European journal of pain : EJP
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Evaluating potentially analgesic effects of drugs and various treatments is critically dependent on valid animal models of pain. Since primary somatosensory (SI) cortex is likely to play an important role in processing sensory aspects of pain, we here assess whether monitoring SI cortex nociceptive C fibre evoked potentials can provide useful information about central changes related to hyperalgesia in rats. Recordings of tactile and CO(2)-laser C fibre evoked potentials (LCEPs) in forelimb and hind limb SI cortex were made 20-24h after UV-B irradiation of the heel at a dose that produced behavioural signs of hyperalgesia. ⋯ Tramadol, a centrally acting analgesic known to reduce hyperalgesia, induced changes that counteracted the changes produced by UV-B irradiation on transmission to SI cortex from the hind paw, but had no significant effect on time course of LCEPs from forelimb skin. Tactile evoked potentials were not affected by UV-B irradiation or tramadol. We conclude that altered sensory processing related to hyperalgesia is reflected in altered LCEPs in SI cortex.
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Randomized Controlled Trial Multicenter Study Comparative Study
A randomised controlled trial on the efficacy and side-effect profile (nausea/vomiting/sedation) of morphine-6-glucuronide versus morphine for post-operative pain relief after major abdominal surgery.
Morphine is the first choice of treatment of severe post-operative pain, despite the occurrence of often discomforting (post-operative nausea or vomiting (PONV)) and sometimes dangerous (sedation, respiratory depression) side effects. Literature data indicate that morphine's active metabolite, morphine-6-glucuronide (M6G), is a powerful analgesic with a possibly more favourable side-effect profile. In this multi-centre randomised controlled clinical trial patients undergoing major abdominal surgery were randomised to M6G or morphine treatment. ⋯ Sub-analysis showed a significant reduction in nausea levels in females on M6G (30% difference, P=0.034). In all patients, similar reductions of 30-35% were observed in anti-emetic use, vomiting, PONV (a combined measure of nausea and vomiting) in favour of M6G, persisting for the first 24h postoperatively. Reductions in sedation were observed in the first 4h post-operative period for M6G patients.
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Randomized Controlled Trial
Reference values of mechanical and thermal pain tests in a pain-free population.
Quantitative sensory tests are widely used in human research to evaluate the effect of analgesics and explore altered pain mechanisms, such as central sensitization. In order to apply these tests in clinical practice, knowledge of reference values is essential. The aim of this study was to determine the reference values of pain thresholds for mechanical and thermal stimuli, as well as withdrawal time for the cold pressor test in 300 pain-free subjects. ⋯ In conclusion, normative values of parameters related to pressure, heat and cold pain stimuli were determined. Reference values have to be stratified by body region, gender and age. The determination of these reference values will now allow the clinical application of the tests for detecting abnormal pain reactions in individual patients.
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A considerable number of Europeans suffer from chronic pain and are using opioids, particularly of the weak type. It is a clinical impression that many of these are driving or wish to drive a car. The aims of this study were to investigate if codeine influences driving ability in a simulator, and to examine if chronic pain per se might impair such functions. ⋯ The main finding in this simulator study was that codeine does not impair driving-related abilities over and above what is associated with chronic pain per se.
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Oxaliplatin is a key drug for colorectal cancer, but it causes acute peripheral neuropathy (triggered by cold) and chronic neuropathy (sensory and motor neuropathy) in patients. Neurotropin, a non-protein extract from the inflamed rabbit skin inoculated with vaccinia virus, has been used to treat various chronic pains. In the present study, we investigated the effect of neurotropin on the oxaliplatin-induced neuropathy in rats. ⋯ Neurotropin also inhibited the oxaliplatin-induced neurite degeneration in cultured pheochromocytoma 12 (PC12) and rat dorsal root ganglion (DRG) cells. On the other hand, neurotropin did not affect the oxaliplatin-induced cell injury in rat DRG cells. These results suggest that repeated administration of neurotropin relieves the oxaliplatin-induced mechanical allodynia by inhibiting the axonal degeneration and it is useful for the treatment of oxaliplatin-induced neuropathy clinically.