Relationship between cardiovascular reactivity and the perception of the thermal grill illusion of pain

Alterations in blood pressure (BP) and concomitant changes in
baroreceptor activation contribute to the modulation of pain
sensitivity to warrant homeostatic regulation processes [1][2].
Numerous pain studies have described an inverse relationship
between BP and nociceptive sensitivity [3][4][5]. It is not
known whether a similar relationship plays a role in the
framework of the induction of pain in the absence of noxious
stimulation. The thermal grill (TG) paradigm is commonly
used to trigger this type of paradoxical pain also termed
thermal grill illusion of pain (TGI).
The goal of the present study was to explore the relationship
between cardiovascular activity/reactivity and paradoxical pain
sensitivity to get additional insight in the variability of
responsiveness (responders and non-responders) to TG
stimulation described in the literature [6][7]. We hypothesized
that higher BP would be associated with stronger pain
inhibitory effects in participants not perceiving the thermal grill
illusion of pain (TGI). We moreover expected that the
perception of paradoxical pain in the responder group would be
paired with lower BP. We tested this hypothesis by comparing
both groups with respect to their spontaneous cardiovascular
activity (recorded in resting conditions) and their
cardiovascular responses to TG stimulation.