The journal of pain : official journal of the American Pain Society
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The present study investigated the role of the amygdala N-methyl-d-aspartate (NMDA) receptors/nitric oxide synthase pathway in morphine-induced anti-allodynia. Concurrently with the bilateral cannulation of the central amygdala, chronic constriction of the sciatic nerve was performed on male Wistar rats. Morphine (3-5 mg/kg) was administered intraperitoneally to induce anti-allodynia. ⋯ PERSPECTIVE: Neuropathic pain is difficult to treat and the exact mechanisms remain unknown. This article suggests the importance of the amygdala glutamatergic and nitric oxide systems in morphine-induced anti-allodynia. These findings might be used in clinical studies to reach a better understanding of neuropathic pain mechanisms and treatment.
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Observational Study
Enrichment of genomic pathways based on differential DNA methylation associated with chronic postsurgical pain and anxiety in children - a prospective, pilot study.
We have reported child anxiety sensitivity (Child Anxiety Sensitivity Index [CASI]) predicts chronic postsurgical pain (CPSP). Herein, we evaluated DNA methylation profiles to understand the gene-environment interactions underlying CPSP and CASI, to identify shared, enriched, genomic pathways. In 73 prospectively recruited adolescents undergoing spine fusion, preoperative CASI and pain data over 12 months after surgery were collected. ⋯ This pilot study provides new epigenetic insights into the pathophysiology of CPSP and a basis for future studies in biomarker development and targetable interventions. PERSPECTIVE: Differential DNA methylation in regulatory genomic regions enriching shared neural pathways were associated with CPSP and CASI in adolescents undergoing spine surgery. Our findings support GABA hypofunction and the roles of the dopamine-DARPP32 pathway in emotion/reward contributing to behavioral maintenance of pain 10 to 12 months after surgery.
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Sensorimotor cortical activity is altered in both the immediate acute and chronic stages of musculoskeletal pain. However, these changes are opposite, with decreased cortical activity reported in experimentally induced acute pain (lasting minutes to hours), and increased cortical activity in chronic, clinical pain (lasting >6 months). It is unknown whether sensorimotor cortical activity is altered in acute, clinical musculoskeletal pain (lasting <4 weeks). ⋯ However, individual variation was high, suggesting individual adaptation of cortical plasticity in acute pain. PERSPECTIVE: This is the first study to examine sensorimotor cortical activity in the acute stage of clinical LBP. This information is critical for understanding the neurophysiology of acute LBP.
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The Opioid Risk Tool (ORT) is a commonly used measure of risk of aberrant drug-related behaviors in patients with chronic pain prescribed opioid therapy. In this study, the discriminant predictive validity of the ORT was evaluated in a unique cohort of patients with chronic nonmalignant pain (CNMP) on long-term opioid therapy who displayed no evidence of developing an opioid use disorder (OUD) and a sample of patients with CNMP who developed an OUD after commencing opioid therapy. Results revealed that the original ORT was able to discriminate between patients with and without OUDs (odds ratio = 1.624; 95% confidence interval [CI] = 1.539-1.715, P < .001). ⋯ A revised unweighted ORT removing the history of preadolescent sexual abuse item was notably superior in predicting the development of OUD in patients with CNMP on long-term opioid therapy (odds ratio = 3.085; 95% CI = 2.725-3.493; P < .001) with high specificity (.851; 95% CI = .811-.885), sensitivity (.854; 95% CI = .799-.898), positive predictive value (.757; 95% CI = .709-.799), and negative predictive value (.914; 95% CI = .885-.937). Perspective: The revised ORT is the first tool developed on a unique cohort to predict the risk of developing an OUD in patients with CNMP receiving opioid therapy, as opposed to aberrant drug-related behaviors that can reflect a number of other issues. The revised ORT has clinical usefulness in providing clinicians a simple, validated method to rapidly screen for the risk of developing OUD in patients on or being considered for opioid therapy.
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The effectiveness of pain-reducing interventions in newborns can only be determined if pain measurement instruments are responsive; that is, able to detect a decrease in pain intensity after the pain-reducing intervention. This review assesses the methodologic quality of studies on this measurement property-the responsiveness. We searched the literature published until January 2018 for validation studies of pain measurement instruments focusing on responsiveness to pain-reducing treatment in neonates. ⋯ PERSPECTIVE: This review focuses on the property of measurement instruments to detect changes in pain intensity after a pain-reducing intervention in neonates. We concluded that this property-the responsiveness-is under studied and that the methodologic quality of the included studies was low. Future high-quality validation studies should focus on responsiveness.