Pain
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We have recently shown that subjects can learn to use cognitive-emotional strategies to suppress their spinal nociceptive flexor reflex (RIII reflex) under visual RIII feedback and proposed that this reflects learned activation of descending pain inhibition. Here, we investigated whether learned RIII suppression also affects supraspinal nociception and whether previous relaxation training increases success. Subjects were trained over 3 sessions to reduce their RIII size by self-selected cognitive-emotional strategies. ⋯ The present results show that learned RIII suppression also affects supraspinal nociception as quantified by SEPs, although effects on pain ratings were less clear. Lower motor neuron excitability as quantified by F-waves was not affected. Previous relaxation training did not significantly improve RIII feedback training success.
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Previous studies have reported that 15% to 25% of patients treated for breast cancer experience long-term moderate-to-severe pain in the area of surgery, potentially lasting for several years. Few prospective studies have included all potential risk factors for the development of persistent pain after breast cancer surgery (PPBCS). The aim of this prospective cohort study was to comprehensively identify factors predicting PPBCS. ⋯ Higher preoperative diastolic blood pressure was associated with reduced risk of PPBCS (OR: 0.98 per mm Hg, P = 0.01). Both patient- and treatment-related risk factors predicted PPBCS. Identifying patients at risk may facilitate targeted intervention.
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Offset analgesia (OA) is a form of endogenous pain inhibition characterized by a disproportionately large reduction in pain perception after a small decrease in temperature during noxious thermal stimulation. In this study, the presence of OA was evaluated in patients with fibromyalgia and compared with healthy age-matched and sex-matched controls. Offset analgesia was induced by noxious thermal stimulation on the arm, causing a visual analog score (VAS) of about 50 mm, followed by a 1°C temperature decrease. ⋯ Decreased OA responses were not enhanced or restored by repeating the OA paradigm or by the downward step test. Defective engagement of OA had a significant effect on pain onset, as observed from the upward OA step test, with less tolerability to noxious pain stimulation in patients with fibromyalgia. In conclusion, patients with fibromyalgia showed less pain inhibition as measured by the OA paradigm, which influenced both the onset and offset of pain.