The journal of pain : official journal of the American Pain Society
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Emotion has a strong modulatory effect on pain perception and spinal nociception. Pleasure inhibits pain and nociception, whereas displeasure facilitates pain and nociception. Dysregulation of this system has been implicated in development and maintenance of chronic pain. ⋯ Moreover, the results suggest a physiological basis for a previously identified phenotype associated with risk for chronic pain and thus a potentially new target for chronic pain prevention efforts. PERSPECTIVE: This study demonstrated that reduction of dorsolateral prefrontal cortical excitability by transcranial direct current stimulation attenuates the impact of emotional image viewing on nociceptive reflex activity during painful electrocutaneous stimulation. This result confirms there is cortical involvement in emotional modulation of spinal nociception and opens avenues for future clinical research.
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C-tactile (CT) fibers, responsible for the so-called "affective" touch (AT), have drawn a fair amount of attention within the scientific community for their marked social dimension. However, while the pain-relieving potential of discriminative touch (DT) has been documented, proofs of the analgesic properties of AT are still scarce. Additionally, no study has so far tested its possible pain-relieving effects on a clinically-relevant model. ⋯ Targeting CT fibers could pave the way to new treatments for chronic pain conditions whose aetiology depend on abnormal C-nociceptors' physiology. PERSPECTIVE: This study extends previous findings on the analgesic potential of affective touch, documenting a clear pain reduction during temporal summation of second pain (TSSP). Since TSSP is thought to reflect central sensitization, the psychophysiological mechanisms of affective touch could be exploited for new chronic pain treatments.
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Chronic low back pain (cLBP) has been associated with changes in brain plasticity. Nonpharmacological therapies such as Manual Therapy (MT) have shown promise for relieving cLBP. However, translational neuroimaging research is needed to understand potential central mechanisms supporting MT. ⋯ Furthermore, this reduction post-manipulation occurs via modulation of SLN connectivity to sensorimotor, affective, and cognitive processing regions. PERSPECTIVE: MT both reduces clinical low back pain and modulates brain activity important for the processing of pain. This modulation was shown by increased functional brain connectivity between the salience network and brain regions involved in cognitive, affective, and sensorimotor processing of pain.
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Fibromyalgia syndrome (FMS) is a chronic widespread pain condition of unknown aetiology. The role of temperature in FMS pain has not been reviewed systematically. The goal of this study was to review the influences of temperature on pain in FMS, from meteorological and quantitative sensory testing (QST) studies. ⋯ Additional work is required to elucidate the factors that determine why a subgroup of patients perceive low ambient temperatures as painful, and to characterize that group. PERSPECTIVE: Patients often report increased pain with changes in ambient temperature; even disabling, extreme temperature sensitivity in winter. Understanding this phenomenon may help clinicians provide reassurance and advice to patients and may guide research into the everyday impact of such hypersensitivity, whilst directing future work into the pathophysiology of FMS.
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Threat-induced pain modulation can increase survival by amplifying physiological and behavioral reactions toward danger. Threat can also modulate spinal nociception, suggesting engagement of endogenous top-down circuitry. A unique method to assess spinal nociception is via reflex receptive fields (RRF) associated with the nociceptive withdrawal reflex (NWR, a protective spinally-mediated reflex). ⋯ This is likely mediated by top-down circuitry that enhances dorsal horn nociceptive neurons by enlarging RRFs and amplifying ascending pain signals. PERSPECTIVE: This article presents the enlargement of RRF during periods of threat. The results from this study may help clarify the mechanism underlining emotional modulation of spinal nociception.