Pain
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Multicenter Study
Health-related quality of life in 975 patients with Complex Regional Pain Syndrome type 1.
There are limited data available on health-related quality of life (QoL) in patients with complex regional pain syndrome (CRPS). In the present study we examined QoL in 975 CRPS patients attending 6 different clinics in the Netherlands. QoL was assessed using the MOS 36-Item Short-Form Health Survey (SF-36) with the Mental Health Summary Score (MHS) and the Physical Health Summary Score (PHS) as dependent variables. ⋯ A comparison with data available from the literature shows that CRPS patients generally report poorer QoL than patients with other chronic pain conditions, particularly in the physical domains. Pain correlated moderately with QoL and therefore deserves ongoing attention by physicians. Finally, patients meeting the diagnostic Budapest criteria have lower QoL scores than patients meeting the Orlando criteria, highlighting the impact of different sets of criteria on population characteristics.
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Randomized Controlled Trial
The Relationship between Fear of Social and Physical Threat and their Effects on Social Distress and Physical Pain Perception.
Past research has found that measuring individuals' fear of pain predicts their physical pain perceptions: those reporting higher levels of fear of pain report higher levels of pain. We investigated links between fear of social threat and fear of physical pain, testing whether these fears predict responses to social distress and physical pain. In 3 studies, we found that fear of social and physical threat were related yet distinct psychological constructs (study 1), that fear of social (but not physical) threat predicted the perception of social distress (study 2), and that fear of physical (but not social) pain predicted the perception of physical pain (study 3). ⋯ However, we also found that these effects were specific, such that each type of fear uniquely predicted the experience of the same type of distress. We argue that timely identification of high levels of social threat-related fear is critical for identifying individuals who will benefit most from preventative interventions aimed to limit negative cycles of high avoidance and increased social threat perception. Furthermore, our work sets a boundary condition to pain overlap theory by showing that high levels of fear of one type of pain (e.g., social) are specifically linked to increased perception of that particular type of pain (e.g., social) but not the other (e.g., physical).
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Systemic artemin promotes regeneration of dorsal roots to the spinal cord after crush injury. However, it is unclear whether systemic artemin can also promote peripheral nerve regeneration, and functional recovery after partial lesions distal to the dorsal root ganglion (DRG) remains unknown. In the present investigation, male Sprague Dawley rats received axotomy, ligation, or crush of the L5 spinal nerve or sham surgery. ⋯ Sciatic and intradermal administration of dextran or cholera toxin B distal to the crush injury site resulted in labeling of neuronal profiles in the L5 DRG, suggesting regeneration functional restoration of nonmyelinated and myelinated fibers across the injury site into cutaneous tissue. Artemin also diminished ATF3 and caspase 3 expression in the L5 DRG, suggesting persistent neuroprotective actions. A limited period of artemin treatment elicits disease modification by promoting sensory reinnervation of distal territories and restoring preinjury sensory thresholds.
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α2-Adrenoceptors are widely distributed throughout the central nervous system (CNS) and the systemic administration of α2-agonists such as dexmedetomidine produces clinically useful, centrally mediated sedation and analgesia; however, these same actions also limit the utility of these agents (ie, unwanted sedative actions). Despite a wealth of data on cellular and synaptic actions of α2-agonists in vitro, it is not known which neuronal circuits are modulated in vivo to produce the analgesic effect. To address this issue, we made in vivo recordings of membrane currents and synaptic activities in superficial spinal dorsal horn neurons and examined their responses to systemic dexmedetomidine. ⋯ In the brainstem, low doses of systemic dexmedetomidine produced an excitation of locus coeruleus neurons. These results suggest that systemic α2-adrenoceptor stimulation may facilitate inhibitory synaptic responses in the superficial dorsal horn to produce analgesia mediated by activation of the pontospinal noradrenergic inhibitory system. This novel mechanism may provide new targets for intervention, perhaps allowing analgesic actions to be dissociated from excessive sedation.
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Pain is a highly personal experience that varies substantially among individuals. In search of an anatomical correlate of pain sensitivity, we used voxel-based morphometry to investigate the relationship between grey matter density across the whole brain and interindividual differences in pain sensitivity in 116 healthy volunteers (62 women, 54 men). Structural magnetic resonance imaging (MRI) and psychophysical data from 10 previous functional MRI studies were used. ⋯ No regions showed a positive relationship to pain sensitivity. These structural variations occurred in areas associated with the default mode network, attentional direction and shifting, as well as somatosensory processing. These findings underscore the potential importance of processes related to default mode thought and attention in shaping individual differences in pain sensitivity and indicate that pain sensitivity can potentially be predicted on the basis of brain structure.