Pain
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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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Comparative Study
Influence of low doses of naltrexone on morphine antinociception and morphine tolerance in male and female rats of four strains.
In a recently proposed bimodal opioid receptor model, the inhibitory actions of opioids on action potential duration in dorsal root ganglion neurons have been proposed to produce antinociception, and the excitatory actions of hyperalgesia. Recent studies indicate that selectively blocking these excitatory actions with low doses of opioid antagonists enhances opioid antinociception and attenuates the development of opioid tolerance. To determine if the excitatory actions of opioids contribute to sex as well as strain differences in opioid sensitivity, the effects of morphine alone and in combination with low doses of naltrexone were examined in male and female rats of four strains. ⋯ In male and female Sprague-Dawley and Long-Evans rats, naltrexone enhanced morphine antinociception and attenuated the development of morphine tolerance. These effects were not observed in F344 and Lewis rats, even when tests were conducted across a range of morphine and naltrexone doses. These results suggest that the ability of low doses of naltrexone to enhance opioid antinociception does not contribute to sex or rat strain differences in opioid sensitivity.
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The true incidence of neuropathic pain is unknown, but it is believed to be under-diagnosed and treated inadequately, despite the availability of drugs with proven efficacy. Our objective was to report the epidemiology and drug treatment of neuropathic pain as managed by UK primary care physicians. A descriptive analysis of the epidemiology of incident post-herpetic neuralgia (n=12,386); trigeminal neuralgia (8268); phantom limb pain (451) and painful diabetic neuropathy (4719) and prescription treatment at diagnosis from computerised UK general practice records (GPRD): January 1992 to April 2002. ⋯ In 2600 patients followed to stable therapy, there was a median of one to two drug changes. We provide the primary care managed incidence of four neuropathic pain conditions. For commonly prescribed treatments, changes in therapy are less frequent when initial therapy was with antidepressants or anticonvulsants rather than conventional analgesics.
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Experimental models of peripheral nerve injury have been developed to study mechanisms of neuropathic pain. In the spared nerve injury (SNI) model in rats, the common peroneal and tibial nerves are injured, producing consistent and reproducible pain hypersensitivity in the territory of the spared sural nerve. In this study, we investigated whether SNI in mice is also a valid model system for neuropathic pain. ⋯ We tested two variants of the SNI model and found that injuring the tibial nerve alone induces mechanical hypersensitivity, while injuring the common peroneal and sural nerves together does not induce any significant increase in mechanical sensitivity in the territory of the spared tibial nerve. SNI induces a mechanical allodynia-like response in mice and we believe that our improved method of assessment and data analysis will reveal additional internal and external variability factors in models of persistent pain. Use of this model in genetically altered mice should be very effective for determining the mechanisms involved in neuropathic 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.