The Role of Cytokines in Acute and Chronic Postsurgical Pain in Pediatric Patients after Major Musculoskeletal Surgeries

Study Objective

To determine if baseline cytokines and their changes over postoperative days 0-2 (POD0-2) predict acute and chronic postsurgical pain (CPSP) after major surgery.

Design

Prospective, observational, longitudinal nested study.

Setting

University-affiliated quaternary children's hospital.

Patients

Subjects (≥8 years old) with idiopathic scoliosis undergoing spine fusion or pectus excavatum undergoing Nuss procedure.

Measurements

Demographics, surgical, psychosocial measures, pain scores, and opioid use over POD0-2 were collected. Cytokine concentrations were analyzed in serial blood samples collected before and after (up to two weeks) surgery, using Luminex bead arrays. After data preparation, relationships between pre- and post-surgical cytokine concentrations with acute (% time in moderate-severe pain over POD0-2) and chronic (pain score>3/10 beyond 3 months post-surgery) pain were analyzed. After adjusting for covariates, univariate/multivariate regression analyses were conducted to associate baseline cytokine concentrations with postoperative pain, and mixed effects models were used to associate longitudinal cytokine concentrations with pain outcomes.

Main Results

Analyses included 3,164 measures of 16 cytokines from 112 subjects (median age 15.3, IQR 13.5-17.0, 54.5% female, 59.8% pectus). Acute postsurgical pain was associated with higher baseline concentrations of GM-CSF (β=0.95, SE 0.31; p=.003), IL-1β (β=0.84, SE 0.36; p=.02), IL-2 (β=0.78, SE 0.34; p=.03), and IL-12 p70 (β=0.88, SE 0.40; p=.03) and longitudinal postoperative elevations in GM-CSF (β=1.38, SE 0.57; p=.03), IFNγ (β=1.36, SE 0.6; p=.03), IL-1β (β=1.25, SE 0.59; p=.03), IL-7 (β=1.65, SE 0.7, p=.02), and IL-12 p70 (β=1.17, SE 0.58; p=.04). In contrast, CPSP was associated with lower baseline concentration of IL-8 (β= -0.39, SE 0.17; p=.02), and the risk of developing CPSP was elevated in patients with lower longitudinal postoperative concentrations of IL-6 (β= -0.57, SE 0.26; p=.03), IL-8 (β= -0.68, SE 0.24; p=.006), and IL-13 (β= -0.48, SE 0.22; p=.03). Furthermore, higher odds for CPSP were found for females (vs. males) for IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, and TNFα, and for pectus (vs. spine) surgery for IL-8 and IL-10.

Conclusion

We identified pro-inflammatory cytokines associated with increased acute postoperative pain and anti-inflammatory cytokines associated with lower CPSP risk, with potential to serve as predictive and prognostic biomarkers.

Efficacy and safety of perioperative ketamine for the prevention of chronic postsurgical pain: A meta-analysis

STUDY OBJECTIVE

Assessment of the efficacy and safety of perioperative intravenous ketamine in reducing incidence and severity of chronic postsurgical pain.

STUDY DESIGN

A systematic review and meta-analysis of randomized controlled trials (RCTs).

DATA SOURCES

The following data sources were systematically searched: MEDLINE, CENTRAL, and EMBASE (till 02/2021).

PATIENTS

Adult patients undergoing any surgery.

INTERVENTIONS

Perioperative use of intravenous ketamine as an additive analgesic drug compared to placebo, no active control treatment, and other additive drugs.

MEASUREMENTS

Primary outcomes were number of patients with chronic postsurgical pain after 6 months and ketamine related adverse effects. Secondary outcomes were chronic postsurgical pain incidence after 3 and 12 months, chronic postsurgical neuropathic pain incidence, chronic postsurgical moderate to severe pain incidence, intensity of chronic postsurgical pain at rest, and during movement, oral morphine consumption after 3, 6, and 12 months and incidence of opioid-related adverse effects.

MAIN RESULTS

Thirty-six RCTs were included with a total of 3572 patients. Ketamine compared to placebo may result in no difference in the number of patients with chronic postsurgical pain after 6 months (risk ratio (RR) 0.86, 95% confidence interval (CI) 0.71-1.05; I2  = 34%; 16 studies; low-certainty evidence). Ketamine may reduce the incidence of chronic postsurgical neuropathic pain after 3 months in comparison to placebo (RR 0.78, 95% CI 0.62-0.99, I2  = 31%, seven trials, low-certainty evidence). Ketamine compared to placebo may increase the risk for postoperative nystagmus (RR 9.04, 95% CI 1.15-70.90, I2 30%, two trials, low-certainty evidence) and postoperative visual disturbances (RR 2.29, 95% CI 1.05-4.99, I2 10%, seven trials, low-certainty evidence).

CONCLUSIONS

There is low-certainty evidence that perioperative ketamine has no effect on chronic postsurgical pain in adult patients. Low-certainty evidence suggests that ketamine compared to placebo may reduce incidence of chronic postsurgical neuropathic pain after 3 months. Questions like ideal dosing, treatment duration and more patient-related outcome measures remain unanswered, which warrants further studies.

PROTOCOL REGISTRATION

Prospero CRD42021223625, 07.01.2021.

Time-Dependent Prediction Models for Individual Prognosis of Chronic Postsurgical Pain following Knee Replacement Based on an Extensive Multivariable Data Set

(1) Background: Clinically useful prediction models for chronic postsurgical pain (CPSP) in knee replacement (TKA) are lacking. (2) Methods: In our prospective, multicenter study, a wide-ranging set of 91 variables was collected from 933 TKA patients at eight time points up to one year after surgery. Based on this extensive data pool, simple and complex prediction models were calculated for the preoperative time point and for 6 months after surgery, using least absolute shrinkage and selection operator (LASSO) 1se and LASSO min, respectively. (3) Results: Using preoperative data only, LASSO 1se selected age, the Revised Life Orientation Test on pessimism, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)-subscore pain and the Timed "Up and Go" Test for prediction, resulting in an area under the curve (AUC) of 0.617 and a Brier score of 0.201, expressing low predictive power only. Using data up to 6 months after surgery, LASSO 1se included preoperative Patient Health Questionnaire-4, Knee Injury and Osteoarthritis Outcome Score (KOOS)-subscore pain (pain) 3 months after surgery (month), WOMAC pain 3 and 6 months, KOOS subscore symptoms 6 months, KOOS subscore sport 6 months and KOOS subscore Quality of Life 6 months. This improved the predictive power to an intermediate one (AUC 0.755, Brier score 0.168). More complex models computed using LASSO min did little to further improve the strength of prediction. (4) Conclusions: Even using multiple variables and complex calculation methods, the possibility of individual prediction of CPSP after TKA remains limited.

Preoperative psychological symptoms and chronic postsurgical pain: analysis of the prospective China Surgery and Anaesthesia Cohort study

BACKGROUND

Both preoperative psychological symptoms and chronic postsurgical pain (CPSP) are prevalent conditions and major concerns among surgery patients, with inconclusive associations.

METHODS

Based on the China Surgery and Anaesthesia Cohort (CSAC), we recruited 8350 surgery patients (40-65 yr old) from two medical centres between July 2020 and March 2023. Patients with preoperative psychological symptoms (i.e. anxiety, depression, stress reaction, and poor sleep quality) were identified using corresponding well-established scales. We then examined the associations of individual preoperative psychological symptoms and major patterns of preoperative psychological symptoms (identified by k-means clustering analysis) with CPSP, and different pain trajectories within 3 months. Lastly, mediation analyses were conducted to elucidate the mediating role of surgery/anaesthesia-related factors and the presence of 1-month postoperative psychological symptoms on the studied associations.

RESULTS

We included 1302 (1302/8350, 15.6%) CPSP patients. When analysed separately, all studied preoperative psychological symptoms were associated with increased CPSP risk, with the most pronounced odds ratio noted for anxiety (1.52, 95% confidence interval [CI] 1.23-1.86). Compared with patients clustered in the minor symptom group, excess risk of CPSP and experiencing an increasing pain trajectory was increased among patients with preoperative psychological symptoms featured by sleep disturbances (odds ratio=1.46, 95% CI 1.25-1.70 for CPSP and 1.58, 95% CI 1.20-2.08 for increasing pain trajectory) and multiple psychological symptoms (1.84 [95% CI 1.48-2.28] and 4.34 [95% CI 3.20-5.88]). Mediation analyses revealed acute/subacute postsurgical pain and psychological symptoms existing 1 month after surgery as notable mediators of the observed associations.

CONCLUSIONS

The presence of preoperative psychological symptoms might individually or jointly increase the risk of chronic postsurgical pain or experiencing deterioration in pain trajectory. Interventions for managing acute/subacute postsurgical pain and psychological symptoms at 1 month after surgery might help reduce such risk.

CLINICAL TRIAL REGISTRATION

ChiCTR2000034039.

Pain during the first year after scoliosis surgery in adolescents, an exploratory, prospective cohort study

Objective

Approximately 50% of adolescents who have undergone scoliosis surgery still experience severe pain one year postoperatively. We explored the postoperative pain trajectory and the potential value of preoperative Thermal Quantitative Sensory Testing (T-QST) as predictor of chronic postsurgical pain after scoliosis surgery.

Design

Single-center prospective cohort study in adolescents undergoing scoliosis surgery.

Outcomes

Prevalence of chronic postsurgical pain (CPSP) one year after scoliosis surgery and postsurgical pain course during this year. The need for rescue medication and the relationship between pre-operative T-QST, acute pain and CPSP.

Results

Thirty-nine patients (mean age 13.9 years; SD 1.9 years) completed the study. One year postoperatively, ten patients (26%) self-reported pain [numeric rating scale (NRS) score ≥ 4]) when moving and two (5%) when in rest. Four of these patients (10.3%) experienced neuropathic pain. The pre-operative cold pain threshold was lower (p = 0.002) in patients with CPSP at 12 months. Preoperative cold and heat pain thresholds were correlated with the number of moderate or severe pain reports (NRS ≥ 4) in the first week postoperatively (r -.426; p = 0.009 and r.392; p = 0.016, respectively).

Conclusions

One year after scoliosis surgery, a significant part of patients (26%) still reported pain, some with neuropathic characteristics. Better diagnosis and treatment is needed; our study suggests that T-QST could be further explored to better understand and treat children with this negative outcome.

Cosmetic surgery and associated chronic postsurgical pain: A cross-sectional study from Norway

OBJECTIVES

Chronic postsurgical pain (CPSP) is a common postoperative sequela. Despite the increasing popularity of cosmetic surgeries, there is a notable lack of research on CPSP in this context, with existing studies focusing on breast surgeries only. To address existing gaps in knowledge, the objective of the present study was to investigate the self-reported prevalence of cosmetic surgery and associated CPSP among Norwegian adults.

METHODS

An online questionnaire consisting of three questions inquiring prior cosmetic surgeries, associated CPSP, and whether participants had sought for pain management was constructed and distributed among adults residing in Norway.

RESULTS

Between November 30, 2022 and December 16, 2022, 1,746 participants were recruited. 10% of respondents, 73.3% of which were female, affirmed to have undergone cosmetic surgery. About 1 in 4 of these was aged 18-29 years. The prevalence of CPSP was 12.6%. CPSP was five times more common among male, compared to female respondents. While about two thirds of participants indicating to have experienced CPSP were aged 18-29 years, CPSP was much less common among individuals of other ages.

CONCLUSION

Consistent with international trends, there appears to be a young and growing population of cosmetic surgery consumers in Norway. According to our results, about 1 in 8 of these might be affected by CPSP, a condition that is notoriously hard to treat and weighting heavily on public healthcare and social welfare systems. Large-scale longitudinal studies further investigating the topic are thus urgently needed.

Microglial voltage-dependent anion channel 1 signaling modulates sleep deprivation-induced transition to chronic postsurgical pain

STUDY OBJECTIVES

This study verified that sleep deprivation before and after skin/muscle incision and retraction (SMIR) surgery increased the risk of chronic pain and investigated the underlying roles of microglial voltage-dependent anion channel 1 (VDAC1) signaling.

METHODS

Adult mice received 6 hours of total sleep deprivation from 1 day prior to SMIR until the third day after surgery. Mechanical and heat-evoked pain was assessed before and within 21 days after surgery. Microglial activation and changes in VDAC1 expression and oligomerization were measured. Minocycline was injected to observe the effects of inhibiting microglial activation on pain maintenance. The VDAC1 inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) and oligomerization inhibitor VBIT-4 were used to determine the roles of VDAC1 signaling on microglial adenosine 5' triphosphate (ATP) release, inflammation (IL-1β and CCL2), and chronicity of pain.

RESULTS

Sleep deprivation significantly increased the pain duration after SMIR surgery, activated microglia, and enhanced VDAC1 signaling in the spinal cord. Minocycline inhibited microglial activation and alleviated sleep deprivation-induced pain maintenance. Lipopolysaccharide (LPS)-induced microglial activation was accompanied by increased VDAC1 expression and oligomerization, and more VDAC1 was observed on the cell membrane surface compared with control. DIDS and VBIT-4 rescued LPS-induced microglial ATP release and IL-1β and CCL2 expression. DIDS and VBIT-4 reversed sleep loss-induced microglial activation and pain chronicity in mice, similar to the effects of minocycline. No synergistic effects were found for minocycline plus VBIT-4 or DIDS.

CONCLUSIONS

Perioperative sleep deprivation activated spinal microglia and increases the risk of chronic postsurgical pain in mice. VDAC1 signaling regulates microglial activation-related ATP release, inflammation, and chronicity of pain.

Development and expansion of a pediatric transitional pain service to prevent complex chronic pain

The prevention of chronic pain is a key priority in North America and around the world. A novel pediatric Transitional Pain Service (pTPS) at the Hospital for Sick Children was established to address four main areas of need, which the authors will describe in more detail: (1) provide comprehensive multi-modal pain management and prevention techniques to children at-risk for the development of chronic pain, (2) provide opioid stewardship for children at-risk for chronic pain and their families at home after discharge, (3) facilitate continuity of pain care for children across transitions between inpatient and outpatient care settings, and (4) support caregivers to manage their child's pain at home. The pTPS works with healthcare providers, patients, and their families to address these areas of need and improve quality of life. Furthermore the service fills the gap between inpatient acute pain services and outpatient chronic pain services (accessible only once pain has persisted for >3 months). In pediatric patients who experience pain in hospital and who have been prescribed opioids, discharge to home or rehabilitation may represent a vulnerable time in which pain may persist and during which analgesic requirements may change. This offers an important opportunity to address and prevent the development of chronic pain, and to monitor opioids while ensuring alternative pain therapy is available. The authors will outline risk factors for persistent postsurgical pain, the development and implementation of a pTPS, present initial clinical outcomes andsuggest areas for future research in this evolving area of care.

Evidence-based guideline on chronic postsurgical pain management in adult patients in resource-restricted setting, 2023: systematic review and guideline

Background

Chronic postsurgical pain (CPSP) after tissue trauma is frequent and may have a long-lasting impact on the functioning and quality of life. The development of CPSP increases the burden on both the patient and the community. This review aims to systematically review articles and, lastly, pull an evidence-based guideline for CPSP management in adult patients in resource-limited areas.

Methodology

The review was reported based on preferred reporting items for the systemic review and meta-analysis (PRISMA) protocol. A literature search was conducted from the Cochrane, PubMed/Medline, and Google Scholar databases, and other gray literature from 2010 to 2022. The conclusion was made based on the level of evidence.

Results

A total of 3521 articles were identified through the database by searching strategies. Finally, by filtering duplicates unrelated to the topics, 22 articles (9 meta-analyses and systematic reviews, 12 systematic reviews, and one cohort study) were selected on the management of CPSP in adult patients. Filtering was made based on the intervention, outcome data of the population, and methodological quality.

Conclusion

Given the complexity and multidimensional nature of chronic postsurgical pain, effective assessment, and management require a comprehensive, multiaxial approach. Adequate preoperative preparation and counseling, potential risk identification and optimization, and use of a multimodal approach, and noninvasive surgical techniques are crucial in reducing the development of chronic postsurgical pain.

Levels of preoperative cerebrospinal fluid pro-inflammatory mediators and chronic pain after total knee arthroplasty surgery

BACKGROUND

Patients undergoing total knee arthroplasty (TKA) surgery are at high risk of chronic postsurgical pain (CPSP). Accumulating evidence suggests an active role of neuroinflammation in chronic pain. However, its role in the progression to CPSP following TKA surgery remains unanswered. Here, we examined the associations between preoperative neuroinflammatory states and pre- and postsurgical chronic pain in TKA surgery.

METHODS

The data of 42 patients undergoing elective TKA surgery for chronic knee arthralgia at our hospital were analyzed in this prospective study. Patients completed the following questionnaires: brief pain inventory (BPI), hospital anxiety and depression scale, painDETECT, and pain catastrophizing scale (PCS). Cerebrospinal fluid (CSF) samples were collected preoperatively and concentrations of IL-6, IL-8, TNF, fractalkine, and CSF-1 were measured by electrochemiluminescence multiplex immunoassay. CPSP severity was ascertained, using the BPI, 6 months postsurgery.

RESULTS

While no significant correlation was observed between the preoperative CSF mediator levels and preoperative pain profiles, the preoperative fractalkine level in the CSF showed a significant correlation with CPSP severity (Spearman's rho = -0.525; p = .002). Furthermore, multivariate linear regression analysis revealed that the preoperative PCS score (standardized β coefficient [β]: .11; 95% confidence interval [CI]: 0.06-0.16; p < .001) and CSF fractalkine level (β: -.62; 95% CI: -1.10 to -0.15; p = .012) were independent predictors of CPSP severity 6 months after TKA surgery.

CONCLUSIONS

We identified the CSF fractalkine level as a potential predictor for CPSP severity following TKA surgery. In addition, our study provided novel insights into the potential role of neuroinflammatory mediators in the pathogenesis of CPSP.

Predictors of Chronic Pain in Elderly Patients Undergoing Total Knee and Hip Arthroplasty: A Prospective Observational Study

BACKGROUND

Chronic postsurgical pain (CPSP) after total knee arthroplasty and total hip arthroplasty (TKA and THA) is an important clinical problem in which many factors play a role. The risk factors for CPSP in elderly individuals are currently unknown. Therefore, our aim was to predict the risk factors for CPSP after TKA and THA and to provide help regarding early screening and interventions for elderly individuals at risk.

METHODS

In this prospective observational study, we collected and analyzed 177 TKA patients and 80 THA patients. Based on pain results at the 3-month follow-up, they were divided into the no chronic postsurgical pain and CPSP groups, respectively. The preoperative baseline conditions, including pain intensity (Numerical Rating Scale) and sleep quality (Pittsburgh Sleep Quality Index), as well as intraoperative and postoperative factors, were compared. Factors with P < .05 were included in binary regression analyses to establish prediction models for CPSP after TKA and THA.

RESULTS

The prevalence of CPSP was 20.9% after TKA and 7.5% after THA. The preoperative sleep disorders were an independent risk factor of CPSP after TKA, but no risk factors of CPSP after THA were identified.

CONCLUSION

This study indicated that the prevalence of CPSP after TKA was significantly higher than after THA, and that preoperative sleep disorders were an independent risk factor for CPSP after TKA, which may aid clinicians in screening people at risk for CPSP for primary prevention.

Current Approaches to Four Challenging Pain Syndromes

During a conference of pain specialists, some of the experts addressed the potential management of four prevalent but difficult painful conditions, namely, chronic postsurgical pain (CPSP), knee osteoarthritis, chest trauma, and facet joint arthropathy. In all cases, the conditions posed challenges in accurate diagnoses as well as safe, effective treatments, especially using locoregional blocks. It is not clear why some surgical patients develop CPSP and others do not, although some risk factors have been identified. More importantly, the transitional phase of pain from acute to chronic deserves greater scrutiny. It appears as if more aggressive and more effective perioperative and postoperative analgesia could help mitigate or possibly prevent CPSP. Knee osteoarthritis is prevalent but is often managed pharmacologically and then with joint replacement; many patients simply live with the condition which can be viewed as a disease of the entire joint. New approaches with intra-articular injections of hyaluronic acid, platelet-rich plasma, and botulinum toxin may provide safe, effective, and durable pain control. Chest trauma can be extremely painful and a source of morbidity, but its management tends to rely on watchful waiting and drug therapy. New approaches to regional nerve blocks can be beneficial and may reduce troublesome symptoms such as the inability to cough or clear the lungs. Facet joint arthropathy is very prevalent among older people but is not completely clarified. It may be the source of intense pain with limited management strategies. The role of nerve blocks in facet joint arthropathy is an important new addition to the armamentarium of pain management, particularly for geriatric patients.

Association Between Power Doppler Ultrasound Signals and Chronic Pain After Total Knee Arthroplasty: A Cross-Sectional Explorative Study

Purpose

Some patients experience chronic postsurgical pain (CPSP) after total knee arthroplasty (TKA) despite the absence of clinical or radiographic abnormalities. Postoperative synovitis as a cause of CPSP after TKA has received limited research attention. This study aimed to investigate the relationship between synovitis after TKA and CPSP.

Patients and Methods

A total of 111 knees of 85 patients, with at least 1-year post-TKA follow-up, were assessed retrospectively and cross-sectionally. Power Doppler (PD) ultrasonography was used to detect the synovial hypervascularity associated with synovitis. The knee joint was divided into 15 areas, and PD signals were graded semi-quantitatively (0-3) in each area, the sum of which was defined as the total PD score. Clinical information regarding CPSP, including the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscales, was recorded. The relationship between pain and PD ultrasonography findings was accessed. Patients were divided into two groups (CPSP+ and CPSP- groups) based on pain severity. Clinical information, including PD ultrasonography findings and other possible causes, was compared between the groups.

Results

The WOMAC pain subscale was significantly correlated with the total PD score and maximum PD grade (r=0.3977, p<0.0001; r=0.2797, p=0.0029; respectively). The CPSP+ group had a significantly higher maximum PD grade and total PD score than the CPSP- group (median [interquartile range]: 2 [1, 2] vs 1 [1, 2], p=0.0001; 6 [2, 11] vs 2 [1, 4], p=0.0002; respectively). Multiple and logistic regression analyses showed that the total PD score was an independent factor for the WOMAC pain subscale (β=0.3822, 95% confidence interval [CI]=0.1460, 0.6184, p=0.00176) and CPSP (odds ratio=1.19, 95% CI=1.01, 1.41, p=0.0424).

Conclusion

This study indicated a possible association between the total PD score and chronic pain after TKA; however, further studies are needed to corroborate these findings.

Endogenous μ-opioid-Neuropeptide Y Y1 receptor synergy silences chronic postoperative pain in mice

Tissue injury creates a delicate balance between latent pain sensitization (LS) and compensatory endogenous analgesia. Inhibitory G-protein-coupled receptor (GPCR) interactions that oppose LS, including μ-opioid receptor (MOR) or neuropeptide Y Y1 receptor (Y1R) activity, persist in the spinal cord dorsal horn (DH) for months, even after the resolution of normal pain thresholds. Here, we demonstrate that following recovery from surgical incision, a potent endogenous analgesic synergy between MOR and Y1R activity persists within DH interneurons to reduce the intensity and duration of latent postoperative hypersensitivity and ongoing pain. Failure of such endogenous GPCR signaling to maintain LS in remission may underlie the transition from acute to chronic pain states.

Protocol for Development and Validation of Multivariable Prediction Models for Chronic Postsurgical Pain Following Video-Assisted Thoracic Surgery

Purpose

Chronic postsurgical pain (CPSP) is a common complication after thoracic surgery and associated with long-term adverse outcomes. This study aims to develop two prediction models for CPSP after video-assisted thoracic surgery (VATS).

Methods and Analysis

This single-center prospective cohort study will include a total of 500 adult patients undergoing VATS lung resection (n = 350 for development and n = 150 for external validation). Patients will be enrolled continuously at The First Affiliated Hospital of Soochow University in Suzhou, China. The cohort for external validation will be recruited in another time period. The outcome is CPSP, which is defined as pain with the numerical rating scale score of 1 or higher 3 months after VATS. Univariate and multivariable logistic regression analyses will be performed to develop two CPSP prediction models based on patients' data of postoperative day 1 and day 14, respectively. For internal validation, we will use the bootstrapping validation technique. For external validation, the discrimination capability of the models will be assessed using the area under the receiver operating characteristic curve, and the calibration will be evaluated using the calibration curve and Hosmer-Lemeshow goodness-of-fit statistic. The results will be presented in model formulas and nomograms.

Conclusion

Based on the development and validation of the prediction models, our results contribute to early prediction and treatment of CPSP after VATS.

Trial Registration

Chinese Clinical Trial Register (ChiCTR2200066122).

Dexamethasone and persistent wound pain: a prespecified analysis of the randomised Perioperative Administration of Dexamethasone and Infection (PADDI) trial

BACKGROUND

Dexamethasone is commonly administered intraoperatively to prevent postoperative nausea and vomiting and is believed to have analgesic properties. It is unknown whether it has an impact on chronic wound pain.

METHODS

In this prespecified embedded superiority substudy of the randomised PADDI trial, patients undergoing non-urgent noncardiac surgery received dexamethasone 8 mg or placebo intravenously after induction of anaesthesia, and were followed up for 6 months postoperatively. The primary outcome was the incidence of pain in the surgical wound at 6 months. Secondary outcomes included acute postoperative pain and correlates of chronic postsurgical pain.

RESULTS

We included 8478 participants in the modified intention-to-treat population (4258 in the dexamethasone group and 4220 in the matched placebo group). The primary outcome occurred in 491 subjects (11.5%) in the dexamethasone arm and 404 (9.6%) subjects in the placebo arm (relative risk 1.2, 95% confidence interval 1.06-1.41, P=0.003). Maximum pain scores at rest and on movement in the first 3 postoperative days were lower in the dexamethasone group compared with the control group {median 5 (inter-quartile range [IQR] 3.0-8.0) vs 6 (IQR 3.0-8.0) and median 7 (IQR 5.0-9.0) vs 8 (IQR 6.0-9.0), P<0.001 for both}. Severity of postoperative pain was not predictive of chronic postsurgical pain. The severity of chronic postsurgical pain and the frequency of neuropathic features did not differ between treatment groups.

CONCLUSION

Administration of dexamethasone 8 mg i.v. was associated with an increase in the risk of pain in the surgical wound 6 months after surgery.

CLINICAL TRIAL REGISTRATION

ACTRN12614001226695.

Non-opioid analgesics for the prevention of chronic postsurgical pain: a systematic review and network meta-analysis

BACKGROUND

Chronic postsurgical pain is common after surgery. Identification of non-opioid analgesics with potential for preventing chronic postsurgical pain is important, although trials are often underpowered. Network meta-analysis offers an opportunity to improve power and to identify the most promising therapy for clinical use and future studies.

METHODS

We conducted a PRISMA-NMA-compliant systematic review and network meta-analysis of randomised controlled trials of non-opioid analgesics for chronic postsurgical pain. Outcomes included incidence and severity of chronic postsurgical pain, serious adverse events, and chronic opioid use.

RESULTS

We included 132 randomised controlled trials with 23 902 participants. In order of efficacy, i.v. lidocaine (odds ratio [OR] 0.32; 95% credible interval [CrI] 0.17-0.58), ketamine (OR 0.64; 95% CrI 0.44-0.92), gabapentinoids (OR 0.67; 95% CrI 0.47-0.92), and possibly dexmedetomidine (OR 0.36; 95% CrI 0.12-1.00) reduced the incidence of chronic postsurgical pain at ≤6 months. There was little available evidence for chronic postsurgical pain at >6 months, combinations agents, chronic opioid use, and serious adverse events. Variable baseline risk was identified as a potential violation to the network meta-analysis transitivity assumption, so results are reported from a fixed value of this, with analgesics more effective at higher baseline risk. The confidence in these findings was low because of problems with risk of bias and imprecision.

CONCLUSIONS

Lidocaine (most effective), ketamine, and gabapentinoids could be effective in reducing chronic postsurgical pain ≤6 months although confidence is low. Moreover, variable baseline risk might violate transitivity in network meta-analysis of analgesics; this recommends use of our methods in future network meta-analyses.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO CRD42021269642.

Pilot Investigation of Somatosensory Functioning and Pain Catastrophizing in Pediatric Spinal Fusion Surgery

PURPOSE

Chronic post-surgical pain (CPSP) is a significant concern and contributes to the opioid epidemic; however, little is known about CPSP in young people.

DESIGN

This prospective study aimed to identify sensory, psychological, and demographic factors that may increase the risk of CPSP after spinal fusion surgery for children and adolescents with idiopathic scoliosis.

METHODS

32 children and adolescents from two children's hospitals completed quantitative sensory testing (QST) and the Pain Catastrophizing Scale Child (PCS-C) pre-and 4-6 months post spinal fusion surgery. Between-group differences were assessed using an independent samples t-test. Pearson's correlations and stepwise linear regression were used to assess the relationship between variables at both time points.

RESULTS

56% of patients endorsed pain post-surgery. They were more sensitive tomechanical detection on both a control non-pain site (r = -2.87, p = .004) and the back (r = -1.83, p = .04), as well as pressure pain (r=-2.37, p = .01) on the back. This group also reported worse pain scores pre-surgery. Pre-surgery helplessness positively correlated with preoperative pain (r = .67 p < .001), and age was negatively correlated with the post-surgical catastrophizing total score (r =-.39, p = .05), suggesting that younger patients endorsed more pain-related worry after surgery.

CONCLUSIONS

Patients who present with pain during their preoperative appointment may need to be monitored with increased vigilance throughout the perioperative period, possibly with bedside QST and psychological questionnaires, which nurses could administer. Biobehavioral interventions targeting pain intensity and feelings of helplessness and anxiety during the preoperative period may alleviate the transition to CPSP.

Association of Common Pediatric Surgeries With New Onset Chronic Pain in Patients 0-21 Years of Age in the United States

Chronic pain (CP) is a major public health issue. While new onset CP is known to occur frequently after some pediatric surgeries, its incidence after the most common pediatric surgeries is unknown. This retrospective cohort study used insurance claims data from 2002 to 2017 for patients 0 to 21 years of age. The primary outcome was CP 90 to 365 days after each of the 20 most frequent surgeries in 5 age categories (identified using CP ICD codes). Multivariable logistic regression identified surgeries and risk factors associated with CP after surgery. A total of 424,590 surgical patients aged 0 to 21 were included, 22,361 of whom developed CP in the 90 to 365 days after surgery. The incidences of CP after surgery were: 1.1% in age group 0 to 1 years; 3.0% in 2 to 5 years; 5.6% in 6 to 11 years; 10.1% in 12 to 18 years; 9.9% in 19 to 21 years. Some surgeries and patient variables were associated with CP. Approximately 1 in 10 adolescents who underwent the most common surgeries developed CP, as did a striking percentage of children in other age groups. Given the long-term consequences of CP, resources should be allocated toward identification of high-risk pediatric patients and strategies to prevent CP after surgery. PERSPECTIVE: This study identifies the incidences of and risk factors for chronic pain after common surgeries in patients 0 to 21 years of age. Our findings suggest that resources should be allocated toward the identification of high-risk pediatric patients and strategies to prevent CP after surgery.

Effect of the Paravertebral Block on Chronic Postsurgical Pain After Thoracic Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

This study aimed to identify the benefits of thoracic paravertebral block (PVB) by focusing on its role in reducing chronic postsurgical pain (CPSP) after thoracic surgery.

DESIGN

A systematic review and meta-analysis of randomized controlled trials (RCTs).

SETTING

Electronic databases, including PubMed, EMBASE, CENTRAL, Scopus, and Web of Science, were searched to identify studies.

PARTICIPANTS

Patients undergoing thoracic surgeries.

INTERVENTION

Paravertebral block for postoperative analgesia.

MEASUREMENT AND MAIN RESULTS

A total of 1,028 adult patients from 10 RCTs were included in the final analysis. The incidence of CPSP at 3 months after surgery was not reduced in the PVB group compared with the no-block (odds ratio [OR] 0.59, 95% CI 0.34-1.04; p = 0.07; I² = 6.96%) and other-block (OR 1.39, 95% CI 0.30-6.42; p = 0.67; I² = 77.75%) groups. The PVB did not significantly reduce the incidence of CPSP after 6 months from surgery when compared with no block (OR 0.44, 95% CI 0.08-2.53; p = 0.36; I² = 87.53%) and other blocks (OR 1.17, 95% CI 0.71-1.95; p = 0.93; I² = 45.75%). The PVB significantly decreased postoperative pain at 24 and 48 hours at rest compared with the no- block group. The pain score was higher in the PVB group than in the other block groups 48 hours after surgery at rest.

CONCLUSIONS

Thoracic PVB does not prevent CPSP after thoracic surgery. Further large RCTs are required to confirm and validate the authors' results.

Does Preoperative Hookwire Localization Influence Postoperative Acute and Chronic Pain After Video-Assisted Thoracoscopic Surgery: A Prospective Cohort Study

Purpose

This study aimed to investigate whether preoperative computerized tomography-guided hookwire localization-associated pain could affect acute and chronic postsurgical pain (CPSP) in patients undergoing video-assisted thoracoscopic surgery (VATS).

Methods

We enrolled 161 adult patients who underwent elective VATS; sixty-nine patients experienced hookwire localization (Group A) and 69 did not (Group B). Group A was further subdivided into the multiple localization group (n=35, Group A_multiple) and the single localization group (n=34, Group A_single) according to the number of hookwires. The numerical rating scale (NRS) was used preoperatively, during recovery at the post-anesthesia care unit (PACU), and the first two days, 3 and 6 months postoperatively. Furthermore, multivariate regression analysis was used to identify the risk factors associated with CPSP. The postoperative adverse events, length of hospital stay, and satisfaction in pain management were also recorded.

Results

The incidence and severity of acute postoperative pain were similar between Group A and Group B (p > 0.05). The incidence (56.5% vs 30.4%, p = 0.002) and the NRS scores (2.0 [2.0-3.0] vs 1.0 [1.0-2.0], p = 0.011) for CPSP were significantly higher in Group A than in Group B at 3 months postoperatively. On subgroup analysis, compared with Group A_single, the intensity of CPSP (2.0 [2.0-3.0] vs 2.0 [1.0-2.0], p = 0.005) in Group A_multiple was slightly higher at 3 months postoperatively. Conversely, the CPSP incidence (60.0% vs 29.4%, p = 0.011) was significantly higher at 6 months postoperatively in Group A_multiple. The multivariate regression analysis further validated hookwire localization as a risk factor for CPSP (odds ratio: 6.199, 95% confidence interval 2.049-18.749, p = 0.001). Patient satisfaction relating to pain management at 3 months postoperatively was lower in Group A (p = 0.034).

Conclusion

The preoperative pain stress of hookwire localization increased the incidence and intensity of CPSP rather than acute pain at 3 months postoperatively, especially in patients with multiple hookwires.

Change in perioperative neutrophil-lymphocyte ratio as a potential predictive biomarker for chronic postsurgical pain and quality of life: an ambispective observational cohort study

Introduction

Accurate and accessible predictors of chronic postsurgical pain (CPSP) to identify high-risk postsurgical patients are prerequisite for preventive and interventional strategies. We investigated the incidence and risk factors of CPSP after abdominal surgery, with a focus on plasma immunological markers.

Materials and methods

This was a retrospective analysis of patients who underwent abdominal surgery under general anesthesia at a tertiary center between January 2021 and January 2022. The preoperative demographics, laboratory test data, and surgical factors of the participants were collected from the electronic medical record system. Postoperative pain intensity and living conditions at 1 year after discharge from the hospital were assessed via a phone survey. Univariate and multivariate analyses were used to explore independent risk factors associated with CPSP.

Results

A total of 968 patients were included, and 13.53% (n = 131 of 968) of patients reported CPSP 1 year after surgery. Patients with older age, open surgery, higher American Association of Anesthesiologists classification, patient-controlled intravenous analgesia application, longer surgery duration, higher postoperative absolute neutrophil count, and neutrophil-lymphocyte ratio (NLR), lower postoperative absolute lymphocyte count, and higher white blood cell count, were more likely to suffer from CPSP. A changed ratio of NLR (postoperative to preoperative) ≥ 5 significantly correlated with CPSP, moderate to severe pain, maximum numeric rating score since discharge from the hospital, and affected quality of life.

Discussion

The changed ratio of NLR could be used for the early identification of patients at risk for CPSP and affect the quality of life to alert the clinician to undertake further assessment.

Postoperative recovery with continuous erector spinae plane block or video-assisted paravertebral block after minimally invasive thoracic surgery: a prospective, randomised controlled trial

BACKGROUND

PROcedure SPECific Postoperative Pain ManagemenT (PROSPECT) guidelines recommend erector spinae plane (ESP) block or paravertebral block (PVB) for postoperative analgesia after video-assisted thoracoscopic surgery (VATS). However, there are few trials comparing the effectiveness of these techniques on patient-centric outcomes, and none evaluating chronic postsurgical pain (CPSP). Furthermore, there are no available trials comparing ultrasound-guided ESP with surgically placed PVB in this patient cohort.

METHODS

We conducted a two-centre, prospective, randomised, double-blind, controlled trial, comparing anaesthesiologist-administered, ultrasound-guided ESP catheter with surgeon-administered, video-assisted PVB catheter analgesia among 80 adult patients undergoing VATS. Participants received a 20 ml bolus of levobupivacaine 0.375% followed by infusion of levobupivacaine 0.15% (10-15 ml h^-1) for 48 h. Primary outcome was Quality of Recovery-15 score (QoR-15) at 24 h. Secondary outcomes included QoR-15 at 48 h, peak inspiratory flow (ml s^-1) at 24 h and 48 h, area under the pain verbal response score vs time curve (AUC), opioid consumption, Comprehensive Complication Index, length of stay, and CPSP at 3 months after surgery.

RESULTS

Median (25-75%) QoR-15 at 24 h was higher in ESP (n=37) compared with PVB (n=37): 118 (106-134) vs 110 (89-121) (P=0.03) and at 48 h: 131 (121-139) vs 120 (111-133) (P=0.03). There were no differences in peak inspiratory flow, AUC, Comprehensive Complication Index, length of hospital stay, and opioid consumption. Incidence of CPSP at 3 months was 12 (34%) for ESP and 11 (31%) for PVB (P=0.7).

CONCLUSIONS

Compared with video-assisted, surgeon-placed paravertebral catheter, erector spinae catheter improved overall QoR-15 scores at 24 h and 48 h but without differences in pain or opioid consumption after minimally invasive thoracic surgery.

CLINICAL TRIAL REGISTRATION

NCT04729712.

Autobiographical memory predicts postsurgical pain up to 12 months after major surgery

ABSTRACT

Recent cross-sectional studies have identified differences in autobiographical memory (AM) among individuals with chronic pain, but the temporal relationship between the 2 is unknown. Moreover, AM has yet to be studied in patients undergoing major surgery. This study addressed these gaps by conducting a prospective, longitudinal study of memory performance, postsurgical pain, and psychosocial factors in 97 adult participants scheduled for major surgery. Memories were evaluated using the Autobiographical Memory Test before and one month after surgery when participants were asked to recall personal events related to positive and pain-related word cues. Responses were coded for level of specificity, emotional valence, and surgery-related content. Questionnaires assessing presence/absence of pain and psychological functioning were administered before and at 1-, 3-, 6-, and 12-month follow-ups. Generalized estimating equations modelled pain at each postsurgical time point with memory variables as predictors. As hypothesized, higher numbers of specific pain memories recalled before surgery predicted lower odds of pain across all time points (OR = 0.58, 95% CI [0.37-0.91]). Participants who took longer to recall pain memories before surgery (OR = 2.65, 95% CI [1.31-5.37]) and those who produced more surgery-related content at the one-month assessment (OR = 1.31, 95% CI [1.02-1.68]) had greater odds of reporting postsurgical pain up to 12 months later. These findings indicate that presurgical AM biases are risk factors for development and maintenance of postsurgical pain. To the extent that these biases are causal, presurgical interventions that modify the quality and content of patients' memories may prove to be promising strategies in the prevention of chronic postsurgical pain.

The Association Between Long-Term Spicy-Food Consumption and the Incidence of Chronic Postsurgical Pain After Cesarean Delivery: An Observational Study

Background

Our previous study found that a long-term diet incorporating spicy foods can reduce the human basal pain threshold. Capsaicin is the pungent ingredient in chili peppers. Transient receptor potential vanilloid type1 is the capsaicin receptor expressed in the oral cavity and is the primary sensory neuron of the “pain” pathway. Few studies have examined the association between long-term spicy diet and chronic postsurgical pain (CPSP). Women who underwent elective cesarean section (eCS) have consistent characteristics of CPSP. This study aimed to investigate the relationship between a long-term spicy diet and the incidence of CPSP after eCS.

Methods

Participants were divided into a low frequency group (LF, numerical rating scale (NRS)<5) for spicy food consumption and a high frequency group (HF, NRS≥5) by receiver operator characteristic analysis. The primary outcome was the incidence of CPSP three months after eCS. Propensity score matching (PSM) analysis was performed between the two frequency groups. Stepwise logistic regression analysis was then performed.

Results

Of the 1029 enrolled patients, data from 982 were analyzed 3 months after eCS. After PSM, the incidence of CPSP in the HF group (30.1% [108/359]) was higher than that in the LF group (19.8% [71/359]; P = 0.001). Compared with the LF group, the risk of CPSP in the HF group increased 1.61 times by 3 months (95% CI 1.18–2.20, P = 0.003). PSM results found that 1 year, the incidence of CPSP in the HF group (15.2% [56/369]) was higher than that in the LF group (8.1% [30/369], P = 0.003).

Conclusion

With an NRS≥5 as a boundary, women who consumed spicy food ≥ 2 days/week were more likely to have CPSP than those who consumed spicy food < 2 days/week.

Genetic and epigenetic mechanisms influencing acute to chronic postsurgical pain transitions in pediatrics: Preclinical to clinical evidence

Background

Chronic postsurgical pain (CPSP) in children remains an important problem with no effective preventive or therapeutic strategies. Recently, genomic underpinnings explaining additional interindividual risk beyond psychological factors have been proposed.

Aims

We present a comprehensive review of current preclinical and clinical evidence for genetic and epigenetic mechanisms relevant to pediatric CPSP.

Methods

Narrative review.

Results

Animal models are relevant to translational research for unraveling genomic mechanisms. For example, Cacng2, p2rx7, and bdnf mutant mice show altered mechanical hypersensitivity to injury, and variants of the same genes have been associated with CPSP susceptibility in humans; similarly, differential DNA methylation (H1SP) and miRNAs (miR-96/7a) have shown translational implications. Animal studies also suggest that crosstalk between neurons and immune cells may be involved in nociceptive priming observed in neonates. In children, differential DNA methylation in regulatory genomic regions enriching GABAergic, dopaminergic, and immune pathways, as well as polygenic risk scores for enhanced prediction of CPSP, have been described. Genome-wide studies in pediatric CPSP are scarce, but pathways identified by adult gene association studies point to potential common mechanisms.

Conclusions

Bench-to-bedside genomics research in pediatric CPSP is currently limited. Reverse translational approaches, use of other -omics, and inclusion of pediatric/CPSP endophenotypes in large-scale biobanks may be potential solutions. Time of developmental vulnerability and longitudinal genomic changes after surgery warrant further investigation. Emergence of promising precision pain management strategies based on gene editing and epigenetic programing emphasize need for further research in pediatric CPSP-related genomics.

Abstract No. : ABS2524 : Preventive strategies in chronic persistent postsurgical pain following breast cancer Surgery- A systematic review and meta-analysis,

Background and Aims:

Chronic persistent postsurgical pain(CPCP) following breast cancer surgery is associated with decreased health-related quality of life and additional psychological distress.This meta-analysis aimed to evaluate the effect of various preventive strategies used for reducing the chronic persistent post-surgical pain following breast cancer surgery.

Methods:

An extensive search was conducted on online databases like PubMed, Google Scholar, Science Direct, and Embase. All the relevant randomised controlled trials(RCT) that are published up to June 2021 were included in this review. Patients with breast cancer who have undergone lumpectomy with or without axillary lymph node dissection and modified radical mastectomy were included in the study. The primary outcome measure was pain intensity. Incidence of chronic pain at 3 months using a verbal rating scale (VRS), visual analog scale (VAS), and numerical rating scales (NRS) were compared with control groups. The association between the primary outcome and preventive strategies was assessed using relative risk.

Results:

Incidence of CPSP at 3-month was assessed by 21 RCTs. This meta-analysis included 1610 patients (804 in intervention groups and 806 controls). Intervention reduced the incidence of CPSP at 3-month by 37% as compared to the control group and this reduction was statistically significant [Relative risk: 0.64: 0.54-0.75; p<0.001; I²=24.2%]. There was no publication bias and low heterogeneity among the studies (figure 1).

Conclusion:

In patients undergoing breast cancer surgery, intervention in the form of block or drug reduces the incidences of CPSP at three months post-surgery

Abstract No. : ABS2276: Modulation of mRNA expression of mTORC1 and IL-6 and comparison of the efficacy and safety of transdermal fentanyl versus transdermal buprenorphine for prevention of chronic persistent post surgical pain in head and neck cancer patients: A randomised, pilot study

Background and Aims:

This study compared the efficacy and safety of transdermal buprenorphine (TDB) and transdermal fentanyl (TDF) in prevention of chronic persistent post-surgical pain (CPPP) and modulation of mRNA expression of interlukin (IL-6) and mTORC1 genes in patients of head and neck carcinoma (HNC).

Methods:

Patients aged >18 years who were operated for HNC with numerical rating scale(NRS)pain scores≥4/10 on post-operative day-6 were enroled. A baseline assessment was done and written informed consent was obtained. The pain intensity and severity were evaluated byNRS-pain, PDQ scores (pain detect questionnaire), and neuropathic pain symptom inventory (NPSI) scores and quality of life was evaluated by utilizing Short Form-12 (SF-12). Gene expression analysis was carried out at baseline and after treatment completion. On post-operative day 6, patients of group F (n=20) received TDF (50 µg/hour) and group B (n=20) received TDB (10 µg/hour).

Results:

the A total of 40 patients with 20 in each group were included in this study. Following 12 weeks of treatment, gene studiesdemonstrated downregulation of the mRNA expression of IL-6 and mTORC1, which was statistically significant in both groups. A statistically significant decline in NRS-Pain, PDQ scores and NPSI scores and a statistically significant improvement in the physical and mental component scores of SF-12 was also observed in both groups (table 1).

Conclusion:

Significant downregulation in mRNA expression of IL-6 and mTORC1 was observed after both transdermal fentanyl and transdermal buprenorphine and both were equally efficacious for prevention of CPPP and improving quality of life following HNC surgery.

The Impact of Optimism on Cancer-Related and Postsurgical Cancer Pain: A Systematic Review

BACKGROUND

The impact of psychological factors on pain levels continues to be of interest throughout a cancer patient's journey. The relationship between pain and optimism has been described previously in patients with various diseases.

OBJECTIVES

We further investigated the effect of optimism on pain levels felt by patients diagnosed and living with cancer before and after surgery.

MATERIALS AND METHODS

The search strategy for relevant articles from inception through June 2020 included five databases. The main outcome of interest was the effect of optimism on cancer-related pain.

RESULTS

We identified 482 studies. After the full-text screening, seven articles meeting the inclusion criteria were included. Seven studies were analyzed and are included in the data table. Of the seven included articles, four articles described the association of optimism with cancer pain; four articles studied the relationship between optimism and chronic postsurgical pain (CPSP), and one article investigated optimism's relationship with acute postsurgical pain (APSP). All articles observed a negative correlation between optimism and pain levels.

CONCLUSION

Despite the differences in the pathophysiology of pain types investigated, and which stage of the patient's journey pain was experienced, all studies reported a negative association with the level of optimism and pain described by patients. Therefore, promoting and supporting psychological coping techniques, including optimism for cancer patients may decrease patients' suffering, increase their quality of life at different cancer stages, and reduce opioid use.

Predictors of Chronic Postsurgical Pain in Elderly Patients Undergoing Hip Arthroplasty: A Multi-Center Retrospective Cohort Study

Background

Identifying patients at high risk of developing chronic postsurgical pain (CPSP) is of extreme importance in order to help launch appropriate therapeutic strategies and intensive initiation of pain management.

Aim

In this study, we aimed to conduct a multi-center retrospective cohort study to establish a prognostic model and a nomogram to predict the risks of CPSP in elderly patients who underwent hip arthroplasty at 6 months postoperatively.

Methods

We collected data from 736 patients aged >65 years who had undergone hip arthroplasty from October 1, 2016 to September, 30, 2018 at multiple tertiary referral centers in Guangzhou, China. All data were randomly stratified into a training set and a testing set at a ratio of 8:2. Data were analyzed via multiple logistic regression analysis with receiver operating characteristic (ROC) curves and areas under the curve. This model was further validated by estimating calibration and discrimination. A nomogram was ultimately developed.

Results

A total of 736 eligible patients were enrolled, 27.20% of whom developed CPSP within 6 months postoperatively. Preoperative pain in the surgical area (OR=2.456, 95% CI:1.814–3.327, P<0.001), preoperative depression state (OR=1.256, 95% CI:1.146–1.378, P<0.001), surgical type (OR=7.138, 95% CI:3.548–14.364, P<0.001), acute postoperative numerical rating scale score (OR=5.537, 95% CI:3.607–8.499, P<0.001) and analgesic type (patient-controlled epidural analgesia: OR=0.129, 95% CI:0.055–0.299, P<0.001; patient-controlled intravenous analgesia: OR=0.033, 95% CI:0.011–0.097, P<0.001) were identified as independent significant factors associated with CPSP. A prognostic model was established and further validated. An ROC curve confirmed the predictive ability of this model with a high sensitivity value of 92.12% (95% CI:86.90–95.74) and specificity value of 91.72% (95% CI:88.77–94.11). A nomogram was developed to simplify the use of the predictive model in clinical practice.

Conclusion

This prognostic model could be of great value in clinical practice, serving as the basis for early personalized analgesic management of elderly patients undergoing hip arthroplasty.

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Role of caveolin-1 in chronic postsurgical pain in rats

Chronic postsurgical pain (CPSP) has a high incidence, but the underlying mechanisms remain elusive. Previous studies have indicated that caveolin-1 (Cav-1) plays a notable role in pain modulation. To study the role of Cav-1 in CPSP in the present study, a rat model of skin/muscle incision and retraction (SMIR) was established. Under anesthesia, skin and superficial muscle of the medial thigh were incised and a small pair of retractors inserted. It was revealed that SMIR increased the expression of Cav-1 in the dorsal root ganglion (DRG) and the injured tissue around the incision. Furthermore, the infiltration of endothelial cells and macrophages in the injured tissue around the incision increased constantly, and the vascular permeability increased due to the destruction of the vascular endothelial barrier function around the injured tissue. Cav-1 was mainly expressed by CD68-positive macrophages and CD34-positive endothelial cells in the injured tissues around the incision, while it was also primarily localized in the medium and large neurofilament 200-positive neurons and a small number of calcitonin gene-related peptide- and isolectin B4-positive small and medium-sized neurons in the DRG. The results demonstrated that the sustained high expression levels of Cav-1 in the injured tissue around the incision could lead to the dysfunction of the vascular endothelial barrier and, thus, could induce the inflammatory response through the lipoprotein transport of endothelial cells, thereby resulting in peripheral sensitization. In addition, the sustained high expression levels of Cav-1 in the DRG could sensitize large-sized neurons and change the transmission mode of noxious stimuli. The findings of the present study indicated that a Cav-1-mediated process could participate in neuronal transmission pathways associated with pain modulation.

Effect of Bilateral Quadratus Lumborum Block Type I on Patient Satisfaction and Incidence of Chronic Postsurgical Pain Following Cesarean Section-A Randomized Controlled Trial

BACKGROUND

Quadratus lumborum block (QLB) provides a reduction in pain scores and opioid consumption after cesarean section (CS). Intrathecal morphine (ITM) is still considered as the gold standard of acute postoperative pain therapy, but it does have some significant side effects. The aim of this clinical study was to evaluate whether performing the quadratus lumborum block type I in patients undergoing CS would be associated with an increased satisfaction of pain therapy and a decreased incidence of chronic postsurgical pain (CPSP).

METHODS

Sixty patients scheduled for elective CS were enrolled. All patients received spinal anesthesia and were randomly allocated to either the QLB group (received bilateral quadratus lumborum block type I with the use of 24 m mL 0.375% ropivacaine) or the control group (received no block). The level of satisfaction was evaluated using a three-step scale and the answers provided in a questionnaire regarding the patients' satisfaction with the method of postoperative pain treatment in the first 48 h. After a 6-month period, all patients were interviewed to evaluate the incidence and possible severity of CPSP.

RESULTS

Satisfaction scores were significantly lower in the QLB group than in the control group (p = 0.0000). There were no significant differences between the QLB and control groups regarding the occurrence of chronic postsurgical pain after 6 months following CS (p = 0.102). No statistical differences between the groups were recorded when we compared the results of the questionnaire after a period of 48 h from CS (the number of participants were limited in number).

CONCLUSIONS

QLB type I is an analgetic option that increased the satisfaction of parturients with pain therapy after CS compared to patients who did not receive the block, and there is a tendency for a lower incidence of CPSP.

Publication Trends and Hot Spots in Chronic Postsurgical Pain (CPSP) Research: A 10-Year Bibliometric Analysis

Purpose

Aging populations and increasing quality of life requirements have attracted growing efforts to study chronic postsurgical pain (CPSP). However, a diverse range of factors are involved in CPSP development, which complicates efforts to predict and treat this disease. To advance research in this field, our study aimed to use bibliometric analysis to quantitatively and qualitatively evaluate CPSP research and predict research hot spots over the last 10 years.

Methods

Relevant publications between 2011 and 2020 were extracted from the Web of Science Core Collection database. CiteSpace software (v5.7.R2) and the Online Analysis Platform of Literature Metrology were used to analyze research attributes including countries and authors, keywords and co-occurrence, and burst detection to predict trends and hot spots.

Results

A total of 2493 publications were collected with the number of annual publications showing nearly threefold increase over the past decade. Articles were the primary publication type with the United States as the leading country and the center of national collaboration. Johns Hopkins University provided the leading influence within the CPSP field. Postoperative pain, multimodal analgesia, quality of life, opioid, microglia, cesarean delivery, inguinal hernia, chronification, genetic polymorphism, and lidocaine were the top 10 clusters in co-occurrence cluster analysis. Moreover, burst detection was shown that epidural analgesia, nerve injury, total hip arthroplasty were the new hot spots within the CPSP field.

Conclusion

Bibliometric mapping not only defined the overall structure of CPSP-related research but its collective information provides crucial assistance to direct ongoing research efforts. The prominent keywords including "risk factor" and "multimodal analgesia" indicate that CPSP prevention and new treatment methods remain hot spots. Nonetheless, the recognition that CPSP is complex and changeable, proposes comprehensive biopsychosocial approaches are needed, and these will be essential to improve CPSP interventions and outcomes.

Prevalence and predictors of chronic postsurgical pain after colorectal surgery: A prospective study

AIM

The aim was to investigate the incidence, characteristics and the potential predictors of chronic postsurgical pain (CPSP) after colorectal surgery.

METHOD

Patients who underwent colorectal surgery at our institution from July 2014 to December 2016 were prospectively enrolled in this study. Perioperative potential demographic, clinical and psychological predictors for CPSP were collected. The follow-up visits were conducted through telephone interviews at 3 and 6 months postoperatively. The interview questionnaire comprised items regarding pain intensity, frequency, site, analgesic administration and impact on activities of daily living.

RESULTS

A total of 624 patients completed the 6-month follow-up and were included in the analysis. CPSP was reported by 32.1% of these patients at 3 months and 21.8% at 6 months after colorectal surgery. The pain interfered with several activities of daily living in a considerable proportion of CPSP cases. At 3 months, the identified predictors of CPSP were young age, preoperative abdominal pain and pain elsewhere, preoperative anxiety and depression, longer duration of surgery, and high pain intensity on movement within 24 h after surgery. Predictors of CPSP at 6 months were young age, preoperative abdominal pain, preoperative anxiety, longer duration of surgery, and high pain intensity on movement within 24 h after surgery.

CONCLUSION

Chronic pain after colorectal surgery is a common complication associated with young age, preoperative abdominal pain and pain elsewhere, preoperative anxiety and depression, longer duration of surgery, and high pain intensity on movement within 24 h after surgery.

Dorsal Root Ganglion Stimulation for Chronic Groin Pain: A Review

INTRODUCTION

Chronic neuropathic groin pain develops in a significant number of postsurgical patients; however, multiple etiologies have been identified, and this makes it a challenging condition to treat. While treatment often involves a multimodal approach, advancements in neuromodulation technology, particularly dorsal root ganglion (DRG) stimulation, have benefited patients plagued by chronic pain refractory to standard treatment modalities. Our goal was to provide a definitive source of information for interventional pain physicians regarding groin pain and the use of DRG stimulation for its treatment.

MATERIALS AND METHODS

In this narrative review, we provide an overview of groin pain and discuss potential pain generators. We also outline appropriate treatment options with particular interest on DRG stimulation. Lastly, we provide a narrative review of the published literature regarding DRG stimulation for chronic groin pain from a variety of etiologies.

CONCLUSION

DRG stimulation has emerged as an alternative neuromodulatory technique for patients with chronic groin pain. While previous studies suggest substantial sustained pain relief with DRG stimulation in this patient population, prospective randomized controlled studies are necessary before formal recommendations can be made.

Total Knee Arthroplasty Postsurgical Chronic Pain, Neuropathic Pain, and the Prevalence of Neuropathic Symptoms: A Prospective Observational Study in Turkey

Purpose

Chronic post-surgical pain (CPSP) is a detrimental condition that persists at least two months after surgical procedures and seriously affects patients' quality of life. Although its incidence varies according to operation types and definitions, its prevalence is between 3% and 85%. The purpose of this study is to evaluate the prevalence of CPSP and neuropathic pain in patients undergoing TKA for osteoarthritis.

Patients and Methods

In this study, patients who had undergone total knee arthroplasty (TKA) were examined prospectively and observationally. 42 patients were included in the study. Numeric rate scale (NRS) for developing chronic pain, Douleur Neuropathique 4 (DN-4) questionnaire to evaluate neuropathic pain and symptoms, and von Frey filaments to evaluate mechanical hyperesthesia and alladony.

Results

NRS scores were 1 or higher for all patients. Twenty-seven patients constituted the mild pain group (NRS: 1-4), and 15 patients constituted the moderate pain group (NRS: 4-7). The number of patients defined as having "neuropathic pain," according to DN-4 scores, was 17 (40.4%; DN-4 ≥ 4). The moderate pain group reported greater severity of neuropathic symptoms on average than the mild pain group (p = 0.039). When patients knees affected by TKA were divided into suprapatellar, patellar, and infrapatellar regions and evaluated with von Frey filaments, a significant difference was found between the three regions (p < 0.05).

Conclusion

In this study, we showed-unlike other studies-that the rate of neuropathic pain was higher among CPSP patients, and all patients had neuropathic symptoms. In evaluating patients knees with von Frey filaments, we showed that the neuropathic component of patients' pain occurred mostly in the knee's infrapatellar region. Although the incidence of CPSP and neuropathic pain in these patients was higher than expected, we think CPSP, its diagnosis, and its treatment present an important issue that requires further examination.

What Does CATS Have to Do With Cancer? The Cognitive Activation Theory of Stress (CATS) Forms the SURGE Model of Chronic Post-surgical Pain in Women With Breast Cancer

Chronic post-surgical pain (CPSP) represents a highly prevalent and significant clinical problem. Both major and minor surgeries entail risks of developing CPSP, and cancer-related surgery is no exception. As an example, more than 40% of women undergoing breast cancer surgery struggle with CPSP years after surgery. While we do not fully understand the pathophysiology of CPSP, we know it is multifaceted with biological, social, and psychological factors contributing. The aim of this review is to advocate for the role of response outcome expectancies in the development of CPSP following breast cancer surgery. We propose the Cognitive Activation Theory of Stress (CATS) as an applicable theoretical framework detailing the potential role of cortisol regulation, inflammation, and inflammatory-induced sickness behavior in CPSP. Drawing on learning theory and activation theory, CATS offers psychobiological explanations for the relationship between stress and health, where acquired expectancies are crucial in determining the stress response and health outcomes. Based on existing knowledge about risk factors for CPSP, and in line with the CATS position, we propose the SURGEry outcome expectancy (SURGE) model of CPSP. According to SURGE, expectancies impact stress physiology, inflammation, and fear-based learning influencing the development and persistence of CPSP. SURGE further proposes that generalized response outcome expectancies drive adaptive or maladaptive stress responses in the time around surgery, where coping dampens the stress response, while helplessness and hopelessness sustains it. A sustained stress response may contribute to central sensitization, alterations in functional brain networks and excessive fear-based learning. This sets the stage for a prolonged state of inflammatory-induced sickness behavior - potentially driving and maintaining CPSP. Finally, as psychological factors are modifiable, robust and potent predictors of CPSP, we suggest hypnosis as an effective intervention strategy targeting response outcome expectancies. We here argue that presurgical clinical hypnosis has the potential of preventing CPSP in women with breast cancer.

Physical Activity as a Predictor of Chronic Pain Following Pediatric Spinal Surgery

OBJECTIVES

(1) Characterize objective physical activity patterns via actigraphy over 4 months postspinal fusion surgery, and (2) examine associations between activity patterns at 2-week and chronic postsurgical pain (CPSP) status at 4 months.

MATERIALS AND METHODS

Data from 109 youth (10 to 18 y) who underwent spinal fusion surgery at a children's hospital in the Northwestern United States were analyzed. Youth completed questionnaires and actigraphic assessment of physical activity presurgery, and 2 weeks and 4 months postsurgery.

RESULTS

Eighteen percent of youth developed CPSP at 4 months. Presurgery physical activity was similar for youth with and without CPSP. At 2 weeks postsurgery, daily activity levels were lower for youth who developed CPSP as compared with those who did not, including lower mean activity (168 vs. 212 counts/min, P=0.01), fewer activity bouts (n=1.7 vs. 2.6, P=0.02), and shorter bout duration (27 vs. 40 min, P=0.02). Differences in activity were maintained at 4 months such that youth with CPSP had lower mean activity (284 vs. 334 counts/min, P=0.03), as well as greater proportion time spent sedentary and lower proportion time in light activity than youth without CPSP. In adjusted models examining 2-week actigraphy as a predictor of 4-month pain status, mean activity (odds ratio=0.99, P=0.04) and number of activity bouts (odds ratio=0.79, P=0.02) were associated with subsequent CPSP status over and above 2-week pain intensity.

DISCUSSION

Lower activity engagement during the initial weeks following spinal fusion surgery was associated with development of CPSP, suggesting early physical activity limitations as a risk factor for CPSP in youth. Understanding recovery patterns is critical for identifying those at risk for chronic pain and implementing early interventions.

Association Between Sternotomy Versus Thoracotomy and the Prevalence and Severity of Chronic Postsurgical Pain After Mitral Valve Repair: An Observational Cohort Study

OBJECTIVE

Investigate differences in the prevalence and severity of chronic postsurgical pain (CPSP) after cardiac surgery via thoracotomy versus sternotomy are not well-understood.

DESIGN

An observational cohort study.

SETTING

A tertiary care hospital.

PARTICIPANTS

Four hundred twenty-eight patients (sternotomy: 192 patients, thoracotomy: 236 patients) who underwent mitral valve repair.

INTERVENTIONS

A questionnaire about the severity of surgical wound pain evaluated with a numerical rating scale (NRS) was sent. NRS responses for current pain, peak pain in the last four weeks, and average pain in the last four weeks were evaluated.

MEASUREMENTS AND MAIN RESULTS

The main outcomes were the severity of CPSP evaluated using NRS and the prevalence of CPSP. CPSP was defined as pain >0 that developed after a surgical procedure. During the median follow-up of 29 months, 79 patients complained of CPSP. (sternotomy: 15 patients, thoracotomy: 64 patients). Multivariate ordinal logistic regression showed that NRS responses for current pain (adjusted odds ratio [aOR], 3.17; 95% confidence interval [CI] 1.64-6.12; p = 0.001), peak pain in the last four weeks (aOR, 2.00; 95% CI 1.11-3.61; p = 0.021), and average pain in the last four weeks (aOR, 2.21; 95% CI 1.31-3.72; p = 0.003) were significantly higher in patients who underwent thoracotomy. Multivariate logistic regression showed that thoracotomy was an independent predictor of CPSP (aOR, 3.63; 95% CI 1.67-7.88; p = 0.001).

CONCLUSIONS

The prevalence and severity of CPSP were higher among patients who underwent mitral valve repair via thoracotomy than sternotomy.

Chronic postsurgical pain after total knee arthroplasty: A prospective cohort study in Japanese population

OBJECTIVES

To elucidate the prevalence and risk factors of chronic postsurgical pain (CPSP) after primary total knee arthroplasty (TKA) in Japanese population.

METHODS

Consecutive patients undergoing primary TKA in a Japanese tertiary hospital (211 knees) were assessed. CPSP after TKA was defined as moderate to severe pain (VAS >30 mm), either at rest or during walking, one year after surgery. Clinical and radiographic data were compared between CPSP and non-CPSP groups and multivariate logistic regression was used to identify predictors of CPSP.

RESULTS

The prevalence of CPSP was 8.8%. CPSP group showed significantly higher preoperative WOMAC subscales (pain, function and stiffness), higher rate of postoperative coronal malalignment (femorotibial angle >178° or <170°) and larger varus angle of tibial component compared with non-CPSP group. Logistic regression analysis revealed that preoperative higher WOMAC pain and postoperative coronal malalignment were independent risk factors of CPSP. In a subgroup analysis of patients with well-aligned TKA, preoperative pain VAS at rest was the only risk factor of CPSP.

CONCLUSION

Preoperative severe pain and postoperative coronal malalignment were independent risk factors of CPSP after TKA. Preoperative pain management in patients with severe pain and good coronal alignment after TKA possibly minimize the development of CPSP.

Subacute Pain Trajectories following major musculoskeletal surgery in adolescents: A Pilot Study

Background: Adolescents who undergo major surgery experience high rates of disabling acute and chronic postsurgical pain (CPSP). However, little is known about the subacute period when acute to chronic pain transition occurs.

Aims: The aims of this study were to examine feasibility of electronic daily monitoring of pain and opioid use in adolescents during the first 30 days at home following major surgery and identify target features of subacute pain curves associated with CPSP at 4 months.

Methods: Twenty-five youth (10–18 years) undergoing major musculoskeletal surgery reported daily pain severity, interference, and opioid use on the Brief Pain Inventory each evening for 30 days after hospital discharge to form short time series trajectories. At 4 months, youth reported on pain intensity and health-related quality of life. Characteristics of subacute pain severity and interference curves were compared by 4-month CPSP status.

Results: At 4 months, 20.8% of youth met criteria for CPSP. During the 30-day monitoring period, youth who went on to develop CPSP reported high pain severity on 45.9% of days compared to 2.9% of days in youth who recovered (P = 0.005) and high pain interference on 49.4% of days vs. 9.7% in youth who recovered (P = 0.01). Pain variability and rate of change were not significantly associated with CPSP in our pilot sample.

Conclusions: We found it feasible to collect daily pain data in youth recovering at home after major surgery. Pilot findings suggest that daily electronic monitoring may identify early recovery problems at home after surgery. Larger studies are needed to validate subacute pain trajectory features to identify risk for CPSP.

Chronic Pain After Lung Resection: Risk Factors, Neuropathic Pain, and Quality of Life

CONTEXT

Chronic postsurgical pain (CPSP) can occur frequently after thoracic surgery.

OBJECTIVES

This retrospective study aimed to determine CPSP prevalence, risk factors, neuropathic pain (NP) occurrence, and its impact on quality of life.

METHODS

About 200 patients who underwent lung resection via minithoracotomy or thoracoscopy between January 2017 and December 2017 were assessed 4-12 months postoperatively via phone interview for chronic pain by a 0-10 Numeric Rating Scale, for NP using the Douleur Neuropathique 4 test, and for quality of life using a Short Form-36 (SF-36) Health Survey (Italian version).

RESULTS

CPSP incidence was 35% (n = 70 of 200; 95% CI 41-28) of which 31.5% (n = 22 of 70; 95% CI 41-21) was with NP. Only 10% of patients with CPSP reported severe chronic pain. According to univariate analysis, CPSP was associated to moderate and severe acute postoperative pain (P < 0.001), open surgery (P = 0.001), and female gender (P = 0.044). According to multivariable analysis, independent risk factors for CPSP development included moderate-to-severe acute postoperative pain occurrence (odds ratio 32.61; 95% CI 13.37-79.54; P < 0.001) and open surgery (odds ratio 6.78; 95% CI, 2.18-21.03; P = 0.001). NP incidence was higher in female patients (16% in women and 6% in men, respectively; P = 0.040). A significant decrease in all SF-36 Health Survey domain scores was recorded for patients with CPSP and NP (P < 0.001).

CONCLUSION

More than one of three patients who underwent lung resection could develop CPSP, frequently showing neuropathic component. Female gender reported a higher CPSP and NP incidence. Moderate-to-severe acute postoperative pain occurrence and open surgery seem to be independent risk factors for CPSP. Chronic pain and NP have a negative impact on quality of life, decreasing the SF-36 scores of all domains.

10-kHz Spinal Cord Stimulation for Chronic Postsurgical Pain: Results From a 12-Month Prospective, Multicenter Study

Background

Chronic postsurgical pain (CPSP) can be caused by peripheral nerve injury (PNI) resulting from surgical procedures and has a significant neuropathic component. This prospective, single‐arm study was conducted to document the effectiveness of 10‐kHz spinal cord stimulation (10‐kHz SCS) as a treatment for patients with CPSP.

Methods

Subjects with CPSP who were refractory to conventional medical interventions and reported pain scores of ≥5 cm on a 10‐cm VAS underwent trial stimulations lasting up to 14 days. Epidural leads were implanted at locations appropriate for the primary area of pain, and trials resulting in ≥40% pain relief were considered successful. Subjects with successful trials underwent implantation with a permanent 10‐kHz SCS system and were followed for 12 months after implantation.

Results

Of the 34 subjects who underwent trial stimulation, 1 was withdrawn early and 29 (87.9%) had a successful trial and received a permanent implant. After 12 months of treatment, the mean VAS score decreased by 6.5 cm, the response rate was 88.0% (22/25), and 18 subjects (62.1%) were remitters with VAS scores sustained at ≤3.0 cm. Scores for all components of the short‐form McGill Pain Questionnaire 2 were significantly reduced, including affective descriptors of pain. Pain catastrophizing and vigilance, patient function, physical and mental well‐being, and sleep quality all improved over the course of the study. No neurologic deficits reported in the study.

Conclusions

10‐kHz SCS is effective and tolerated in patients with CPSP, and further study of its clinical application in this population is warranted.

Psychosocial Predictors of Acute and Chronic Pain in Adolescents Undergoing Major Musculoskeletal Surgery

Acute and chronic pain delay recovery and impair outcomes after major pediatric surgery. Understanding unique risk factors for acute and chronic pain is critical to developing effective treatments for youth at risk. We aimed to identify adolescent and family psychosocial predictors of acute and chronic postsurgical pain after major surgery in adolescents. Participants included 119 youth age 10 to 18 years (M_age = 14.9; 78.2% white) undergoing major musculoskeletal surgery and their parents. Participants completed presurgery baseline questionnaires, with youth reporting on baseline pain, anxiety, depression, insomnia and sleep quality, and parents reporting on parental catastrophizing and family functioning. At baseline, 2-week, and 4-month postsurgery, youth completed 7 days of daily pain diaries and reported on health-related quality of life. Sequential logistic regression models examined presurgery predictors of acute and chronic postsurgical pain, defined as significant pain with impairment in health-related quality of life. Acute pain was experienced by 27.2% of youth at 2 weeks, while 19.8% of youth met criteria for chronic pain at 4 months. Baseline pain predicted acute pain (odds ratio [OR] = 1.96; 95% confidence interval [CI] = 1.32-2.90), while depressive symptoms (OR = 1.22; 95%CI = 1.01-1.47), and sleep quality (OR = 0.26; 95%CI = 0.08-0.83) predicted chronic pain. Tailored interventions need to be developed and incorporated into perioperative care to address risk factors for acute and chronic pain. PERSPECTIVE: Longitudinal results demonstrate adolescents' presurgery pain severity predicts acute postsurgical pain, while depressive symptoms and poor sleep quality predict chronic postsurgical pain. Tailored interventions should address separate risk factors for acute and chronic pain after adolescent surgery.

Ultrasound-guided erector spinae block for post-thoracotomy pain syndrome in video-assisted thoracic surgery

This article describes our experience with 5 patients with post-thoracotomy pain syndrome after video-assisted thoracoscopic lobectomies, treated with weekly erector spinae plane block. We injected corticosteroid and local anesthetic. At the end of the treatment period, pain scores decreased significantly. Our experience suggests that erector spinae plane block may have a role in the treatment of post-thoracoscopy pain syndrome.

Clinical Analysis of the Effects of Different Anesthesia and Analgesia Methods on Chronic Postsurgical Pain in Patients With Uniportal Video-Assisted Lung Surgery

OBJECTIVES

To understand whether different anesthesia and analgesia methods affected the incidence of chronic postsurgical pain (CPSP) in patients who underwent uniportal video-assisted lung surgery and to explore the influence factors of CPSP.

DESIGN

Retrospective study.

SETTING AND PARTICIPANTS

A total of 120 patients, who underwent selective uniportal video-assisted lung surgery at Zhongshan Hospital from March to June 2018, were enrolled.

INTERVENTIONS

The visual analog scale was used to assess the degree of pain on the first and second postoperative days. At the third and sixth months after surgery, the telephone follow-up was conducted for the survey of the numerical rating scale. The incidence of acute and chronic pain in different anesthesia methods was analyzed, and the relevant factors of CPSP were statistically analyzed.

RESULTS

Among the 111 patients who completed follow-up, no significant difference was noted in the incidences of acute and chronic postsurgical pain between patients who received different anesthesia and analgesia methods (p > 0.05). The incidence of CPSP was 29.7% at 3 months after surgery and 9.0% at 6 months after surgery. The degree of pain within 48 hours after surgery was a risk factor for CPSP (odds ratio [OR] = 2.39, p < 0.05).

CONCLUSION

CPSP accounted for a specific proportion of patients after uniportal video-assisted lung surgery; however, it was significantly lower than that of patients with conventional thoracotomy. The incidence did not differ significantly among anesthesia and analgesia methods. Active and effective control of acute postsurgical pain might reduce the incidence of CPSP.

Chronic postsurgical pain: From risk factor identification to multidisciplinary management at the Toronto General Hospital Transitional Pain Service

Background: Chronic postsurgical pain is a highly prevalent public health problem associated with substantial emotional, social, and economic costs. Aims: (1) To review the major risk factors for chronic postsurgical pain (CPSP); (2) to describe the implementation of the Transitional Pain Service (TPS) at the Toronto General Hospital, a multiprofessional, multimodal preventive approach to CPSP involving intensive, perioperative psychological, physical, and pharmacological management aimed at preventing and treating the factors that increase the risk of CPSP and related disability; and (3) to present recent empirical evidence for the efficacy of the TPS. Methods: The Toronto General Hospital TPS was specifically developed to target patients at high risk of developing CPSP. The major known risk factors for CPSP are perioperative pain, opioid use, and negative affect, including depression, anxiety, pain catastrophizing, and posttraumatic stress disorder-like symptoms. At-risk patients are identified early and provided comprehensive care by a multidisciplinary team consisting of pain physicians, advanced practice nurses, psychologists, and physical therapists. Results: Preliminary results from two nonrandomized, clinical practice-based trials indicate that TPS treatment is associated with improvements in pain, pain interference, pain catastrophizing, symptoms of anxiety and depression, and opioid use. Almost half of opioid-naïve patients and one in four opioid-experienced patients were opioid free by the 6-month point. Conclusions: These promising results suggest that the TPS benefits patients at risk of CPSP. A multicenter randomized controlled trial of the TPS in several Ontario hospitals is currently underway.

Toward a phenomic analysis of chronic postsurgical pain following cardiac surgery

Background: Despite the same surgical approach, up to 40% of patients develop chronic postsurgical pain (CPSP) following cardiac surgery, whereas the rest are chronic pain free. This variability suggests that CPSP is controlled partially through genetics, but the genes for CPSP are largely unknown.

Aims: The aim of this study was to identify potential CPSP phenotypes by comparing patients who developed CPSP following cardiac surgery vs. those who did not.

Methods: A research ethics board–approved, cross-sectional study of post–cardiac surgery pain was conducted at Toronto General Hospital from 2011 to 2015. Patients were recruited to complete a short survey of chronic pain scores and the Short-Form McGill Pain Questionnaire–2. A subset of patients completed a longer survey of eight validated pain phenotyping questionnaires and/or four psychophysical assessments. All surveys and psychophysical testing were conducted after surgery. Patients were stratified by presence of chronic pain and groups were compared using descriptive statistics.

Results: Six hundred forty-three patients completed the short form survey. The mean postsurgery assessment time was 41.5 (SD = ±25.1) months. Over a quarter (27.8%) reported CPSP at the chest as a consequence of their surgery. Of patients reporting CPSP, 46.6% reported mild pain (0–3), 35.8% reported moderate pain (4–7), and 17.6% reported severe pain (7–10) in accordance with the numerical rating scale. Patients with moderate and/or severe CPSP were younger, had a greater body mass index, and had higher anxiety sensitivity, pain catastrophizing, and somatization scores.

Conclusions: Chronic pain levels after cardiac surgery are associated with anxiety, catastrophizing, and sensory abnormalities in body parts outside the field innervated by injured nerves, indicating the presence of widespread central sensitization to incoming sensory inputs from intact nerves.

Preoperative ultrasound-guided multilevel paravertebral blocks reduce the incidence of postmastectomy chronic pain: a double-blind, placebo-controlled randomized trial

Purpose

Chronic postsurgical pain is a challenging problem after breast cancer surgery. This prospective, randomized, double-blinded, parallel-group, placebo-controlled trial was conducted to evaluate the influence of preoperative ultrasound-guided multilevel paravertebral blocks (PVBs) on chronic pain following mastectomy.

Patients and methods

One hundred eighty-four women were randomized to receive ultrasound-guided multilevel (T1-T5) PVBs with 5 mL of ropivacaine 0.5% or normal saline per level. The primary end point was the incidence of chronic pain at 3 months following mastectomy assessed by the brief pain inventory (BPI), while the secondary end points were the acute postoperative pain, the number of patients requiring rescue analgesia, postoperative nausea and vomiting (PONV), side effects, and chronic pain at 6 months after surgery assessed by the BPI.

Results

A total of 172 patients completed the study. Ultrasound-guided multilevel PVBs significantly decreased immediate postoperative pain for the first 12 hours (P<0.001). Additionally, fewer patients in the PVB group required rescue analgesia in the first 48 hours post-operatively compared to the control group (5/86 vs 28/86, OR =0.128, 95% CI: 0.047-0.351, P<0.001). No statistically significant difference was tested between the two groups (9.3% vs 17.4%, OR =0.419, 95% CI: 0.162-1.087, P=0.068) in the incidence of PONV. At 3 months, the incidence of chronic pain (BPI average pain score ≥3) was 34.5% and 51.2% (OR =0.511, 95% CI: 0.277-0.944, P=0.031) in the PVB and control groups, respectively, and at 6 months, the incidence was 22.1% and 37.2% (OR =0.479, 95% CI: 0.245-0.936, P=0.03), respectively. No complications occurred during the study.

Conclusion

This study indicated that perioperative ultrasound-guided multilevel PVBs with ropivacaine improved acute postoperative pain and decreased postmastectomy chronic pain at 3 and 6 months postoperatively.

Enrichment of Genomic Pathways Based on Differential DNA Methylation Associated With Chronic Postsurgical Pain and Anxiety in Children: A Prospective, Pilot Study

We have reported child anxiety sensitivity (Child Anxiety Sensitivity Index [CASI]) predicts chronic postsurgical pain (CPSP). Herein, we evaluated DNA methylation profiles to understand the gene-environment interactions underlying CPSP and CASI, to identify shared, enriched, genomic pathways. In 73 prospectively recruited adolescents undergoing spine fusion, preoperative CASI and pain data over 12 months after surgery were collected. DNA from the peripheral blood of evaluable subjects with (n = 16) and without CPSP (n = 40) were analyzed using MethylationEPIC arrays. We identified 637 and 2,445 differentially DNA methylated positions (DMPs) associated with CPSP and CASI, respectively (P ≤ .05). Ingenuity pathway analysis of 39 genes with DMPs for both CPSP and CASI revealed enrichment of several canonical pathways, including GABA receptor (P = .00016 for CPSP; P =.0008 for CASI) and dopamine-DARPP32 feedback in cyclic adenosine monophosphate (P = .004 for CPSP and P =.00003 for CASI) signaling. Gene-gene interaction network enrichment analysis revealed participation of pathways in cell signaling, molecular transport, metabolism, and neurologic diseases (P < 10^-8). Bioinformatic approaches to identify histone marks and transcription factor (TF) binding events underlying DMPs, showed their location in active regulatory regions in pain pathway relevant brain cells. Using Enrichr/Pinet enrichment and Library of Integrated Network-Based Cellular Signatures knockdown signatures, we identified TFs regulating genes with DMPs in association with CPSP and CASI. In conclusion, we identified epigenetically enriched pathways associated with CPSP and anxiety sensitivity in children undergoing surgery. Our findings support GABA hypofunction and the roles of the dopamine-DARPP32 pathway in emotion/reward and pain. This pilot study provides new epigenetic insights into the pathophysiology of CPSP and a basis for future studies in biomarker development and targetable interventions. PERSPECTIVE: Differential DNA methylation in regulatory genomic regions enriching shared neural pathways were associated with CPSP and CASI in adolescents undergoing spine surgery. Our findings support GABA hypofunction and the roles of the dopamine-DARPP32 pathway in emotion/reward contributing to behavioral maintenance of pain 10 to 12 months after surgery.