The journal of pain : official journal of the American Pain Society
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An important construct in understanding pain-related disability is pain-related fear. Heightened pain-related fear may result in behavioral avoidance leading to disuse, disability, and depression; whereas confrontation of avoided activities may result in a reduction of fear over time and reengagement with activities of daily living. Although there are several measures to assess pain-related fear among adults with chronic pain, none exist for children and adolescents. The aim of the current study was to develop a new tool to assess avoidance and fear of pain with pediatric chronic pain patients: the Fear of Pain Questionnaire, child report (FOPQ-C), and Fear of Pain Questionnaire, parent proxy report (FOPQ-P). After initial pilot testing, the FOPQ-C and FOPQ-P were administered to 299 youth with chronic pain and their parents at an initial multidisciplinary pain treatment evaluation. The FOPQ demonstrated very strong internal consistency of .92 for the child and parent versions. One-month stability estimates were acceptable and suggested responsivity to change. For construct validity, the FOPQ correlated with generalized anxiety, pain catastrophizing, and somatization. Evidence of criterion-related validity was found with significant associations for the FOPQ with pain, healthcare utilization, and functional disability. These results support the FOPQ as a psychometrically sound measure. ⋯ Pain-related fear plays an important role in relation to emotional distress and pain-related disability among children and adolescents with chronic pain. Identification of patients with high levels of fear avoidance of pain with the FOPQ will inform how to proceed with psychological and physical therapy interventions for chronic pain.
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Diffuse Noxious Inhibitory Controls (DNIC) involves application of a noxious stimulus outside the testing site to produce analgesia. In human subjects with a variety of chronic pain conditions, DNIC is less effective; however, in animal studies, DNIC is more effective after tissue injury. While opioids are involved in DNIC analgesia, the pathways involved in this opioid-induced analgesia are not clear. The aim of the present study was to test the effectiveness of DNIC in inflammatory muscle pain, and to study which brainstem sites mediate DNIC- analgesia. Rats were injected with 3% carrageenan into their gastrocnemius muscle and responses to cutaneous and muscle stimuli were assessed before and after inflammation, and before and after DNIC induced by noxious heat applied to the tail (45 °C and 47 °C). Naloxone was administered systemically, into rostral ventromedial medulla (RVM), or bilaterally into the medullary reticularis nucleus dorsalis (MdD) prior to the DNIC-conditioning stimuli. DNIC produced a similar analgesic effect in both acute and the chronic phases of inflammation reducing both cutaneous and muscle sensitivity in a dose-dependent manner. Naloxone systemically or microinjected into the MdD prevented DNIC-analgesia, while naloxone into the RVM had no effect on DNIC analgesia. Thus, DNIC analgesia involves activation of opioid receptors in the MdD. ⋯ The current study shows that DNIC activates opioid receptors in the MdD, but not the RVM, to produce analgesia. These data are important for understanding clinical studies on DNIC as well as for potential treatment of chronic pain patients.
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Evidence suggests that gamma-aminobutyric acid (GABA) signalling in the basolateral amygdala (BLA) is involved in pain, fear, and fear-conditioned analgesia (FCA). In this study, we investigated the effects of intra-BLA administration of the GABA(A) receptor agonist muscimol on the expression of conditioned-fear, formalin-evoked nociception, and fear-conditioned analgesia in rats, and the associated alterations in brain regional expression of the immediate early gene product and marker of neuronal activity, c-Fos. Formalin-evoked nociceptive behavior, conditioned-fear and fear-conditioned analgesia were apparent in animals receiving intra-BLA saline. Intra-BLA muscimol suppressed fear behavior and prevented fear-conditioned analgesia, but had no significant effect on the expression of formalin-evoked nociception. The suppression of fear behavior by intra-BLA muscimol was associated with increased c-Fos expression in the central nucleus of the amygdala (CeA) and throughout the periaqueductal grey (PAG). These intra-BLA muscimol-induced increases in c-Fos expression were abolished in rats receiving intraplantar formalin injection. These data suggest that alterations in neuronal activity in the CeA and PAG as a result of altered GABAergic signalling in the BLA may be involved in the behavioral expression of fear and associated analgesia. Furthermore, these alterations in neuronal activity are susceptible to modulation by formalin-evoked nociceptive input in a state-dependent manner. ⋯ The expression of learned fear and associated analgesia are under the control of GABA(A) receptors in the basolateral amygdala, through a mechanism which may involve altered neuronal activity in key components of the descending inhibitory pain pathway. The results enhance our understanding of the neural mechanisms subserving fear-pain interactions.
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Substantial literature suggests that diverse biological, psychological, and sociocultural mechanisms account for differences by race and ethnicity in the experience, epidemiology, and management of pain. Many studies have examined differences between Whites and minority populations, but American Indians (AIs), Alaska Natives (ANs), and Aboriginal peoples of Canada have been neglected both in studies of pain and in efforts to understand its biopsychosocial and cultural determinants. This article reviews the epidemiology of pain and identifies factors that may affect clinical assessment and treatment in these populations. We searched for peer-reviewed articles focused on pain in these populations, using PubMed, CINAHL, Cochrane, and the University of New Mexico Native Health Database. We identified 28 articles published 1990 to 2009 in 3 topic areas: epidemiology of pain, pain assessment and treatment, and healthcare utilization. A key finding is that AI/ANs have a higher prevalence of pain symptoms and painful conditions than the U.S. general population. We also found evidence for problems in provider-patient interactions that affect clinical assessment of pain, as well as indications that AI/AN patients frequently use alternative modalities to manage pain. Future research should focus on pain and comorbid conditions and develop conceptual frameworks for understanding and treating pain in these populations. ⋯ We reviewed the literature on pain in AI/ANs and found a high prevalence of pain and painful conditions, along with evidence of poor patient-provider communication. We recommend further investigation of pain and comorbid conditions and development of conceptual frameworks for understanding and treating pain in this population.
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Preliminary reports suggest that acceptance of pain is an important construct when assessing and treating adolescents with chronic pain. Although the Chronic Pain Acceptance Questionnaire, Adolescent version (CPAQ-A) appears to be a promising tool, it has been evaluated in only 1 study. The current results present a confirmatory analysis of the CPAQ-A and validity data collected independently from the developers of the scale. A sample of 109 adolescents with chronic pain completed the CPAQ-A, as well as measures of pain characteristics, functional impairment, depression, anxiety, and pain self-efficacy. Results of the confirmatory factor analysis indicate the previously reported 2-factor solution provides a good fit to the data, and has acceptable internal consistency. The CPAQ-A correlated strongly with disability, depression, anxiety, and self-efficacy. It correlated only moderately with pain intensity and was not correlated with pain frequency or duration of pain. When entered last into a hierarchical regression model predicting disability, acceptance accounted for more variance than pain intensity, depression, anxiety, and self-efficacy. Results supported the internal consistency and validity of the CPAQ-A as a measure of pain acceptance in this sample of adolescents with chronic pain. Use of the CPAQ-A may provide valuable insight into the manner in which adolescents adapt to chronic pain and can guide acceptance-based treatment. ⋯ This article strengthens the psychometric support for a measure of chronic pain acceptance in adolescents. Acceptance-based treatment has been shown to reduce disability in preliminary research targeting adolescents with chronic pain; the CPAQ-A may be useful for assessing the degree to which acceptance-based approaches may be indicated for a given patient.