Pain
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Neurosteroids are potent blockers of neuronal low-voltage activated (T-type) Ca(2+) channels and potentiators of GABA(A) ligand-gated channels, but their effects in peripheral pain pathways have not been studied previously. To investigate potential analgesic effects and the ion channels involved, we tested the ability of locally injected 5alpha-reduced neurosteroids to modulate peripheral thermal nociception to radiant heat in adult rats in vivo and to modulate GABA(A) and T-type Ca(2+) channels in vitro. The steroid anesthetic alphaxalone (ALPX), the endogenous neurosteroid allopregnanolone (3alpha5alphaP), and a related compound ((3alpha,5alpha,17beta)-3-hydroxyandrostane-17-carbonitrile, (ACN)), induced potent, dose-dependent, enantioselective anti-nociception in vivo and modulation of both T-type Ca(2+) currents and GABA(A)-mediated currents in vitro. ⋯ These results strongly suggest that GABA(A) channels do not contribute to baseline pain transmission, but they can enhance anti-nociception mediated by blockade of T-type Ca(2+) channels. In conclusion, we demonstrate that potent peripheral analgesia induced by 5alpha-reduced neurosteroid is mediated in part by effects on T-type Ca(2+) channels. Our results also reveal a role of GABA-gated ion channels in peripheral nociceptive signaling.
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Randomized Controlled Trial Clinical Trial
Prognostic factors for poor recovery in acute whiplash patients.
The objective of our prospective inception cohort study was to identify prognostic factors for poor recovery in patients with whiplash-associated disorders grade 1 or 2 who still had neck pain and accompanying complaints 2 weeks after the accident. The study was carried out in a primary health care setting in The Netherlands and included 125 patients. The primary outcome measure was functional recovery defined in terms of neck pain intensity or work disability without medication use. ⋯ The accuracy of the predictions of the prognostic models was high, meaning that the models adequately distinguished patients with poor recovery from those regarded as recovered. These findings add to the growing body of evidence, indicating that socio-demographic, physical and psychological factors affect short- and long-term outcome after whiplash injury. Our findings also indicate that care providers can easily identify patients at risk for poor recovery with a visual analogue scale for initial pain intensity and work-related activities.
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Randomized Controlled Trial Clinical Trial
Auricular acupuncture for pain relief after total hip arthroplasty - a randomized controlled study.
Auricular acupuncture (AA) is known to be effective in treatment of various pain conditions, but still there have been no randomized controlled studies of AA for treatment of acute postoperative pain. Therefore we tested whether AA of specific points is superior to sham acupuncture for complementary analgesia after total hip arthroplasty in a patient-anesthesiologist-evaluator-analyst blinded study. The patients were randomly allocated to receive true AA (lung, shenmen, thalamus and hip points) or sham procedure (4 non-acupuncture points on the auricular helix). ⋯ Pain intensity on VAS-100 and incidence of analgesia-related side effects were similar in both groups. The differences between the groups as regard patients' opinions concerning success of blinding were not significant. Findings from our study demonstrate that AA could be used to reduce postoperative analgesic requirement.
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This study examined gender differences in smoking-related analgesia and stress-induced analgesia (SIA), as a function of pain modality. Forty men (20 smokers, 20 nonsmokers) and 37 women (17 smokers) were tested twice for pain sensitivity to tourniquet ischemia, thermal heat, and cold pressor tests; once following mental stress and once following rest control, counterbalancing order. Cardiovascular and neuroendocrine responses to mental stress were also examined. ⋯ Smokers showed evidence for blunted HPA-axis function at rest and stress. These results indicate that analgesia related to both being a smoker and stress is influenced by gender and pain modality. The reduced pain perception in smokers and absence of relationships between endogenous pain regulatory mechanisms and pain sensitivity may reflect a maladaptive response to chronic smoking.
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The purpose of this study was to predict post-settlement pain intensity, psychological distress, disability, and financial struggle among African American (n=580) and non-Hispanic Caucasian (n=892) Workers' Compensation claimants with single incident low back injury. The study was a population-based telephone survey conducted in three population centers in Missouri. ⋯ The results suggest that African American race and lower SES-relative to Caucasian race and higher SES-are risk factors for poor outcomes after occupational low back injury. Mechanisms to explain these associations are discussed, including patient-level, provider-level, legal, and Workers' Compensation system-level factors.