European journal of pain : EJP
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Fixed-dose combination analgesics are used widely, and available both on prescription and over-the-counter. Combination drugs should provide more analgesia than with any single drug in the combination, but there is no evidence in humans about whether oral combinations have just additive effects, or are synergistic or even subadditive. We suggest that the measured result for the combination would be the summation of the absolute benefit increase (effect of active drug minus effect of placebo) of each component of a combination if effects were (merely) additive, and greater than the sum of the absolute benefits if they were synergistic. ⋯ Results showed that expected numbers needed to treat (NNT) for additive effects were generally within the 95% confidence interval of measured NNTs. This was true for combinations of paracetamol plus ibuprofen and paracetamol plus opioids in acute pain, and naproxen plus sumatriptan in migraine, but not where efficacy was very low or very high, nor combinations of paracetamol plus dextropropoxyphene. There was no evidence of synergy, defined as supra-additive effects.
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Sleep of good quantity and quality is considered a biologically important resource necessary to maintain homeostasis of pain-regulatory processes. To assess the role of chronic sleep disturbances in pain processing, we conducted laboratory pain testing in subjects with primary insomnia. Seventeen participants with primary insomnia (mean ± SEM 22.6 ± 0.9 yrs, 11 women) were individually matched with 17 healthy participants. ⋯ Pain inhibition, as assessed with the diffuse noxious inhibitory control paradigm (DNIC), was attenuated in insomnia subjects when compared to controls (p < 0.05). Based on these findings, we propose that pain-inhibitory circuits in patients with insomnia are in a state of constant activation to compensate for ongoing subclinical pain. This constant activation ultimately may result in a ceiling effect of pain-inhibitory efforts, as indicated by the inability of the system to adequately function during challenge.
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Multicenter Study
Using graded motor imagery for complex regional pain syndrome in clinical practice: failure to improve pain.
There is good evidence from studies conducted in a single-centre research setting for the efficacy of graded motor imagery (GMI) treatment, a complex physiotherapy intervention, to reduce pain in long-standing complex regional pain syndrome (CRPS). However, whether GMI is effective in clinical practice is not established. ⋯ The failure of our real-world implementation of GMI suggests that better understanding of both the GMI methodology and its interaction with other treatment methods is required to ensure that GMI research results can be translated into clinical practice. Our results highlight challenges with the translation of complex interventions for chronic pain conditions into clinical practice.
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The fundamental aspects of bone associated pain in humans are not fully understood. In this study pressure pain applied to the tibia bone was investigated experimentally in humans and by means of computer simulations. In humans, the pressure pain sensitivity and the relation between tissue indentation and pressure intensity were recorded by a computer-controlled pressure algometer with two different probe sizes (0.03 cm(2) and 1.0 cm(2)). ⋯ For both probes the strain peaked in adipose tissue at 0.29, and in the bone interface it was reduced by 3% (0.03 cm(2)) and 15% (1.0 cm(2)), respectively. For both probes the stress peaked at 235 kPa in skin layer, and in the deeper layers it was reduced to 50 kPa. Mechanosensitive nociceptors innervating the periosteum are ideally placed to mediate pain evoked by pressure stimulation on the tibia bone and small diameter probes may be optimal for assessing bone associated pain sensitivity.
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Widespread pain (WSP) is common in the general population and is associated with poor outcomes. The aim of this study was to quantify the risk for medically certified disability pension from WSP. We further studied how other common physical symptoms, common mental disorders and functional limitations influenced this risk. ⋯ Further adjustments for other common symptoms, including mental illness, reduced, but did not abolish these risks. WSP is a major risk factor for disability pensions, and not only pensions for musculoskeletal disorders. The global impact of WSP, and its close association to other symptoms, suggests prevention of the severe occupational outcomes for this group must have a broad focus and move beyond symptom directed approaches.