Pain
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Randomized Controlled Trial
A population-based study of the use of chronic pain and opioids in Portugal.
Although increasing doubts exist regarding the long-term effectiveness and safety of opioids in patients with chronic pain (CP), most guidelines still recognize opioids as an option in effective management of CP. We aimed to describe the prevalence and factors associated with opioid use in subjects with CP in Portugal and to evaluate satisfaction and self-assessed treatment effectiveness. A nationwide study was conducted in a representative sample of the adult Portuguese population. ⋯ Indeed, we showed that in Portugal, as in many other regions in the world, opioids are used much less frequently than in those few countries. Moreover, we did not find significant differences among users and nonusers of opioids regarding satisfaction and self-assessed effectiveness, eventually showing the results to be in line with reports that show doubt about opioids' effectiveness. Further research and particular attention to and continuous monitoring of the trends of use and abuse of opioids worldwide are recommended.
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Patients with low back pain (LBP; N = 102), fibromyalgia (FM; N = 100), and headache (HA; N = 100) were asked to describe their pain in their own words, and the words and phrases they used were then classified into 7 global domains (eg, Pain Quality, Pain Magnitude) and as many specific subdomains as needed to capture all of the ideas expressed (eg, under Pain Quality, subdomains such as sharp, achy, and throbbing). Fifteen pain quality subdomains were identified as most common. Nine of these demonstrated significant between-group differences in frequency. ⋯ The findings are generally consistent with a study that used similar procedures in other patient samples to identify the most common words patients use to describe pain, supporting their generalizability. The findings also support the use of pain quality measures for discriminating between chronic pain conditions. Finally, the findings have important implications for evaluating and modifying pain quality measures as needed.
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Although individual reports suggest that baseline morphometry or activity of transversus abdominis or lumbar multifidus predict clinical outcome of low back pain (LBP), a related systematic review is unavailable. Therefore, this review summarized evidence regarding the predictive value of these muscular characteristics. Candidate publications were identified from 6 electronic medical databases. ⋯ There was conflicting evidence for a relation between baseline percent thickness change of lumbar multifidus during contraction and the clinical outcomes of patients after various conservative treatments. Given study heterogeneity, the small number of included studies and the inability of conventional greyscale B-mode ultrasound imaging to measure muscle activity, our findings should be interpreted with caution. Further large-scale prospective studies that use appropriate technology (ie, electromyography to assess muscle activity) should be conducted to investigate the predictive value of morphometry or activity of these muscles with respect to LBP-related outcomes measures.
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Individuals with spinal cord injury (SCI) often have chronic pain, which may have a major impact on their quality of life. The purpose of this article is to present an update on the classification of SCI pain, recent advances in the understanding of underlying mechanisms, and current evidence-based treatment of SCI pain. ⋯ We need to improve preclinical assessment of pain-like behavior in central pain models, and improve the clinical assessment of pain and our understanding of the interaction with cognitive, emotional, and social factors. In future studies on mechanisms and treatment, we need to acknowledge the different phenotypes of chronic SCI pain.
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Activation of glial cells and neuro-glial interactions are emerging as key mechanisms underlying chronic pain. Accumulating evidence has implicated 3 types of glial cells in the development and maintenance of chronic pain: microglia and astrocytes of the central nervous system (CNS), and satellite glial cells of the dorsal root and trigeminal ganglia. Painful syndromes are associated with different glial activation states: (1) glial reaction (ie, upregulation of glial markers such as IBA1 and glial fibrillary acidic protein (GFAP) and/or morphological changes, including hypertrophy, proliferation, and modifications of glial networks); (2) phosphorylation of mitogen-activated protein kinase signaling pathways; (3) upregulation of adenosine triphosphate and chemokine receptors and hemichannels and downregulation of glutamate transporters; and (4) synthesis and release of glial mediators (eg, cytokines, chemokines, growth factors, and proteases) to the extracellular space. ⋯ Glial activation also occurs in acute pain conditions, and acute opioid treatment activates peripheral glia to mask opioid analgesia. Thus, chronic pain could be a result of "gliopathy," that is, dysregulation of glial functions in the central and peripheral nervous system. In this review, we provide an update on recent advances and discuss remaining questions.