Pain
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Review Meta Analysis
Do sex differences exist in opioid analgesia? A systematic review and meta-analysis of human experimental and clinical studies.
Although a contribution of sex in opioid efficacy has garnered much attention, the confirmation and direction of any such difference remain elusive. We performed a systematic review of the available literature on sex differences in μ and mixed μ/κ opioid effect on acute and experimental pain. Fifty unique studies (including three unpublished studies) were included in the analyses. ⋯ Female patients had greater μ/κ opioid analgesia (n=7, effect size 0.84; 95% c.i. 0.25-1.43, P=0.005), but no sex-analgesia association was present in experimental studies (n=7). Sex differences exist in morphine-induced analgesia in both experimental pain studies and clinical PCA studies, with greater morphine efficacy in women. The data on non-morphine μ and mixed μ/κ-opioids are less convincing and require further study.
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Randomized Controlled Trial Multicenter Study Clinical Trial
German Randomized Acupuncture Trial for chronic shoulder pain (GRASP) - a pragmatic, controlled, patient-blinded, multi-centre trial in an outpatient care environment.
The German Randomized Acupuncture Trial for chronic shoulder pain (GRASP) comprised 424 outpatients with chronic shoulder pain (CSP) > or =6 weeks and an average pain score of VAS > or =50 mm, who were randomly assigned to receive Chinese acupuncture (verum), sham acupuncture (sham) or conventional conservative orthopaedic treatment (COT). The patients were blinded to the type of acupuncture and treated by 31 office-based orthopaedists trained in acupuncture; all received 15 treatments over 6 weeks. The 50% responder rate for pain was measured on a VAS 3 months after the end of treatment (primary endpoint) and directly after the end of the treatment (secondary endpoint). ⋯ In the ITT (n=424) analysis, percentages of responders for the primary endpoint were verum 65% (95% CI 56-74%) (n=100), sham 24% (95% CI 9-39%) (n=32), and COT 37% (95% CI 24-50%) (n=50); secondary endpoint: verum 68% (95% CI 58-77%) (n=92), sham 40% (95% CI 27-53%) (n=53), and COT 28% (95% CI 14-42%) (n=38). The results are significant for verum over sham and verum over COT (p<0.01) for both the primary and secondary endpoints. The PPP analysis of the primary (n=308) and secondary endpoints (n=360) yields similar responder results for verum over sham and verum over COT (p<0.01). Descriptive statistics showed greater improvement of shoulder mobility (abduction and arm-above-head test) for the verum group versus the control group immediately after treatment and after 3 months. The trial indicates that Chinese acupuncture is an effective alternative to conventional orthopaedic treatment for CSP.
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Randomized Controlled Trial Clinical Trial
Predicting the analgesic effect to oxycodone by 'static' and 'dynamic' quantitative sensory testing in healthy subjects.
The large inter-individual variability in the magnitude of analgesia in response to opioids and the high prevalence of adverse events associated with their use underline the clinical importance of being able to predict who will or will not respond to opioid treatment. The present study used both static and dynamic quantitative sensory testing (QST) on 40 healthy volunteers in order to test whether this methodology can predict the analgesic effects of oral oxycodone, as compared to a placebo, on latency to onset, pain intensity, and tolerance to the cold pressor test (CPT). Static QST consisted of measuring heat and cold pain thresholds. ⋯ The static QST results showed that heat pain thresholds predicted the magnitude of reduction in pain intensity in response to oxycodone treatment (F((1,22))=5.63, p=0.027, R(2)=0.17). The dynamic QST results showed that TS predicted the effect of oxycodone on the tolerance to CPT (F((1,38))=9.11, p=0.005, R(2)=0.17). These results suggest that both static and dynamic QST have the potential to be useful in the prediction of the response to opioid treatment.
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Randomized Controlled Trial Clinical Trial
NMDA-receptor antagonist and morphine decrease CRPS-pain and cerebral pain representation.
A combination therapy of morphine with an NMDA-receptor antagonist might be more effective than morphine without a NMDA-receptor antagonist for the relief of neuropathic pain in patients with complex regional pain syndrome (CRPS). In order to test the efficacy of this combination therapy we performed a double-blind randomized placebo-controlled study on patients suffering from CRPS of the upper extremity. We used functional magnetic resonance imaging during movement of the affected and unaffected upper hand before and after a treatment regimen of 49 days that contrasted morphine and an NMDA-receptor antagonist with morphine and placebo. ⋯ Pain relief during therapy was related to decreased activation in cS1 and secondary somatosensory cortex (S2). Our data suggest that the combination of morphine with an NMDA-receptor antagonist significantly affects the cerebral processing of nociceptive information in CRPS. The correlation of pain relief and decrease in cortical activity in cS1 and S2 is in accordance with the expected impact of the NMDA-receptor antagonist on cerebral pain processing with emphasis on sensory-discriminative aspects of pain.
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Randomized Controlled Trial Clinical Trial
Deciphering the role of endogenous opioids in high-frequency TENS using low and high doses of naloxone.
Previous human studies have shown that the analgesic effect of high-frequency TENS could not be reversed by low doses of naloxone. The aim of the present study was to reinvestigate the possible contribution of opioid receptors to high-frequency TENS analgesia by using low (0.02 mg/kg) and high (0.14 mg/kg) doses of naloxone. Naloxone (high and low doses) and saline were administered intravenously to young healthy adults using a triple-blind randomized cross-over design. ⋯ However, when a high dose of naloxone was administered, TENS analgesia was completely blocked (p=.20). These results suggest that high-frequency TENS involves opioid receptors. An insufficient amount of opioid antagonist likely prevented previous human studies from discovering the importance of opioid receptors in producing high-frequency TENS analgesia.