Pain
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Hyperalgesia is a cardinal symptom of opioid withdrawal. The transient receptor potential vanilloid 1 (TRPV1) is a ligand-gated ion channel expressed on sensory neurons responding to noxious heat, protons, and chemical stimuli such as capsaicin. TRPV1 can be inhibited via μ-opioid receptor (MOR)-mediated reduced activity of adenylyl cyclases (ACs) and decreased cyclic adenosine monophosphate (cAMP) levels. ⋯ Inhibition of AC and PKA, as well as mutations of the PKA phosphorylation sites threonine 144 and serine 774, prevented the enhanced TRPV1 activity. Finally, capsaicin-induced nocifensive behavior was increased during opioid withdrawal in vivo. In summary, our results demonstrate an increased activity of TRPV1 in DRG neurons as a new mechanism contributing to opioid withdrawal-induced hyperalgesia.
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Modern forms of music therapy are clinically established for various therapeutic or rehabilitative goals, especially in the treatment of chronic pain. However, little is known about the neuronal mechanisms that underlie pain modulation by music. Therefore, we attempted to characterize the effects of music therapy on pain perception by comparing the effects of 2 different therapeutic concepts, referred to as receptive and entrainment methods, on cortical activity recorded by magnetencephalography in combination with laser heat pain. ⋯ On the other hand, listening to self-composed "pain music" and "healing music" within the entrainment method exerted major effects on gamma-band activity in primary and secondary somatosensory cortices. Pain music, in contrast to healing music, increased pain ratings in parallel with an increase in gamma-band activity in somatosensory brain structures. In conclusion, our data suggest that the 2 music therapy approaches operationalized in this study seem to modulate pain perception through at least 2 different mechanisms, involving changes of activity in the delta and gamma bands at different stages of the pain processing system.
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Facial expressions provide a primary source of inference about a child's pain. Although facial expressions typically appear spontaneous, children have some capacity to fake or suppress displays of pain, thereby potentially misleading caregiver judgments. The present study was designed to compare accuracy of different groups of caregivers in detecting deception in children's facial expressions of pain when voluntarily controlled. ⋯ A 3 (group: pediatrician vs pediatric nurse vs parent)×4 (condition: genuine vs faked vs suppressed vs neutral) mixed analysis of variance (ANOVA) of judgment accuracies revealed a significant main effect of group, with nurses demonstrating higher overall accuracy scores than parents, and pediatricians not differing from either group. As well, all caregivers, regardless of group, demonstrated the lowest accuracy when viewing the genuine condition, relative to the faked and suppressed conditions, with accuracy for the neutral condition not differing significantly from the other conditions. Overall, caregivers were more successful at identifying faked and suppressed than genuine expressions of pain in children, and pediatric nurses fared better overall in judgment accuracy than parents.
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Case Reports
Trigeminal neuralgia secondary to giant Virchow-Robin spaces: a case report with neuroimaging.
Virchow-Robin spaces are pial-lined, interstitial, fluid-filled structures that accompany penetrating arteries and arterioles as they enter the cerebral substance. Occasionally they may enlarge and become giant Virchow-Robin spaces (GVRS) and produce mass effect. ⋯ Routine 1.5 T MRI sequences were sufficient to diagnose the GVRS and a diffusion tensor imaging (DTI) study revealed distortion of the intrinsic trigeminal pathway. This study highlights the utility of routine MRI to study the intrinsic anatomy of the trigeminal pathway in pathological conditions.