European journal of pain : EJP
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Diffusion Tensor Imaging (DTI) is a promising new imaging method allowing in vivo mapping of anatomical connections in the living human brain. We combined DTI with functional magnetic resonance imaging (fMRI) to investigate the anatomical relationships between areas involved in visceral sensations in humans. Non-painful and moderately painful rectal distensions were performed in 11 healthy women (38.4+/-3.1years). fMRI was used to analyse the changes in brain activity during both types of distension. ⋯ DTI revealed direct connections between insula, and the four areas more frequently activated in this study, i.e. ACC, thalamus, S1, S2 and PFC. The combined use of fMRI and DTI in healthy subjects during rectal distension revealed a neural network of visceral sensory perception involving the insula, thalamus, somatosensory cortices, ACC and PFC.
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Most forms of visceral pain generate intense referred hyperalgesia but the mechanisms of this enhanced visceral hypersensitivity are not known. The on-cells of the rostral ventromedial medulla (RVM) play an important role in descending nociceptive facilitation and can be sensitized to somatic mechanical stimulation following peripheral nerve injury or hindpaw inflammation. Here we have tested the hypothesis that visceral noxious stimulation sensitizes RVM ON-like cells, thus promoting an enhanced descending facilitation that can lead to referred visceral hyperalgesia. ⋯ Moreover, ON-like cells acquired a novel response to CRD and responded to heat stimulation in the innocuous range. OFF-like neurons responded to capsaicin administration with a brief (<5 min) inhibition of activity followed by an enhanced inhibition to noxious stimulation and a novel inhibition to innocuous stimulation (CRD and heat) at early time points (10 min post capsaicin). These results support the hypothesis that noxious visceral stimulation may cause referred hypersensitivity by promoting long-lasting sensitization of RVM ON-like cells.
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Living with chronic pain may be a threatening experience to one's own gender identity. Findings suggest that the presence of chronic pain does not allow individuals to achieve the most valued standards of being male or female in our societies. Such contention, however, has not yet been empirically supported. ⋯ Results have generally supported our hypotheses. Both laypeople and nurses perceived: (1) the man with CLBP as having less masculinity and more femininity-related traits than the typical man; (2) the woman with CLBP as having less femininity and more masculinity-related traits than the typical woman; and (3) the man and woman with CLBP as more similar to each other than the typical man/woman. Issues on gender identity conflicts in CP patients are discussed.
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Despite advances in postoperative pain management, the proportion of patients with moderate to severe postoperative pain is still ranging 20-80%. In this retrospective study, we investigated 1736 patients to determine the incidence of postoperative pain in need of intervention (PPINI)defined as numeric rating scale >4 at rest in the post anaesthesia care unit early after awakening from general anaesthesia, and to identify possible risk factors. The proportion of patients with PPINI was 28.5%. ⋯ Patients with PPINI experienced significantly more PONV (10.3% vs. 6.2%, p=0.003), more psychomotor agitation (5.5% vs. 2.7%, p=0.004), needed more application of opioid in PACU (62.8% vs. 24.2%, p<0.001), stayed significantly longer in PACU (89.6min [70-120] vs. 80min [60-100], p<0.001), had a longer median length of hospital stay (6.6 days [4.0-8.8] vs. 6.0 days [3.2-7.8]], p<0.001), and longer postoperative stay (5.0 days [3.0-6.5] vs. 4.1 days [2.5-5.8], p<0.001]). Patients with PPINI required more piritramid (8.0mg [5.0-12.0] vs. 5.0mg [3.0-7.8], p<0.001) in PACU than patients without. The identification of patients at high risk for immediate postoperative pain in need of intervention would enable the formation of effective postoperative pain management programs.
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Assessments of spinal nociceptive withdrawal reflexes can be used in human research both to evaluate the effect of analgesics and explore pain mechanisms related to sensitization. Before the reflex can be used as a clinical tool, normative values need to be determined in large scale studies. The aim of this study was to determine the reference values of spinal nociceptive reflexes and subjective pain thresholds (to single and repeated stimulation), and of the area of the reflex receptive fields (RRF) in 300 pain-free volunteers. ⋯ In conclusion, normative values of parameters related to the spinal nociceptive reflex were determined. This allows their clinical application for assessing central hyperexcitability in individual patients. The parameters investigated explore different aspects of sensitization processes that are largely independent of demographic characteristics, cognitive and affective factors.