TY - JOUR
T1 - Offset analgesia is not affected by cold pressor induced analgesia
AU - Nissen, Thomas Dahl
AU - Mørch, Carsten Dahl
AU - Arendt-Nielsen, Lars
AU - Drewes, Asbjørn Mohr
AU - Olesen, Anne Estrup
PY - 2018
Y1 - 2018
N2 - Background and aims: Offset analgesia (OA) is a pain modulating mechanism described as a disproportionately large decrease in pain intensity evoked by a minor decrease in stimulus intensity. Precise mechanisms of OA are still not elucidated and studies are needed to evaluate factors modulating OA. The aim of this study was to investigate OA before and during tonic cold pain (thought to induce descending inhibition), in a group of healthy volunteers. Methods: A randomized, crossover study was performed in 17 healthy participants (8 males and 9 females). The OA paradigm lasted 35 s and was induced by the traditional method using thermal stimulation applied to the forearm. A constant control heat stimulus (CTL) paradigm was used as control to assess adaptation. Pain intensity was assessed continuously. For induction of tonic cold pain, the participants immersed their hand into 2 °C water for 2 min. After 1 min and 25 s, the heat stimulation (OA or CTL paradigm) was repeated to assess the modulatory effect of the cold pressor test. Results: It was possible to induce OA both before and during the cold pressor test. Tonic cold pain modulated the peak pain reported during both the OA (p = 0.015) and CTL paradigms (p = 0.001) reflecting endogenous pain modulation. However, the magnitude of OA was not modulated by tonic cold pain (p > 0.05). Conclusions: The offset analgesia magnitude was not modulated by simultaneously tonic cold pain, thought to reflect another endogenous pain modulation mechanism. Implications: Neither offset analgesia magnitude nor adaptation were modulated by cold pressor induced endogenous analgesia. This could be explained by the fact, that offset analgesia was already at maximum in healthy participants. Hence, offset analgesia may not be a suitable assessment tool to investigate modulation induced by experimental methods or pharmacology in healthy participants.
AB - Background and aims: Offset analgesia (OA) is a pain modulating mechanism described as a disproportionately large decrease in pain intensity evoked by a minor decrease in stimulus intensity. Precise mechanisms of OA are still not elucidated and studies are needed to evaluate factors modulating OA. The aim of this study was to investigate OA before and during tonic cold pain (thought to induce descending inhibition), in a group of healthy volunteers. Methods: A randomized, crossover study was performed in 17 healthy participants (8 males and 9 females). The OA paradigm lasted 35 s and was induced by the traditional method using thermal stimulation applied to the forearm. A constant control heat stimulus (CTL) paradigm was used as control to assess adaptation. Pain intensity was assessed continuously. For induction of tonic cold pain, the participants immersed their hand into 2 °C water for 2 min. After 1 min and 25 s, the heat stimulation (OA or CTL paradigm) was repeated to assess the modulatory effect of the cold pressor test. Results: It was possible to induce OA both before and during the cold pressor test. Tonic cold pain modulated the peak pain reported during both the OA (p = 0.015) and CTL paradigms (p = 0.001) reflecting endogenous pain modulation. However, the magnitude of OA was not modulated by tonic cold pain (p > 0.05). Conclusions: The offset analgesia magnitude was not modulated by simultaneously tonic cold pain, thought to reflect another endogenous pain modulation mechanism. Implications: Neither offset analgesia magnitude nor adaptation were modulated by cold pressor induced endogenous analgesia. This could be explained by the fact, that offset analgesia was already at maximum in healthy participants. Hence, offset analgesia may not be a suitable assessment tool to investigate modulation induced by experimental methods or pharmacology in healthy participants.
KW - cold-pressor
KW - conditioned pain modulation
KW - offset analgesia
KW - pain
U2 - 10.1515/sjpain-2018-0082
DO - 10.1515/sjpain-2018-0082
M3 - Journal article
C2 - 30307901
AN - SCOPUS:85049758176
SN - 1877-8860
VL - 18
SP - 695
EP - 701
JO - Scandinavian Journal of Pain
JF - Scandinavian Journal of Pain
IS - 4
ER -