Pain
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The experience of pain can be significantly influenced by expectancy (predictive cues). This ability to modulate pain has the potential to affect therapeutic analgesia substantially and constitutes a foundation for nonpharmacological pain relief. In this study, we investigated (1) brain regions involved in visual cue modulation of pain during anticipation of pain, pain administration, and pain rating; and (2) the association between pretest resting state functional connectivity and the magnitude of cue effects on pain ratings. ⋯ Functional magnetic resonance imaging results suggested that brain regions pertaining to the frontoparietal network (prefrontal and parietal cortex) and a pain/emotion modulatory region (rostral anterior cingulate cortex) are involved in cue modulation during both pain anticipation and administration stage. Most interestingly, we found that pretest resting state functional connectivity between the frontoparietal network (as identified by independent component analysis) and the rostral anterior cingulate cortex/medial prefrontal cortex was positively associated with cue effects on pain rating changes. We believe that these findings will shed new light on our understanding of variable cue/expectancy effects across individuals and how the intrinsic connectivity of the brain may influence expectancy-induced modulation of pain.
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The sexes differ with respect to perception of experimental pain. Anxiety influences pain perception more in men than in women; however, there lacks research exploring which anxiety constructs influence pain perception differentially between men and women. Furthermore, research examining whether depression is associated with pain perception differently between the sexes remains scant. ⋯ Depression was not systematically associated with pain perception in either sex. Systematic relationships were not identified that allow conclusions regarding how fear of pain, pain-related anxiety, and anxiety sensitivity may contribute to pain perception differentially in men and women; however, anxiety sensitivity was associated with increased pain tolerance, a novel finding needing further examination. The results provide directions for future research and clinical endeavors and support that fear and anxiety are important features associated with hyperalgesia in both men and women.
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Randomized Controlled Trial
Does neonatal morphine use affect neuropsychological outcomes at 8 to 9 years of age?
Morphine is widely used to treat severe pain in neonatal intensive care unit patients. Animal studies suggest adverse long-term side effects of neonatal morphine, but a follow-up study of 5-year-old children who participated in a morphine-placebo controlled trial as newborns found no such effects on the child's general functioning. This study indicated that morphine may negatively affect response inhibition, a domain of executive functions. ⋯ After adjustment for IQ and the propensity score, executive functioning as rated by the parents remained statistically significantly better in the morphine-treated group. The influence of the additional morphine given was not of a significant influence for any of the outcome variables. Overall, the present study demonstrates that continuous morphine infusion of 10 μg/kg/h during the neonatal period does not harm general functioning and may even have a positive influence on executive functions at 8 to 9 years.
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Context can influence the experience of any event. For instance, the thought that "it could be worse" can improve feelings towards a present misfortune. In this study we measured hedonic feelings, skin conductance, and brain activation patterns in 16 healthy volunteers who experienced moderate pain in two different contexts. ⋯ Furthermore, the change in outcome hedonics correlated with activity in the periacqueductal grey (PAG) of the descending pain modulatory system (DPMS). The context manipulation also significantly increased functional connectivity between reward circuitry and the PAG, consistent with a functional change of the DPMS due to the altered motivational state. The findings of this study point to a role for brainstem and reward circuitry in a context-induced "hedonic flip" of pain.
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The aim of this study was to examine whether irritable bowel syndrome (IBS) is associated with increased somatic pain sensitivity in a large population-based sample and to test whether this association was independent of sex, age, comorbid chronic pain, and psychological distress. Pain sensitivity tests included assessment of heat-pain threshold (N=4054) and pressure-pain threshold (N=4689) and of cold-pressor pain intensity and tolerance (N=10,487). Cox regression and analysis of variance (ANOVA) were used to assess the relationship between IBS and pain sensitivity in stepwise multivariate models. ⋯ Results for pressure-pain threshold were not significant. Heat- and cold-pressor pain sensitivity was greatest for the IBS reporting severe chronic abdominal pain, indicating that hyperalgesia in IBS is related to degree of clinical pain rather than to the diagnosis per se. Because all pain tests were all carried out on the upper extremities, our findings indicate the presence of widespread hyperalgesia in IBS, which may be a contributing factor to the high rate of comorbid pain seen in this patient group.