Pain
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Opioid therapy offers the promise of reducing the burden of chronic pain in not just individual patients, but among the broad population of patients with chronic pain. Randomized trials have demonstrated that opioid therapy for up to 12-16weeks is superior to placebo, but have not addressed longer-term use. In the United States, opioid sales have quadrupled during 2000-2010, with parallel increases in opioid accidental overdose deaths and substance abuse admissions. ⋯ Long-term opioid therapy appears to be associated with iatrogenic harm to the patients who receive the prescriptions and to the general population. The United States has, in effect, conducted an experiment of population-wide treatment of chronic pain with long-term opioid therapy. The population-wide benefits have been hard to demonstrate, but the harms are now well demonstrated.
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Chemotherapy-induced neuropathy (CIN) is an adverse effect of chemotherapy. Pain in CIN might comprise neuropathic and nonneuropathic (ie, musculoskeletal) pain components, which might be characterized by pain patterns, electrophysiology, and somatosensory profiling. Included were 146 patients (100 female, 46 male; aged 56 ± 0.8 years) with CIN arising from different chemotherapy regimens. ⋯ The detrimental effect of chemotherapy on large fibres failed to differentiate painful from painless CIN. Patients stratified for musculoskeletal or neuropathic pain, however, differed in psychological and somatosensory parameters. This stratification might allow for the application of a more specific therapy.
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Recent research suggests that exercise can be effective in reducing pain in animals and humans with neuropathic pain. To investigate mechanisms in which exercise may improve hyperalgesia associated with prediabetes, C57Bl/6 mice were fed either standard chow or a high-fat diet for 12 weeks and were provided access to running wheels (exercised) or without access (sedentary). The high-fat diet induced a number of prediabetic symptoms, including increased weight, blood glucose, and insulin levels. ⋯ These results confirm that elevated hypersensitivity and associated neuropathic changes can be induced by a high-fat diet and exercise may alleviate these neuropathic symptoms. These findings suggest that exercise intervention could significantly improve aspects of neuropathy and pain associated with obesity and diabetes. Additionally, this work could potentially help clinicians determine those patients who will develop painful versus insensate neuropathy using intraepidermal nerve fiber quantification.
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Hundreds of genes are proposed to contribute to nociception and pain perception. Historically, most studies of pain-related genes have examined them in isolation or alongside a handful of other genes. More recently the use of systems biology techniques has enabled us to study genes in the context of the biological pathways and networks in which they operate. ⋯ The Web site can be used to find out more about a gene of interest by looking at the function of its interaction partners. It can also be used to interpret the results of a functional genomics experiment by revealing putative novel pain-related genes that have similar expression patterns to known pain-related genes and by ranking genes according to their network connections with known pain genes. We expect this resource to grow over time and become a valuable asset to the pain community.