Objectives . Neuro-immune interactions with functional changes in the peripheral blood cells including changes in the transient receptor potential ankyrin 1 (TRPA1) appear to play a pivotal role in the development of chronic pain in humans. The aim of this study was to examine the association between TRPA1 DNA methylation in whole blood cells and the pain states in chronic pain patients. Methods . After collecting blood samples from 12 chronic pain patients, the authors measured DNA methylation levels in whole blood cells. Significant associations between the patient’s demographic data and the chronic pain states were determined by a multiple linear regression analysis that used age, body mass index, pain duration, depression, anxiety, cognitive impairment, activities of daily living, neuropathic pain, and pain states as the dependent variables, and the TRPA1 DNA methylation levels as the independent variables. Results . Multiple regression analysis revealed a significant correlation between increases of the methylation levels of the CpG island in the TRPA1 gene and increases in the number of neuropathic pain symptoms, which were evaluated using the Douleur Neuropathique 4 (DN4) questionnaire. Decreases in the TRPA1 mRNA expression were also significantly related to increases in the DN4 score. The presence of a burning sensation, which is one of pain symptoms in the DN4 questionnaire, was significantly correlated with the increase in DNA methylation level of TRPA1. Conclusions . TRPA1 DNA methylation levels in whole blood cells appear to be associated with pain symptoms in chronic pain patients.

We present a narrative review focusing on the new role of nociception monitor in intraoperative anesthetic management. Higher invasiveness of surgery elicits a higher degree of surgical stress responses including neuroendocrine-metabolic and inflammatory-immune responses, which are associated with the occurrence of major postoperative complications. Conversely, anesthetic management mitigates these responses. Furthermore, improper attenuation of nociceptive input and related autonomic effects may induce increased stress response that may adversely influence outcome even in minimally invasive surgeries. The original role of nociception monitor, which is to assess a balance between nociception caused by surgical trauma and anti-nociception due to anesthesia, may allow an assessment of surgical stress response. The goal of this review is to inform healthcare professionals providing anesthetic management that nociception monitors may provide intraoperative data associated with surgical stress responses, and to inspire new research into the effects of nociception monitor-guided anesthesia on postoperative complications.

Background and Objective: Pruritus (also known as itch) is defined as an unpleasant and irritating sensation of the skin that provokes an urge to scratch or rub. It is well known that opioid administration can cause pruritus, which is paradoxical as itch and pain share overlapping sensory pathways. Because opioids inhibit pain but can cause itching. Significant progress has been made to improve our understanding of the fundamental neurobiology of itch; however, much remains unknown about the mechanisms of opioid‐induced pruritus. The prevention and treatment of opioid‐induced pruritus remains a challenge in the field of pain management. The objective of this narrative review is to present and discuss the current body of literature and summarize the current understanding of the mechanisms underlying opioid‐induced pruritus, and its relationship to analgesia, and possible treatment options.Results: The incidence of opioid‐induced pruritus differs with different opioids and routes of administration, and the various mechanisms can be broadly divided into peripheral and central. Especially central mechanisms are intricate, even at the level of the spinal dorsal horn. There is evidence that opioid receptor antagonists and mixed agonist and antagonists, especially μ‐opioid antagonists and κ‐opioid agonists, are effective in relieving opioid‐induced pruritus. Various treatments have been used for opioid‐induced pruritus; however, most of them are controversial and have conflicting results.Conclusion: The use of a multimodal analgesic treatment regimen combined with a mixed antagonist and κ agonists, especially μ‐opioid antagonists, and κ‐opioid agonists, seems to be the current best treatment modality for the management of opioid‐induced pruritus and pain.Significance: Opioids remain the gold standard for the treatment of moderate to severe acute pain as well as cancer pain. It is well known that opioid‐induced pruritus often does not respond to regular antipruritic treatment, thereby posing a challenge to clinicians in the field of pain management. We believe that our review makes a significant contribution to the literature, as studies on the mechanisms of opioid‐induced pruritus and effective management strategies are crucial for the management of these patients.

Since a high neuraxial block is one of the serious complications in obstetric anesthesia, simulation training is required for the education of rapid diagnos ...

Background: MicroRNAs (miRNAs) can modulate several biological systems, including the pain system. This study aimed to evaluate the temporal expression of circulating miRNAs in the plasma of healthy volunteers as a marker for epigenetic changes before and after an acute, experimental, pain provocation by intramuscular hypertonic saline injection.Methods: Twenty volunteers were randomly allocated into two groups and received either hypertonic (pain) or isotonic (control) saline injection in the first dorsal interosseous muscle of their dominant hand. Pain intensity was continuously recorded for 20 minutes after injection on a VAS scale from 0 to 100 (0 indicates no pain and 100 the worst imaginable pain). Blood samples were taken at baseline, 30 minutes, 3 hours, and 24 hours post‐injection, and plasma was separated. MiRNA extracts were used for RNA sequencing with the Illumina NextSeq platform. MiRNA transcripts were compared between the pain and the no‐pain, control group at every time point. Significant differences were considered when folds were >2 and the False Discovery Rate wasp < 0.05.Results: After 30 minutes, 4 miRNAs were significantly altered in the pain group compared to controls, which increased to 24 after 3 hours and to 42 after 24 hours from baseline (p < 0.0001). Two miRNAs were consistently upregulated throughout the experiment. Enrichment analysis showed significant miRNAs involved in brain perception of pain, brain signalling and response to stimuli.Conclusions: This exploratory study is the first to report on the temporal expression of circulating miRNAs after an acute, human experimental muscle pain model.Significance: This exploratory study evaluated the temporal profile of circulating miRNAs in the plasma of healthy subjects after acute experimental pain. Several miRNAs were altered in subjects at the times of follow‐up after the acute pain model when compared to controls. MiRNAs previously associated with pain processes were altered in the pain group. Our results, by showing the fast and prolonged modifications of miRNA elicited by the acute experimental pain model, add new perspectives to the topic of epigenetics and pain.