Frontiers in Pain Research

Objective: To evaluate the clinical efficacy of non-invasive electrical pulsed radiofrequency (PRF) stimulation on diagnostic thresholds and subjective pain in chronic, pedal diabetic peripheral neuropathy (DPN). Methods: A randomized, single-blind, placebo-controlled trial (ClinicalTrials.gov: NCT07725419) enrolled 92 patients with pedal DPN naive to PRF and scoring [&ge;] 4/10 on the Douleur Neuropathique 4 (DN4) test. Participants received either active PRF stimulation (n = 46) or a non-stimulating placebo (n = 46) applied bilaterally to the sciatic nerve in the popliteal fossa for 10 minutes per limb, once weekly for three weeks. The primary outcome was clinical neuropathic resolution (DN4 < 4). Secondary outcomes included subjective pain tracking via the Brief Pain Inventory-Short Form (BPI-SF) Worst Pain scale over a 6-month follow-up window. Missing data were handled via Non-Responder Imputation (NRI). Longitudinal continuous trajectories were modeled using Linear Mixed-Effects Models (LMMs) adjusted for age, gender, and baseline medication use. Results: In the Intention-to-Treat population (N = 92), a significant diagnostic responder effect occurred at 3 months, with 39.1% of active patients dropping below the diagnostic threshold for neuropathy (DN4 < 4) versus 19.6% of placebo controls (p = 0.039). For subjective pain, 47.7% of active patients achieved a Minimally Clinically Important Difference ([&ge;] 3-point reduction) in BPI Worst Pain at 1 month compared to 19.4% of placebo controls (p = 0.008). Multivariable logistic regression identified active treatment as a significant independent predictor of clinical response (Adjusted OR = 4.86; 95% CI: 1.56 to 17.53; p = 0.010). Continuous LMM tracking confirmed a statistically significant treatment-by-timepoint interaction for BPI Worst Pain at 1 month (p = 0.046). Conclusion: A brief, three-week course of non-invasive PRF stimulation serves as a safe, effective, non-pharmacological adjunct that aids in managing the diagnostic presentation of neuropathic pain and mitigates worst pain experiences in patients suffering from pedal DPN.

Background: Neuropathic pain (NP) remains a therapeutic challenge, with conventional repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex (M1) yielding a response rate of approximately 40%. Personalised targeting based on dysfunctional neurocircuitry offers a promising strategy to enhance efficacy, yet its application in NP is unexplored. This open-label trial investigated a novel targeting approach guided by the recently described cingulo-opercular and somato-cognitive action (CON-SCAN) network, a circuit integrating cognitive and affective dimensions of pain. Methods: Twenty patients with NP received 10 sessions of M1-rTMS over two weeks, with the stimulation site individually localised based on maximal functional connectivity to a CON template. Results: Increased CON-SCAN connectivity from baseline to post-treatment was associated with reduction in pain interference, anxiety and depression scores. The response rate was 50% post-treatment, which was maintained at the 1-month follow-up. Improvements were also observed in neuropathic pain symptoms, negative affect, and overall health. Conclusions: As the first connectivity-guided rTMS trial for NP, this study provides preliminary evidence that personalised targeting of the CON-SCAN network is feasible and associated with the analgesic effects of M1-rTMS, supporting further investigation in randomised controlled trials. Trial registration: Chinese Clinical Trial Registry, ChiCTR2500104679. Registered 20 June 2025, http://www.chictr.org.cn. Chinese Clinical Trial Registry, ChiCTR2400094568. Registered 24 December 2024, http://www.chictr.org.cn. Keywords: Personalised TMS; Pain; M1; CON; SCAN

Background: Fluctuations in pain intensity are intrinsic to non-specific chronic low back pain (nsCLBP). Nevertheless, pain fluctuations have rarely been considered when investigating pathophysiological mechanisms. Therefore, a novel study protocol was developed and implemented to systematically assess the impact of fluctuating pain states on pain-related measures. Methods: The final study cohort consisted of 45 nsCLBP patients and 47 age- and sex-matched healthy controls (HCs). Patients participated in three visits, conducted during different pain states (i.e. clinically relevant pain, low-intensity clinical pain / pain-free, clinically irrelevant pain induced using a Qutenza 8% capsaicin patch). Pain fluctuations were monitored through online assessments every four days and guided the pseudorandomized visit scheduling. HCs participated in a single visit. Each study visit comprised a multimodal battery of pain-related measures. Results: 93.33% of patients completed all three visit types in a pseudorandomized order (chi-squared=1.50, p=0.826). Visit scheduling was possible due to the high self-report adherence (median=93.48%), unrelated to self-report burden (rho=-0.097, p=0.53). Study visits were conducted during different pain states, as indicated by: i) the significantly higher low back pain intensity in the clinically relevant pain visit (mean[SD]: 3.98[0.90]), compared to the low-intensity clinical pain (1.03[0.86]) and clinically irrelevant pain (1.13[0.82]) visits (p-values<0.001), as well as by ii) the successful induction of a moderate-to-high clinically irrelevant pain across assessments. Conclusion: Despite scheduling complexity and pain state transition uncertainty, a pain state-dependent pseudorandomized study design is feasible and could improve the understanding of nsCLBP mechanisms.

Background: Pain relief is the principal patient-centered goal of surgery for symptomatic lumbar synovial facet cysts, yet comparative reviews have often emphasized cyst recurrence. Whether adding fusion improves postoperative pain or reduces later surgery remains uncertain. Objective: To compare decompression alone with decompression plus fusion, with postoperative back- and leg-pain outcomes as the primary domain. Methods: PubMed, Embase, Scopus, Web of Science, and the Cochrane Library were searched from inception to 2 June 2026. Comparative cohorts and case series with at least five patients were eligible. Twenty-two studies were re-extracted for VAS/NRS scores, change scores, and persistent or recurrent pain. Random-effects restricted maximum likelihood models with Hartung-Knapp inference were used; clinically distinct pain outcomes were analyzed separately. Results: Twenty-two studies (16 cohorts, 6 case series; 51,899 participants) were included. Two studies provided compatible final VAS data. Fusion did not improve postoperative back pain (MD -0.04, 95% CI -0.17 to 0.10; I2=0%) or leg pain (MD -0.03, 95% CI -0.28 to 0.21; I2=0%). Postoperative back pain (RR 0.58, 95% CI 0.14-2.30) and leg/radicular symptoms (RR 0.75, 95% CI 0.42-1.32) were also not significantly reduced. Fusion decreased confirmed cyst recurrence (RR 0.29, 95% CI 0.15-0.57) but not reoperation or subsequent lumbar surgery (RR 0.80, 95% CI 0.42-1.50). Conclusion: Current comparative evidence does not demonstrate superior postoperative pain control with routine fusion. Fusion reduces cyst recurrence without clearly reducing reoperation, supporting selective use when instability is present or anticipated.

The Acute to Chronic Pain Signatures (A2CPS) project is a large, multisite, longitudinal observational study designed to identify biomarkers that predict the transition from acute to chronic pain following surgery in more than 2200 patients. Two participant cohorts were recruited before undergoing either knee arthroplasty or thoracic surgery. A unique feature of this study is its comprehensive evaluation of pain, including evoked and recall pain measures collected at baseline, 6-weeks, and 3-months following surgery, in addition to the primary pain outcome assessed remotely at 6 months. This paper describes the acquisition, quality control procedures, and available pain and pain sensitivity variables included in the A2CPS study. Self-report pain assessments include surgical site (i.e., index) pain intensity, pain interference and quality, spatial distribution of pain using body maps, and pain-related dysfunction specific to each cohort. Quantitative sensory testing yielded evoked pain sensitivity data including pressure pain thresholds, temporal summation of pain, dynamic mechanical allodynia, and conditioned pain modulation at both index and common sites across cohorts. Movement-evoked pain was assessed for each cohort using relevant functional tasks (knee: 10m walk and five-time-sit-to-stand tests, thoracic: deep breathing and coughing). Using baseline data from release v2.1.0, comprising approximately 1,400 participants, we evaluated interrelationships among pain variables. Overall, the A2CPS pain and pain sensitivity data provide a robust, comprehensive set of variables that supports the study goal of uncovering predictive biomarkers of post-operative chronic pain and enables broader exploration relative to other study outcomes, including imaging, psychosocial, and omics data.

Chronic widespread pain (CWP) is highly prevalent among minoritized adults with clinical obesity, and symptom management is challenging. Weight loss via bariatric surgery is often recommended to improve musculoskeletal pain. However, there is significant variation in pain trajectories following bariatric surgery, and the impact of weight loss on movement-evoked pain is largely unknown. The current study aims to systematically characterize and quantify longitudinal changes in pain at rest and movement-evoked pain up to 6 months post-surgery, and to determine whether pain modulatory mechanisms, joint motion, and mechanical loading biosignatures mediate the relationship between weight loss and pain change. This study protocol details the research methodologies and procedures for a prospective observational cohort study of 60 individuals undergoing bariatric surgery for weight loss. Participants will complete questionnaires, anthropometric measurements, clinical and experimental pain testing, functional testing, and a standardized movement testing battery to assess joint motion and mechanical loading using camera-based motion capture before and at 3 and 6 months post-bariatric surgery. Generalized linear mixed models to assess the significance of changes in PAR, MEP, and all patient-reported outcome measures. Reduced models will treat the main effect of time as a fixed factor, and intra-individual repeated measures as random effects. Ethics and dissemination: This study protocol has been registered as an observational study with ClinicalTrials.gov (NCT0675386) in the United States and has been approved by the NYU Langone Health Institutional Review Board (IRB#: i21-01652) and the New York City Health + Hospitals/Bellevue Research Office (Bellevue Study ID #: STUDY00003739). Study results will be published in peer-reviewed journals and presented at national and international conferences and community events.

Objective: To describe the self-reported effects of incobotulinumtoxinA treatments on migraine-like headache in participants who experienced traumatic brain injury versus Anomalous Health Incidents. Background: Persistent headache attributed to traumatic injury to the head has been widely recognized as among the most common sequelae of concussion/mild traumatic brain injury. Such persistent headaches often have migraine-like characteristics and are typically treated similarly to idiopathic migraine. Patients who have experienced Anomalous Health Incidents have also commonly reported migraine-like headaches, but to our knowledge, no reports describing treatment for persistent headaches attributed to Anomalous Health Incidents have been published. Methods: We describe the self-reported effects of incobotulinumtoxinA treatments on headache with migraine-like characteristics in 19 participants with traumatic brain injury and 11 who had experienced Anomalous Health Incidents from a single center. Results: Self-reported benefits from incobotulinumtoxinA treatments were generally similar and statistically indistinguishable between groups. The Headache Impact Test-6 score decreased by a mean of 12 points in the traumatic brain injury group and 9.5 points in the Anomalous Health Incidents group from baseline to peak efficacy (p = 0.43), with concomitant reductions in work/school hours lost (62% vs. 50%) and family/leisure hours lost (75% vs. 33%). Furthermore, reductions in headache frequency (67% for the traumatic brain injury group vs. 57% for the Anomalous Health Incidents group), headache severity (36% vs. 23%), headache duration (37% vs. 50%), nausea/vomiting (50% vs. 25%), photophobia (34% vs. 29%), phonophobia (30% vs. 37%), visual aura (50% vs. 29%), vestibular aura (50% vs. 33%), and other aura (21% vs. 25%) from baseline to peak efficacy were similar in both groups. Likewise, time from treatment to response (6.5 vs. 7 days), duration of response (10.2 vs. 9.1 weeks), adverse effects (3/19 for the traumatic brain injury group, 3/11 for the Anomalous Health Incidents group), and improved efficacy of concomitant abortive treatments (30% vs. 50% for pain, 50% vs. 55% for aura) did not differ between groups. Osmophobia and cogniphobia, when present, did not improve on average in either group. Notably, the mean duration of response was less than 12 weeks in both groups, with only 3 participants with traumatic brain injury and 1 participant who had experienced Anomalous Health Incidents reporting benefit beyond the typical 12-week incobotulinumtoxinA treatment interval. Conclusion: Overall, these findings provisionally indicate that at least some patients who have experienced Anomalous Health Incidents may subjectively benefit from incobotulinumtoxinA treatment for persistent migraine-like headaches similarly to patients with traumatic brain injury. Limitations include the open-label, single-center, primarily retrospective design; small sample size; and limited representativeness. Further prospective controlled studies are needed to determine whether these groups truly respond similarly to incobotulinumtoxinA and other standard treatments.

Background: Vertebroplasty and balloon kyphoplasty are used for symptomatic vertebral hemangiomas, although comparative evidence is limited. We summarized pain relief, cement leakage, and recurrence after vertebral augmentation and assessed whether direct comparison of the two techniques was feasible. Methods: Five databases were searched from inception to January 2, 2026, with an update on July 5, 2026. Because only one small cohort directly compared vertebroplasty with kyphoplasty, outcomes were pooled as single-arm proportions or, for early pain change, as a mean difference using random-effects models. Prespecified subgroup, sensitivity, small-study effect, and influence analyses were performed. Results: Forty-four studies were included: 33 case series, 10 cohort studies, and one randomized trial. Kyphoplasty-specific evidence comprised one dedicated series and one comparative cohort. Any cement leakage occurred in 10.5% of patients (14 studies; 95% CI 5.7-18.4%), while trim-and-fill gave an exploratory adjusted estimate of 20.4%. Early pain reduction averaged 5.13 points on a 0-10 scale (8 studies; 95% CI 4.48-5.77; I2=89.4%). Complete or near-complete pain relief occurred in 79.4% of patients (10 studies), and recurrence, progression, or retreatment occurred in 3.9% (13 studies). Symptomatic cement leakage was uncommon at 0.4%. Conclusion: The available literature, which is mainly retrospective and vertebroplasty-based, supports substantial pain relief with infrequent symptomatic complications. Kyphoplasty data remain insufficient for a reliable technique comparison. Prospective studies with standardized clinical and imaging outcomes are needed.

Understanding the complex network that regulates pain is fundamental to develop strategies to combat its growing prevalence and increase useful therapeutics. Although extensive literature identifies the importance of cannabinoid receptors and endocannabinoids in controlling pain, their efficacy and loci of action remain debated. To directly test the actions of peripherally restricted cannabinoids and elucidate the minimal circuitry capable of producing cannabinoid-mediated analgesia, we utilized a novel genetic approach that allows for cell-specific reactivation of cannabinoid receptor 1 (CB1R) selectively in peripheral sensory neurons using newly developed CB1R floxed-stop-floxed mice (CB1RLOXTB) crossed with Nav1.8-cre mice (Nav1.8+/-:CB1RLOXTB). Ex vivo and in vivo experiments confirmed successful knockout and reactivation of CB1R. Wildtype littermate controls, but neither Nav1.8+/-:CB1RLOXTB nor CB1RLOXTB animals, exhibited robust analgesia after systemic WIN55,212-2 (WIN) treatment in the tail flick assay. Furthermore, the presence of CB1R on Nav1.8 neurons was not associated with either a difference in the development of inflammatory pain or the response to WIN. However, after neuropathic injury, CB1RLOXTB animals displayed an earlier onset of both mechanical and thermal hypersensitivity than their Nav1.8+/-:CB1RLOXTB or wildtype counterparts, suggesting a dual role for CB1R in inflammatory and neuropathic pain. These studies represent an important approach to further improve our mechanistic understanding of cannabinoid modulation of pain in the nervous system and begins to settle long-standing controversies in cannabinoid literature. Table of ContentsPeripherally restricted cannabinoids show strong preclinical analgesic efficacy but have not translated clinically. Using a genetic model restricting CB1R to Nav1.8-expressing sensory neurons, we show peripheral neuronal endocannabinoid signaling is required for chronic, but not acute pain modulation. This dissociation suggests clinical failures may reflect testing peripheral cannabinoids in acute rather than chronic pain paradigms, informing future translational strategies.

Background: Late-onset neutropenia (LON) is an infrequently reported, unpredictable side effect of anti-CD20 therapy, with incidence varying by agent, diagnosis, and screening protocol. Objective: The primary objective of this cross-sectional, retrospective study was to estimate the proportion of patients who developed LON over 13 months (April 2023-April 2024). Methods: Consecutive adult patients diagnosed with central nervous system (CNS) autoimmunity who received at least one rituximab(RTX) or ocrelizumab(OCR) infusion between January 2016 and March 2024 were included; patients who switched to another immunotherapy, had no post-treatment blood draw, or had unverifiable infusion records were excluded. LON events were assessed using all post-treatment CBCD blood draws during this period. Results: A total of 171 patients were enrolled: 141 received rituximab and 30 received ocrelizumab. A total of 319 post-treatment blood tests were performed. Sixteen patients (16/171) had neutropenia (9.4%, 95% CI 5.8-14.7): 12 on rituximab (8.5%) and 4 on ocrelizumab (13.3%; p=0.487). LON occurred at a median of 158 days (130-188) since the last infusion. All patients were asymptomatic, mostly had Grade 1 neutropenia (15/16, 93.8%). BMI (22.2 vs. 27.5 kg/m2, p=0.001) and prior natalizumab exposure (37.5% vs. 14.2%, p=0.023) were significantly different between neutropenic and non-neutropenic patients. Conclusion: The proportion of patients with LON in this cohort was higher than most previously reported, with all cases asymptomatic. Lower BMI and prior natalizumab exposure emerged as potential risk factors warranting further investigation. Larger, prospective studies with standardized surveillance are needed to establish the true frequency and risk factors.

Background: Homeless individuals are disproportionately affected by limited access to primary care and pain management services. While community-based organizations frequently conduct outreach, few have ethical, standardized, or replicable methods for assessing pain and distributing referrals in field settings. Existing models range from passive, meals-only outreach, to costly mobile clinics with limited reach. This leaves a critical gap that a low-resource, agile framework is designed to address. Objective: The aim of this quality-improvement initiative was to implement and iteratively refine a standardized, field-based pain assessment and response pathway for adults experiencing homelessness and to evaluate its feasibility, fidelity, safety, and operational barriers during routine outreach. Methods: A cross-sectional quality improvement needs assessment was conducted during homeless outreach activities in San Francisco and Sacramento using convenience sampling. The intervention framework incorporated volunteer training, cognitive capacity screening, verbal informed consent, vital sign collection, and predefined criteria for emergency escalation. Participants were unsheltered adults with adequate decisional capacity to provide voluntary informed consent. Results: The dataset included 193 encounters, with valid pain scores for 175 participants. Mean pain was 3.79 plus or minus 2.78, with a median of 3. Cold packs were used for acute discomfort and foot or ankle pain, while hot packs were used for joint pain. Some participants declined comfort measures. No supply shortages, referral confusion, or emergency-escalation delays were documented. Telephone access remained a barrier to referral completion. Conclusion: This framework demonstrates a replicable and ethically grounded model for field-based pain assessment and referral during homeless outreach. The pathway was feasible and safe to implement, expanded care options beyond default emergency-department referral by directing stable nonemergent pain toward primary care, and identified limited telephone access as a major barrier to completing follow-up.

Background Chronic postsurgical pain (CPSP) affects between 7-23% and 13-44% of patients after hip and knee arthroplasty, respectively. Standardised methods of pain assessment provide superior evaluation of pain, including the Oxford Joint Score Pain Subscale (OJS-PS). We aim to estimate the proportion of patients with a phenotype consistent with CPSP through a k-medoids clustering technique and identify a threshold on the OJS-PS to highlight such patients at a population level. Methods In this cross-sectional study Patient Reported Outcomes Measures data 6-months after hip and knee arthroplasty from 2017 to 2025 were examined. An adapted k-medoid clustering technique utilising subsampling, batch assignment and probabilistic consensus allocated clusters. A receiver operator characteristic analysis identified a threshold on the OJS-PS noting the lowest scoring cluster. Our categorisation was compared to self-reported severe or moderate pain; sensitivity, specificity and accuracy of this categorisation were calculated. Results We analysed 109,542 hip and 113,799 knee arthroplasty patients; three clusters were used in each analysis. After hip arthroplasty: 14.4% of patients were assigned to the cluster with the lowest median OJS-PS of 11 [IQR 8 - 13]. A threshold of 15.5 classified patients as severe or moderate pain with 60.6% sensitivity, 91.0% specificity and 85.7% accuracy. Similarly, after knee arthroplasty, 25.3% were assigned to the cluster with the lowest median OJS-PS of 14 [IQR 11 - 16]. A threshold of 18.5 on the OJS-PS had an 85.4% sensitivity, 88.4% specificity and 87.8% accuracy for classifying patients with self-reported severe or moderate pain. Conclusions This robust and scalable clustering technique on ordinal clinical data estimates the proportion of patients reporting a phenotype consistent with CPSP. On a population level the thresholds identified on the OJS-PS could aid screening for potential CPSP patients 6 months after hip and knee arthroplasties.

In human dorsal root ganglia (DRG), and trigeminal (TG) neurons, the various voltage-gated sodium channel (Nav) isoforms play critical roles in the firing of action potentials, which drive electrical impulses that encode somatosensations including, itch, and pain. The SCN11A gene encodes the tetrodotoxin (TTX)-resistant voltage-gated sodium channel Nav1.9, characterized by unique gating properties. Unlike other isoforms, the Nav1.9 channel activates and inactivates slowly and has a hyperpolarized voltage-dependence of activation and depolarized voltage-dependence of inactivation. This leads to a large window current that has been suggested to function as a regulator of the resting membrane potential of neurons. Mutations in Nav1.9 channels lead to congenital insensitivity to pain (gain-of-function) or familial episodic pain syndrome (loss-of-function) suggesting the channel is a critical mediator of pain. Despite its relevance in pain pathophysiology, most existing data relies on rodent models or heterologous expression systems, leaving the specific pharmacology and biophysical behavior of these channels in human primary neurons largely unknown. In this study, we pharmacologically isolated and characterized native Nav1.9 channel currents in human DRG and TG neurons to compare their biophysical profiles. Our findings reveal significant kinetic and voltage-dependent differences between the two populations. Specifically, Nav1.9 channels in TG neurons exhibit a right-shifted steady-state inactivation curve, a larger window current, and faster activation kinetics compared to those in DRG neurons. In addition, conditions that simulate inflammatory states in-vivo greatly potentiates the Nav1.9 currents consistent with similar observations in rodent models. By detailing these distinct biophysical properties, this research offers crucial insights into Nav1.9 channel function relevant for drug discovery efforts aimed at developing analgesics for both acute and chronic pain.

Background: People with disabilities (PWD) represent over one-quarter of the US population and disproportionately experience chronic pain, yet limited research explores disparities they face in opioid use disorder (OUD) treatment. Objective: To examine disparities across disability status regarding opioid use disorder (OUD)-related outcomes and understand how chronic pain interacts with these associations. Methods: We completed a cross-sectional, secondary analysis of data from the All of Us Research Program, including 370,722 adults with electronic health record data available between January 2021-September 2023. We identified prevalence of disability, chronic pain, OUD, receipt of medications for OUD (MOUD), and OUD remission using diagnostic codes. We performed interaction analyses between chronic pain, disability subtype, and MOUD receipt in affecting OUD outcomes. Results: OUD was more common among individuals with physical (aOR: 2.74, 95% CI: 2.54-2.95), cognitive (2.19, 1.94-2.45), and multiple disabilities (2.43, 2.19-2.68), compared to those without disabilities. Among patients with OUD, those with physical disabilities were less likely to receive MOUD (0.81, 0.69-0.94). Compared to those without disabilities, chronic pain was associated with higher probabilities of OUD diagnosis and lower probabilities of MOUD and OUD remission across all subjects. These relationships were stronger for OUD diagnosis in cognitive disabilities, MOUD in multiple disabilities, and OUD remission in physical disabilities. Conclusions: Disability and chronic pain jointly shape disparities in OUD treatment and underscore the urgent need for care models that integrate OUD treatment with pain management and address the unique access challenges faced by people with disabilities.

Introduction: Functional Neurological Disorder (FND) affects women approximately three times more often than men. This disparity has largely been attributed to higher trauma prevalence and diagnostic bias, while the potential contribution of hormonal influences has received little attention. Methods: An online questionnaire was distributed through FND clinics in thirteen countries, assessing self-reported symptom change across five hormonal events: hormonal contraception, pregnancy, the menstrual cycle, menopause, and gender-affirming hormone therapy. Eligible participants were cisgender women with a diagnosis of FND, or gender minority individuals (transgender or non-binary). Perceived symptom change was rated on a five-point scale ranging from large improvement to large worsening. Results: Among 262 respondents (96% female; mean age 39 years), several hormonal contexts were associated with self-reported symptom changes. Overall, hormonal contraception and pregnancy were frequently associated with worsening of motor and cognitive symptoms, and menopause with worsening across all symptom domains. Menstrual cycle analysis revealed a phase-dependent pattern: worsening was most frequently reported during menstruation and the luteal phase, whereas improvement was most frequent during the follicular phase. Reported changes were not uniform, with a substantial proportion of participants describing no change or improvement. Conclusion: Self-reported FND symptom severity appears to vary with hormonal context, with motor and cognitive symptoms most consistently affected. Given the retrospective, self-report design, these findings are hypothesis-generating and support prospective research into the role of hormonal transitions in FND.

Spinal cord stimulation (SCS) is an established therapy for neuropathic pain, typically delivered at either low (60 Hz) or high (1 kHz) frequencies, with analgesic effects largely dependent on active stimulation. Here, we investigated whether combined-frequency SCS produces sustained analgesia beyond stimulation periods and explored the underlying mechanisms. Using a spared nerve injury (SNI) model in both rats and mice, we applied dual-frequency SCS (60 Hz + 1 kHz). This paradigm produced robust reversal of mechanical allodynia during stimulation and, notably, a progressive and long-lasting analgesic effect that persisted for days to weeks after stimulation cessation. RNA sequencing revealed pronounced immune-related transcriptional changes in the spinal cord, including upregulation of innate immune, pro-resolution, and neutrophil-associated pathways. Functional studies demonstrated that neutrophil depletion attenuated SCS-induced analgesia, whereas intrathecal S100A8 treatment mimicked therapeutic effects via CD69/SOCS3 signaling. These findings identify dual-frequency SCS as a promising strategy to prolong analgesia and highlight a critical role for neuroimmune modulation in sustained pain relief. HighlightsO_LICombined-frequency, not single-frequency SCS, sustains analgesia during washout C_LIO_LICombination SCS induces robust immune activation in spinal cord and DRG C_LIO_LICombination SCS increases spinal perfusion and promotes neutrophil recruitment C_LIO_LINeutrophil signaling contributes to sustained SCS analgesia C_LI

Nerve growth factor (NGF) is a key mediator of pain through activation of the high-affinity tropomyosin receptor kinase A (TrkA) and the low-affinity neurotrophin receptor (p75NTR). Although neuronal TrkA signaling is well established, the contribution of non-neuronal cells to NGF- dependent pain remains unclear. Here, we show that NGF and its precursor proNGF engage distinct cellular mechanisms. Intraplantar NGF induced acute nociception, heat hyperalgesia, mechanical allodynia, and cold hypersensitivity, whereas cleavage-resistant proNGF selectively evoked mechanical allodynia and cold hypersensitivity. Pharmacological and cell-specific genetic approaches demonstrated that acute nociception and heat hyperalgesia require neuronal TrkA, whereas mechanical and cold hypersensitivity depend on p75NTR activation in Schwann cells. In Schwann cells, NGF and proNGF induced p75NTR-dependent calcium release, followed by TRPA1 activation, mitochondrial ROS production, and NOX1-dependent oxidative amplification. Inhibition of ROS or TRPA1, or Schwann cell-specific Trpa1 deletion, markedly reduced mechanical allodynia and cold hypersensitivity without affecting acute nociception or heat hyperalgesia. These findings identify a Schwann cell p75NTR-ROS-TRPA1 pathway sustaining persistent pain and highlight non-neuronal p75NTR signaling as a potential therapeutic target.

Accurate assessment of pain in animal models is essential for understanding pain mechanisms, developing analgesics, and ensuring animal welfare. The Mouse Grimace Scale (MGS) provides a sensitive, non-invasive measure of spontaneous pain by quantifying pain-related facial expressions, but its utility is limited by labor-intensive manual scoring, observer variability, and reliance on static images that fail to capture the temporal dynamics of facial behavior. Existing automated approaches improve throughput but typically rely on highly standardized imaging conditions, selected viewing angles, and static facial appearance, while providing limited temporal resolution and little insight into the relative contributions of individual facial action units. Here, we introduce LabGrymace, an open-source, artificial intelligence-powered framework for automated, frame-by-frame analysis of pain-related facial dynamics in freely moving mice. Built on the LabGym behavioral analysis platform, LabGrymace uses deep-learning-based facial feature detection and tracking to quantify ear, eye, and nose movements continuously from video recordings. To generate a quantitative pain metric and facilitate reproducibility, we calibrated facial dynamics against graded chemogenetic activation of nociceptors and identified the kinematic features most strongly associated with pain intensity. These features were integrated into a weighted composite pain score that reflects the differential contributions of individual facial action units. LabGrymace accurately classified pain-related facial actions and generated continuous pain scores without manual frame selection or restrictive recording conditions. The resulting pain scale exhibited dose-dependent responses generalized across distinct pain modalities, including visceral pain induced by MgSO and somatic pain induced by capsaicin. By combining automated facial-feature analysis with quantitative temporal modeling, LabGrymace provides an objective, scalable, interpretable, and flexible tool for assessing spontaneous pain in laboratory mice.

Background: In Denmark, perioperative high-dose glucocorticoid treatment were step-wisely implemented for total hip arthroplasty (THA), total knee arthroplasty (TKA), and unicompartmental knee arthroplasty (UKA). We aimed to estimate the effect of a single high dose of glucocorticoids on opioid consumption following primary THA, TKA, and UKA. Methods: This was a prespecified analysis of a multicenter natural experiment using electronic health record data. We included elective THA, TKA, or UKA surgeries performed in Eastern Denmark from 2017-2025. At each center, surgeries before implementation of high-dose glucocorticoids served as controls, whereas surgeries after implementation comprised the intervention group. The primary outcome was the between-group difference in cumulative 0-24h opioid consumption, which included preemptive end-of-surgery doses. The predefined minimal important difference was set at 5 mg IV morphine equivalents. Secondary outcomes were maximum 0-10 numerical rating scale (NRS) pain score and incidence of opioid-related adverse events within 24 hours, hospital length of stay, and days alive and out of hospital at 30 days. Results: A total of 47,317 surgeries performed at nine centers were analyzed: 13,010 controls and 34,307 in the intervention group. During the study period, five centers implemented high-dose glucocorticoids for THA patients, two for TKA/UKA patients. High-dose glucocorticoids were administered to 6% of patients before implementation versus 92% after. High-dose glucocorticoids resulted in a mean reduction of 3.8 mg intravenous (IV) morphine equivalents (95% CI 3.3;4.3). The intervention also reduced the maximum 0-24h NRS pain score by 0.8 points (99% CI 0.7;0.9), but there was no difference in adverse events, length of stay, or days alive and out of hospital. Conclusions: Implementation of high-dose glucocorticoids reduced 0-24-hour opioid consumption by 3.8 mg IV morphine equivalents after elective hip and knee arthroplasty. This difference was below the prespecified minimal important difference threshold. Online registration: https://doi.org/10.1101/2025.11.11.25339982

Background: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for Parkinson's Disease (PD), but identifying optimal stimulation contacts is time-intensive. Beta-band activity (13-35 Hz) from local field potentials (LFP) correlates with motor symptoms and attenuation by dopaminergic therapy and DBS supports its role as a programming biomarker. The recently introduced Electrode Identifier (EI) feature of Medtronic PerceptTM neurostimulators may facilitate beta-guided contact selection. Objective: To evaluate whether pseudo-monopolar STN beta power obtained using EI predicts optimal stimulation contacts and compare its performance with reconstructed bipolar recordings and MPR. Methods: LFPs were recorded in 69 patients using EI and Electrode Survey (ES). Prediction accuracy was assessed using predefined ranking rules and compared with clinically selected contacts. Agreement between EI, ES, and MPR was evaluated. Motor outcome was assessed using MDS-UPDRS-III. Results: EI predicted clinically selected contacts above chance (TOP1: 45%, p = 0.010; TOP2-80: 57%, p = <0.001), whereas ES exceeded chance only under more inclusive selection criteria (TOP1: 38%, p = 0.073; TOP2-80: 55%, p = 0.0021). Accuracy did not differ between methods (TOP1: p = 0.720; TOP2-80: p = 1.000). EI showed highest agreement with MPR and tended to select ventral contacts. Neither method predicted motor outcome, although EI-matched contacts showed a trend toward greater improvement. Due to technical constraints, one-third of EI recordings were excluded. Conclusions: Pseudo-monopolar STN beta power provides clinically relevant information for DBS contact selection with performance comparable to bipolar approaches. Further improvements are needed before clinical implementation.