Pain
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Co-existing algogenic conditions in two internal organs in the same patient may mutually enhance pain symptoms (viscero-visceral hyperalgesia). The present study assessed this phenomenon in different models of visceral interaction. ⋯ In patients' subgroups, symptoms were also re-assessed after treatment of each condition or after no treatment. (a) CAD+Gs presented more numerous/intense angina/biliary episodes and more referred muscle chest/abdominal hyperalgesia than CAD or Gs; cardiac revascularization or cholecystectomy also reduced biliary or cardiac symptoms, respectively (0.001
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The conscious perception of somatosensory stimuli is thought to be located in the contralateral cerebral cortex. However, recent human brain imaging investigations in the spinal system report bilateral primary somatosensory cortex (SI) activations during unilateral noxious stimuli and that this ipsilateral spinal representation may be independent of transcallosal connections. In the trigeminal system, there is primate evidence for an ipsilateral somatosensory pathway through the thalamus to the face SI. ⋯ We found that both muscle and cutaneous noxious stimuli, from injections of hypertonic saline into the right masseter or overlying skin, evoked bilateral increases in signal intensity in the region encompassing the ventral posterior thalamus as well as the face region of SI and SII. In contrast, innocuous unilateral brushing of the lower lip evoked a strict contralateral ventroposterior thalamic activation, but bilateral activation of SI and SII. These data indicate that, in contrast to innocuous inputs from the face, noxious information ascends bilaterally to the face SI through the ventroposterior thalamus in humans.
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Brief noxious heat evokes more intense pain in women than in men; however, sex differences in the intensity of pain sensations evoked in hairy and glabrous skins are not clearly understood. Glabrous skin putatively lacks the type of A-delta nociceptors that underlie heat-evoked sharp sensation. Therefore, we assessed whether noxious heat-evoked pain qualities differed for hairy and glabrous skins and whether sex differences exist in these evoked pains. ⋯ Sharp, stinging and cutting sensations were evoked in glabrous skin, but the magnitude of these sensations was greater in hairy skin than glabrous skin; an effect only in females. Also, there was no sex difference in sharp sensation and annoyance in glabrous skin. These findings suggest that sharp sensations are evoked more prominently in hairy than in glabrous skin of women and that sharp sensations and annoyance play a prominent role in mediating aspects of pain-evoked from hairy skin in women.
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Chronic itch is a symptom of many skin conditions and systemic disease, and it has been hypothesized that the chronic itch may result from sensitization of itch-signaling pathways. We induced experimental chronic dry skin on the rostral back of mice, and observed a significant increase in spontaneous hindlimb scratches directed to the dry skin. Spontaneous scratching was significantly attenuated by a PAR-2 antibody and 5-HT2A receptor antagonist, indicating activation of these receptors by endogenous mediators released under dry skin conditions. ⋯ DRG cells from dry skin mice exhibited significantly larger responses to the PAR-2 agonist and 5-HT, but not histamine. Spontaneous scratching may reflect ongoing itch, and enhanced pruritogen-evoked scratching may represent hyperknesis (enhanced itch), both potentially due to sensitization of itch-signaling neurons. The correspondence between enhanced behavioral scratching and DRG cell responses suggest that peripheral pruriceptors that respond to proteases and 5-HT, but not histamine, may be sensitized in dry skin itch.