European journal of pain : EJP
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Phantom phenomena are frequent following amputation, but how this often painful experience is modified or triggered by spontaneous events or sensations often puzzles amputees and clinicians alike. We explored triggers of phantom phenomena in a heterogeneous sample of 264 upper and lower limb adult amputees with phantom sensations. Participants completed a structured questionnaire to determine the prevalence and nature of the triggers of phantom phenomena. ⋯ Finally, habitual "forgetting" behaviors were most common soon after amputation, whereas other more adaptive schemata (e.g., self-defense) were equally likely to be performed at any time following amputation. Various likely inter-related mechanisms are discussed in relation to phantom triggers. Ultimately, optimizing stump and neuroma management, as well as restoring function of central networks for pain, limb movement, and amputation-related memories, should help manage spontaneously triggered phantom phenomena.
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This study examined differences between Asians and non-Hispanic Whites (Whites) in pain sensitivity, and its relationship to mean arterial pressure (MAP) and heart rate (HR). In 30 Whites (50% female) and 30 Asians (50% female), experimental pain sensitivity was assessed with a hand cold pressor task, yielding measures of pain threshold, tolerance, intensity, and unpleasantness. Mean arterial pressure and HR measurements taken at rest and in response to speech stress were assessed. ⋯ These results indicate that Asian Americans are more sensitive to experimental pain than Whites and suggest ethnic differences in endogenous pain regulatory mechanisms (e.g. MAP and HR). The results may also have implications for understanding ethnic differences in clinical pain.
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Despite using prescribed pain medications, patients with neuropathic pain continue to experience moderate to severe pain. There is a growing recognition of a potent peripheral opioid analgesia in models of inflammatory and neuropathic pain. The goal of this study was to characterize the temporal and spatial expression of mu opioid receptor (mOR) mRNA and protein in primary afferent neurons in a rat L5 spinal nerve ligation model of persistent neuropathic pain. ⋯ Western blot analysis revealed a persistent increase in mOR protein expression, although immunohistochemistry showed no change in number of mOR-positive neurons in the uninjured L4 DRG. Interestingly, mOR protein expression was reduced in the skin on days 14 and 35 post-nerve injury and in the L4 and L5 spinal cord on day 35 post-nerve injury. These temporal and anatomically specific changes in mOR expression following nerve injury are likely to have functional consequences on pain-associated behaviors and opioid analgesia.
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Multicenter Study
Multi-centre European study of breakthrough cancer pain: pain characteristics and patient perceptions of current and potential management strategies.
This study involved 320 cancer patients from four Northern European countries. Patients with breakthrough pain were questioned about the characteristics of their pain, the current management of their pain, and the acceptability/utility of alternative routes of administration. The median number of episodes was 3/day. ⋯ Forty-two percent patients would definitely consider using an intranasal product, with 26% patients stating they would definitely not use such a preparation; patients from Denmark and Sweden were less likely to answer positively, and a positive response was associated with male gender, and previous use of the route. Forty-four percent patients reported regular nasal problems. Sixty percent patients would definitely consider using a subcutaneous product, and 44% patients would definitely consider using an intrapulmonary product.
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We have studied scalding-type burn injury-induced activation of extracellular signal-regulated kinase 1/2 (ERK1/2) in the spinal dorsal horn, which is a recognised marker for spinal nociceptive processing. At 5min after severe scalding injury to mouse hind-paw, a substantial number of phosphorylated ERK1/2 (pERK1/2) immunopositive neurons were found in the ipsilateral dorsal horn. At 1h post-injury, the number of pERK1/2-labelled neurons remained substantially the same. ⋯ By 6h post-injury, the number of labelled neurons was reduced on both sides without there being significant difference between the two sides. A similar pattern of severe scalding injury-induced activation of ERK1/2 in spinal dorsal horn neurons over the same time-course was found in mice which lacked the transient receptor potential type 1 receptor (TRPV1) except that the extent to which ERK1/2 was activated in the ipsilateral dorsal horn at 5 min post-injury was significantly greater in wild-type animals when compared to TRPV1 null animals. This difference in activation of ERK1/2 in spinal dorsal horn neurons was abolished within 1h after injury, demonstrating that TRPV1 is not essential for the maintenance of ongoing spinal nociceptive processing in inflammatory pain conditions in mouse resulting from at least certain types of severe burn injury.