Pain
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The relationship between persistent pain and self-directed, non-reactive awareness of present-moment experience (i.e., mindfulness) was explored in one of the dominant psychological theories of chronic pain - the fear-avoidance model[53]. A heterogeneous sample of 104 chronic pain outpatients at a multidisciplinary pain clinic in Australia completed psychometrically sound self-report measures of major variables in this model: Pain intensity, negative affect, pain catastrophizing, pain-related fear, pain hypervigilance, and functional disability. Two measures of mindfulness were also used, the Mindful Attention Awareness Scale [4] and the Five-Factor Mindfulness Questionnaire [1]. ⋯ Hierarchical multiple regression analysis showed that mindfulness uniquely predicts pain catastrophizing when other variables are controlled, and moderates the relationship between pain intensity and pain catastrophizing. This is the first clear evidence substantiating the strong link between mindfulness and pain catastrophizing, and suggests mindfulness might be added to the fear-avoidance model. Implications for the clinical use of mindfulness in screening and intervention are discussed.
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This case report presents data regarding endogenous opioid analgesia in a healthy female subject prior to developing chronic pain, and again 4 and 13 months following onset of chronic daily back pain. At each assessment period, the subject underwent identical protocols involving two sessions one week apart with randomized double-blind crossover administration of saline placebo and naloxone, an opioid antagonist. Each session included a 5-min anger recall interview, followed by finger pressure and ischemic acute pain tasks. ⋯ The mean magnitude of this opioid blockade effect for the finger pressure task exceeded the 99% confidence interval for the healthy control population based on a previous study using a similar opioid blockade protocol [4]. At 13-month follow-up, naloxone produced a mean 45% decrease in acute pain ratings compared to placebo, arguing against presence of endogenous opioid analgesia. Although results must be interpreted cautiously, findings are consistent with the hypothesis that chronic pain may initially be associated with upregulation of endogenous opioid analgesic systems which then may become dysfunctional over time.
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There is an increasing number of studies of acceptance, mindfulness, and values-based action in relation to chronic pain. Evidence from these studies suggests that these processes may be important for reducing the suffering and disability arising in these conditions. Taken together these processes entail an overarching process referred to as "psychological flexibility." While these processes have been studied in people with chronic pain contacted in specialty treatment centers, they have not yet been investigated in primary care. ⋯ In these regression equations pain intensity accounted for an average of 9.2% of variance while psychological flexibility accounted for 24.1%. These data suggest that psychological flexibility may reduce the impact of chronic pain in patients with low to moderately complex problems outside of specialty care. Due to a particularly conservative recruitment strategy the overall response rate in this study was low and the generality of these results remains to be established.
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Questions remain concerning effectiveness and risks of spinal cord stimulation (SCS) for chronic back and leg pain after spine surgery ("failed back surgery syndrome" [FBSS]). This prospective, population-based controlled cohort study evaluated outcomes of workers' compensation recipients with FBSS who received at least a trial of SCS (SCS group, n=51) versus those who (1) were evaluated at a multidisciplinary pain clinic and did not receive SCS (Pain Clinic, n=39) or (2) received neither SCS nor pain clinic evaluation (Usual Care, n=68). Patients completed measures of pain, function, medication use, and work status at baseline and 6, 12, and 24 months later. ⋯ Patients who received a permanent spinal cord stimulator did not differ from patients who received some pain clinic treatment on the primary outcome at any follow-up (<10% successful in each group at each follow-up) and 19% had them removed within 18 months. Both trial and permanent SCS were associated with adverse events. In sum, we found no evidence for greater effectiveness of SCS versus alternative treatments in this patient population after 6 months.
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Chemical modifications of nociceptin/orphanin FQ (N/OFQ) peptide that result in increased potency and resistance to degradation have recently lead to the discovery of [(pF)Phe(4)Aib(7)Arg(14)Lys(15)]N/OFQ-NH(2) (UFP-112), a novel N/OFQ peptide (NOP) receptor agonist. The aim of this study was to investigate the pharmacological profile of intrathecally administered UFP-112 in monkeys under different behavioral assays. Intrathecal UFP-112 (1-10 nmol) dose-dependently produced antinociception against an acute noxious stimulus (50 degrees C water) and capsaicin-induced thermal hyperalgesia. ⋯ In addition, intrathecal inactive doses of UFP-112 and morphine produced significant antinociceptive effects when given in combination without increasing scratching responses. These results demonstrated that intrathecal UFP-112 produced long-lasting morphine-comparable antinociceptive effects without potential itch side effect. This study is the first to provide functional evidence that selective NOP receptor agonists such as UFP-112 alone or in conjunction with morphine may improve the quality of spinal analgesia.