The Pain Neuromatrix

The pain neuromatrix was a concept that came from Ron Melzack who partnered Pat Wall in developing our understanding of pain in a modern sense. Moving on from the Pain Gate Theory, Melzack described a widespread distribution of neurons (brain cells) that imprint a 'neurosignature' upon nerve impulse patterns that pass through the matrix. The neurosignature creates our experience of self including movement and pain. We have an overall neurosignature for our sense of self and subsets of patterns that give us unique experiences such as pain, warmth and other qualities that are produced by these modules.

Melzack (2004) describes four components of this concept including the 'body self' where we have the experience of ourselves as a result of the unification of information from the body, the processing and synthesis of the signature, the sentient neural hub that converts the processes into awareness and the subsequent action to achieve the desired goal. In terms of pain as an output from the brain, this would be the end result of an activation of the pain neuromatrix with a characteristic signature, the pain signature. Pain is part of a multi system response to a perceived threat. There are many inputs to the brain that can trigger the pain neuromatrix including movement, thoughts, emotions, touch, memories, fear and visual stimuli to name but a few. The reason that these stimuli can trigger a pain response is in essence due to a perceived threat but also due to the fact that the widespread neurones that make up the pain matrix are involved in all of the aforementioned activities but are also part of the pain neuromatrix.

The neuromatrix model provides an excellent explanation for higher level parallel processing of information and the output that occurs as a smooth mechanism creating our conscious experience. Melzack points out that the matrix is genetically determined and moulded by sensory input. This makes sense as we continue to learn as we have new experiences, the nervous system being incredibly plastic (Doidge, 2007). Describing this to patients allows them to understand why there are so many influences upon the pain that they suffer, even if they are unaware of the exact stimulus. In many cases of chronic pain the patient describes an increase in symptoms despite no change in their daily routine. The neuromatrix allows us to look at some of the possible reasons for a flare-up and give reassurance that they have done no 'damage' in the case that there has been no further injury. Empowering the individual with the knowledge that hurt does not mean harm can be extremely useful in many cases.

Evolution of the neuromatrix theory of pain. The Prithvi Raj Lecture: Presented at the Third World Congress of World Institute of Pain, Barcelona 2004. Pain Practice, 5(2), 85-94
The brain that changes itself. Doidge, N. (2007)