European journal of pain : EJP
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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
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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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.
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Although cannabinoids have anti-hyperalgesic effects in animal models of nerve injury, there are currently very few prospective trials of the efficacy of cannabinoids in neuropathic pain in humans. This open label prospective study investigated the safety, tolerability and analgesic benefit of oral Delta-9-tetrahydrocannabinol (THC) titrated to a maximal dosage of 25 mg/day in 8 consecutive patients with chronic refractory neuropathic pain. Spontaneous ongoing and paroxysmal pain, allodynia and paresthesias were assessed. ⋯ Seven patients suffered from side effects necessitating premature arrest of the drug in 5 of them. THC (mean dosage: 16.6+/-6.5 mg/day) did not induce any significant effects on ongoing and paroxysmal pain, allodynia, quality of life, anxiety/depression scores and functional impact of pain. These results do not support an overall benefit of THC in pain and quality of life in patients with refractory neuropathic pain.
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Clinical Trial
Children's ratings of the intensity and unpleasantness of post-operative pain using facial expression scales.
This study explored whether global unidimensional self-report pain scales based on facial expression help children separately estimate the sensory and affective magnitude of post-operative pain. Ninety paediatric elective surgery patients (in two age groups: 5-9 and 10-15 years) used each of four scales to estimate pain intensity and pain affect during the first 2 days after surgery. The four scales were: Faces Pain Scale (FPS), Facial Affective Scale (FAS), and the Coloured Analogue Scale (CAS) (one for intensity and one for unpleasantness). ⋯ No systematic age effects were observed. It was concluded that the FPS and the FAS may partly measure different aspects of the postoperative pain experience in children, although shared instrument variance may obscure true estimates of covariation in ratings of intensity and affective magnitude. The clinical relevance of the present results remains to be determined.