15 Feb 2018

The Wizard of Oz

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Professor Lorimer Mosely has my greatest respect and admiration for the work he has done and his search for the understanding of pain, but I worry about how his work is interpreted.

He uses visual and proprioceptive illusions to demonstrate that the senses can be fooled. Experiments like the rubber hand experiment prove that we can perceive our body incorrectly under experimental conditions. They do not prove that our senses are unreliable.

Just as the magician creates the illusion that a coin can disappear, or a signed card can leap from the pack, illusions prove nothing about reality.

We are more than aware that our eyes can create the illusion of water in the distance which why we use our other senses to find out whether what we see is a lake or a mirage.

We vertebrates could not have survived so long with faulty senses.

Professor Mosely describes these illusions with comic genius, authority, talk of the posterior parietal lobe and great story-telling. He creates a narrative so seductive, we must believe the trick is real.

If we believe the tricks, then we might believe that pain has nothing to do with tissue damage and that it really is a construct that only occurs in the brain.

Both of these ideas are patently wrong, but it seems like a whole generation of manual therapists believe them.

If pain is an illusion, then we should be able to create it at will. Try as I might, I cannot create the pain of a broken leg or a kidney stone with my imagination. Can you?

People who have not been exposed to the The Great Oz know that the only reliable way to experience pain, is through induction of tissue damage. It is true that some tissues (those without a sensory nerve supply) can be damaged without causing any pain, but generally, tissue damage is a reliable producer of pain.

It is also true that the senses can be fooled temporarily into believing that the scratch on one’s leg is a twig rather than a snake bite, but our senses soon correct our mis-interpretation.

This leaves the problem of what to think about people in pain with no identifiable tissue damage and the equally perplexing problem of identical conditions responding differently to the same therapy in different people.

It is tempting to presume that the problem is somehow in their brain or their perception, after all Professor Mosely’s experiments show this is possible. But this is a diagnosis of exclusion, it is not a confirmatory diagnosis. One could equally explain the problem on the basis disfavour of the Gods. If you want to prove that psychology or contextual factors can cause pain then you have to be able to create pain with psychology or contextual factors.

Sadly, this makes it all too easy for a healthcare provider to put the onus of care on the patient, which is convenient when the available research reassures them that physical treatment is likely only minimally successful.

To accept a negative diagnosis for pain is to accept magical thinking. In the real world, effects have causes. We just have to get better at finding them.

If we can’t determine the cause of pain, then let’s get better at that until we can. We are dealing with an immensely complex organism with millions of simultaneous inputs. Skin receptors can feel one hair move, the simplest of movements requires the coordination of 86 billion neurons each connected to 7000 others. It is hardly surprising that we fail to detect the inflammation and tissue damage that causes pain.

I know the old biomechanical and musculoskeletal paradigms are broken, but let’s be careful about embracing a paradigm based on illusions.

1 Response

  1. Cam

    Hi Simon
    Which “IS”why..even better maybe a comma then “that is why
    “We”invertebrates.
    Professor mosely has a orofile here ..on radio the other day ..rightly points out medication has been ineffective and harmful..best to see physio o.t. etc. No mention of chiro.

    Disappoints me that we have such a low even negative image as a profession..when i know and am told every day that i have far better results than the 6 physios surrounding me.

    Yet doctors still refer to physios and even dissaude them from seeing chiro.

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