Human Studies

Multicentre cross-sectional study.

The role that inflammation plays in human nerve injury and neuropathic pain is incompletely understood. Previous studies highlight the role of inflammation in the generation and maintenance of neuropathic pain, but the emerging evidence from the preclinical literature for its role in the resolution of neuropathic pain remains to be explored in humans. Here, we use carpal tunnel syndrome (CTS) as a human model system of nerve injury and neuropathic pain to determine changes in serum cytokine protein levels and gene expression levels before (active stage of disease) and after carpal tunnel decompression surgery (recovery). Fifty-five CTS patients were studied and 21 healthy age and gender matched participants served as controls. In the active stage of the disease (CTS before surgery vs healthy controls), PTGES2 mRNA was decreased in patients (adjusted p=0.013), while TGF-β and CCL5 protein levels were increased (adjusted p=0.016 and p=0.047 respectively). In the resolution phase (CTS before surgery vs after surgery), IL-9 mRNA was increased after surgery (adjusted p=0.014) and expression of IL-6 mRNA and IL-4 protein levels were increased before surgery (adjusted p=0.034 and p=0.002 respectively). IL-9 mRNA expression negatively correlated with several (neuropathic) pain scores. In contrast, protein levels of IL-4 positively correlated with pain scores. In conclusion, we demonstrate specific dysregulation of systemic cytokine expression both in the active and resolution phases of nerve injury and neuropathic pain. IL-9 represents an interesting candidate associated with resolution of nerve injury and neuropathic pain.

Disruptions caused by the COVID-19 pandemic could disproportionately affect the health of vulnerable populations, including patients experiencing persistent health conditions (i.e., chronic pain), along with populations living within deprived, lower socioeconomic areas. The current cross-sectional study characterized relationships between neighborhood deprivation and perceived changes in pain-related experiences during the COVID-19 pandemic (early-September to mid-October 2020) for adult patients (N = 97) with nonspecific chronic low back pain.

The purpose of this study was to evaluate changes in pain intensity among Veterans transitioning from long-term opioid therapy (LTOT) to either intermittent therapy or discontinuation compared to continued LTOT. Pain intensity was assessed using the Numeric Rating Scale in 90-day increments starting in the 90-day period prior to potential opioid transitions and the two ensuing 90-day periods after transition. Primary analyses used a 1:1 greedy propensity matched sample. A total of 29,293 Veterans switching to intermittent opioids and 5,972 discontinuing opioids were matched to Veterans continuing LTOT. Covariates were well balanced after matching except minor differences in baseline mean pain scores. Pain scores were lower in the follow up periods for those switching to intermittent opioids and discontinuing opioids compared to those continuing LTOT (0-90 days: Intermittent: 3.79, 95%CI: 3.76, 3.82; LTOT: 4.09, 95%CI: 4.06, 4.12, p<0.0001; Discontinuation: 3.06, 95%CI: 2.99, 3.13; LTOT: 3.86, 95%CI: 3.79, 3.94, p=<0.0001; 91-180 days: Intermittent: 3.76, 95%CI: 3.73, 3.79; LTOT: 3.99, 95%CI: 3.96, 4.02, p<0.0001; Discontinuation: 3.01, 95%CI: 2.94, 3.09; LTOT: 3.80, 95%CI: 3.73, 3.87, p=<0.0001). Sensitivity analyses found similar results. Discontinuing opioid therapy or switching to intermittent opioid therapy was not associated with increased pain intensity. Perspective: This article evaluates the association of switching to intermittent opioid therapy or discontinuing opioids with pain intensity after using opioids long-term. Pain intensity decreased after switching to intermittent therapy or discontinuing opioids, but remained relatively stable for those continuing long-term opioid therapy. Switching to intermittent opioids or discontinuing opioids was not associated with increased pain intensity.

Given the national opioid crisis, post-operative analgesia at discharge must be thoughtfully prescribed. Data, specifically related to thoracic procedures, remains scarce. This study assesses adequacy of pain control with standardized and limited opioids after thoracic procedures.