaged contributes to long term pain and makes it hard to rehabilitate.
Pain rehabilitation holistically treats all of you, by addressing all of the factors that can contribute to nociception and pain.
Watch the video below on Nociception and Pain and then improve your knowledge with the quiz
(if your internet connection is slow, lower the quality of the video by clicking the wheel at the bottom of the video)
