Pain
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The contribution of the peripheral nervous system to opiate-induced hyperalgesia (OIH) is not well understood. In this study, we determined the changes in excitability of primary sensory neurons after sustained morphine administration for 7 days. Changes in the expression of glutamate receptors and glutamate transporters after morphine administration were ascertained in dorsal root ganglions. ⋯ Coadministration in vivo of the GluN2B selective antagonist Ro 25-6981 with morphine for 7 days prevented the appearance of OIH and increased morphine-induced analgesia. Administration of morphine for 7 days led to an increased expression of GluN2B and excitatory amino acid transporter 3/excitatory amino acid carrier 1, but not of the α-amino-3-hydroxy-5-methyl-4-isoxazole propionate, kainate, or group I metabotropic glutamate receptors, or of the vesicular glutamate transporter 2. These results suggest that peripheral glutamatergic neurotransmission contributes to OIH and that GluN2B subunit of NMDA receptors in the periphery may be a target for therapy.
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Randomized Controlled Trial Multicenter Study
Internet-delivered Cognitive-behavioral Treatment for Adolescents with Chronic Pain and their Parents: A Randomized Controlled Multicenter Trial.
Internet-delivered interventions are emerging as a strategy to address barriers to care for individuals with chronic pain. This is the first large multicenter randomized controlled trial of Internet-delivered cognitive-behavioral therapy (CBT) for pediatric chronic pain. Participants included were 273 adolescents (205 females and 68 males), aged 11 to 17 years with mixed chronic pain conditions and their parents, who were randomly assigned in a parallel-group design to Internet-delivered CBT (n = 138) or Internet-delivered Education (n = 135). ⋯ On secondary outcomes, significant beneficial effects of Internet CBT were found on sleep quality (b = 0.14, P = 0.04), on reducing parent miscarried helping (b = -2.66, P = 0.007) and protective behaviors (b = -0.19, P = 0.001), and on treatment satisfaction (P values < 0.05). On exploratory outcomes, benefits of Internet CBT were found for parent-perceived impact (ie, reductions in depression, anxiety, self-blame about their adolescent's pain, and improvement in parent behavioral responses to pain). In conclusion, our Internet-delivered CBT intervention produced a number of beneficial effects on adolescent and parent outcomes, and could ultimately lead to wide dissemination of evidence-based psychological pain treatment for youth and their families.
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Both sympathetic and parasympathetic nervous systems are involved in regulating pain states. The activity of these systems seems to become disturbed in states of chronic pain. This disruption in autonomic balance can be measured through the assessment of heart rate variability (HRV), that is, the variability of the interval between consecutive heart beats. ⋯ High heterogeneity aside, pooled results from the meta-analyses reflected a consistent, moderate-to-large effect of decreased high-frequency HRV in chronic pain, implicating a decrease in parasympathetic activation. These effects were heavily influenced by fibromyalgia studies. Future research would benefit from wider use of standardised definitions of measurement, and also investigating the synergistic changes in pain state and HRV throughout the development and implementation of mechanism-based treatments for chronic pain.
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Multicenter Study
Frequency, Impact, and Predictors of Persistent Pain Following Root Canal Treatment: A National Dental PBRN Study.
Root canal treatment (RCT) is commonly performed surgery and persistent pain is known to occur, but little is known about how these patients are affected by this pain. Although biopsychosocial mechanisms are thought to be associated with the development of such pain, similar to persistent pain after surgery in other body sites, little is known about the baseline predictors for persistent pain. We assessed the frequency of persistent pain 6 months after RCT, measured the impact this pain had on patients, and determined predictive factors for persistent tooth pain in a multicenter prospective cohort study conducted within the National Dental Practice-Based Research Network. ⋯ After adjusting for the type of dental practitioner and patient age, gender, and household income, pain duration over the week before RCT significantly increased the risk of developing persistent pain (odds ratio = 1.19 per 1 day increase in pain duration, 95% confidence interval: 1.07-1.33), whereas optimism about the procedure reduced the risk (odds ratio = 0.39, 95% confidence interval: 0.22-0.67). Our data suggest that persistent pain 6 months after RCT is fairly common, but generally does not have a large impact on those experiencing it. Furthermore, patient age and gender did not predict persistent pain, whereas preoperative pain duration and the patient's expectation did.