Pain
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Neuropathic pain is a debilitating chronic syndrome that often arises from injuries to peripheral nerves. Such pain has been hypothesized to be the result of an aberrant expression and function of sodium channels at the site of injury. ⋯ These data provide direct evidence linking NaV1.8 to neuropathic pain. As NaV1.8 expression is restricted to sensory neurons, this channel offers a highly specific and effective molecular target for the treatment of neuropathic pain.
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The descending colon and rectum are innervated by primary afferent fibers projecting to the lumbosacral and thoracolumbar spinal cord segments. Previous work from this laboratory has suggested that afferent input and sensory processing in the lumbosacral spinal cord is necessary and sufficient to mediate reflex responses to transient colorectal stimulation while processing in both the lumbosacral and thoracolumbar spinal cord segments contribute to visceral hyperalgesia. In the rat, repetitive noxious colorectal distention (CRD) induces >200 Fos labeled cells per section in the lumbosacral segments, but few in the thoracolumbar segments, further suggesting that transient colonic nociceptive input is transduced primarily in the lumbosacral spinal cord. ⋯ Colonic inflammation plus CRD did not significantly increase the percentage of spinoparabrachial neurons that were labeled for Fos compared to distention alone. (4) In the thoracolumbar spinal cord less than 10% of the FG labeled neurons were double labeled for Fos following CRD, but 25% of the FG labeled neurons in the SDH were double labeled following colonic inflammation. These data support the hypothesis that colonic inflammation activates viscerosensory processing in the thoracolumbar spinal cord and further suggests that this information is relayed to the PBn. The increase in information reaching the PBn over these parallel pathways may contribute to the affective-motivational component of the pain experience.
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Pain-related somatosensory-evoked potential following CO(2) laser stimulation (laser-evoked potential (LEP)) is now used not only for research objectives, but also for clinical applications. Estimating the conduction velocity (CV) of the spinothalamic tract (STT) by analyzing LEP following activation of Adelta-fibers (Adelta-CVSTT) by CO(2) laser stimulation has been performed previously, but estimating the CV of STT following activation of C-fibers (C-CVSTT) has not. This is the first report to estimate the C-CVSTT in humans; by using the novel method of CO(2) laser stimulation applied to tiny skin areas. ⋯ The nociceptive signal of the C-fibers in STT is probably conveyed by unmyelinated axons of projection neurons to reach the thalamus. Our findings provide the first physiological evidence of the signals ascending through unmyelinated axons in the spinal cord in humans. In addition, estimating C-CVSTT and Adelta-CVSTT combined with conventional methods to measure the CV of the posterior column using electrical stimulation should be useful and have important clinical applications, particularly in patients with spinal cord lesions showing various kinds of sensory disturbances.
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Randomized Controlled Trial Comparative Study Clinical Trial
Is there a right treatment for a particular patient group? Comparison of ordinary treatment, light multidisciplinary treatment, and extensive multidisciplinary treatment for long-term sick-listed employees with musculoskeletal pain.
In general, randomized controlled studies concerning return to work have failed to demonstrate significant treatment effects for long-lasting musculoskeletal pain, and most treatments examined have not been economically beneficial. Individuals (n=654) sick-listed for at least 8 weeks with musculoskeletal pain, selected from the Norwegian mandatory sickness insurance system and volunteering to participate, were categorized into three groups differing in a prognosis score (good, medium, poor) for return to work, based on a brief, standardized screening of psychological and physiotherapy findings. They were then randomly assigned to three outpatient treatments with three different levels of intensity (ordinary treatment, light multidisciplinary, and extensive multidisciplinary treatment). ⋯ Measures of pain or quality of life are not included in this study. The cost-benefit analysis of the economic returns of the light multidisciplinary and the extensive multidisciplinary treatment programs yields a positive net present social value of the treatment. A simple, standardized, screening instrument including only psychological and physiotherapeutic observations may be a useful clinical tool for allocating patients with musculoskeletal pain to the right level of treatment.