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The effects of a conditioning stimulus provided as cold pressor test on the conditioned pain modulation of healthy persons based on the subjective experience of pain

Dekker, M.G. and Haan, J.S. de and Malki, A. and Willemse, I.H.J. (2016) The effects of a conditioning stimulus provided as cold pressor test on the conditioned pain modulation of healthy persons based on the subjective experience of pain.

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Abstract:Chronic pain is burdening, both physically and psychologically. A special form is chronic post surgical pain. Since there are operations with up to 85% chance on chronic pain, research to a predictive value to generate chronic pain is important. The human body has its own mechanism for the prevention of pain perception, called Conditioned Pain Modulation (CPM). The performance of this mechanism is related to the development of chronic pain so further understanding of the subject is valuable. A painful conditioning stimulus (like a Cold Pressor Test, CPT) activates this modulation but there are also observations of inhibiting activity while the conditioning stimulus was not painful. Furthermore the behaviour in time of this effect and its reproducibility are not well known yet. The subjective pain experience is most important because this causes the inconvenience for the patient. This all leads to the question: What are the effects of a conditioning stimulus provided as Cold Pressor Test on the Conditioned Pain Modulation system of healthy persons on the basis of subjective experience of pain? A group of 22 healthy volunteers (50% male, 50% female) between the ages of 17 and 54 participated in this study. The study consisted of one session. For five of the 22 participants it were two identical sessions on two separate days to research reproducibility. All participants endured four CPTs, all until a different pain level. The painful CPTs (NRS 10, 6 and 4) were in 0-2C water and a painless one (NRS 0) in 33-34C. The order of NRS 6, 4 and 0 was randomized. Each CPT was preceded and followed by three electrical stimuli to determine the EPDT (Electrical Pain Detection Threshold) with the NociTrack. The participant self administered this current until the feeling became unpleasant. The difference between these EPDT values shows the CPM effect and can be compared to understand the differences between achieving different pain levels. To research behaviour in time, after the first CPT each 5 minutes the EPDT is measured again. For the main variable condition, NRS 10 differs signifcantly from NRS 6, 4 and 0. For the other main variable pre and post EPDT, the values differ significantly for all conditions except NRS 0. For the interaction effect between these variables, there is no significant value. By means of pairwise comparison is shown that the CPM effect is present but not deviating between the four conditions. From the second condition on, the CPTs were administered in randomised order. From this study can be concluded that the order is irrelevant. When separated for order the combined results for NRS 6, 4 and 0 are the same as when separated for condition. There seems to be a slight increase in relative difference in EPDT value in time, but it is pointed out that the change of EPDT in time is not significant. A factor that might play a role in this observation is habituation to the test stimulus. Earlier research mentions that there is still a CPM effect an one hour after the first conditioned stimulus is applied. This factor could also be a declaration that there is no significant difference in EPDT over time. Only one of the five participants shows reproducibility for the re-test at the four conditions with a deviation at NRS 10 and one participant shows a decrease when we compare the test and re-test to each other. Most participants show a decrease of the CPM effect when we compare the test and the re-test at the five different times after CPT 1. The group of five participants is to small in order to give reliable results. Further research is needed with at least 15 participants.
Item Type:Essay (Bachelor)
St. Antonius Nieuwegein, Nieuwegein, Nederland
Faculty:TNW: Science and Technology
Subject:44 medicine
Programme:Technical Medicine BSc (50033)
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