Pain
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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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Recent evidence suggests that emotional picture-viewing is a reliable method of engaging descending modulation of spinal nociception. The present study attempted to replicate these findings and determine the effect of noxious stimulus predictability. Participants viewed pictures from the International Affective Picture System (IAPS), during which pain and nociceptive flexion reflexes (NFR) were elicited by electric shocks delivered to the sural nerve. ⋯ However, descending modulation could not be detected in NFRs resulting from predictable noxious stimuli. Although preliminary, this study implies that separate mechanisms are responsible for emotional modulation of nociception at spinal vs. supraspinal levels, and that predictable noxious events may disengage modulation at the spinal level. The current paradigm could serve as a useful tool for studying descending modulation.
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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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Histamine, substance P, serotonin and bradykinin were applied by iontophoresis to lesional and visually non-lesional skin of 14 patients with atopic dermatitis, and normal skin of 15 healthy volunteers. Itch could be evoked by light stroking of skin with a cotton swab (alloknesis) in all lesional skin sites, but not in non-lesional or normal skin. Substances were applied in the same skin area before and 3 h after administration of placebo or antihistamine (olopatadine hydrochloride: H1-receptor-blocker). ⋯ Histamine- and substance P-induced itch was almost completely suppressed by antihistamines, whereas bradykinin- and serotonin-induced itch was not. This suggests that substance P is a histamine-dependent pruritogen also in lesional skin under sensitized conditions but that bradykinin and serotonin are histamine-independent pruritogens in lesional skin. It is concluded that serotonin and bradykinin, classic endogenous algogens, can turn into potent histamine-independent pruritogens in lesional skin of atopic dermatitis.