European journal of pain : EJP
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The aim of this study was to investigate the effect of unilateral limb pain on sensitivity to pain on each side of the forehead. In the first experiment, pressure-pain thresholds and sharpness sensations were assessed on each side of the forehead in 45 healthy volunteers before and after a 10 degrees C cold pressor of the hand and in 18 controls who were not subjected to the cold pressor. In a second experiment, forehead sensitivity was assessed in 32 healthy volunteers before and after a 2 degrees C cold pressor. ⋯ The locus coeruleus inhibits ipsilateral nociceptive activity in dorsal horn neurons during limb inflammation, and thus may have mediated the ipsilateral component of analgesia. Pain-evoked changes in forehead sensitivity differed for sharpness and pressure, possibly due to separate thalamic or cortical representations of cutaneous and deep tissue sensibility. These findings suggest that several mechanisms act concurrently to influence pain sensitivity at sites distant from a primary site of painful stimulation.
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Attention management is often included in cognitive-behavioural treatments (CBT). The aim of this study was to evaluate the effects of attention management strategies in the treatment for chronic pain. The present pilot study consisted of six weekly 90-min treatment sessions and was based on a CBT attention management manual describing techniques such as attention diversion, imagery and mindfulness exercises. ⋯ Reduction in pain-related interference and anxiety remained at the 6-month follow-up. The results indicate that attention control skills can be a useful method to reduce anxiety in the short term. Clinical implications of the results are discussed.
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Although persistent postherniotomy occurs in 5-10% of patients, pathogenic mechanisms remain debatable. Since pre-operative pain has been demonstrated to be a risk factor for persistent postherniotomy pain, pre-operative alterations in nociceptive function may be a potential pathogenic mechanism. ⋯ Pre-operative groin hernia pain is not related to findings of hyperalgesia or other changes in sensory function that may support pain-induced pre-operative neuroplasticity as a pathogenic mechanism for the development of persistent postherniotomy pain.
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Recent research suggests bi-directional interactions between the experience of pain and the process of sleep; pain interferes with the ability to obtain sleep, and disrupted sleep contributes to enhanced pain perception. Our group recently reported, in a controlled experimental study, that sleep fragmentation among healthy adults resulted in subsequent decrements in endogenous pain inhibition. The present report follows up that observation by extending this line of research to a sample of patients experiencing persistent pain. ⋯ We assessed whether individual differences in sleep continuity and/or architecture were related to diffuse noxious inhibitory controls (DNIC), a measure of central nervous system pain inhibition. Among 53 TMD patients, higher sleep efficiency and longer total sleep time were positively associated with better functioning of DNIC (r=0.42-0.44, p<0.01; ps<0.05 for the multivariate analyses). These results suggest the possibility that disrupted sleep may serve as a risk factor for inadequate pain-inhibitory processing and hint that aggressive efforts to treat sleep disturbance early in the course of a pain condition might be beneficial in reducing the severity or impact of clinical pain.
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Nitric oxide, which has been implicated in the development of hyperalgesia in the spinal system, has not been systematically studied in the trigeminal system, especially in the context of inflammatory muscle pain condition. In this study, we investigated the functional role of centrally released nitric oxide in the pathogenesis of orofacial muscle pain. Specifically, we examined the contribution of neuronal, inducible and endothelial nitric oxide synthases, nNOS, iNOS and eNOS, respectively, in mediating masseter hypersensitivity under acute inflammatory condition. ⋯ The expression of all three nitric oxide synthases was significantly up-regulated 30-60 min following capsaicin stimulation, which paralleled the time course of the development of capsaicin-induced masseter hypersensitivity. Pretreatment with each NOS inhibitor significantly attenuated the masseter hypersensitivity. These data showed that all three NOS in the Vc are functionally important for the development of craniofacial muscle hyperalgesia and suggest that the three NOS are closely orchestrated to regulate the level of nitric oxide under normal and pathologic conditions.