title: Adaptability to pain is associated with potency of local pain inhibition, but not conditioned pain modulation: a healthy human study.
abstract: This study investigated the relationship between pain sensitivity, adaptability, and potency of endogenous pain inhibition, including conditioned pain modulation (CPM) and local pain inhibition. Forty-one healthy volunteers (20 male, 21 female) received conditioning stimulation (CS) over 2 sessions in a random order: tonic heat pain (46 °C) on the right leg for 7 minutes and cold pressor pain (1 °C to 4 °C) on the left hand for 5 minutes. Participants rated the intensity of pain continuously using a 0 to 10 electronic visual analogue scale. The primary outcome measures were pressure pain thresholds (PPT) measured at the heterotopic and homotopic location to the CS sites before, during, and 20 minutes after CS. Two groups of participants, pain adaptive and pain nonadaptive, were identified based on their response to pain in the cold pressor test. Pain-adaptive participants showed a pain reduction between peak pain and pain at end of the test by at least 2 of 10 (n=16); whereas the pain-nonadaptive participants reported unchanged peak pain during 5-minute CS (n=25). Heterotopic PPTs during the CS did not differ between the 2 groups. However, increased homotopic PPTs measured 20 minutes after CS correlated with the amount of pain reduction during CS. These results suggest that individual sensitivity and adaptability to pain does not correlate with the potency of CPM. Adaptability to pain is associated with longer-lasting local pain inhibition.
authors: School of Health Sciences and Traditional and Complementary Medicine (TCM) Research Program, Health Innovations Research Institute, RMIT University, Bundoora, Australia Center for Sensory-Motor Interaction, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
authors: Zhen
authors: Z
authors: Zheng
authors: Kelun
authors: K
authors: Wang
authors: Dongyuan
authors: D
authors: Yao
authors: Charlie C L
authors: CCL
authors: Xue
authors: Lars
authors: L
authors: Arendt-Nielsen
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D003080:Cold Temperature; D003213:Conditioning, Psychological / Q000502:physiology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D010812:Physical Stimulation; D011312:Pressure; D055815:Young Adult
keywords: Conditioned pain modulation; Diffuse noxious inhibition control; Pain adaptability; Pain sensitivity; Pain tolerance; Segmental inhibition; Tonic pain