Central sensitisation in chronic pain conditions: latest discoveries and their potential for precision medicine

The pain of PTSD: integrating persistent or chronic pain within emotional processing theory of posttraumatic stress disorder

Background: Posttraumatic stress disorder (PTSD) and chronic pain are devastating conditions that often co-occur. Current understanding of comorbid PTSD and chronic pain is limited, and treatment options are undereffective.Objective: This paper presents a theoretical basis for conceptualising chronic pain symptoms within Emotional Processing Theory (EPT), the foundation for Prolonged Exposure (PE), an effective treatment for PTSD. EPT conceptualises the development and treatment of PTSD using a trauma structure that strongly overlaps with pain's neurobiology.Method: This paper proposes a model of shared aetiology and treatment of comorbid PTSD and chronic pain, emphasising these shared neurobiological underpinnings. Discussion details how the comorbidity is maintained through parallel avoidance processes focused on: (1) trauma memories and reminders in PTSD preventing reduction of negative affect (extinction) and inhibitory learning, and (2) physical pain in chronic pain fuelling increased pain and reduced function.Results: A conceptualisation is presented on how PTSD and chronic pain symptomology can be addressed within the EPT framework, increasing the confidence of providers and patients while addressing an important gap in the literature. Finally, recommendations for providers using PE with patients with PTSD and pain are provided including a case example and treatment plan based on real patients.Conclusions: This model provides a clinically useful understanding of the underlying neurobiology for the co-occurrence of PTSD and chronic pain and offers direction for future research.

Trajectories of cold but not mechanical sensitivity correspond with disability trajectories after whiplash injury

ABSTRACT

Developmental trajectories for neck disability after whiplash injury have been identified. Their relationship to cold and mechanical sensitivity trajectories is not known. We aimed to (1) identify recovery trajectories of cold and mechanical sensitivity, (2) explore their codevelopment with disability trajectories, (3) identify predictors of sensitivity trajectories, and (4) explore codevelopment of cold and mechanical sensitivity trajectories. Participants (n = 233) were assessed at <1, 3, 6, and 12 months after whiplash injury. Outcomes were cold pain detection threshold (CPT at neck), pressure pain detection thresholds (PPT, neck C5, and tibialis anterior), and the Neck Disability Index. We used group-based trajectory models to identify postinjury recovery trajectories and multinominal logistic regression to explore associations between baseline characteristics and trajectory membership. We identified the following trajectory groups: CPT (low [50.0%], moderate [29.7%], and high [20.4%] sensitivity); PPT C5 (low [10.8%] and high [89.2%] sensitivity); and PPT tibialis anterior (low [23.9%], moderate [39.0%], and high [37.1%] sensitivity); all were stable over the 12 months. There was good correspondence between disability and cold sensitivity trajectory groups but not for mechanical sensitivity; cold and mechanical sensitivity trajectories were not well associated. Higher baseline pain predicted membership of the high cold sensitivity trajectory (RR 1.27, 95% CI 1.01-1.59) and hyperarousal symptoms predicted membership of the moderate cold sensitivity trajectory (RR 1.17, 95% CI 1.01-1.36). We found no associations between baseline characteristics and mechanical sensitivity. There is an interplay between cold allodynia, pain, and hyperarousal symptoms in development of ongoing disability after whiplash injury. Different mechanisms likely underlie cold and mechanical sensitivity.

EFFECTIVENESS OF A PAIN INFORMED MOVEMENT PROGRAM IN POST COVID-19 CONDITION PATIENTS: A RANDOMIZED CONTROL TRIAL

OBJECTIVES

To evaluate the early impact of the Pain Informed Movement (PIM) program in patients with post COVID-19 condition experiencing new onset persistent pain.

DESIGN

A single-blind, 2 arm, parallel-group, randomized controlled trial.

SETTING

A public health sciences faculty.

PARTICIPANTS

Fifty-seven patients (n=57) with post COVID-19 condition were randomized into the PIM (n=27) and the control (usual care and educational booklet) groups (n=30).

INTERVENTION

Patients in the intervention group received an 8-week PIM program. Each week, participants attended 2 face-to-face sessions of 1 hour per week. The first session was group-based and focused on pain neuroscience education. The second session was individual and consisted of functional exercises and relaxation techniques. Additionally, patients were required to perform these exercises and techniques at home twice a week, recording their compliance and progress.

MAIN OUTCOME MEASURES

Measured outcomes include pain intensity and interference measured with the Brief Pain Inventory (BPI), catastrophizing assessed with the Pain Catastrophizing Scale (PCS), kinesiophobia measured with the Tampa Kinesiophobia Scale (TSK) and functionality assessed using World Health Organization Disability Assessment Schedule (WHODAS 2.0). Participants were assessed at baseline and post intervention.

RESULTS

The intervention group showed a significant reduction in all variables with respect to baseline values. In addition, the intervention group showed significant differences with respect to the control group in pain intensity (MD=2.84±0.62; p<.001; Cohen's d=1.21), pain interference (MD=3.10±0.70; p < .001; Cohen's d=1.18), catastrophizing (MD=12.52±2.48; p<.001; Cohen's d=1.34), kinesiophobia (MD=8.07±1.34; p<.001; Cohen's d=1.56) and functionality (MD=16.16±6.92; p=.039; Cohen's d=0.62).

CONCLUSIONS

In conclusion, the PIM program suggests to be an effective intervention for the reduction of new onset persistent pain and improvement of functionality in patients with post COVID-19 condition. This study underscores the importance of multidimensional and personalized approaches to persistent pain management, although more research is needed to confirm its applicability in clinical practice.

Review of Guidelines for Implantable Peripheral Nerve Stimulation (PNS) in the Management of Chronic Pain

PURPOSE OF REVIEW

This article assesses the current evidence and guidelines on peripheral nerve stimulation (PNS) and provides recommendations for its use in managing moderate to severe chronic pain.

RECENT FINDINGS

PNS has been utilized for over 50 years in the treatment of chronic pain. However, since 2015, the Food and Drug Administration (FDA) has approved percutaneously implanted PNS leads and neurostimulators, providing a minimally invasive, non-opioid alternative for managing persistent and refractory chronic pain. The American Society of Interventional Pain Physicians (ASIPP) has established evidence-based consensus guidelines for the clinical use of PNS systems in addressing chronic pain. ASIPP guidelines performed extensive evidence synthesis, including systematic reviews, randomized controlled trials (RCTs), and observational studies using Grading of Recommendations, Assessment, Development and Evaluation (GRADE) criteria or certainty of evidence, and qualitative synthesis based on the best available evidence. The evidence level and recommendations showed fair evidence with moderate strength of recommendation for implantable PNS systems following a trial or selective lumbar medial branch stimulation without a trial and for temporary PNS for 60 days. This review offers a comprehensive analysis of peripheral neuropathic pain as a cause of chronic, intractable, function-limiting, and high-impact pain. It discusses the diagnosis of peripheral nerve and neuropathic pain, evidence evaluation and synthesis, medical necessity criteria, patient education, and clinical recommendations. The goal is to enhance patient outcomes by integrating PNS technology into clinical practice.

Physical Activity as a Central Pillar of Lifestyle Modification in the Management of Chronic Musculoskeletal Pain: A Narrative Review

Objective: This narrative review aims to analyze physical activity as a central pillar of lifestyle modification in the management of chronic musculoskeletal pain by examining its effects on pain modulation as well as related lifestyle domains, including sleep, stress regulation, dietary habits, and smoking behavior. Methods: A narrative structured review was conducted. We searched MEDLINE/PubMed, Embase, and Cochrane Reviews using terms related to chronic pain and lifestyle. Randomized controlled trials, observational studies, systematic reviews, and narrative reviews reporting on the concepts of interest were included. The results were synthesized and described narratively. Results: Through the release of neuromodulatory compounds such as endorphins, endocannabinoids, dopamine, and serotonin, exercise improves analgesia, promotes emotional resilience, and reduces the reward response associated with addictive behaviors such as smoking. Its effects on the hypothalamic-pituitary-adrenal axis reduce cortisol levels, while melatonin regulation promotes circadian synchronization and deeper sleep stages. In addition, exercise modulates appetite by increasing insulin sensitivity and altering hormones such as leptin and ghrelin, contributing to appetite control and energy balance. These mechanisms support a comprehensive approach to chronic pain management. Conclusions: Physical activity is a core component of lifestyle-based chronic pain management, not only because of its analgesic effects, but also because of its positive influence on sleep, stress regulation, dietary habits, and smoking reduction. Although the available evidence is promising, more randomized controlled trials are needed to examine the effects of exercise on other healthy lifestyle behaviors, such as stress reduction, dietary modification, and smoking cessation, to consolidate its role in the comprehensive prevention and management of chronic pain.

The pain funding gap: A database analysis of pain research funding in Canada from 2008-2023

Background

One in five Canadians experiences chronic pain, at a cost of $40.3 billion in 2019. Despite this significant burden, there are few effective treatments for pain. This gap has been recognized by Health Canada, which has put forth the Action Plan for Pain in Canada. Advancing our understanding of pain mechanisms and clinical trials to identify novel therapeutics are essential to address this treatment gap. However, it remains unknown whether the recommendations of the Action Plan have increased research investments.

Methods

We investigate research investments in pain by the Canadian Institutes of Health Research (CIHR) based on publicly available data. We performed a systematic database search focused on operating funds from competitions between 2008 and 2023 and tabulated pain funding as a proportion of total CIHR operational funds granted each year. Next, we examined the proportion of pain funding across CIHR institutes aggregated across funding years.

Results

We identified 20,126 operational grants, of which 459 were pain focused. The highest level of pain funding was 3.32% in 2019, and the average (SD) was 2.13% (0.70%). Funding was stagnant from 2008 to 2023 (R 2 = 0.10, P = 0.23). The Institute of Musculoskeletal Health and Arthritis allocated the largest proportion of funding to pain research (11.40%). Eight of the 13 institutes allocated less than 1% of their operating funds to pain research.

Interpretation

In sum, CIHR pain research funding does not match the socioeconomic burden posed by pain. We propose three action items to improve pain research funding and to ultimately relieve the burden of pain in Canada.

Symptom Duration is not Related to Central Sensitization Inventory in Midportion Achilles Tendinopathy

Background

There is concern that the prolonged symptom duration commonly observed in Achilles tendinopathy may alter pain processing and lead to development of central sensitization. If true, presence of altered pain processing could explain why nearly one third of individuals with Achilles tendinopathy do not respond to gold standard treatment. Currently, the relationship between symptom duration, symptom severity, pain, and central sensitization in Achilles tendinopathy is unclear.

Purpose

The purpose of this study was assess the proportion of individuals with midportion Achilles tendinopathy who may have central sensitization, as defined by the Central Sensitization Inventory (CSI) part A questionnaire. A secondary aim was to assess the relationship between symptom duration, pain intensity, symptom severity and CSI scores.

Study Design

Cross-Sectional Study.

Methods

Individuals diagnosed with midportion Achilles tendinopathy were included (n=182, 57% female (47.3±12.7 years). Bivariate correlations were used to evaluate relationships between symptom duration (time between date of symptom onset and date of study enrollment), symptom severity (assessed by Victorian Institute of Sport Assessment-Achilles, VISA-A), and pain intensity (assessed by Patient-Reported Outcomes Measurement Information System 29, PROMIS-29) with CSI scores.

Results

Nine of 182 individuals (4.9%, 9 females) scored above the clinical cut off for CSI, indicating likely presence of central sensitization. Duration of symptoms did not correlate with CSI score (r = 0.037, 95% CI [-.109, .181] p=0.622). VISA-A had a significant negative correlation with CSI score (r=-0.293, [-.420, -.154] p<0.001), and pain intensity had a significant positive correlation with CSI score (r=0.195, [.051, .331] p=0.008).

Conclusion

Less than five percent of individuals with midportion Achilles tendinopathy met criteria for likely presence of central sensitization as defined by the CSI screening questionnaire. The study findings suggest prolonged symptom duration among those with midportion Achilles tendinopathy is unlikely to increase the occurrence of symptoms associated with central sensitization.

Level of Evidence

Level 4.

Spinal hyperexcitability in patients with chronic musculoskeletal pain or headache as evidenced by alterations in the nociceptive withdrawal reflex: a systematic review and meta-analysis

ABSTRACT

The nociceptive withdrawal reflex (NWR) is a spinal withdrawal reflex induced by painful stimulation. It is a measure of spinal hyperexcitability, which is believed to contribute to chronic musculoskeletal pain (MSKP) and headache. Previous syntheses of the evidence for alterations in the NWR in patients with chronic MSKP and headache needed a comprehensive update. This systematic review and meta-analysis was performed after the Preferred Items for Systematic reviews and Meta-Analyses guidelines. Studies examining NWR-related outcome measures in patients with chronic MSKP and headache compared to pain-free controls were identified through electronic database searches and included after screening against predefined eligibility criteria. Standardized mean differences or mean differences and 95% confidence intervals (CI) were calculated. Thirty-one studies were included in the systematic review and 25 in the meta-analysis. Moderate-quality evidence was found indicating lower NWR threshold (-3.68; 95% CI, -4.56 to -2.80; P < 0.001), larger NWR area (standardized mean difference = 0.69; 95% CI, 0.37-1.01; P < 0.001), and shorter NWR latency (mean difference = -13.68; 95% CI, -22.69, -4.67; P = 0.003) in patients compared to controls. These findings remained robust when performing meta-regressions based on subgroups (ie, headache, fibromyalgia, whiplash-associated disorder, and osteoarthritis). Low-quality evidence demonstrated facilitated temporal summation of NWR threshold (-2.48; 95% CI, -3.13 to -1.83; P < 0.001) in patients compared to controls. Spinal hyperexcitability as evidenced by lowered NWR threshold values and temporal summation of the NWR is present in patients with chronic MSKP and headache. No evidence was found for alterations in NWR duration and NWR magnitude. Future research is needed to address the gap in research on NWR-related outcome measures other than NWR threshold.

Frequency of central sensitization and nociplastic pain in patients with plantar fasciitis : Central sensitization and nociplastic pain in plantar fasciitis

PURPOSE

If the pain persists for a long time in the treatment of plantar fasciitis (PF) or if there is no response to treatment, central sensitization (CS) may develop and the pain may transform into nociplastic pain (NP). This study aimed to evaluate the frequency of CS and NP in patients with PF.

METHODS

This cross-sectional study was undertaken between November 2023 and March 2024. The Foot Function Index (FFI) scale, which evaluates the foot's functionality, was applied to the patient group. The Visual Analog Scale (VAS), which evaluates pain intensity; the Pain-DETECT scale, which evaluates NP; and the Central Sensitization Scale (CSI), which evaluates CS, were applied to patient and control groups.

RESULTS

A total of 206 people were included in the study; 106 were in the patient group with PF, and 100 constituted the control group. While we detected NP in 67 (63.2%) patients according to Pain-DETECT and CS was detected in 91 (85.8%) patients according to CSI among 106 patients with chronic PF; we detected NP in seven (7%) patients according to Pain-DETECT and CS in 44 (44.0%) patients according to CSI among 100 control patients. VAS-score and FFI-pain are moderately and positively correlated with pain-DETECT scores and fairly and positively correlated with CSI scores in the PF group. The pain-DETECT score is moderately and positively correlated with the CSI score in the two groups.

CONCLUSIONS

This is the first study to evaluate the presence of CS and NP in PF patients. We found NP and CS to be common in patients with chronic PF. Effective pain management in patients with PF before it becomes chronic can prevent the development of CS and NP.

Pain sensitivity questionnaire in endometriosis

There is increasing recognition that nociplastic pain and central sensitization may play a role in endometriosis-associated pain. The Pain Sensitivity Questionnaire Minor (PSQ-M) evaluates subjective widespread pain sensitivity, and is linked to pain outcomes in chronic pain populations. However, evidence connecting the PSQ-M to central sensitization in endometriosis is limited. Using the Central Sensitization Inventory (CSI) as a comparison, this study compared the PSQ-M as a clinical proxy for central sensitization in endometriosis individuals. Data collected from 983 endometriosis participants (mean age of 34 years), between January 2020 and December 2022, were analyzed from a prospective registry. A significant but weak positive correlation was observed between PSQ-M and CSI scores (r=0.099, p<0.001). A significant but weak correlation was found between the number of central sensitivity syndromes and pelvic pain-related comorbidities with the PSQ-M (r=0.093, p<0.001), compared to a stronger correlation with the CSI (r=0.687, p<0.05). PSQ-M scores were not significantly associated with baseline (r=0.013, p=0.797) or post-operative (r=-0.046, p=0.801) quality-of-life. There was no change in the PSQ-M and a small change in CSI after endometriosis surgery, suggesting that surgical treatment of endometriosis does not directly address central sensitization. In conclusion, the PSQ-M may not be the optimal clinical proxy for central sensitization in endometriosis. PERSPECTIVE: This study evaluates the Pain Sensitivity Questionnaire - Minor (PSQ-M) as a proxy for central sensitization in endometriosis. The PSQ-M showed weak correlations with central sensitivity syndromes and pain scores and was not associated with post-surgical quality-of-life, suggesting it may not be the optimal tool for assessing central sensitization in endometriosis.

The role of interoceptive sensibility on central sensitization to pain in vulvodynia

BACKGROUND

Interoception may be linked to central sensitization in chronic pain.

AIM

We aimed to provide evidence about the role of interoceptive sensibility on central sensitization in vulvodynia.

METHODS

In this cross-sectional study, a sample of females who received a diagnosis of vulvodynia filled out validated questionnaires relative to the individual level of interoceptive sensibility and the symptoms of central sensitization.

OUTCOMES

Interoceptive sensibility and symptoms of central sensitization were measured with the Multidimensional Assessment of Interoceptive Awareness and the Central Sensitization Inventory, respectively.

RESULTS

A lower level of trust and a higher level of emotional awareness predicted a higher number of central sensitization symptoms in our sample.

CLINICAL IMPLICATIONS

Our evidence may increase the researchers' and physicians' attention toward the involvement of the central nervous system in pain phenomenology in vulvodynia.

STRENGTHS AND LIMITATIONS

No ad-hoc control sample was collected. No behavioral assessments about interoception were performed.

CONCLUSION

As registered in other chronic pain conditions, interoceptive sensibility may play a crucial role in the expressions of symptoms of central sensitization in vulvodynia.

A Systematic Review of the Prevalence of Overactive Bladder in Women with Non-Urinary Tract Endometriosis and the Effect of Endometriosis Surgery on Symptoms of Overactive Bladder

INTRODUCTION AND HYPOTHESIS

Overactive bladder (OAB) is characterised by urinary urgency, with or without incontinence, often accompanied by daytime frequency and nocturia, in the absence of urinary tract infection or other identifiable causes. Population studies estimate the prevalence of OAB at 12.8% (EPIC study), increasing with age, reaching up to 43% after age 40. Endometriosis affects about 10% of women of reproductive age. Both OAB and endometriosis are chronic and negatively impact women's quality of life. They appear to share a common pathophysiology related to central sensitisation. We hypothesised that OAB and endometriosis might co-exist, and surgical excision of endometriosis could alleviate OAB symptoms. We aimed to assess the prevalence of OAB in patients with endometriosis and examine the effect of endometriosis surgery on OAB symptoms.

METHODS

A systematic search of MEDLINE, PubMed, Embase, and CINAHL-Plus identified studies reporting on endometriosis and OAB or overlapping conditions such as interstitial cystitis. Studies on bladder or ureteric endometriosis were excluded.

RESULTS

Six studies (772 participants) were included. The prevalence of OAB in endometriosis patients ranged from 9.4% (Brazil) to 32% (France). OAB diagnosis varied, with tools such as International Consultation of Incontinence Modular Questionnaire on Female Lower Urinary Tract Symptoms, Core Lower Urinary Tract Symptom Score, Bristol Female Lower Urinary Tract Symptoms, and urodynamics. Surgical outcomes were inconsistent, with no improvement in three studies, equivocal in one, and worsened in another.

CONCLUSION

Overactive bladder and non-urinary tract endometriosis may co-occur in 20.5% of patients, with surgery showing variable effects on OAB symptoms. Further standardised global research is warranted to fill in evidence gaps such as whether pre-operative desensitisation could improve surgical and quality-of-life outcomes.

Role of exercise on pain, functional capacity, and inflammatory biomarkers in osteoarthritis: A systematic review and meta-analysis

BACKGROUND

Osteoarthritis (OA) is a complex disease that causes pain, stiffness and swelling, limiting function and mobility, thus interfering with daily life and affecting personal, social, and psychological aspects of life.

OBJECTIVE

To evidence the role of exercise on pain reduction and the effectiveness of one type of training over another in terms of pain, functional capacity, and inflammatory biomarkers in OA.

METHODS

Studies retrieved from Web of Science, PubMed and Scopus databases were systematically reviewed. RCTs involving physical exercise interventions in participants with OA were included. The 3 main outcomes considered in the systematic review were pain, functional capacity and inflammatory biomarkers. The effects of different types of interventions (aerobic, resistance, combined, neuromuscular and others) were analysed for each outcome. Systematic review and meta-analysis were conducted following the PRISMA Statement.

RESULTS

21 studies were included in the systematic review and 11 in the meta-analysis. The meta-analysis was conducted on pain in training intervention subgroups, showing a larger effect size for neuromuscular training -2,26 (95 % CI -4,37 to -0,14). Functional capacity and inflammatory biomarkers were analysed only with a systematic review because it was not possible to estimate the efficacy of the different training protocols with a meta-analysis.

CONCLUSION

Neuromuscular training protocols seem to be the most effective in reducing pain in OA. Direct comparison of different training treatment options on functional capacity and inflammatory biomarkers for OA is not currently feasible in practice, due to the heterogeneity of the test and the small number of studies. High-quality physical exercise intervention studies are warranted to estimate their effectiveness more accurately on pain, functional capacity, and inflammatory status in OA.

PROSPERO REGISTRATION NUMBER

CRD42023481061.

Adverse Childhood Experiences and Urogenital Pain: Examining the Mediating Effects of Negative Affect and Pain Catastrophizing

BACKGROUND : Adverse childhood experiences (ACE) are associated with later psychological and somatic problems, including the emotional sequelae of adverse events (depression, anxiety, and catastrophizing) and outcomes such as chronic pain intensity and pain-related functioning. ACE have rarely been studied in women with pelvic, urogenital, and/or bladder pain (PUBP).

AIMS

Thus, we examined how childhood adversities are related to psychological and pain-related outcomes in adult women. We also tested whether negative affect and pain catastrophizing mediated the relationship between ACE and pain-related outcomes.

METHODS

A consecutive series of 310 adult women who presented at a tertiary urology center and reported PUBP completed an intake packet, which included the ACE Questionnaire as well as measures of psychological mediators and pain-related outcomes.

RESULTS

Elevated ACEs were significantly associated with higher pain interference and vaginal insertion pain, as well as significantly related to negative affect (depression and anxiety) and pain catastrophizing. Both negative affect and pain catastrophizing were found to mediate the relationship of ACE to pain intensity and interference; however, only pain catastrophizing mediated the relationship between ACE and vaginal insertion pain.

CONCLUSIONS

These results suggest that ACEs may impact some pain-related outcomes in women with PUBP by influencing negative affect and pain catastrophizing. Thus, these processes are important targets for intervention in individuals with PUBP and a history of adverse childhood events.

TRIAL REGISTRATION

This study does not require a clinical trial registration because it is not a clinical trial.

Quantifying Impairments in the Subacute Phase of Whiplash Associated Disorders-A Cross-Sectional Study

Whiplash-Associated Disorders (WADs) often result from traffic accidents, leading to persistent symptoms, including neck pain, disability, dizziness, and central sensitization (CS). A key concern is cervical range of motion (cROM) impairment and sensorimotor dysfunction, which contribute to prolonged disability. This study assessed functional performance in individuals with subacute (>1, <3 months) WADs (n = 122) compared to healthy controls (n = 45). Clinical measures included cROM, movement control (Butterfly test), and position sense (Head-Neck Relocation Test, HNRT). Patient-reported outcomes included neck disability, pain intensity, central sensitization, and dizziness. Mixed and linear models evaluated group differences and the influence of demographic and symptom-related factors. WAD patients had significantly reduced cROM and impaired movement control (p < 0.001). Neck disability (p < 0.001) and pain intensity (p = 0.015) affected cROM within the WAD group. Interaction effects revealed greater amplitude accuracy (AA) impairments at greater difficulty levels (p = 0.043), while time on target (TOT) differences decreased (p < 0.001). Dizziness was associated with increased undershoot (p < 0.001), while pain negatively impacted both AA (p = 0.003) and TOT (p = 0.037). Position sense did not differentiate WAD patients from controls. Findings suggest task-dependent sensorimotor deficits, highlighting the need for multimodal assessment. Early CS screening may optimize rehabilitation and prevent chronic disability.

Is there a correlation between length of employment and receiving a post-professional certification or residency in physical therapy? A pilot study

BackgroundVarious factors in recent years have been shown to negatively impact the physical therapy (PT) workforce in the United States, including decreased reimbursement, burnout, student debt, work-life balance, and more.ObjectiveTo determine if there is a correlation between length of employment and receiving a post-professional certification or residency training in PTMethodsA convenience sample of 121 PTs completing a post-professional certification or residency program, or none, was obtained from a large multi-clinic PT group with an accompanying educational department. Data for each of the employed PTs in the cohort was obtained regarding the hire date, duration of employment before certification/residency, since certification/residency, and overall.ResultsOnly one certification, the pain certification, was correlated to longer employment versus no formal post-professional certification/residency training (p = 0.02). Results show that the mean duration of employment before the start of a pain certification (3.67 years) was significantly longer than sports physical therapy residency (0.52 years; p = 0.001), orthopedic physical therapy residency (1.13 years; p = 0.006)) and manual therapy certification (0.81 years; (p = 0.001). Following training, employment duration produced a less pronounced difference.ConclusionEnrollment in a post-professional pain certification occurs later in the employment tenure compared to other certifications and residencies. Additional research is needed to explore the correlation between post-professional education and longevity of employment and other confounding variables.

A home-based EEG neurofeedback treatment for chronic neuropathic pain-a pilot study

Objective

This study assessed the effect of an 8-week home-based neurofeedback intervention in chronic neuropathic pain patients.

Subjects/Patients

A cohort of eleven individuals with chronic neuropathic pain receiving treatment within the NHS framework.

Methods

Participants were trained to operate a home-based neurofeedback system. Each received a portable Axon system for one week of electroencephalogram (EEG) baselines, followed by an 8-week neurofeedback intervention, and subsequent 12 weeks of follow-up EEG baselines. Primary outcome measures included changes in the Brief Pain Inventory and Visual Analogue Pain Scale at post-intervention, and follow-ups compared with the baseline. Secondary outcomes included changes in depression, anxiety, stress, pain catastrophizing, central sensitization, sleep quality, and quality of life. EEG activities were monitored throughout the trial.

Results

Significant improvements were noted in pain scores, with all participants experiencing overall pain reduction. Clinically significant pain improvement (≥30%) was reported by 5 participants (56%). Mood scores showed a significant decrease in depression (p < 0.05), and pain catastrophizing (p < 0.05) scores improved significantly at post-intervention, with continued improvement at the first-month follow-up.

Conclusion

The findings indicate that an 8-week home-based neurofeedback intervention improved pain and psychological well-being in this sample of chronic neuropathic pain patients. A randomized controlled trial is required to replicate these results in a larger cohort. Clinical Trial Registration: https://clinicaltrials.gov/study/NCT05464199, identifier: (NCT05464199).

Assessing signs of central sensitization: A critical review of physiological measures in experimentally induced secondary hyperalgesia

BACKGROUND AND OBJECTIVES

Central sensitization (CS) is believed to play a role in many chronic pain conditions. Direct non-invasive recording from single nociceptive neurons is not feasible in humans, complicating CS establishment. This review discusses how secondary hyperalgesia (SHA), considered a manifestation of CS, affects physiological measures in healthy individuals and if these measures could indicate CS. It addresses controversies about heat sensitivity changes, the role of tactile afferents in mechanical hypersensitivity and detecting SHA through electrical stimuli. Additionally, it reviews the potential of neurophysiological measures to indicate CS presence.

DATABASES AND DATA TREATMENT

Four databases, PubMed, ScienceDirect, Scopus and Cochrane Library, were searched using terms linked to 'hyperalgesia'. The search was limited to research articles in English conducted in humans until 2023.

RESULTS

Evidence for heat hyperalgesia in the SHA area is sparse and seems to depend on the experimental method used. Minimal or no involvement of tactile afferents in SHA was found. At the spinal level, the threshold of the nociceptive withdrawal reflex (RIII) is consistently reduced during experimentally induced SHA. The RIII area and the spinal somatosensory potential (N13-SEP) amplitude are modulated only with long-lasting nociceptive input. At the brain level, pinprick-evoked potentials within the SHA area are increased.

CONCLUSIONS

Mechanical pinprick hyperalgesia is the most reliable behavioural readout for SHA, while the RIII threshold is the most sensitive neurophysiological readout. Due to scarce data on reliability, sensitivity and specificity, none of the revised neurophysiological methods is currently suitable for CS identification at the individual level.

SIGNIFICANCE

Gathering evidence for CS in humans is a crucial research focus, especially with the increasing interest in concepts such as 'central sensitization-like pain' or 'nociplastic pain'. This review clarifies which readouts, among the different behavioural and neurophysiological proxies tested in experimental settings, can be used to infer the presence of CS in humans.

Innovative therapeutic strategies using ADHD medications tailored to the behavioral characteristics of patients with chronic pain

Chronic pain affects a significant portion of adults and is linked to psychosocial issues, cognitive dysfunction, and psychiatric disorders, complicating treatment. Attention deficit hyperactivity disorder (ADHD) is increasingly recognized as a contributing factor to chronic pain, particularly nociplastic pain, with a notable prevalence of comorbidity between ADHD and conditions like fibromyalgia and chronic low back pain. ADHD behaviors such as impulsivity and overactivity can exacerbate pain by leading patients to seek risky treatments or discontinue care prematurely. ADHD medications are expected to alleviate pain severity by improving associated cognitive dysfunction and addressing central sensitization, a fundamental mechanism in chronic pain. Brain abnormalities in ADHD contribute to increased spontaneous activity in the anterior cingulate cortex-posterior insular pathway due to neuroinflammation, alterations in action potential firing, and changes in transmission pathways in the spinal dorsal horn. Additionally, increased norepinephrine synthesis and reduced transmission efficiency amplify nociceptive information from the periphery and facilitate central sensitization in ADHD. Beyond typical ADHD medications like central stimulants, norepinephrine reuptake inhibitors, and alpha-2 receptor agonists, various antidepressants, mood stabilizers, antipsychotics, Parkinson's disease medications, and antidementia medications have proven effective in alleviating ADHD symptoms. These medications, effective for ADHD, may offer innovative solutions for managing chronic pain by targeting both the cognitive/behavioral dysfunction and central sensitization observed in chronic pain comorbid with ADHD. Further research into these mechanisms could lead to new, more effective pharmacological treatments for chronic pain with comorbid ADHD, a condition that is often overlooked.

Effectiveness of pain neuroscience education, motivational interviewing and cognition targeted exercise therapy in patients with chronic neck pain: protocol for a multicentre randomised controlled trial (the COGMO-AP study)

INTRODUCTION

In primary care, the prevalence of neck pain has increased substantially. Evidence regarding treatment of chronic neck pain (CNP) is scarce, and its effectiveness is not entirely proven in different stages of chronicity, nor for different types of cervical disorders. The goal of this study is to evaluate the effectiveness of a complex intervention (COGMO intervention) compared with usual practice in primary care physiotherapy to improve neck pain intensity, severity and disability in patients with CNP.

METHODS AND ANALYSIS

Design: a pragmatic cluster-randomised clinical trial design with a 12-month follow-up.

SETTING

primary care.

PARTICIPANTS

physiotherapists as randomisation unit, and patients as analysis unit.

INCLUSION CRITERIA

individuals aged 18 to 65 years suffering from moderate to severe CNP. Sample size expected: 142 patients. Recruitment: patients referred from primary care physicians to physiotherapy.

INTERVENTION

pain neuroscience education (PNE), motivational interviewing (MI) and cognition targeted exercise therapy (CTE) compared with the standard treatment in primary care.

OUTCOMES

the main variable is reduction in pain intensity; secondary variables include pain severity, conditioned pain modulation, temporal summation, neck disability, fear/avoidance behaviour, kinesiophobia, catastrophising, therapeutic alliance and quality of life. Sociodemographic information and adherence to the intervention will be recorded.

DATA COLLECTION

baseline, and follow-up at 3, 6 and 12 months.

ANALYSIS

it will follow intention-to-treat principles, and difference in percentage of subjects achieving success on the primary endpoint at 12 months. A model with multilevel analysis will be adjusted through logistic regression (being the dependent variable pain intensity, and the independent, the intervention).

ETHICS AND DISSEMINATION

Ethical approval has been awarded by the Regional Ethics Committee of Madrid (code: COGMO-AP) and the primary health care central commission of research (code: 20210011). The results of the study will be disseminated through international peer-reviewed journals, international conferences, press and social media.

TRIAL REGISTRATION NUMBER

NCT05785455.

Applying Nociplastic Pain Criteria in Chronic Musculoskeletal Conditions: A Vignette Study

Background/Objectives: The International Association for the Study of Pain (IASP) recently introduced clinical criteria and a grading system to identify nociplastic pain, marking a pivotal step toward improving diagnostic accuracy. This study aimed to evaluate the reliability and validity of the IASP criteria using clinical vignettes, assessing their effectiveness in identifying nociplastic pain in clinical settings. Methods: A reliability and diagnostic accuracy study was conducted using 32 clinical vignettes based on the literature and pre-existing clinical data. The vignettes represented patients with and without the characteristics of nociplastic pain and were reviewed independently by two expert physiotherapists. Inter-rater and intra-rater reliability were evaluated with a 1-month interval between assessments. Criterion validity was analyzed by comparing the IASP criteria against the standardized vignettes as the reference standard. Sensitivity, specificity, and predictive values were calculated to assess diagnostic accuracy. Results: The IASP criteria demonstrated moderate-to-perfect intra-rater agreement (κ = 0.71-1.00, p < 0.05) and weak-to-perfect inter-rater agreement (κ = 0.52-1.00, p < 0.05). Criterion validity was moderate (κ = 0.68), with strong specificity (89.0%) and moderate sensitivity (69.0%). Positive and negative predictive values were high at 81.8% and 81.0%, respectively, supporting the criteria's accuracy in identifying and excluding nociplastic pain. Conclusions: The IASP criteria for nociplastic pain exhibited satisfactory reliability and criterion validity in this preliminary study, particularly after initial rater familiarization. Future research should evaluate their application in real-world clinical settings, explore concurrent and prognostic validity, and involve a broader range of raters to enhance generalizability.

Update on chronic pain management

Pain is a common presenting symptom to consultant physicians, both in the hospital and in the clinic or rooms. Biologically, pain serves as warning of tissue damage. But this is no longer the case when pain is present for months or years, especially when it has been fully investigated. There can be a substantial discrepancy between the magnitude of pain, disability and distress reported by a patient with chronic pain and the extent of tissue damage identified. From the 1990s until the mid-2010s, opioids were promoted as a safe and effective panacea for chronic non-cancer pain. This led to overprescribing with unfortunate consequences of misuse, abuse and overdose deaths. The response to the so-called 'opioid epidemic' has led to a renewed focus on how chronic pain should be managed. The aim of this article is to update fellows and trainees on the assessment and management of chronic pain in adult medical patients. In particular, we address the role of pharmacotherapy post-opioid epidemic (primarily antidepressants and anticonvulsants in neuropathic pain), the place of interventional procedures and the nature and effectiveness of pain self-management training in people with chronic pain, many of whom have had pain for a year or more and failed other treatments.

Metabolic reprogramming in the spinal cord drives the transition to pain chronicity

Acute injuries can progress into painful states that endure long after healing. The mechanism underlying this transition remains unclear, but metabolic adaptations to the bioenergy demands imposed by injury are plausible contributors. Here we show that peripheral injury activates AKT/mTORC1 in afferent segments of the mouse spinal cord, redirecting local core metabolism toward biomass production while simultaneously suppressing autophagy-mediated biomass reclamation. This metabolic shift supports neuroplasticity, but creates a resource bottleneck that depletes critical spinal cord nutrients. Preventing this depletion with a modified diet normalizes biomass generation and autophagy and halts the transition to chronic pain. This effect, observed across multiple pain models, requires activation of the nutrient sensors, sirtuin-1 and AMPK, as well as restoration of autophagy. The findings identify metabolic reprogramming as a key driver of the progression to pain chronicity and point to nutritional and pharmacological interventions that could prevent this progression after surgery or other physical traumas.

Evidence of a persistent altered neural state in people with fibromyalgia syndrome during functional MRI studies and its relationship with pain and anxiety

Altered neural signaling in fibromyalgia syndrome (FM) was investigated with functional magnetic resonance imaging (fMRI). We employed a novel fMRI network analysis method, Structural and Physiological Modeling (SAPM), which provides more detailed information than previous methods. The study involved brain fMRI data from participants with FM (N = 22) and a control group (HC, N = 18), acquired during a noxious stimulation paradigm. The analyses were supported by fMRI data from the brainstem and spinal cord in FM and HC, brain fMRI data from participants with provoked vestibulodynia (PVD), and eye-tracking data from an fMRI study of FM. The results demonstrate differences in connectivity, and in blood oxygenation-level dependent (BOLD) responses, between FM and HC. In the FM group, BOLD signals underwent a large increase during the first 40 seconds of each fMRI run, prior to the application of any stimuli, compared to much smaller increases in HC. This indicates a heightened state of neural activity in FM that is sustained during fMRI runs, and dissipates between runs. The exaggerated initial rise was not observed in PVD. Autonomic functioning differed between groups. Pupil sizes were larger in FM than in HC, and the groups exhibited pupil dilation to the same levels during noxious stimulation. The initial BOLD increase varied in relation to state and trait anxiety scores. The results indicate that people with FM enter a heightened state of neural activity associated with anxiety and autonomic functioning, during every fMRI run, concurrent with increased pupil sizes, and heightened pain sensitivity. These findings may relate to the well-known hypervigilance and global hypersensitivity of FM participants.

Comparative effectiveness of various exercise interventions on central sensitisation indices: A systematic review and network meta-analysis

BACKGROUND

Central sensitisation (CS) increases musculoskeletal pain. Quantitative sensory testing (QST) or self-report questionnaires might indicate CS. Indices of CS might be suppressed by exercise, although the optimal exercise regimen remains unclear.

OBJECTIVES

We conducted a systematic review and network meta-analysis (NMA) to investigate effectiveness of different exercise regimens on these CS indices in adults.

METHODS

We searched 6 electronic databases from inception to November 2023. Meta-analysis of randomised controlled trials (RCTs) investigated effects of exercise on all CS indices. Two independent reviewers assessed risk of bias. NMA of RCTs compared CS indices between exercise types. Sensitivity analysis using only high-quality studies was performed to verify the robustness of our results. Certainty was assessed using the GRADE approach.

RESULTS

Of the 249 eligible studies identified, 164 were RCTs, of which 89 provided data suitable for NMA. Meta-analysis revealed large improvement of post-intervention CS indices compared to baseline (SMD -0.81, 95 % CI -0.93 to -0.70). All reported categories of exercise, except stretching exercise alone, were more effective than non-exercise controls. Combined exercises that include stretching together with strengthening exercises (SMD -1.67, 95 % Credible Interval (CrI) -2.41 to -0.97), or strengthening, stretching and aerobic components (SMD -1.61, 95 % CrI -2.74 to -0.56) were most effective at reducing CS indices compared to non-exercise controls. Sensitivity analysis confirmed the robustness of our findings, particularly for combined stretching and strengthening exercise.

CONCLUSIONS

Our meta-analysis suggested that various exercise interventions are effective in improving CS. Multi-component exercise tends to be the most effective, but some exercise combinations might be better than others. Combined exercise featuring strengthening and stretching components, with or without aerobic exercise, shows the greatest likelihood among other combinations of being the optimal exercise type. These findings might have utility informing future trials and personalising treatment strategies for people with CS features.

Classifying Low Back Pain Through Pain Mechanisms: A Scoping Review for Physiotherapy Practice

Background: Low back pain (LBP) is a leading cause of disability worldwide, often driven by distinct pain mechanisms: nociceptive, neuropathic, and central sensitization. Accurate classification of these mechanisms is critical for guiding effective, targeted treatments. Methods: A scoping review was conducted following the Joanna Briggs Institute methodology and reported according to PRISMA-ScR guidelines. A comprehensive literature search was performed in MEDLINE, Cochrane CENTRAL, Scopus, PEDro, and Web of Science. Eligible studies included adults with LBP and focused on clinical criteria for classifying pain mechanisms. Data on study methods, population characteristics, and outcomes were extracted and synthesized. Results: Nine studies met the inclusion criteria. Nociceptive pain was characterized by localized symptoms proportional to mechanical triggers, with no neurological signs. Neuropathic pain was associated with burning sensations, dysaesthesia, and a positive neurodynamic straight leg raise (SLR) test. Central sensitization featured widespread pain, hyperalgesia, and disproportionate symptoms. Tools such as painDETECT, DN4, and the Central Sensitisation Inventory (CSI) were validated for neuropathic and central sensitization pain. Central sensitization and neuropathic pain were linked to greater disability and psychological distress compared to nociceptive pain. Conclusions: This review aims to provide a historical perspective on pain mechanism classifications and to explore how previous frameworks have influenced current diagnostic concepts in physiotherapy practice. By synthesizing key clinical criteria used to differentiate between nociceptive, neuropathic, and central sensitization pain, this review proposes a practical framework to improve the accuracy of pain classification in clinical settings.

A case series of new-onset headache and neurological issues after thoracolumbar spinal cord stimulators

Although spinal cord stimulator (SCS) therapy is generally used safely to treat chronic neuropathic pain conditions, this document highlights the less reported complication of unusual neurological problems including headaches. These developed temporally after the initiation of SCS therapy despite initial positive response to pain. The mechanisms might include activation of trigeminal receptors and neuroplasticity after SCS. We present a series of four cases where patients developed new neurological symptoms like headaches, facial twitching, and tinnitus, that were related to SCS activation. Despite adjustments to the SCS settings and extensive evaluations, these symptoms persisted in all cases, leading to the decision to explant SCS which was otherwise helping pain.

Central sensitization in alcohol use disorder: correlates of pain, addiction and health-related quality of life

BACKGROUND

Central sensitization is an important mechanism underlying many chronic pain conditions. Chronic pain and alcohol use disorder (AUD) are highly comorbid. Despite great scientific interest in brain mechanisms linking chronic pain and AUD, progress has been impeded by difficulty assessing central sensitization in AUD.

OBJECTIVE

The present study is the first to employ a validated surrogate measure to describe central sensitization in a clinical sample with AUD.

METHODS

Participants with AUD (n = 99) were recruited from an academic addiction treatment center. A well-established surrogate measure of central sensitization, The American College of Rheumatology Fibromyalgia Survey Criteria (ACRFMS) was administered. Participants also responded to questions about quality of life (RAND-36), and AUD. Descriptive analyses and Spearman's rho correlations were performed.

RESULTS

Chronic pain and evidence of central sensitization were prevalent. Greater central sensitization was associated with worse health-related quality of life. Participants higher in central sensitization expressed greater endorsement of pain as a reason for AUD onset, maintenance, escalation, treatment delay, and relapse.

CONCLUSION

The present study bolsters prior assertions that AUD and chronic pain might compound one another via progressive sensitization of shared brain circuitry. These results may inform future mechanistic research and precision AUD treatment.

Efficacy and safety evaluation of Boswellia serrata and Curcuma longa extract combination in the management of chronic lower back pain: A randomised, double-blind, placebo-controlled clinical study

BACKGROUND AND AIM

Chronic lower back pain (CLBP) is a major condition that leads to disability and reduced quality of life (QoL). This randomised, double-blind, placebo-controlled clinical study evaluated the efficacy and safety of a novel Boswellia serrata and Curcuma longa combination (CL20192) for the treatment of CLBP.

MATERIAL AND METHODS

Participants with CLBP were randomised to receive either a 300 mg CL20192 capsule (n = 45) or placebo capsule (n = 45) once daily for 90 days. Efficacy was evaluated using the Descriptor Differential Scale and Oswestry Disability Index scores for pain, unpleasantness, and disability. Additionally, the 36-item short form questionnaire was used for QoL evaluation. Frequency of painkiller use, serum levels of inflammatory biomarkers (tumour necrosis factor-α, interleukin-6, and high-sensitivity C-reactive protein), and phytoconstituents (total boswellic acids and curcuminoids) were determined. Therapy satisfaction was assessed using the Physician and Patient Global Assessment Scales.

RESULTS

All randomised participants completed the study. CL20192 supplementation significantly reduced Descriptor Differential Scale pain, unpleasantness, and Oswestry Disability Index scores compared with the placebo group (p < 0.001 for all parameters). Critical QoL scores greatly improved in the CL20192 group. Serum phytoconstituent levels were elevated in the CL20192-treated group. This group demonstrated a significant reduction in inflammatory biomarker levels (tumour necrosis factor-α, interleukin-6, and high-sensitivity C-reactive protein), confirming efficacy in abating CLBP compared with the placebo. Moreover, therapy satisfaction scores were significantly high in the CL20192-treated group, and intervention with CL20192 was well tolerated.

CONCLUSION

Intervention with 300 mg CL20192 capsules, containing a novel combination of Boswellia serrata and Curcuma longa extracts, effectively alleviated pain, unpleasantness, and disability in patients with CLBP compared with the placebo. This outcome was consistent with a decrease in serum inflammatory markers and improved therapy assessment scores.

The role of environmental sensitivity, traumatic experiences, defense mechanisms and mental pain on central sensitivity: testing a path analysis model in chronic headache on quality of life

Central pain sensitivity (CS) is defined as an increased responsiveness of nociceptive neurons in the central nervous system to normal or subthreshold inputs. The main aim of this paper is to investigate if and how specific psychological constructs are related with CS burden in patients with chronic headache (CH). Specifically, research question 1 explores the association of temperament, personality, childhood adversities, defense mechanisms and mental pain with CS burden. Research question 2 aims to test the role of the best predictors of CS burden in affecting the quality of life (QoL) using path analysis. A total of 508 women with CH completed a psycho-diagnostic survey. Results showed that higher levels of low sensory threshold (β = 0.200), bodily threat traumatic experiences (β = 0.156), neurotic defenses (β = 0.109) and mental pain (β = 0.343) emerged as the best predictors of higher CS burden. The model presented demonstrated a satisfactory fit (GFI = 0.984; NFI = 0.966; CFI = 0.979; RMSEA = 0.056 [95% CI 0.028-0.085]) with large and medium effect sizes on physical (-0.654) and psychological QoL (-0.246). The study showed a key role of psychological dimensions in CS burden levels and their relationships with QoL in CH patients. From a clinical perspective, these results suggest the importance of evaluating the level of CS burden during the clinical assessment for chronic pain conditions such as CH, since it may contribute to guide patients to tailored psychological and medical treatments, thereby saving time and costs on diagnostic procedures for chronic pain.

Cross-Cultural Adaptation and Validation of the Central Sensitization Inventory Among Chinese Patients with Chronic Non-Specific Low Back Pain

Purpose

This research aims to develop and validate the Chinese version of the Central Sensitization Inventory (CSI-CV) for patients suffering from chronic non-specific low back pain (CNSLBP). The study evaluates both the validity and reliability of the CSI-CV.

Patients and Methods

The cross-cultural adaptation of the scale strictly adhered to the principles of Bombardier and Beaton. Initially, two professors of Chinese-English translation independently translated the original CSI scale into the target language, and then collaborated with an expert in cross-cultural adaptation to merge into a single version. This version was back-translated into English by two professors whose native language is English. Following this, the scale underwent preliminary review by bilingual experts and the research team, and was preliminarily tested, ultimately culminating in the formation of the CSI-CV version. A total of 310 patients with CNSLBP completed the CSI-CV, while 50 of them repeated the survey one week later to test the stability of the scale. The CSI-CV's reliability, validity, and internal consistency were assessed through exploratory factor analysis (EFA), correlation coefficients, and Cronbach's α.

Results

EFA revealed five distinct factors from the 25 CSI-CV items, covering physical symptoms, emotional distress, fatigue and sleep disturbances, headaches and jaw symptoms, and urinary issues, with a total explained variance of 60.24%. The Cronbach's α was 0.910, and the intraclass correlation coefficient (ICC) was 0.924, indicating strong reliability. Moderate correlations were observed between CSI-CV scores and Five-Level EuroQol Five-Dimensional Questionnaire (r = -0.515), the Brief Pain Inventory (r = 0.586) and Oswestry Disability Index (r = 0.416), demonstrating significant associations with these measures.

Conclusion

The CSI-CV exhibits excellent internal consistency, factor structure, and reliability. Its successful cultural adaptation offers valuable insights for improving treatment approaches for patients with CNSLBP.

The Neurophysiological Impact of Touch-Based Therapy: Insights and Clinical Benefits

The evidence on how touch-based therapy acts on the brain activity opens novel cues for the treatment of chronic pain conditions for which no definitive treatment exists. Touch-based therapies, particularly those involving C-tactile (CT)-optimal touch, have gained increasing attention for their potential in modulating pain perception and improving psychological well-being. While previous studies have focused on the biomechanical effects of manual therapy, recent research has shifted towards understanding the neurophysiological mechanisms underlying these interventions. CT-optimal touch, characterized by gentle stroking that activates CT afferents, may be used to reduce pain perception in chronic pain conditions and to enhance psychological well-being. Further research is needed to fully elucidate the neurophysiological mechanisms involved and to establish the therapeutic efficacy of CT-optimal touch in various clinical populations.

Nociplastic Pain in Endometriosis: A Scoping Review

Endometriosis is an inflammatory chronic condition associated with nociceptive, neuropathic, and nociplastic pain. Central sensitization (CS) is the primary nociplastic pain mechanism. However, there are currently no standardized methods for detecting CS or nociplastic pain. This review aims to identify available tools for characterizing CS/nociplastic pain in endometriosis-related chronic pelvic pain. Following the PRISMA-P protocol, MEDLINE, Embase, Scopus, and PsychINFO databases were searched on 23 April 2024, for the terms "endometriosis", "central sensitization", "nociplastic pain", "widespread pain", and "assessment tools". Publications were selected if they mentioned tool(s) for detecting nociplastic pain or CS in endometriosis patients. Information was extracted on study demographics, assessment types, and the tools used for detection. Of the 379 citations retrieved, 30 papers met the inclusion criteria. When working to identify CS and nociplastic pain, fourteen studies exclusively used patient-reported questionnaires, six used quantitative sensory testing (QST), two used clinical assessments, and eight used multiple approaches combining patient-reported questionnaires and clinical assessment. This review illustrates the diversity of tools currently used to identify CS and nociplastic pain in endometriosis patients. Further research is needed to evaluate their validity and to standardize methods in order to improve the accuracy of nociplastic pain identification and guide treatment.

Central mechanisms of muscle tone regulation: implications for pain and performance

Muscle tone represents a foundational property of the motor system with the potential to impact musculoskeletal pain and motor performance. Muscle tone is involuntary, dynamically adaptive, interconnected across the body, sensitive to postural demands, and distinct from voluntary control. Research has historically focused on pathological tone, peripheral regulation, and contributions from passive tissues, without consideration of the neural regulation of active tone and its consequences, particularly for neurologically healthy individuals. Indeed, simplistic models based on the stretch reflex, which neglect the central regulation of tone, are still perpetuated today. Recent advances regarding tone are dispersed across different literatures, including animal physiology, pain science, motor control, neurology, and child development. This paper brings together diverse areas of research to construct a conceptual model of the neuroscience underlying active muscle tone. It highlights how multiple tonic drive networks tune the excitability of complex spinal feedback circuits in concert with various sources of sensory feedback and in relation to postural demands, gravity, and arousal levels. The paper also reveals how tonic muscle activity and excitability are disrupted in people with musculoskeletal pain and how tone disorders can lead to marked pain and motor impairment. The paper presents evidence that integrative somatic methods address the central regulation of tone and discusses potential mechanisms and implications for tone rehabilitation to improve pain and performance.

Sex Differences in Pain Scores and Medication Consumption for Chronic Non-Cancer Pain

BACKGROUND

Chronic pain is defined as any persistent or recurring pain lasting longer than 3 months that significantly affects a person's quality of life. Millions worldwide are impacted by chronic pain, but its subjective nature makes it difficult to quantify and compare between individuals.

METHODS

This retrospective analysis aimed to examine the differences in pain perception and reporting between male and female patients, as well as how their pain was managed. Data from 1995 patients who met the inclusion criteria were selected from the Advocate Illinois Masonic Pain Clinic database. The types of pain assessed in this study included lower back pain, neck pain, and osteoarthritis.

RESULTS

The findings indicate that females suffer more from chronic pain conditions than males, where lower back pain had the highest prevalence in both sexes (63.7% reported). Baseline Numeric Rating Scale (NRS) scores at the first inpatient visit were statistically higher in females than males (7.95 ± 1.35 vs. 7.72 ± 1.46, p = 0.006). After 1 year of treatment, both sexes reported a clinical improvement in their symptoms. With regards to medication, females reported a higher use of medications such as muscle relaxants, benzodiazepines, and tricyclic antidepressants, while males reported a higher use of opioids (measured in MMEs).

CONCLUSIONS

This study reveals a significant sex difference in the reporting of non-cancer-related chronic pain, with females reporting higher pain intensity than males.

Insomnia and short sleep duration, but not chronotype, is associated with chronic widespread pain: Mendelian randomization study

OBJECTIVES

Sleep disturbance has been associated with chronic widespread pain (CWP), but their causal relationship remains unclear. We aimed to examine the causal relationship and direction between CWP and sleep traits, namely insomnia, sleep duration and chronotype, using Mendelian Randomization.

METHOD

We used genetic association data from ~0.5 million individuals and up to 1.8 million controls from the UK Biobank (UKB). All traits were defined predominantly by self-report. Short sleep duration was defined as average ≤6 hours per 24 hours. Chronotype refers to the inclination to sleep at certain times where some wake and go to bed early ('morning' person), and others wake and go to sleep later ('evening' person). To permit use of the largest available genetic association data, we used the Causal Analysis Using Summary Effect estimates (CAUSE) method, which allows for sample overlap.

RESULTS

Insomnia (OR 1.009, 95% credible interval 1.005, 1.014; p = 0.018 that the causal model is a better fit than non-causal model) and short sleep duration (OR 1.060, 95%CrI 1.038, 1.083; p = 0.040) were causally associated with increased risk of CWP, with limited evidence for reverse causation. There was no evidence in support of long sleep duration or chronotype being associated with CWP.

CONCLUSIONS

This study suggest that insomnia and short sleep duration (≤6 hours) are associated with an increased risk of CWP. Improving short sleep duration and insomnia, rather than chronotype, may be effective in reducing the risk of CWP, although these results should be replicated in epidemiological and interventional studies.

Discordant dry eye disease and chronic pain: A systematic review and meta-analysis

PURPOSE

To evaluate the relative contributions of objective and subjective indicators of dry eye disease (DED) in individuals with chronic pain conditions compared with controls.

METHODS

A systematic review and meta-analysis was conducted of studies that reported the signs and symptoms of DED and/or their prevalence in individuals with chronic pain compared with controls. International Association for the Study of Pain (IASP) International Classification of Diseases (ICD)-11 codes for chronic pain conditions were applied, and outcomes defined as DED signs and symptoms. A search strategy utilised the EMBASE, Web of Science, Cochrane Library and MEDLINE databases. Risk of bias assessment was performed with the Newcastle-Ottawa scale. Random effects meta-analysis calculated mean differences (MD) and odds ratios (OR), while subgroup analysis of different chronic pain conditions explored their relative association with the signs and symptoms of DED. Evidence certainty was evaluated using Grades of Recommendation, Assessment, Development, and Evaluation (GRADE).

RESULTS

Fourteen observational studies comprising 3,281,882 individuals were included. Meta-analysis found high quality evidence that individuals with chronic pain were more likely to experience symptoms of DED than controls (OR = 3.51 [95 %CI: 3.45,3.57]). These symptoms were more severe (MD = 18.53 [95 %CI: 11.90, 25.15]) than controls with a clinically meaningful effect size. Individuals with chronic pain had more rapid tear film disruption (MD = -2.45 [95 %CI: -4.20, -0.70]) and reduced tear production (MD = -5.57 [95 %CI: -9.56, -1.57]) compared with controls (with moderate evidence quality). High quality evidence revealed individuals with chronic pain had lower basal tear production (anaesthetised) than controls (MD = -2.59 [95 %CI: -3.60, -1.58]). Tear film osmolarity showed no significant differences between the chronic pain and pain-free groups. Group differences for DED signs were not considered clinically meaningful.

CONCLUSION

More severe, clinically meaningful symptoms of DED were reported in individuals with chronic pain than controls, however group differences for the signs of DED were typically of limited or questionable clinical relevance. This ocular phenotype where DED is felt more than it is seen in chronic pain may reflect underlying sensory hypersensitivity, shared by both conditions and contributing to their frequent comorbidity. Advancing understanding of this potential pathophysiological mechanism may guide clinical management.

How are sex-gender differences in chair-and-desk-based postural variability explained? A scoping review

BACKGROUND

Desk-work-related musculoskeletal pain is more prevalent among female workers than male workers. This may be contributed to by sex and/or gender differences in postural variability however, the mechanisms underpinning these differences are poorly understood. This review investigates whether desk-based postural variability studies investigate sex-gender differences and, how they explain the mechanisms behind these differences.

METHODS

A scoping review was conducted with four databases (PubMed, Embase, Scopus and ProQuest) searched in June and July 2023. Studies investigating postural variability among desk-based workers were included and a narrative approach used to synthesise results.

RESULTS

15 studies were included. Only four reported on sex-gender differences. None collected psychological or social information to explore reasons for sex-gender differences.

CONCLUSION

The mechanisms behind postural variability differences between sexes and genders are complex and multifactorial. Studies largely do not consider sex and gender and do not collect the information necessary to explain their results.

Yoga, Physical Therapy and Home Exercise Effects on Chronic Low Back Pain: Pain Perception, Function, Stress, and Quality of Life in a Randomized Trial

Low back pain is a common health problem. In this study, we investigated the effects of yoga, physical therapy (PT), and home exercise (HE) on pain perception, function, stress, and quality of life in chronic low back pain (cLBP). We randomly assigned 54 participants to three distinct treatment groups: (a) a physical therapy group (PT) who received spinal stabilization exercises (SSE) combined with local heat and transcutaneous electrical stimulation; (b) a home exercise group (HE) who received SSE as part of the home program; and (c) a yoga group who received yoga exercises. The primary outcome measures were a Visual Analog Scale (VAS) for measuring pain, and the Oswestry Disability Index (ODI) to measure function. Secondary outcome measures were the Tampa Kinesiophobia Scale (TKS), Central Sensitization Inventory (CSI), pain sensitivity (L3 and deltoid R/L PPTs), Spielberger State-Trait Anxiety Inventory (STAI), plasma cortisol and DHEA-S levels, Transversus Abdominis (TrA) muscle activation, and the Nottingham Health Profile (NHP). Assessments were conducted before and after a six-week intervention period. All three groups demonstrated improvements in pain on the VAS, function on the ODI, pain sensitivity on the L3 and deltoid R/L PPTs, CSI, anxiety on the STAI, TrA muscle activation, and quality of life on the NHP (p < .05). The PT group exhibited a more pronounced improvement on the ODI score (p < .05) than the other groups. Cortisol levels only decreased in the PT group (p < .05). The exercises did not impact DHEA-S and NHP-S parameters. Thus, all interventions resulted in decreased stress, pain intensity, pain sensitivity, central sensitization, and improved function and quality of life; there was no singularly superior approach between interventions. These findings will aid in tailoring treatment programs for managing cLBP according to individual needs.

Pathophysiology of Pain and Mechanisms of Neuromodulation: A Narrative Review (A Neuron Project)

Pain serves as a vital innate defense mechanism that can significantly impact an individual's quality of life. Understanding the physiological effects of pain well plays an important role in developing novel pain treatments. Nociceptor neurons play a key role in pain and inflammation. Interactions between nociceptors and the immune system occur both at the site of injury and within the central nervous system. Modulating chemical mediators and nociceptor activity offers promising new approaches to pain management. Essentially, the sensory nervous system is essential for modulating the body's protective response, making it critical to understand these interactions to discover new pain treatment strategies. New innovations in neuromodulation have led to alternatives to opioids individuals with chronic pain with consequent improvement in disease-based treatment and nerve targeting. New neural targets from cellular and structural perspectives have revolutionized the field of neuromodulation. This narrative review aims to elucidate the mechanisms of pain transmission and processing, examine the characteristics and properties of nociceptors, and explore how the immune system influences pain perception. It further provides an updated overview of the physiology of pain and neuromodulatory mechanisms essential for managing acute and chronic pain. We assess the current understanding of different pain types, focusing on key molecules involved in each type and their physiological effects. Additionally, we compare painful and painless neuropathies and discuss the neuroimmune interactions involved in pain manifestation.

About Distress in Chronic Pain Conditions: A Pre-Post Study on the Effectiveness of a Mindfulness-Based Intervention for Fibromyalgia and Low Back Pain Patients

Chronic pain (CP) affects about 30% of the global population and poses significant challenges to individuals and healthcare systems worldwide. The interactions between physiological, psychological, and social factors are crucial in the onset and development of CP conditions. This study aimed to evaluate the effectiveness of mindfulness-based intervention, examining its impact on perceived stress (PSS), depression and anxiety (BDI-II, PGWBI/DEP, SAS, STAI Y), sleep quality (PSQI), and mindfulness abilities (MAAS) in individuals with CP. Participants (N = 89, 84.3% female) underwent one of two diagnoses [fibromyalgia (FM) or low back pain (LBP)] and took part in an MBSR intervention. The mindfulness program proved effective in reducing PSQI scores (F = 11.97; p < 0.01) over time, independently of the type of diagnosis. There was also a marginal increase in trait mindfulness as measured by MAAS (F = 3.25; p = 0.07) in both groups. A significant difference between the two groups was found for the effect on PSS: F (1,87) = 6.46; p < 0.05. Mindfulness practice also reduced anxiety in FM and depressive symptoms in LBP, indicating a reduction in psychological distress among participants. Our findings suggest that mindfulness-based interventions may offer promising avenues for personalized pain management in clinical settings.

Beyond the Hip: Clinical Phenotypes of Hip Osteoarthritis Across the Biopsychosocial Spectrum

Background/Objectives: To identify clinical phenotypes of hip osteoarthritis (OA) within a biopsychosocial framework. Methods: A cross-sectional analysis of 143 individuals with hip OA awaiting total hip arthroplasty (THA) was performed. Phenotyping features included sociodemographic and biomedical information, pain-related cognitions and emotions, mental disorders, traumatic experiences, self-efficacy, social support, perceived stress, and somatosensory function. Outcome measures included the hip disability and osteoarthritis outcome score and the numeric pain-rating scale. Decision tree learning was used to select the most important phenotyping features. K-means clustering analyses were performed to identify clinical phenotypes and a decision tree algorithm was trained to classify individuals in the identified clinical phenotypes. Results: Selected phenotyping features associated with pain and disability included a combination of biomedical, psychological, and social variables. Two distinct clinical phenotypes were identified. Individuals within the maladaptive phenotype (34%) reported more comorbidities, less self-efficacy and higher levels of anxiety, depression, pain-related fear-avoidance, and feelings of injustice. No differences were found regarding social support and somatosensory function. Regarding the outcome measures, individuals within the maladaptive phenotype reported higher levels of pain and disability. Finally, based on the Fear-Avoidance Components Scale (FACS) and the anxiety subscale of the Hospital Anxiety and Depression Scale (HADS-A), individuals could be classified into the clinical phenotypes with 87.8% accuracy. Conclusions: Two clinical phenotypes, an adaptive and a maladaptive phenotype, can be identified in individuals with hip OA using the FACS and HADS-A. The identification of these clinical phenotypes represents a crucial step toward precision medicine, enabling the development of targeted treatment pathways tailored to the distinct biomedical and psychological features of each phenotype.

Pain Neuroscience Education: Teaching People About Pain

Chronic pain is an ever-increasing global challenge, and few strategies have been shown to significantly alter this trajectory, and a pure pharmaceutical approach, especially opioids, is not the answer. To truly impact a person with chronic pain's life, current best-evidence supports changing their cognitions (how they think about their pain), moving more, and calming the peripheral and central nervous system, including non-pharmacological strategies. All healthcare providers, however, must use a unified strategy regardless of their professional designation, skillset, and clinical setting. One variable that spans all patient interactions is communication. All healthcare providers talk to patients, be it during informal, casual conversation or during specific medical education tied to diagnosis, prognosis, treatment, reassurance, and more. Current evidence supports teaching patients more about their pain experience, called pain neuroscience education (PNE), which has significant clinical benefits. Any provider may offer PNE, from physicians, pharmacists, therapists, psychologists, nurses, etc. Pain neuroscience education is shown to positively influence self-reported pain, disability, fear-avoidance, pain catastrophizing, movement, and healthcare utilization in patients with chronic pain. This commentary aims to introduce all healthcare providers to PNE, and how, along with non-pharmacological treatments (PNE+) have the ability to positively impact people's lives living with chronic pain.

Sensitization-associated and neuropathic-associated symptoms in patients with unilateral lateral elbow tendinopathy: an exploratory study

OBJECTIVES

We evaluate the presence of sensitization-associated symptoms and neuropathic pain features and identify if there is an association between these symptoms and pressure pain sensitivity, pain, and related-disability in lateral elbow tendinopathy.

METHODS

Thirty-seven (43% women, age: 45.5 ± 9.5 years) patients with lateral elbow tendinopathy completed: demographic (i.e. age, height, and weight); clinical (i.e. pain history, pain intensity, and Disabilities of the Arm, Shoulder and Hand); and psychophysical (i.e. pressure pain thresholds at the elbow, cervical spine, hand, and leg) outcomes, and the Central Sensitization Inventory and Self-administered Leeds Assessment of Neuropathic Symptoms and Signs questionnaires. Step-wise multiple linear regression models were performed to identify predictors of sensitization- or neuropathic-associated symptoms.

RESULTS

Six (16%) patients exhibited sensitization-associated symptoms (mean: 46.5, SD: 6.1), whereas 13 (35%) patients showed neuropathic-associated symptoms (mean: 13.5; SD: 1.4). Sensitization-associated symptoms were positively associated with neuropathic-associated symptoms (r = 0.538, P = .001) and negatively associated with pressure pain thresholds at the leg (r = -0.378, P = .021). Neuropathic-associated symptoms were positively associated with related-disability (r = 0.479, P = .003) and negatively associated with pressure pain threshold at the elbow (r = -0.394, P = .017). Stepwise regression analyses revealed that neuropathic-like symptoms explained 26.8% of the variance of sensitization symptoms (r2: 0.268), whereas pressure pain threshold at the elbow explained an additional 6.6% to neuropathic-like symptoms (r2: 0.334).

CONCLUSION

This explorative study identified sensitization- and neuropathic-associated symptoms in 16% and 35% of the people with lateral elbow tendinopathy. Sensitization- and neuropathic-associated symptoms were associated. Pressure pain sensitivity at the elbow (peripheral sensitization) was associated with neuropathic -associated symptoms.

An interdisciplinary perspective on peripheral drivers of pain in rheumatoid arthritis

Pain is one of the most debilitating symptoms of rheumatoid arthritis (RA), and yet remains poorly understood, especially when pain occurs in the absence of synovitis. Without active inflammation, experts most often attribute joint pain to central nervous system dysfunction. However, advances in the past 5 years in both immunology and neuroscience research suggest that chronic pain in RA is also driven by a variety of abnormal interactions between peripheral neurons and mediators produced by resident cells in the local joint environment. In this Review, we discuss these novel insights from an interdisciplinary neuro-immune perspective. We outline a potential working model for the peripheral drivers of pain in RA, which includes autoantibodies, resident immune and mesenchymal cells and their interactions with different subtypes of peripheral sensory neurons. We also offer suggestions for how future collaborative research could be designed to accelerate analgesic drug development.

Assessment of small fiber neuropathy and distal sensory neuropathy in female patients with fibromyalgia

BACKGROUND/AIMS

We investigated sudomotor dysfunction, small fiber neuropathy (SFN), and their clinical significance in female fibromyalgia patients.

METHODS

Fibromyalgia patients and healthy controls (HCs) were recruited. Clinical and laboratory data were measured. Electrochemical skin conductance (ESC) values of hands and feet were assessed by SUDOSCAN. Additionally, several other methods were employed, including nerve conduction study (NCS), electromyography (EMG), and questionnaires. Spearman correlation coefficient was calculated to identify factors associated with ESC values of SUDOSCAN.

RESULTS

Twenty-two female fibromyalgia patients and 22 female HCs were recruited. The fibromyalgia group had lower EQ5D and higher Toronto Clinical Neuropathy scores than the HC group. Most of the EMG/NCS findings of motor and proximal sensory nerves were comparable between the fibromyalgia and HC groups, whereas sensory nerve action potential amplitudes of distal sensory nerves were significantly lower in the fibromyalgia group. Mean ESC values of hands and feet were significantly lower in the fibromyalgia group than in the HC group (57.6 ± 16.2 vs. 68.8 ± 10.3 μS, p = 0.010 for hands, 64.9 ± 11.5 vs. 72.0 ± 8.2 μS, p = 0.025 for feet, respectively). Moderate to severe SFN was more common in the fibromyalgia group (68.2%) than in the HC group (68.2 vs. 50%, p = 0.019). Fibromyalgia disease duration was significantly correlated with the ESC values of hands/feet, and tricyclic antidepressant (TCA) responders had higher ESC values than non-responders.

CONCLUSION

SFN was commonly detected in fibromyalgia patients who had normal EMG/NCS findings and was more severe in fibromyalgia patients with longer disease duration. SUDOSCAN may predict response to TCA therapy.

The Photo- and Phonosensitivity Avoidance Behavior Scales: Evaluating Clinical Utility in Pediatric Primary Chronic Headache

Background/Objectives: Pediatric primary chronic headache disorders are often associated with sensitivities to light (photosensitivity) and sound (phonosensitivity) that may trigger or worsen headache pain. These sensory sensitivities may result in changes to activity participation or environmental modifications to avoid visual and auditory stimuli. Over time, avoidance behaviors can inadvertently increase functional disability, suggesting the importance of their thorough consideration. The PhotoSensitivity and PhonoSensitivity Avoidance Behavior Scales (PHOTO-SABS and PHONO-SABS, respectively) were recently developed and preliminarily validated to assist clinicians in evaluating such behaviors. This study aimed to confirm each of their factor structures in a new sample and enhance their clinical utility. Methods: A sample of 176 youth (aged 8-17) with a primary chronic headache diagnosis completed the PHOTO-SABS and PHONO-SABS as part of their multidisciplinary evaluation in a pediatric headache clinic. Results: Consistent with the previous validation, confirmatory factor analyses supported a two-factor model for the PHOTO-SABS and a single-factor model for the PHONO-SABS. Tertile groupings (low, moderate, high) provided the most appropriate clinical reference points. The relative change criterion (RCCrit) was established at 6.4 points for both measures. Conclusions: These findings confirm that the PHOTO- and PHONO-SABS are psychometrically robust tools for clinicians to evaluate sensitivity-related avoidance behavior and to monitor response to interventions in youth with primary chronic headaches.

Value of the central sensitisation inventory in patients with axial spondyloarthritis

BACKGROUND

In many patients with axial spondyloarthritis (axSpA), pain persists despite anti-inflammatory medication. Quantitative sensory testing (QST) indirectly assesses altered somatosensory function, though its clinical practicality is limited. The Central Sensitisation Inventory (CSI) could be an alternative in the initial assessment of central sensitisation (CS). This study aimed to investigate the value of the CSI in evaluating CS in patients with axSpA by (1) assessing somatosensory function related to CS with QST and (2) exploring associations between CSI, QST, patient and disease characteristics and pain-related psychosocial factors.

METHODS

Consecutive outpatients from the Groningen Leeuwarden AxSpA cohort underwent QST, including pressure pain threshold (PPT), temporal summation (TS) and conditioned pain modulation (CPM). Participants completed questionnaires assessing CS (CSI), illness perception (Revised Illness Perception Questionnaire, IPQ-R), pain-related worrying (Pain Catastrophising Scale, PCS), fatigue (Modified Fatigue Impact Scale, MFIS), anxiety/depression (Hospital Anxiety and Depression Scale, HADS) and coping. QST measurements were stratified for CSI≥40.

RESULTS

201 patients with axSpA were included; 63% male, 64% radiographic axSpA, median symptom duration 12 years (IQR 5-24), mean Axial Spondyloarthritis Disease Activity Score 2.1±1.0. Patients with CSI≥40 had significantly lower PPTs and higher TS than CSI<40 (p<0.004). No significant differences in CPM were observed. In multivariable linear regression, sex, PCS, IPQ-R Identity, MFIS and HADS anxiety were independently associated with CSI (78% explained variance).

CONCLUSION

In this large cross-sectional study in patients with axSpA, the CSI appears as a useful initial CS assessment questionnaire. When CSI scores indicate CS, considering pain-related psychosocial factors is important. These results emphasise the need for a biopsychosocial approach to manage chronic pain in patients with axSpA.