European journal of pain : EJP
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Spinal cord stimulation (SCS) has been shown to provide pain relief in painful diabetic polyneuropathy (PDPN). As the vasculature system plays a great role in the pathophysiology of PDPN, a potential beneficial side-effect of SCS is peripheral vasodilation, with high frequency (HF) SCS in particular. We hypothesize that HF-SCS (500 Hz), compared with conventional (CON) or low frequency (LF)-SCS will result in increased alleviation of mechanical hypersensitivity in chronic experimental PDPN. ⋯ This study evaluates the effect of SCS frequency (5-500 Hz) on mechanical hypersensitivity in the chronic phase of experimental PDPN. High frequency (500 Hz) - SCS resulted in a delayed effect- on pain-related behavioural outcome in chronic PDPN.
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The TRP channel ankyrin type 1 (TRPA1) is a nonselective cation channel known to be activated by environmental irritants, cold and endogenous mediators of inflammation. Activation of TRPA1 in trigeminal afferents innervating meningeal structures has recently been suggested to be involved in the generation of headaches. ⋯ Sole activation of TRPA1 receptor channels increases the activation threshold but does not cause propagated action potentials in meningeal afferents. TRPA1 agonists cause CGRP release from rodent dura mater. Peripheral TRPA1 receptors may have a pronociceptive function in trigeminal nociception only in combination with TRPV1.
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Review
Brain changes associated with cognitive and emotional factors in chronic pain: A systematic review.
An emerging technique in chronic pain research is MRI, which has led to the understanding that chronic pain patients display brain structure and function alterations. Many of these altered brain regions and networks are not just involved in pain processing, but also in other sensory and particularly cognitive tasks. Therefore, the next step is to investigate the relation between brain alterations and pain related cognitive and emotional factors. ⋯ In contrast to pain catastrophizing, evidence on anxiety and depressive symptoms shows no clear association with brain characteristics. However, all included cognitive or emotional factors showed significant associations with resting state fMRI data, providing that even at rest the brain reserves a certain activity for these pain-related factors. Brain changes associated with illness perceptions, pain attention, attitudes and beliefs seem to receive less attention in literature.
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Generalization of fear of movement-related pain across novel but similar movements can lead to fear responses to movements that are actually not associated with pain. The peak-shift effect describes a phenomenon whereby particular novel movements elicit even greater fear responses than the original pain-provoking movement (CS+), because they represent a more extreme version of the CS+. There is great variance in the propensity to generalize as well as the speed of extinction learning when these novel movements are not followed by pain. It can be argued that this variance may be associated with executive function capacity, as individuals may be unable to intentionally inhibit fear responses. This study examined whether executive function capacity contributes to generalization and extinction of generalization as well as peak-shift of conditioned fear of movement-related pain and expectancy. ⋯ Low inhibitory capacity is not associated with slower generalization, but extinction of fear generalization. Fear elicited by a novel safe movement, situated outside the CS+/- continuum on the CS+ side, can be as strong as to the original stimulus predicting the pain-onset.
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Individual patient data (IPD) meta-analysis of existing randomized controlled trials (RCTs) is a promising approach to achieving sufficient statistical power to identify sub-groups. We created a repository of IPD from multiple low back pain (LBP) RCTs to facilitate a study of treatment moderators. Due to sparse heterogeneous data, the repository needed to be robust and flexible to accommodate millions of data points prior to any subsequent analysis. ⋯ A flexible adaptive database for pain studies that can easily be expanded for future researchers to map, transform and upload their data in a safe and secure environment. The data are standardized and harmonized which will facilitate future requests from other researchers for secondary analyses.