The neuropathic component in persistent postsurgical pain: a systematic literature review. Pain. 2013;154:95-102. [PMID: 23273105 DOI: 10.1016/j.pain.2012.09.010]

Neuropathic Pain Following Breast-conserving Surgery: A Systematic Review and Meta-Analysis

Background

Chronic pain after breast cancer surgery, affecting 25%-60% of patients, significantly impacts the survivors' quality of life. With improved survival rates, more individuals are experiencing this long-term complication. It is often overlooked that this chronic pain may stem from peripheral nerve injury, resulting in neuropathic pain characterized by burning sensations, electric shocks, and heightened sensitivity. Although neuropathic pain prevalence is reported at 24%-36% post-mastectomy, the data following breast-conserving surgery remain limited. This systematic review aimed to investigate the prevalence of neuropathic pain after breast-conserving surgery and its potential association with axillary procedures.

Methods

The electronic databases, Medline, Embase, Web of Science and Cochrane Central, were searched. Inclusion criteria were defined to include studies reporting on the prevalence of neuropathic pain following breast-conserving surgery and exploring associations with axillary procedures. A meta-analysis was performed to compute a pooled prevalence rate.

Results

Eight studies, covering 1,469 patients post-breast-conserving surgery, met the inclusion criteria. The meta-analysis revealed a pooled prevalence of 31% (95% confidence intervals [CI] 0.14-0.56) neuropathic pain among patients who underwent breast-conserving surgery. Six studies explored associations with axillary procedures; however, none suggested a correlation between axillary procedures and neuropathic pain after breast-conserving surgery.

Conclusion

This systematic review and meta-analysis indicated a pooled prevalence of 31% neuropathic pain following breast-conserving surgery of, with confidence interval ranging from 14% to 56%. The review did not provide conclusive evidence to suggest correlations between axillary procedures and neuropathic pain after breast-conserving surgery.

Chronic Postsurgical Pain

Chronic pain is a devastating condition that impacts more than 50 million adults nationwide. It can lead to chronic opioid addiction, reduced quality of life, economic collapse, divorce, homelessness, and suicide. Chronic pain associated with surgical interventions is a common, but often misunderstood and misdiagnosed condition. Understanding chronic pain and the physical, psychological, and psychosocial links to chronic postsurgical pain can help nurses identify, prevent, or better treat the condition.

Is there a role for capsaicin in cancer pain management?

PURPOSE OF REVIEW

Advances in oncological therapies have resulted in an increase in the number of patients living with and beyond cancer. The personal and societal impact of chronic pain in the survivor population represents an area of significant unmet need. Capsaicin (a TRPV1 agonist) may provide analgesia with limited systemic side effects. This review looks to summarise the most recent evidence regarding the use of capsaicin in the management of cancer pain.

RECENT FINDINGS

Various international guidelines have recently endorsed the use of high concentration capsaicin patches in the treatment of chronic painful chemotherapy induced peripheral neuropathy. Numerous studies support the use of capsaicin in the treatment of peripheral neuropathic pain. This promising data is predominantly yielded from pain secondary to herpes zoster and diabetic neuropathy, with an expanding but small evidence base for its utility in other neuropathic pains. Emerging data suggests that treatments are better tolerated and provide analgesia more rapidly when compared with systemic treatments.

SUMMARY

Whilst randomised controlled trial data in the treatment of cancer pain are lacking, recent large cohort studies, and international guidelines, support the use of high concentration capsaicin patches in a wide variety of neuropathic pain secondary to cancer treatments.

Chronic post-surgical pain after total knee arthroplasty: a narrative review

Total knee arthroplasty (TKA) is an efficacious treatment for end-stage knee osteoarthritis, often accompanied by severe postoperative pain. In certain patients, this pain can persist for over 3 months and is referred to as chronic post-surgical pain (CPSP). Postoperative persistent pain has emerged as a significant and noteworthy issue impacting patient quality of life following TKA. The etiology of CPSP after TKA is multifaceted. Peripheral or central sensitizations resulting from inflammatory reactions, nerve injury, and neurobiological mechanisms are the primary mechanisms contributing to chronic persistent pain after TKA. Preoperative, intraoperative, and postoperative factors can induce pain sensitization. Once CPSP occurs after TKA, it significantly hampers patient recovery with challenging treatment options. Currently, among the preventive and therapeutic strategies for chronic pain after TKA, it is widely believed that early comprehensive preventive treatment to prevent acute to chronic pain transition can substantially reduce the incidence of CPSP following TKA. In recent years, studies have investigated perioperative strategies aimed at reducing the occurrence of persistent pain after TKA. This article provides an overview of advancements in understanding the pathogenesis, high-risk factors, and preventive measures for chronic pain following TKA. We hope that this review will guide future research directions on CPSP after TKA while contributing to clinical perioperative pain management.

Risk factors for persistent postoperative opioid use: an entity distinct from chronic postsurgical pain

Despite a decline in opioid prescriptions over the past decade, patients commonly receive opioid analgesics as a treatment for postoperative pain in the USA. One complication that patients may experience after surgery is persistent postoperative opioid use (PPOU), or opioid use beyond the typical recovery period. Often defined as beyond 3 months postsurgery, PPOU is frequently conflated with chronic postsurgical pain (CPSP), where pain persists well after the expected healing time following surgery. This narrative review explores the distinct risk factors for each condition, their interrelation, and potential future research directions.For PPOU, major risk factors include the risky use of substances including misuse and use disorders; depression and other mental health disorders; a history of chronic pain before surgery including back pain; and certain surgical types (ie, total knee arthropathy, open cholecystectomy, total hip arthropathy). Conversely, CPSP risk factors include the type of surgery (ie, thoracic and breast surgeries), mental health conditions (particularly catastrophizing), and pain in both the preoperative and postoperative phases. Despite the overlap of some factors, studies typically employ different frameworks when examining PPOU and CPSP, with a biopsychosocial model applied for CPSP and little emphasis on an individual's social environment employed for PPOU. Additionally, existing studies predominantly rely on retrospective insurance claims data, which may not capture the full scope of risk factors.To fill gaps in understanding, investigations may prospectively assess and analyze patient-reported outcomes, implement similar frameworks, and concurrently measure both conditions to advance the scientific understanding of PPOU and CPSP.

Persistent pain after total temporomandibular joint replacement surgery: clinical characteristics, comorbidities, and risk factors

Chronic post-surgical pain (CPSP) after temporomandibular joint (TMJ) surgery is an under-recognized problem. The aim of this study was to document the characteristics of CPSP and identify patient risk factors and comorbidities associated with the development of CPSP after total TMJ replacement (TJR). This was a retrospective cohort study of patients who underwent TJR between 2000 and 2018 at Massachusetts General Hospital, Boston, USA. The primary outcome was the presence of CPSP and use of pain medications after TJR. The secondary outcome was the risk factors associated with the development of CPSP. A total 88 patients were included (79 females, 9 males). The mean follow-up was 4.2 years. Overall, 68 (77.3%) had CPSP and 20 (22.7%) had no CPSP. Of those with CPSP, 32.4% had severe pain and 45.6% continued to take pain medications. Of the 27 patients with data available on the characteristics of the pain, the majority had myofascial pain, while some developed neuropathic pain. A significant difference was noted between the CPSP and non-CPSP groups in terms of preoperative pain, smoking behavior, and use of opioids, non-steroidal anti-inflammatory drugs, muscle relaxants, and neuropathic pain medications.

Integrating mechanistic-based and classification-based concepts into perioperative pain management: an educational guide for acute pain physicians

Chronic pain begins with acute pain. Physicians tend to classify pain by duration (acute vs chronic) and mechanism (nociceptive, neuropathic and nociplastic). Although this taxonomy may facilitate diagnosis and documentation, such categories are to some degree arbitrary constructs, with significant overlap in terms of mechanisms and treatments. In clinical practice, there are myriad different definitions for chronic pain and a substantial portion of chronic pain involves mixed phenotypes. Classification of pain based on acuity and mechanisms informs management at all levels and constitutes a critical part of guidelines and treatment for chronic pain care. Yet specialty care is often siloed, with advances in understanding lagging years behind in some areas in which these developments should be at the forefront of clinical practice. For example, in perioperative pain management, enhanced recovery protocols are not standardized and tend to drive treatment without consideration of mechanisms, which in many cases may be incongruent with personalized medicine and mechanism-based treatment. In this educational document, we discuss mechanisms and classification of pain as it pertains to commonly performed surgical procedures. Our goal is to provide a clinical reference for the acute pain physician to facilitate pain management decision-making (both diagnosis and therapy) in the perioperative period.

Chronic Postsurgical Pain Following Lung Transplantation: Characteristics, Risk Factors, Treatment, and Prevention: A Narrative Review

Chronic pain after lung transplantation (LTx) can substantially reduce quality of life (QoL), yet current consensus guidelines say little about how to prevent or manage it. Research on pain after LTx has tended to focus on acute rather than chronic pain, and it has not extensively examined the factors associated with onset or resolution of chronic pain, which differ from factors influencing chronic pain after general thoracic surgery. This narrative review explores what is known about the epidemiology and risk factors of chronic pain after LTx, as well as effective ways to treat or prevent it. The review identifies key questions and issues that should be the focus of future research.

Effects of Ultrasound-Guided Thoracic Paravertebral Nerve Block Combined with Perineural or IV Dexmedetomidine on Acute and Chronic Pain After Thoracoscopic Resection of Lung Lesions: A Double-Blind Randomized Trial

Background

Thoracic paravertebral block (TPVB) analgesia can be prolonged by local anesthetic adjuvants such as dexmedetomidine. This study aimed to evaluate the two administration routes of dexmedetomidine on acute pain and chronic neuropathic pain (NeuP) prevention compared with no dexmedetomidine.

Methods

A total of 216 patients were randomized to receive TPVB using 0.4% ropivacaine alone (R Group), with perineural dexmedetomidine 0.5 μg·kg-1 (RD0.5 Group) or 1.0 μg·kg-1 (RD1.0 Group), or intravenous (IV) dexmedetomidine 0.5 μg·kg-1·h-1 (RDiv Group). The primary outcome was the incidence of chronic NeuP, defined as a Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) pain score > 12 points at 3-month after surgery.

Results

(1) For the primary outcome, RD0.5 Group and RD1.0 Group demonstrated a decreased incidence of chronic NeuP at 3-month after surgery; (2) Compared with R Group, RDiv Group, RD0.5 Group, and RD1.0 Group can reduce VAS scores at rest and movement and Prince-Henry Pain scores at 12 and 24-h after surgery, the consumption of oral morphine equivalent (OME) and improve QOD-15 at POD1; (3) Compared with RDiv Group, RD0.5 Group and RD1.0 Group can reduce VAS scores at rest and movement and Prince-Henry Pain scores at 12 and 24-h after surgery, the consumption of postoperative OME and improve QOD-15 at POD1; (4) Compared with RD0.5 Group, RD1.0 Group effectively reduced VAS scores at rest at 12 and 24-h after surgery, VAS scores in movement and Prince-Henry Pain scores at 12-h after surgery. However, RD1.0 Group showed an increased incidence of drowsiness.

Conclusion

Perineural or IV dexmedetomidine are similarly effective in reducing acute pain, but only perineural dexmedetomidine reduced chronic NeuP. Moreover, considering postoperative complications such as drowsiness, perineural dexmedetomidine (0.5 μg·kg-1) may be a more appropriate choice.

Clinical Trial Registration

Chinese Clinical Trial Registry (ChiCTR2200058982).

Peripheral nerve stimulation for saphenous neuralgia

BACKGROUND

Injury to saphenous nerve branches is frequent during knee surgery and can result in chronic pain. This saphenous neuralgia remains challenging to treat. Peripheral nerve stimulation (PNS) is a new potential non-pharmacologic treatment option. We present our outcomes experience using this technology in 12 patients.

METHODS

We retrospectively reviewed PNS placement for saphenous neuralgia between 2000 and 2022 at a single institution. Demographic information was collected as well as response to the device. Four-question short-form Patient-Reported Outcome Measurement Information System (PROMIS) Scores were collected before and 2 weeks, 6 weeks, and 6 months postprocedure. Specific scores included pain interference and behavior, functional mobility, depression, anxiety, and sleep impairment. Change in pain interference measured by the short-form PROMIS tool at 6 months was chosen as the primary outcome.

RESULTS

Twelve patients met inclusion criteria, with 10 patients having the full 6-month follow-up. In these 10 patients, the mean change from baseline in the short-form adjusted pain interference score (greater difference means improved pain) at 6 months was 5.8 (SD 6.5). Among all patients, average follow-up was 11.5 months (range 3-35 months). Most patients' symptoms developed after knee surgery (84%). Prior to PNS, patients underwent other treatments including cryoablation (8%), radiofrequency ablation (16%), saphenous neurectomy (16%), or surgical release of adjacent nerves (25%). Ten patients (83%) reported any improvement in symptoms while two reported no benefit. Complications occurred in four patients (33%). Two patients had the device removed and a third discontinued use. PROMIS Scores for pain, functional mobility, mood, and sleep impairment all improved.

DISCUSSION

Limited effective treatments exist for saphenous neuralgia. Our case series demonstrates the potential of PNS as a treatment for saphenous neuralgia. Comparative effectiveness studies are warranted to assess whether our effect size is clinically relevant.

Increased risk of persistent neuropathic pain after traumatic nerve injury and surgery for carriers of a human leukocyte antigen haplotype

ABSTRACT

It is not known why some patients develop persistent pain after nerve trauma while others do not. Among multiple risk factors for the development of persistent posttrauma and postsurgical pain, a neuropathic mechanism due to iatrogenic nerve lesion has been proposed as the major cause of these conditions. Because there is some evidence that the human leukocyte antigen (HLA) system plays a role in persistent postsurgical pain, this study aimed to identify the genetic risk factors, specifically among HLA loci, associated with chronic neuropathic pain after traumatic nerve injuries and surgery in the upper extremities. Blood samples were taken to investigate the contribution of HLA alleles (ie, HLA-A, HLA-B, HLA-DRB1, HLA-DQB1, and HLA-DPB1) in a group of patients with persistent neuropathic pain (n = 70) and a group of patients with neuropathy without pain (n = 61). All subjects had intraoperatively verified nerve damage in the upper extremity. They underwent bedside clinical neurological examination to identify the neuropathic pain component according to the present grading system of neuropathic pain. Statistical analyses on the allele and haplotype were conducted using the BIGDAWG package. We found that the HLA haplotype A*02:01-B*15:01-C*03:04-DRB1*04:01-DQB1*03:02 was associated with an increased risk of developing persistent neuropathic pain in the upper extremity (OR = 9.31 [95% CI 1.28-406.45], P < 0.05). No significant associations were found on an allele level when correcting for multiple testing. Further studies are needed to investigate whether this association is on a haplotypic level or if certain alleles may be causing the association.

Chronic postsurgical pain: A European survey

BACKGROUND

Chronic postsurgical pain (CPSP) is a clinical problem, and large prospective studies are needed to determine its incidence, characteristics, and risk factors.

OBJECTIVE

To find predictive factors for CPSP in an international survey.

DESIGN

Observational study.

SETTING

Multicentre European prospective observational trial.

PATIENTS

Patients undergoing breast cancer surgery, sternotomy, endometriosis surgery, or total knee arthroplasty (TKA).

METHOD

Standardised questionnaires were completed by the patients at 1, 3, and 7 days, and at 1, 3, and 6 months after surgery, with follow-up via E-mail, telephone, or interview.

MAIN OUTCOME MEASURE

The primary goal of NIT-1 was to propose a scoring system to predict those patient likely to have CPSP at 6 months after surgery.

RESULTS

A total of 3297 patients were included from 18 hospitals across Europe and 2494 patients were followed-up for 6 months. The mean incidence of CPSP at 6 months was 10.5%, with variations depending on the type of surgery: sternotomy 6.9%, breast surgery 7.4%, TKA 12.9%, endometriosis 16.2%. At 6 months, neuropathic characteristics were frequent for all types of surgery: sternotomy 33.3%, breast surgery 67.6%, TKA 42.4%, endometriosis 41.4%. One-third of patients experienced CPSP at both 3 and 6 months. Pre-operative pain was frequent for TKA (leg pain) and endometriosis (abdomen) and its frequency and intensity were reduced after surgery. Severe CPSP and a neuropathic pain component decreased psychological and functional wellbeing as well as quality of life. No overarching CPSP risk factors were identified.

CONCLUSION

Unfortunately, our findings do not offer a new CPSP predictive score. However, we present reliable new data on the incidence, characteristics, and consequences of CPSP from a large European survey. Interesting new data on the time course of CPSP, its neuropathic pain component, and CPSP after endometriosis surgery generate new hypotheses but need to be confirmed by further research.

TRIAL REGISTRATION

clinicaltrials.gov ID: NCT03834922.

Postoperative Pain Following Eye Enucleation: A Prospective Observational Study

Background and Objectives: Enucleation of an eye is the most invasive procedure in ophthalmologic surgery. It can be the result of various diseases (malignant/chronic/trauma/infection) and is nevertheless relatively rare, but leads to the loss of a strongly innervated neuronal organ. This study systematically evaluates postoperative pain levels following enucleation of the eye globe. Materials and Methods: This prospective single-center study enrolled twenty-four patients undergoing enucleation of the eye globe. Perioperatively all patients completed (preoperative day, day of surgery, 1st, 2nd, and 3rd day following surgery) standardized questionnaires concerning their pain experience and treatment-related side-effects (internal protocol, QUIPS, painDETECT®). Patients received usual pain therapy in an unstandardized individual manner. Results: Preoperatively, mean average pain intensity of all included patients was 3.29 ± 2.46 (range, 0-8), 3.29 ± 3.24 (range, 0-8) on the day of surgery, 4.67 ± 1.90 (range, 2-10) on day 1, 3.25 ± 1.39 (range, 1-6) on day 2, and 2.71 ± 1.30 (range, 1-6) on day 3 after surgery. Mean maximum pain intensity was 4.71 ± 3.28 (range, 0-10) preoperatively, 4.04 ± 3.78 (range, 0-10) on the day of surgery, 5.75 ± 2.01 (range, 2-10) on day 1, 4.25 ± 1.89 (range, 2-10) on day 2, and 3.88 ± 1.54 (range, 2-8) on day 3 after surgery. Nineteen patients (79.2%) stated that they would have preferred more pain therapy. Conclusions: Patients undergoing eye enucleation report pain sensations in need of intervention in this university hospital. Thus, effective standardized pain treatment concepts are now a high priority to be established in an interdisciplinary manner containing standardized regimens and continuous regional procedures. Awareness of this problem in the medical team should be sharpened through targeted training and information.

Chronic pain after breast surgery: incidence, risk factors and impact on quality of life

INTRODUCTION AND OBJECTIVES

Breast cancer is the most frequently diagnosed malignancy, and chronic pain after breast surgery (CPBS) is an increasingly recognized therapy-related problem. We evaluated CPBS incidence, characteristics, associated factors, and impact on patient quality of life (QoL).

MATERIALS AND METHODS

Six-month observational prospective study conducted in patients undergoing breast surgery in a tertiary university hospital. Data were collected using several questionnaires: Pain Catastrophizing Scale, Brief Pain Inventory-Short Form, Douleur Neuropathique 4 Questionnaire, and European Organization for Research and Treatment of Cancer Quality of Life Questionnaire and its Breast Cancer Module.

RESULTS

A total of 112 patients completed the study. Approximately, one third (34.8%) developed CPBS, and almost all with potentially neuropathic pain. CPBS interfered with patients' daily life and reduced their QoL. Diabetes (p = 0.028), catastrophizing (p = 0.042), and acute postoperative pain severity (p < 0.001) were associated with CPBS.

CONCLUSIONS

This study broadens our understanding of CPBS and shows the impact of this syndrome. Healthcare workers need to be aware of CPBS and take steps to prevent and treat it, and provide patients with adequate information.

Perioperative Pain Management for Thoracic Surgery: A Multi-Layered Approach

Cardiothoracic surgeries frequently pose unique challenges in the management of perioperative acute pain that require a multifaceted and personalized approach in order to optimize patient outcomes. This article discusses various analgesic strategies including regional anesthesia techniques such as thoracic epidurals, erector spinae plane blocks, and serratus anterior plane blocks and underscores the significance of perioperative multimodal medications, while providing nuanced recommendations for their use. This article further attempts to provide evidence for the efficacy of the different modalities and compares the effectiveness of the choice of analgesia. The roles of Acute Pain Services (APS) and Transitional Pain Services (TPS) in mitigating opioid dependence and chronic postsurgical pain are also discussed. Precision medicine is also presented as a potential way to offer a patient tailored analgesic strategy. Supported by various randomized controlled trials and meta-analyses, the article concludes that an integrated, patient-specific approach encompassing regional anesthesia and multimodal medications, while also utilizing the services of the Acute Pain Service can help to enhance pain management outcomes in cardiothoracic surgery.

Chronic post-surgical pain following gastrointestinal surgery: Protocol for a scoping review

BACKGROUND

Chronic post-surgical pain (CPSP) significantly impacts people's lives, affecting both socioeconomic aspects as well as their rehabilitation after surgery. Yet, CPSP remains an under-researched field. The prevalence varies depending on type of surgery, which highlights the importance of surgery-specific research. This scoping review aims to investigate CPSP following gastrointestinal surgery in order to map out incidences, risk factors, and impact on quality of life (QoL) as well as identify gaps in research.

METHODS

The planned review will follow the Preferred Reporting Items for Systematic review and Meta-Analyses (PRISMA) for Scoping Review guidelines. A search strategy will be carried out in major peer-reviewed databases and grey literature will be sought and identified. We will include original studies assessing CPSP after gastrointestinal surgery, with the exception of hernia surgery. We will chart data regarding trial characteristics, patient demographic, surgical diagnosis, risk factors, follow-up times, pain definitions and evaluations as well as impact on QoL.

RESULTS

We will present the included studies with a narrative summary, supplemented with descriptive statistics of the quantitative data if appropriate.

CONCLUSION

The planned scoping review will map out the current evidence about CPSP in adults following gastrointestinal surgery. We will identify gaps in research that can support the development of further research into CPSP after gastrointestinal surgery.

Effect of Remifentanil on Acute and Chronic Postsurgical Pain in Patients Undergoing Cardiac Surgery: A Systematic Review and Meta-analysis

OBJECTIVES

Our purpose was to explore the effect of remifentanil on acute and chronic postsurgical pain after cardiac surgery.

MATERIALS AND METHODS

Randomized controlled trials were retrieved from electronic databases, such as PubMed, Cochrane Library, China National Knowledge Internet databases, Scopus, and Web of Science. A systematic review, meta-analysis, and trial sequential analysis (TSA) were performed. Basic information and outcomes were extracted from the included studies. The primary outcome was chronic postsurgical pain. Secondary outcomes were scores of postsurgical pain and morphine consumption within 24 hours after cardiac surgery. Risk of bias (ROB) assessment was based on the Cochrane ROB tool version 2. The overall quality of the evidence was rated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system.

RESULTS

Seven studies consisting of 658 patients were enrolled in the meta-analysis. A single study had a high ROB and 2 studies had a moderate ROB. The incidence of chronic postsurgical pain (4 studies [415 patients]; risk ratio: 1.02 [95% CI: 0.53 to 1.95]; P = 0.95; I2 = 59%; TSA-adjusted CI: 0.78 to 1.20) and the postsurgical pain score (2 studies [196 patients]; mean difference: 0.09 [95% CI: -0.36 to 0.55]; P = 0.69; I2 = 0%; TSA-adjusted CI: -0.36 to 0.55) were not statistically different between the 2 groups. However, morphine consumption (6 studies [569 patients]; mean difference: 6.94 [95% CI: 3.65 to 10.22]; P < 0.01; I2 = 0%; TSA-adjusted CI: 0.00 to 0.49) was higher in the remifentanil group than in the control group.

CONCLUSION

There was not enough evidence to prove that remifentanil can increase the incidence of chronic postsurgical pain after cardiac surgery, but interestingly, the results tended to support a trend toward increased complications in the intervention group. However, there was moderate certainty evidence that the use of remifentanil increases the consumption of morphine for analgesia, and more direct comparison trials are needed to inform clinical decision-making with greater confidence.

Effect and safety profile of topical lidocaine on post-surgical neuropathic pain and quality of life: A systematic review and meta-analysis

STUDY OBJECTIVE

Post-surgical chronic pain with a neuropathic component is usually more severe and leads to worse quality of life. We conducted this systematic review to examine the evidence of topical lidocaine for post-surgical neuropathic pain.

DESIGN

Systematic review with meta-analysis.

SETTING

Published randomized controlled trials (RCTs) comparing topical lidocaine with placebo or no topical lidocaine for post-surgical neuropathic pain.

PATIENTS

Seven RCTs including 585 patients.

INTERVENTIONS

We systematically searched databases for randomized controlled trials (RCTs) investigating the effect and safety outcomes of topical lidocaine compared with placebo or no intervention.

MEASUREMENTS

We conducted meta-analyses to evaluate the effect of topical lidocaine on pain intensity, adverse events, and quality of life. Standardized mean difference (SMD) and relative risk (RR) with 95% CIs were effect measures for continuous and dichotomous outcomes, respectively. We assessed the risk of bias of included trials and the certainty of evidence for each outcome.

MAIN RESULTS

Our review included 7 studies with 585 participants. There is moderate certainty evidence that topical lidocaine may increase the likelihood of global pain relief, with a relative risk (RR) of 1.98 (95% confidence interval (CI): 1.04, 3.76; I2 = 70%, P = 0.04). Low certainty evidence suggested topical lidocaine may lead to more reduction in pain intensity (SMD: -0.70; 95% confidence interval: -1.46, 0.06; I2 = 93%, P = 0.07). High certainty evidence showed that topical lidocaine did not increase the adverse event risk (RR: 1.04; 95% CI: 0.93, 1.16; I2 = 0%, P = 0.51).

CONCLUSIONS

Topical lidocaine may lead to pain relief and is safe to use for patient with post-surgical pain, though its impact on quality of life is unclear. This review supports the use of topical lidocaine for patients with post-surgical pain, and reveals the evidence gap in topical lidocaine use. (Registration: PROSPERO CRD42021294100).

Prevalence and Risk Factors for Chronic Postsurgical Pain After Thoracic Surgery: A Prospective Cohort Study

OBJECTIVE

Thoracic surgery is associated with one of the highest rates of chronic postsurgical pain (CPSP) among all surgical subtypes. Chronic postsurgical pain carries significant medical, psychological, and economic consequences, and further interventions are needed to prevent its development. This study aimed to determine the prevalence, characteristics, and risk factors associated with CPSP after thoracic surgery.

DESIGN

A prospective cohort study.

SETTING

Single-center tertiary care hospital.

PARTICIPANTS

This study included 285 adult patients who underwent thoracic surgery at Toronto General Hospital in Toronto, Canada, between 2012 and 2020.

MEASUREMENTS AND MAIN RESULTS

Demographic, psychological, and clinical data were collected perioperatively, and follow-up evaluations were administered at 3, 6, and 12 months after surgery to assess CPSP. Chronic postsurgical pain was reported in 32.4%, 25.4%, and 18.2% of patients at 3, 6, and 12 months postoperatively, respectively. Average CPSP pain intensity was rated to be 3.37 (SD 1.82) at 3 months. Features of neuropathic pain were present in 48.7% of patients with CPSP at 3 months and 71% at 1 year. Multivariate logistic regression models indicated that independent predictors for CPSP at 3 months were scores on the Hospital Anxiety and Depression Scale (adjusted odds ratio [aOR] of 1.07, 95% CI of 1.02 to 1.14, p = 0.012) and acute postoperative pain (aOR of 2.75, 95% CI of 1.19 to 6.36, p = 0.018).

INTERVENTIONS

None.

CONCLUSIONS

Approximately 1 in 3 patients will continue to have pain at 3 months after surgery, with a large proportion reporting neuropathic features. Risk factors for pain at 3 months may include preoperative anxiety and depression and acute postoperative pain.

How to Modulate Peripheral and Central Nervous System to Treat Acute Postoperative Pain and Prevent Pain Persistence

Chronic postoperative pain (CPSP) is a major issue after surgery, which may impact on patient's quality of life. Traditionally, CPSP is believed to rely on maladaptive hyperalgesia and risk factors have been identified that predispose to CPSP, including acute postoperative pain. Despite new models of prediction are emerging, acute pain is still a modifiable factor that can be challenged with perioperative analgesic strategies. In this review we present the issue of CPSP, focusing on molecular mechanism underlying the development of acute and chronic hyperalgesia. Also, we focus on how perioperative strategies can impact directly or indirectly (by reducing postoperative pain intensity) on the development of CPSP.

The Impact of Dorsal Root Ganglion Stimulation on Pain Levels and Functionality in Patients With Chronic Postsurgical Knee Pain

BACKGROUND

Chronic postsurgical pain is a considerable source of disabling neuropathic pain. Rates of knee replacement surgeries are increasing, and many patients report chronic postsurgical pain in their wake. When conventional therapies prove ineffective, neuromodulation options such as dorsal root ganglion stimulation (DRGS) may be used. However, little is known about the effect of DRGS on improvements in quantitative functional outcome parameters.

MATERIALS AND METHODS

In a prospective observational study at two pain centers, patients with chronic postsurgical knee pain underwent implantation with a DRGS system after an interdisciplinary multimodal pain program. Ratings of pain, mood, quality of life, and function were captured at baseline and through 12 months of treatment. Quantitative measures (range of motion, walking distance, and pain medication usage) were also recorded.

RESULTS

Visual analog scale ratings of pain decreased from 8.6 to 3.0 (p < 0.0001; N = 11), and other pain measures agreed. Quality of life on the 36-Item Short Form Health Survey questionnaire improved from 69.3 to 87.6 (p < 0.0001), whereas the improvement in depression ratings was nonsignificant. International Knee Documentation Committee questionnaire ratings of function improved from 27.7 to 51.7 (p < 0.0001), which aligned with other functional measures. On average, knee range of motion improved by 24.5°, and walking distance dramatically increased from 125 meters to 1481. Cessation of opioids, antidepressants, and/or anticonvulsants was achieved by 73% of participants.

CONCLUSIONS

Both subjective-based questionnaire and quantitative examination-based variables were in broad agreement on the value of DRGS in improving functionality and chronic postsurgical pain in the knee. Although this finding is limited by the small sample size, this intervention may have utility in the many cases in which pain becomes problematic after orthopedic knee surgery.

The role of neuroinflammation in the transition of acute to chronic pain and the opioid-induced hyperalgesia and tolerance

Current evidence suggests that activation of glial and immune cells leads to increased production of proinflammatory mediators, creating a neuroinflammatory state. Neuroinflammation has been proven to be a fundamental mechanism in the genesis of acute pain and its transition to neuropathic and chronic pain. A noxious event that stimulates peripheral afferent nerve fibers may also activate pronociceptive receptors situated at the dorsal root ganglion and dorsal horn of the spinal cord, as well as peripheral glial cells, setting off the so-called peripheral sensitization and spreading neuroinflammation to the brain. Once activated, microglia produce cytokines, chemokines, and neuropeptides that can increase the sensitivity and firing properties of second-order neurons, upregulating the signaling of nociceptive information to the cerebral cortex. This process, known as central sensitization, is crucial for chronification of acute pain. Immune-neuronal interactions are also implicated in the lesser-known complex regulatory relationship between pain and opioids. Current evidence suggests that activated immune and glial cells can alter neuronal function, induce, and maintain pathological pain, and disrupt the analgesic effects of opioid drugs by contributing to the development of tolerance and dependence, even causing paradoxical hyperalgesia. Such alterations may occur when the neuronal environment is impacted by trauma, inflammation, and immune-derived molecules, or when opioids induce proinflammatory glial activation. Hence, understanding these intricate interactions may help in managing pain signaling and opioid efficacy beyond the classical pharmacological approach.

Mechanisms inherent in acute-to-chronic pain after surgery - risk, diagnostic, predictive, and prognostic factors

PURPOSE OF REVIEW

Pain is an expected consequence of a surgery, but it is far from being well controlled. One major complication of acute pain is its risk of persistency beyond healing. This so-called chronic post-surgical pain (CPSP) is defined as new or increased pain due to surgery that lasts for at least 3 months after surgery. CPSP is frequent, underlies a complex bio-psycho-social process and constitutes an important socioeconomic challenge with significant impact on patients' quality of life. Its importance has been recognized by its inclusion in the eleventh version of the ICD (International Classification of Diseases).

RECENT FINDINGS

Evidence for most pharmacological and non-pharmacological interventions preventing CPSP is inconsistent. Identification of associated patient-related factors, such as psychosocial aspects, comorbidities, surgical factors, pain trajectories, or biomarkers may allow stratification and selection of treatment options based on underlying individual mechanisms. Consequently, the identification of patients at risk and implementation of individually tailored, preventive, multimodal treatment to reduce the risk of transition from acute to chronic pain is facilitated.

SUMMARY

This review will give an update on current knowledge on mechanism-based risk, prognostic and predictive factors for CPSP in adults, and preventive and therapeutic approaches, and how to use them for patient stratification in the future.

Retraction speed and chronic poststernotomy pain: A randomized controlled trial

OBJECTIVES

Approximately 30% of patients develop chronic poststernotomy pain (CPSP) following cardiac surgery with sternal retraction. Risk factors have been described but no causal determinants identified. Investigators hypothesized that opening the sternum slowly would impart less force (and thereby less nerve/tissue damage) and translate to a reduced incidence of CPSP. The main objectives were to determine whether or not slower sternal retraction would reduce the incidence of CPSP and improve health-related quality of life.

METHODS

Patients undergoing coronary artery bypass graft surgery were recruited to this randomized controlled trial. Patients were randomized to slow or standard retraction (ie, sternum opened over 15 minutes vs 30 seconds, respectively). Although the anesthesiologist and surgeon were aware of the randomization, the patients, assessors, and postoperative nursing staff remained blinded. Sternotomy pain and analgesics were measured in hospital. At 3, 6, and 12 months postoperatively, all patients completed the Medical Outcomes Survey Short Form and reported on CPSP and complications requiring rehospitalization. Thirty-day rehospitalizations and mortality were recorded.

RESULTS

In total, 326 patients consented to participate and 313 were randomized to slow (n = 159) versus standard retraction (n = 154). No clinically relevant differences were detected in acute pain, analgesic consumption, or the incidence of CPSP or health-related quality of life. Although the slow group had significantly more hospitalizations at 3 and 12 months postoperatively, the reasons were unrelated to retraction speed. No differences were observed in 30-day rehospitalizations or mortality.

CONCLUSIONS

All outcomes were consistent with previous reports, but no clinically significant differences were observed with retraction speed.

Pain management after thoracic surgery or chest trauma

Accidental or surgically induced thoracic trauma is responsible for significant pain that can impact patient outcomes. One of the main objectives of its pain management is to promote effective coughing and early mobilization to reduce atelectasis and ventilation disorders induced by pulmonary contusion. The incidence of chronic pain can affect more than 35% of patients after both thoracotomy and thoracoscopy as well as after chest trauma. As the severity of acute pain is associated with the incidence of chronic pain, early and effective pain management is very important. In this narrative review, we propose to detail systemic and regional analgesia techniques to minimize postoperative pain, while reducing transitional pain, surgical stress response and opioid side effects. We provide the reader with practical recommendations based on both literature and clinical practice experience in a referral level III thoracic trauma center.

Dorsal Root Ganglion Stimulation to Treat Chronic Shoulder Pain: A Case Report

A 67-year-old man presented with severe 9 of 10 intractable pain of the left shoulder joint after arthroplasty and revision surgeries, with associated weakness, atrophy, and limited range of motion in all directions. Dorsal root ganglion stimulation (DRG-S) at the left C4, C5, and C6 levels was used after failed conservative and interventional measures, resulting in significant improvement in pain, function, and quality of life measures through 6 months postimplantation. Larger studies should examine if DRG-S is effective in treating chronic arthritic joint pain as well as chronic postsurgical pain of the shoulder that is not predominantly neuropathic.

The hidden impact of neuropathic pain after surgical fixation of wrist, hip, and ankle fractures: A cross-sectional retrospective study evaluating its prevalence and risk factors

BACKGROUND

Dysesthesia, electrical and burning sensations, in addition to allodynia are frequent symptoms of neuropathic pain. Despite the high frequency, scientific data on the development of neuropathic pain after surgery for fracture fixation are scarce. The goal of the present study was to determine the prevalence, risk factors, and evaluate potential associations among neuropathic pain, pain intensity, sociodemographic, and clinical variables after wrist, hip, and ankle fracture fixation.

METHODS

A cross-sectional retrospective study involving a cohort of 166 patients who underwent surgery for distal radius, proximal femur, malleolar fracture fixation was performed. Neuropathic pain was assessed one year after fracture fixation using the Doleur Neuropathique Questionnaire (DN4).

RESULTS

The incidence of neuropathic pain in our sample was 49 (29.5%). Predictors for the development of neuropathic pain included patients with a high body mass index (BMI), female gender, diabetes mellitus, long-term use of analgesics (especially using pain-modulating medication), patients who presented some fracture-related complication during the course of the treatment, who had limitations for daily activity, and who were away from work due to chronic pain.

CONCLUSION

In our study, neuropathic pain after wrist, hip, and ankle fracture fixation was prevalent and associated with higher BMI values and amount of medication, in addition to higher proportions of female sex, absence from work, DM, limitation for daily activities, postoperative complications, and use of pain modulating medications.

Resilience to Pain-Related Depression in σ1 Receptor Knockout Mice Is Associated with the Reversal of Pain-Induced Brain Changes in Affect-Related Genes

Mice lacking the σ1 receptor chaperone (σ1R-/-) are resilient to depressive-like behaviors secondary to neuropathic pain. Examining the resilience's brain mechanisms could help develop conceptually novel therapeutic strategies. We explored the diminished motivation for a natural reinforcer (white chocolate) in the partial sciatic nerve ligation (PSNL) model in wild-type (WT) and σ1R-/- mice. In the same mice, we performed a comprehensive reverse transcription quantitative PCR (qPCR) analysis across ten brain regions of seven genes implicated in pain regulation and associated affective disorders, such as anxiety and depression. PSNL induced anhedonic-like behavior in WT but not in σ1R-/- mice. In WT mice, PSNL up-regulated dopamine transporter (DAT) and its rate-limiting enzyme, tyrosine hydroxylase (Th), in the ventral tegmental area (VTA) and periaqueductal gray (PAG) as well as the serotonin transporters (SERT) and its rate-limiting enzyme tryptophan hydroxylase 2 (Tph2) in VTA. In addition, μ-opioid receptor (MOR) and σ1R were up-regulated in PAG, and MOR was also elevated in the somatosensory cortex (SS) but down-regulated in the striatum (STR). Finally, increased BDNF was found in the medial prefrontal cortex (mPFC) and hypothalamus (HPT). Sham surgery also produced PSNL-like expression changes in VTA, HPT, and STR. Genetic deletion of the σ1R in mice submitted to PSNL or sham surgery prevented changes in the expression of most of these genes. σ1R is critically involved in the supraspinal gene expression changes produced by PSNL and sham surgery. The changes in gene expression observed in WT mice may be related to pain-related depression, and the absence of these changes observed in σ1R-/- mice may be related to resilience.

Prognostic models for chronic postsurgical pain-Current developments, trends, and challenges

PURPOSE OF REVIEW

Prognostic models for chronic postsurgical pain (CPSP) aim to predict the likelihood for development and severity of CPSP in individual patients undergoing surgical procedures. Such models might provide valuable information for healthcare providers, allowing them to identify patients at higher risk and implement targeted interventions to prevent or manage CPSP effectively. This review discusses the latest developments of prognostic models for CPSP, their challenges, limitations, and future directions.

RECENT FINDINGS

Numerous studies have been conducted aiming to develop prognostic models for CPSP using various perioperative factors. These include patient-related factors like demographic variables, preexisting pain conditions, psychosocial aspects, procedure-specific characteristics, perioperative analgesic strategies, postoperative complications and, as indicated most recently, biomarkers. Model generation, however, varies and performance and accuracy differ between prognostic models for several reasons and validation of models is rather scarce.

SUMMARY

Precise methodology of prognostic model development needs advancements in the field of CPSP. Development of more accurate, validated and refined models in large-scale cohorts is needed to improve reliability and applicability in clinical practice and validation studies are necessary to further refine and improve the performance of prognostic models for CPSP.

Long-term tactile hypersensitivity after nerve crush injury in mice is characterized by the persistence of intact sensory axons

ABSTRACT

Traumatic peripheral nerve injuries are at high risk of neuropathic pain for which novel effective therapies are urgently needed. Preclinical models of neuropathic pain typically involve irreversible ligation and/or nerve transection (neurotmesis). However, translation of findings to the clinic has so far been unsuccessful, raising questions on injury model validity and clinically relevance. Traumatic nerve injuries seen in the clinic commonly result in axonotmesis (ie, crush), yet the neuropathic phenotype of "painful" nerve crush injuries remains poorly understood. We report the neuropathology and sensory symptoms of a focal nerve crush injury using custom-modified hemostats resulting in either complete ("full") or incomplete ("partial") axonotmesis in adult mice. Assays of thermal and mechanically evoked pain-like behavior were paralleled by transmission electron microscopy, immunohistochemistry, and anatomical tracing of the peripheral nerve. In both crush models, motor function was equally affected early after injury; by contrast, partial crush of the nerve resulted in the early return of pinprick sensitivity, followed by a transient thermal and chronic tactile hypersensitivity of the affected hind paw, which was not observed after a full crush injury. The partially crushed nerve was characterized by the sparing of small-diameter myelinated axons and intraepidermal nerve fibers, fewer dorsal root ganglia expressing the injury marker activating transcription factor 3, and lower serum levels of neurofilament light chain. By day 30, axons showed signs of reduced myelin thickness. In summary, the escape of small-diameter axons from Wallerian degeneration is likely a determinant of chronic pain pathophysiology distinct from the general response to complete nerve injury.

Immediate postoperative topical lidocaine gel for the treatment of eye pain following corneal abrasion in descemet membrane endothelial keratoplasty (DMEK) under general anaesthesia: a pilot retrospective analysis

BACKGROUND

Patients undergoing corneal abrasion as part of Descemet membrane endothelial keratoplasty (DMEK) under general anesthesia suffer from early burning pain postoperatively. This pain appears to be poorly treatable with systemic analgesics. This study aims to evaluate postoperative pain management using topical lidocaine gel after DMEK with iatrogenic corneal abrasion.

METHODS

Retrospective analysis of 28 consecutive patients undergoing DMEK with corneal abrasion from October 19, 2021, to November 12, 2021, at a German university hospital. Patients during week 1 and 2 received peri-operative standard pain treatment (cohort S) and additional local lidocaine gel during week 3 and 4 immediately postoperatively (cohort L).

RESULTS

13 patients were included in cohort S and 15 patients in cohort L. At awakening all patients (100%) in cohort S reported burning pain, and six of 15 patients (40%) in cohort L reported burning pain. Burning pain scores were significantly lower in cohort L (p < 0.001 at awakening, p < 0.001 at 10 min, p < 0.001 at 20 min, p < 0.001 at 30 min, p = 0.007 at 40 min after awakening, and p < 0.001 at leaving recovery room). No significant differences between cohort S and cohort L were detected concerning surgical outcome during 1-month-follow-up (p = 0.901 for best corrected visual acuity).

CONCLUSION

Patients undergoing DMEK with corneal abrasion suffer significant pain in the recovery room. A single dose of topic lidocaine gel reduces the early postoperative burning pain sufficiently and does not affect the surgical outcome.

Implanting the proximal stump of the nerve in the inguinal fat tissue as an effective technique to avoid inguinal pain after accidental inguinal nerve transection: Case report

INTRODUCTION

A neuroma can occur after the inguinal nerve is injured by accident during the inguinal repair surgery. The neuroma, formed at the tip of the proximal site of the transected inguinal nerve, promotes the growth of neuroma fascicles and causes a painful/tingling sensation if tapped or pressed on the inguinal area.

PRESENTATION OF CASE

To decrease the neuropathic pain caused by accidental transection of the inguinal nerve, the proximal stump of the transected inguinal nerve is implanted into the subcutan fat tissue in the inguinal area through a different opening away from the incision of the external oblique aponeurosis.

DISCUSSION

The incapability of white adipose or fat tissue in promoting nerve fiber regeneration is due to the absence of neurotrophic factors in the inguinal subcutaneous white fat tissue. The white fat tissue is not invaded by neuroma fascicles as it usually occurs in brown fat tissues or other connective tissues where the neurotrophic factor is abundant. In the manuscript, we reported 2 cases of accidental transections of inguinal nerve in open hernia repair surgery, the proximal stump of the transected nerve was implanted in the inguinal-subcutan fat tissue. No neuropathic pain has been reported by these patients since 2015 and 2017, respectively. The hypoesthetic on the inguinal area was the only sensation felt by the patients.

CONCLUSION

The technique of penetrating the proximal stump out of the transected inguinal nerve through the external oblique aponeurosis and implanting it into the subcutan inguinal fat tissue is an effective technique to avoid neuropathic pain.

Transitional Pain Medicine; New Era, New Opportunities, and New Journey

Chronic postsurgical pain (CPSP), also known as persistent postsurgical pain (PPSP), is pain that develops or increases in intensity after a surgical procedure and lasts more than 3 months. Transitional pain medicine is the medical field that focuses on understanding the mechanisms of CPSP and defining risk factors and developing preventive treatments. Unfortunately, one significant challenge is the risk of developing opioid use dependence. Multiple risk factors have been discovered, with the most common, and modifiable, being uncontrolled acute postoperative pain; preoperative anxiety and depression; and preoperative site pain, chronic pain, and opioid use.

A prospective study of chronic postsurgical pain in elderly patients: incidence, characteristics and risk factors

BACKGROUND

Due to the continued growth of surgical procedures in older adults and the significant impact of chronic postsurgical pain (CPSP), it is crucial to improve our understanding of the occurrence of CPSP as well as the appropriate prevention and treatment. We therefore conducted this study to determine the incidence, characteristics and risk factors of CPSP in elderly patients at both 3 and 6 months after surgery.

METHODS

Elderly patients (aged ≥ 60 years) undergoing elective surgery in our institution between April 2018 and March 2020 were prospectively enrolled in this study. Data on demographics, preoperative psychological well-being, intraoperative surgical and anesthesia management, and acute postoperative pain intensity were collected. At 3 and 6 months after surgery, patients received telephone interview and completed the questionnaires regarding chronic pain characteristics, analgesic consumption, and interference of the pain with activities of daily living (ADL).

RESULTS

A total of 1065 elderly patients were followed up for 6 postoperative months and included in final analysis. At 3 and 6 months after operation, the incidence of CPSP was 35.6% [95% confidence interval (95% CI) 32.7 - 38.8%] and 21.5% (95% CI 19.0% - 23.9%), respectively. CPSP cause negative impacts on patient's ADL and most particularly on mood. Neuropathic features were found in 45.1% of the patients with CPSP at 3 months. At 6 months, 31.0% of those with CPSP reported that the pain had neuropathic features. Preoperative anxiety [3 months: Odds ratio (OR) 2.244, 95% CI 1.693 to 2.973; 6 months: OR 2.397, 95% CI 1.745 to 3.294], preoperative depression (3 months: OR 1.709, 95% CI 1.292 to 2.261; 6 months: OR 1.565, 95% CI 1.136-2.156), orthopedic surgery (3 months: OR 1.927, 95% CI 1.112 to 3.341; 6 months: OR 2.484, 95% CI 1.220 to 5.061), higher pain severity on movement within postoperative 24 h (3 months: OR 1.317, 95% CI 1.191 to 1.457; 6 months: OR 1.317, 95% CI 1.177 to 1.475) were associated with a higher risk for CPSP independently at both 3 and 6 months after surgery.

CONCLUSIONS

CPSP is a common postoperative complication in elderly surgical patients. Preoperative anxiety and depression, orthopedic surgery, and greater intensity of acute postoperative pain on movement are associated with an increased risk for CPSP. It should be kept in mind that developing psychological interventions to reduce anxiety and depression and optimizing the management of acute postoperative pain will be effective in reducing the development of CPSP in this population.

The Peripheral Nerve Surgeon's Role in the Management of Neuropathic Pain

Neuropathic pain (NP) underlies significant morbidity and disability worldwide. Although pharmacologic and functional therapies attempt to address this issue, they remain incompletely effective for many patients. Peripheral nerve surgeons have a range of techniques for intervening on NP. The aim of this review is to enable practitioners to identify patients with NP who might benefit from surgical intervention. The workup for NP includes patient history and specific physical examination maneuvers, as well as imaging and diagnostic nerve blocks. Once diagnosed, there is a range of options surgeons can utilize based on specific causes of NP. These techniques include nerve decompression, nerve reconstruction, nerve ablative techniques, and implantable nerve-modulating devices. In addition, there is an emerging role for preoperative involvement of peripheral nerve surgeons for cases known to carry a high risk of inducing postoperative NP. Lastly, we describe the ongoing work that will enable surgeons to expand their armamentarium to better serve patients with NP.

Review of cooled radiofrequency ablation utilization for the treatment of symptomatic advanced knee arthritis and total knee arthroplasty

Degenerative knee osteoarthritis is a progressive debilitating condition that affects millions of people worldwide. Most patients experience limited range of motion, inflammation, swelling, and pain. Management options can lead to short- and long-term pain relief. Short-term pain relief usually involves conservative medical treatments such as NSAIDs, weight loss, physical therapy, and corticosteroid injections. The ultimate long-term pain relief treatment method involves total knee arthroplasty. The treatment algorithm for knee OA also includes managing pain until a patient is eligible for arthroplasty. Furthermore, about 20% of patients experience chronic pain after TKA without complications such as hardware loosening and infection with limited treatment options. The pathophysiology of this is unknown. Cooled radiofrequency ablation has been demonstrated to be clinically effective by disrupting the integrity of deep sensory nerves and hence interfering with transmission of pain signal. The analgesic effect after c-RFA has been reported up to 24 months. Here, we present an overview of the clinical application of cooled radiofrequency ablation and a summary of its effectiveness in the treatment of pain in the setting of advanced OA and symptomatic TKA.

Prognostic factors for chronic post-surgical pain after lung and pleural surgery: a systematic review with meta-analysis, meta-regression and trial sequential analysis

Chronic post-surgical pain is known to be a common complication of thoracic surgery and has been associated with a lower quality of life, increased healthcare utilisation, substantial direct and indirect costs, and increased long-term use of opioids. This systematic review with meta-analysis aimed to identify and summarise the evidence of all prognostic factors for chronic post-surgical pain after lung and pleural surgery. Electronic databases were searched for retrospective and prospective observational studies as well as randomised controlled trials that included patients undergoing lung or pleural surgery and reported on prognostic factors for chronic post-surgical pain. We included 56 studies resulting in 45 identified prognostic factors, of which 16 were pooled with a meta-analysis. Prognostic factors that increased chronic post-surgical pain risk were as follows: higher postoperative pain intensity (day 1, 0-10 score), mean difference (95%CI) 1.29 (0.62-1.95), p < 0.001; pre-operative pain, odds ratio (95%CI) 2.86 (1.94-4.21), p < 0.001; and longer surgery duration (in minutes), mean difference (95%CI) 12.07 (4.99-19.16), p < 0.001. Prognostic factors that decreased chronic post-surgical pain risk were as follows: intercostal nerve block, odds ratio (95%CI) 0.76 (0.61-0.95) p = 0.018 and video-assisted thoracic surgery, 0.54 (0.43-0.66) p < 0.001. Trial sequential analysis was used to adjust for type 1 and type 2 errors of statistical analysis and confirmed adequate power for these prognostic factors. In contrast to other studies, we found that age had no significant effect on chronic post-surgical pain and there was not enough evidence to conclude on sex. Meta-regression did not reveal significant effects of any of the study covariates on the prognostic factors with a significant effect on chronic post-surgical pain. Expressed as grading of recommendations, assessment, development and evaluations criteria, the certainty of evidence was high for pre-operative pain and video-assisted thoracic surgery, moderate for intercostal nerve block and surgery duration and low for postoperative pain intensity. We thus identified actionable factors which can be addressed to attempt to reduce the risk of chronic post-surgical pain after lung surgery.

Targeting the chemokine ligand 2-chemokine receptor 2 axis provides the possibility of immunotherapy in chronic pain

Chronic pain affects patients' physical and psychological health and quality of life, entailing a tremendous public health challenge. Currently, drugs for chronic pain are usually associated with a large number of side effects and poor efficacy. Chemokines in the neuroimmune interface combine with their receptors to regulate inflammation or mediate neuroinflammation in the peripheral and central nervous system. Targeting chemokines and their receptor-mediated neuroinflammation is an effective means to treat chronic pain. In recent years, growing evidence has shown that the expression of chemokine ligand 2 (CCL2) and its main chemokine receptor 2 (CCR2) is involved in its occurrence, development and maintenance of chronic pain. This paper summarises the relationship between the chemokine system, CCL2/CCR2 axis, and chronic pain, and the CCL2/CCR2 axis changes under different chronic pain conditions. Targeting chemokine CCL2 and its chemokine receptor CCR2 through siRNA, blocking antibodies, or small molecule antagonists may provide new therapeutic possibilities for managing chronic pain.

Activation of neuronal FLT3 promotes exaggerated sensorial and emotional pain-related behaviors facilitating the transition from acute to chronic pain

Acute pain has been associated with persistent pain sensitization of nociceptive pathways increasing the risk of transition from acute to chronic pain. We demonstrated the critical role of the FLT3- tyrosine kinase receptor, expressed in sensory neurons, in pain chronification after peripheral nerve injury. However, it is unclear whether injury-induced pain sensitization can also promote long-term mood disorders. Here, we evaluated the emotional and sensorial components of pain after a single (SI) or double paw incision (DI) and the implication of FLT3. DI mice showed an anxiodepressive-like phenotype associated with extended mechanical pain hypersensitivity and spontaneous pain when compared to SI mice. Behavioral exaggeration was associated with peripheral and spinal changes including increased microglia activation after DI versus SI. Intrathecal microglial inhibitors not only eliminated the exaggerated pain hypersensitivity produced by DI but also prevented anxiodepressive-related behaviors. Behavioral and cellular changes produced by DI were blocked in Flt3 knock-out animals and recapitulated by repeated intrathecal FL injections in naive animals. Finally, humanized antibodies against FLT3 reduced DI-induced behavioral and microglia changes. Altogether our results show that the repetition of peripheral lesions facilitate not only exaggerated nociceptive behaviors but also induced anxiodepressive disorders supported by spinal central changes that can be blocked by targeting peripheral FLT3.

Dorsal root ganglion stimulation for the treatment of joint pain with predominantly nociceptive characteristics: A case series

INTRODUCTION

Dorsal root ganglion stimulation (DRG-S) has recently emerged as a novel therapy in neuromodulation that demonstrated a higher rate of success than spinal cord stimulation (SCS) in a prospective, head-to-head randomized comparative trial to treat complex regional pain syndrome (CRPS) and causalgia. In contrast to SCS, DRG-S also shows promise in treating conditions that are not purely neuropathic such as axial low back pain, which has a prominent nociplastic pain component. It is not known to what extent the effectiveness of DRG-S for such indications is due to effective treatment of the neuropathic pain component versus the effects of DRG-S on mechanical pain. Although rarely studied, reporting outcomes of DRG-S to treat predominantly mechanical/nociceptive pain may help point toward expanding the utility of this therapy. Here, we present five cases of refractory mechanical pain treated with DRG-S.

METHODS

A retrospective analysis of all patients who underwent a successful DRG-S trial and implant between September 2017 and September 2021 at our institute was performed. Patients who had intractable joint pain without strong evidence of neuropathic pain were included in this case series. The Budapest criteria for CRPS, the Douleur Neuropathique 4 Questions (DN4) survey, or a definable nerve injury were used to determine the presence of neuropathic pain. Baseline assessments for pain (Numeric Rating Scale [NRS]), function (Oswestry Disability Index [ODI]), quality of life (EuroQol-5 Dimension [EQ-5D]), and other applicable joint surveys were extracted from pre-trial baseline and follow-up appointments.

RESULTS

Five patients were identified and included. Patient diagnoses consisted of refractory joint pain of the hip, knee, or ankle. Mean NRS pain scores improved by 74% from 9.2 at baseline to 2.4 at the last follow-up (mean = 28 months post-implant). From baseline to the last follow-up, mean ODI scores improved by 65% from 66 to 23 and EQ-5D scores more than doubled from an average of 0.371 to 0.797.

CONCLUSION

This clinical report illustrates the potential utility DRG-S has in treating pain that clinically presents as predominantly refractory mechanical joint pain without a significant neuropathic component. The physiological reasons for our observations may be that DRG-S is able to directly influence the conduction of nociceptive signaling at the DRG and within the spinal cord. Further investigations are warranted to determine if DRG-S is a potential treatment option for chronic mechanical pain.

Prevalence and Predictors of Chronic Postsurgical Pain After Video-Assisted Thoracoscopic Surgery: A Systematic Review and Meta-analysis

INTRODUCTION

Determining the prevalence of chronic postsurgical pain (CPSP) after video-assisted thoracoscopic surgery (VATS) and identifying CPSP predictors should improve the prognosis of patients undergoing VATS. Although several studies have investigated predictors of CPSP after VATS, there were significant dissimilarities in the findings due to the confounding of predictors.

METHODS

PubMed, Cochrane, MEDLINE, Web of Science, Chinese Biomedical Literature, and China National Knowledge Infrastructure databases were comprehensively searched using the Medical Subject Headings terms "pain, postoperative," "thoracic surgery, video-assisted," and all related free terms from inception until March 27, 2022. The Stata metaprop package was used to comprehensively analyze the incidence of CPSP following VATS. Furthermore, the pooled odds ratios (OR) or the standardized mean differences (SMD) and their corresponding 95% confidence intervals (95% CI) were calculated, and qualitative analyses were performed for predictors that could not be assessed quantitatively to evaluate the effects of the included risk factors on the occurrence of CPSP. Unadjusted odds ratios were utilized to consider the impact of non-significant estimates if the original study did not report them.

RESULTS

Of the 4302 studies, 183 were considered eligible, and 17 were finally included in this study. The overall incidence of CPSP after VATS was 35.3% (95% CI 27.1-43.5%). The qualitative synthesis results revealed that female sex, age, and acute postoperative pain were definite predictors of CPSP after VATS. The number of ports, operation time, duration of drainage, and insufficient analgesia were also considered predictors. Consistent, quantitative synthesis results also showed that the aforementioned predictors were closely related to the occurrence of CPSP after VATS. Only by quantitative analysis, postoperative chemotherapy and an educational level less than junior school were also risk factors for CPSP. Other predictors displayed no evidence or unclear evidence of association with CPSP after VATS.

CONCLUSION

This study preliminarily determined the incidence of CPSP after VATS based on the existing literature. Female sex, age, and acute pain were identified as risk factors for CPSP after VATS, and other potential risk factors were also identified and analyzed. However, as a result of the inclusion of retrospective studies and inevitable limitations in this systematic review and meta-analysis, the results of this study still need to be verified by large-scale prospective clinical studies.

TRIAL REGISTRATION

CRD42022323179.

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.

Neuropathy and pain after breast cancer treatment: a prospective observational study

OBJECTIVES

Neurological complications including pain are common after treatment for breast cancer. This prospective study investigated the symptoms, intensity and interference of chemotherapy-induced peripheral neuro-pathy. (CIPN) in the feet and hands compared to surgery- and radiation-induced neuropathy in the breast and upper arm.

METHODS

Consecutive patients referred to surgery for breast cancer were included in a prospective study and completed a questionnaire at baseline and a follow-up questionnaire and interview after one year. CIPN was assessed with the CIPN20 questionnaire and the Michigan Neuropathy Screening Instrument questionnaire (MNSIq). Pain intensity was rated on a numeric rating scale (NRS, 0-10).

RESULTS

In total 144 patients were included, of which 73 received chemotherapy. At one-year follow-up, symptoms of polyneuropathy were more common in patients treated with chemotherapy. Tingling or numbness in the feet in those treated/not treated with chemotherapy was reported by 44 (62%) and 15 (21%), respectively. Pain was present in 22 (30%) and 10 (14%), respectively. Pain in the area of surgery was reported by 66 (46%). Although less common, pain in the feet in those treated with chemotherapy was rated as more intense and with more daily life interference than pain in the surgical area (NRS 5.5 (SD 1.9) vs. 3.1 (SD 1.9).

CONCLUSIONS

Neurological complications including pain following surgery and chemotherapy represent a burden to breast cancer survivors. In those who had received chemotherapy, pain in the feet was less common than pain in the surgical area, but pain in the feet was more intense and had a higher interference with daily life. Our study emphasizes the need for either baseline data or a control population for improved estimation of the presence and severity of CIPN and pain from questionnaires.

Potential novel therapeutic strategies for neuropathic pain

Purpose

To explore the potential therapeutic strategies of different types of neuropathic pain (NP) and to summarize the cutting-edge novel approaches for NP treatment based on the clinical trials registered on ClinicalTrials.gov.

Methods

The relevant clinical trials were searched using ClinicalTrials.gov Dec 08, 2022. NP is defined as a painful condition caused by neurological lesions or diseases. All data were obtained and reviewed by the investigators to confirm whether they were related to the current topic.

Results

A total of 914 trials were included in this study. They were divided into painful diabetic neuropathy (PDN), postherpetic neuralgia (PHN), sciatica (SC), peripheral nerve injury-related NP (PNI), trigeminal neuralgia (TN), chemotherapy-induced NP (CINP), general peripheral NP (GPNP) and spinal cord injury NP (SCI-NP). Potential novel therapeutic strategies, such as novel drug targets and physical means, were discussed for each type of NP.

Conclusion

NP treatment is mainly dominated by drug therapy, and physical means have become increasingly popular. It is worth noting that novel drug targets, new implications of conventional medicine, and novel physical means can serve as promising strategies for the treatment of NP. However, more attention needs to be paid to the challenges of translating research findings into clinical practice.

Botulinum Toxin-A for the Treatment of Neuropathic Pain after Decompressive Craniotomy in Stroke: Two Cases

Botulinum toxin-A (BoNT-A) is recommended as third-line off-label treatment for the management of neuropathic pain. BoNT-A has been reported as treatment for different neuropathic pain conditions; however, not for neuropathic pain after decompressive craniotomy for stroke. The aim of this retrospective case series is to provide information on safety, the effect, and the application method of BoNT-A in clinical practice for the treatment of neuropathic pain after trepanation. This case series describes 2 patients treated in 2021 at a BoNT outpatient clinic for chronic neuropathic pain at the incisional site after decompressive craniotomy for stroke who were resistant to pain medication. Cases were a 48-year-old woman and a 63-year-old man suffering from chronic neuropathic pain since 3 and 6 years, respectively. They were treated regularly with BoNT-A with a total dose of 100 mouse units of incobotulinumtoxin-A injected into peri-incisional sites of the scalp. Both patients reported subjective decrease in pain frequency (40% and 60%), in pain intensity (60% and 90%), and an increase of quality of life (80%). BoNT-A should be further investigated as treatment for neuropathic pain - especially in underreported conditions such as neuropathic pain after craniotomy in stroke.

Spinal Cord Stimulator Therapy as a Last Resort Option in Refractory Neuropathic Groin Pain: A Case Report

A spinal cord stimulator (SCS) is an excellent therapeutic strategy for many refractory chronic pain cases. They have a multi-faceted effect in providing relief in such indicated cases that include complex regional pain syndrome (CRPS) or failed back surgery syndrome (FBSS). However, if a patient has chronic intractable neuropathic pain outside the standard indications for SCS, can a case be made for trialing SCS as a last resort option? We describe a case where a patient with neuropathic groin pain, refractory to numerous types of procedures and non-interventional modalities, successfully underwent SCS therapy as a last resort option.

Rethinking the definition of chronic postsurgical pain: composites of patient-reported pain-related outcomes vs pain intensities alone

ABSTRACT

Chronic postsurgical pain (CPSP) is defined by pain intensity and pain-related functional interference. This study included measures of function in a composite score of patient-reported outcomes (PROs) to investigate the incidence of CPSP. Registry data were analyzed for PROs 1 day and 12 months postoperatively. Based on pain intensity and pain-related interference with function, patients were allocated to the groups " CPSPF " (at least moderate pain with interference), " mixed " (milder symptoms), and " no CPSPF ". The incidence of CPSPF was compared with CPSP rates referring to published data. Variables associated with the PRO-12 score (composite PROs at 12 months; numeric rating scale 0-10) were analyzed by linear regression analysis. Of 2319 patients, 8.6%, 32.5%, and 58.9% were allocated to the groups CPSPF , mixed , and no CPSPF , respectively. Exclusion of patients whose pain scores did not increase compared with the preoperative status, resulted in a 3.3% incidence. Of the patients without pre-existing pain, 4.1% had CPSPF. Previously published pain cutoffs of numeric rating scale >0, ≥3, or ≥4, used to define CPSP, produced rates of 37.5%, 9.7%, and 5.7%. Pre-existing chronic pain, preoperative opioid medication, and type of surgery were associated with the PRO-12 score (all P < 0.05). Opioid doses and PROs 24 hours postoperatively improved the fit of the regression model. A more comprehensive assessment of pain and interference resulted in lower CPSP rates than previously reported. Although inclusion of CPSP in the ICD-11 is a welcome step, evaluation of pain characteristics would be helpful in differentiation between CPSPF and continuation of pre-existing chronic pain.

Intensity-adjustable pain management with prolonged duration based on phase-transitional nanoparticles-assisted ultrasound imaging-guided nerve blockade

Background

The lack of a satisfactory strategy for postoperative pain management significantly impairs the quality of life for many patients. However, existing nanoplatforms cannot provide a longer duration of nerve blockage with intensity-adjustable characteristics under imaging guidance for clinical applications.

Results

To overcome this challenge, we proposed a biocompatible nanoplatform that enables high-definition ultrasound imaging-guided, intensity-adjustable, and long-lasting analgesia in a postoperative pain management model in awake mice. The nanoplatform was constructed by incorporating perfluoropentane and levobupivacaine with red blood cell membranes decorated liposomes. The fabricated nanoplatform can achieve gas-producing and can finely escape from immune surveillance in vivo to maximize the anesthetic effect. The analgesia effect was assessed from both motor reactions and pain-related histological markers. The findings demonstrated that the duration of intensity-adjustable analgesia in our platform is more than 20 times longer than free levobupivacaine injection with pain relief for around 3 days straight. Moreover, the pain relief was strengthened by repeatable ultrasound irradiation to effectively manage postoperative pain in an intensity-adjustable manner. No apparent systemic and local tissue injury was detected under different treatments.

Conclusion

Our results suggest that nanoplatform can provide an effective strategy for ultrasound imaging-guided intensity-adjustable pain management with prolonged analgesia duration and show considerable transformation prospects.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01707-z.