The journal of pain : official journal of the American Pain Society
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Clinical Trial
Pain-related attentional biases: the importance of the personal relevance and ecological validity of stimuli.
The literature regarding pain-related attentional biases is currently marked by considerable inconsistency. The primary aim of the present study was to examine whether 2 stimulus-related factors may be important to the detection of pain-related attentional biases: 1) the personal relevance of stimuli; and 2) their ecological validity. To do this, the present research compared the ability of a word-based dot-probe task (ie, lower ecological validity) and picture-based dot-probe task (ie, higher ecological validity) to detect attentional biases using generally selected (ie, lower personal relevance) and idiosyncratically selected stimuli (ie, higher personal relevance). To do this, the present study used a large sample of chronic pain patients and matched pain-free individuals. Attentional biases were found among both chronic pain patients and pain-free individuals for idiosyncratically selected pictorial stimuli (ie, highest ecological validity and personal relevance) but not for generally selected pictorial stimuli or for pain-related word stimuli, irrespective of whether they were idiosyncratically or generally selected. These biases were found to stem from vigilance for pain-related stimuli. Overall, the findings of the present study suggest that similar pain-related attentional biases can be found among both pain-free individuals and chronic pain patients and that stimulus-related factors may be important to the detection of those biases. ⋯ To date, research examining pain-related attentional biases has yielded inconsistent results. The present study sought to examine 2 stimulus-related factors often identified for their potential to influence the consistency of findings. The findings of this study highlight the importance of considering stimulus-related factors when designing and interpreting pain-related dot-probe research.
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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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Comparative Study Clinical Trial
The relationship between physical activity and brain responses to pain in fibromyalgia.
The relationship between physical activity and central nervous system mechanisms of pain in fibromyalgia (FM) is unknown. This study determined whether physical activity was predictive of brain responses to experimental pain in FM using functional magnetic resonance imaging (fMRI). Thirty-four participants (n = 16 FM; n = 18 Control) completed self-report and accelerometer measures of physical activity and underwent fMRI of painful heat stimuli. In FM patients, positive relationships (P < .005) between physical activity and brain responses to pain were observed in the dorsolateral prefrontal cortex, posterior cingulate cortex, and the posterior insula, regions implicated in pain regulation. Negative relationships (P < .005) were found for the primary sensory and superior parietal cortices, regions implicated in the sensory aspects of pain. Greater physical activity was significantly (P < .05) associated with decreased pain ratings to repeated heat stimuli for FM patients. A similar nonsignificant trend was observed in controls. In addition, brain responses to pain were significantly (P < .005) different between FM patients categorized as low active and those categorized as high active. In controls, positive relationships (P < .005) were observed in the lateral prefrontal, anterior cingulate, and superior temporal cortices and the posterior insula. Our results suggest an association between measures of physical activity and central nervous system processing of pain. ⋯ Our data suggest that brain responses to pain represent a dynamic process where perception and modulation co-occur and that physical activity plays a role in balancing these processes. Physically active FM patients appear to maintain their ability to modulate pain while those who are less active do not.
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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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A large number of oncology patients with bone metastasis report significant and often unrelieved pain that is associated with reduced quality of life and impaired functional status. Our research team previously assessed the efficacy of a tailored self-care psychoeducational intervention to improve pain management in these patients. Samplewide analyses demonstrated improvements in pain intensity and analgesic prescriptions. However, substantial interindividual variability was observed within the intervention group. In the current paper, hierarchical linear modeling (HLM) was used to determine factors that contributed to variability in pain intensity and analgesic prescription and intake in the sample of patients who participated in the intervention. Specifically, HLM analyses identified demographic, clinical, and psychological characteristics that predicted variation in pain intensity and analgesic prescription and intake at baseline (intercepts) and over the course of the 6-week study (trajectories). Awareness of these predictors may be particularly useful for the identification of patients who would benefit most from this type of intervention. Furthermore, these findings highlight specific aspects of the intervention that may be modified in order to further improve pain management in these patients. ⋯ This paper describes the application of HLM to explain interindividual variability in pain and analgesic outcomes among oncology outpatients with metastatic bone pain who participated in a psychoeducational intervention to improve pain management. Findings identify particularly responsive subgroups, areas for improvement to the intervention, and targets for future intervention.