Marjolein Kammers has been doing some excellent research including a study on self-touch. It is quite usual to rub ourselves better when something hurts as well as look at the area to check it out and often move it or ‘shake it off’. This recent paper looks at effects of self-touch upon the thermal grill illusion. Here is the abstract from Current Biology (2010), 20, 1819-1822:
Acute peripheral pain is reduced by multisensory interactions at the spinal level . Central pain is reduced by reorganization of cortical body representations [2, 3]. We show here that acute pain can also be reduced by multisensory integration through self-touch, which provides proprioceptive, thermal, and tactile input forming a coherent body representation [4, 5]. We combined self-touch with the thermal grill illusion (TGI) . In the traditional TGI, participants press their fingers on two warm objects surrounding one cool object. The warm surround unmasks pain pathways, which paradoxically causes the cool object to feel painfully hot. Here, we warmed the index and ring fingers of each hand while cooling the middle fingers. Immediately after, these three fingers of the right hand were touched against the same three fingers on the left hand. This self-touch caused a dramatic 64% reduction in perceived heat. We show that this paradoxical release from paradoxical heat cannot be explained by low-level touch-temperature interactions alone. To reduce pain, we often clutch a painful hand with the other hand. We show here that self-touch not only gates pain signals reaching the brain [7-9] but also, via multisensory integration, increases coherence of cognitive body representations to which pain afferents project .
This is both very interesting and of real practical use. Of course in some situations it is very challenging to perform self-touch due to the sensitivity but can form part of the desensitising process. Desensitisation is part of the rehabilitation programme and tackled in a range of ways, both locally at the tissue level and also at a brain level through deeper understanding of pain and CRPS, effective coping strategies techniques such as graded motor imagery.
Not only did the self-touch reduce the pain, but developed coherence. The brain likes things to make sense. When the information from the tissues does not make sense as is the case when the flow is altered in on-going pain and injury, it creates threat. The brain must respond to threat, whether this be physical (e.g. movement) or psychological (e.g./ fear of movement), and does so with protective measures that include pain. Creating coherence by adding information through touch can help to reduce the threat. This is why looking at the area can also help. On this basis I often ask people to touch, look and move. However, this is on a background of understanding and within a context of developing mastery of one’s situation in order to move forwards.
Please contact me for further details or if you have questions about the modern neuroscience based approach to CRPS and chronic pain.