Articles: hyperalgesia.
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The mechanism of pain in chronic pancreatitis (CP) has yet to be explored. Proteinase-activated receptor 2 (PAR2) plays a pronociceptive role in visceral pain. The study aimed to assess the expression of PAR2 in dorsal root ganglia (DRGs) and validate its role of thermal hyperalgesia in CP. ⋯ The thermal hyperalgesia in CP is associated with an up-regulation of the PAR2 in DRGs. Proteinase-activated receptor 2 was involved in the pain generation in rats with CP.
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Randomized Controlled Trial
Local pain and spreading hyperalgesia induced by intramuscular injection of nerve growth factor are not reduced by local anesthesia of the muscle.
Injections with local anesthesia for therapeutic and diagnostic purposes are common clinical practice. This double-blind placebo controlled study explores the rational of local anesthetic blocks for the detection of muscle pain as the primary generator in spreading hyperalgesic conditions. ⋯ Muscle pain and spreading hyperalgesia induced by NGF is maintained despite anesthesia of the primary nociceptive locus. This indicates that intramuscular injection of local anesthetics may not be a valid diagnostic method for primary muscle pain.
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Nociceptor inputs can trigger a prolonged but reversible increase in the excitability and synaptic efficacy of neurons in central nociceptive pathways, the phenomenon of central sensitization. Central sensitization manifests as pain hypersensitivity, particularly dynamic tactile allodynia, secondary punctate or pressure hyperalgesia, aftersensations, and enhanced temporal summation. It can be readily and rapidly elicited in human volunteers by diverse experimental noxious conditioning stimuli to skin, muscles or viscera, and in addition to producing pain hypersensitivity, results in secondary changes in brain activity that can be detected by electrophysiological or imaging techniques. ⋯ Diagnostic criteria to establish the presence of central sensitization in patients will greatly assist the phenotyping of patients for choosing treatments that produce analgesia by normalizing hyperexcitable central neural activity. We have certainly come a long way since the first discovery of activity-dependent synaptic plasticity in the spinal cord and the revelation that it occurs and produces pain hypersensitivity in patients. Nevertheless, discovering the genetic and environmental contributors to and objective biomarkers of central sensitization will be highly beneficial, as will additional treatment options to prevent or reduce this prevalent and promiscuous form of pain plasticity.
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J Clin Neuromuscul Dis · Mar 2011
Review Case ReportsHyperalgesia after volar wrist tattoo: a case of complex regional pain syndrome?
Hyperalgesia after a volar wrist tattoo with features consistent with complex regional pain syndrome and a brief literature review is presented. This is the first case of disseminated hyperalgesia reported from a tattoo. ⋯ The response to prednisone was robust. Further cases may appear considering popularization of wrist tattoos by celebrities.
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Studies have demonstrated menstrual cycle influences on basal pain perception, but direct evidence of menstrual cycle influences on analgesic responses has not been reported in humans. Our aim was to determine whether the magnitude of morphine and pentazocine analgesia varied across the menstrual cycle. Sixty-five healthy women, 35 taking oral contraceptives (OC) and 30 normally cycling (NOC), underwent experimental pain assessment both before and after intravenous administration morphine (0.08mg/kg) or pentazocine (0.5mg/kg) compared to saline placebo. ⋯ Likewise, side effects for morphine were significantly higher in NOC women in the follicular phase than in the luteal phase (P=0.02). These findings suggest that sex hormones may influence opioid responses; however, the effects vary across medications and pain modalities and are likely to be modest in magnitude. Limited menstrual cycle effects on baseline pain responses were observed; however, morphine analgesia and side effects were greater during the follicular phase.