European journal of pain : EJP
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Randomized Controlled Trial Clinical Trial
Mechanically induced axon reflex and hyperalgesia in human UV-B burn are reduced by systemic lidocaine.
The mechanisms for the induction of primary mechanical hyperalgesia are unclear. We analyzed the neurogenic axon reflex erythema (flare) following phasic mechanical stimulation in normal and in UV-B irradiated skin. In a cross-over double blind design (n = 10), low dose of systemic lidocaine suppressed mechanical hyperalgesia in sunburned skin and in the mechanically induced flare. ⋯ Systemic lidocaine suppressed the mechanically induced flare as well as the mechanical hyperalgesia in sunburned skin, while leaving the impact-induced ratings in normal skin unchanged. Systemic lidocaine reduced these effects of sensitization, but did not reduce ratings in normal skin. As mechanically insensitive ("sleeping") nociceptors have been shown to mediate the axon-reflex in human skin, sensitization of this class of nociceptors might contribute also to the UV-B-induced primary mechanical hyperalgesia.
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Randomized Controlled Trial Clinical Trial
Impaired disengagement from threatening cues of impending pain in a crossmodal cueing paradigm.
This paper reports an experimental investigation of attentional engagement to and disengagement from cues of impending pain. Pain-free volunteers performed a cueing task in which they were instructed to detect somatosensory and tone targets. Target stimuli were preceded by visual cues informing participants of the modality of the impending stimuli. ⋯ Analyses revealed a similar amount of attentional engagement to both cues signalling somatosensory targets, irrespective of their threat value. However, participants had significantly more difficulty in disengaging attention from a threatening cue of impending pain compared to a cue signalling the non-painful vibrotactile target. Our findings provide further evidence that pain cues demand attention, particularly resulting in impaired disengagement.
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Randomized Controlled Trial Clinical Trial
Catastrophizing and internal pain control as mediators of outcome in the multidisciplinary treatment of chronic low back pain.
The aim of the present study was to examine (a) whether a cognitive-behavioral treatment (differentially) affects pain coping and cognition; and (b) whether changes in pain coping and cognition during treatment mediate treatment outcome. Participants in this randomized clinical trial were 148 patients with chronic low back pain attending a multidisciplinary treatment program consisting of operant-behavioral treatment plus cognitive coping skills training (N = 59) or group discussion (N = 58) or allocated to a waiting list control condition (N = 31). ⋯ Changes in catastrophizing and to a lesser degree in internal pain control mediated the reduction in level of depression and pain behavior following treatment. The use of behavioral and cognitive interventions aimed at decreasing catastrophizing thoughts about the consequences of pain and promoting internal expectations of pain control possibly constitute an important avenue of change irrespective of the type of treatment.
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Clinical Trial Controlled Clinical Trial
Peripheral effects of needle stimulation (acupuncture) on skin and muscle blood flow in fibromyalgia.
Acupuncture has become a widely used treatment modality in various musculoskeletal pain conditions. Acupuncture is also shown to enhance blood flow and recovery in surgical flaps. The mechanisms behind the effect on blood flow were suggested to rely on vasoactive substances, such as calcitonin gene-related peptide, released from nociceptors by the needle stimulation. ⋯ The results of the present study were partly similar to those earlier found at a corresponding site in healthy female subjects, i.e., deep muscle stimulation resulted in larger increase in skin blood flow (mean (SE)): 62.4% (13.0) and muscle blood flow: 93.1% (18.6), compared to baseline, than did subcutaneous insertion (mean (SE) skin blood flow increase: 26.4% (6.2); muscle blood flow increase: 46.1% (10.2)). However, in FM patients subcutaneous needle insertion was followed by a significant increase in both skin and muscle blood flow, in contrast to findings in healthy subjects where no significant blood flow increase was found following the subcutaneous needling. The different results of subcutaneous needling between the groups (skin blood flow: p=0.008; muscle blood flow: p=0.027) may be related to a greater sensitivity to pain and other somatosensory input in FM.
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The usefulness of the verbal pain rating scale (VRS) included in the Short Form 36 (SF-36) in identifying characteristics of long-term pain conditions, was analyzed using data from the 1994 Danish Health and Morbidity Survey. Based on the rating of pain intensity during a 4-week recall period the respondents were categorized into three groups: a high pain group (HPG) consisting of persons reporting moderate to severe pain (VRS 4-6), a low pain group (LPG) who rated their pain as very mild or mild (VRS 2-3), and a control group (CG) with no pain (VRS 1). The investigated sample comprised 3992 persons (HPG=563 persons, LPG=1714, and CG=1715 persons). ⋯ Mean numbers of in-hospital days were 1.60, 0.80, and 0.43 for the HPG, LPG, and CG, respectively. Our study suggest that one-dimensional pain intensity scoring using a simple VRS-scoring is useful as a screening instrument for identifying persons suffering from pain of a more complex nature. High intensity scores on a pain intensity scale should indicate to the investigator that she/he might be facing a person whose pain complaints and behavior are not only based on a pure biological background, but in whom also severe psychological and social problems might be present.