The journal of pain : official journal of the American Pain Society
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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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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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Approximately 70% of male rats receiving severe T8 spinal contusions develop allodynia in T5-7 dermatomes (at-level) beginning 2 weeks after injury. In contrast, rats having either complete transections or dorsal hemisections do not develop allodynia at-level after chronic spinal cord injury (SCI). In the present study, incomplete laceration and contusion injuries were made to test for neuroanatomical correlates between areas of white matter damage/sparing at the lesion epicenter and the presence/absence of allodynia. After incomplete laceration lesions and 6 weeks of behavioral testing, histological reconstruction and analysis of the lesion epicenters revealed a significant difference (P < .001) in the amount of ventrolateral funiculus (VLF) asymmetry between rats showing pain-like responses evoked by touch (74.5% +/- 8.4% side-to-side difference in VLF damage) versus those not responding to touch (11.3% +/- 4.4% side-to-side difference in VLF damage). A 5-week mean allodynia score for each rat that incorporates a full range of forces that are all innocuous in intact controls revealed that the degree of hypersensitivity at level is related to the extent of VLF asymmetry after SCI. No other damaged spinal white matter or gray matter area was correlated with sensitivity to touch. Similar findings were obtained for rats receiving T8 contusions, a more clinically relevant injury. These data suggest that different extents of damage/sparing between the 2 sides of VLF probably are a requisite for the development of allodynia after SCI. ⋯ A side-to-side lesion asymmetry after chronic SCI in a rodent model was found to be highly correlated with the presence and degree of allodynia. Greater insight of key factors contributing to the development and maintenance of chronic neuropathic pain is important for improving quality of life.