Pain
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparative study of electronic vs. paper VAS ratings: a randomized, crossover trial using healthy volunteers.
The visual analogue scale (VAS) is an established, validated, self-report measure usually consisting of a 10 cm line on paper with verbal anchors labeling the ends. Palmtop computers (PTCs also known as personal digital appliances) have incorporated VAS entry by use of a touch screen. However, the validity and psychophysical properties of the electronic VAS have never been formally compared with the conventional paper VAS. ⋯ The median of correlations comparing eVAS and pVAS ratings was 0.99 for verbal stimuli and 0.98 for sensory stimuli. Multivariate analyses showed equivalent stimuli to be rated much the same whether entered on paper VAS or PTC touch screen VAS (P < 0.0001). Support was found for the validity of the computer version of the VAS scale.
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Randomized Controlled Trial Clinical Trial
Sensory stimulation (TENS): effects of parameter manipulation on mechanical pain thresholds in healthy human subjects.
Transcutaneous electrical nerve stimulation (TENS) is a popular form of electrostimulation. Despite an extensive research base, there remains no consensus regarding the parameter selection required to achieve maximal hypoalgesic effects. The aim of this double blind, sham-controlled study was to investigate the relative hypoalgesic effects of different TENS parameters (frequency, intensity and stimulation site) upon experimentally induced mechanical pain. ⋯ Whilst high frequency, 'strong but comfortable' intensity, segmental stimulation produced comparable hypoalgesic levels during stimulation, this effect was not sustained post-stimulation. Stimulation at a combination of the two sites did not produce any greater hypoalgesic effects. These results may have implications for the clinical use of sensory stimulation.
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Drugs that inhibit reuptake of monoamines are frequently used to treat pain syndromes, e.g. neuropathy or fibromyalgia, where mechanical allodynia is present. Several lines of evidence suggest the involvement of supraspinal sites of action of these drugs. However, a direct study of supraspinal serotonin (5-HT) or norepinephrine (NE) release in an animal model in which allodynia is expressed, e.g. neuropathy, has not been done. ⋯ This study is the first to demonstrate changes in monoamine release supraspinally in NP rats. The differential effect between VB thalamus and hypothalamus suggests that a terminal field change may be involved. Putative mechanisms for mediating this change include alterations of GABA-ergic systems and/or plasticity related to alterations in N-methyl-D-aspartate receptor activation and nitric oxide release related to afferent hyperactivity induced by neuropathic pain.
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A systematic review and subset meta-analysis of published randomised controlled trials of psychological therapies for children and adolescents with chronic pain is reported. A search of four computerised abstracting services recovered 123 papers from which 28 potential trials were identified. Eighteen met the criteria for inclusion in the review. ⋯ Meta-analysis was applicable for 12 headache trials and one trial of recurrent abdominal pain using the Pain Index. The odds-ratio for a 50% reduction in pain was 9.62 and the number needed to treat was 2.32, indicating that the psychological treatments examined are effective in reducing the pain of headache. The quality of the 18 trials retrieved is narratively reviewed and suggestions for the development of trials in this field are made.
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Comparative Study
Inward currents in primary nociceptive neurons of the rat and pain sensations in humans elicited by infrared diode laser pulses.
Radiant heat is often used to study nociception in vivo. We now used infrared radiation generated by a diode laser stimulator (wavelength 980 nm) to investigate transduction mechanisms for noxious heat stimuli in acutely dissociated dorsal root ganglion (DRG) neurons of rats in vitro. The laser stimulator offered the unique opportunity to test whether the same stimuli also elicit pain sensations in humans. ⋯ No significant differences were seen between the pain thresholds in hairy and in glabrous skin, probably due to the deep penetration of this laser radiation. The mean pain threshold for stimuli > or =200 ms in humans was 2.5 +/- 0.2 J mm(-2) (n = 11), and did not differ from the thresholds for the induction of I(heat) in vitro. Our results indicate that I(heat) in primary sensory neurons can be activated by infrared laser pulses that are painful in humans.