The journal of pain : official journal of the American Pain Society
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Randomized Controlled Trial
Repetitive transcranial magnetic stimulation is efficacious as an add-on to pharmacological therapy in complex regional pain syndrome (CRPS) type I.
Single-session repetitive transcranial magnetic stimulation (rTMS) of the motor cortex (M1) is effective in the treatment of chronic pain patients, but the analgesic effect of repeated sessions is still unknown. We evaluated the effects of rTMS in patients with refractory pain due to complex regional pain syndrome (CRPS) type I. Twenty-three patients presenting CRPS type I of 1 upper limb were treated with the best medical treatment (analgesics and adjuvant medications, physical therapy) plus 10 daily sessions of either real (r-) or sham (s-) 10 Hz rTMS to the motor cortex (M1). Patients were assessed daily and after 1 week and 3 months after the last session using the Visual Analogical Scale (VAS), the McGill Pain Questionnaire (MPQ), the Health Survey-36 (SF-36), and the Hamilton Depression (HDRS). During treatment there was a significant reduction in the VAS scores favoring the r-rTMS group, mean reduction of 4.65 cm (50.9%) against 2.18 cm (24.7%) in the s-rTMS group. The highest reduction occurred at the tenth session and correlated to improvement in the affective and emotional subscores of the MPQ and SF-36. Real rTMS to the M1 produced analgesic effects and positive changes in affective aspects of pain in CRPS patients during the period of stimulation. ⋯ This study shows an efficacy of repetitive sessions of high-frequency rTMS as an add-on therapy to refractory CRPS type I patients. It had a positive effect in different aspects of pain (sensory-discriminative and emotional-affective). It opens the perspective for the clinical use of this technique.
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Comparative Study
Comparisons of catastrophizing, pain attitudes, and cold-pressor pain experience between Chinese and European Canadian young adults.
Experimental pain research indicates ethnic differences in pain experience. Most of the cross-cultural pain research studied African Americans and Hispanics with little data available for Asian groups. This study examined differences in pain catastrophizing, pain attitudes, and pain responses between Chinese and European Canadian young adults. Prior to completing a cold-pressor (CP) task, 80 Chinese and 80 European Canadian undergraduate students were administered measures of pain catastrophizing and pain attitudes, including stoicism and cautiousness. Pain threshold, pain tolerance, and pain intensity were measured during the CP task. The Short Form-McGill Pain Questionnaire was administered immediately postimmersion to measure sensory and affective pain. While there was no group difference in pain threshold and pain intensity, Chinese participants displayed lower pain tolerance and reported higher SF-MPQ-Affective than European Canadians. Regarding psychological variables, there was no difference in stoicism and cautiousness between groups, but Chinese participants reported greater pain catastrophizing. Mediational analysis indicated that pain catastrophizing mediated the group differences in SF-MPQ-Affective score. The implications of the findings and future research were discussed. ⋯ The study found ethnic differences in cold-pressor responses, in which Chinese undergraduates reported higher levels of pain compared to their Euro-Canadian counterparts. The finding that pain catastrophizing mediated the ethnic difference in SF-MPQ-Affective scores indicated the importance of examining the role of catastrophizing in pain reports from Chinese and Euro-Canadian patients.
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An aim of the National Institutes of Health (NIH) Patient Reported Outcomes Measurement Information System (PROMIS) initiative is to develop item banks and computerized adaptive tests (CAT) that are applicable across a wide variety of chronic disorders. The PROMIS Pediatric Cooperative Group has concentrated on the development of pediatric self-report item banks for ages 8 through 17 years. The objective of the present study is to describe the Item Response Theory (IRT) analysis of the NIH PROMIS pediatric pain item bank and the measurement properties of the new unidimensional PROMIS Pediatric Pain Interference Scale. Test forms containing pediatric pain items were completed by a total of 3048 respondents. IRT analyses regarding scale dimensionality, item local dependence, and differential item functioning were conducted. A pain item pool was developed to yield scores on a T-score scale with a mean of 50 and standard deviation of 10. The recommended 8-item unidimensional short form for the PROMIS Pediatric Pain Interference Scale contains the item set which provides the maximum test information at the mean (50) on the T-score metric. A simulated CAT was computed that provides the most information at 5 possible score locations (30, 40, 50, 60, and 70 on the T-score metric). ⋯ The present study provides initial calibrations of the NIH PROMIS pediatric pain item bank and the creation of the PROMIS Pediatric Pain Interference Scale. It is anticipated that this new scale will have application in pediatric chronic and recurrent pain.
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Attentional biases towards pain-related words of chronic and acute low back pain (LBP) patients were compared with healthy pain-free controls. Specifically, the aims were to determine: 1) whether chronic LBP patients demonstrate attentional biases compared to pain-free controls; 2) whether observed biases are also present in those with acute LBP; and 3) whether observed biases are associated with pain-related fear among the pain groups. Four groups were recruited: 1) acute LBP patients; 2) chronic LBP patients from physiotherapy practices; 3) chronic LBP patients from a tertiary referral pain-management center; and 4) healthy pain-free controls. Participants were assessed on the dot-probe computer task for attentional bias to pain-related words. All 3 pain groups demonstrated biases compared to controls on sensory but not on affective, disability, or threat words. Among the pain groups, those with low and moderate levels of fear of (re)injury demonstrated biases towards sensory pain words that were absent in those with high levels of fear, which is counterintuitive to what the fear of (re)injury model suggests. These results suggest that the experience of pain, rather than duration, is the primary indicator of the presence of pain-related biases. ⋯ Attentional biases are present in chronic and acute pain. Biases towards sensory-pain stimuli were demonstrated regardless of pain duration; however, they were present in those with low and moderate levels of fear of (re)injury only and not those high in fear. These findings are not consistent with the fear of (re)injury model.
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Based on prior research identifying dispositional optimism as a predictor of placebo responding, the present study tested the hypothesis that individuals high in optimism would be more likely to respond to a placebo analgesic. Optimists and pessimists were randomly assigned to a placebo expectation condition or a no expectation condition before a cold pressor task. Blood pressure and heart rate were recorded before and during the cold pressor task, and participant ratings of pain and expectations were obtained immediately after the task. Analysis of the expectation manipulation revealed that the placebo instruction was successful in altering participant expectancy during the cold pressor. Supporting the main hypothesis, dispositional optimism was associated with lower pain ratings in the placebo condition but not in the control condition. Because dispositional optimism can alter placebo responding to laboratory pain, future studies should examine the potential role that this individual difference factor may play in patient responsivity to pharmacological and nonpharmacological treatments for clinical pain. ⋯ This study examined the possibility that individual differences can predict placebo analgesia. Participants were randomly assigned to receive either a placebo expectation or no expectation before a cold pressor task. Dispositional optimism was related to less cold pressor pain in the placebo condition as compared with the control condition.