Today we’re picking back up where we last left in our journey to better understand the experience of pain.

If you haven’t, I strongly recommend you go and read part 1 so you have a good understanding where we are in this analysis and how we got here. I’ve also been made aware that there are some good memes there and you don’t want to miss out on memes, right?

Briefly summarising, in the first part we finished by understanding that the build up of evidence has showed that the brain and certain areas of it are necessary for the processes responsible for the pain experience, but not enough for it. We also looked at the reasonable argument put forward by Manzotti (2016) that in all known cases of pain, together with a brain, a body, stimuli, environment, past and future behaviour and social interactions were also present.

As they are always present, perhaps the environment, social interactions, past and future behaviours together with our perceptions of them, as well as the different stimuli arising from these different factors also have role to play in pain.

This same hypothesis crossed the mind of pain scientists from the 1980s onwards, who started describing the first psychologically and sociologically-informed pain theories and models (Stilwell and Harman, 2018). Among these, one of the most influential as the Mature Organism Model, proposed by the absolute mad lad Louis Gifford (1998). I guarantee it is out of respect that I attribute such a prefix to Gifford, so revolutionary that he was. Gifford started his career as a zoologist, later coming to physiotherapy (Hunt, 2014) but bringing his previously acquired knowledge with him – I’ll explore the relevance of this below.

This model basically states that there are stimuli from the environment or the bodily tissues that are received by neurons and sent into the brain. However, in contrast to previous models the brain is now more that a passive spectator. It will scrutinise the stimulus and then send a response or output based on said scrutiny having our body change something in the environment or something in itself, or if it feels a certain level of threat to its existence, the output will be pain.

So now we have signals going up as well as signals down, but where does the environment, past experiences, social interactions and all that come into this?

The scrutiny I mentioned before will be made taking into consideration a lot of information. Our brain, through conscious and unconscious thought processes, will consider other stimuli being received from the environment and the tissues, telling where we are right now, what’s happening around us and what the current state of our body is. It will consider our past experiences with similar stimuli, similar environment and what were the outcomes at that time. It will consider the beliefs we have about our body, how it works, our personal and social identity and what meanings we attribute to all of these. And of course it will try to make predictions about how the stimuli will affect us in the near and distant future, based on all the information it just processed. Depending on all this information, the level of threat to not just the body and its tissues, but also to our identity, social position and beliefs, will be calculated and if there is enough evidence towards threat our body will sound the alarm – pain.

With this conceptualization we begin looking at pain as a biopsychosocial phenomenon, which was a follow up from the push for a biopsychosocial healthcare model, created by Engel throughout his works from 1960 and 1977 (Stilwell and Harman, 2018). This model tried to progress the biomedical model of the time through the incorporation of the all the biological, psychological and social aspects of health, considering the relationship of the patient with their social and healthcare contexts (Stilwell and Harman, 2018).

You might by now be feeling some scepticism towards what I’m saying. “Thoughts and meanings and beliefs and consciousness. Mate, if I bang my toe, I’ve injured my body and that’s why it hurts.”True, but that’s an incomplete picture as we explored in Part 1. Just be patient and it will all make sense.

We, both as a society and healthcare systems, are still greatly under the influence of the Cartesian dualistic conceptualization of body and pain, and the biomedical model of healthcare. Considering this, I need to make a very important point clear: what I’m saying does not in any way mean that your pain is in your head. It does not have to be a binary phenomena and it isn’t.

Just to show how weird we humans are, there is research that showed that when people were made to experience pain when opening a small, rectangular blue box in a video game by moving a joystick to the left their body started associating opening a box with pain. This resulted in the subjects of that study started to present with the same fear responses and bodily preparation to pain – avoidance, protective and guarding behaviours and even changes in the responses of the brain and nervous system – with the right  joystick movement that involved opening a different boxes in the video game (Meulders, Vandael and Vlaeyen, 2016). You might say that this was a result of those people being trained to expect pain whenever they moved the joystick. However they did not present those fear responses when moving the joystick to close similar boxes in the video game – indicating that the physiological response was dependent on the meaning of the task being performed, even if physically the same movements are being performed.

We still don’t fully understand why this happens, but one of the hypothesis is that the main biological function of pain is to warn organisms of impending or actual body threat and motivate them to act towards stopping or avoiding that threat at present, as well as learning to avoid it in the future(Meulders, Vandael and Vlaeyen, 2016; Meulders, 2019). Thus we can see the link between our thoughts, beliefs and attributed meanings to the more physical functions – our thoughts and beliefs will shape our actions. If we think/believe a part of our body is damaged we will start acting in ways that try to protect that body part, consciously and unconsciously, usually through behaviours such as bracing or guarding. The issue is that these behaviours can actually increase tissue loading, perpetuating pain, in turn making you more worried because your pain is still there or is getting worse, which in turn makes you brace and guard more (Caneiro, Bunzli, O’Sullivan 2021). A lovely snowball of pain and worry.

The body and the mind are so inseparable that some studies have found that in people without musculoskeletal pain (pain relating to the muscles, bones, ligaments and cartilage) negative beliefs about pain predict the incidence of future disabling pain while in people with acute musculoskeletal pain, negative beliefs about their pain predicts how it will disable them over time much better than any assessment of their body tissues or structures (Caneiro, Bunzli, O’Sullivan 2021).

If you think your body is threatened due to damage or potential damage – you tell your body a threat exists and it responds to that potential threat. If constantly you feel stressed, sad or anxious – you tell your body a threat exists and it responds to that potential threat. If you feel like your current work, family situation or circle of friends is going to be threatened or you’ll lose them in some way – you tell your body a threat exists and it responds to that potential threat. In a way, it almost becomes a self-fulfilling prophecy: you think you’re not well – physically, mentally and socially – and due to this belief you will not feel well. Weird, I know.

By recognising the interplay between all these biological, psychological and social factors, we reach the current definition of pain used by the International association of pain: An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage (IASP, 2020; Raja et al, 2020). I point your attention mainly to that last part – “…or resembling that associated with, actual or potential tissue damage.” By definition, tissue damage is not a necessary part of the experience of pain.

So, now we have a definition and we understand it is quite complex. What does that mean to you?

If you are member of the general public and developed or are experiencing pain, even if it is quite intense and has been lasting for a long time, it doesn’t meant it is because you have a serious injury or damage to your body. If your pain didn’t start with physical trauma, it is most likely that the opposite is the case – no relevant changes are present in your tissues (Lewis and O’Sullivan, 2018). Even in the cases of trauma, you can still have pain long after your tissues have completely healed – your body is just being over protective.

All of this means that if you go to see a physiotherapist or any healthcare professional for your pain, they still need to rule out a serious pathology or injury, which mostly can be done through you telling them the story of your pain and how it presents. However together with this also expect them to ask you:

• What you think is happening?
• What you think is causing this pain?
• How do you respond to this pain?
• Have you started avoiding doing things because of your pain?
• What do you want to achieve?
• What are your expectations for this pain?

These might seem like weird questions for a healthcare professional to ask a service user but you now know, through reading this far, that these beliefs will affect both what you feel and how you will progress. Together with these, you will also be asked about other biopsychosocial factors that we know can influence pain, such as your activity levels, sleep, psychological health and your lifestyle in general (Caneiro et al, 2020; Caneiro et al, 2019)  . This is the sign of a health professional that has kept up with the evidence and current guidelines, and cares about you as a person, not a body part (Caneiro et al, 2019; Lin et al, 2020; Lewis and O’Sullivan, 2018).

For clinicians, this means that when addressing non-traumatic pain, after ruling out serious pathology, you need to have an individualized patient centred approached, taking into consideration their needs and valued activities, educating about their pathology and prognosis, overcoming unhelpful beliefs and myths, participating in joint decision making, planning and guiding towards management strategies and improving lifestyle factors such as sleep, stress management and social interactions. And please, don’t treat them as machines with damaged parts, they’re not cars.

I hope you feel you’ve learned something by now and hopefully I’ve changed your perspective about pain and that it is not simply a signal coming from tissue injury. As I repeatedly mentioned, in our society is still mostly dominated by a mechanical view of pain which as lead to mistreating and failing people with pain. I can only apologise if this has happened to you. I can assure we are trying to learn more about this complex phenomenon and how to manage it.

I also suggest we might need to change our perspective of pain as a society. This is purely a personal opinion and I would love for you to challenge, as it is prone to change through being shown perspective and facts I’m not aware of at the present. I think that in the future, the understanding and management of pain will need to take into account individual’s perceptions of suffering-related experiences and its role in day to day live and society. Is it a realistic expectation to wish for a suffering, and therefore pain-free life? Or should this experience and all its cognitive and physical expressions be better integrated into our day to day? Pain developed as survival mechanism. Considering this, is there value in suffering?

Do you agree with me? Are you still confused about any of this? Please let me know through a comment in any of the social media platforms I use!

References:

Caneiro, J. P., Bunzli, S. and O’Sullivan, P. 2021. Beliefs about the body and pain: the critical role in musculoskeletal pain management. Brazilian Journal of Physical Therapy. Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia, 25(1), pp. 17–29. doi: 10.1016/j.bjpt.2020.06.003.

Caneiro, J. P., Roos, E. M., Barton, C. J., et al. 2020. Infographic. Roadmap to managing a person with musculoskeletal pain irrespective of body region’, British Journal of Sports Medicine, 54(9), pp. 554–555. doi: 10.1136/bjsports-2019-101681.

Caneiro, J. P., Roos, R. M., Barton, C. J., et al. 2019. It is time to move beyond a ‘body region silos’ to manage musculoskeletal pain: Five actions to change clinical practice, British Journal of Sports Medicine, 54(8), pp. 438–439. doi: 10.1136/bjsports-2018-100488.

Gifford, L. 1998. Pain, the tissues and the nervous system: A conceptual model. Physiotherapy, 84(1), 27–36. https://doi.org/10.1016/S0031-9406(05)65900-7.

Hunt, L. 2014. Pain pioneer Louis Gifford dies from cancer. Chartered Society of Physiotherapy : Frontline – The Physiotherapy Magazine for the CSP members. [online] Available at: < https://www.csp.org.uk/frontline/article/pain-pioneer-louis-gifford-dies-cancer#:~:text=It%20is%20with%20great%20sadness,he%20died%20on%209%20February >

International Association for the Study of Pain, 2020. IASP Announces Revised Definition of Pain. Washington. [Online] Available at: < https://www.iasp-pain.org/PublicationsNews/NewsDetail.aspx?ItemNumber=10475 >

Lewis, J. and Sullivan, P. O. 2018. Is it time to reframe how we care for people with non-traumatic musculoskeletal pain ? Br J Sports Med , pp. 1–2. doi: 10.1136/bjsports-2018-099198.

Lin, I., Wiles, L., Waller, R., et al. 2020. What does best practice care for musculoskeletal pain look like? Eleven consistent recommendations from high-quality clinical practice guidelines: Systematic review’, British Journal of Sports Medicine, 54(2), pp. 79–86. doi: 10.1136/bjsports-2018-099878.

Manzotti, R. 2016. No evidence that pain is painful neural process. Animal Sentience, 3(11).

Meulders, A. 2019. From fear of movement-related pain and avoidance to chronic pain disability: a state-of-the-art review’, Current Opinion in Behavioral Sciences. Elsevier Ltd, 26, pp. 130–136. doi: 10.1016/j.cobeha.2018.12.007.

Meulders, A., Vandael, K. and Vlaeyen, J. W. S. 2016. Generalization of Pain-Related Fear Based on Conceptual Knowledge, Behavior Therapy. Elsevier B.V., 48(3), pp. 295–310. doi: 10.1016/j.beth.2016.11.014.

Raja, S. N. et al. 2020. The revised International Association for the Study of Pain definition of pain: concepts, challenges, and compromises. Pain, 161(9), pp. 1976–1982. doi: 10.1097/j.pain.0000000000001939.

Stilwell, P., Harman, K. 2018. An enactive approach to pain: beyond the biopsychosocial model. Phenomenology and the Cognitive Siences,[e-journal] 18, pp.637-655. Available through: https://doi.org/10.1007/s11097-019-09624-7

I’m going to discuss one of the more complex and debatable subjects among health care professionals, pain.

Essentially I’m setting myself up to have a very rocky start to this site. However, considering the main reason people see a physiotherapist for is pain somewhere in their body, particularly in my area of work -the musculoskeletal system (fancy jargon for things relating to bone, cartilage, muscle, tendons and ligaments) – as well being the main cause of disability globally (Hurwitz et al, 2018), I feel it is a subject we need to try to at least reach a common ground on from the start.

So what is pain? This thing that basically everyone has experienced one time or another in their life, but when we try putting it into words, it doesn’t really come easy. I say mostly because there are actually some people who are born without the ability to experience pain – keep that in mind, as it will come up later.

We can mostly agree pain is unpleasant, although there are some people who appear to actually find it quite enjoyable, usually named masochists (if you don’t know what that means, type it in, Google’s your friend as Jay Z said – just make sure your grandma isn’t nearby). We can agree we feel pain somewhere in our body, although some people sometimes also experience in limbs that they are missing, an experience known as ‘phantom limb pain’.

• Curiosity: phantom limb pain termed coined by American Civil War military battlefield surgeon Silas Weir Mitchell (Collins et al, 2018).

Sorry, it doesn’t seem like I’m making this any easier for us. It will be philosophically lacking if we start talking about a subject without having defined well what we’re actually talking about, so my suggestion is that we start by discussing briefly how our understanding and definition of pain evolved throughout the ages.

The first attempts at explaining pain were mainly mystical in nature (Stillwell and Harman, 2018).  However in the seventeenth century, as a direct result from the renascence and its focus on leaving behind mystical and religious explanations to the world, came the man who doubted everything, René Descartes. He said “I’m going to create an idea so influential and controversial, that it will distort our understanding of pain and the relationship between the human body and mind for generations to come”.  As he said, he did, and Cartesian Dualism was born. This is a theory that argued the existence of a dualism of body and mind, the two being distinct: the mind being immaterial and the body being material (Stillwell and Harman, 2018; Russel 2004). Under this theory Monseigneur Descartes explained that when a person received a particular stimulus such as suffering a cut or being burnt, this would cause the tugging of physical tubes that travelled to the brain, where they would cause the release of animal spirits that caused pain – which he deemed to be directly proportional to the amount of tissue damage – and a consequent response of moving the affected body part away from the stimulus (Stillwell and Harman, 2018).

When you first hear about this theory, you may think it is outdated, if not also ridiculous. I mean, animal spirits being released in the brain.

It took two centuries for the concept of animal spirits to stop being used. Despite this dualistic theory of body and mind, and linear relationship between something called noxious (potentially nocive) stimulus and pain still remains the most prevalent one throughout most of society (Stillwell and Harman, 2018), although many sectors of healthcare are making a significant effort to change this.

• Curiosity: Noxious stimuli are potentially dangerous stimuli captured by specialized peripheral receptors that fall into one of three categories: mechanical (for e.g. pressure, growth, incision), thermal (hot or cold) and chemical (reduced oxygenation, infection). These receptors capture stimulus fitting these categories  and convey them in the form of electrical nerve signals. These stimulus are not harmful per se, however when the these signal reach a certain intensity they are perceived by the body as being potentially dangerous (Potter, 2007). Think about how both light touch and pinching, or warm and boiling water, belong to the same class of stimulus, but at different intensities, and as such being perceived differently in normal physiological function.

The problem with this type of linear relationship was that it was not able to provide an explanation for cases where pain was present without a clear physical cause, like the previously mentioned phantom limb pain or most cases of non-traumatic lower back (Lim et al, 2018; Lewis and Sullivan, 2018). In an attempt to improve on this, in the 1960’s scientists focused more on the possibility of the brain having an active role in pain modulation, as opposed to its so far attributed role of a simple passive receiver (Stillwell and Harman, 2018).

It was at this time when the well known and still vastly utilised gate control theory of pain was presented by Melzack and Wall. In simple terms, the argued that there was some type of neurophysiological “gate” in the spinal cord that could be closed by non-noxious stimuli, resulting in actually nociceptive inputs to be blocked from ascending into the brain (Stillwell and Harman, 2018).

Melzak and Wall are also the first ones to propose that the brain could stop nociceptive stimulus through a process called Descending Inhibition. Despite we now knowing that gate theory is incorrect, the idea that pain could be as much a top-down as a bottom –up process was a big breakthrough in pain research and continues to be build upon by modern research (Stillwell and Harman, 2018).

However, as often occurs with scientific breakthroughs, they lead to inaccurate extrapolations. A couple of decades after Melzack and Wall we start seeing an emergence of brain-centric theories of pain. The most influential of these was actually proposed again by Melzack: the neuromatrix theory(Stillwell and Harman, 2018). This theory states that sensory, affective and cognitive-related brain regions provide inputs to a widely distributed neural network in the brain, the body-self neuromatrix, which result in outputs to other brain areas that subsequently produce the perception of pain, pain related action programmes (quickly moving your foot away from the Lego piece you just stepped on), and stress regulation programs (immune response) (Stillwell and Harman, 2018).

By now you may be thinking – “But what is the problem of the brain having a central role in pain? I thought that’s were all our experiences come from. It could also explain those cases in which people have pain without structural causes or on missing body parts!”.

Well, your reasoning sounds logical. However, consider the following: if the brain is the source of pain, then when we experience pain, the previously mentioned areas of the pain should be active, and when we are not experiencing pain, those areas will be inactive. The empirical conclusion of this would be that if we monitor those areas, let’s say using some type of electrodes or even the fancier functional MRI (fMRI) while someone is having a pain experience, then we could confirm if those areas are indeed behind the experience of pain. Salomons and their team tried exactly that and published the results in the JAMA Neurology journal (Salomons, 2016), but the results were quite surprising – they were able to locate and record the theorized pain-related activity of certain brain areas, but, this same brain centers displayed the same pain-related signatures were present and recorded in people who had congenital insensitivity to pain. People who literally can’t feel pain – I told you before that detail was going to be important.

So how can people who can’t experience pain have the same pain related areas and signatures in their brain? Is pain not in the brain? Where is it and how does it work? It sounds like we still have as many questions as when we started, if not even more.

Maybe because we’re looking at pain as a simple cause-effect relationship and it is actually more complex than that. As stated by Manzotti (2016), in all known cases of pain a brain is present, but also are bodies,  stimuli, tissue changes, behaviours of that body and brain, social interactions between those bodies and brains, and an environment in which all those exist.

If you want to find what this means for our understanding of pain, don’t miss the second part of this explanation!

References:

Collins, K. L. et al. 2018, ‘A review of current theories and treatments for phantom limb pain’, Journal of Clinical Investigation, 128(6), pp. 2168–2176. doi: 10.1172/JCI94003

Hurwitz, E.L., Randhawa, K., Yu, H., Côté, P., Haldeman, S. 2018, The Global Spine Care Initiative: a summary of the global burden of low back and neck pain studies. European Spine Journal, [e-journal]27, pp.796-801. Available through: https://link.springer.com/article/10.1007/s00586-017-5432-9 [Accessed 9 January 2021].

Lewis, J. and Sullivan, P. O. 2018 ‘Is it time to reframe how we care for people with non-traumatic musculoskeletal pain ?’BRr J Sports Med 0(0),  pp. 1–2. doi: 10.1136/bjsports-2018-099198.

Lim, Y. Z. et al. 2019 ‘People with low back pain want clear, consistent and personalised information on prognosis, treatment options and self-management strategies: a systematic review’, Journal of Physiotherapy. Elsevier B.V., 65(3), pp. 124–135. doi: 10.1016/j.jphys.2019.05.010.

Potter, J. F.,Titman, H.M. 2007. Persistent Pain. In: R.J. Ham, P.D. Sloane, G.A. Warsaw, M.A. Bernard, E. Flaherty, eds. 2007 Primary Care Geriatrics. Mosby, pp.350-360

Russel, B. 2004. History of Western Philosophy. New York: Routledge Classics

Salomons, T. V., Iannetti, G. D., Liang, M., &Wood, J. N. 2016. The Bpain matrix^ in pain-free individuals. JAMA Neurology, 73, 4–5. https://doi.org/10.1001/jamaneurol.2016.0653.

Stilwell, P., Harman, K. 2018. An enactive approach to pain: beyond the biopsychosocial model. Phenomenology and the Cognitive Siences,[e-journal] 18, pp.637-655. Available through: https://doi.org/10.1007/s11097-019-09624-7