Pain
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Patients' expectations are important predictors of the outcome of analgesic treatments, as demonstrated predominantly in research on placebo effects. Three commonly investigated interventions that have been found to induce expectations (verbal suggestion, conditioning, and mental imagery) entail promising, brief, and easy-to-implement adjunctive procedures for optimizing the effectiveness of analgesic treatments. However, evidence for their efficacy stems mostly from research on experimentally evoked pain in healthy samples, and these findings might not be directly transferable to clinical populations. ⋯ Overall, a medium-sized effect of the interventions on patients' pain relief was observed (Hedges g = 0.61, I = 73%), with varying effects of verbal suggestion (k = 18, g = 0.75), conditioning (always paired with verbal suggestion, k = 3, g = 0.65), and imagery (k = 6, g = 0.27). Subset analyses indicated medium to large effects on experimental and acute procedural pain and small effects on chronic pain. In conclusion, patients' pain can be relieved with expectation interventions; particularly, verbal suggestion for acute procedural pain was found to be effective.
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Meta Analysis
Brain activations during pain: a neuroimaging meta-analysis of pain patients and healthy controls.
In response to recent publications from pain neuroimaging experiments, there has been a debate about the existence of a primary pain region in the brain. Yet, there are few meta-analyses providing assessments of the minimum cerebral denominators of pain. Here, we used a statistical meta-analysis method, called activation likelihood estimation, to define (1) core brain regions activated by pain per se, irrelevant of pain modality, paradigm, or participants and (2) activation likelihood estimation commonalities and differences between patients with chronic pain and healthy individuals. ⋯ Common activations for healthy subjects and patients with pain alike included the thalamus, ACC, insula, and cerebellum. A comparative analysis revealed that healthy individuals were more likely to activate the cingulum, thalamus, and insula. Our results point toward the central role of the insular cortex and ACC in pain processing, irrelevant of modality, body part, or clinical experience; thus, furthering the importance of ACC and insular activation as key regions for the human experience of pain.
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Review Meta Analysis
Effectiveness of psychological interventions for chronic pain on health care use and work absence: systematic review and meta-analysis.
Psychological interventions for chronic pain and its consequences have been shown to improve mood, disability, pain, and catastrophic thinking, but there has been no systematic review specifically of their effects on health care use or time lost from work as treatment outcomes in mixed chronic pain. We conducted a systematic review and meta-analysis to evaluate the effectiveness of psychological therapies for chronic pain (excluding headache) in adults for these outcomes. We used searches from 2 previous systematic reviews and updated them. ⋯ No benefits were found for medication reduction, but with less confidence in this result. Analysis of work loss showed no significant effects of psychological interventions over comparisons, but the use of many different metrics necessitated fragmenting the planned analyses, making summary difficult. The results are encouraging for the potential of routine psychological intervention to reduce posttreatment health care use, with associated cost savings, but it is likely that the range and complexity of problems affecting work necessitate additional intervention over standard group psychological intervention.
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Review Meta Analysis
The effect of bodily illusions on clinical pain: A systematic review and meta-analysis.
This systematic review and meta-analysis critically examined the evidence for bodily illusions to modulate pain. Six databases were searched; 2 independent reviewers completed study inclusion, risk of bias assessment, and data extraction. Included studies evaluated the effect of a bodily illusion on pain, comparing results with a control group/condition. ⋯ Conflicting results were found for virtual walking illusions (both active and inactive control comparisons). Single studies suggest no effect of resizing illusions on pain evoked by noxious stimuli, no effect of embodiment illusions, but a significant pain decrease with synchronous mirrored stroking in nonresponders to traditional mirror therapy. There is limited evidence to suggest that bodily illusions can alter pain, but some illusions, namely mirror therapy, bodily resizing, and use of functional prostheses show therapeutic promise.
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Review Meta Analysis
Meta-Analysis of Placebo Responses in Central Neuropathic Pain: Impact of Subject, Study, and Pain Characteristics.
The placebo response is a complex construct related to psychobiological effects, as well as natural history and regression to the mean. Moreover, patient and study design characteristics have also been proposed as significantly affecting placebo responses. The aim of the current investigation was to identify factors that contribute to variable placebo responses in clinical trials involving individuals with central neuropathic pain. ⋯ There were no significant effects for neurological condition (stroke vs multiple sclerosis vs spinal cord injury) or the type of intervention (eg, pharmacological vs noninvasive brain stimulation). In a planned subanalysis, the severity of damage in the spinal cord also had no significant effect on the placebo response. Further study is warranted to identify factors that may explain the impact of pain duration on the placebo response at the individual subject level.