The IASP classification of chronic pain for ICD-11: chronic neuropathic pain

Principles of Pain Management

OBJECTIVE

This article introduces the general principles of assessing, diagnosing, and managing pain relevant to neurologic practice.

LATEST DEVELOPMENTS

Scientific understanding of and clinical practices related to pain and pain management are advancing. The field is remarkable for the diversity of health professions engaged in this effort, including physicians, scientists, psychologists, pharmacists, and many others. Pain classification is transforming with pending changes to the International Classification of Diseases diagnostic coding system, and pain assessment has moved toward consistent application of the biopsychosocial model. The diagnosis of pain has continued to become more sophisticated with the development of additional testing modalities, clearer classification systems, and diagnostic criteria. Pain management requires both pharmacologic and nonpharmacologic elements; systematic review evidence for both of these and interventional and surgical management are increasingly available. The context of treatment remains important given the impact of social determinants of health and limitations of access to diagnostic and treatment resources. Due to global and interprofessional collaborations as well as new research funding, the outlook is positive.

ESSENTIAL POINTS

Pain is a protean experience for humans; functional MRI (fMRI) and other research modalities show that pain perception is highly multifocal, and modulation occurs at many nervous system levels. Neurologists bring special skills to pain evaluation and management, are well equipped to appreciate both the focal and diffuse nature of pain, and can envision how pain attenuates sleep, cognitive function, mobility, motivation, and social connection. By operationalizing expert knowledge of the nervous system, implementing relevant therapies, and collaborating with diverse health professions to manage pain, neurologists can succeed at and find meaning in optimizing patient outcomes.

Clinicians diagnosing virtual patients with the classification algorithm for chronic pain in the ICD-11 (CAL-CP) achieve better diagnoses and prefer the algorithm to standard tools: An experimental validation study

BACKGROUND

The ICD-11 classification of chronic pain comprises seven categories, each further subdivided. In total, it contains over 100 diagnoses each based on 5-7 criteria. To increase diagnostic reliability, the Classification Algorithm for Chronic Pain in the ICD-11 (CAL-CP) was developed. The current study aimed to evaluate the CAL-CP regarding the correctness of assigned diagnoses, utility and ease of use.

METHODS

In an international online study, n = 195 clinicians each diagnosed 4 out of 8 fictitious patients. The clinicians interacted via chat with the virtual patients to collect information and view medical histories and examination findings. The patient cases differed in complexity: simple patients had one chronic pain diagnosis; complex cases had two. In a 2 × 2 repeated-measures design with the factors tool (algorithm/standard browser) and diagnostic complexity (simple/complex), clinicians used either the algorithm or the ICD-11 browser for their diagnoses. After each case, clinicians indicated the pain diagnoses and rated the diagnostic process. The correctness of the assigned diagnoses and the ratings of the algorithm's utility and ease of use were analysed.

RESULTS

The use of the algorithm resulted in more correct diagnoses. This was true for chronic primary and secondary pain diagnoses. The clinicians preferred the algorithm over the ICD-11 browser, rating it easier to work with and more useful. Especially novice users benefited from the algorithm.

CONCLUSIONS

The use of the algorithm increases the correctness of the diagnoses for chronic pain and is well accepted by clinicians. The CAL-CP's use should be considered in routine care and research contexts.

SIGNIFICANCE STATEMENT

The ICD-11 has come into effect in January 2022. Clinicians and researchers will soon begin using the new classification of chronic pain. To facilitate clinicians training and diagnostic accuracy, a classification algorithm was developed. The paper investigates whether clinicians using the algorithm-as opposed to the generic tools provided by the WHO-reach more correct diagnoses when they diagnose standardized patients and how they rate the comparative utility of the diagnostic instruments available.

Black-white hole pattern: an investigation on the automated chronic neuropathic pain detection using EEG signals

Electroencephalography (EEG) signals provide information about the brain activities, this study bridges neuroscience and machine learning by introducing an astronomy-inspired feature extraction model. In this work, we developed a novel feature extraction function, black-white hole pattern (BWHPat) which dynamically selects the most suitable pattern from 14 options. We developed BWHPat in a four-phase feature engineering model, involving multileveled feature extraction, feature selection, classification, and cortex map generation. Textural and statistical features are extracted in the first phase, while tunable q-factor wavelet transform (TQWT) aids in multileveled feature extraction. The second phase employs iterative neighborhood component analysis (INCA) for feature selection, and the k-nearest neighbors (kNN) classifier is applied for classification, yielding channel-specific results. A new cortex map generation model highlights the most active channels using median and intersection functions. Our BWHPat-driven model consistently achieved over 99% classification accuracy across three scenarios using the publicly available EEG pain dataset. Furthermore, a semantic cortex map precisely identifies pain-affected brain regions. This study signifies the contribution to EEG signal classification and neuroscience. The BWHPat pattern establishes a unique link between astronomy and feature extraction, enhancing the understanding of brain activities.

Effectiveness of Digital Health Interventions (DHI) in Chronic Pain Management: A Scoping Review of Current Evidence and Emerging Trends

This review aims to address the impact of digital health interventions (DHIs) on chronic pain management, specifically, mHealth, eHealth, wearable devices, virtual reality (VR), and artificial intelligence. The following study identifies and assesses DHIs' efficacy in specific chronic pain conditions and then extrapolates improved outcomes and patient groups that benefit from their use. Using a systematic methodology, this review synthesizes findings that could improve knowledge for patients and practitioners in chronic pain management while also addressing gaps in understanding the impact of DHIs. Sub-questions guide the identification of gaps and recommendations assessing DHIs' effectiveness for pain reduction and improved quality of life. A systematic search across databases (EMBASE, Ovid MEDLINE, CINAHL, Web of Sciences, Cochrane Central) targets original, English-language, peer-reviewed studies (2013-2023). The inclusion criteria cover DHIs in chronic pain management for adults age 18+, excluding non-full texts, reviews, opinion pieces, or unrelated articles. Search terms include "chronic pain management" OR "long-term pain relief strategies" OR "sustained pain alleviation" OR "pain control for chronic conditions" OR "chronic pain" AND "ehealth interventions" OR "mobile health interventions" OR "digital therapy" OR "health informatic solutions" OR "digital health intervention." After applying inclusion criteria, 34 articles from 11 countries are included, with studies conducted primarily in the United States (n = 17), United Kingdom (n = 4), and Australia (n = 3). DHIs are emerging as effective tools in pain management, as they can emphasize patient autonomy and communication with clinicians while enabling medical self-management in diverse populations. These various digital interventions show promise in reducing pharmaceutical usage and deferring surgical procedures, with most studies reporting positive outcomes in pain reduction. DHIs were also associated with positive mental health outcomes; however, some studies found no significant improvement. Additionally, interventions targeting pain catastrophizing showed varied results, with some app-based approaches demonstrating promise. Overall, the review underscores the potential of DHIs in improving chronic pain management outcomes.

A combined treatment for self-traumatic chronic skin lesions associated with post-surgical neuropathic pain in a domestic cat: a pharmacological and cold atmospheric plasma approach

Cold atmospheric plasma (CAP) has been employed as a therapy against both acute and chronic skin lesions, contaminated or not, and has effects on angiogenesis and reepithelialization promoting healing. In this context, the present study aimed to evaluate the effects of a CAP jet associated with pharmacological treatment described by the 2015 AAHA/AAFP pain management guidelines and the 2022 WSAVA guidelines for the recognition, assessment, and treatment of pain, on the healing of chronic skin lesions caused by a pruritic reaction resulting from post-surgical neuropathic pain. To this end, a single CAP application was performed on a feline patient with a 6 months old recurrent contaminated cervical skin lesions along with administration of ketamine (10 µg/kg/min) following the prescription of prednisone (1 mg/kg, SID, 6 days), gabapentin (8 mg/kg, BID, 60 days) and amitriptyline (0.5 mg /kg, SID, 60 days). A single application of plasma associated with an NMDA antagonist, anti-inflammatory steroid, tricyclic antidepressant and gabapentinoid thus provided a significant improvement in the macroscopic appearance of the lesion within 10 days, and the owner reported the cessation of intense itching within the first four hours after treatment and a consequent improvement in the animal's quality of life. The medical treatment was finished almost a year since the writing of this paper, without clinical or reported recurrent signs of the condition. Therefore, we observed that single dose CAP application associated with ketamine, gabapentin, amitriptyline and prednisone leads to significant healing of chronically infected skin lesions resulting from post-surgical neuropathic pain.

Attentional biases towards emotional information in chronic pain: A multilevel meta-analysis of eye-tracking studies

OBJECTIVE

This meta-analysis reviewed the existing literature on attentional biases towards emotional stimuli measured with eye-tracking methodologies in individuals with chronic pain.

METHOD

Eighteen relevant studies (n = 1331 participants) were identified through three electronic databases: PubMed, PsycInfo, and Scopus. A multilevel random-effects meta-analysis was conducted by using the standardized mean difference between gaze variables for emotional and neutral stimuli with Hedge's correction as the effect size (ES).

RESULTS

Between-group analyses revealed that healthy individuals make longer first fixation towards neutral stimuli compared to chronic pain patients. Within-group analyses showed that, compared to the healthy control group, the chronic pain group had more first fixations towards pain-related stimuli than to neutral ones and had shorter fixation duration towards anger-related stimuli than to neutral stimuli. A moderation effect of paradigm and type of stimuli was also found.

CONCLUSIONS

This is the first meta-analysis exploring attentional biases not only towards pain-related stimuli, but also towards other emotional information. Our findings revealed that chronic pain individuals tend to focus their attention firstly on pain-related information in comparison to healthy individuals. Furthermore, chronic pain individuals maintain their attention on anger-related stimuli less than on neutral ones.

Chronic Pain and Obesity in Community-Dwelling Adults: Findings from the National Health and Nutrition Examination Survey

Background

Chronic pain and obesity, together with their corresponding characteristics, are concerning health issues with high socioeconomic burden. The objective of this study is to ascertain the prevalence of chronic pain among individuals residing in the community and examine its association with obesity.

Methods

The present study employed a cross-sectional design and analyzed data from three cycles of the National Health and Nutrition Examination Survey (NHANES). Univariate and multivariate logistic regression analysis were performed to examine the relationship between chronic pain and obesity. To evaluate the potential nonlinear association of chronic with body mass index (BMI), the restricted cubic spline (RCS) analysis was performed in multivariable-adjusted models. The researchers conducted subgroup analyses in order to investigate the potential influence of different confounding factors on the relationship between chronic pain and obesity.

Results

Our final analysis included a sample size of 13,700 participants with higher prevalence of chronic pain with higher BMI, older age, female sex, lower educational level, smoking, and other pathologies. The prevalence of chronic pain in different BMI groups was 17.0% (underweight), 11.8% (normal weight), 12.9% (overweight), and 17.9% (obesity), respectively. In the fully adjusted model, obesity was associated with a 45% increase in the risk of chronic pain compared with the normal weight. The RCS analyses revealed a nonlinear and J-shaped positive association between BMI and chronic pain (OR 1.45, 95% CI 1.27-1.66, all P for nonlinearity < 0.05). The results of the subgroup analyses indicate that the presence of osteoporosis significantly influenced the relationship between obesity and chronic pain, as evidenced by a statistically significant interaction effect (OR 2.25, 95% CI 1.38-3.68, P for interaction = 0.019).

Conclusion

The presence of obesity was found to be significantly correlated with an increased likelihood of experiencing chronic pain among adults living in the United States.

The use of naltrexone in the treatment of chronic pain: a systematic review

This study aims to assess the efficacy of low-dose naltrexone (LDN) in treating chronic pain. We conducted a systematic review using the PICO strategy: (P) Patients with chronic pain, (I) Use of oral naltrexone, (C) Placebo or active drug and (O) Pain relief and quality of life. We included articles from PubMed, Scopus, Cochrane CENTRAL and EMBASE databases. Seven randomized clinical trials involving 406 patients were analyzed. The doses ranging from 2 to 4.5 mg once daily across all studies. Various chronic pain conditions were evaluated. The results suggest that low-dose naltrexone is not effective in managing chronic pain and improving the quality of life in patients with diverse chronic pain conditions. However, further research with larger sample sizes and standardized methodologies is necessary.

A comprehensive review of traditional Chinese medicine in treating neuropathic pain

Neuropathic pain (NP) is a common, intractable chronic pain caused by nerve dysfunction and primary lesion of the nervous system. The etiology and pathogenesis of NP have not yet been clarified, so there is a lack of precise and effective clinical treatments. In recent years, traditional Chinese medicine (TCM) has shown increasing advantages in alleviating NP. Our review aimed to define the therapeutic effect of TCM (including TCM prescriptions, TCM extracts and natural products from TCM) on NP and reveal the underlying mechanisms. Literature from 2018 to 2024 was collected from databases including Web of Science, PubMed, ScienceDirect, Google academic and CNKI databases. Herbal medicine, Traditional Chinese medicines (TCM), neuropathic pain, neuralgia and peripheral neuropathy were used as the search terms. The anti-NP activity of TCM is clarified to propose strategies for discovering active compounds against NP, and provide reference to screen anti-NP drugs from TCM. We concluded that TCM has the characteristics of multi-level, multi-component, multi-target and multi-pathway, which can alleviate NP through various pathways such as anti-inflammation, anti-oxidant, anti-apoptotic pathway, regulating autophagy, regulating intestinal flora, and influencing ion channels. Based on the experimental study and anti-NP mechanism of TCM, this paper can offer analytical evidence to support the effectiveness in treating NP. These references will be helpful to the research and development of innovative TCM with multiple levels and multiple targets. TCM can be an effective treatment for NP and can serve as a treasure house for new drug development.

TLR4 induced TRPM2 mediated neuropathic pain

Ion channels play an important role in mediating pain through signal transduction, regulation, and control of responses, particularly in neuropathic pain. Transient receptor potential channel superfamily plays an important role in cation permeability and cellular signaling. Transient receptor potential channel Melastatin 2 (TRPM2) subfamily regulates Ca2+ concentration in response to various chemicals and signals from the surrounding environment. TRPM2 has a role in several physiological functions such as cellular osmosis, temperature sensing, cellular proliferation, as well as the manifestation of many disease processes such as pain process, cancer, apoptosis, endothelial dysfunction, angiogenesis, renal and lung fibrosis, and cerebral ischemic stroke. Toll-like Receptor 4 (TLR4) is a critical initiator of the immune response to inflammatory stimuli, particularly those triggered by Lipopolysaccharide (LPS). It activates downstream pathways leading to the production of oxidative molecules and inflammatory cytokines, which are modulated by basal and store-operated calcium ion signaling. The cytokine production and release cause an imbalance of antioxidant enzymes and redox potential in the Endoplasmic Reticulum and mitochondria due to oxidative stress, which results from TLR-4 activation and consequently induces the production of inflammatory cytokines in neuronal cells, exacerbating the pain process. Very few studies have reported the role of TRPM2 and its association with Toll-like receptors in the context of neuropathic pain. However, the molecular mechanism underlying the interaction between TRPM2 and TLR-4 and the quantum of impact in acute and chronic neuropathic pain remains unclear. Understanding the link between TLR-4 and TRPM2 will provide more insights into pain regulation mechanisms for the development of new therapeutic molecules to address neuropathic pain.

The dual role of TRPV1 in peripheral neuropathic pain: pain switches caused by its sensitization or desensitization

The transient receptor potential vanilloid 1 (TRPV1) channel plays a dual role in peripheral neuropathic pain (NeuP) by acting as a "pain switch" through its sensitization and desensitization. Hyperalgesia, commonly resulting from tissue injury or inflammation, involves the sensitization of TRPV1 channels, which modulates sensory transmission from primary afferent nociceptors to spinal dorsal horn neurons. In chemotherapy-induced peripheral neuropathy (CIPN), TRPV1 is implicated in neuropathic pain mechanisms due to its interaction with ion channels, neurotransmitter signaling, and oxidative stress. Sensitization of TRPV1 in dorsal root ganglion neurons contributes to CIPN development, and inhibition of TRPV1 channels can reduce chemotherapy-induced mechanical hypersensitivity. In diabetic peripheral neuropathy (DPN), TRPV1 is involved in pain modulation through pathways including reactive oxygen species and cytokine production. TRPV1's interaction with TRPA1 channels further influences chronic pain onset and progression. Therapeutically, capsaicin, a TRPV1 agonist, can induce analgesia through receptor desensitization, while TRPV1 antagonists and siRNA targeting TRPV1 show promise in preclinical studies. Cannabinoid modulation of TRPV1 provides another potential pathway for alleviating neuropathic pain. This review summarizes recent preclinical research on TRPV1 in association with peripheral NeuP.

Topical treatment of chemotherapy-induced peripheral neuropathy (CIPN) with high-concentration (179 mg) capsaicin patch in breast cancer patients - results of the QUCIP study

Background

Chemotherapy-induced peripheral neuropathy (CIPN) following oral or intravenous chemotherapy often results in neuropathic pain, accompanied by symptoms such tingling, burning and hypersensitivity to stimuli, with a notable decline in quality of life (QoL). Effective therapies for CIPN are lacking, with a high demand for analgesics to address this issue. The QUCIP study aimed to assess the effectiveness of high concentration (179 mg) capsaicin patch (HCCP) in alleviating neuropathic pain and associated symptoms in breast cancer patients with confirmed CIPN.

Methods

QUCIP is a prospective, multi-center observational study spanning 36 weeks with up to three HCCP treatments. Initial treatment (visit V0) was followed by two telephone contacts (T1, T2) and subsequent face-to-face visits every 12 weeks or upon retreatment (visits V1-V3). 73 female patients with painful CIPN post neoadjuvant/adjuvant breast cancer therapy were enrolled. Primary endpoint was the reduction of neuropathic pain symptom score (painDETECT®). Secondary endpoints included improvements in CIPN-specific QoL (QLQ-CIPN20), reductions in pain intensity (numeric pain rating scale, NPRS), and achievement of ≥ 30% and ≥ 50% pain reduction.

Results

Median age was 61 years, with 52.0% of patients experiencing peripheral neuropathic pain for > 1 year (> 2 years: 34.2%). The painDETECT® score significantly decreased from baseline (19.71 ± 4.69) to 15.80 ± 6.20 after initial treatment (p < 0.0001) and continued to decrease at follow-up visits. The NPRS indicated significant pain intensity reduction at each time point, particularly pronounced in patients receiving three HCCP treatments. Clinically significant pain relief of ≥ 30% increased from 25.0% at week 4 (T2) to 36.2%, 43.5%, and 40.0% at weeks 12 (V1), 24 (V2), and 36 (V3), respectively. The percentage of patients achieving pain relief of ≥ 50% increased from 14.7% at T2 to 15.5%, 21.7% and 32.5% at V1, V2 and V3, respectively. Patients further reported a significant improvement in their CIPN-related QoL throughout the study. Adverse drug reactions (ADRs) mainly included application site reactions.

Conclusion

In this study, HCCP shows benefit in managing CIPN in real-world settings. The data demonstrate a sustained and progressive reduction in neuropathic pain and symptomatology, confirming the clinical benefit of repeated treatment observed in former clinical trials. HCCP treatment has also the potential to significantly improve the QoL associated with CIPN. The safety profile of HCCP was confirmed, supporting its use in clinical practice.

Drugs used for pain management in gastrointestinal surgery and their implications

Pain is the predominant symptom troubling patients. Pain management is one of the most important aspects in the management of surgical patients leading to early recovery from surgical procedures or in patients with chronic diseases or malignancy. Various groups of drugs are used for dealing with this; however, they have their own implications in the form of adverse effects and dependence. In this article, we review the concerns of different pain-relieving medicines used postoperatively in gastrointestinal surgery and for malignant and chronic diseases.

Chronic Pain and Bone-Related Pathologies: A Narrative Review

Purpose

Pain related to bone may occur as a result of trauma, bone fracture, genetic disease, arthritis, benign or malignant primary bone tumors and bone cancer metastases. We discuss the pathophysiology of chronic bone-related pain, treatment options and therapeutic perspectives.

Methods

Using predefined terms, we searched PubMed, MEDLINE, and Google Scholar for meta-analyses, evidence-based reviews, and clinical practice guidelines. This narrative article reviews pathologies linked to chronic bone pain and discusses the preventive and therapeutic strategies for better bone pain management.

Results

Pathophysiology of bone-related pain is complex, especially in cancer conditions and missing gaps are underlined. Treatment of pain, after adequate evaluation, includes classical analgesics, adjuvants for neuropathic and refractory pain, specific bone drugs, surgery and non-pharmacological approaches. Prevention of chronic bone pain encompasses prevention of central sensitization and of causal diseases.

Conclusion

Translational research, drug repurposing, an interdisciplinary approach and a person-centered assessment to evaluate, beyond pain, physical, social and functional abilities, are proposed future directions to improve chronic bone pain management and optimize independence and quality of life.

Summary

Chronic bone-related pain is frequent and is associated with an impairment of quality of life. In this review, we summarize the pathophysiology of chronic bone pain, describe treatment approaches and envisage new avenues for pain alleviation. Our article will help doctors manage chronic bone pain and address unmet needs for future research to alleviate bone-related pain.

Radiofrequency stimulation of the dorsal root ganglion as a diagnostic tool for radicular pain syndromes: six representative cases

BACKGROUND

We discuss the diagnostic benefit of pulsed radiofrequency (PRF) of the dorsal root ganglion (DRG) in a case series of patients with different pathologies. We expand the diagnostic potential of DRG stimulation beyond paresthesia mapping by using DRG stimulation to help determine the role of the DRG in the patient's pain and narrow down the etiology. In some cases, DRG stimulation was also part of the treatment plan.

METHODS

Six patients underwent DRG radiofrequency as a diagnostic/therapeutic step before considering implantation of a DRG neurostimulator. First, patients underwent a basic bedside neurological evaluation. Next, an electrode was placed in the epidural space through the sacral hiatus or between vertebral laminae. Then, sensory stimulation was applied at 50 Hz and gradually increased from 0.1 V until the patient reported paresthesia or until a maximum intensity of 2 V was reached. Patients were asked to describe where the stimulation was felt and outline the anatomical area the paresthesia covered. Then a motor stimulation was applied at 2 Hz until muscle twitching was reported by the patient or observed by the physician.

RESULTS

The information obtained helped diagnose the type of lesion as principally preganglionic, ganglionic, or postganglionic. This information guided patient management.

CONCLUSION

PRF of the DRG can provide valuable diagnostic information and is a useful step before ganglionic electrode implantation. In all cases, PRF of the DRG provided valuable diagnostic information and guided management options.

Multiple sclerosis: emerging epidemiological trends and redefining the clinical course

Multiple sclerosis is a chronic, inflammatory, and neurodegenerative disease of the central nervous system and a major cause of neurological disability in young adults. Its prevalence and incidence are increasing, and it has been estimated at over 2.8 million cases worldwide, in addition to recent trends towards a shift in MS prevalence to older ages, with peak prevalence estimates in the sixth decade of life. Although historically the relapsing and progressive phases of the disease have been considered separate clinical entities, recent evidence of progression independent of relapse activity (PIRA) has led to a reconsideration of multiple sclerosis as a continuum, in which relapsing and progressive features variably coexist from the earliest stages of the disease, challenging the traditional view of the disease course. In this Series article, we provide an overview of how the traditional description of the clinical course of MS and epidemiological trends in Europe have evolved. For this purpose, we focus on the concept of PIRA, discussing its potential as the main mechanism by which patients acquire disability, how its definition varies between studies, and ongoing research in this field. We emphasise the importance of incorporating the assessment of hidden clinical manifestations into patient management to help uncover and quantify the PIRA phenomenon and the possible implications for future changes in the clinical classification of the disease. At the same time, we provide insights into overcoming the challenges of identifying and defining PIRA and adopting a new understanding of the clinical course of MS.

Autonomic features of craniofacial neuralgias: a systematic review with meta-analysis

The aim of the study is to describe the severity, temporal characteristics, and types of autonomic features as they relate to the characteristics of pain of the neuralgias. Also, to describe, based on literature, how these autonomic features can affect the treatment outcomes of patients with craniofacial neuralgias. We carried out a literature search using five databases, PubMed, Embase, OVID, Scopus and Web of Science. The search was executed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The protocol for this systematic review and meta-analysis was registered on PROSPERO CRD42021235319. 40% of all patients with craniofacial neuralgias had at least one autonomic feature. Out of the craniofacial neuralgias, trigeminal neuralgia was the most reported, with lacrimation being the most prevalent concomitant autonomic feature. There was also differences in the occurrence of the autonomic features dependent on which branch of a nerve such as the trigeminal nerve, was afflicted. When trigeminal neuralgia is excluded, the rest of the craniofacial neuralgias had reported autonomic features 28% of the pain events. (95% Confidence Interval: 2-90%). Contrary to the conventional belief, we found certain autonomic features to be more predominant than others, in specific craniofacial neuralgias. The prevalence of the autonomic features for all craniofacial neuralgias in the descending order is as follows, lacrimation, conjunctival injection, nasal congestion, rhinorrhea, flushing, edema/swelling, salivation, ptosis and sweating. With trigeminal neuralgia, the most common autonomic feature was lacrimation, and the least common was nasal congestion.

Pretreatment Brain White Matter Integrity Associated With Neuropathic Pain Relief and Changes in Temporal Summation of Pain Following Ketamine

Neuropathic pain (NP) is a prevalent condition often associated with heightened pain responsiveness suggestive of central sensitization. Neuroimaging biomarkers of treatment outcomes may help develop personalized treatment strategies, but white matter (WM) properties have been underexplored for this purpose. Here we assessed whether WM pathways of the default mode network (DMN: medial prefrontal cortex [mPFC], posterior cingulate cortex, and precuneus) and descending pain modulation system (periaqueductal gray [PAG]) are associated with ketamine analgesia and attenuated temporal summation of pain (TSP, reflecting central sensitization) in NP. We used a fixel-based analysis of diffusion-weighted imaging data to evaluate WM microstructure (fiber density [FD]) and macrostructure (fiber bundle cross-section) within the DMN and mPFC-PAG pathways in 70 individuals who underwent magnetic resonance imaging and TSP testing; 35 with NP who underwent ketamine treatment and 35 age- and sex-matched pain-free individuals. Individuals with NP were assessed before and 1 month after treatment; those with ≥30% pain relief were considered responders (n = 18), or otherwise as nonresponders (n = 17). We found that WM structure within the DMN and mPFC-PAG pathways did not differentiate responders from nonresponders. However, pretreatment FD in the anterior limb of the internal capsule correlated with pain relief (r=.48). Moreover, pretreatment FD in the DMN (left mPFC-precuneus/posterior cingulate cortex; r=.52) and mPFC-PAG (r=.42) negatively correlated with changes in TSP. This suggests that WM microstructure in the DMN and mPFC-PAG pathway is associated with the degree to which ketamine reduces central sensitization. Thus, fixel metrics of WM structure may hold promise to predict ketamine NP treatment outcomes. PERSPECTIVE: We used advanced fixel-based analyses of MRI diffusion-weighted imaging data to identify pretreatment WM microstructure associated with ketamine outcomes, including analgesia and markers of attenuated central sensitization. Exploring associations between brain structure and treatment outcomes could contribute to a personalized approach to treatment for individuals with NP.

Combined antiallodynic effects of Neurotropin®-tramadol and Neurotropin®-mirogabalin in rats with L5-spinal nerve ligation

We aimed to examine the efficacy of combination therapies of Neurotropin® with tramadol and Neurotropin with mirogabalin for neuropathic pain management. A neuropathic pain model (L5 spinal nerve ligation model: L5-SNL) using male Wistar rats was generated through tight ligation of the left fifth lumbar nerve using silk sutures. Mechanical allodynia was assessed using the 50% paw withdrawal threshold. The combined antiallodynic effects were evaluated using isobolographic analyses. Small intestinal transit was evaluated using the charcoal meal test, and motor coordination using the rota-rod test. Neurotropin (50-200 NU/kg, p.o.), tramadol (7.5-60 mg/kg, p.o.), and mirogabalin (3-30 mg/kg, p.o.) showed a dose-dependent antiallodynic effect in L5-SNL rats. The combined antiallodynic effects of Neurotropin and tramadol were additive or synergistic, whereas those of Neurotropin and mirogabalin were additive. Neurotropin (100-400 NU/kg, p.o.) did not affect the small intestinal transit, whereas tramadol (30-100 mg/kg, p.o.) significantly inhibited it. Neurotropin (100-400 NU/kg, p.o.) did not affect the walking time, whereas mirogabalin (10-100 mg/kg, p.o.) significantly decreased it. Neurotropin dose-dependently ameliorated mechanical allodynia in rats, and combination therapy with Neurotropin-tramadol or Neurotropin-mirogabalin may alleviate neuropathic pain without aggravating the adverse effects of tramadol and mirogabalin.

Intraoperative nitrous oxide inhalation to prevent chronic postsurgical pain in video-assisted thoracoscopic surgery: a prospective observational cohort study

Background

Chronic postsurgical pain (CPSP) is a significant detriment to postsurgical recovery. Previous studies have shown that nitrous oxide (N2O) may produce long-term analgesia and may benefit the prevention of CPSP in Chinese patients. We tested the hypothesis that N2O is a protective factor against chronic pain after video-assisted thoracoscopic surgery (VATS).

Methods

Two groups of patients with and without N2O inhalation during VATS in Peking Union Medical College Hospital were recruited. Perioperative information was documented, and postsurgical pain was followed up by telephone. The primary outcome was the presence of CPSP at 6 months postoperatively. Odds ratios (ORs) and their 95% confidence intervals (CIs) were estimated using a multivariate logistic regression model adjusted for relevant confounding factors.

Results

A total of 833 patients were eligible, among whom 33.6% were male and 66.4% were female, with an average age of 56.3±11.1 years. A total of 387 (46.5%) patients reported incision-related pain at 6 months after surgery, and 160 (40.0%) out of 400 patients with N2O inhalation during surgery and 227 (52.4%) out of 433 patients without N2O inhalation during surgery developed CPSP. After adjusting for confounding factors, N2O inhalation during surgery was associated with lower odds of CPSP (OR =0.654; 95% CI: 0.480-0.890; P=0.007).

Conclusions

N2O inhalation during surgery was associated with lower odds of CPSP in VATS patients, and N2O may benefit the prevention of chronic pain after thoracoscopic surgery.

Cannabidiol in the dorsal hippocampus attenuates emotional and cognitive impairments related to neuropathic pain: The role of prelimbic neocortex-hippocampal connections

BACKGROUND AND PURPOSE

Chronic neuropathic pain (NP) is commonly associated with cognitive and emotional impairments. Cannabidiol (CBD) presents a broad spectrum of action with a potential analgesic effect. This work investigates the CBD effect on comorbidity between chronic NP, depression, and memory impairment.

EXPERIMENTAL APPROACH

The connection between the neocortex and the hippocampus was investigated with biotinylated dextran amine (BDA) deposits in the prelimbic cortex (PrL). Wistar rats were submitted to chronic constriction injury (CCI) of the sciatic nerve and CA1 treatment with CBD (15, 30, 60 nmol).

KEY RESULTS

BDA-labeled perikarya and terminal buttons were found in CA1 and dentate gyrus. CCI-induced mechanical and cold allodynia increased c-Fos protein expression in the PrL and CA1. The number of astrocytes in PrL and CA1 increased, and the number of neuroblasts decreased in CA1. Animals submitted to CCI procedure showed increasing depressive-like behaviors, such as memory impairment. CBD (60 nmol) treatment decreased mechanical and cold allodynia, attenuated depressive-associated behaviors, and improved memory performance. Cobalt chloride (CoCl2: 1 nM), WAY-100635 (0.37 nmol), and AM251 (100 nmol) intra-PrL reversed the effect of CA1 treatment with CBD (60 nmol) on nociceptive, cognitive, and depressive behaviors.

CONCLUSION

CBD represents a promising therapeutic perspective in the pharmacological treatment of chronic NP and associated comorbidities such as depression and memory impairments. The CBD effects possibly recruit the CA1-PrL pathway, inducing neuroplasticity. CBD acute treatment into the CA1 produces functional and molecular morphological improvements.

Common alterations in parallel metabolomic profiling of serum and spinal cord and mechanistic studies on neuropathic pain following PPARα administration

Neuropathic pain (NP) is usually treated with analgesics and symptomatic therapy with poor efficacy and numerous side effects, highlighting the urgent need for effective treatment strategies. Recent studies have reported an important role for peroxisome proliferator-activated receptor alpha (PPARα) in regulating metabolism as well as inflammatory responses. Through pain behavioral assessment, we found that activation of PPARα prevented chronic constriction injury (CCI)-induced mechanical allodynia and thermal hyperalgesia. In addition, PPARα ameliorated inflammatory cell infiltration at the injury site and decreased microglial activation, NOD-like receptor protein 3 (NLRP3) inflammasome production, and spinal dendritic spine density, as well as improved serum and spinal cord metabolic levels in mice. Administration of PPARα antagonists eliminates the analgesic effect of PPARα agonists. PPARα relieves NP by inhibiting neuroinflammation and functional synaptic plasticity as well as modulating metabolic mechanisms, suggesting that PPARα may be a potential molecular target for NP alleviation. However, the effects of PPARα on neuroinflammation and synaptic plasticity should be further explored.

BMP10 accelerated spinal astrocytic activation in neuropathic pain via ALK2/smad1/5/8 signaling

Background

Astrocytic activation in the spinal dorsal horn contributes to the central sensitization of neuropathic pain. Bone morphogenetic protein (BMP) 10, one of the BMPs highly expressed in the central nervous system, has been demonstrated to have an accelerated effect on astrocytic activation. This study aimed to investigate the functional effects of BMP10 on the activation of astrocytes in the spinal dorsal horn of animal model of neuropathic pain and to explore potential mechanisms involved in this process.

Methods

A neuropathic pain mice model was established using the spared nerve injury (SNI). Western blot analysis was performed to detect the expressional levels of BMP10, activin receptor-like receptor 2 (ALK2), Smad1/5/8, phosphorylated Smad1/5/8, and glial fibrillary acidic protein (GFAP). Immunofluorescence staining was used to detect BMP10, ALK2, and GFAP distribution and expression. The behavioral changes in mice were evaluated using paw withdrawal threshold (PWT), thermal withdrawal latency (TWL), and open field test (OFT). The BMP10 siRNA, Smad1 siRNA, BMP10 peptide, and ALK2-IN-2 (ALK2 inhibitor) were intrathecally administrated to mice. A model of lipopolysaccharide (LPS)-stimulated astrocytes was established to investigate the effect of Smad1. The transfection efficiency of siRNAs was detected by western blot and qRT-PCR analysis.

Results

BMP10 levels were increased in the L4-6 ipsilateral spinal dorsal horn of SNI mice and particularly elevated in astrocytes. Consistently, GFAP and phosphorylated Smad1/5/8 were upregulated in the L4-6 ipsilateral spinal dorsal horn after SNI, indicating the activation of astrocytes and Smad1/5/8 signaling. An intrathecal injection of BMP10 siRNA abrogated pain hypersensitivity and astrocytic activation in SNI mice. In addition, intrathecal administration of BMP10 peptide evoked pain hypersensitivity and astrocytic activation in normal mice, and this action was reversed by inhibiting the ALK2. Furthermore, targeting Smad1 in vitro with the help of siRNA inhibited the activation of astrocytes induced by LPS. Finally, targeting Smad1 abrogated BMP10-induced hypersensitivity and activation of astrocytes.

Conclusion

These findings indicate that the BMP10/ALK2/Smad1/5/8 axis plays a key role in pain hypersensitivity after peripheral nerve injury, which indicates its stimulative ability toward astrocytes.

Exploring viral neuropathic pain: Molecular mechanisms and therapeutic implications

As the Coronavirus Disease 2019 (COVID-19) pandemic continues, there is a growing concern regarding the relationship between viral infections and neuropathic pain. Chronic neuropathic pain resulting from virus-induced neural dysfunction has emerged as a significant issue currently faced. However, the molecular mechanisms underlying this phenomenon remain unclear, and clinical treatment outcomes are often suboptimal. Therefore, delving into the relationship between viral infections and neuropathic pain, exploring the pathophysiological characteristics and molecular mechanisms of different viral pain models, can contribute to the discovery of potential therapeutic targets and methods, thereby enhancing pain relief and improving the quality of life for patients. This review focuses on HIV-related neuropathic pain (HNP), postherpetic neuralgia (PHN), and neuropathic pain caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infections, examining rodent models and relevant cellular molecular pathways. Through elucidating the connection between viral infections and neuropathic pain, it aims to delineate the current limitations and challenges faced by treatments, thereby providing insights and directions for future clinical practice and research.

The mutual effect of progesterone and vitamin D in an animal model of peripheral nerve injury

Background and purpose

Experimental and clinical studies have shown the potential role of progesterone in relieving neural injury. In addition, emerging data on vitamin D, a steroid hormone, have shown its neuroprotective properties. This study was designed to evaluate the mutual effect of vitamin D and progesterone on neuropathic pain (NP) in male rats.

Experimental approach

Chronic constriction injury (CCI) was induced by inserting four ligatures around the sciatic nerve. Hyperalgesia and allodynia (cold and mechanical) were considered positive behavioral scores of NP. After surgery, Sprague Dawley male rats (weighing 200-250 g) were assigned into 7 groups. Vitamin D (250 and 500 units/kg/day, i.p.) and progesterone (4 and 6 mg/kg/day, i.p.) were injected from the 1st day after CCI which continued for 21 days. Moreover, one group received the co-administration of vitamin D (500 units/kg/day, i.p.) and progesterone (6 mg/kg/day, i.p.) from the 1st day until the 21st post-CCI day. Behavioral tests were performed on the 7th, 14th, and 21st days.

Findings/Results

Daily supplementation with vitamin D (250 and 500 units/kg) did not alter nociception. Progesterone (4 and 6 mg/kg/day) was ineffective on thermal hyperalgesia. In the allodynia test, progesterone significantly decreased pain-related behaviors. The co-administration of vitamin D (500 units/kg/day) with progesterone (6 mg/kg/day) significantly relieved thermal hyperalgesia. Finally, the combination significantly decreased cold and mechanical allodynia.

Conclusion and implications

This study showed the mutual effect of progesterone and vitamin D on NP for the first time. Hyperalgesia and allodynia were significantly relieved following co-administration of vitamin D and progesterone.

Prevalence and management of chronic nonmalignant pain in palliative care populations: A systematic review

OBJECTIVES

To investigate the prevalence and current approaches to clinical management of chronic nonmalignant pain in patients referred to palliative care services.

METHODS

A systematic review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and registered with PROSPERO (CRD42021205432). Six databases were searched on 25 August 2020 and again on 11 July 2022: PubMed and Ovid MEDLINE, Elsevier Scopus, PsychINFO, the Cochrane Library, and CINAHL. Search included prevalence or intervention studies with patients who had chronic nonmalignant pain and were referred to palliative care services. Screening was undertaken independently by 2 reviewers.

RESULTS

The searches returned 417 titles; subsequent screening identified 5 eligible studies, 4 from the USA and 1 from Hong Kong, including 2 cohort and 3 cross-sectional studies. Sample sizes ranged from 137 to 323, with a total of 1,056 patients. The prevalence of chronic nonmalignant pain ranged from 14% to 34% across different palliative care settings. There was significant crossover of pain types; 54% of patients with chronic no-malignant pain had additional cancer-related pain or cancer treatment-related pain. Opioids were used to manage stand-alone chronic nonmalignant pain for 39% of patients compared to 58% with mixed chronic nonmalignant pain and other pain diagnoses.

SIGNIFICANCE OF RESULTS

Five studies have documented the prevalence of chronic nonmalignant pain of 14-34% in palliative care. Further research including prevalence and treatment studies would provide clearer evidence for best practice management of chronic nonmalignant pain in the palliative care setting.

Prevalence of radicular neuropathic pain in idiopathic Parkinson's disease: A systematic review and meta-analysis

Parkinson's disease (PD) is estimated to impact up to 1 % of the global population aged 60 years and older. Among the non-motor manifestations of idiopathic PD, radicular neuropathic pain emerges as a noteworthy concern due to its potential for debility in affected individuals. In, this systematic review and meta-analysis we aimed to evaluate the prevalence of radicular neuropathic pain and thus provide evidence of how this painful symptom affects the lives of patients with idiopathic PD. We registered the research protocol for this study in PROSPERO (CRD42022327220). We searched the Embase, Scopus, and PubMed platforms for studies on PD and neuropathic pain until April 2023. The search yielded 36 articles considered to have a low risk of bias. The prevalence of radicular neuropathic pain in patients with PD was 12.7 %, without a difference when we consider the duration of diagnosis (cut-off < 7 years) or levodopa dosage (cut-off <600 mg/dL). Moreover, there was no variation in the prevalence of radicular neuropathic pain regarding a Hoehn and Yahr stage cut-off of <2.5 or >2.5. Of note, a limited number of patients received pain treatment (21.5 %). We also found that the source of publication bias is the use of the Ford criteria (FC), suggesting that this type of diagnostic criteria may contribute to an underdiagnosis of radicular neuropathic pain in patients with PD. This study underlines the necessity for a more discerning and comprehensive approach to the diagnosis and management of radicular neuropathic pain in patients with idiopathic PD.

Pulsed Radiofrequency in the Management of Postsurgical Abdominal Wall Chronic Pain: A Report From a Single Oncological Center

Chronic postsurgical pain (CPSP) is defined as pain that develops or increases in intensity after a surgical procedure or tissue injury and persists beyond the healing process, lasting at least three months after the precipitating event. Often neuropathic in nature, CPSP can be challenging to manage. CPSP is a common complication, with data suggesting an incidence ranging from 5% to 85%, depending on the type of procedure. Meralgia paresthetica (MP) and ilioinguinal/iliohypogastric neuralgias (IH/IL N) are two possible clinical scenarios of CPSP following lower abdominal procedures. Pulsed radiofrequency (PRF) is a minimally invasive technique of peripheral neuromodulation effective in various pain etiologies; however, evidence is scarce regarding its use in MP and IH/IL N. This case series aims to assess the potential role of PRF in the management of CPSP following abdominal wall procedures. This case series was set in a single oncological center between January 2017 and February 2022 and included adult patients (>18 years old) referred to our unit with a high suspicion of postsurgical MP or IH/IL N refractory to conservative treatment. PRF was performed after a positive diagnostic block in patients whose pain could not be controlled despite optimal medical treatment. The efficacy of PRF was assessed regarding pain intensity using the verbal numeric scale (VNS) and the duration of pain relief in weeks. The follow-up period was from the initial PRF procedure to the end of data collection. Parametric data were presented as mean and standard deviation (SD), and non-parametric data as median (minimum-maximum). Seventeen patients were included: 82.35% (n=14) were female, and the mean age was 58.0 ± 11.35 years. MP was present in 47.1% (n=8) and IH/IL N in 52.9% (n=9). Transverse rectus abdominis muscle flap reconstruction (TRAM) was the most common procedure (n=5, 29.41%). Diagnostic blocks were performed in 88.24% (n=15) of the patients. Initial VNS scores were 7.59 ± 2.62; 2.82 ± 2.62 at 24 hours; and 2.47 ± 1.58 at 15 days. During follow-up, 70.59% (n=12) of patients had no recurrence of initial symptoms. A second PRF was performed in 29.41% (n=5) cases based on the recurrence of symptoms, following a mean period of pain relief of 112 (8-238) weeks. No major or minor complications were identified during early or late follow-up. PRF can be a useful tool to improve the multimodal management of postsurgical abdominal wall chronic pain.

Peripheral and central neurobiological effects of botulinum toxin A (BoNT/A) in neuropathic pain: a systematic review

ABSTRACT

Botulinum toxin (BoNT), a presynaptic inhibitor of acetylcholine (Ach) release at the neuromuscular junction (NMJ), is a successful and safe drug for the treatment of several neurological disorders. However, a wide and recent literature review has demonstrated that BoNT exerts its effects not only at the "periphery" but also within the central nervous system (CNS). Studies from animal models, in fact, have shown a retrograde transport to the CNS, thus modulating synaptic function. The increasing number of articles reporting efficacy of BoNT on chronic neuropathic pain (CNP), a complex disease of the CNS, demonstrates that the central mechanisms of BoNT are far from being completely elucidated. In this new light, BoNT might interfere with the activity of spinal, brain stem, and cortical circuitry, modulating excitability and the functional organization of CNS in healthy conditions. Botulinum toxins efficacy on CNP is the result of a wide and complex action on many and diverse mechanisms at the basis of the maladaptive plasticity, the core of the pathogenesis of CNP. This systematic review aims to discuss in detail the BoNT's mechanisms and effects on peripheral and central neuroplasticity, at the basis for the clinical efficacy in CNP syndromes.

Exploring the Analgesic Initiation Mechanism of Tuina in the Dorsal Root Ganglion of Minor CCI Rats via the TRPV1/TRPA1-cGMP Pathway

Tuina is a treatment method in traditional Chinese medicine which has analgesic effects and effectively alleviates the symptoms of neuropathic pain (NP). Transient receptor potential vanilloid type 1 (TRPV1) and transient receptor potential ankyrin type 1 (TRPA1) play major roles in transmitting nociceptive sensory signals in the nociceptive primary sensory dorsal root ganglion (DRG) nerve. The nitric oxide (NO)/cyclic guanosine 3',5'-monophosphate(cGMP) pathway exerts both nociceptive and antinociceptive effects in various chronic pain models. TRPV1 and TRPA1 mediate the influx of calcium, which stimulates the generation of NO. Subsequently, NO activates the NO/cGMP/protein kinase G (PKG) signaling pathway, thereby improving hyperalgesia. In the present study, oa rat model of NP with minor chronic constriction injury (CCI) of the right sciatic nerve of NP was established. The results of behavioral testing showed that, after a one-time tuina intervention, the mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were prolonged to varying degrees in the tuina group compared with the model group. Similarly, the expression of TRPV1, TRPA1, NO, soluble guanylate cyclase β (sGCβ), cGMP, and PKG1 was significantly decreased in the DRG of the tuina and tuina + TRPV1/TRPA1 antagonist group was significantly decreased. These findings suggest that the tuina intervention can effectively improve the symptoms of thermal and mechanical allodynia caused by peripheral nerve injuries. Tuina exerts immediate analgesic effects through the TRPV1/TRPA1-NO-cGMP-PKG signaling pathway.

Immune response and cytokine profiles in post-laminectomy pain syndrome: comparative analysis after treatment with intrathecal opioids, oral opioids, and non-opioid therapies

INTRODUCTION

This study explores the interaction between cytokines, cell-mediated immunity (T cells, B cells, and NK cells), and prolonged morphine administration in chronic neuropathic pain patients without cancer-related issues. Despite evidence of opioid immunomodulation, few studies have compared these interactions.

METHODS

In a cross-sectional and comparative study, 50 patients with chronic low back radicular pain ("Failed Back Surgery Syndrome") were categorized into intrathecal morphine infusion (IT group, n = 18), oral morphine (PO group, n = 17), and non-opioid treatment (NO group, n = 15). Various parameters, including plasma and cerebrospinal fluid (CSF) cytokine concentrations, lymphocyte immunophenotyping, opioid escalation indices, cumulative morphine dose, and treatment duration, were assessed.

RESULTS

CSF IL-8 and IL-1β concentrations exceeded plasma levels in all patients. No differences in T, B, and NK lymphocyte numbers were observed between morphine-treated and non-treated patients. Higher plasma IL-5 and GM-CSF concentrations were noted in IT and PO groups compared to NO. CSF IFNγ concentrations were higher in PO and NO than IT. Positive correlations included CD4 concentrations with opioid escalation indices, and negative correlations involved NK cell concentrations, CSF TNFα concentrations, and opioid escalation indices. Positive correlations were identified between certain cytokines and pain intensity in IT patients, and between NK cells and cumulative morphine dose. Negative correlations were observed between CSF IL-5 concentrations and pain intensity in IT and PO, and between opioid escalation indices and CSF cytokine concentrations in PO and IT.

CONCLUSION

Associations between cytokines, cellular immunity, and prolonged morphine treatment, administered orally and intrathecally were identified.

Understanding public perceptions and discussions on diseases involving chronic pain through social media: cross-sectional infodemiology study

BACKGROUND

Chronic pain is a highly prevalent medical condition that negatively impacts quality of life and is associated with considerable functional disability. Certain diseases, such as fibromyalgia, headache, paraplegia, neuropathy, and multiple sclerosis, manifest with chronic pain.

OBJECTIVE

The aim of this study is to examine the number and type of tweets (original or retweet) related to chronic pain, as well as to analyze the emotions and compare the societal impact of the diseases under study.

METHODS

We investigated tweets posted between January 1, 2018, and December 31, 2022, by Twitter users in English and Spanish, as well as the generated retweets. Additionally, emotions were extracted from these tweets and their diffusion was analyzed. Furthermore, the topics most frequently discussed by users were collected.

RESULTS

A total of 72,874 tweets were analyzed, including 44,467 in English and 28,407 in Spanish. Paraplegia represented 23.3% with 16,461 of the classified tweets, followed by headache and fibromyalgia with 15,337 (21.7%) and 15,179 (21.5%) tweets, respectively. Multiple sclerosis generated 14,781 tweets (21%), and the fewest tweets were related to neuropathy with 8,830 tweets (12.5%). The results showed that the primary emotions extracted were "fear" and "sadness." Additionally, the reach and impact of these tweets were investigated through the generated retweets, with those related to headaches showing the highest interest and interaction among users.

CONCLUSION

Our results underscore the potential of leveraging social media for a better understanding of patients suffering from chronic pain and its impact on society. Among the most frequently encountered topics are those related to treatment, symptoms, or causes of the disease. Therefore, it is relevant to inform the patient to prevent misconceptions regarding their illness.

Ursolic acid molecules dock MAPK1 to modulate gut microbiota diversity to reduce neuropathic pain

To investigate the efficacy of Ursolic acid in alleviating neuropathic pain in rats with spinal nerve ligation (SNL), the SNL rat model was surgically induced. Different concentrations of Ursolic acid and manipulated target mitogen-activated protein kinase 1 (MAPK1) were administered to the SNL rats. Fecal samples were collected from each group of rats for 16S rDNA analysis to examine the impact of gut microbiota. Molecular docking experiments were conducted to assess the binding energy between Ursolic acid and MAPK1. In vivo studies were carried out to evaluate the expression of inflammatory factors and signaling pathways in spinal cord and colon tissues. Ursolic acid was found to have a beneficial effect on pain reduction in rats by increasing plantar withdrawal latency (PWL) and paw withdrawal threshold (PWT). Comparing the Ursolic acid group with the control group revealed notable differences in the distribution of Staphylococcus, Allobaculum, Clostridium, Blautia, Bifidobacterium, and Prevotella species. Network pharmacology analysis identified MAPK1 and intercellular adhesion molecule-1 (ICAM1) as common targets for Ursolic acid, SNL, and neuropathic pain. Binding sites between Ursolic acid and these targets were identified. Additionally, immunofluorescent staining showed a decrease in GFAP and IBA1 intensity in the spinal cord along with an increase in NeuN following Ursolic acid treatment. Overexpression of MAPK1 in SNL rats led to an increase in inflammatory factors and a decrease in PWL and PWT. Furthermore, MAPK1 counteracted the pain-relieving effects of Ursolic acid in SNL rats. Ursolic acid was found to alleviate neuropathic pain in SNL rats by targeting MAPK1 and influencing gut microbiota homeostasis.

Outcomes of Trigeminal Ganglion Sparing Surgical Resection of Nonacoustic Cerebellopontine Angle Tumors Causing Trigeminal Neuralgia

OBJECTIVE

Tumors may be responsible for up to 5% of trigeminal neuralgia cases. Predictors of long-term pain relief after surgical resection of various cerebellopontine angle tumor types are not well understood. Previous studies found that size and extent of resection predict long-term pain status, although resection of tumor involving the trigeminal ganglion may be associated with high morbidity. This study evaluated predictors of TN pain freedom after resection of a nonacoustic CPA tumor, with avoidance of any portion involving the TG.

METHODS

In a retrospective cohort study, we evaluated clinical outcomes and complications after surgical resection of nonacoustic CPA tumors with purposeful avoidance of the TG causing trigeminal neuralgia. The primary outcome was pain-freedom. We performed logistic regression analyses to examine the relationship between pain-freedom at last follow-up and age, side of symptoms, preoperative symptom duration, tumor diameter, tumor type, and concurrent neurovascular compression (NVC).

RESULTS

Of 18 patients with nonacoustic CPA tumors causing TN treated with surgical resection, 83.3% were pain-free at last follow-up (mean 44.6 months). Age (P = 0.12), side (P = 0.41), preoperative symptom duration (P = 0.85), tumor diameter (P = 0.29), tumor type (P = 0.37), and NVC presence (P = 0.075) were not associated with long-term pain freedom.

CONCLUSIONS

This study provides additional evidence that various tumor types causing TN may safely undergo surgical resection and decompression of the trigeminal nerve to treat TN. This study presents a cohort of patients that underwent resection of a nonacoustic CPA tumor, with purposeful avoidance of the TG to minimize complications, demonstrating high rates of long-term pain freedom.

Age and Sex Differences in Pediatric Neuropathic Pain and Complex Regional Pain Syndrome: A Scoping Review

BACKGROUND

Age and sex differences may exist in the frequency (incidence, prevalence) or symptoms of neuropathic pain (NP) and complex regional pain syndrome (CRPS) due to biopsychosocial factors (eg, neurodevelopment, physiological and hormonal changes, psychosocial differences) that evolve through childhood and adolescence. Age and sex differences may have implications for evaluating screening and diagnostic tools and treatment interventions.

OBJECTIVE

To map the existing literature on pediatric NP and CRPS with respect to age and sex distributions, and age and sex differences in symptomology and frequency.

METHODS

A scoping literature review was conducted. Databases were searched from inception to January 2023. Data were collected on study design, setting, demographics, and age and sex differences in frequency and symptoms.

RESULTS

Eighty-seven studies were included. Distribution of participants with CRPS (n=37 studies) was predominantly early adolescence (10 to 14 y) and female sex, while NP (n=42 studies) was most commonly reported throughout adolescence (10 to 19 y) in both sexes. Forty-one studies examined age and sex differences in frequency; 6 studies reported higher frequency in adolescence. Very few studies (n=11) examined differences in symptomology.

DISCUSSION

Large epidemiological studies are required to further understand age and sex differences in frequency of pediatric NP and CRPS. Age and sex differences must be considered when evaluating screening and diagnostic tools and treatment interventions to ensure relevance and validity to both sexes and across ages. Validated tools will improve understanding of age-dependent and sex-dependent differences in symptoms, pathophysiology, and psychosocial impact of pediatric NP and CRPS.

Pain in Parkinson disease: a deep phenotyping study

ABSTRACT

In our prospective cross-sectional study, we comprehensively characterized Parkinson disease (PD)-related pain in monocentrically recruited patients with PD using standardized tools of pain assessment and categorization. One hundred fifty patients were systematically interviewed and filled in questionnaires for pain, depression, motor, and nonmotor symptoms. Patients with PD-related pain (PD pain), patients without PD-related pain (no PD pain), and patients without pain (no pain) were compared. Pain was present in 108/150 (72%) patients with PD, and 90/150 (60%) patients were classified as having PD-related pain. Most of the patients with PD (67/90, 74%) reported nociceptive pain, which was episodic (64/90, 71%), primarily nocturnal (56/90, 62%), and manifested as cramps (32/90, 36%). Parkinson disease-related pain was most frequently located in the feet (51/90, 57%), mainly at the toe joints (22/51, 43%). 38/90 (42%) patients with PD-related pain received analgesic medication with nonsteroidal anti-inflammatory drugs being the most frequently used (31/42, 82%) and opioids most effective (70% pain reduction of individual maximum pain intensities, range 22%-100%, confidence interval 50%-90%). All patients received oral PD treatment; however, levodopa equivalent dose showed no correlation with mean pain intensities (Spearman ρ = 0.027, P > 0.05). Our data provide a comprehensive analysis of PD-related pain, giving evidence for mainly non-neuropathic podalgia, which bears the potential to rethink assessment and analgesic treatment of pain in PD in clinical practice.

Silencing of FTO inhibits oxidative stress to relieve neuropathic pain by m6A modification of GPR177

BACKGROUND

Neuropathic pain (NP) is a challenging health condition owing to its complex nature and associated multiple etiologies. The occurrence of NP involves the abnormal activity of neurons mediated by oxidative stress (OS). Previous research has demonstrated that m6A methylation plays a role in the regulatory pathway of NP. This study aimed to investigate the specific molecular pathways through which m6A methylation modifiers alleviate NP.

METHODS

For this purpose, an NO rat model was developed via spared nerve injury (SNI), followed by quantifying the animal's pain assessment via paw withdrawal threshold (PWT) and paw withdrawal latency (PWL). The OS in SNI rats was evaluated by measuring reactive oxygen species, superoxide dismutase, and catalase (CAT) in spinal cord tissues. Moreover, quantitative-real-time polymerase chain reaction and western blot analysis were employed for detecting fat mass and obesity-associated (FTO) and GPR177 levels, while m6A levels of GPR117 were analyzed via MeRIP.

RESULTS

The results indicated an enhanced OS with highly expressed FTO in spinal cord tissue samples, where knocking down Fto effectively relieved NP and OS in SNI rats. Mechanistic investigations revealed that Fto-mediated reduction of Grp177 m6A modification was involved in the WNT5a/TRPV1 axis-mediated OS remission of NP. Moreover, in vitro experiment results indicated that YTHDF2 was an important m6A methylated reading protein for this process.

CONCLUSIONS

Fto silencing leads to increased m6A methylation of Grp177 through a YTHDF2-dependent mechanism, resulting in decreased Grp177 stability and ultimately reducing NP in rats by OS suppression.

Cultivating Comfort: Examining Participant Satisfaction with Hypnotic Communication Training in Pain Management

Context

One in four Canadians experiences chronic pain, yet insufficient services and restrictions surrounding prevailing treatments result in inadequate management and significant negative consequences for these individuals. Previous work indicates that hypnotic communication represents a promising complementary treatment; however, training protocols for healthcare professionals are underdeveloped and understudied.

Aim

To evaluate the level of satisfaction for a training program on hypnotic communication in pain management clinics.

Design

Qualitative study.

Methods

Six health professionals who first completed the hypnotic communication training participated in 30 minutes virtual semi-structured interviews. These testimonials allowed them to elaborate on their user experience and potential areas for improvement. Thematic analysis using qualitative data management software NVIVO was conducted on the interview data.

Results

Two themes emerged from the interviews. 1) Satisfaction: Participants expressed satisfaction on various structural aspects of the training, including the provided materials, atmosphere, training structure, presentation modalities, practical workshops, acquired knowledge, trainer quality, and training duration. 2) Areas for Improvement: Five main improvement suggestions were identified (providing more material; more practical workshops, more concrete and adapted; testimonials from former patients; follow-up training meeting; and continuing education).

Implications for the Profession and/or Patient Care and Conclusion

The results improved the training program to help minimized inherent biases related to this technique, cut associated costs, and identify reasons that would explain its underutilization among medical professionals in Quebec. Our work highlights that healthcare professionals in chronic pain management clinics (eg, respiratory therapists, nurses) can incorporate this simple hypnotic communication technique into their usual care and contribute to the well-being of patients.

Impact

This study aimed to address the lack of training protocols for healthcare professionals, that are underdeveloped and understudied. The main findings on participant' satisfaction and the areas of improvement for the training will help the refinement of the training to better suit healthcare professional's needs in hospitals and chronic pain facilities.

Comparison of Magnetic Resonance Imaging with Electrodiagnosis in the Evaluation of Clinical Suspicion of Lumbosacral Radiculopathy

(1) Background: The diagnosis of lumbosacral radiculopathy involves anamnesis, an assessment of sensitivity and strength, diagnostic imaging-usually magnetic resonance imaging (MRI)-and electrodiagnostic testing (EDX), typically electromyography (EMG), and electroneurography (ENG). MRI evaluates the structures supporting the spinal cord, while EDX evaluates root functionality. The present study aimed to analyze the concordance of MRI and EDX findings in patients with clinically suspected radiculopathy. Additionally, we investigated the comparison between these two reference tests and various clinical variables and questionnaires. (2) Methods: We designed a prospective epidemiological study of consecutive cases with an observational, descriptive, cross-sectional, and double-blind nature following the STROBE guidelines, encompassing 142 patients with clinical suspicion of lumbosacral radiculopathy. (3) Results: Of the sample, 58.5% tested positive for radiculopathy using EDX as the reference test, while 45.8% tested positive using MRI. The comparison between MRI and EDX in the diagnosis of radiculopathy in patients with clinical suspicion was not significant; the overall agreement was 40.8%. Only the years with symptoms were comparatively significant between the positive and negative radiculopathy groups as determined by EDX. (4) Conclusion: The comparison between lumbar radiculopathy diagnoses in patients with clinically suspected pathology using MRI and EDX as diagnostic modalities did not yield statistically significant findings. MRI and EDX are complementary tests assessing different aspects in patients with suspected radiculopathy; degeneration of the structures supporting the spinal cord does not necessarily imply root dysfunction.

Repetitive transcranial magnetic stimulation in central post-stroke pain: a meta-analysis and systematic review of randomized controlled trials

Background

The rehabilitation of central post-stroke pain (CPSP) is a complex clinical challenge, and repetitive transcranial magnetic stimulation (rTMS) has been widely applied in the research of neurofunctional recovery following stroke. However, there is currently no reliable evidence-based medicine supporting the efficacy of rTMS in central post-stroke pain. This review aims to evaluate the effects of rTMS on central post-stroke pain.

Methods

Following the PRISMA guidelines, we conducted searches on PubMed, Cochrane Library, Embase, Web of Science, CNKI, and Wan Fang Data Knowledge Service Platform. We searched for randomized controlled trials (RCTs) investigating the use of rTMS in treating central post-stroke pain, and conducted screening based on inclusion and exclusion criteria. Characteristics of the included RCTs were extracted. The heterogeneity of the trials was assessed using the I2 statistic. Meta-analysis was performed using Stata 17 software. Bias risk and methodological quality were evaluated using the Cochrane RoB 2 tool and the Pedro scale.

Results

A total of six randomized controlled trials involving 288 patients met our inclusion criteria. In our analysis, rTMS was more effective in treating patients with CPSP compared to the placebo group (SMD=-1.15, 95% CI: -1.69, -0.61, P < 0.001). Furthermore, results from subgroup analysis indicated no statistically significant difference in the improvement of pain for durations exceeding 6 months when comparing rTMS to conventional treatment (SMD=-0.80, 95% CI: -1.63, 0.03, P = 0.059).

Conclusion

TMS can alleviate pain in CPSP patients and improve their motor function, but its effects on depression, anxiety, and MEP-latency are not significant.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, CRD42024497530.

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).

A Narrative Review of the Dorsal Root Ganglia and Spinal Cord Mechanisms of Action of Neuromodulation Therapies in Neuropathic Pain

Neuropathic pain arises from injuries to the nervous system in diseases such as diabetes, infections, toxicity, and traumas. The underlying mechanism of neuropathic pain involves peripheral and central pathological modifications. Peripheral mechanisms entail nerve damage, leading to neuronal hypersensitivity and ectopic action potentials. Central sensitization involves a neuropathological process with increased responsiveness of the nociceptive neurons in the central nervous system (CNS) to their normal or subthreshold input due to persistent stimuli, leading to sustained electrical discharge, synaptic plasticity, and aberrant processing in the CNS. Current treatments, both pharmacological and non-pharmacological, aim to alleviate symptoms but often face challenges due to the complexity of neuropathic pain. Neuromodulation is emerging as an important therapeutic approach for the treatment of neuropathic pain in patients unresponsive to common therapies, by promoting the normalization of neuronal and/or glial activity and by targeting cerebral cortical regions, spinal cord, dorsal root ganglia, and nerve endings. Having a better understanding of the efficacy, adverse events and applicability of neuromodulation through pre-clinical studies is of great importance. Unveiling the mechanisms and characteristics of neuromodulation to manage neuropathic pain is essential to understand how to use it. In the present article, we review the current understanding supporting dorsal root ganglia and spinal cord neuromodulation as a therapeutic approach for neuropathic pain.

Pathology of pain and its implications for therapeutic interventions

Pain is estimated to affect more than 20% of the global population, imposing incalculable health and economic burdens. Effective pain management is crucial for individuals suffering from pain. However, the current methods for pain assessment and treatment fall short of clinical needs. Benefiting from advances in neuroscience and biotechnology, the neuronal circuits and molecular mechanisms critically involved in pain modulation have been elucidated. These research achievements have incited progress in identifying new diagnostic and therapeutic targets. In this review, we first introduce fundamental knowledge about pain, setting the stage for the subsequent contents. The review next delves into the molecular mechanisms underlying pain disorders, including gene mutation, epigenetic modification, posttranslational modification, inflammasome, signaling pathways and microbiota. To better present a comprehensive view of pain research, two prominent issues, sexual dimorphism and pain comorbidities, are discussed in detail based on current findings. The status quo of pain evaluation and manipulation is summarized. A series of improved and innovative pain management strategies, such as gene therapy, monoclonal antibody, brain-computer interface and microbial intervention, are making strides towards clinical application. We highlight existing limitations and future directions for enhancing the quality of preclinical and clinical research. Efforts to decipher the complexities of pain pathology will be instrumental in translating scientific discoveries into clinical practice, thereby improving pain management from bench to bedside.

Spinal Cord Stimulation in Refractory Postherpetic Neuralgia in Portugal: A Case Report

Postherpetic neuralgia is one of the most severe complications after herpes zoster infection. Patients who experience persistent pain despite conservative treatment may benefit from interventional therapies, such as spinal cord stimulation. We present the case of a patient with severe refractory postherpetic neuralgia in the right T8 to L1 distribution who responded effectively to spinal cord stimulation. After its implantation, the patient had improvements in pain intensity, pain-related interference, quality of life, and satisfaction, with a simultaneous reduction of previous medications. This case report highlights the role of spinal cord stimulation in refractory neuropathic pain secondary to herpes zoster.

Prevalence and patterns of neuropathic pain in people with chronic post-surgical pain after total knee arthroplasty

Aims

The aim of this study was to describe the prevalence and patterns of neuropathic pain over one year in a cohort of patients with chronic post-surgical pain at three months following total knee arthroplasty (TKA).

Methods

Between 2016 and 2019, 363 patients with troublesome pain, defined as a score of ≤ 14 on the Oxford Knee Score pain subscale, three months after TKA from eight UK NHS hospitals, were recruited into the Support and Treatment After Replacement (STAR) clinical trial. Self-reported neuropathic pain and postoperative pain was assessed at three, nine, and 15 months after surgery using the painDETECT and Douleur Neuropathique 4 (DN4) questionnaires collected by postal survey.

Results

Symptoms of neuropathic pain were common among patients reporting chronic pain at three months post-TKA, with half reporting neuropathic pain on painDETECT (191/363; 53%) and 74% (267/359) on DN4. Of those with neuropathic pain at three months, half continued to have symptoms over the next 12 months (148/262; 56%), one-quarter had improved (67/262; 26%), and for one-tenth their neuropathic symptoms fluctuated over time (24/262; 9%). However, a subgroup of participants reported new, late onset neuropathic symptoms (23/262; 9%). Prevalence of neuropathic symptoms was similar between the screening tools when the lower cut-off painDETECT score (≥ 13) was applied. Overall, mean neuropathic pain scores improved between three and 15 months after TKA.

Conclusion

Neuropathic pain is common in patients with chronic pain at three months after TKA. Although neuropathic symptoms improved over time, up to half continued to report painful neuropathic symptoms at 15 months after TKA. Postoperative care should include screening, assessment, and treatment of neuropathic pain in patients with early chronic postoperative pain after TKA.

A Mixed Methods Approach to Explore the Experience of Pain and Its Management in People with Parkinson's Disease

Introduction

Pain in Parkinson's disease (PD) is common but poorly understood, with most research to date taking a mechanistic approach. This mixed methods study takes a broader biopsychosocial approach to assess and describe contributors of pain and explore pain management and the relationship between pain and physical activity in people with PD (PwPD) and chronic pain.

Methods

A structured survey evaluated respondents' contributors of pain using standardized, self-report assessments of the following: pain, peripheral neuropathy, central nociplastic change, emotional dysregulation or pathology, and maladaptive cognitions. Semistructured individual interviews were conducted with purposively sampled survey participants and analyzed using inductive thematic analysis.

Results

Eighty-nine PwPD (mean age 67 years, 55% female) completed the survey. The most common pain contributors were maladaptive cognitions (62%), central nociplastic change (49%), and emotional dysregulation (44%). Approaches to pain management and the response to physical activity were variable within and across individuals with different pain contributors. Four themes emerged from interviews with 24 participants: (1) causative perceptions of pain are diverse; (2) sense of control influences disease acceptance and exercise self-efficacy; (3) belief in the value of therapy; and (4) pain as the unspoken PD symptom. Physical activity was used by PwPD for pain management; however, the relationship between pain and physical activity varied based on sense of control.

Conclusions

Clinicians should screen for pain and assess its contributors to provide individualized, multidimensional pain management that considers the biological, psychological, and social factors of pain in PwPD. It is plausible that such an approach would promote a better sense of control for PwPD.

Long-term pain outcomes after serial lidocaine infusion in participants with recent onset of peripheral neuropathic pain: A pilot double-blind, randomized, placebo-controlled trial

BACKGROUND

This study investigated the outcomes up to 12 weeks after serial lidocaine infusion for early-onset peripheral neuropathic pain.

METHODS

This pilot double-blind, randomized, 2-arm placebo-controlled trial recruited 50 participants with onset of peripheral neuropathic pain within the past 6 months and randomized them to either receive lidocaine (3 mg/kg) in normal saline (50 mL) intravenous infusion over 1 hour (lidocaine group) once a week for 4 weeks or 50 mL of normal saline infusion (placebo group) once a week for 4 weeks. Twenty-nine participants completed the protocol; 15 participants were assigned to the lidocaine group and 14 to the placebo group. The outcomes were pain intensity assessed using a numerical rating scale (NRS), quality of life assessed using EuroQol-Five Dimensions-Five Levels questionnaire (EQ-5D-5L), psychological function using the Thai version of the 21-item Depression Anxiety Stress Scales (DASS-21), pain medication use, and adverse effects, all assessed at baseline (BL) and again at 4, 8, and 12 weeks following randomization.

RESULTS

The reported tramadol use at 8 and 12 weeks following the first infusion was significantly lower in the lidocaine group (P = .023). No other significant between-group differences were observed at any time point or for any other outcome, and no serious adverse events were observed.

CONCLUSION

Multiple lidocaine infusions of 3 mg/kg once a week for 4 weeks in participants with recent onset of peripheral neuropathic pain demonstrated no significant benefits in pain intensity, quality of life, or psychological outcomes. At most, this treatment may result in less tramadol use.

Ligusticum chuanxiong Hort. Ameliorates Neuropathic Pain by Regulating Microglial M1 Polarization: A Study Based on Network Pharmacology

Background

In traditional Chinese medicine, Ligusticum chuanxiong Hort. (LCH) is used to treat neuropathic pain (NP). This study was performed to investigate the underlying pharmacological mechanisms.

Methods

The main components of the LCH were obtained from the TCMSP database. The targets of the active components were obtained using the Swiss Target Prediction database and HERB database. The NP-related genes were obtained from the CTD database and GeneCard database. Protein-protein interaction (PPI) network was constructed using the STRING platform and Cytoscape 3.9.0 software. GO and KEGG enrichment analyses were performed using the DAVID database. Interactions between the key components and hub target proteins were verified using molecular docking and molecular dynamics simulation. In addition, microglial cell line HMC3 was induced to polarize to the M1 phenotype using 100 ng/mL lipopolysaccharide (LPS). Quantitative real-time polymerase chain reaction (qRT-PCR), Western blot and enzyme-linked immunosorbent assays were used to detect the expression levels of M1 markers and inflammatory factors, respectively.

Results

Seven LCH active components of LCH were identified, corresponding to 387 target genes. 2019 NP-related genes were obtained, and a total of 174 NP-related genes were identified as target genes that could be modulated by LCH. Beta-sitosterol, senkyunone, wallichilide, myricanone, and mandenol were considered as the key components of LCH in the treatment of NP. SRC, BCL2, AKT1, HIF1A and HSP90AA1 were identified as the hub target proteins. GO analysis showed that 328 biological processes, 61 cell components, and 85 molecular functions were likely modulated by the components of LCH, and KEGG enrichment analysis showed that 132 signaling pathways were likely modulated by the components of LCH. Beta-sitosterol, senkyunone, wallichilide, myricanone, and mandenol showed good binding activity with hub target proteins including SRC, BCL2, AKT1, and HSP90AA1. In addition, beta-sitosterol inhibited LPS-induced M1 polarization in HMC3 in vitro.

Conclusion

This study provides a theoretical basis for the application of LCH in the treatment of NP through multicomponent, multitarget, and multiple pathways.

Emotion Processing in Peripheral Neuropathic Pain: An Observational Study

BACKGROUND

In clinical practice, the implementation of tailored treatment is crucial for assessing the patient's emotional processing profile. Here, we investigate all three levels of analysis characterizing emotion processing, i.e., recognition, representation, and regulation, in patients with peripheral neuropathic pain (PNP).

METHODS

Sixty-two patients and forty-eight healthy controls underwent quantitative sensory testing, i.e., psychophysical tests to assess somatosensory functions such as perception of cold (CDT), heat-induced pain (HPT), and vibration (VDT), as well as three standardized tasks to assess emotional processing: (1) the Ekman 60-Faces Test (EK-60F) to assess recognition of basic facial emotions, (2) the Reading the Mind in the Eyes Test (RME) to assess the ability to represent the feelings of another person by observing their eyes, and (3) the 20-item Toronto Alexithymia Scale (TAS-20) to assess emotional dysregulation, i.e., alexithymia.

RESULTS

General Linear Model analysis revealed a significant relationship between left index finger VDT z-scores in PNP patients with alexithymia. The RME correlated with VDT z-scores of the left little finger and overall score for the EK-60F.

CONCLUSIONS

In patients with PNP, emotion processing is impaired, which emphasizes the importance of assessing these abilities appropriately in these patients. In this way, clinicians can tailor treatment to the needs of individual patients.