The journal of pain : official journal of the American Pain Society
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Individuals with chronic craniofacial pain experience symptoms that are consistent with central sensitization. In fact, central sensitization may constitute the major disease process in these conditions, particularly if the original injury has healed or the condition is idiopathic. To understand central sensitization we have developed a conjugate of substance P and cholera toxin (SP-CTA). SP-CTA is selectively taken up by cells that express neurokinin receptors. Twenty-four hours following intracisternal administration of SP-CTA, wild-type rats and mice demonstrated signs of persistent background nociception, but when tested for facial cold sensitivity, they did not differ from controls. However, treating the SP-CTA-injected animals with naloxone exposed cold hypersensitivity in the face. Mu-opioid receptor knockout mice treated with SP-CTA demonstrated hypersensitivity without naloxone treatment. These findings suggest that central sensitization leads to activation of an endogenous opioid system. The data also demonstrate that the intracisternal administration of SP-CTA in rodents is a useful model for studying central sensitization as a disease process without having to induce a peripheral injury. ⋯ Central sensitization is a concern in many craniofacial pain conditions. In this project, we utilize a conjugate of substance P and the catalytic subunit of cholera toxin to induce central sensitization in the nucleus caudalis of rodents. The data indicate that the injected animals become hypersensitive in the face.
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Randomized Controlled Trial
The association of single nucleotide polymorphisms in the catechol-O-methyltransferase gene and pain scores in female patients with major depressive disorder.
We tested the hypothesis that single nucleotide polymorphisms (SNPs) in the catechol-O-methyltransferase (COMT) gene are associated with baseline pain levels in patients with major depressive disorder (MDD). Pain levels were quantified using a visual analog scale (VAS) for pain. Data from 159 female and 93 male self-reported white patients with MDD were analyzed. The associations between a haplotype previously associated with pain sensitivity created using COMT SNPs rs6269, rs4633, rs4818, and rs4680, and the proportion of female patients with "Pain While Awake" and "Overall Pain" at baseline were statistically significant (P < .05). In male patients, no statistically significant associations between COMT haplotypes and baseline pain scores were seen. The rs165599 SNP, which has previously been associated with response of depressive symptoms to treatment in patients with MDD, did not impact baseline pain in either gender. In conclusion, baseline pain levels appear to be associated with the COMT pain sensitivity haplotype in female patients with MDD. ⋯ This article presents associations of the COMT pain sensitivity haplotype and baseline pain levels in female patients with MDD. This finding could potentially help clinicians who seek to assess how genetic polymorphisms may contribute to a patient's pain experience.
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Considerable evidence has linked catastrophizing to pain responses, and recent experimental pain research has suggested that situational catastrophizing, measured during or immediately after laboratory pain procedures, is strongly related to pain ratings of standardized noxious stimuli. However, given that most experimental pain protocols involve "static" assessments of pain ratings and catastrophizing at a single time point, the direction by which these factors may affect each other remains unclear. Does catastrophizing influences one's subsequent pain responses or do individual differences in the perceived severity of pain lead to differential rates of catastrophizing? Little is known regarding the course of these variables. Using a cross-lagged panel analysis, we evaluated whether changes in situation-specific catastrophizing preceded changes in laboratory-induced pain responses, or vice versa, during tonic capsaicin pain stimulation. Topical application of a 10% capsaicin cream was applied to the dorsal aspect of the nondominant hand of 38 healthy participants. Situation-specific catastrophizing and pain ratings were obtained at Early (0 to 15 minutes), Mid (15 to 30 minutes), and Final (30 to 35 minutes) periods during capsaicin pain. Analyses revealed that Early-to-Mid changes in catastrophizing ratings prospectively accounted for unique variance in subsequent Mid-to-Final changes in pain ratings, whereas Early-to-Mid changes in pain ratings did not account for unique variance in Mid-to-Final changes in catastrophizing ratings. That is, participants who showed the largest initial increases in catastrophizing reported the greatest subsequent increases in pain. Controlling for the reported change in stress did not affect this pattern of results. These findings provide empirical evidence that a situation-specific catastrophizing process might precede and contribute to subsequent increases in pain experience. Limitations of the present study and possible future research directions are discussed. ⋯ The present study adds to a growing literature on prospective associations between catastrophizing and pain. These results provide initial evidence, in healthy individuals, that changes in catastrophizing may precede changes in pain response.
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Juvenile primary fibromyalgia syndrome (JPFS) is a chronic pain condition associated with significant impairment in physical functioning, but no studies have used newer technologies such as actigraphy to document objective physical activity levels in JPFS. This is the first study to objectively describe physical activity in JPFS patients and examine the relationship of pain, perceived functional impairment, and depressive symptoms on physical activity. One hundred four clinically referred adolescents with JPFS (ages 11 to 18 years) wore a hip-mounted actigraph for 1 week. Data on pain intensity, functional disability, depressive symptoms, and psychiatric diagnoses were obtained using self- and parent-report measures and a standardized psychiatric interview. Results showed that younger patients were more active. Pain intensity was not significantly associated with physical activity levels overall, but the most highly active group of adolescents reported lower levels of pain and disability than the least active. Parent report of adolescents' physical functioning and depressive symptoms were significantly correlated with adolescents' physical activity levels. Actigraphy provides a unique source of information about physical functioning which is distinct from adolescents' self-report of physical functioning in JPFS. Preliminary findings suggest that further study of factors that predict perceived and actual physical functioning in JPFS is warranted. ⋯ This study presents the results of physical activity monitoring in adolescents with JPFS using actigraphy. Results indicate that actigraphy provides a unique source of objective information that can advance our understanding of physical disability in JPFS and the factors associated with physical impairment.
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The aim of this mixed methods exploratory study was to describe pediatric nurses' cognitive representations (CRs) of the assessment and management of children's pain and to determine the relationships between their CRs and their choices about pain assessment and morphine administration. We recruited a convenience sample of 87 nurses caring for hospitalized children at 4 institutions. We measured the CRs with the Conceptual Content Cognitive Map (3CM) technique and pain assessment and morphine administration with smiling and grimacing child vignettes. We used content analyses for the 3CM data and fit logistic regression models to predict participants' analgesic choice for each vignette. Nearly all (91%) participants identified the child's behavior as an assessment approach; 48% indicated it as most important. Participants (92%) identified pharmacologic as a management approach; 47% indicated it as most important. Participants' CRs did not predict assessment or morphine administration choices. Significantly more participants chose the appropriate analgesic response for the grimacing child than they did for the smiling child. Nurses with more years of pediatric experience were less likely to select administration of the appropriate morphine dose. The 3CM method provided insights into nurses' thinking about pain that are indicative of gaps, which may be amenable to interventions. ⋯ Findings are from an innovative, unique measure of nurses' knowledge and beliefs about the complex phenomenon of children's pain management. Extensive details about the thought processes of pediatric nurses regarding pain assessment and management surfaced through this analysis, which provide excellent information for direction of future research and practice innovations.