Pain
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The aim of this study was to investigate the role of local acidosis in the generation of pain in complex regional pain syndrome (CRPS). We investigated ten patients with CRPS of the upper extremity with a mean duration of the disease of 43 weeks (range 4-280 weeks) and ten control subjects for sensitivity to infusion of fluids with low pH (pH 6.1). Another group of five CRPS patients and three healthy controls was investigated using the same protocol but neutral infusion fluid (pH 7.4). ⋯ Neutral SIF evoked no pain at all, neither in CRPS patients (ipsi 0 AUC, contra 0 AUC) nor in healthy controls. Our results suggest that hyperalgesia to protons is present in patients with CRPS. Further, we could demonstrate that pain is not only restricted to the skin but is also generated in deep somatic tissue of the affected limb.
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Alterations in activation of pain modulation systems may play a role in the pathophysiology of irritable bowel syndrome (IBS). However, little is known about the effects of exogenous opioids on the perceptual and autonomic responses to aversive visceral stimulation. The aim of the study was to evaluate the effect of the mu opioid-preferring analgesic fentanyl (FEN), given intravenously, on perceptual and autonomic responses to rectal distension. ⋯ FEN had no effect on rectal tone or compliance. FEN dose-dependently attenuates the perception of phasic rectal distension and affects unpleasantness ratings during random fixed rectal distension, with a greater relative efficacy for this antinociceptive effect in IBS patients. These findings support the hypothesis that IBS patients may have an altered central release of endogenous opioids in response to visceral stimulation.
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Peripheral neuropathic pain is produced by multiple etiological factors that initiate a number of diverse mechanisms operating at different sites and at different times and expressed both within, and across different disease states. Unraveling the mechanisms involved requires laboratory animal models that replicate as far as possible, the different pathophysiological changes present in patients. It is unlikely that a single animal model will include the full range of neuropathic pain mechanisms. ⋯ The mechanical (von Frey and pinprick) sensitivity and thermal (hot and cold) responsiveness is increased in the ipsilateral sural and to a lesser extent saphenous territories, without any change in heat thermal thresholds. Crush injury of the tibial and common peroneal nerves produce similar early changes, which return, however to baseline at 7-9 weeks. The spared nerve injury model may provide, therefore, an additional resource for unraveling the mechanisms responsible for the production of neuropathic pain.
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Little is known about the epidemiology of pain in children. We studied the prevalence of pain in Dutch children aged from 0 to 18 years in the open population, and the relationship with age, gender and pain parameters. A random sample of 1300 children aged 0-3 years was taken from the register of population in Rotterdam, The Netherlands. ⋯ The intensity of pain was higher in the case of chronic pain (P<0. 001) and multiple pains (P<0.001), and for chronic pain the intensity was higher for girls (P<0.001). These findings indicate that chronic pain is a common complaint in childhood and adolescence. In particular, the high prevalence of severe chronic pain and multiple pain in girls aged 12 years and over calls for follow-up investigations documenting the various bio-psycho-social factors related to this pain.
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Phantom pain in subjects with an amputated limb is a well-known problem. However, estimates of the prevalence of phantom pain differ considerably in the literature. Various factors associated with phantom pain have been described including pain before the amputation, gender, dominance, and time elapsed since the amputation. ⋯ Phantom pain is a common problem in upper limb amputees that causes considerable suffering for the subjects involved. Only a minority of subjects are treated for phantom pain. Further research is needed to determine factors associated with phantom pain.