Pain
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Randomized Controlled Trial
Non-invasive vagus nerve stimulation modulates trigeminal but not somatosensory perception: functional evidence for a trigemino-vagal system in humans.
Noninvasive vagus nerve stimulation (nVNS) is effective in several types of headache disorders. We sought to unravel the mechanism of how nVNS exhibits this efficacy. This study used a randomized, single-blind, sham-controlled, crossover design and comprised 3 projects with 3 independent cohorts of healthy participants. ⋯ Heart rate variability parameters did not change after nVNS. Our results provide functional evidence of a long hypothesized functional trigemino-vagal system in humans and may explain why nVNS is effective in some headache disorders but not in somatic pain disorders. Because unilateral nVNS modulated the trigeminal thresholds bilaterally, this effect is probably indirect through a central top-down mechanism.
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We assessed the joint effects of back pain and mental health conditions on healthcare utilization and costs in a population-based sample of adults in Ontario. We included Ontario adult respondents of the Canadian Community Health Survey between 2003 and 2012, followed up to 2018 by linking survey data to administrative databases. Joint exposures were self-reported back pain and mental health conditions (fair/poor mental health, mood, and anxiety disorder). ⋯ There was no evidence of synergism for all-cause utilization or costs. Combined effects of back pain and mental health conditions on back pain-specific utilization or opioid prescription were greater than expected, with evidence of synergism. Health services targeting back pain and mental health conditions together may provide greater improvements in outcomes.
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Individually unique dynamics of cortical connectivity reflect the ongoing intensity of chronic pain.
Chronic pain diseases are characterised by an ongoing and fluctuating endogenous pain, yet it remains to be elucidated how this is reflected by the dynamics of ongoing functional cortical connections. In this study, we investigated the cortical encoding of 20 patients with chronic back pain and 20 chronic migraineurs in 4 repeated fMRI sessions. A brain parcellation approach subdivided the whole brain into 408 regions. ⋯ Of interest, the group results were not mirrored by the individual patterns of pain-related connectivity, which rejects the idea of a common neuronal core problem for chronic pain diseases. The diversity of the individual cortical signatures of chronic pain encoding results adds to the understanding of chronic pain as a complex and multifaceted disease. The present findings support recent developments for more personalised medicine.
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Resistance training-based exercise is commonly prescribed in the clinic for the treatment of chronic pain. Mechanisms of aerobic exercise for analgesia are frequently studied, while little is known regarding resistance training mechanisms. We developed a resistance training model in mice and hypothesized resistance training would protect against development of muscle pain, mediated through the activation of androgen receptors. ⋯ However, single administration of flutamide (1, 3, 10 mg/kg) in resistance-trained animals had no effect on existing exercise-induced protection against muscle pain. Therefore, resistance training acutely increases lactate and testosterone and strength overtime. Eight weeks of resistance training prevents the development of hyperalgesia through the activation of androgen receptors in an animal model of muscle pain.
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Pediatric functional abdominal pain disorders (FAPD) are highly prevalent, difficult to diagnose, and challenging to treat. The brain systems supporting FAPD remain poorly understood. This investigation examined the neuromechanisms of FAPD during a well-tolerated visceral pain induction task, the water load symptom provocation task (WL-SPT). ⋯ Amygdala FC with the DMN in youth with FAPD also differed from healthy controls. Global cerebral blood flow changes were also noted between FAPD and healthy controls, but no significant differences in grey matter were detected either between groups or during the WL-SPT in youth with FAPD. Findings confirm youth with FAPD undergo changes in brain systems that could support the development of biomarkers to enhance understanding of the mechanisms of pain and treatment response.