Pain
-
Animal and human studies have shown that exercise prior to nerve injury prevents later chronic pain, but the mechanisms of such preconditioning remain elusive. Given that exercise acutely increases the formation of free radicals, triggering antioxidant compensation, we hypothesized that voluntary running preconditioning would attenuate neuropathic pain by supporting redox homeostasis after sciatic nerve injury in male and female rats. We show that 6 weeks of voluntary wheel running suppresses neuropathic pain development induced by chronic constriction injury across both sexes. ⋯ The protective effects of prior voluntary wheel running were mediated by Nrf2, as suppression was abolished across both sexes when Nrf2 activation was blocked during the 6-week running phase. This study provides insight into the mechanisms by which physical activity may prevent neuropathic pain. Preconditioning by voluntary wheel running, terminated prior to nerve injury, suppresses later neuropathic pain in both sexes, and it is modulated through the activation of Nrf2-antioxidant signaling.
-
This study examined the efficacy of internet-delivered cognitive and behavioural interventions for adults with chronic pain AND explored the role of clinical and study characteristics as moderators of treatment effects. PubMed, Embase, PsycINFO, CENTRAL and CINAHL were searched to identify randomized controlled trials published up to October 2021. A meta-analysis of 36 studies (5778 participants) was conducted, which found small effect sizes for interference/disability (Hedges' g = 0.28; 95% confidence interval [CI] 0.21-0.35), depression ( g = 0.43; 95% CI 0.33-0.54), anxiety ( g = 0.32; 95% CI 0.24-0.40), pain intensity ( g = 0.27; 95% CI 0.21-0.33), self-efficacy ( g = 0.39; 95% CI 0.27-0.52) and pain catastrophizing ( g = 0.31; 95% CI 0.22-0.39). ⋯ No differences were found between treatments based on traditional cognitive behaviour therapy vs acceptance and commitment therapy. Sample size, study year, and overall risk of bias (Cochrane rating) did not consistently moderate treatment effects. Overall, the results support the use of internet-delivered cognitive and behavioural interventions as efficacious and suggest guided interventions are associated with greater clinical gains for several key pain management outcomes.
-
Meta Analysis
Pain mechanisms in carpal tunnel syndrome: a systematic review and meta-analysis of quantitative sensory testing outcomes.
Carpal tunnel syndrome (CTS) is the most common nerve compression in the arm. A mix of peripheral and central contributions on quantitative sensory testing (QST) has been reported in the literature. Thus, this systematic review or meta-analysis aimed to identify the dominant sensory phenotype and draw conclusive evidence about the presence of central sensitization (CS) in CTS. ⋯ Furthermore, there was a significant increase in mechanical pain sensitivity in median nerve territories and remotely in the forearm ( P < 0.05) and a significant gain in pressure and heat pain thresholds in the carpal area ( P < 0.05). Conditioned pain modulation was impaired in CTS. Hypoesthesia and increased thermal and mechanical pain ratings are the dominant sensory phenotype with inconclusive evidence about CS in CTS due to the heterogenous results of thermal and mechanical pain thresholds.
-
Higher body mass and obesity are associated with bodily pain, and rates of chronic pain increase among older adults. Most past studies are cross-sectional, precluding determination of the temporal relationship between body mass and pain. A longitudinal study of body mass and pain among middle-aged adults found that higher body mass index (BMI) led to greater lower back pain. ⋯ In addition, the relationship changed with age, until approximately age 80 years, increasing joint pain contributed to higher BMI, but after that time increasing joint pain contributed to lower BMI. In addition, sex differences in the relationship between BMI and pain appeared after age 70 years. Thus, joint pain contributes to changes in BMI among middle-aged and older adults, but the relationship may change by age and sex.
-
Randomized Controlled Trial
Pain response to cannabidiol in opioid-induced hyperalgesia, acute nociceptive pain, and allodynia using a model mimicking acute pain in healthy adults in a randomized trial (CANAB II).
Opioids in general and remifentanil in particular can induce hyperalgesia. Preclinical data suggest that cannabidiol might have the capacity to reduce opioid-induced hyperalgesia (OIH). Thus, we investigated the effect of oral cannabidiol on OIH in healthy volunteers using an established pain model. ⋯ Cannabidiol was well tolerated. We conclude that a high single-oral dose of 1600-mg cannabidiol is not effective in reducing OIH. Before excluding an effect of cannabidiol on OIH, research should focus on drug formulations enabling higher cannabidiol concentrations.