Pain
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Randomized Controlled Trial
Amygdala activity contributes to the dissociative effect of cannabis on pain perception.
Cannabis is reported to be remarkably effective for the relief of otherwise intractable pain. However, the bases for pain relief afforded by this psychotropic agent are debatable. Nonetheless, the frontal-limbic distribution of cannabinoid receptors in the brain suggests that cannabis may target preferentially the affective qualities of pain. ⋯ Critically, the reduction in sensory-limbic functional connectivity was positively correlated with the difference in drug effects on the unpleasantness and the intensity of ongoing pain. Peripheral mechanisms alone cannot account for the dissociative effects of THC on the pain that was observed. Instead, the data reveal that amygdala activity contributes to interindividual response to cannabinoid analgesia, and suggest that dissociative effects of THC in the brain are relevant to pain relief in humans.
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Drug-resistant chronic cluster headache (CH) is an unremitting illness with excruciatingly severe headaches that occur several times daily. Starting in 2000, a total of 19 patients with long-lasting chronic CH, with multiple daily attacks unresponsive to all known prophylactics, received stimulation of the posterior inferior hypothalamic area ipsilateral to the pain as treatment. We report long-term follow-up (median 8.7 years, range 6-12 years) in 17 patients. ⋯ This exceptionally long follow-up shows that hypothalamic stimulation for intractable chronic CH produces long-lasting improvement in many patients. Previous experience was limited to a median of 16 months. Important new findings are as follows: stimulation is well tolerated for many years after implantation; after several years during which stimulation was necessary for relief, a persistent almost pain-free condition can be maintained when stimulation is off, suggesting that hypothalamic stimulation can change disease course; tolerance can occur after marked long-lasting improvement; and bilateral chronic CH seems to predict poor response to hypothalamic stimulation.
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Neuroimaging studies have suggested the presence of alterations in the anatomo-functional properties of the brain of patients with chronic pain. However, investigation of the brain circuitry supporting the perception of clinical pain presents significant challenges, particularly when using traditional neuroimaging approaches. While potential neuroimaging markers for clinical pain have included resting brain connectivity, these cross-sectional studies have not examined sensitivity to within-subject exacerbation of pain. ⋯ Maneuvers also disrupted the DMN-pgACC connectivity, which at baseline was anticorrelated with pain. Finally, baseline DMN connectivity predicted maneuver-induced changes in both pain and DMN-rINS connectivity. Our results support the use of arterial spin labeling to evaluate clinical pain, and the use of resting DMN connectivity as a potential neuroimaging biomarker for chronic pain perception.
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Both neuroticism, a higher-order, stable personality trait, and anxiety sensitivity (AS), a lower-order pain-related construct, have been associated with pain, although no research exists examining the relationship of both these constructs to acute pain in children. In the current study, 99 healthy children (53 girls) completed self-report measures of neuroticism and AS before undergoing pain tasks involving cold and pressure pain. ⋯ Mediational models revealed that AS partially mediated relationships between neuroticism and pain intensity/bother, and fully mediated relationships between neuroticism and anticipatory anxiety. These data suggest that, at least in children, neuroticism may be best understood as a vulnerability factor for elevated pain responses, especially when coupled with a fear of bodily sensations.