Pain
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Randomized Controlled Trial Comparative Study
Lumbar instrumented fusion compared with cognitive intervention and exercises in patients with chronic back pain after previous surgery for disc herniation: a prospective randomized controlled study.
The effectiveness of lumbar fusion for chronic low back pain after surgery for disc herniation has not been evaluated in a randomized controlled trial. The aim of the present study was to compare the effectiveness of lumbar fusion with posterior transpedicular screws and cognitive intervention and exercises. Sixty patients aged 25-60 years with low back pain lasting longer than 1 year after previous surgery for disc herniation were randomly allocated to the two treatment groups. ⋯ The mean difference between treatments after adjustment for gender was -7.3 (95% CI -17.3 to 2.7, p=0.15). The success rate was 50% in the fusion group and 48% in the cognitive intervention/exercise group. For patients with chronic low back pain after previous surgery for disc herniation, lumbar fusion failed to show any benefit over cognitive intervention and exercises.
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Clinical Trial
Physical and psychological factors maintain long-term predictive capacity post-whiplash injury.
Higher initial levels of pain and disability, older age, cold hyperalgesia, impaired sympathetic vasoconstriction and moderate post-traumatic stress symptoms have been shown to be associated with poor outcome 6 months following whiplash injury. This study prospectively investigated the predictive capacity of these variables at a long-term follow-up. Sixty-five of an initial cohort of 76 acutely injured whiplash participants were followed to 2-3 years post-accident. ⋯ The latter two groups showed only persistent deficits in cervical muscle recruitment patterns. Higher initial NDI scores (OR 1.00-1.1), older age (OR 1.00-1.13), cold hyperalgesia (OR 1.1-1.13) and post-traumatic stress symptoms (OR 1.03-1.2) remained significant predictors of poor outcome at long-term follow-up (r2=0.56). The robustness of these physical and psychological factors suggests that their assessment in the acute stage following whiplash injury will be important.
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Chronic opioid-induced analgesic tolerance remains a major obstacle to improving clinical management of moderate to severe chronic pain. Our understanding of the underlying mechanisms for opioid tolerance is only partially understood at present. In this study, we investigated the effects of chronic morphine on GABA(A) receptor-mediated synaptic transmission, a major opioid target for pain inhibition, and the behavioral role of GABA synaptic transmission in the development of morphine tolerance. ⋯ Behaviorally, a low dose of GABA(A) receptor antagonist bicuculline microinjected into the NRM, ineffective alone, blocked morphine antinociception in control rats, but failed to do so in morphine-tolerant rats. With chronic treatment through daily NRM microinjections, bicuculline augmented the development of morphine tolerance, whereas the GABA(A) receptor agonist muscimol or H89 significantly attenuated the development of morphine tolerance. These results suggest that chronic morphine increases GABA synaptic activity through upregulation of the AMP system in morphine-tolerant NRM neurons and that while chronic GABA(A) receptor antagonism in the NRM augments morphine tolerance, chronic activation of NRM GABA(A) receptors or PKA inhibition reduces morphine tolerance with increased analgesic efficacy of chronic morphine.
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Randomized Controlled Trial
A sham-controlled, phase II trial of transcranial direct current stimulation for the treatment of central pain in traumatic spinal cord injury.
Past evidence has shown that motor cortical stimulation with invasive and non-invasive brain stimulation is effective to relieve central pain. Here we aimed to study the effects of another, very safe technique of non-invasive brain stimulation--transcranial direct current stimulation (tDCS)--on pain control in patients with central pain due to traumatic spinal cord injury. Patients were randomized to receive sham or active motor tDCS (2mA, 20 min for 5 consecutive days). ⋯ Furthermore, cognitive performance was not significantly changed throughout the trial in both treatment groups. The results of our study suggest that this new approach of cortical stimulation can be effective to control pain in patients with spinal cord lesion. We discuss potential mechanisms for pain amelioration after tDCS, such as a secondary modulation of thalamic nuclei activity.
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Randomized Controlled Trial
Psychophysical study of the effects of topical application of menthol in healthy volunteers.
Cold hyperalgesia is a major clinical phenomenon, but validated experimental models are still lacking for humans. Topical menthol application has recently been proposed as a possible model for the study of cold pain. We characterized the psychophysical effects of 30% l-menthol in ethanol on glabrous skin in 39 healthy subjects, using a double-blind, randomized, crossover design, with ethanol as a control. ⋯ No subject displayed signs of skin irritation or redness. These data suggest that 30% menthol application may be a useful experimental model for studies of cold hyperalgesia in humans. The absence of local skin reactions also makes this test potentially suitable for use in patients.