Pain additivity, diffuse noxious inhibitory controls, and attention: A functional measurement analysis

Physiological Psychology, Otto-Friedrich University, Bamberg, Germany.
Somatosensory and Motor Research (Impact Factor: 0.64). 01/2008; 24(4):189-201. DOI: 10.1080/08990220701637638
Source: PubMed


This study utilized the methodology of Functional Measurement theory to investigate the additivity of painful and non-painful thermally induced experiences at one body site with those produced by brief noxious and innocuous electrical stimuli at another. Forty healthy young subjects were tested, using a Peltier thermode to induce tonic pain and an electrocutaneous stimulator for presenting phasic pain, under conditions of either full attention or visual/cognitive distraction (counting numerous light signals) in order to evaluate whether the summed effects are attributable to refocused attention. Six levels of intensity were combined in a factorial design for both tonic and phasic pain. Subjects indicated the overall strength of their dual perception on a visual analog scale. Stimuli showed complex patterns of interaction. Two stimuli were generally rated as greater than one, but the summation was far from additive and greatly influenced by the intensity of the stronger stimulus, suggesting inhibitory action. In general, tonic heat pain strongly affected the perception of phasic electrocutaneous pain whereas the reverse was only partly true. Distraction had a very small effect, suggesting that the "pain inhibits pain" phenomenon attributable to diffuse noxious inhibitory controls (DNIC) is not due to attentional processes. Our data also relate to issues regarding spatial summation across dermatomes and to adaptation level effects in pain, in which a strong painful experience serves as an anchor or comparison point by which others are judged. The psychophysical findings provide a perceptual foundation for clinical phenomena in which patients face with comorbid pain disorders.

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Available from: Stefan Lautenbacher
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    • "Most relevant to the present study, some investigations have also assessed the contribution of distraction to HNCS analgesia. These studies yielded conflicting results but generally suggest that HNCS analgesia is independent of distraction, although it may be modulated by attentional processes in some conditions [10] [18] [22] [24] [29] [39] (see also [44] for review). For instance, in paradigms involving directed attention, some studies reported no effect of attention focussing on HNCS analgesia [22], some reported increased analgesia with attention focussing on HNCS [15], and others observed some effect of attention focussing in fibromyalgia patients but not in healthy volunteers [38]. "
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    ABSTRACT: Heterotopic noxious counterstimulation (HNCS) by the application of a sustained noxious stimulus has been shown to inhibit nociceptive processes and decrease pain induced by a competing noxious stimulus. However, it is still not clear how attentional processes contribute to these effects. The main objective of this study was to compare the analgesic effects of HNCS in 2 sessions during which top-down attention was manipulated. Acute shock pain and the nociceptive flexion reflex were evoked by transcutaneous electrical stimulations of the right sural nerve in 4 blocks (15 stimuli/block): baseline, heterotopic innocuous counterstimulation (HICS), HNCS, and recovery. Counterstimulation was applied on the left upper limb with a thermode (HICS) or a cold pack (HNCS). Attention was manipulated between sessions by instructing participants to focus their attention on shock pain or counterstimulation. Shock pain ratings decreased significantly during counterstimulation (P<.001) with stronger effects of HNCS vs HICS in both sessions (P<.01). Furthermore, shock pain inhibition during HNCS relative to baseline was stronger with attention focusing on counterstimulation compared to attention focusing on shocks (P = .015). However, the relative decrease in pain ratings during HNCS vs HICS was not significantly affected by the direction of attention (P = .7). As for spinal nociceptive processes, nociceptive flexion reflex amplitude was significantly decreased during counterstimulation (P<.001) with larger reductions during HNCS compared to HICS (P = .03). However, these effects were not altered by attention (P = .35). Together, these results demonstrate that top-down attention and HNCS produce additive analgesic effects. However, attentional modulation of HNCS analgesia seems to depend on supraspinal processes.
    Full-text · Article · Jun 2012 · Pain
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    • "Distraction is an effective stimulus to diminish pain and frequently used as a pain coping strategy (Keogh et al., 2000), and while it has often been questioned whether pain inhibition in response to an additional painful stimuli is simply due to a distraction process, recent evidence supports that the mechanisms through which additional pain or distraction inhibit pain are largely separable. (Moont et al., 2010; Lautenbacher et al., 2007). Thus, our findings indicate that the unresponsiveness of the pain-inhibitory system when directly challenged is independent of the stimulus used to trigger the system (e.g., pain or distraction). "
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    ABSTRACT: Sleep of good quantity and quality is considered a biologically important resource necessary to maintain homeostasis of pain-regulatory processes. To assess the role of chronic sleep disturbances in pain processing, we conducted laboratory pain testing in subjects with primary insomnia. Seventeen participants with primary insomnia (mean ± SEM 22.6 ± 0.9 yrs, 11 women) were individually matched with 17 healthy participants. All participants wore an actigraph device over a 2-week period and completed daily sleep and pain diaries. Laboratory pain testing was conducted in a controlled environment and included (1) warmth detection threshold testing, (2) pain sensitivity testing (threshold detection for heat and pressure pain), and (3) tests to access pain modulatory mechanisms (pain facilitation and inhibition). Primary insomnia subjects reported experiencing spontaneous pain on twice as many days as healthy controls during the at-home recording phase (p < 0.05). During laboratory testing, primary insomnia subjects had lower pain thresholds than healthy controls (p < 0.05 for heat pain detection threshold, p < 0.08 for pressure pain detection threshold). Unexpectedly, pain facilitation, as assessed with temporal summation of pain responses, was reduced in primary insomnia compared to healthy controls (p < 0.05). Pain inhibition, as assessed with the diffuse noxious inhibitory control paradigm (DNIC), was attenuated in insomnia subjects when compared to controls (p < 0.05). Based on these findings, we propose that pain-inhibitory circuits in patients with insomnia are in a state of constant activation to compensate for ongoing subclinical pain. This constant activation ultimately may result in a ceiling effect of pain-inhibitory efforts, as indicated by the inability of the system to adequately function during challenge.
    Preview · Article · Apr 2012 · European journal of pain (London, England)
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    • "The magnitude of CPM is calculated as the decrease in phasic pain observed during concurrent administration of the tonic conditioning stimulus. Studies that have examined the relationship between attention and CPM on pain outcomes have shown that the " pain inhibiting pain " phenomenon attributable to CPM is not dependent upon distraction (Lautenbacher et al., 2007; Moont et al., 2010). The analgesic effect of CPM in humans is thought to be produced by supraspinally-generated inhibition of wide dynamic range (Cadden, 1993) and nociceptive-specific (Hu, 1990) neurons. "
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    ABSTRACT: Greater dispositional optimism has been related to less severe pain; however, whether optimism is associated with endogenous pain modulation has not yet been examined. The beneficial effects of dispositional optimism often vary according to cultural dynamics. Thus, assessing optimism-pain relationships across different ethnic groups is warranted. This study sought to examine the association between optimism and conditioned pain modulation (CPM), and test whether this association differs according to ethnicity. Optimism and CPM were assessed in a sample of healthy, ethnically diverse young adults. CPM was determined by comparing pressure pain thresholds obtained before and during exposure to a cold pressor task. All participants completed a validated measure of dispositional optimism. Greater reported optimism was significantly associated with enhanced CPM, and the strength of this association did not vary according to individuals' ethnic background. These findings suggest that an optimistic disposition may potentiate endogenous pain inhibition.
    Full-text · Article · Feb 2012 · Journal of Behavioral Medicine
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