The journal of pain : official journal of the American Pain Society
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Comparative Study
Sex and pain-related psychological variables are associated with thermal pain sensitivity for patients with chronic low back pain.
Biologic and psychological associations with evoked pain sensitivity have been extensively studied in healthy subjects but not among subjects with clinical pain syndromes. This study involved patients with chronic low back pain and investigated whether: 1) sex differences existed for thermal pain sensitivity; and 2) sex, fear-avoidance beliefs, and/or pain catastrophizing influenced thermal pain sensitivity. Thirty-three consecutive patients enrolled in a pain rehabilitation program completed self-report questionnaires and underwent quantitative sensory testing with an established protocol for thermal stimuli. Women had elevated pain sensitivity for measures of tolerance and temporal summation but not for first pulse response. In the multivariate models predicting thermal pain sensitivity, sex was associated with tolerance, and fear-avoidance beliefs were associated with first pulse response. Sex and pain catastrophizing were associated with temporal summation of thermal pain. Future studies involving clinical samples are necessary to replicate these findings and to explore the involvement of cortical structures. ⋯ This study suggests that sex, fear-avoidance beliefs, and pain catastrophizing were associated with thermal pain sensitivity for patients with chronic low back pain. These results corroborated sex differences in tolerance and temporal summation observed in the experimental pain literature for healthy subjects. These results also suggest the potential for these specific pain-related beliefs to be associated with a sensitized state because previous studies have demonstrated their association to clinical pain reports, and this study demonstrated associations with thermal pain sensitivity.
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The purpose of this study was to identify and describe subgroup profiles based on self-reported pain intensity, disability, self-efficacy, fear of movement/(re)injury, and catastrophizing in patients with musculoskeletal pain. Two primary health care samples (n = 215 and n = 161) were used. Self-report questionnaires were completed at the start of physical therapy treatment. Cluster analysis was used to generate subgroups. Three subgroups were identified in sample 1 and replicated in sample 2. These were labeled "High self-efficacy-Low fear-avoidance," "Low self-efficacy-Low fear-avoidance," and "Low self-efficacy-High fear-avoidance." The subgroups differed significantly in work-status in both samples (P < .001), but not in age, gender, or duration of pain. The results show the presence of subgroups based on pain intensity, disability, self-efficacy, fear of movement/(re)injury, and catastrophizing. The profile patterns suggest that different management strategies may be relevant in each subgroup. ⋯ This article presents subgroups of patients with musculoskeletal pain with different profiles in pain intensity, disability, and psychosocial variables possible to modify by physical therapy management. The results could potentially aid clinicians in tailoring assessment and treatment approaches to each subgroup.
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The purpose of this investigation was to clarify mixed findings reported in selective attention investigations. To accomplish this, recently published dot-probe data from 36 patients with chronic musculoskeletal pain and 29 healthy control participants were reanalyzed with consideration of fear of pain (FOP) as a categorical variable. FOP groups were identified by using a variety of strategies and represented differing conceptualizations of the FOP construct. Selective attention for sensory pain, affect pain, and health catastrophe words was assessed by using raw dot-probe detection latencies and the bias, congruency, and incongruency indices. Analysis of the raw detection latencies revealed no significant interactions that permit inferences regarding attentional shifts to or away from specific word types. Analyses of the attention indices revealed no evidence of pain-related selective attention as a function of FOP or the interaction between clinical status and FOP, regardless of the FOP categorization method used; however, for FOP groups derived by using the cluster method, participants with high FOP--all patients--exhibited hypervigilance for all word types on the dot-probe task when compared with those with low FOP. Implications for various categorical conceptualizations of FOP and future research directions are discussed. ⋯ Fear of pain can be used to categorize people into groups more or less vulnerable to disabling effects of pain. When fear of pain groups are derived by using measures of general and pain-specific fearfulness, people with high fear of pain are likely to selectively attend all potentially threatening stimuli in their environment.
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The relief of neuropathic pain after spinal cord injury (SCI) remains daunting, because pharmacologic intervention works incompletely and is accompanied by multiple side effects. Transplantation of human cells that make specific biologic agents that can potentially modulate the sensory responses that are painful would be very useful to treat problems such as pain. To address this need for clinically useful human cells, the human neuronal NT2 cell line was used as a source to isolate a unique human neuronal cell line that synthesizes and secretes/releases the inhibitory neurotransmitters gamma-aminobutyric acid (GABA) and glycine. This new cell line, hNT2.17, expresses an exclusively neuronal phenotype, does not incorporate bromodeoxyuridine during differentiation, and does not express the tumor-related proteins fibroblast growth factor 4 and transforming growth factor-alpha during differentiation after 2 weeks of treatment with retinoic acid and mitotic inhibitors. The transplant of predifferentiated hNT2.17 cells was used in the excitotoxic SCI pain model, after intraspinal injection of the mixed AMPA/metabotropic receptor agonist quisqualic acid (QUIS). When hNT2.17 cells were transplanted into the lumbar subarachnoid space, tactile allodynia and thermal hyperalgesia induced by the injury were quickly and potently reversed. Control cell transplants of nonviable hNT2.17 cells had no effect on the hypersensitivity induced by QUIS. The effects of hNT2.17 cell grafts appeared 1 week after transplants and did not diminish during the 8-week course of the experiment when grafts were placed 2 weeks after SCI. Immunohistochemistry and quantification of the human grafts were used to ensure that many grafted cells were still present and synthesizing GABA at the end of the study. These data suggest that the human neuronal hNT2.17 cells can be used as a "biologic minipump" for antinociception in models of SCI and neuropathic pain. ⋯ This study describes the initial characterization and use of a human-derived cell line to treat neuropathic pain that would be suitable for clinical application, once further tested for safety and approved by the Food and Drug Administration. A dose of these human cells could be delivered with a spinal tap and affect the intrathecal spinal environment for sensory system modulation.
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Racial and ethnic disparities in healthcare persist in the U.S. Although pain is one of the most prevalent and disabling symptoms of disease, only a few studies have assessed disparities in pain in large racially and ethnically diverse, middle- to late aged community samples, thus limiting the generalizability of study findings in broader populations. With data from the 2000 Health and Retirement Study, we assessed the prevalence and impact of pain in a community sample of aging (> or =51 years old) non-Hispanic whites (n = 11,021), non-Hispanic blacks (n = 1,804), and Hispanics (n = 952) in the U.S. Pain, pain severity, activity limitation as a result of pain, comorbid conditions, and sociodemographic variables were assessed. Results showed that pain prevalence was 28%, and 17% of the sample reported activity limitation as a result of pain. Non-Hispanic blacks (odds ratio [OR], 1.78; 99% confidence interval [CI], 1.33-2.37) and Hispanics (OR, 1.80; 99% CI, 1.26-2.56) had higher risk for severe pain compared with non-Hispanic whites. Analyses of respondents with pain (n = 3,811) showed that having chronic diseases (2 comorbid conditions, OR, 1.5; 99% CI, 1.09-2.17), psychological distress (OR, 1.99; 99% CI, 1.54-2.43), being a Medicaid recipient (OR, 1.63; 99% CI, 1.17-2.25), and lower educational level (OR, 1.45; 99% CI, 1.14-1.85) were significant predictors for severe pain and helped to explain racial/ethnic differences in pain severity. ⋯ This study, which used a large racially and ethnically diverse community sample, provided empirical evidence that racial/ethnic difference in pain severity in aging community adults in the U.S. can be accounted for by differential vulnerability in terms of chronic disease, socioeconomic conditions, and access to care.