Pain
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Irritable bowel syndrome (IBS) is a common gastrointestinal disorder characterized by recurring abdominal pain associated with alterations in bowel habits. We hypothesized that patients with chronic visceral pain associated with IBS may have microstructural differences in the brain compared with healthy control subjects (HCs), indicative of long-term neural reorganization of chronic pain pathways and regions associated with sensory integration. In the current study we performed population-based voxel-wise diffusion tensor imaging (DTI) comparisons and probabilistic tractography in a large sample of phenotyped patients with IBS (n=33) and in HCs (n=93). ⋯ Sex differences in FA and MD were also observed in the patients but not in HCs. Probabilistic tractography in patients confirmed a higher degree of connectivity between the thalamus and prefrontal cortex, as well as between the medial dorsal thalamic nuclei and anterior cingulate cortex, and a lower degree of connectivity between the GP and thalamus. Together, these results support the hypothesis that patients with chronically recurring visceral pain from IBS have long-term microstructural changes within the brain, particularly in regions associated with integration of sensory information and corticothalamic modulation.
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Previous research in health and disease has shown that exposure to pain changes the density of cortical grey matter (GM). Such structural changes of the brain might, however, depend crucially on how this pain experience is evaluated and processed in the brain. In the present study we aimed to detect pain-rating patterns and underlying GM changes after the application of repetitive painful stimulation using voxel-based morphometry (VBM). ⋯ By contrast, pain habituaters did not show any density changes in the GM. Depending on the individual perception of pain during the time course of stimulation, the repetitive application of painful stimuli changed the GM density in pain-processing brain regions exclusively in those subjects who were characterised by the lack of habituation. Because VBM studies investigating patients experiencing chronic pain observed similar decreases in GM density and increasing pain ratings over time, the sensitisers in our study may have a higher vulnerability to developing chronic pain syndromes in later life.
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Primary and metastatic cancers that affect bone are frequently associated with severe and intractable pain. The mechanisms underlying the development of bone cancer pain are largely unknown. In this study, we first demonstrated that a functional upregulation of P2X3 receptors in dorsal root ganglion (DRG) neurons is closely associated with the neuronal hyperexcitability and the cancer-induced bone pain in MRMT-1 tumor cell-inoculated rats. ⋯ Taken together, these results suggest that functional upregulation of P2X3 receptors by VILIP-1 in DRG neurons contributes to the development of cancer-induced bone pain in MRMT-1 rats. Hence, P2X3 receptors and VILIP-1 could serve as potential targets for therapeutic interventions in cancer patients for pain management. Pharmacological blockade of P2X3 receptors or knockdown of VILIP-1 in DRGs would be used as innovative strategies for the treatment of bone cancer pain.
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The lack of efficacy of rehabilitative approaches to the management of chronic whiplash-associated disorders (WAD) may be in part due to heterogeneity of the clinical presentation of this patient population. The aim of this study was to identify homogeneous subgroups of patients with chronic WAD on the basis of symptoms of PTSD and sensory hypersensitivity and to compare the clinical presentation of these subgroups. Successive k-means cluster analyses using 2, 3 and 4 cluster solutions were performed by using data for 331 (221 female) patients with chronic (>3 months) WAD. ⋯ The nPnH cluster was the largest cluster, comprising 43.5% of the sample. The PH cluster had significantly worse disability, pain intensity, self-reported mental health status and cervical range of motion in comparison to the nPnH and nPH clusters. These data provide further evidence of the heterogeneity of the chronic WAD population and the association of a more complex clinical presentation with higher disability and pain in this patient group.