Pain changes our view of things

Chronic pains influence the way we perceive movements / study of patients with back and shoulder pain published in the journal "PAIN"

Münster (upm), Di, 29 Mai 2012

Patients with chronic back or shoulder pain see the world around them through different eyes than healthy people do – at least, this is true for the parts of the body causing them the pain. This is what is indicated by a study which was carried out by an interdisciplinary team of scientists from Münster and Jena and has now been published in the latest issue of the journal "PAIN". The study found that chronic pain not only has an effect on the body of the patients concerned – it can also influence the way that patients who are in pain perceive the movements they observe in other people. The judgements they make of these people change relative to the movements which would cause them pain themselves.

The scientists, who are part of the joint research project "Chronic Back Pain" being funded by the German Ministry of Education and Research, showed to test persons with chronic shoulder or back pain point-light videos of people carrying out a variety of movements. In these exercises, either the shoulder area or the back area of the point-light figures was subjected to pressure through weights being lifted. Point-light figures display in an abstract way the movements that real people make. In this process, the person is reduced to a series of light points on a dark background - representing, for example, the head, hands, feet and joints.

What the test persons had to do was to estimate how heavy the weights were which the figures had lifted. The healthy test persons were able to distinguish the different weights in both exercises. On the other hand, those with backache were able to guess the weights in the shoulder exercise – but not in the back exercise, which would be painful for them. By contrast, test persons with shoulder pain had difficulties in assessing the weights in the shoulder exercise, but not in the back exercise.

According to the scientists, the explanation for this is to be found in the brain – in the cerebral cortex region, where the nerve cells process somatosensory information. The activity of nerve cells in certain regions of the brain in the so-called frontal and parietal cortex is, in the case of chronic pain, different from the patterns of activity found in the brain of a healthy person. "Patients with chronic pain are often physically fit again, but there is still a 'pain memory' in the brain – and there is no matching process with the actual situation in the body," explains Dr. Marc de Lussanet, a biologist at the Otto Creutzfeld Centre for Cognitive and Behavioural Neurosciences at Münster University, who is involved in the study as lead author.

In addition to touch stimuli, special visual stimuli are also processed in the frontal and parietal cortex – visual stimuli which are caused by observing movements, e.g. a sports exercise which another person is carrying out. There is evidently a connection between both networks, as the study demonstrates. "For the first time," says Marc de Lussanet, "we have been able to show that there is a direct connection between chronic pain and the recognition of movements made by other people. Chronic pain changes the way stimuli are processed by neuronal networks in the brain, which are involved in the recognition of these movements. The perception of one's own body overlaps with the perception of what one sees in other people." The scientists suggest that therapies to reactivate the "movement recognition networks" in the brain could be used to treat chronic pain.

Background information

The studies took place as part of a joint research project funded by the German Ministry of Education and Research. Since July 2011 the Ministry has been providing funding for an interdisciplinary team of researchers from the fields of movement sciences, psychology and medicine at the Universities of Münster and Jena. The research programme is entitled "Chronic backache and sensomotoric control: towards the development of a model-based diagnostic set of instruments" ("Chronic Back Pain"). The aim is to develop new diagnostic procedures and understand chronic back pain better.


Original publication:

Marc H.E. de Lussanet, Frank Behrendt, Christian Puta, Thomas Weiss, Markus Lappe, Tobias L. Schulte, Heiko Wagner (2012): A body-part-specific impairment in the visual recognition of actions in chronic pain patients. PAIN In Press/available online; DOI: 10.1016/j.pain.2012.04.002

Otto Creutzfeld Centre Original publication

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