Determinants of endogenous analgesia magnitude in a diffuse noxious inhibitory control (DNIC) paradigm: Do conditioning stimulus painfulness, gender and personality variables matter? Pain

Faculty of Social Welfare and Health Studies, University of Haifa, Israel.
Pain (Impact Factor: 5.21). 06/2008; 136(1-2):142-9. DOI: 10.1016/j.pain.2007.06.029
Source: PubMed


Descending modulation of pain can be demonstrated psychophysically by dual pain stimulation. This study evaluates in 31 healthy subjects the association between parameters of the conditioning stimulus, gender and personality, and the endogenous analgesia (EA) extent assessed by diffuse noxious inhibitory control (DNIC) paradigm. Contact heat pain was applied as the test stimulus to the non-dominant forearm, with stimulation temperature at a psychophysical intensity score of 60 on a 0-100 numerical pain scale. The conditioning stimulus was a 60s immersion of the dominant hand in cold (12, 15, 18 degrees C), hot (44 and 46.5 degrees C), or skin temperature (33 degrees C) water. The test stimulus was repeated on the non-dominant hand during the last 30s of the conditioning immersion. EA extent was calculated as the difference between pain scores of the two test stimuli. State and trait anxiety and pain catastrophizing scores were assessed prior to stimulation. EA was induced only for the pain-generating conditioning stimuli at 46.5 degrees C (p=0.011) and 12 degrees C (p=0.003). EA was independent of conditioning pain modality, or personality, but a significant gender effect was found, with greater EA response in males. Importantly, pain scores of the conditioning stimuli were not correlated with EA extent. The latter is based on both our study population, and on additional 82 patients, who participated in another study, in which EA was induced by immersion at 46.5 degrees C. DNIC testing, thus, seems to be relatively independent of the stimulation conditions, making it an easy to apply tool, suitable for wide range applications in pain psychophysics.

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Available from: Michal Granot, Mar 04, 2015
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    • "Immersion tests consisted in the immersion of the right arm (up to the elbow) in circulating cold (7 °C) or hot water (47.5 °C) during 5 min. These temperatures were shown to induce moderate pain in healthy subject (Tousignant-Laflamme et al., 2005; Granot et al., 2008). The sequence of both tests was alternated and participants were randomly assigned to sequence order and parallelized with respect to gender. "
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    ABSTRACT: Background: The mechanisms of adaptation to tonic pain are not elucidated. We hypothesized that the adaptability to tonic pain is related to the cardiovascular system. Methods: Twenty-six subjects received over two sessions in a random order: tonic cold (7 ± 0.2 °C) and heat pain (47.5 ± 0.5 °C) on the hand for 5 min. Pain intensity, blood pressure (BP), and heart rate (HR) were continuously monitored. Results: Pain experience during the heat (HIT) and cold (CIT) immersion tests exhibited different average time courses, being approximated with a linear and cubic function, respectively. In each test, two groups of participants could be identified based on the time course of their tonic thermal pain: one-third of participants were pain adaptive and two-thirds non adaptive. The adaptive group exhibited higher initial pain, lower last pain, and shorter latency to peak pain than the non-adaptive one. Interestingly, some participants were adaptive to both pain stimuli, most were not. HIT as well as CIT produced a stable elevation of BP. However, BP was higher during CIT than HIT (p = 0.034). HR was also increased during CIT and HIT, but the two tests differed with respect to the time course of responses. Finally, the intensity and time course of pain rating to both HIT and CIT correlated with neither BP nor HR responses. Conclusions: These results suggest that individual sensitivity and adaptability to tonic thermal pain is related to the intensity of initial pain rating and the latency to peak pain but not to cardiovascular responses.
    European journal of pain (London, England) 10/2015; DOI:10.1002/ejp.799 · 2.93 Impact Factor
    • "Several studies have shown positive relationships between CS pain intensity and CPM (van Wijk and Veldhuijzen, 2010), whilst others have been inconclusive (Pud et al., 2009). Granot et al. (2008) suggested a mild CS may evoke CPM, and it may be possible to elicit inhibitory effects on a TS using an innocuous CS (Treister et al., 2010). Lewis et al. (2012) found no difference in CPM effect size with greater CS pain intensity. "
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    ABSTRACT: People with chronic pain may exhibit pro-nociceptive phenotypes characterised partly by reduced conditioned pain modulation (CPM). Characterising variability in CPM in people with chronic low back pain (CLBP) may inform management. To investigate pro/anti-nociceptive effects of a CPM protocol in age/sex-matched healthy controls (HCs) and people with CLBP. Case-controlled trial (64 participants/group). The CPM protocol involved: test stimulus (TS) (noxious pressure applied by algometer to lumbar region); conditioning stimulus (CS) (noxious heat applied by thermode to dorsal hand). CPM recruitment was measured by the change in pain intensity (rated on a numeric rating scale (NRS)) of the TS in the presence and absence of the CS. Responses to this CPM protocol were variable for both groups with measures consistent with either inhibitory or facilitatory effects. A significantly greater proportion of facilitatory responses were seen in the CLBP cohort compared to HCs (73% versus 31%). In response to the CS, participants with CLBP demonstrated a mean increase in NRS scores (mean 1.3 points; p < 0.001), while HCs did not (mean -0.2 points; p = 0.35) and the between-group difference in change scores was significant (mean 1.4 points; p < 0.001; effect size (Hedges' g): 1.03). In HCs and participants with CLBP this CPM protocol elicited responses consistent with varying pro/anti-nociceptive effects. The higher proportion of participants with CLBP demonstrating a facilitatory response suggests a pro-nociceptive phenotype may characterise this cohort. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Manual therapy 03/2015; 101. DOI:10.1016/j.math.2015.02.011 · 1.71 Impact Factor
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    • "Several pilot trials before the start of the experiment had shown that it was not possible to maintain a constant pain intensity of 2/10 (mild pain) or 5/10 (moderate pain) with the tourniquet since a time-dependent pain intensity increase was noticed. Therefore, at the first study day, an individual-titrated CS (Granot et al., 2008) using a contact heat pain intensity of either 2/10 or 5/10, respectively, rated by the subjects on a 0–10 numerical pain rating scale (NRS; 0 indicated 'no pain' and 10 'worst imaginable pain intensity') was used. The CS was induced at two different time intervals, separated by a break of 30 min to the ventral part of the left (heat pain intensity 2/10 range: 37–44 °C, mean value: 39 ± 1 °C) or the right (heat pain intensity 5/10 range: 39–47 °C, mean value: 44 ± 2 °C) forearm, i.e., midway "
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    ABSTRACT: The aim was to investigate influence from variations in intensity of a painful conditioning stimulation (CS) on early (0-6 min) and prolonged (6-12 min) conditioned pain modulation (CPM) in volunteers during concurrent exposure to test stimuli (TS). CS was applied to either forearm using painful heat with an intensity of 2/10 and 5/10, respectively, rated on a 0-10 numerical pain rating scale. At a second session, CS with an intensity of 7/10 was applied to the arm using a tourniquet. Threshold and suprathreshold painful heat and pressure as well as painful repeated monofilament pricking (RMP) were assessed as TS. Regardless of TS, there was no significant difference in the magnitude of CPM within the same stimulus modality during the various intensities and phases of the CS. Significant modulation of heat pain thresholds (HPTs) was found during the early phase at 5/10 and 7/10, but not at 2/10. Only at 5/10 the prolonged CS resulted in a significant additional increase in HPT. During the early CS phase, CPM of suprathreshold heat pain was found at 2/10 and 5/10. The prolonged CS resulted in a significant additional temperature increase at 5/10. Only during the early phase significant CPM of pressure pain thresholds were found for all three pain intensities in conjunction with a significant CPM of suprathreshold pressure pain at 5/10. There was no CPM of RMP. The CS intensity and the duration of CPM modulated pain sensitivity differentially across TS modalities.
    European journal of pain (London, England) 07/2014; 18(6). DOI:10.1002/j.1532-2149.2013.00435.x · 2.93 Impact Factor
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