Is Pain an Illusion?

25th January 2012
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Illusion: ‘a deceptive appearance, a false idea or impression’.

Lorimer Moseley, who is one of the biggest names in the Pain Science world at the moment, raised an important argument when he recently spoke at TEDx. He explained nicely ‘why things hurt’ and proposed that pain is, in fact, an illusion. A video of Lorimer’s full talk is below and is well work a watch.

Structural-pathology models of pain, which suppose pain is an accurate reflection of the state of the tissues, are commonly accepted amongst the general public (as well as many non pain-science literate clinicians). However, on closer inspection, the biology of pain is less straightforward, even when it appears to be.

Louis Gifford, in his 1998 mature organism model [1] described pain as a ‘perceptual component of the stress response’ with a primary purpose to ‘alter our behaviour in order to enhance the processes of recovery and chances of survival’. Careful choice of the word ‘perception’ here implies a process of awareness and/or interpretation via the senses. Pain experts such as Louis Gifford have recognised that pain may not be representative of the state of play of tissues, and described it in such terms, for well over a decade.

More recently, Lorimer Mosley built on much of Louis Gifford’s earlier musings with his’ paper: ‘reconceptualising pain according to modern pain science’ [2].

In this paper he discusses 4 main issues relating to pain:

1) Pain does not provide a measure of the state of the tissues

2) Pain is modulated by many factors from across somatic, psychological and social domains

3) The relationship between pain and the state of the tissues becomes less predictable as pain persists

4) Pain can be conceptualised as a conscious correlate of the implicit perception that tissue is in danger.

The human brain is highly sophisticated, and it is this level of sophistication, which actually allows us to succumb to illusions. The brain fills in missing information and/or ‘bends the truth’ to provide a favourable or meaningful outcome based on the information it receives. The fact that the brain selects meaningful outcomes or interpretations for a given situation is demonstrated nicely by visual illusions such as the one below. When asked which of the 2 solid black lines is the longer, the majority of people will answer the one on the right, but they are in fact the same length.

Pain Science has shown us that pain is something that exists in the brain 100% off the time, therefore the perception that we have ‘pain’ in our arm/ leg/ back etc. could logically be described as an illusion. Again the brain manipulates information to provide us with favourable or logical information when it provides an anatomical reference for our pain, giving us the experience of pain in our arm/leg/back etc.

If we consider the first few moments of an acute injury we see that the CNS/brain receives information about the situation or environment via the sensory organs and about the state of its tissues via sensory neural (eg nociceptor) and humoral (circulatory) pathways.

The brain scrutinises this information in order to provide an appropriate response. This process may or may not result in the perception of pain depending on the precise situation and context or meaning. For example, in some instances part of the brain response/ output may be to prevent nociceptive messages from impinging on consciousness [3]. This may be the case for an injured person whose life is under severe threat (for example a soldier on the battlefield as opposed to a footballer on the pitch) and could mean that they actually feel no pain at all in response to an injury to their body tissues.

Research has shown that attention (to or away from pain) and anxiety, can both modulate the amount of pain we experience [4]. The common denominator in terms of the affects of anxiety and attention and expectation, seems to be the evaluative context, or meaning of the pain. I see loads of marathon runners in my clinic who develop niggles in the last few days or weeks before their race as attention shifts to ‘how ready their legs are’.

Pain is a state of implicit threat

Persistent pain is known to represent altered information processing throughout the system, and is not solely a result of damaged and degenerating tissues. Often there will be no detectable tissue pathology but misleading pain symptoms suggestive of it. It is the ‘implicit perception of threat’ that determines the output of pain, not the state of the tissues, nor any actual threat to them.

Super-recent advances in pain research and treatment are now reflecting this understanding by looking at manipulating sensory information. Relatively simple manipulations of multisensory cortical representation provided by; crossing the arms [5] by self- touch [6] or by distorting the visual appearance of the painful body part [7] [8] can all have analgesic effects.

Our modern understanding of pain has also provided considerable light on treatment mechanisms or ‘how the things we’ve been doing to help people in pain have actually helped them’. It would seem that ‘modulation of the implicit threat of danger to the body’s tissues’ is the key ingredient for reducing pain. This could be provided by any number of different treatments, given that the state of implicit threat in question may result from information spanning biological, psychological and sociological domains.

Factors influencing one individual’s pain experience may vary considerably from the next and the right context or meaning for the individual patient is key.

The patients understanding of the problem seems key also. For example if they have interpreted their symptoms, or had them explained by a clinician based on mechanical paradigms’ for example ‘misalignment of joints’ or nerve’s being ‘trapped’ then a treatment that the patent believes might address mechanical issues such as manual therapies may be primed to reduce the perception of threat and thus have favourable outcomes.

In support of this notion, treatment expectancy has repeatedly been shown to influence outcomes. For example, Kalauokalani and colleagues [9] found that improved function after massage and acupuncture was predicted by pretreatment expectancy regardless of which treatment patients actually received.
Given the ’implicit threat’ explanation of pain, treatment possibilities become vast. In theory anything that is capable of manipulating inputs that are contributing to the implicit threat perception could help to alleviate pain for example pain education, graded exposure to threatening movements and or manual therapy techniques. Some techniques may alter several inputs at once, for example manual techniques may alter sensory-motor inputs and also influence a patients beliefs about their condition. By manipulating inputs we can alter outputs.

Pain does not reflect the level of damage in the tissues

The knowledge that pain does not reflect the level of damage in the tissues, but rather is a conscious driver of behaviour aimed a protecting those tissues, has key implications for clinical practice. The skills and knowledge of clinicians need to adequately reflect modern pain biology and be broader than tissue anatomy and biomechanics.

Patients education is also key- patients should be helped to base their own reasoning, about their symptoms, on modern pain science. The finding that patient education can be an effective pain treatment ties in perfectly with concepts of decreasing the implicit perception of threat. Teaching patients about modern pain biology leads to altered beliefs and attitudes about pain [10] and increases pain thresholds during relevant tasks.

So, how about pain being described as an illusion? Should this be an explanation we teach patients and clinicians?? Personally, I think that this could be a useful explanation for chronic pain sufferers. This explanation could help patients accept the notion that hurt does not necessarily equate with harm, thus empowering them to increase their activity levels and not rely on passive, tissue-focused treatments.

And for us clinicians, the possibilities for advances in pain treatment become endless, as we move away from postural- biomechanical (tissue based focus) paradigms to concepts of re-educating the nervous system, manipulating system inputs and outputs, and ultimately changing our patient’s ‘pain illusions’.

References:

[1] Gifford, L. (1998). Pain, the Tissues and the Nervous System: A conceptual model. Physiotherapy, 84(1), 27–36.

[2] Moseley, G. L. (2007). Reconceptualising pain according to modern pain science. Physical Therapy Reviews, 12(3), 169–178.

[3] Fields, H L and Basbaum, A I (1994). ‘Central nervous system mechanisms of pain modulation’ in: Wall, P D and Melzack, R (eds) op cit, 3rd edn, pages 243-257.
[4] The influence of anxiety on pain: attentional and attributional mediators. (1994). The influence of anxiety on pain: attentional and attributional mediators.56(3), 307–314.

[5] Gallace, A., Torta, D. M. E., Moseley, G. L., & Iannetti, G. D. (2011). The analgesic effect of crossing the arms. Pain, 152(6), 1418–1423.

[6] Kammers, M. P. M., de Vignemont, F., & Haggard, P. (2010). Cooling the thermal grill illusion through self-touch. Current biology : CB, 20(20), 1819–1822.

[7] A supramodal representation of the body surface. (2011). A supramodal representation of the body surface., 49(5), 1194–1201.

[8] Preston, C., & Newport, R. (2011). Analgesic effects of multisensory illusions in osteoarthritis. Rheumatology, 50(12), 2314–2315.

[9] Kalauokalani D, Sherman KJ, Cherkin DC. Acupuncture for chronic low back pain: diagnosis and treatment patterns among acupuncturists evalu- ating the same patient. South Med J. 2001;94:486–492.
[10] Moseley GL, Nicholas MK, Hodges PW. A randomized controlled trial of intensive neurophysiology education in chronic low back pain. Clin J Pain 2004;20:324–30

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