Pain
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Randomized Controlled Trial Multicenter Study
Dorsal root ganglion stimulation yielded higher treatment success rate for CRPS and causalgia at 3 and 12 months: randomized comparative trial.
Animal and human studies indicate that electrical stimulation of dorsal root ganglion (DRG) neurons may modulate neuropathic pain signals. ACCURATE, a pivotal, prospective, multicenter, randomized comparative effectiveness trial, was conducted in 152 subjects diagnosed with complex regional pain syndrome or causalgia in the lower extremities. Subjects received neurostimulation of the DRG or dorsal column (spinal cord stimulation, SCS). ⋯ Dorsal root ganglion stimulation also demonstrated greater improvements in quality of life and psychological disposition. Finally, subjects using DRG stimulation reported less postural variation in paresthesia (P < 0.001) and reduced extraneous stimulation in nonpainful areas (P = 0.014), indicating DRG stimulation provided more targeted therapy to painful parts of the lower extremities. As the largest prospective, randomized comparative effectiveness trial to date, the results show that DRG stimulation provided a higher rate of treatment success with less postural variation in paresthesia intensity compared to SCS.
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The expression pattern of important transduction molecules in nociceptive sensory neurons is likely to dictate pain sensitivity. While this notion is well established for increased pain sensitivities under conditions like inflammation and neuropathy, less is known as to which molecules are defining interindividual differences in pain sensitivity in healthy subjects. A genome-wide methylation analysis on monozygotic twins found that methylation of a CpG dinucleotide in the promoter of transient receptor potential ankyrin 1 (TRPA1) is inversely associated with the threshold for heat-induced pain. ⋯ Using DNA from whole-blood samples of 75 healthy volunteers, we found that the same CpG site previously found to affect the threshold for heat-evoked pain is hypermethylated in subjects with a low threshold for pressure pain. We also found gender differences, with females displaying higher methylation rates combined with higher pressure pain sensitivities as compared with males. In conclusion, our findings support the notion that epigenetic regulation of TRPA1 seems to regulate thermal and mechanical pain sensitivities.
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The left and right central amygdalae (CeA) are limbic regions involved in somatic and visceral pain processing. These 2 nuclei are asymmetrically involved in somatic pain modulation; pain-like responses on both sides of the body are preferentially driven by the right CeA, and in a reciprocal fashion, nociceptive somatic stimuli on both sides of the body predominantly alter molecular and physiological activities in the right CeA. Unknown, however, is whether this lateralization also exists in visceral pain processing and furthermore what function the left CeA has in modulating nociceptive information. ⋯ Finally, divergent left and right CeA functions were evaluated during abdominal mechanosensory testing. In naive animals, channelrhodopsin-2-mediated activation of the right CeA induced mechanical allodynia, and after cyclophosphamide-induced bladder sensitization, activation of the left CeA reversed referred bladder pain-like behaviors. Overall, these data provide evidence for functional brain lateralization in the absence of peripheral anatomical asymmetries.