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Is it time to rethink the official definition of pain? What do you think?


Definition IASP: “pain is an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage,” 


In the definition of the IASP, the focus is on tissue damage. This suggests that the purpose of the pain system (nociceptive apparatus) is to protect tissue integrity. This does not seem entirely correct to us.  We are a multicellular organism, a collaboration of cells, living in a flexible aquarium (fascia). Everything revolves around the the cell. It is more logical that the primary purpose of the nociceptive apparatus is to protect the living cell rather than tissue integrity. Of course tissue damage is a threat to the cell, but it is not the only one.


The safety of the cells is compromised if the living environment (interstitial fluid) changes unfavorably. There are several forms of threat and the most important is probably acidification of the interstitial fluid. This can be caused by inflammation, ischemia and/or muscle activity. Cells cannot function properly in an acidic environment and therefore chemonocisensors will be activated. This will sensitize mechanosensors, possibly leading to pain when the tissue is loaded. In this way, nociception can occur without any form of tissue damage. It is about fluids!


Acidosis increases the viscocity of the interstitial fluid, making it thicker and stickier. This is called a densification. These densifications can be very localised. An example of this is a trigger point. Dr. J. Shah has demonstrated, by microdialysis of the interstitial fluid, inflammation and acidity in the direct vincinity of a trigger point. The thickness we feel on palpation is likely the densification that is caused by the acidity. Liquifying these densifications by manual techniques often resolves the pain. About 70-85% of chronic pain patients are estimated to have active trigger points.


Just an example:

This woman has had years of chronic pain in the right knee and hip. In spite of a lot of physiotherapy and pain rehabilitation the pain has increased over the years. At this point she is not able to walk without crutches, ride a bicycle or drive a car. MRI showed cartilage damage. The orthopaedic surgeon could offer no other option than wait untill she would be old enough for a knee replacement. Palption demonstrated very localised painful spots in the soft tissues (no pressure on the cartilage). The pain is too to be explained by an oversensitve nervous system. After liquifying all the densifications she was able to walk, drive, cycle and even jump completely without pain.


We describe a hypothesis in this post. If this hypothesis is correct, this can have major consequences, for example:

  • Acknowledgment for patients who have been told that nothing is physically wrong and that it is “all-in-the-brain” or “all-in-the-head”. No findings on X-ray and MRI does not mean that there is no nociception. Even in the absence of tissue damage, there can be nociception from the "invisible" soft tissues (read: "fluids").

  • This may explain much of the ‘medical unexplained’ or ‘aspecific’ pain (in combination with central sensitisation).

  • This may improve our understanding the effects of hands-on therapies and exercises.

  • This may lead to forms of pain reducing treatments (we actually see quite promising results with our therapy based on this hypothesis).

  • Cost reduction: Improving palpation skills may prevent a number of X-rays and MRI’s. Especially in people with chronic pain.


We think that it makes sense for therapists to focus more on soft tissues (fluids) than on hard tissues (bone, cartilage, tendons, etc.). Could it be that loss of homeostasis is more common source of nociception than tissue damage?

We understand why tissue damage is used in the definition of pain as we are all too familiar with the experience of pain when injured. But if pain is foremost about protection of the cell maybe this should (also) be reflected in the definition.


We would like to hear your thoughts on this matter.

contact Ernst van der Wijk:

Useful web sites






Website for patient and referrers,

Training fasciatherapy FIT for physiotherapists

For courses abroad

Tips for more resilience

Tools for fascia mobilization and training

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