I have essentially invented and over time refined a metaphor explaining pain sensitisation in a simpler manner that is more easily understood and related to what is seen commonly at the coalface.

It explains pain sensitisation as a spectrum  condition. This is just plain old common sense and I expand on this logical perspective in my blog - “Sorry, but there are SO many more than 50 shades of grey in pain”.

This view of pain sensitisation is important. It is preferable to the bizarre 'you've either got it or you don't and if I think you don't, I'm going to keep trying to fix all the things I see on your scan' approach currently being fostered because of the current  'accepted' definitions. Despite these well-intentioned, yet paradoxically linear, consensus derived definitions, the concepts generated from them are leading to harms because sensitisation processes are not being recognised early enough.

I use this metaphor in my presentations and with my patients in my office. Despite being a little visual I even used it in a discussion on a radio interview and it seemed to be understood by friends who gave me positive feedback.

So here it is now officially on my website  introduced by this image which is a key slide from the presentation I give regularly on pain -


Consider that your finger is approaching a flame.

Firstly, if you wave your finger through the flame quickly you feel nothing. The signalling input to pain is either not stimulated due to the speed, or your brain simply knows that there is no danger and so there is no pain response required for protection, or both.

But, if your finger approaches slowly and there is conscious awareness of potential harm, the heat causing pain is felt at a distance before the flame. This feeling does not allow your finger to get so close that it is harmed by being burnt. This already conveys an important insight that PAIN OCCURS BEFORE HARM AS A WARNING ALARM.

However, the most important consideration of this metaphor is that as pain persists FOR ANY REASON (ongoing input signalling, perception of harm alone, contextual influences etc), the distance between the finger and the flame increases subtly. What used to be felt at a smaller distance is now felt identically at a larger distance. And this distance can change from time to time and in different environments. It is not static.

This is subtle, often undetectable (on standard criteria) SENSITISATION of the pain processing system producing the same or greater pain response for a lesser protective reason.

Want justification of this?

Ask all with persistent pain how their pain changes with time? You will find consistently in a very large number (? all) that it becomes progressively more easily aggravated, more constant etc. That change is logically unexplainable by the 'injury' or visible 'tissue change' alone.

I conclude this metaphor with the overtly sensitised group (according to standard criteria). These people are in agonising pain independent of 'damage'; a large number of them cannot tolerate the feeling of even clothes on their skin and similar 'provocation'. PLEASE CONSIDER HOW FAR THEIR FINGER IS AWAY FROM THE SAME FLAME FEELING THE SAME PAIN AS IF QUITE CLOSE. IT IS OUT IN THE STREET SOMEWHERE.

I cannot think of too many things in life that are truly 'all or nothing'. There are always shades of grey. Ignoring subtle sensitisation processes in the early phases is not helpful as it diverts attention to applying 'fixes' to what is thought mistakenly to be the 'main' problem based simplistically on things that are seen on scans. That approach is resulting in increasingly many getting BURNT!