Articles: hyperalgesia.
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Review Meta Analysis
Do opioids induce hyperalgesia in humans? An evidence-based structured review.
DESIGN/OBJECTIVES: Consistent rodent evidence indicates that opioid exposure will decrease the rodent's pain threshold (ptr). This is termed opioids-induced hyperalgesia (OIH). Currently, the consistency of the evidence for the occurrence of OIH in humans is unclear. This is a structured evidence-based review for all levels of evidence (all studies and case reports) on OIH in humans in order to determine the consistency of this evidence. ⋯ There is not sufficient evidence to support or refute the existence of OIH in humans except in the case of normal volunteers receiving opioid infusions. Prospective CPP clinical studies measuring ptrs and tolerances pre- and post-opioid placement with CPP non-opioid control groups are required.
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Randomized Controlled Trial
The effect of local anaesthetic on age-related capsaicin-induced mechanical hyperalgesia--a randomised, controlled study.
Adults over 65 years exhibit a prolonged punctate hyperalgesia induced by topical application of capsaicin. The aim of this study was to investigate the role of peripheral afferent input in the slowed resolution of punctate hyperalgesia in older people. Twenty young (25.7+/-4.8 years) and 19 old (74.9+/-4.4 years) healthy adults were recruited, and subjects in each age group were randomly assigned to receive either EMLA cream (a local anaesthetic) (n=10 in each age group) or Sorbolene treatment (n=9 in the older group, n=10 in the young group) after the development of punctate hyperalgesia. ⋯ Stoicism and cautiousness measured with Pain Attitude Questionnaire were negatively correlated with highest pain rating in the young, but not in the older groups. We suggest that the prolonged punctate hyperalgesia in older adults is possibly sustained by central mechanisms, indicating age differences in central plasticity following acute injury. The relationship between such age-related changes and the chronicity of pain in older adults should be further explored.
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In animal studies, thermal sensitivity is mostly evaluated on the basis of nociceptive reaction latencies in response to a given thermal aversive stimulus. However, these techniques may be inappropriate to differentiate allodynia from hyperalgesia or to provide information differentiating the activation of nociceptor subtypes. The recent development of dynamic hot and cold plates, allowing computer-controlled ramps of temperature, may be useful for such measures. In this study, we characterized their interest for studying thermal nociception in freely moving mice and rats. We showed that escape behavior (jumps) was the most appropriate parameter in C57Bl/6J mice, whereas nociceptive response was estimated by using the sum of paw lickings and withdrawals in Sprague-Dawley rats. We then demonstrated that this procedure allows the detection of both thermal allodynia and hyperalgesia after peripheral pain sensitization with capsaicin in mice and in rats. In a condition of carrageenan-induced paw inflammation, we observed the previously described thermal hyperalgesia, but we also revealed that rats exhibit a clear thermal allodynia to a cold or a hot stimulus. These results demonstrate the interest of the dynamic hot and cold plate to study thermal nociception, and more particularly to study both thermal allodynia and hyperalgesia within a single paradigm in awake and freely moving rodents. ⋯ Despite its clinical relevance, thermal allodynia is rarely studied by researchers working on animal models. As shown after stimulation of capsaicin-sensitive fibers or during inflammatory pain, the dynamic hot and cold plate validated in the present study provides a useful tool to distinguish between thermal allodynia and thermal hyperalgesia in rodents.
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Nuclear factor-kappa B (NF-kappaB) is a gene transcriptional regulator of inflammatory cytokines. We investigated the transduction efficiency of NF-kappaB decoy to dorsal root ganglion (DRG), as well as the decrease in nerve injury, mechanical allodynia, and thermal hyperalgesia in a rat lumbar disc herniation model. Forty rats were used in this study. ⋯ Mechanical allodynia and thermal hyperalgesia were significantly suppressed in the herniation + decoy group. NF-kappaB decoy was transduced into DRGs in vivo. NF-kappaB decoy may be useful as a target for clarifying the mechanism of sciatica caused by lumbar disc herniation.
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Clinical Trial
Influence of repeated painful procedures and sucrose analgesia on the development of hyperalgesia in newborn infants.
This study determined the effects of cumulative exposure to painful needle procedures and sucrose analgesia on the development of remote hyperalgesia in newborn infants, defined as an increase in response to a normally painful stimulus at a site distal from the site of injury. One-hundred and twenty healthy newborns and 120 healthy newborn infants of diabetic mothers equally randomized to sucrose analgesia or placebo prior to all needle procedures in the first two days after birth were divided into two exposure groups according to number of needle procedures they had undergone [high (> or =5) or low (< or =4)] using the median cut-off technique. Compared to the low exposure group, infants in the high exposure group had a higher pain response during a subsequent venipuncture distal to the site of previous injury, assessed by the Premature Infant Pain Profile (PIPP) [7.1 vs. 8.4; p=0.012] and Visual Analog Scale (VAS) [2.5 cm vs. 3.2 cm; p=0.047], and a trend for longer cry duration [25.7 s vs. 33.8 s; p=0.171]. ⋯ Sucrose reduced PIPP, VAS, and cry duration scores during venipuncture, but did not prevent hyperalgesia (p>0.05). There was a preponderance of infants of diabetic mothers in the high exposure group; however, the analysis did not demonstrate this to be a confounding factor. In conclusion, sucrose analgesia for repeated painful procedures in the first day of life does not prevent development of remote hyperalgesia in newborns.