Pain
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A significant number of patients who have had surgery for lumbosacral radicular syndrome still have a reduced work capacity several months later. In a prospective cohort study of 182 people who underwent lumbar disc surgery, we determined the predictive value of preoperatively measured cognitive-behavioral and work-related factors on work capacity 6 months after surgery. ⋯ Specifically, fear of movement/(re)injury, more passive pain coping, and higher physical work-load predicted reduced work capacity in multiple logistic regression analyses, taking into account the role of a wide range of control variables including demographic variables, preoperative disability and pain intensity, neurological deficits, intake of analgesics, duration of complaints, and pain intensity 3 days postoperatively. The study supports the need to develop and evaluate preoperative risk screening measures that include both cognitive-behavioral and work-related factors and to evaluate the effectiveness of cognitive-behavioral and work-related interventions in patients at risk of reduced work capacity after surgery for LRS.
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Low back pain is considered to fluctuate over time, and related prognostic factors may behave similarly, therefore classification of prognosis may be affected by timing of assessment. We aimed to investigate the implications of timing of assessment of prognosis in low back pain. In a prospective cohort of primary care low back pain consulters aged 30-59 years, 359 returned questionnaires at baseline, one-month and one-year. ⋯ Presence of the indicators at both time points was associated with even higher risk; people with persistent high pain intensity had 15 times the risk of a poor outcome (relative risk 15.1; 95% confidence interval 6.7-33.8) compared with people not reporting high pain at either point. Combining information on prognostic indicators from two time points provides better classification of low back pain patients' eventual outcome than a single measurement alone. This increased accuracy in predicting prognosis is relevant to both clinical and research practice.
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Selective activation of the peripheral cannabinoid receptor 1 (CB1R) has been shown to suppress neuropathic pain symptoms in rodents. However, relatively little is known about changes in CB1R and its endogenous ligands during development or maintenance of neuropathic pain. Using immunohistochemistry, Western blot, real-time reverse transcription polymerase chain reaction, as well as liquid chromatography/mass spectrometry, we studied the changes in CB1Rs and endocannabinoids N-arachidonoylethanolamine/anandamide (AEA) and 2-arachidonoylglycerol (2-AG) in rat lumbar (L4 and L5) dorsal root ganglia (DRG) after neuropathic pain induction (L5 spinal nerve ligation: SNL). ⋯ However, for these CB1R-ir neurons, we observe significant increases in percentage of TRPV1-ir cells in ipsilateral L4 DRG, and decreases in percentage of IB4- and CGRP-co-labeled cells in ipsilateral L5 DRG. Levels of both AEA and 2-AG increase significantly only in the ipsilateral L5 DRG. These results are consistent with the preserved analgesic effects of cannabinoids in neuropathic pain and provide a rational framework for the development of peripherally acting endocannabinoid-based therapeutic interventions for neuropathic pain.
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Living with chronic pain is associated with many deleterious outcomes, including a substantially increased risk of suicide. While many general risk factors for suicidal ideation and behavior have been identified, few studies have examined pain-related factors that confer increased or decreased risk for suicidality. The present study assessed individual differences in the use of pain-related coping strategies and pain-related catastrophizing as correlates of suicidal ideation in patients with chronic pain. ⋯ Demographic and other pain-related variables such as pain severity and duration were not generally robust predictors of suicidal ideation in this sample of patients with chronic pain. These are the first findings to suggest a unique (e.g., independent of pain severity or depressive symptomatology) association between pain-coping strategies and suicide-related cognitions in the context of chronic pain. Further research in this area, including the addition of suicide prevention materials to pain-coping skills training programs, may benefit large numbers of individuals who are at elevated suicide risk as a consequence of chronic pain.
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Functional magnetic resonance imaging (fMRI) of blood oxygen level dependent (BOLD) haemodynamic responses was used to study the effects of the noxious substance capsaicin on whole brain activation in isofluorane anaesthetised rats. Rats (n=8) received intradermal injection of capsaicin (30 microg/5 microl), or topical cream (0.1%) capsaicin and BOLD responses were acquired for up to 120 min. Effects of capsaicin versus placebo cream treatment on the BOLD response to a 15 g mechanical stimulus applied adjacent to the site of cream application were also studied. ⋯ Capsaicin also produced increases in BOLD signal intensity in other regions that contribute to pain processing, such as the parabrachial nucleus and superior colliculus. Mechanical stimulation in capsaicin-treated rats, but not placebo-treated rats, induced a significant decrease in BOLD signal intensity in the PAG (p<0.001). These data demonstrate that the noxious substance capsaicin produces brain activation in the midbrain regions and reveals the importance of the PAG in central sensitization.