European journal of pain : EJP
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Painful diabetic polyneuropathy is a common complication of diabetes mellitus. Drug therapies are ineffective in many patients. Therefore other treatment modalities should be considered, including spinal cord stimulation. We performed a systematic review to evaluate treatment efficacy and safety of spinal cord stimulation in painful diabetic polyneuropathy. SEARCH STRATEGY AND SELECTION CRITERIA: A systematic search with reference tracing was conducted in Pubmed and Embase from January 1980 to March 2010 to determine possible eligible articles. Reports were identified using the following keywords: (1) "diabetic neuropathies" AND "electric stimulation"; (2) "diabetic neuropathies" AND "spinal cord" and (3) "pain" AND "electric stimulation" AND "spinal cord". Subsequently, data were recruited on the efficacy and safety of spinal cord stimulation in this disorder. ⋯ Available literature shows promising results for the pain-relieving effect of spinal cord stimulation in painful diabetic polyneuropathy. The outcome of a randomized clinical trial is needed before spinal cord stimulation can be considered to be integrated in the standardized treatment algorithm.
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Activation of the prefrontal cortex occurs during acute and chronic pain and models of experimental hyperalgesia. The present study was carried out to determine possible miRNA changes in the prefrontal cortex, after inflammatory pain induced by facial carrageenan injection in mice. miRNA microarray analyses showed significantly increased levels of miR-155 and miR-223 in the prefrontal cortex of carrageenan-injected mice. The changes were verified by real-time RT-PCR, and shown to occur bilaterally. ⋯ Significantly downregulated c/ebp Beta but upregulated GCSF, accompanied by increased immunolabeling with an antibody to myeloperoxidase were found in the prefrontal cortex of facial carrageenan treated mice. It is postulated that this could lead to increased inflammation and activation of the prefrontal cortex. Further studies are necessary to determine if specific miRNAs could be useful as therapeutic molecules for pain.
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Comparative Study Clinical Trial
Attenuation of experimental pain by vibro-tactile stimulation in patients with chronic local or widespread musculoskeletal pain.
Patients with chronic pain syndromes, like fibromyalgia (FM) complain of widespread pain and tenderness, as well as non-refreshing sleep, cognitive dysfunction, and negative mood. Several lines of evidence implicate abnormalities of central pain processing as contributors for chronic pain, including dysfunctional descending pain inhibition. One form of endogenous pain inhibition, diffuse noxious inhibitory controls (DNIC), has been found to be abnormal in some chronic pain patients and evidence exists for deficient spatial summation of pain, specifically in FM. Similar findings have been reported in patients with localized musculoskeletal pain (LMP) disorders, like neck and back pain. Whereas DNIC reduces pain through activation of nociceptive afferents, vibro-tactile pain inhibition involves innocuous A-beta fiber. To assess whether patients with localized or widespread chronic pain disorders have dysfunctional A-beta related pain inhibition we enrolled 28 normal pain-free controls (NC), 29 FM patients, and 19 subjects with neck or back pain. All received 10s sensitivity-adjusted noxious heat stimuli to the forearms as test stimuli. To assess endogenous analgesic mechanisms of study subjects, vibro-tactile conditioning stimuli were simultaneously applied with test stimuli either homotopically or heterotopically. Additionally, the effect of distraction on experimental pain was assessed. Homotopic vibro-tactile stimulation resulted in 40% heat pain reductions in all subject groups. Distraction did not seem to affect experimental pain ratings. ⋯ Vibro-tactile stimulation effectively recruited analgesic mechanisms not only in NC but also in patients with chronic musculoskeletal pain, including FM. Distraction did not seem to contribute to this analgesic effect.
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Although many studies have investigated the effectiveness of distraction as a method of pain control, the cognitive processes by which attentional re-direction is achieved, remain unclear. In this study the role of executive functioning abilities (inhibition, task switching and working memory) in the effectiveness of distraction is investigated. We hypothesized that the effectiveness of distraction in terms of pain reduction would be larger in participants with better executive functioning abilities. ⋯ Participants were randomly assigned to (1) a distraction group, in which an attention-demanding tone-detection task was performed during the CPT, or (2) a control group, in which no distraction task was performed. Participants in the distraction group reported significantly less pain during the CPT, but the pain experience was not influenced by executive functioning abilities. However, the performance on the distraction task improved with better inhibition abilities, indicating that inhibition abilities might be important in focussing on a task despite the pain.
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Small fibre neuropathy supposedly causes pain in Fabry patients, but the relationship between small nerve fibre function and pain severity is unclear. ⋯ In Fabry disease, no linear relationship exists between pain and small nerve fibre function. With older age and more severe disease pain may abate as nerve fibre function further deteriorates.