Pain
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Randomized Controlled Trial
Duloxetine in patients with central neuropathic pain caused by spinal cord injury or stroke: a randomized, double-blind, placebo-controlled trial.
The mechanisms underlying central neuropathic pain are poorly understood. Pain inhibitory mechanisms including sertononergic and norepinephrine systems may be dysfunctional. In this randomized, double-blinded, placebo-controlled trial we evaluated the effects of duloxetine on pain relief (spontaneous pain and evoked pain), tolerability, health status, and quality of life in patients with central pain related to cerebrovascular lesions or spinal cord lesions. ⋯ No significant differences were observed in the other domains of the SF36, the Pain Disability Index, and the EQ-5D. While this trial showed no significant effect on pain intensity, duloxetine revealed a biologic effect. It would be worthwhile to suspend our judgement and to perform more studies to evaluate the role of duloxetine in modulation of the symptoms of central neuropathic pain.
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The fear avoidance model of pain (FAM) conceptualizes pain catastrophizing as the cognitive antecedent of pain-related fear, and pain-related fear as the emotional antecedent of depression and disability. The FAM is essentially one of mediation whereby pain-related fear becomes the process by which depression or disability ensue. However, emerging literature suggests that pain catastrophizing, pain-related fear, and depression might be at least partially distinct in their prediction of different pain-related outcomes. ⋯ After controlling for pain intensity and FAM variables, pain self-efficacy was shown to be a unique predictor of medication use. Implications for the FAM and the clinical management of musculoskeletal pain conditions are discussed. Unique relationships were found between pain catastrophizing and long-term pain intensity, between fear of movement and long-term work disability, and between pain self-efficacy and medication use at one-year follow-up.
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Randomized Controlled Trial
Pain tests provoke modality-specific cardiovascular responses in awake, unrestrained rats.
Nociception modulates heart rate (HR) and mean arterial pressure (MAP), suggesting their use of HR and MAP as indicators of pain in animals. We explored this with telemetric recording in unrestrained control and neuropathic (spinal nerve ligation) rats. Plantar stimulation was performed emulating techniques commonly used to measure pain, specifically brush stroke, von Frey fiber application, noxious pin stimulation, acetone for cooling, and radiant heating, while recording MAP, HR, and specific evoked somatomotor behaviors (none; simple withdrawal; or sustained lifting, shaking, and grooming representing hyperalgesia). ⋯ Heating, consistently depressed HR and MAP, independent of behavior. Other than a greater HR response to pin in animals made hyperalgesic by injury, cardiovascular events evoked by stimulation did not differ between control and neuropathic animals. We conclude that (a) thermoregulation rather than pain may dominate responses to heat and cooling stimuli; (b) brush and cooling stimuli may be perceived and produce cardiovascular activation without nocifensive withdrawal; (c) sensations that produce hyperalgesia behavior are accompanied by greater cardiovascular activation than those producing simple withdrawal; and (d) von Frey stimulation lacks cardiovascular evidence of nociception except when hyperalgesia behavior is evoked.
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Chronic pain not only interferes with daily activities, it may also have a negative impact on the perceived integrity of one's self through self-discrepancies. Self-discrepancies are experienced distances between the actual self and self-guides that can exist from 2 perspectives (ie, own and other). Self-discrepancies are associated with negative mood states and incite self-regulatory behavior in order to reduce these discrepancies. ⋯ In contrast to expectations, none of the other self-discrepancies was related to activity patterns. Of interest was that avoidance, but not persistence behavior, was predictive of higher levels of disability and lower levels of quality of life. Support is provided for the role of self-discrepancies in the emotional well-being and behavioural patterns of patients with chronic low back pain.
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We determined rates and predictors of future development of fibromyalgia in patients with rheumatoid arthritis (RA). After excluding patients with fibromyalgia and those with high levels of fibromyalgia symptoms (fibromyalgianess score>10) at baseline, we studied fibromyalgia development in 9739 RA patients during 42,591 patient-years of follow-up. We defined fibromyalgia using a modification of the ACR 2010 fibromyalgia criteria. ⋯ Demographic plus RA variables (C=0.720) and demographic plus fibromyalgia variables (C=0.765), and all predictors (C=0.782) increased accuracy. Clinically important hazard ratios were noted for cognition, depression, comorbidity, and high levels of RA and FM continuous variables Overall, study results indicate that multiple, inter-correlated factors that include social disadvantage, psychological distress, comorbidity, RA severity, and fibromyalgia variables predict future development of fibromyalgia, but there is little evidence of the effect of underlying causes. After diagnosis, patients move in both directions across the diagnostic criteria cut points.