European journal of pain : EJP
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The objective of this paper is to test and correct for systematic differences in reporting of pain severity among older adults by age, gender, ethnic group and socio-economic status using anchoring vignettes. Data from a national survey of community-dwelling older Singaporeans (aged 60 years and over) conducted in 2009 was used. Respondents were asked to rate the severity of their own pain as well as that of others described in the vignettes on a five-point scale ranging from none to extreme. ⋯ However, after correcting for reporting heterogeneity, while women and those older were found to have an even greater severity of pain than what they had reported, Malays were found to have a lower severity of pain than what they had reported. We conclude that there are systematic differences in reporting pain severity by age, gender and ethnic group. We propose that pain management may be improved if medical professionals take into account reporting heterogeneity for pain severity among various population sub-groups in Singapore.
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Targeting supraspinal pain control centers by gene transfer is known to induce sustained analgesia. In this study, we evaluated the effects of injecting a Herpes Simplex Virus type 1 vector which expresses enkephalin (HSV-ENK vector) in the lateralmost part of the caudal ventrolateral medulla (VLMlat), a pain control center that exerts mainly descending inhibitory effects on pain modulation. Overexpression of enkephalin at the VLMlat reduced the number of flinches during the early and delayed phases of the formalin test and decreased c-fos expression in the spinal cord. ⋯ Virally driven-enkephalin was expressed from transduced neurons located in the VLMlat and, at lower extent, in the rostral ventromedial medulla. Our results show that HSV-mediated expression of enkephalin in the VLMlat induced antinociceptive effects, likely due to an enhancement of the opioidergic input to the VLMlat which accounted for descending inhibition of the nociceptive transmission at the spinal cord. This study also demonstrates the value of HSV-1 derived vectors to manipulate, in a sustained and directed manner, pain modulatory pathways in the brain, which is important in the study of supraspinal pain control circuits.
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Although spinal cord stimulation (SCS) is an established therapy for chronic neuropathic pain, still 30% of patients do not respond adequately to trial stimulation. These so called "non-responders" do not receive a permanent implantation for pain relief. The induction and maintenance of central sensitization plays a pivotal role in (chronic) neuropathic pain and is thought to be the resultant of the activation of the N-methyl-d-aspartate (NMDA) receptor in the dorsal horn. ⋯ Non-responders to SCS (n=8) received their individually determined sub-effective i.t. dose of ketamine followed by 30 min of SCS. No side effects of the sub-effective dose of ketamine could be noted. The combined treatment of SCS and sub-effective dose of i.t. ketamine in non-responders resulted in a significant reduction of the withdrawal threshold in all previous non-responders to SCS, thereby converting them into responders to SCS.