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The primary objective was to investigate the prevalence of neuropathic-like pain in patients with psoriatic arthritis (PsA). Secondary outcomes were to investigate whether mood, fatigue, pain, disease severity and fibromyalgia are associated with neuropathic-like pain in PsA patients.
Learn More >To identify the differences in overall occurrence, location, and disease burden of white matter hyperintensities (WMH) in patients with sporadic hemiplegic migraine (SHM) and patients with migraine headaches.
Learn More >Preclinical studies suggest that type 2 hyperpolarization-activated cyclic nucleotide gated ion channels (HCN2) are necessary for neuropathic pain. This trial assessed the influence of ivabradine, a non-selective HCN channel blocker, on capsaicin-induced hyperalgesia and pain in healthy human subjects. An enriched population comprising subjects who developed >20cm2 of punctate hyperalgesia from topical capsaicin (0.5% cream applied onto 9cm2 area) was identified. These subjects then received ivabradine (15mg) or placebo one hour prior to capsaicin application in randomly allocated order in a crossover study. The forearm site for capsaicin alternated with each application of the cream. The interval of time from screening to the 1st and to the 2nd treatment visits were at least 3 and 5 weeks respectively to minimize carry-over effects. 55 participants were screened, of which 25 completed at least one treatment visit. Intention-to-treat hierarchical analysis revealed no significant effects of the drug on primary trial outcome, defined as a difference in effects of placebo and ivabradine on the area of punctate hyperalgesia (ivabradine – placebo: mean=3.22 cm2, 95% CI: = -4.04, 10.48, p=0.37). However, ivabradine caused a slowing of heart rate (difference of 10.10 beats per min (95% CI – 6.48, – 13.73; p-value <0.0001)). We conclude that ivabradine lacks analgesic effects in the capsaicin pain model at a dose that caused appreciable slowing of heart rate, and hence is unlikely to prove a useful analgesic in humans. More selective drugs are required to establish a role of HCN2 for pain in humans.
Learn More >To compare adverse childhood experiences (ACEs) in women with chronic pelvic pain with a control group, and describe occurrence of specific ACEs in women with chronic pelvic pain.
Learn More >To compare effectiveness of onabotulinumtoxinA and topiramate for chronic migraine (CM) prevention.
Learn More >The endogenous metabolite methylglyoxal (MG) accumulates in diabetic patients with neuropathic pain. MG could be a mediator of diabetes-induced neuropathic pain via TRPA1 activation and sensitization of the voltage-gated sodium channel subtype 1.8. In this study, we tested the algogenic and sensitizing effect of MG in healthy human subjects using intracutaneous microinjections. The involvement of C-fibers was assessed via selective A-fiber nerve block, axon-reflex-erythema and via single nerve fiber recordings in humans (microneurography). Involvement of the transduction channels TRPA1 and TRPV1 in MG-induced pain sensation was investigated with specific ion channel blockers. We showed for the first time in healthy humans that MG induces pain, axon-reflex-erythema and long-lasting hyperalgesia via the activation of C-nociceptors. Predominantly the subclass of mechano-insensitive C-fibers is activated by MG. A-fibers contribute only negligibly to the burning pain sensation. Selective harmacological blockade of TRPA1 or TRPV1 showed that TRPA1 is crucially involved in MG-induced chemical pain sensation and heat hyperalgesia. In conclusion, the ctions of MG via TRPA1 activation on predominantly mechanoinsensitive C-fibers might be involved in spontaneously perceived pain in diabetic neuropathy and hyperalgesia as well as allodynia.
Learn More >Fibromyalgia syndrome (FM) represents a great challenge for clinicians and researchers because the efficacy of currently available treatments is limited. The present study examined the efficacy of Mindfulness-Based Stress Reduction (MBSR) for reducing functional impairment as well as the role of mindfulness-related constructs as mediators of treatment outcomes for people with FM. 225 participants with FM were randomized into three study arms: MBSR plus treatment-as-usual (TAU), FibroQoL (multicomponent intervention for FM) plus TAU, and TAU alone. The primary endpoint was functional impact (measured with the Fibromyalgia Impact Questionnaire Revised), and secondary outcomes included "fibromyalginess", anxiety and depression, pain catastrophising, perceived stress and cognitive dysfunction. The differences in outcomes between groups at post-treatment assessment (primary endpoint) and 12-month follow-up were analyzed using linear mixed-effects models and mediational models through path analyses. MBSR was superior to TAU both at post-treatment (large effect sizes) and at follow-up (medium to large effect sizes), and MBSR was also superior to FibroQoL post-treatment (medium to large effect sizes), but long-term it was only modestly better (significant differences only in pain catastrophising and fibromyalginess). Immediately post-treatment, the NNT for 20% improvement in MBSR versus TAU and FibroQoL was 4.0 (95%CI= 2.1-6.5) and 5.0 (95%CI= 2.7-37.3). An unreliable NNT value of 9 (not computable 95%CI) was found for FibroQoL vs. TAU. Changes produced by MBSR in functional impact were mediated by psychological inflexibility and the mindfulness facet Acting with awareness. These findings are discussed in relation to previous studies of psychological treatments for FM.
Learn More >Spinal cord stimulation (SCS) applied between T8 and T11 segments has been shown to be effective for the treatment of chronic pain of the lower back and limbs. However, the mechanism of the analgesic effect at these medullary levels remains unclear. Numerous studies relate glial cells with development and maintenance of chronic neuropathic pain. Glial cells are electrically excitable, which makes them a potential therapeutic target using SCS. The aim of this study is to report glia to neuron ratio in thoracic segments relevant to SCS, as well as to characterize the glia cell population at these levels. Dissections from gray and white matter of posterior spinal cord segments (T8, T9, intersection T9/T10, T10 and T11) were obtained from 11 human cadavers for histological analyses. Neuronal bodies and glial cells (microglia, astrocytes and oligodendrocytes) were immunostained, microphotographed and counted using image analysis software. Statistical analyses were carried out to establish significant differences of neuronal and glial populations among the selected segments, between the glial cells in a segment, and glial cells in white and gray matter. Results show that glia to neuron ratio in the posterior gray matter of the human spinal cord within the T8-T11 vertebral region is in the range 11 : 1 to 13 : 1, although not significantly different among vertebral segments. Glia cells are more abundant in gray matter than in white matter, whereas astrocytes and oligodendrocytes are more abundant than microglia (40 : 40 : 20). Interestingly, the population of oligodendrocytes in the T9/T10 intersection is significantly larger than in any other segment. In conclusion, glial cells are the predominant bodies in the posterior gray and white matter of the T8-T11 segments of the human spinal cord. Given the crucial role of glial cells in the development and maintenance of neuropathic pain, and their electrophysiological characteristics, anatomical determination of the ratio of different cell populations in spinal segments commonly exposed to SCS is fundamental to understand fully the biological effects observed with this therapy.
Learn More >Persistent opioid use is common after surgical procedures, and postoperative opioid prescribing often transitions from surgeons to primary care physicians in the months after surgery. It is unknown how surgeons currently transition these patients or the preferred approach to successful coordination of care. This qualitative study aimed to describe transitions of care for postoperative opioid prescribing and identify barriers and facilitators of ideal transitions for potential intervention targets.
Learn More >Previous studies reported that long-term nociceptive stimulation could result in neurovascular coupling (NVC) dysfunction in brain, but these studies were based mainly on unimodal imaging biomarkers, thus could not comprehensively reflect NVC dysfunction. We investigated the potential NVC dysfunction in chronic migraine by exploring the relationship between neuronal activity and cerebral perfusion maps. The Pearson correlation coefficients between these 2 maps were defined as the NVC biomarkers. NVC biomarkers in migraineurs were significantly lower in left inferior parietal gyrus (IPG), left superior marginal gyrus (SMG) and left angular gyrus (AG), but significantly higher in right superior occipital gyrus (SOG), right superior parietal gyrus (SPG), and precuneus. These brain regions were located mainly in parietal or occipital lobes and were related to visual or sensory information processing. ALFF-CBF in right SPG was positively correlated with disease history and that in right precuneus was negatively correlated with migraine persisting time. fALFF-CBF in left SMG was negatively related to headache frequency and positively related to health condition. fALFF-CBF in left AG was negatively related to headache frequency and positively related to disease history and health condition. In conclusion, multi-modal MRI could be used to detect NVC dysfunction in chronic migraine patients, which is a new method to assess the impact of chronic pain to the brain.
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