Expectations Modulate Heterotopic Noxious Counter-Stimulation Analgesia

Expectancy Effects on Conditioned Pain Modulation Are Not Influenced by Naloxone or Morphine

“…These findings are consistent with those of Goffaux and colleagues who demonstrated that participants who were told to expect that a CPM paradigm would decrease their pain subsequently reported such a decrease, whereas those who were told to expect that it would increase their pain reported no significant change [10]. Similar results were obtained by Cormier and colleagues [12], although in their study the expectancy of hyperalgesia was associated with a marginal increase in pain ratings and a significant increase in NFR activity. Lastly, we observed a correlation between the change in heat pain that participants expected and their subsequent change in reported heat pain ratings that was almost identical to that reported by Larivière and colleagues (i.e., r = 0.26 and r = 0.27, respectively) [11].…”

“…One important limitation is that, unlike prior reports that have incorporated NFR assessments as part of the test stimulus to provide an objective measure of nociceptive responding [10, 12], the present findings are based on subjective reports of thermal pain. Hence, the observed change in test stimulus pain ratings may reflect differences in the participants’ experience of heat pain, differences in participant willingness to report pain, or some combination thereof.…”

“…Other studies have reported that naloxone has no effect on CPM analgesia [7–9]. Whereas the lack of uniform findings may be attributable to a variety of factors (e.g., diverse conditioning and test stimuli; different opioid antagonists, doses, and routes of administration; small samples), individual differences in expectancy during CPM testing may also play a role [10–12]. For example, Goffaux and colleagues [10] conducted a CPM study in which participants were told to expect that immersion of their arm in cold water would either increase or decrease electrical pain during nociceptive flexion reflex (NFR) assessment.…”

“…Although expectancy was not the primary focus of that study and therefore did not receive significant attention in the analyses, it was reported that participant expectations were positively correlated with CPM-related changes in heat pain threshold values ( r = 0.27, p = 0.057). More recently, these design elements were combined in a CPM study that assigned participants to one of four groups: no-manipulation control, hypoalgesia expectation, hyperalgesia expectation, or self-reported expectation (wherein 80% anticipated a decrease in pain) [12]. Reductions in pain ratings and NFR activity were observed in all groups except the hyperalgesia expectation group, which showed increases in pain ratings ( p = 0.09) and NFR activity ( p < 0.001).…”

Role of endogenous pain modulation in chronic pain mechanisms and treatment

“…Nir et al 65 found in healthy controls that suggestion of change in the intensity of the conditioning stimulus affected CPM efficiency; subjects who believed that the unchanged conditioning stimulus was lowered, reduced their CPM effect, emphasizing the influence of brain processes over the spinal-bulbo-spinal CPM effect. Cormier et al 15 showed that CPM efficiency is influenced by suggestion to its efficiency. Two articles examined the influence of dispositional optimism on CPM, which found that healthy controls reporting optimism had more efficient CPM, 25,26 with possible influence of pain catastrophizing on this association.…”