Pain
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Randomized Controlled Trial
High altitude headache: the effects of real versus sham oxygen administration.
High-altitude, or hypobaric hypoxia, headache has recently emerged as an interesting model to study placebo and nocebo responses, and particularly their peripheral mechanisms. In this study, we analyze the response of this type of headache to either real or sham (placebo) oxygen (O(2)) administration at an altitude of 3500 m, where blood oxygen saturation (SO(2)) drops from the normal value of about 98% to about 85%. In a trial in which a double-blind administration of either 100% O(2) or sham O(2) was administered, we tested pre- and post-exercise headache, along with fatigue, heart rate (HR) responses, and prostaglandin E(2) (PGE(2)) salivary concentration. ⋯ First, placebo O(2) is effective in reducing post-exercise headache, along with HR and PGE(2) decrease, only after O(2) preconditioning. Second, pre-exercise (at rest) headache is not affected by placebo O(2), which emphasizes the limits of a placebo treatment at high altitude. Third, fatigue is affected by placebo O(2) even without prior O(2) conditioning, which suggests the higher placebo sensitivity of fatigue compared with headache pain at high altitude.
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Opioids are important in the management of pain in patients with cancer. Clinicians and patients are sometimes concerned about the effect of opioids on survival, which might decrease opioid prescription, compliance, and symptom control. We wanted to determine whether opioid analgesia was associated with shorter survival in adult patients with cancer. ⋯ In view of this, no definitive conclusions can be made as to whether opioids affect survival in patients with cancer. These data suggest that while opioid analgesia does not affect survival at the end of life, in the context of longer-term treatment, higher-quality studies, with survival as a primary endpoint, are needed to confirm an independent association between opioid analgesia and shorter survival. An important limitation of research in this field is that the relationship between greater analgesic requirements and shorter survival may be mediated by painful progressive cancer.
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Self-compassion is the ability to respond to one's failures, shortcomings, and difficulties with kindness and openness rather than criticism. This study, which might be regarded as a proof-of-concept study, aimed to establish whether self-compassion is associated with expected emotional responses and the likelihood of responding with problem solving, support seeking, distraction, avoidance, rumination, or catastrophizing to unpleasant self-relevant events occurring in 3 social contexts. Sixty chronic pain patients were presented with 6 vignettes describing scenes in which the principal actor transgressed a social contract with negative interpersonal consequences. ⋯ Work-related vignettes were rated as more emotional and more likely to be associated with avoidance, catastrophizing, and rumination and less likelihood of problem solving. The findings suggest that self-compassion warrants further investigation in the chronic pain population both regarding the extent of its influence as a trait and in terms of the potential to enhance chronic pain patients' ability to be self-compassionate, with a view to its therapeutic utility in enhancing psychological well-being and adjustment. Limitations regarding the possible criterion contamination and the generalizability of vignette studies are discussed.
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The experience of pain in humans is modulated by endogenous opioids, but it is largely unknown how the opioid system adapts to chronic pain states. Animal models of chronic pain point to upregulation of opioid receptors (OpR) in the brain, with unknown functional significance. We sought evidence for a similar relationship between chronic pain and OpR availability in humans. ⋯ These findings are consistent with the view that chronic pain may upregulate OpR availability to dampen pain. Finally, patients with arthritis pain, compared with healthy controls, had overall less OpR availability within the striatum specifically, consistent with the greater endogenous opioid binding that would be expected in chronic pain states. Our observational evidence points to the need for further studies to establish the causal relationship between chronic pain states and OpR adaptation.
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Surgical nerve injury sometimes leads to chronic postsurgical neuropathic pain (CPSNP). The risk factors for this condition are not well understood. We prospectively assessed 46 patients scheduled for iliac crest bone harvest, 2 days (D2) and 3 months (M3) after surgery, to determine the time course of nerve fiber degeneration and expression of the TNF-α and NGF genes in skin punch biopsies. ⋯ However, in patients with CPSNP, burning, compression, and pain provoked by brushing were correlated with IENFD at M3, suggesting a possible association between partial nerve lesions and more intense CPSNP, than with total nerve lesion. Furthermore, preoperative pain and opioid use were higher in patients who developed CPSNP than in those without CPSNP. These findings suggest that the predictors of CPSNP development are clinical rather than histological or biochemical.