Multicenter, Randomized, Placebo-controlled Crossover Trial Evaluating Topical Lidocaine for Mechanical Cervical Pain.

BACKGROUND: There are few efficacious treatments for mechanical neck pain, with controlled trials suggesting efficacy for muscle relaxants and topical nonsteroidal anti-inflammatory drugs. Although studies evaluating topical lidocaine for back pain have been disappointing, the more superficial location of the cervical musculature suggests a possible role for topical local anesthetics. METHODS: This study was a randomized, double-blind, placebo-controlled crossover trial performed at four U.S. military, Veterans Administration, academic, and private practice sites, in which 76 patients were randomized to receive either placebo followed by lidocaine patch for 4-week intervals (group 1) or a lidocaine-then-placebo patch sequence. The primary outcome measure was mean reduction in average neck pain, with a positive categorical outcome designated as a reduction of at least 2 points in average neck pain coupled with at least a 5-point score of 7 points on the Patient Global Impression of Change scale at the 4-week endpoint. RESULTS: For the primary outcome, the median reduction in average neck pain score was -1.0 (interquartile range, -2.0, 0.0) for the lidocaine phase versus -0.5 (interquartile range, -2.0, 0.0) for placebo treatment (P = 0.17). During lidocaine treatment, 27.7% of patients experienced a positive outcome versus 14.9% during the placebo phase (P = 0.073). There were no significant differences between treatments for secondary outcomes, although a carryover effect on pain pressure threshold was observed for the lidocaine phase (P = 0.015). A total of 27.5% of patients in the lidocaine group and 20.5% in the placebo group experienced minor reactions, the most common of which was pruritis (P = 0.36). CONCLUSIONS: The differences favoring lidocaine were small and nonsignificant, but the trend toward superiority of lidocaine suggests more aggressive phenotyping and applying formulations with greater penetrance may provide clinically meaningful benefit.

Rectus Abdominis Muscle Atrophy and Asymmetry After Pulmonary Lobectomy.

INTRODUCTION: Pulmonary lobectomy can result in intercostal nerve injury, leading to denervation of the rectus abdominis (RA) resulting in asymmetric muscle atrophy or an abdominal bulge. While there is a high rate of intercostal nerve injury during thoracic surgery, there are no studies that evaluate the magnitude and predisposing factors for RA atrophy in a large cohort. METHODS: A retrospective chart review was conducted of 357 patients who underwent open, thoracoscopic or robotic pulmonary lobectomy at a single academic center. RA volumes were measured on computed tomography scans preoperatively and postoperatively on both the operated and nonoperated sides from the level of the xiphoid process to the thoracolumbar junction. RA volume change and association of surgical/demographic characteristics was assessed. RESULTS: Median RA volume decreased bilaterally after operation, decreasing significantly more on the operated side (-19.5%) versus the nonoperated side (-6.6%) (P < 0.0001). 80.4% of the analyzed cohort experienced a 10% or greater decrease from preoperative RA volume on the operated side. Overweight individuals (body mass index 25.5-29.9) experienced a 1.7-fold greater volume loss on the operated side compared to normal weight individuals (body mass index 18.5-24.9) (P = 0.00016). In all right-sided lobectomies, lower lobe resection had the highest postoperative volume loss (Median (interquartile range): -28 (-35, -15)) (P = 0.082). CONCLUSIONS: This study of postlobectomy RA asymmetry includes the largest cohort to date; previous literature only includes case reports. Lobectomy operations result in asymmetric RA atrophy and predisposing factors include demographics and surgical approach. Clinical and quality of life outcomes of RA atrophy, along with mitigation strategies, must be assessed.

Microglia depletion ameliorates neuroinflammation, anxiety-like behavior, and cognitive deficits in a sex-specific manner in Rev-erbα knockout mice.

The circadian system is an evolutionarily adaptive system that synchronizes biological and physiological activities within the body to the 24 h oscillations on Earth. At the molecular level, circadian clock proteins are transcriptional factors that regulate the rhythmic expression of genes involved in numerous physiological processes such as sleep, cognition, mood, and immune function. Environmental and genetic disruption of the circadian clock can lead to pathology. For example, global deletion of the circadian clock gene Rev-erbα (RKO) leads to hyperlocomotion, increased anxiety-like behaviors, and cognitive impairments in male mice; however, the mechanisms underlying behavioral changes remain unclear. Here we hypothesized that RKO alters microglia function leading to neuroinflammation and altered mood and cognition, and that microglia depletion can resolve neuroinflammation and restore behavior. We show that microglia depletion (CSF1R inhibitor, PLX5622) in 8-month-old RKO mice ameliorated hyperactivity, memory impairments, and anxiety/risky-like behaviors. RKO mice exhibited striking increases in expression of pro-inflammatory cytokines (e.g., IL-1ß and IL-6). Surprisingly, these increases were only fully reversed by microglia depletion in the male but not female RKO hippocampus. In contrast, male RKO mice showed greater alterations in microglial morphology and phagocytic activity than females. In both sexes, microglia depletion reduced microglial branching and decreased CD68 production without altering astrogliosis. Taken together, we show that male and female RKO mice exhibit unique perturbations to the neuroimmune system, but microglia depletion is effective at rescuing aspects of behavioral changes in both sexes. These results demonstrate that microglia are involved in Rev-erbα-mediated changes in behavior and neuroinflammation.

How predictive is peer review for gauging impact? The association between reviewer rating scores, publication status, and article impact measured by citations in a pain subspecialty journal.

BACKGROUND: Peer review represents a cornerstone of the scientific process, yet few studies have evaluated its association with scientific impact. The objective of this study is to assess the association of peer review scores with measures of impact for manuscripts submitted and ultimately published. METHODS: 3173 manuscripts submitted to Regional Anesthesia & Pain Medicine (RAPM) between August 2018 and October 2021 were analyzed, with those containing an abstract included. Articles were categorized by topic, type, acceptance status, author demographics and open-access status. Articles were scored based on means for the initial peer review where each reviewer's recommendation was assigned a number: 5 for 'accept', 3 for 'minor revision', 2 for 'major revision' and 0 for 'reject'. Articles were further classified by whether any reviewers recommended 'reject'. Rejected articles were analyzed to determine whether they were subsequently published in an indexed journal, and their citations were compared with those of accepted articles when the impact factor was <1.4 points lower than RAPM's 5.1 impact factor. The main outcome measure was the number of Clarivate citations within 2 years from publication. Secondary outcome measures were Google Scholar citations within 2 years and Altmetric score. RESULTS: 422 articles met inclusion criteria for analysis. There was no significant correlation between the number of Clarivate 2-year review citations and reviewer rating score (r=0.038, p=0.47), Google Scholar citations (r=0.053, p=0.31) or Altmetric score (p=0.38). There was no significant difference in 2-year Clarivate citations between accepted (median (IQR) 5 (2-10)) and rejected manuscripts published in journals with impact factors >3.7 (median 5 (2-7); p=0.39). Altmetric score was significantly higher for RAPM-published papers compared with RAPM-rejected ones (median 10 (5-17) vs 1 (0-2); p<0.001). CONCLUSIONS: Peer review rating scores were not associated with citations, though the impact of peer review on quality and association with other metrics remains unclear.

Chronic circadian phase advance in male mice induces depressive-like responses and suppresses neuroimmune activation.

Altered working and sleeping schedules during the COVID-19 pandemic likely impact our circadian systems. At the molecular level, clock genes form feedback inhibition loops that control 24-hr oscillations throughout the body. Importantly, core clock genes also regulate microglia, the brain resident immune cell, suggesting circadian regulation of neuroimmune function. To assess whether circadian disruption induces neuroimmune and associated behavioral changes, we mimicked chronic jetlag with a chronic phase advance (CPA) model. 32 adult male C57BL/6J mice underwent 6-hr light phase advance shifts every 3 light/dark cycles (CPA) 14 times or were maintained in standard light/dark cycles (control). CPA mice showed higher behavioral despair but not anhedonia in forced swim and sucrose preferences tests, respectively. Changes in behavior were accompanied by altered hippocampal circadian genes in CPA mice. Further, CPA suppressed expression of brain-derived neurotrophic factor (BDNF) and pro-inflammatory cytokine interleukin-1 beta in the hippocampus. Plasma corticosterone concentrations were elevated by CPA, suggesting that CPA may suppress neuroimmune pathways via glucocorticoids. These results demonstrate that chronic circadian disruption alters mood and neuroimmune function, which may have implications for shift working populations such as frontline health workers.

Light at night during development in mice has modest effects on adulthood behavior and neuroimmune activation.

Exposure to light at night (LAN) can disrupt the circadian system, thereby altering neuroimmune reactivity and related behavior. Increased exposure to LAN affects people of all ages - and could have particularly detrimental effects during early-life and adolescence. Despite this, most research on the behavioral and physiological effects of LAN has been conducted in adult animals. Here we evaluated the effects of dim LAN during critical developmental windows on adulthood neuroimmune function and affective/sickness behaviors. Male and female C57BL/6 J mice were exposed to dim LAN [12:12 light (150 lx)/dim (15 lx) cycle] during early life (PND10-24) or adolescence (PND30-44) [control: 12:12 light (150 lx)/dark (0 lx) cycle]. Behaviors were assessed during juvenile (PND 42-44) and adult (PND60) periods. Contrary to our hypothesis, juvenile mice that were exposed to dim LAN did not exhibit changes in anxiety- or depressive-like behaviors. By adulthood, adolescent LAN-exposed female mice showed a modest anxiety-like phenotype in one behavioral task but not another. Adolescent LAN exposure also induced depressive-like behavior in a forced swim task in adulthood in both male and female mice. Additionally, developmental LAN exacerbated the hippocampal cytokine response (IL-1ß) following peripheral LPS in female, but not male mice. These results suggest female mice may be more susceptible to developmental LAN than male mice: LAN female mice had a modest anxiety-like phenotype in adulthood, and upon LPS challenge, higher hippocampal IL-1ß expression. Taken together, developmental LAN exposure in mice promotes a modest increase in susceptibility to anxiety- and depressive-like symptoms.