Introduction: Offset analgesia describes the effect of a slightly reduced nociceptive stimulus, resulting in a disproportionate large reduction in the pain perception. This effect may be associated with descending pain inhibition, but parameters influencing this phenomenon are poorly understood.
Objectives: In this study, 2 separate experiments were conducted to investigate both, the spatial aspects of offset analgesia and the influence of different rates of temperature rise.
Methods: In both experiments, 29 healthy participants received individualized and heat-based offset analgesia paradigms applied to the forearm, with continuous assessment of pain intensity. In experiment 1, offset analgesia paradigms with 3 different rates of temperature rise were applied, whereas in experiment 2, offset analgesia paradigms with 2 different heat application areas were used.
Results: The results of experiment 1 showed that different temperature rates had no effect on the offset analgesia response (P > 0.05). Experiment 2, however, showed the influence of the size of a stimulated area on offset analgesia (P = 0.009), which can be explained mainly by the influence of spatial summation of pain and habituation processes.
Conclusions: The study showed a lack of influence of different temperature rates on offset analgesia; however, spatial aspects of offset analgesia could be identified. These are most likely based on spatial summation of pain and altered adaptation to pain.
Keywords: Central; Offset analgesia; Pain modulation; Peripheral; Temporal contrast enhancement.
Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The International Association for the Study of Pain.