The journal of pain : official journal of the American Pain Society
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Dorsal root ganglion stimulation (DRGS) is a neuromodulation therapy for chronic pain that is refractory to conventional medical management. Currently, the mechanisms of action of DRGS-induced pain relief are unknown, precluding both our understanding of why DRGS fails to provide pain relief to some patients and the design of neurostimulation technologies that directly target these mechanisms to maximize pain relief in all patients. ⋯ Here, we summarize the leading hypotheses of the mechanisms of DRGS-induced analgesia, and propose areas of future study that will be vital to improving the clinical implementation of DRGS. PERSPECTIVE: This article synthesizes the evidence supporting the current hypotheses of the mechanisms of action of DRGS for chronic pain and suggests avenues for future interdisciplinary research which will be critical to fully elucidate the analgesic mechanisms of the therapy.
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Determining the mechanistic causes of complex biopsychosocial health conditions such as low back pain (LBP) is challenging, and research is scarce. Cross-sectional studies demonstrate altered excitability and organization of the somatosensory and motor cortex in people with acute and chronic LBP, however, no study has explored these mechanisms longitudinally or attempted to draw causal inferences. Using sensory evoked potential area measurements and transcranial magnetic stimulation derived map volume we analyzed somatosensory and motor cortex excitability in 120 adults experiencing acute LBP. ⋯ These data provide evidence that low somatosensory cortex excitability in the acute stage of LBP is a cause of chronic pain. PERSPECTIVE: This prospective longitudinal cohort study design identified low sensorimotor cortex excitability during the acute stage of LBP in people who developed chronic pain. Interventions that target this proposed mechanism may be relevant to the prevention of chronic pain.
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Pain appraisals are closely tied to pain and functional outcomes. Pain-related injustice and pain catastrophizing appraisals have both been identified as important cognitive-emotional factors in the pain experience of youth. Although pain-related injustice and catastrophizing have been linked to worse pain outcomes - as primary predictors and intermediary variables - little is known about whether they operate as independent or parallel mediators of the relationship between pain and functioning in youth. ⋯ The findings suggest these pain-related appraisals play different intermediary roles in the relationships among pain and future psychosocial outcomes. PERSPECTIVE: Pain-related injustice and catastrophizing appraisals play different intermediary roles in the relationships among pain and future psychosocial outcomes in youth with chronic pain. Treatments targeting pain-related injustice appraisals in pediatric populations are needed to complement existing treatments for catastrophizing.
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Randomized Controlled Trial
Reframe the Pain: A Randomized Controlled Trial of a Parent-Led Memory-Reframing Intervention.
Negatively-biased pain memories (ie, recalling more pain as compared to earlier reports) are a robust predictor of future pain experiences. This randomized controlled trial examined the efficacy of a memory-reframing intervention to reframe children's pain memories. Sixty-five children (54% girls, Mage=5.35 years) underwent a tonsillectomy and reported their levels of post-surgical pain intensity and pain-related fear. 2 weeks post-surgery, children and 1 of their parents were randomized to the memory-reframing intervention or control group. ⋯ Clinicaltrials.gov:NCT03538730. PERSPECTIVE: This article presents results of the first randomized controlled trial examining the efficacy of parent-led memory-reframing intervention to change children's memories for pain. Children of parents who were taught and engaged in optimal reminiscing about a past surgery experience remembered their pain intensity more accurately/positively.
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Randomized Controlled Trial
Producing clinically meaningful reductions in disability: A causal mediation analysis of a patient education intervention.
Patient education is recommended as first-line care for low back pain (LBP), although its efficacy for providing clinically meaningful reductions in disability has been questioned. One way to improve treatment effects is to identify and improve targeting of treatment mechanisms. We conducted a pre-planned causal mediation analysis of a randomized, placebo-controlled trial investigating the effectiveness of patient education for patients with acute LBP. 202 patients who had fewer than six-weeks' duration of LBP and were at high-risk of developing chronic LBP completed two, one-hour treatment sessions of either intensive patient education, or placebo patient education. 189 participants provided data for the outcome self-reported disability at three-months and the mediators, pain self-efficacy, pain catastrophizing, and back beliefs at one-week post treatment. ⋯ Considering the mediator-outcome relationship, patient education would need to induce an 8 point difference on the pain self-efficacy questionnaire (0-60); an 11 point difference on the back beliefs questionnaire (9-45); and a 21 point difference on the pain catastrophizing scale (0-52) to achieve a minimally clinically important difference of 2 points on the Roland Morris Disability Questionnaire (0-24). PERSPECTIVE: Understanding the mechanisms of patient education can inform how this treatment can be adapted to provide clinically meaningful reductions in disability. Our findings suggest that adapting patient education to better target back beliefs and pain self-efficacy could result in clinically meaningful reductions in disability whereas the role of pain catastrophizing in acute LBP is less clear.