Pain
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Randomized Controlled Trial Comparative Study Clinical Trial
Postsurgical pain outcome assessment.
Reliable and valid measures of pain are essential for conducting clinical trials of pain treatments. Perhaps the most important aspect of a pain measure's validity is its sensitivity, or ability to detect changes in pain over time and due to treatment. Several factors may affect a measure's sensitivity, including the complexity of the rating task for the measure, the number of pain intensity levels assessed by the measure, the dimension of pain assessed (e.g. pain intensity vs. pain relief), and the number of individual ratings (e.g. single rating vs. composite score) used to create the measure. ⋯ However, contrary to our prediction, a composite measure of outcome made up of all three measures was not consistently superior to the individual measures for detecting treatment effects. Finally, we found that pain relief ratings were related to, but also distinct from, change in pain intensity as measured by changes in pain intensity ratings from baseline to each postmedication assessment point. These findings have important implications for the assessment of pain in clinical trials.
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The non-communicating children's pain checklist (NCCPC) has displayed preliminary validity and reliability for measuring pain in children with severe cognitive impairments (Dev Med Child Neurol 42 (2000) 609). This study provides evidence of the psychometric properties of a revised NCCPC (NCCPC-R) with a larger cohort of children. Caregivers of 71 children with severe cognitive impairments (aged 3-18) conducted observations of their children using the NCCPC-R during a time of pain and a time without pain. ⋯ Analyses of children's individual scores indicated up to 95% of their scores were consistent. Receiver operating characteristic curves suggest a score of 7 or greater on the NCCPC-R as indicative of pain in children with cognitive impairments, with 84% sensitivity and up to 77% specificity. These results provide evidence of NCCPC-R having excellent psychometric properties.
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We developed a mouse model of neuropathic cancer pain by inoculating Meth A sarcoma cells to the immediate proximity of the sciatic nerve in BALB/c mice. The tumor grows predictably with time and gradually compresses the nerve, thereby causing nerve injury. Time courses of thermal hyperalgesia and mechanical sensitivity to von Frey hairs were determined and signs of spontaneous pain were evaluated. ⋯ In the CCI mice, severe damage to myelinated fibers, especially large fibers, was observed and unmyelinated fibers were damaged to a lesser degree. These results suggest that gradual compression of a nerve by a malignant tumor results in nerve damage with a profile considerably different from that of chronic constriction injury produced by loose ligation of the nerve. Our new tumor model may be useful in studies of neuropathic cancer pain due to nerve compression by malignant tumors.
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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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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.