Pain
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Editorial Comment
Mechanism-based therapy of neuropathic pain - a concept in danger?
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Randomized Controlled Trial
Acupuncture induced changes of the pressure pain threshold are mediated by segmental inhibition - a randomized controlled trial.
Our aim was to distinguish between spinal and supraspinal mechanisms in the intact nervous system by comparing homosegmental and heterosegmental effects of electroacupuncture (EA) and manual acupuncture (MA) on sensory perception in healthy volunteers by means of quantitative sensory testing. Seventy-two healthy volunteers were randomly assigned to receive either MA or EA at SP 6, SP 9, GB 39, and ST 36 at the left leg or relaxed for 30 minutes (control group [CG]). Blinded examiners assessed 13 sensory modalities (thermal and mechanical detection and pain thresholds) at the upper arms and lower legs before and after intervention by means of a standardized quantitative sensory testing battery. ⋯ The PPT can be changed by EA. The PPT increase was confined to the segment of needling, which indicates that it is mainly mediated by segmental inhibition in the spinal cord. This underscores the importance of segmental needling and electrical stimulation in clinical practice.
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Previous studies have shown that the outcomes of complex regional pain syndrome (CRPS) vary significantly between patients, but few studies have identified prognostic indicators. The aim of this study was to determine whether psychological factors are associated with recovery from recently onset CRPS amongst patients followed prospectively for 1 year. Sixty-six patients with CRPS (type 1) were recruited within 12 weeks of symptom onset and assessed immediately and at 6 and 12 months, during which time they received treatment as usual. ⋯ Those with lower baseline anxiety and disability had the lowest pain intensity over the study period, and those with lower baseline pain and pain-related fear experienced the least disability over the 12 months. This suggests that anxiety, pain-related fear, and disability are associated with poorer outcomes in CRPS and could be considered as target variables for early treatment. The findings support the theory that CRPS represents an aberrant protective response to perceived threat of tissue injury.
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Hypersensitivity of pain pathways is considered a relevant determinant of symptoms in chronic pain patients, but data on its prevalence are very limited. To our knowledge, no data on the prevalence of spinal nociceptive hypersensitivity are available. We studied the prevalence of pain hypersensitivity and spinal nociceptive hypersensitivity in 961 consecutive patients with various chronic pain conditions. ⋯ To our knowledge, this is the largest prevalence study on central hypersensitivity and the first one on the prevalence of spinal nociceptive hypersensitivity in chronic pain patients. The results revealed an impressively high prevalence, supporting a high clinical relevance of this phenomenon. Electrical pain thresholds and nociceptive withdrawal reflex explore aspects of pain processing that are mostly independent of sociodemographic, psychological, and clinical pain-related characteristics.
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An increased cardiovascular event rate in elderly patients under opioid medications was recently reported. One reason for this increase could be the occurrence of nocturnal apnea and hypoxia, as a consequence of sleep-disordered breathing (SDB). Using a controlled study, we prospectively analyzed SDB using polysomnography in a total of 18 patients before and after opioid withdrawal (opioid withdrawal group [OG]) and 14 patients before and after comprehensive pain management (without any strong-acting opioids) who served as the control group (CG). ⋯ The AHI was not significantly affected by body mass index, age, or sex. Obviously, nocturnal apnea and O2 desaturation occurred more frequently, as was clinically expected in patients with opioid intake; these findings may explain the opioid-associated cardiovascular morbidity. Thus, SDB may be a risk at lower opioid doses than hitherto described, and particular caution should be exercised in patients with comorbidities that might make them vulnerable to the consequences of SDB.