The influence of a manipulation of threat on experimentally-induced secondary hyperalgesia

Abstract

Pain is thought to be influenced by the threat value of the particular context in which it occurs. However, the mechanisms by which a threat achieves this influence on pain are unclear. Here, we explore how threat influences experimentally-induced secondary hyperalgesia, which is thought to be a manifestation of central sensitization. We developed an experimental study to investigate the effect of a manipulation of threat on experimentally-induced secondary hyperalgesia in 26 healthy human adults (16 identifying as female; 10 as male). We induced secondary hyperalgesia at both forearms using high-frequency electrical stimulation. Prior to the induction, we used a previously successful method to manipulate threat of tissue damage at one forearm (threat site). The effect of the threat manipulation was determined by comparing participant-rated anxiety, perceived threat, and pain during the experimental induction of secondary hyperalgesia, between the threat and control sites. We hypothesized that the threat site would show greater secondary hyperalgesia (primary outcome) and greater surface area (secondary outcome) of induced secondary hyperalgesia than the control site. Despite a thorough piloting procedure to test the threat manipulation, our data showed no main effect of site on pain, anxiety, or threat ratings during high-frequency electrical stimulation. In the light of no difference in threat between sites, the primary and secondary hypotheses cannot be tested. We discuss reasons why we were unable to replicate the efficacy of this established threat manipulation in our sample, including: (1) competition between threats, (2) generalization of learned threat value, (3) safety cues, (4) trust, and requirements for participant safety, (5) sampling bias, (6) sample-specific habituation to threat, and (7) implausibility of (sham) skin examination and report. Better strategies to manipulate threat are required for further research on the mechanisms by which threat influences pain.

The impact of the social context on the development of secondary hyperalgesia: an experimental study

“…Although the effect size is small, our findings are in line with studies that have shown that other top-down factors can modulate SH [22,32,45,57,67]. Importantly however, other recent studies that have used similar electrical stimulation protocols, have found either modest or no modulation of SH [4,18,48,65]. This apparent difficulty may be due to the intense nature of the electrical stimulation and the large magnitude of SH that these procedures induce (eg.…”

“…22,32,45,58,68 Importantly however, other recent studies that have used similar electrical stimulation protocols have found either modest or no modulation of SH. 4,18,48,66 This apparent difficulty may be due to the intense nature of the electrical stimulation and the large magnitude of SH that these procedures induce (eg, h p 2 5 0.47 in the current study). In addition, MFS stimulation induces the largest increase in perceived pinprick intensity compared with other frequencies.…”

The Impact of the Social Context on The Development of Secondary Hyperalgesia: An Experimental Study

“…Although the effect size is small, our findings are in line with studies that have shown that other top-down factors can modulate SH [22,32,45,57,67]. Importantly however, other recent studies that have used similar electrical stimulation protocols, have found either modest or no modulation of SH [4,18,48,65]. This apparent difficulty may be due to the intense nature of the electrical stimulation and the large magnitude of SH that these procedures induce (eg.…”

The Sensation and Pain Rating Scale: easy to use, clear to interpret, and responsive to clinical change

“…The SPARS has good psychometric properties [27]. Several studies have used [4; 8; 25; 36] or adapted [16] it as an outcome measure.…”

“…Experimental testing of the SPARS showed good psychometric properties and, usefully, a stable curvilinear stimulus-response relationship supporting parametric statistics and calculations of percentage changes in pain (in contrast to the conventional NRS or VAS) (Madden et al, 2019; Price, Bush, Long, & Harkins, 1994; Price, McGrath, Rafii, & Buckingham, 1983). Several studies have used (Bedwell et al, 2022; Chaves et al, 2021; Madden et al, 2016; Traxler, Madden, Moseley, & Vlaeyen, 2019) or adapted (Ho et al, 2022) it as an outcome measure.…”