Pain
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Randomized Controlled Trial Clinical Trial
Pain relief with lidocaine 5% patch in localized peripheral neuropathic pain in relation to pain phenotype.
In neuropathic pain with irritable nociceptor (IN) phenotype, upregulation of sodium channels on nociceptors is supposed to be an important pain mechanism that may be targeted by topical sodium channel blockade. This randomised, double-blind, phenotype panel, crossover study with 4-week treatment periods of lidocaine 5% patch and placebo was performed to search for phenotype differences in effect. The primary efficacy measure was the total pain intensity on an 11-point numeric rating scale, and the primary objective was to compare the effect of lidocaine in patients with and without IN phenotype as defined by hypersensitivity and preserved small-fibre function determined by quantitative sensory testing. ⋯ For these measures, there was no significant interaction between treatment and phenotype, but there was a significant interaction for pain paroxysms (0.8, 95% CI: 0.4-1.2, P < 0.001) and deep aching pain (0.6, 95% CI: 0.1-1.0, P = 0.013). In conclusion, lidocaine 5% patch had an effect on peripheral neuropathic pain, and it may be most efficacious in patients with IN phenotype. The lack of significant phenotype differences may be caused by too low statistical power.
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Meta Analysis
Decreased Pain Sensitivity Among People with Schizophrenia: A Meta-analysis of Experimental Pain Induction Studies.
Patients with schizophrenia report reduced pain sensitivity in clinical studies, but experimental studies are required to establish pain sensitivity as a potential endophenotype. We conducted a systematic review of electronic databases from database inception until April 15, 2015, including experimental studies investigating pain among patients with schizophrenia spectrum disorder vs healthy controls. A random-effect meta-analysis yielding Hedges' g ±95% confidence intervals (CIs) as the effect size (ES) measure was conducted. ⋯ Finally, greater psychiatric symptoms moderated increased pain threshold, and younger patient age moderated increased pain tolerance. Decreased pain sensitivity seems to be an endophenotype of schizophrenia spectrum disorders. How this alteration links to other dimensions of schizophrenia and physical comorbidity-related help-seeking behaviour/morbidity/mortality requires further study.
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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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Randomized Controlled Trial
Analgesic and anti-hyperalgesic effects of melatonin in a human inflammatory pain model: a randomized, double-blind, placebo-controlled, three-arm crossover study.
Antinociceptive effects of melatonin have been documented in a wide range of experimental animal models. The aim of this study was to investigate the analgesic, antihyperalgesic, and anti-inflammatory properties of melatonin using a validated burn injury (BI) model in healthy male volunteers. The design was a randomized, double-blind, placebo-controlled, three-arm crossover study. ⋯ While the BI induced large secondary hyperalgesia areas and significantly increased the markers of inflammation, no significant effects of melatonin were observed with respect to primary or secondary outcomes, compared with placebo. The administration of melatonin was not associated with any adverse effects. Melatonin did not demonstrate any analgesic, antihyperalgesic, or anti-inflammatory properties in the BI model.
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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.