Pain
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Development and application of psychophysical test paradigms to assess endogenous pain modulation in healthy controls and in patients yielded large body of data over the last 2 decades. These tests can assist in predicting pain acquisition, in characterizing pain syndromes and related dysfunctions of pain modulation, and in predicting response to treatment. This chapter reviews the development of thought on pain modulation in the clinical setup, focusing on conditioned pain modulation, and update on accumulated data regarding the mechanism, protocols of administration, and applications in the clinic.
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Research into complex regional pain syndrome (CRPS) has made significant progress. First, there was the implementation of the official IASP "Budapest" diagnostic criteria. It would be desirable to also define exclusion and outcome criteria that should be reported in studies. ⋯ In an attempt to avoid pain, patients neglect their limb and learn maladaptive nonuse. The final step will be to assess large cohorts and to analyze these data together with data from public resources using a bioinformatics approach. We could then develop diagnostic toolboxes for individual pathophysiology and select focused treatments or develop new ones.
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Randomized Controlled Trial
Trajectories of Change During a Randomized Controlled Trial of Internet-delivered Psychological Treatment for Adolescent Chronic Pain: How does Change in Pain and Function Relate?
Although pain and function improve at immediate posttreatment for youth receiving cognitive behavioral therapy for chronic pain, limited data are available to understand changes that youth make during psychological treatment. We sought to characterize distinct trajectory patterns of change in pain and function to understand the temporal association of these changes during internet-delivered cognitive behavioral therapy (CBT). Weekly repeated assessments of pain and function were conducted during 8 weeks of treatment among 135 adolescents, aged 11 to 17 years, with chronic pain who were randomized to the cognitive behavioral intervention arm of an ongoing trial of internet-delivered CBT (Web-based management of adolescent pain; Web-MAP2). ⋯ There was no support for improvements in either pain or function to precede changes in the other domain. Findings may be useful in informing future studies of psychosocial treatments for pediatric chronic pain to consider how to target treatment strategies to distinct patient response profiles. This may lead to the development of intervention strategies that can both more effectively target children's pain and function during treatment and lead to sustained changes after treatment.
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Fear and avoidance have been consistently associated with poor pain-related outcomes in children. In the context of the pediatric pain experience, parent distress and behaviors can be highly influential. This study validated the Parent Fear of Pain Questionnaire (PFOPQ) to assess a parent's fears and avoidance behaviors associated with their child's pain. ⋯ In testing the IFAM, parent behavior contributed directly and indirectly to child avoidance, whereas parent fear and catastrophizing contributed indirectly to child avoidance through parent behavior and child fear and catastrophizing, in turn, influencing child functional disability levels. This study provides the first measure of parent pain-related fears and avoidance behaviors and evaluates the theorized IFAM. These results underscore the important influence of parents on child pain-related outcomes and put forth a psychometrically sound measure to assess parent fear and avoidance in the context of their child's pain.
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Neuropathic pain (NP) is a significant medical and socioeconomic burden. Epidemiological surveys have indicated that many patients with NP do not receive appropriate treatment for their pain. A number of pharmacological agents have been found to be effective in NP on the basis of randomized controlled trials including, in particular, tricyclic antidepressants, serotonin and norepinephrine reuptake inhibitor antidepressants, pregabalin, gabapentin, opioids, lidocaine patches, and capsaicin high-concentration patches. ⋯ However, meta-analyses indicate that only a minority of patients with NP have an adequate response to drug therapy. Several reasons may account for these findings, including a modest efficacy of the active drugs, a high placebo response, the heterogeneity of diagnostic criteria for NP, and an inadequate classification of patients in clinical trials. Improving the current way of conducting clinical trials in NP could contribute to reduce therapeutic failures and may have an impact on future therapeutic algorithms.