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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Quantitative sensory testing (QST) is an instrument to assess positive and negative sensory signs, helping to identify mechanisms underlying pathologic pain conditions. In this study, we evaluated the test-retest reliability (TR-R) and the interobserver reliability (IO-R) of QST in patients with sensory disturbances of different etiologies. In 4 centres, 60 patients (37 male and 23 female, 56.4±1.9years) with lesions or diseases of the somatosensory system were included. ⋯ We conclude that standardized QST performed by trained examiners is a valuable diagnostic instrument with good test-retest and interobserver reliability within 2days. With standardized training, observer bias is much lower than random variance. Quantitative sensory testing performed by trained examiners is a valuable diagnostic instrument with good interobserver and test-retest reliability for use in patients with sensory disturbances of different etiologies to help identify mechanisms of neuropathic and non-neuropathic pain.
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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.
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Review Meta Analysis
Acceptance-based interventions for the treatment of chronic pain: a systematic review and meta-analysis.
Acceptance-based interventions such as mindfulness-based stress reduction program and acceptance and commitment therapy are alternative therapies for cognitive behavioral therapy for treating chronic pain patients. To assess the effects of acceptance-based interventions on patients with chronic pain, we conducted a systematic review and meta-analysis of controlled and noncontrolled studies reporting effects on mental and physical health of pain patients. All studies were rated for quality. ⋯ It is recommended to focus on therapies that integrate mindfulness and behavioral therapy. Acceptance-based therapies have small to medium effects on physical and mental health in chronic pain patients. These effects are comparable to those of cognitive behavioral therapy.
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Randomized Controlled Trial Comparative Study Clinical Trial
A randomised, five-parallel-group, placebo-controlled trial comparing the efficacy and tolerability of analgesic combinations including a novel single-tablet combination of ibuprofen/paracetamol for postoperative dental pain.
Combination analgesia is often recommended for the relief of severe pain. This was a double-blind, 5-arm, parallel-group, placebo-controlled, randomised, single-dose study designed to compare the efficacy and tolerability of a novel single-tablet combination of ibuprofen and paracetamol with that of an ibuprofen/codeine combination, and a paracetamol/codeine combination, using the dental impaction pain model. Subjects with at least 3 impacted third molars and experiencing moderate to severe postoperative pain were randomised to receive: 1 or 2 tablets of a single-tablet combination of ibuprofen 200mg/paracetamol 500mg; 2 tablets of ibuprofen 200 mg/codeine 12.8mg; 2 tablets of paracetamol 500mg/codeine 15mg; or placebo. ⋯ Adverse events were uncommon during this study and treatment emergent adverse events were statistically significantly less frequent in the groups taking the ibuprofen/paracetamol combination compared with codeine combinations. In conclusion, 1 or 2 tablets of a single-tablet combination of ibuprofen 200mg/paracetamol 500mg provided highly effective analgesia that was comparable with, or superior to, other combination analgesics currently indicated for strong pain. A single-tablet combination of ibuprofen 200mg/paracetamol 500mg provides highly effective analgesia, comparable or superior to other combination analgesics indicated for strong pain.