Pain
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Review Meta Analysis
Neuropathic pain clinical trials: factors associated with decreases in estimated drug efficacy.
Multiple recent pharmacological clinical trials in neuropathic pain have failed to show beneficial effect of drugs with previously demonstrated efficacy, and estimates of drug efficacy seems to have decreased with accumulation of newer trials. However, this has not been systematically assessed. Here, we analyze time-dependent changes in estimated treatment effect size in pharmacological trials together with factors that may contribute to decreases in estimated effect size. ⋯ Several factors that changed over time, such as larger study size, longer study duration, and more studies reporting 50% or 30% pain reduction, correlated with the decrease in estimated drug effect sizes. This suggests that issues related to the design, outcomes, and reporting have contributed to changes in the estimation of treatment effects. These factors are important to consider in design and interpretation of individual study data and in systematic reviews and meta-analyses.
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Randomized Controlled Trial
Efficacy of adding interoceptive exposure to intensive interdisciplinary treatment for adolescents with chronic pain: a randomized controlled trial.
Fear of pain plays an important role in the maintenance of chronic pain. It may be reduced through exposure therapy. This 2-arm parallel samples randomized controlled trial aimed to investigate whether interoceptive exposure (IE) therapy enhances reductions in fear of pain (primary outcome), pain (pain intensity, pain-related disability, and school absence), and emotional characteristics (anxiety and catastrophizing) when implemented as an adjunctive treatment in the context of intensive interdisciplinary pain treatment for pediatric chronic pain patients. ⋯ There were no greater decreases in the IE group (P > 0.1). The exploratory analyses revealed that the patients with high fear of pain before treatment (P < 0.05, (Equation is included in full-text article.)> 0.03) and the patients with abdominal pain (P < 0.04, (Equation is included in full-text article.)> 0.25) showed greater decreases in their fear of pain (total and subscale score) in the IE group than in the RT group. In conclusion, the results suggest that IE is not particularly effective for all the pediatric chronic pain patients, but the patients with high fear of pain before treatment and with abdominal pain strongly benefit from this intervention.
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Randomized Controlled Trial
Aδ and not C fibers mediate thermal hyperalgesia to short laser stimuli after burn injury in man.
It remains unclear which nerve fibers are responsible for mediating hyperalgesia after skin injury. Here, we examined the role of Aδ and C fibers in inflammatory hyperalgesia after a first-degree burn injury. A CO2 laser delivered ultrafast short constant-temperature heat pulses to the upper part of the lower leg to stimulate selectively the relatively fast-conducting thinly myelinated Aδ and the slowly conducting unmyelinated C fibers. ⋯ No group differences in C-fiber-mediated sensations were observed. Our findings indicate that quickly adapting Aδ fibers but not quickly adapting C fibers are sensitized when activated by short and ultrafast heat stimuli after skin burn injury. Our results further show that this change occurs between 1 hour and 24 hours after injury and that it does not extend to the skin surrounding the injury.
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After traumatic exposure, individuals are at risk of developing symptoms of both pain and post-traumatic stress disorder (PTSD). Theory and research suggest a complex and potentially mutually maintaining relationship between these symptomatologies. However, findings are inconsistent and the applied methods are not always well suited for testing mutual maintenance. ⋯ In addition, the synthesis suggested that hyperarousal and intrusion symptoms may be of particular importance in these cross-lagged relationships, while there was inconclusive evidence of catastrophizing as a mediator. In conclusion, the findings suggest an entangled, but not necessarily mutually maintaining relationship between pain and PTSD symptomatology. However, major variations in findings and methodologies complicated synthesis, prompting careful interpretation and heightening the likelihood that future high-quality studies will change these conclusions.
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Pain is a prevalent and debilitating symptom of multiple sclerosis (MS); yet, the mechanisms underlying this pain are unknown. Previous studies have found that the functional relationships between the salience network (SN), specifically the right temporoparietal junction a SN node, and other components of the dynamic pain connectome (default mode network [DMN], ascending and descending pathways) are abnormal in many chronic pain conditions. ⋯ We found that (1) ∼50% of our patients had NP features, (2) abnormalities in SN-DMN sFC were driven by the mixed-neuropathic subgroup, (3) in patients with mixed NP, dFC measures showed that there was a striking change in how the SN was engaged with the ascending nociceptive pathway and descending modulation pathway, (4) BOLD variability was increased in the DMN, and (5) the degrees of sFC and BOLD variability abnormalities were related to pain interference. We propose that abnormal SN-DMN cross-network FC and temporal dynamics within and between regions of the dynamic pain connectome reflect MS pain features.