Preoperative Chronic and Acute Pain Affects Postoperative Cognitive Function Mediated by Neurotransmitters

Postoperative analgesia with morphine promoting microglial activation and neuroinflammation induced by surgery aggravates perioperative neurocognitive dysfunction in aged mice

Introduction

Perioperative neurocognitive dysfunction (PND) is a significant challenge for patients who need surgery worldwide. Morphine can trigger an intense inflammatory reaction in the central nervous system (CNS) at the same time as analgesia, thus adverse effects aggravating PND. Microglia polarization is closely involved in the regulation of neuroinflammation and the TLR4/MyD88/NF-κB signaling pathway. However, the mechanisms of morphine analgesia aggravating PND impairment remain unclear.

Methods

Tibial fracture surgery was performed in 18 months old male C57BL/6 J mice to mimic human orthopedic surgery and postoperative analgesia with morphine hypodermic or ropivacaine. Levels of inflammatory factors in the hippocampus, activation, and phenotype of microglia, an essential protein of TLR4/MyD88/NF-κB signal pathway, synaptic plasticity, and hippocampal-dependent memory function were evaluated after surgery and postoperative analgesia.

Results

Morphine postoperative analgesia increased the expression of pro-inflammatory cytokines IL-1 β, IL-6, and TNF-α, decreased the level of anti-inflammatory IL-10, aggravated the activation of microglia and the destruction of synaptic plasticity in the hippocampus, resulting in hippocampal neuron loss, a significant decrease in the number of synapses and cognitive impairment in aged mice. In addition, the aggravation of neuroinflammatory response and the activation of microglia may be mediated by TLR4/MyD88/NF- κ B signal pathway.

Conclusion

Our results demonstrate that morphine postoperative analgesia may aggravate microglia activation and neuroinflammation in the hippocampus by regulating the TLR4/MyD88/NF- κ B signal pathway and inhibiting the synaptic plasticity hippocampal neurons. It aggravated the acute cognitive decline and cognitive impairment after tibial fracture in elderly mice.

Preoperative inflammatory pain exacerbates postoperative pain and neurocognitive impairment

Aims

Many studies have shown that postoperative pain aggravates perioperative neurocognitive disorder (PND). In this study we aimed to clarify the effect of preoperative inflammatory pain on postoperative pain and cognitive function.

Methods

We established the inflammatory pain model by injected complete freund adjuvant (CFA) and the PND model by tibial fracture surgery in 14- month-old C57BL/6 mice. The paw withdrawal threshold and body weight of the mice were measured 7 days before surgery and 3 days after surgery. On the third postoperative day, mice were subjected to behavioral testing or sacrificed to collect brain tissue.

Results

The result shows that CFA exacerbated postoperative pain and cognitive dysfunction in mice, enhanced surgery-induced activation of microglia and astrocytes in the hippocampus, and increased surgery-induced the overexpression of IL-1β, IL-6, and TNF-α, as well as aggravated the decreased expression of α7nAChR and the overexpression of HMGB1 in the hippocampus induced by surgery.

Conclusion

Our study shows that preoperative inflammatory pain further aggravates postoperative pain and neurocognitive dysfunction in aged rats, and the mechanism may be related to neuroinflammation caused by α7nAChR-mediated CAP dysfunction and high release of HMGB1.

Basic research on postoperative cognitive dysfunction in the past decade: a bibliometric analysis

Objective

Postoperative cognitive dysfunction (POCD) is a prevalent complication following anesthesia and surgery that particularly affects elderly patients, and poses significant health risks. In recent years, there has been an increase in basic research on POCD, with a particular focus on its molecular mechanisms, which have become a prominent area of inquiry. However, no bibliometric analysis has been conducted in this field. This study aims to employ bibliometric methods to comprehensively summarize the current status and developmental trends of basic research on POCD, providing new ideas and strategies for future scientific investigations.

Methods

Relevant literature published between January 1, 2014, and October 30, 2024, was retrieved from the Web of Science Core Collection. Eligible articles were exported in plain text format. The annual output of published papers and data on authors, countries/institutions, journals, keywords, co-cited journals, and co-cited literature were analyzed and visualized using Microsoft Excel, VOSviewer, and CiteSpace software.

Results

A total of 479 papers from 13 countries were included, with a noticeable upward trend in publications over the past decade, particularly in the last 3 years. A total of 105 core authors published four or more papers, with Professor Zuozhiyi identified as the leading contributor. "The Journal of Neuroinflammation" emerged as the most prolific publication source, while Chinese scholars accounted for the highest number of contributions and Dutch scholars led in citations per article. The University of Virginia was the leading institution for publications. Analysis of research hotspots revealed "neuroinflammation," "surgery," "impairment," "memory," and "information" as frequently occurring keywords. Notably, "pyroptosis" was identified as a current research hotspot and "synaptic plasticity" as a rapidly emerging term. The top five cited journals were all ranked as Q1 journals, with "Anesthesiology" being the most cited. Within co-cited articles, the "hippocampal CA1 region" represented the largest cluster, and literature on "neuroinflammation" was a key reference in current discussions.

Conclusion

Over the past decade, basic research on POCD has steadily increased, particularly among Chinese scholars. Bibliometric analysis revealed that the molecular mechanisms underlying POCD are likely crucial focuses of current and future research. This field holds significant potential for further development.

Effect of Painful Stimuli on PVNCRH Neurons: Implications for States of Consciousness Under Isoflurane Anesthesia

BACKGROUND

Many patients undergoing surgery experience accompanying pain symptoms preoperatively. The impact of painful stimuli on general anesthesia remains largely unknown. Corticotrophin-releasing hormone neurons in the paraventricular nucleus of the hypothalamus (PVNCRH neurons) are crucial central stress hubs that respond to painful stimuli. These neurons also participate in regulating processes such as sleep and anesthesia. Natural reward can inhibit PVNCRH neurons to relieve stress-induced behavioral changes, but the effect of natural reward on the anesthesia process in patients with pain is not clear. In this study, we assessed the impact of painful stimuli on isoflurane anesthesia and its potential neural mechanism. We also investigated the potential of natural reward therapy for alleviating the impact of painful stimuli on isoflurane anesthesia.

METHODS

The righting reflex test and cortical electroencephalography (EEG) were used as measures of consciousness in complete Freund's adjuvant (CFA)-injected mice during isoflurane anesthesia. EEG and burst-suppression ratios (BSR) were used to assess the depth of anesthesia. The expression of c-Fos, fiber photometry recording, and brain slice electrophysiology were used to determine neuronal activity changes in PVNCRH neurons after CFA injection or 10% sucrose treatment. Finally, chemogenetic technology was used to specifically manipulate PVNCRH neurons.

RESULTS

Compared to the saline-injected mice, the CFA-injected mice exhibited an increased the mean[SD] induction time of isoflurane anesthesia (354[48] s vs 258[30] s, P = .0001) and a reduced BSR of isoflurane anesthesia (60.1[10.3] % vs 81.5[9.76] %, P = .002). CFA injection increased PVN c-Fos expression (3667[706] vs 1735[407], P = .0002) and enhanced the population activity of PVNCRH neurons (33.4[13.6] % vs 1.23[3.57] %, P = .0009). Chemogenetic suppression of PVNCRH neurons reversed the anesthesia abnormalities in CFA-injected mice. Natural reward accelerated the induction time of isoflurane anesthesia (252[24] s vs 324[36] s, P = .003) and increased the BSR of isoflurane anesthesia (84.8[5.36] % vs 57.7[14.3] %, P = .0005). Chemogenetic activation of PVNCRH neurons reversed the effect of natural reward on isoflurane anesthesia in CFA-injected mice.

CONCLUSIONS

Painful stimuli affect the process of isoflurane anesthesia by activating PVNCRH neurons, which implies that these neurons modulate isoflurane anesthesia. Additionally, natural reward alleviates the impact of painful stimuli on isoflurane anesthesia by inhibiting PVNCRH neurons.

The Role of the Intestinal Flora and Its Derivatives in Neurocognitive Disorders: A Narrative Review from Surgical Perspective

Perioperative neurocognitive dysfunction is a significant concern for population health, impacting postoperative recovery and increasing the financial burden on patients. With an increasing number of surgical procedures being performed, the prevention and management of perioperative neurocognitive dysfunction have garnered significant attention. While factors such as age, lifestyle, genetics, and education are known to influence the development of cognitive dysfunction, recent research has highlighted the role of the gut microbiota in neurological health. An increased abundance of pro-inflammatory gut microbiota can trigger and worsen neuroinflammation, neuronal cell damage, and impaired cellular autophagy. Moreover, the inflammation-promoting gut microbiota can disrupt immune function, impair neuroautophagy, and affect the production and circulation of extracellular vesicles and neurotransmitters. These factors collectively play a role in the onset and advancement of cognitive impairment. This narrative review delves into the molecular mechanisms through which gut microbiota and their derivatives contribute to cognitive impairment, focusing on the impact of anesthesia surgery, changes in gut microbial populations, and perioperative cognitive impairment associations. The study suggests that alterations in the abundance of various bacterial species and their metabolites pre- and post-surgery may be linked to postoperative cognitive impairment. Furthermore, the potential of probiotics or prebiotics in addressing cognitive impairment is discussed, offering a promising avenue for investigating the treatment of perioperative neurocognitive disorders.

Chronic Pain-Related Cognitive Deficits: Preclinical Insights into Molecular, Cellular, and Circuit Mechanisms

Cognitive impairment is a common comorbidity of chronic pain, significantly disrupting patients' quality of life. Despite this comorbidity being clinically recognized, the underlying neuropathological mechanisms remain unclear. Recent preclinical studies have focused on the fundamental mechanisms underlying the coexistence of chronic pain and cognitive decline. Pain chronification is accompanied by structural and functional changes in the neural substrate of cognition. Based on the developments in electrophysiology and optogenetics/chemogenetics, we summarized the relevant neural circuits involved in pain-induced cognitive impairment, as well as changes in connectivity and function in brain regions. We then present the cellular and molecular alternations related to pain-induced cognitive impairment in preclinical studies, mainly including modifications in neuronal excitability and structure, synaptic plasticity, glial cells and cytokines, neurotransmitters and other neurochemicals, and the gut-brain axis. Finally, we also discussed the potential treatment strategies and future research directions.

Cognitive dysfunction in older patients undergoing non-neurosurgery in the immediate postoperative period: A systematic review

AIM

To explore the risk factors associated with postoperative cognitive dysfunction in older patients within the first 7 days after non-neurosurgical surgery and anaesthesia.

DESIGN

A systematic review.

METHODS

Following, PRISMA 2020 (Preferred Reporting Items for Systematic Reviews and Meta-analyses). Checklist, a systematic review of studies published from January 2018 to January 2024. The literature search was conducted across six electronic online databases, including PubMed, EMBASE, Scopus, Ovid, MEDLINE and Science Direct, and the Johns Hopkins Nursing Evidence-Based Practice Evidence Rating Scale was used for study appraisal.

RESULTS

The initial search yielded 1750 studies. The review included 19 studies which comprised prospective observational, case-control and retrospective studies. The prevalence of postoperative cognitive dysfunction ranged from 19% to 64% among older adults undergoing non-neurosurgery. The identified risk factors were classified into three phases including preoperative, intraoperative and postoperative. Preoperative risk factors were found in age, educational attainment, malnutrition, preoperative biomarkers and co-morbidities. Intraoperative risk factors were the duration of the operation, blood loss during the operation and anaesthesia used. Postoperative risk factors consisted of postoperative biomarkers and postoperative pain.

PATIENT OR PUBLIC CONTRIBUTION

The result from this review may assist researchers and healthcare providers in assessing the underlying causes and risk factors of postoperative cognitive dysfunction, and in formulating suitable preventative and therapeutic strategies for older adults with non-neurosurgery during the short-term postoperative period.

Multi-frequency electromagnetic radiation induces anxiety in mice via inflammation in the cerebral cortex

Modern life is filled with radiofrequency electromagnetic radiation (RF-EMR) in various frequency bands, while the health risks are not clear. In this study, mice were whole-body exposed to 0.9/1.5/2.65 GHz radiofrequency radiation at 4 W/kg for 2 h per day for 4 weeks to investigate the emotional effects. It was found that the mice showed anxiety but no severe depression. The ELISA results showed a significant decrease in amino acid neurotransmitters (GABA, DA, 5-HT), although acetylcholine (ACH) levels were not significantly altered. Furthermore, Western blot results showed that BDNF, TrkB, and CREB levels were increased in the cerebral cortex, while NF-κB levels were decreased. In addition, pro-inflammatory factors (IL-6, IL-1β, TNF-α) were significantly elevated, and anti-inflammatory factors (IL-4, IL-10) tended to decrease. In conclusion, multi-frequency electromagnetic radiation induces an inflammatory response through the CREB-BDNF-TrkB and NF-κB pathways in the cerebral cortex and causes a decrease in excitatory neurotransmitters, which ultimately causes anxiety in mice.

Upconversion-Mediated Optogenetics for the Treatment of Surgery-Induced Postoperative Neurocognitive Dysfunction

Perioperative neurocognitive disorder (PND) is a common complication in surgical patients. While many interventions to prevent PND have been studied, the availability of treatment methods is limited. Thus, it is crucial to delve into the mechanisms of PND, pinpoint therapeutic targets, and develop effective treatment approaches. In this study, reduced dorsal tenia tecta (DTT) neuronal activity was found to be associated with tibial fracture surgery-induced PND, indicating that a neuronal excitation-inhibition (E-I) imbalance could contribute to PND. Optogenetics in the DTT brain region was conducted using upconversion nanoparticles (UCNPs) with the ability to convert 808 nm near-infrared light to visible wavelengths, which triggered the activation of excitatory neurons with minimal damage in the DTT brain region, thus improving cognitive impairment symptoms in the PND model. Moreover, this noninvasive intervention to modulate E-I imbalance showed a positive influence on mouse behavior in the Morris water maze test, which demonstrates that UCNP-mediated optogenetics is a promising tool for the treatment of neurological imbalance disorders.

Activation of LXRs alleviates neuropathic pain-induced cognitive dysfunction by modulation of microglia polarization and synaptic plasticity via PI3K/AKT pathway

OBJECTIVE

Cognitive dysfunction is a common comorbidity in patients with chronic pain. Activation of Liver X receptors (LXRs) plays a potential role in improving cognitive disorders in central nervous diseases. In this study, we investigated the role of LXRs in cognitive deficits induced by neuropathic pain.

METHODS

We established the spared nerve injury (SNI) model to investigate pain-induced memory dysfunction. Pharmacological activation of LXRs with T0901317 or inhibition with GSK2033 was applied. PI3K inhibitor LY294002 was administered to explore the underlying mechanism of LXRs. Changes in neuroinflammation, microglia polarization, and synaptic plasticity were assessed using biochemical technologies.

RESULTS

We found that SNI-induced cognitive impairment was associated with reduced LXRβ expression, increased M1-phenotype microglia, decreased synaptic proteins, and inhibition of PI3K/AKT signaling pathway in the hippocampus. Activation of LXRs using T0901317 effectively alleviated SNI-induced cognitive impairment. Additionally, T0901317 promoted the polarization of microglia from M1 to M2, reduced pro-inflammatory cytokines, and upregulated synaptic proteins in the hippocampus. However, administration of GSK2033 or LY294002 abolished these protective effects of T0901317 in SNI mice.

CONCLUSIONS

LXRs activation alleviates neuropathic pain-induced cognitive impairment by modulating microglia polarization, neuroinflammation, and synaptic plasticity, at least partly via activation of PI3K/AKT signaling in the hippocampus. LXRs may be promising targets for addressing pain-related cognitive deficits.

Postoperative cognitive dysfunction-current research progress

Postoperative cognitive dysfunction (POCD) commonly occurs after surgery, particularly in elderly individuals. It is characterized by a notable decline in cognitive performance, encompassing memory, attention, coordination, orientation, verbal fluency, and executive function. This reduction in cognitive abilities contributes to extended hospital stays and heightened mortality. The prevalence of POCD can reach 40% within 1 week following cardiovascular surgery and remains as high as 17% 3 months post-surgery. Furthermore, POCD exacerbates the long-term risk of Alzheimer's disease (AD). As a result, numerous studies have been conducted to investigate the molecular mechanisms underlying POCD and potential preventive strategies. This article provides a review of the research progress on POCD.

Neuropsychological Symptoms and Functional Capacity in Older Adults with Chronic Pain

The impact of chronic pain on neuropsychological functioning of older adults is under-studied. The present study examined the relationship between chronic pain, depression, anxiety, cognition, and functional capacity in community-dwelling older adults (ages 60-89) who completed an outpatient neuropsychological evaluation (N = 452). Psychometrically sound and validated measures were used to assess depression (Geriatric Depression Scale [GDS]), anxiety (Beck Anxiety Inventory [BAI]), cognitive functioning (the Mini Mental Status Exam [MMSE] and the Repeatable Battery for the Assessment of Neuropsychological Status [RBANS]), and functional capacity (Texas Functional Living Scale [TFLS] and Instrumental Activities of Daily Living Questionnaire [IADL]). Multivariate analyses of covariance (MANCOVA) were conducted to examine differences between individuals with and without chronic pain, adjusting for age, education, gender, marital status, and other medical conditions. Results indicated that participants endorsing chronic pain displayed significantly higher levels of depression and anxiety, as well as lower levels of cognitive functioning and functional capacity, than those without chronic pain. Additionally, results of hierarchical multiple regressions indicated that chronic pain explained unique variance in all outcome variables, beyond demographic characteristics and health status. Chronic pain management may be an important intervention target for clinicians to help address cognitive and psychological functioning in older adults.

Neuroinflammation: The central enabler of postoperative cognitive dysfunction

The proportion of advanced age patients undergoing surgical procedures is on the rise owing to advancements in surgical and anesthesia technologies as well as an overall aging population. As a complication of anesthesia and surgery, older patients frequently suffer from postoperative cognitive dysfunction (POCD), which may persist for weeks, months or even longer. POCD is a complex pathological process involving multiple pathogenic factors, and its mechanism is yet unclear. Potential theories include inflammation, deposition of pathogenic proteins, imbalance of neurotransmitters, and chronic stress. The identification, prevention, and treatment of POCD are still in the exploratory stages owing to the absence of standardized diagnostic criteria. Undoubtedly, comprehending the development of POCD remains crucial in overcoming the illness. Neuroinflammation is the leading hypothesis and a crucial component of the pathological network of POCD and may have complex interactions with other mechanisms. In this review, we discuss the possible ways in which surgery and anesthesia cause neuroinflammation and investigate the connection between neuroinflammation and the development of POCD. Understanding these mechanisms may likely ensure that future treatment options of POCD are more effective.

Postsurgery Subjective Cognitive and Short-Term Memory Impairment Among Middle-Aged Chinese Patients

Importance

Perioperative neurocognitive disorder, particularly postoperative cognitive impairment, is common and associated with multiple medical and social adversities, although data from China are lacking.

Objective

To examine the incidence, trajectory, and risk factors for subjective cognitive and short-term memory impairment after surgery in the Chinese population.

Design, Setting, and Participants

This cohort study used data from the China Surgery and Anesthesia Cohort to assess surgical patients aged 40 to 65 years from 2 medical centers between July 15, 2020, and March 31, 2023, with active follow-up within 1 year after the surgery. Of 11 158 patients who were successfully recruited (response rate, 94.4%), 10 149 participants were eligible and available for analysis. From this population, separate cohorts were constructed for analyzing subjective cognitive impairment (8105 noncardiac and 678 cardiac surgery patients) and short-term memory impairment (5246 noncardiac and 454 cardiac surgery patients).

Exposures

Twenty-four potential risk factors regarding comorbidities, preoperative psychological conditions, anesthesia- or surgery-related factors, and postsurgical events were included.

Main Outcomes and Measures

Outcomes included subjective cognitive function measured by the 8-Item Informant Interview to Differentiate Aging and Dementia (AD8; scores range from 0 to 8, with higher scores indicating more severe cognitive impairment) and short-term memory measured by the 3-Word Recall Test (TRT; scores range from 0 to 3, with lower scores indicating more severe short-term memory impairment) at 1, 3, 6, and 12 months after noncardiac and cardiac surgery. Generalized linear mixed models were used to identify risk factors associated with the presence of AD8 (score ≥2) or TRT (score <3) abnormality as well as the aggressively deteriorative trajectories of those cognitive measurements.

Results

For noncardiac surgery patients, the AD8 analysis included 8105 patients (mean [SD] age, 52.3 [7.1] years; 3378 [41.7%] male), and the TRT analysis included 5246 patients (mean [SD] age, 51.4 [7.0] years; 1969 [37.5%] male). The AD8 abnormality incidence rates after noncardiac surgery increased from 2.2% (175 of 8105) at 7 days to 17.1% (1059 of 6191) at 6 months after surgery, before appearing to decrease. In contrast, the TRT abnormality incidence rates followed a U-shaped pattern, with the most pronounced incidence rates seen at 7 days (38.9% [2040 of 5246]) and 12 months (49.0% [1394 of 2845]). Similar patterns were seen among cardiac surgery patients for the AD8 analysis (678 patients; mean [SD] age, 53.2 [6.3] years; 393 [58.0%] male) and TRT analysis (454 patients; mean [SD] age, 52.4 [6.4] years; 248 [54.6%] male). Among noncardiac surgery patients, the top risk factors for aggressively deteriorative AD8 trajectory and for AD8 abnormality, respectively, after surgery were preoperative sleep disturbances (Pittsburgh Sleep Quality Index ≥16 vs 0-5: odds ratios [ORs], 4.04 [95% CI, 2.20-7.40] and 4.54 [95% CI, 2.40-8.59]), intensive care unit stay of 2 days or longer (ORs, 2.43 [95% CI, 1.26-4.67] and 3.07 [95% CI, 1.67-5.65]), and preoperative depressive symptoms (ORs, 1.76 [95% CI, 1.38-2.24] and 2.23 [95% CI, 1.79-2.77]). Analyses for TRT abnormality and trajectory, as well as the analyses conducted among cardiac surgery patients, found fewer associated factors.

Conclusions and Relevance

This cohort study of middle-aged Chinese surgery patients found subjective cognitive and short-term memory impairment within 12 months after both cardiac and noncardiac surgery, with multiple identified risk factors, underscoring the potential of preoperative psychological interventions and optimized perioperative management for postoperative cognitive impairment prevention.

Effect of transcutaneous electrical acupoint stimulation on postoperative cognitive function in older patients with lung cancer: A randomized, double-blind, placebo-controlled trial

Objective

This trial was to examine the effect of transcutaneous electrical acupoint stimulation (TEAS) on postoperative cognitive function in older patients who underwent thoracoscopic pulmonary resection.

Methods

This was a prospective, randomized, double-blind, placebo-controlled study. 128 patients scheduled for surgery were randomly assigned to the TEAS group and sham-TEAS group. A standardized intervention of TEAS or sham-TEAS on the acupoints of Baihui (DU20) and bilateral Neiguan (PC6), Hegu (LI4), and Zusanli (ST36) from 30 min before anesthesia induction until the end of the surgery, combined with a general anesthetic protocol performed in the two groups respectively. The primary outcome was the incidence of postoperative cognitive dysfunction (POCD) assessed via the Montreal Cognitive Assessment (MoCA) scale at each time point. The secondary outcomes included the results of the Mini-Mental State Examination (MMSE) score, the Numerical Rating Scale (NRS) on pain and sleep, the European Organization for Research and Treatment of Cancer Quality of Life (EORTC-QLQ-C30), and a chronic pain questionnaire at relative time points.

Results

Participants who completed the 12-month trial of the two groups were well-matched in baseline demographic and clinical parameters. At postoperative day 1, day 7, and day 30 time points, the incidence of POCD in the sham-TEAS group was always significantly higher than in the TEAS group (65.4% vs 20%, 43.6% vs 7.3%, 40% vs 3.6%, all P < 0.001). Also, the TEAS group showed better scores of MMSE, sleep, and pain compared with the sham-TEAS group (all P < 0.001). At 6 and 12 months points, the global health scores of the TEAS group were still significantly higher than the sham-TEAS group, and the prevalence of chronic pain was significantly lower than the sham-TEAS group (all P < 0.05).

Conclusion

TEAS could effectively improve the postoperative cognitive function and long-term life quality of geriatric patients with lung cancer.

Modulation of the Inflammatory Response by Pre-emptive Administration of IMT504 Reduces Postoperative Pain in Rats and has Opioid-Sparing Effects

Despite the available knowledge on underlying mechanisms and the development of several therapeutic strategies, optimal management of postoperative pain remains challenging. This preclinical study hypothesizes that, by promoting an anti-inflammatory scenario, pre-emptive administration of IMT504, a noncoding, non-CpG oligodeoxynucleotide with immune modulating properties, will reduce postincisional pain, also facilitating therapeutic opioid-sparing. Male adult Sprague-Dawley rats with unilateral hindpaw skin-muscle incision received pre-emptive (48 and 24 hours prior to surgery) or postoperative (6 hours after surgery) subcutaneous vehicle (saline) or IMT504. Various groups of rats were prepared for pain-like behavior analyses, including subgroups receiving morphine or naloxone, as well as for flow-cytometry or quantitative RT-PCR analyses of the spleen and hindpaws (for analysis of inflammatory phenotype). Compared to vehicle-treated rats, pre-emptive IMT504 significantly reduced mechanical allodynia by 6 hours after surgery, and accelerated recovery of basal responses from 72 hours after surgery and onwards. Cold allodynia was also reduced by IMT504. Postoperative administration of IMT504 resulted in similar positive effects on pain-like behavior. In IMT504-treated rats, 3 mg/kg morphine resulted in comparable blockade of mechanical allodynia as observed in vehicle-treated rats receiving 10 mg/kg morphine. IMT504 significantly increased hindpaw infiltration of mesenchymal stem cells, CD4+T and B cells, and caused upregulated or downregulated transcript expressions of interleukin-10 and interleukin-1β, respectively. Also, IMT504 treatment targeted the spleen, with upregulated or downregulated transcript expressions, 6 hours after incision, of interleukin-10 and interleukin-1β, respectively. Altogether, pre-emptive or postoperative IMT504 provides protection against postincisional pain, through participation of significant immunomodulatory actions, and exhibiting opioid-sparing effects. PERSPECTIVE: This preclinical study introduces the noncoding non-CpG oligodeoxynucleotide IMT504 as a novel modulator of postoperative pain and underlying inflammatory events. The opioid-sparing effects observed for IMT504 appear as a key feature that could contribute, in the future, to reducing opioid-related adverse events in patients undergoing surgical intervention.

No association of postoperative opioid usage with long-term surgery outcomes in patients with liver cancer: a population-based retrospective cohort study

ABSTRACT

Hepatocellular carcinoma (HCC) is a fatal cancer worldwide, and surgical resection remains the standard treatment. Postoperative opioid prescription has been believed to affect cancer recurrence through complex biological pathways. We conducted a retrospective cohort study using the Longitudinal Health Insurance Database of Taiwan to evaluate the relationship between postoperative opioid use and long-term surgical outcomes of patients with HCC. This study had a retrospective cohort design. In total, 812 patients older than 20 years who underwent hepatectomy because of HCC were included. The exposure group comprised patients who used opioids during hospitalization postoperatively. The comparison group included those who never used opioids during hospitalization postoperatively. A Cox proportional hazards model was used to evaluate the overall survival or recurrence-free survival rate between the opioid group and the nonopioid group. A total of 530 patients received opioids postoperatively and 282 patients did not. The hazard ratios of overall survival and recurrence-free survival were 1.10 (95% confidence interval [CI], 0.85-1.41) and 1.15 (95% CI, 0.91-1.46), respectively. Total postoperative opioids were converted into oral morphine milligram equivalents and then divided into 3 equal subgroups: low dose, <40 mg; medium dose, 40 to 144 mg; and high dose, ≥145 mg. The hazard ratios of overall survival were 0.88 (95% CI, 0.63-1.24) for the low-dose group, 1.27 (95% CI, 0.92-1.74) for the medium-dose group, and 1.14 (95% CI, 0.83-1.58) for the high-dose group. Postoperative opioids do not affect overall and recurrence-free survival in patients undergoing hepatectomy or liver transplantation because of HCC. Cancer recurrence should not be a clinical concern regarding postoperative opioid prescription.

Sex differences in chronic pain-induced mental disorders: Mechanisms of cerebral circuitry

Mental disorders such as anxiety and depression induced by chronic pain are common in clinical practice, and there are significant sex differences in their epidemiology. However, the circuit mechanism of this difference has not been fully studied, as preclinical studies have traditionally excluded female rodents. Recently, this oversight has begun to be resolved and studies including male and female rodents are revealing sex differences in the neurobiological processes behind mental disorder features. This paper reviews the structural functions involved in the injury perception circuit and advanced emotional cortex circuit. In addition, we also summarize the latest breakthroughs and insights into sex differences in neuromodulation through endogenous dopamine, 5-hydroxytryptamine, GABAergic inhibition, norepinephrine, and peptide pathways like oxytocin, as well as their receptors. By comparing sex differences, we hope to identify new therapeutic targets to offer safer and more effective treatments.

Fascia iliaca compartment block can reduce the incidence of early post-operative cognitive impairment in elderly patients with high-risk hip replacement

Objective

In this study, we aimed to observe the effects of ultrasound-guided fascia iliaca compartment block (FICB) combined with hypobaric spinal anesthesia on post-operative pain and cognitive function in elderly patients with high-risk hip replacement.

Methods

A total of 84 elderly patients-aged 65-85 years, with American Society of Anesthesiologists physical status III-IV, and scheduled for hip arthroplasty between September 2021 and May 2022-were selected. One or more organs with moderate to severe impairment were included in all patients. The patients were randomly divided into a hypobaric spinal anesthesia group (group C, control group) and an ultrasound-guided FICB combined with hypobaric spinal anesthesia group (group E, experimental group). Group C was given 3.5 mL of 0.32% ropivacaine hypobaric spinal anesthesia, and group E received ultrasound-guided FICB combined with 3.5 mL of 0.32% ropivacaine hypobaric spinal anesthesia. The patients were compared using the visual analog scale (VAS) for pain, Harris hip function score, and simple Mini-Mental State Examination (MMSE) scale. Blood β-amyloid (Aβ) and neuronal microtubule-associated protein (tau) levels were measured. We compared intraoperative conditions and post-operative complications between the two groups to assess the effects of FICB combined with hypobaric spinal anesthesia on post-operative pain and cognitive function in elderly patients with high-risk hip replacement.

Results

At 1 and 3 days after the operation, patients in group C had significantly higher VAS and lower MMES scores than those in group E. The differences were statistically significant at 1 (P < 0.01) and 3 (P < 0.05) days after the operation. At 1 day after operation, the Harris score of patients in group C was significantly lower than that of patients in group E (P < 0.05). The Aβ and tau levels of patients in group C were significantly higher than those of patients in group E at 1 day after the operation (P < 0.01). The Aβ levels of patients in group C were significantly higher than those of patients in group E at 3 days after the operation (P < 0.05). The intraoperative conditions and post-operative complication rates did not differ significantly between the two groups. At 1 day before and 5 days after the operation, there was no difference in any of the indicators.

Conclusion

By lowering pain and managing Aβ and tau protein concentrations, FICB can successfully lower the incidence of early post-operative cognitive impairment in elderly patients with high-risk hip replacement.

Clinical trial registration

www.chictr.org.cn, identifier: ChiCTR2100051162.

Early Cognitive Dysfunction in Elderly Patients after Total Knee Arthroplasty: An Analysis of Risk Factors and Cognitive Functional Levels

Background

Cognitive dysfunction after total knee arthroplasty (TKA) is very common in elderly patients. Postoperative cognitive dysfunction (POCD), as a form of cognitive dysfunction, may affect patients' short- and long-term recoveries. The identification of meaningful risk factors may help reduce the occurrence of POCD in the future.

Objective

Our goal was to retrospectively investigate the risk factors for early POCD in elderly patients undergoing TKA and to further analyze the relationship between the intensity of risk factors and the level of cognitive function.

Methods

The related indicators and the Montreal Cognitive Function Assessment Scale (MOCA) scores of 105 elderly patients were collected by searching the electronic case system. According to the postoperative MOCA score, patients were divided into three groups: normal group (group N), mild POCD group (group M), and severe POCD group (group S). SPSS 25.0 software was used for statistical analyses.

Results

At baseline, the preoperative MOCA score was significantly different in patients with POCD (P ≤ 0.001), while other baseline indicators were not significantly different. In terms of changes in hemoglobin levels, statistically significant differences were observed between group M, group S, and group N (P = 0.039). Among inflammatory indicators, only postoperative CRP levels showed a statistically significant difference in patients with POCD (P = 0.041). Postoperative pain was also significantly different among the three groups (P = 0.009). The multivariate regression analysis revealed that a low preoperative MOCA score and severe postoperative pain were independent risk factors for mild and severe cognitive impairment, while a high postoperative CRP level was only an independent risk factor for mild cognitive impairment.

Conclusions

Our study found that the level of preoperative cognitive function, postoperative CRP level, and postoperative pain were independent risk factors for POCD. Moreover, the levels of preoperative cognitive function and postoperative pain were more strongly correlated with severe POCD than postoperative CRP levels.

Update on the Mechanism and Treatment of Sevoflurane-Induced Postoperative Cognitive Dysfunction

Sevoflurane is one of the most widely used anesthetics for the induction and maintenance of general anesthesia in surgical patients. Sevoflurane treatment may increase the incidence of postoperative cognitive dysfunction (POCD), and patients with POCD exhibit lower cognitive abilities than before the operation. POCD affects the lives of patients and places an additional burden on patients and their families. Understanding the mechanism of sevoflurane-induced POCD may improve prevention and treatment of POCD. In this paper, we review the diagnosis of POCD, introduce animal models of POCD in clinical research, analyze the possible mechanisms of sevoflurane-induced POCD, and summarize advances in treatment for this condition.

TNF-α - mediated peripheral and central inflammation are associated with increased incidence of PND in acute postoperative pain

Background

Acute postoperative pain plays an important role in the perioperative neurocognitive disorders (PND). The pathogenesis of PND is still unknown, but it is generally believed that peripheral and central nervous system inflammation play an important role, and acute postoperative pain is also thought to aggravate postoperative inflammatory response. The aim of the present study is to explore the effect of acute postoperative pain on peripheral and central nervous system inflammation and related cognitive impairment behaviour in elderly rats after surgery.

Methods

Rats were assigned into four groups: control, surgery for internal fixation for tibial fracture, surgery with analgesia using intraperitoneal morphine, and morphine without surgery. Pain was assessed by the Subjective Pain Scale. The spatial memory of rats was assessed by the Morris water maze (delayed matching task) from the second day to the seventh day after surgery (POD2-POD7). In part of the rats, the pro-inflammatory cytokines TNF-α in plasma, the medial prefrontal cortex (mPFC), and the hippocampus were determined by ELISA on the POD2. The activation of microglia and the expression of c-Fos in the hippocampal CA1 regions and mPFC were detected by the immunohistochemical method on the POD2.

Results

Acute postoperative pain and spatial memory impairment occurred after operation, and postoperative analgesia could significantly improve the both parameters. Additionally, on the POD2, the levels of TNF-α in plasma, hippocampus and mPFC were significantly increased, while the activation of microglia cells and the expression c-Fos in the hippocampal CA1 regions and mPFC were significantly increased. And postoperative analgesia with morphine significantly inhibited the above reactions.

Conclusion

Our data suggest that acute postoperative pain increases the incidence of perioperative neurocognitive disorders. Peripheral and central nervous system inflammation may be involved in this cognitive impairment. And reducing the intensity of acute postoperative pain may be one of the main preventive strategies for PND.