Central sensitization, chronic pain, and other symptoms: Better understanding, better management

Microbial Symphony: Exploring the Role of the Gut in Osteoarthritis-Related Pain. A Narrative Review

One of the most common musculoskeletal disorders, osteoarthritis (OA), causes worldwide disability, morbidity, and poor quality of life by degenerating articular cartilage, modifying subchondral bone, and inflaming synovial membranes. OA pathogenesis pathways must be understood to generate new preventative and disease-modifying therapies. In recent years, it has been acknowledged that gut microbiota (GM) can significantly contribute to the development of OA. Dysbiosis of GM can disrupt the "symphony" between the host and the GM, leading to a host immunological response that activates the "gut-joint" axis, ultimately worsening OA. This narrative review summarizes research supporting the "gut-joint axis" hypothesis, focusing on the interactions between GM and the immune system in its two main components, innate and adaptive immunity. Furthermore, the pathophysiological sequence of events that link GM imbalance to OA and OA-related pain is broken down and further investigated. We also suggest that diet and prebiotics, probiotics, nutraceuticals, exercise, and fecal microbiota transplantation could improve OA management and represent a new potential therapeutic tool in the light of the scarce panorama of disease-modifying osteoarthritis drugs (DMOADs). Future research is needed to elucidate these complex interactions, prioritizing how a particular change in GM, i.e., a rise or a drop of a specific bacterial strain, correlates with a certain OA subset to pinpoint the associated signaling pathway that leads to OA.

Chronic pain in pediatric patients: epidemiology, pathophysiology, and mitigation strategies

PURPOSE OF REVIEW

To provide an updated summary on the epidemiology, pathophysiology, and treatment strategies of chronic pain in pediatric patients and its differences with chronic pain in adults.

RECENT FINDINGS

Chronic pain in children is common, can be debilitating and can progress into adulthood, thus it requires an interdisciplinary evaluation and management. Targeting interdisciplinary care, including psychology, physical, and/or occupational therapy, has been shown to improve pain and function. Recent decline in mental health post pandemic has correlated with increase in pediatric chronic pain thus the need to identify patients at risk and offer early interdisciplinary treatment.

SUMMARY

Chronic pediatric pain should be addressed under the biopsychosocial model, where the biological, psychological, and social factors are evaluated on how they influence the pain perception, pain experience, functional ability, and treatment focus. Pain education to patients and their families is the crucial initial step towards a functional rehabilitation of pain.

Central sensitization: its prevalence and impact on quality of life among hemodialyzed patients

BACKGROUND/AIM

Data on the role of central sensitization in hemodialyzed patients are scarce. The aim was to identify the impact of central sensitization on quality of life and elucidate the risk factors for the development of central sensitization in patients receiving hemodialysis.

METHODS

Central sensitization, quality of life, psychological well-being, and sleep were assessed by the Central Sensitization Inventory (CSI), abbreviated version of the World Health Organization Quality of Life Instrument (WHOQOL-BREF), Hospital Anxiety and Depression Scale (HADS), and Jenkins Sleep Evaluation Scale (JSS), respectively. The effect of central sensitization on quality of life and the predictors of the development of central sensitization were assessed by regression analyses.

RESULTS

The frequency of central sensitization was 48% in the study population (n = 100). Patients with central sensitization had significantly higher pain intensity, worse sleep quality, and more impaired psychological status (p < 0.05 for all). The CSI score negatively affected all quality of life domains on its own (p < 0.001 for all, adjusted R2 ranged from 0.17 to 0.47). Dialysis vintage (OR, 0.8; 95% CI, 0.7 to 1.0), pain (OR, 1.5; 95% CI, 1.1 to 2.0), JSS (OR, 1.3; 95% CI, 1.1 to 1.5), and HADS-total (OR, 1.1; 95% CI, 1.0 to 1.2) were determined as the independent risk factors for central sensitization (p < 0.05 for all).

CONCLUSION

This study confirms that given the high frequency of central sensitization and its significant negative impact on quality of life, the presence of central sensitization should be investigated in patients undergoing hemodialysis.

Central sensitization significantly deteriorates functionality and the interpretation of self-reported disease activity in primary Sjögren's syndrome

BACKGROUND

Central sensitization has a major role in health-related parameters in musculoskeletal conditions. There is still a lack of understanding regarding the impact of central sensitization on the interpretation of disease activity and functional disability in primary Sjögren's syndrome (pSS).

METHODS

The Central Sensitization Inventory (CSI) was used to screen for central sensitization. Disease-related parameters, including objective tests, medication use, the EULAR SS Patient Reported Index (ESSPRI), and the EULAR SS Disease Activity Index (ESSDAI), were assessed. Functionality, quality of life, sleep, and mental health were evaluated by the Health Assessment Questionnaire-Disability Index (HAQ-DI), Medical Outcomes Study 36-Item Short Form Health Survey (SF-36), Jenkins Sleep Evaluation Scale (JSS), and Hospital Anxiety and Depression Scale (HADS), respectively. The effect of central sensitization on functionality and disease activity measures was assessed by regression analyses.

RESULTS

The frequency of central sensitization was 65% in patients with pSS (n = 60). Patients with central sensitization had higher HAQ-DI, ESSPRI, HADS, and JSS and lower SF-36 subdomain scores (p < 0.05 for all). A significant positive correlation was observed between the CSI score and the ESSPRI, JSS, HAQ-DI, and HADS scores (Spearman's rho ranging from 0.342 to 0.739). The multiple regression analysis indicated that CSI was independently associated with HAQ-DI (adjusted R2 = 0.19, B = 0.01) and ESSPRI (adjusted R2 = 0.45, B = 0.08) (p < 0.001 for all).

CONCLUSION

This study confirms that central sensitization has a major impact on functionality and the interpretation of self-reported disease activity in pSS. When devising strategies for the management of patients with pSS, it is crucial to consider these close relationships. Key Points • The frequency of central sensitization accompanying primary Sjögren's syndrome is considerable. • Central sensitization was independently associated with functionality and self-reported disease activity assessment. • This close association leads to challenges in functionality, evaluating treatment response, and planning or switching between therapies in primary Sjögren's syndrome.

In-Person or Virtual Educational Preferences in Patients With Fibromyalgia: A Cross-Sectional Survey Study at an Academic Medical Center

PURPOSE

Patient education is a core component of treating fibromyalgia and central sensitization disorders. We sought to evaluate whether patients with fibromyalgia prefer virtual or in-person educational classes as part of their treatment program, identify underlying factors with their educational modality choice, and highlight benefits or barriers associated with in-person or online educational sessions.

DESIGN

A cross-sectional survey with a qualitative feedback component was utilized.

METHODS

A voluntary, anonymous survey was distributed to all participants (in-person and virtual) of the fibromyalgia and chronic fatigue clinic treatment program from October 2021 through March 2022.

RESULTS

In total 90 participants completed the survey. Nearly all (94%) agreed that the pathophysiologic education was relevant and valuable and (98%) agreed to feeling confident with implementing management strategies. Perceived connection between the participants varied between groups (85% of in-person vs 48% of online; p < .001), as did perceived engagement (100% of in-person vs 71% of online; p = .001).

CONCLUSIONS

Patients value education and find it useful in treating fibromyalgia, regardless of the educational modality. The online group reported more limitations including less engagement, class participation, and connection with peers.

CLINICAL IMPLICATIONS

As virtual education platforms become more widely available and may be easier to access than in-person options, it is important to understand patient preferences, benefits, and disadvantages of educational modalities to ensure education and patient outcomes remain equitable.

Conservative Management of Acute Sports-Related Concussions: A Narrative Review

This review explores the application of the conservative management model for pain to sports-related concussions (SRCs), framing concussions as a distinct form of pain syndrome with a pathophysiological foundation in central sensitization. Drawing parallels with proven pain management models, we underscore the significance of a proactive approach to concussion management. Recognizing concussions as a pain syndrome allows for the tailoring of interventions in alignment with conservative principles. This review first covers the epidemiology and controversies surrounding prolonged concussion recovery and persistent post-concussion symptoms (PPCS). Next, the pathophysiology of concussions is presented within the central sensitization framework, emphasizing the need for early intervention to mitigate the neuroplastic changes that lead to heightened pain sensitivity. Five components of the central sensitization process specific to concussion injuries are highlighted as targets for conservative interventions in the acute period: peripheral sensitization, cerebral metabolic dysfunction, neuroinflammation, glymphatic system dysfunction, and pain catastrophizing. These proactive interventions are emphasized as pivotal in accelerating concussion recovery and reducing the risk of prolonged symptoms and PPCS, in line with the philosophy of conservative management.

Can a specific biobehavioral-based therapeutic education program lead to changes in pain perception and brain plasticity biomarkers in chronic pain patients? A study protocol for a randomized clinical trial

BACKGROUND

Chronic pain conditions are complex multifactorial disorders with physical, psychological, and environmental factors contributing to their onset and persistence. Among these conditions, the role of brain-derived neurotrophic factor (BDNF) and the impact of a specific therapeutic education (TE) on pain management have emerged as important areas of research.

OBJECTIVE

This study aims to investigate the effects of a specific type of therapeutic education on pain levels and BDNF concentrations.

METHODS

In this single-blind, randomized clinical trial, patients will be randomly assigned to one of two groups: one will receive exercise with TE and the other without TE. Assessments will be made at baseline, mid-treatment, post-intervention, and at one and eight months.

OUTCOMES

This study will shed light on the effectiveness of a therapeutic education (TE) program in pain management. Additionally, it will provide information on its effects on BDNF levels, a biomarker of brain plasticity, as well as on various psychosocial variables that can influence pain experience.

CONCLUSION

By comprehensively addressing the need to quantify brain changes more precisely in individuals with chronic pain during interventions like TE and recognizing the importance of establishing a more structured and comprehensive protocol, this study lays a solid and replicable foundation for future evidence-based treatment developments.

Development, Insults and Predisposing Factors of the Brain's Predictive Coding System to Chronic Perceptual Disorders-A Life-Course Examination

The predictive coding theory is currently widely accepted as the theoretical basis of perception and chronic perceptual disorders are explained as the maladaptive compensation of the brain to a prediction error. Although this gives us a general framework to work with, it is still not clear who may be more susceptible and/or vulnerable to aberrations in this system. In this paper, we study changes in predictive coding through the lens of tinnitus and pain. We take a step back to understand how the predictive coding system develops from infancy, what are the different neural and bio markers that characterise this system in the acute, transition and chronic phases and what may be the factors that pose a risk to the aberration of this system. Through this paper, we aim to identify people who may be at a higher risk of developing chronic perceptual disorders as a reflection of aberrant predictive coding, thereby giving future studies more facets to incorporate in their investigation of early markers of tinnitus, pain and other disorders of predictive coding. We therefore view this paper to encourage the thinking behind the development of preclinical biomarkers to maladaptive predictive coding.

The effects of alpha-pinene on inflammatory responses and oxidative stress in the formalin test

Alpha-pinene (α- pinene), an essential oil that falls under the category of monoterpenes, has various advantages. This research delves into the potential benefits of α-pinene in alleviating nociception caused by the formalin test and the molecular mechanisms involved. Alpha-pinene (1, 5, or 10 mg/kg/day, i.p.) was administrated for 7 days before the formalin test. Observations of nociceptive behaviors were made during the formalin test. We examined the levels of TNF-α and IL-1β, as well as the expression of COX-1 in the spinal cord. Additionally, we evaluated the levels of TNF-α, IL-1β, SOD, GSH, CAT, and MDA in the skin of the hind paw that received a formalin injection. The peripheral injection of formalin triggered nociceptive behaviors, which was notably diminished by α-pinene 5 or 10 mg/kg. The biochemical evaluation revealed that α-pinene significantly moderated the evaluation in TNF-α and IL-1β in the spinal cord induced by formalin injection. Additionally, it was found that α-pinene had a decreasing effect on the expression of COX-1 protein in the spinal cord. Also, α-pinene 5 or 10 mg/kg caused a decrease of TNF-α, IL-1β, and MDA and an increase of SOD, GSH, and CAT at the formalin injection site. The study discovered that doses of 5 or 10 mg/ml of α-pinene can effectively relieve nociceptive response in the formalin test. Alpha-pinene pretreatment reduced the presence of pro-inflammatory cytokines. It also improved the oxidative stress condition by enhancing antioxidant factors and reducing oxidant factors.

Effect of virtual reality combined with repetitive transcranial magnetic stimulation on musculoskeletal pain and motor development in children with spastic cerebral palsy: a protocol for a randomized controlled clinical trial

PURPOSE

This trial aims to investigate the efficacy and safety of virtual reality (VR) combined with repetitive transcranial magnetic stimulation (rTMS) for improving musculoskeletal pain and motor development in children with unilateral spastic cerebral palsy (CP).

METHODS

This study protocol is for a randomized controlled trial consisting of 2 treatment sessions (3 days/week for 4 weeks in each session, with a 1-week interval between sessions). We will recruit children aged 3-10 years with unilateral spastic CP (Gross Motor Function Classification System level I or II). Participants will be randomly divided into 3 groups: the VR + rTMS group (immersive VR intervention, rTMS and routine rehabilitation therapy), rTMS group (rTMS and routine rehabilitation therapy), and control group (sham rTMS and routine rehabilitation therapy). VR therapy will involve a daily 40-minute movement training session in a fully immersive environment. rTMS will be applied at 1 Hz over the primary motor cortex for 20 min on the contralateral side. The stimulation intensity will be set at 90% of the resting motor threshold, with 1200 pulses applied. A daily 60-minute routine rehabilitation therapy session including motor training and training in activities of daily living will be administered to all participants. The primary outcome will be pain intensity, assessed by the Revised Face, Legs, Activity, Cry, and Consolability Scale (R-FLACC). The secondary outcomes will include motor development, evaluated by the 66-item version of the Gross Motor Function Measure (GMFM-66) and Fine Motor Function Measure (FMFM); balance capacity, measured by the interactive balance system; activities of daily living; and quality of life, measured by the Barthel index and the Chinese version of the Cerebral Palsy Quality of Life scale for Children (C-CP QOL-Child). Safety will be monitored, and adverse events will be recorded during and after treatment.

DISCUSSION

Combined application of VR therapy and rTMS may reveal additive effects on pain management and motor development in children with spastic CP, but further high-quality research is needed. The results of this trial may indicate whether VR therapy combined with rTMS achieves a better analgesic effect and improves the motor development of children with spastic CP.

TRIAL REGISTRATION

Registration number: ChiCTR230069853. Trial registration date: 28 March 2023. Prospectively registered.

Negative correlation between central sensitization and forgotten joint score-12 after total hip arthroplasty

BACKGROUND

Central sensitization is a condition in which even mild stimuli cause pain due to increased neuronal reactivity in the dorsal horn of the spinal cord. It is one of factors of chronic pain in patients with osteoarthritis. However, it is unknown whether central sensitization relates to clinical outcomes after total hip arthroplasty (THA). This study aimed to clarify whether preoperative central sensitization relates to the forgotten joint score-12 (FJS) after THA. Moreover, the secondary outcome was to identify which items in the FJS were most related by central sensitization.

METHODS

This retrospective analysis included 263 hips (263 patients; 51 males and 212 females) that underwent primary THA in our institute and were available for evaluation one year postoperatively. The average patient age was 64.8 ± 11.9 years. The Central Sensitization Inventory (CSI) part A, which is a patient-reported outcome, was used to measure preoperative central sensitization. The correlation between preoperative CSI and postoperative FJS and the association between postoperative FJS and preoperative CSI severity were determined. Moreover, difference in each FJS item was evaluated by CSI severity.

RESULTS

Twenty-six patients (9.9%) had central sensitization preoperatively. Preoperative CSI scores and postoperative FJS were negatively correlated (r =  - 0.331, p < 0.0001). The postoperative FJS was significantly lower in patients with moderate or higher preoperative CSI severity than that in patients with subclinical or mild preoperative CSI severity (p < 0.05). FJS items with movement of daily life were significantly worse in the moderate or higher CSI severity compared with subclinical group (p < 0.05 or p < 0.01).

CONCLUSION

Central sensitization prior to THA negatively related to postoperative FJS. In particular, the relationship of central sensitization was found to be significant in FJS items with movement, which would lead to lower patient satisfaction after THA. To get better postoperative outcomes in patients with preoperative central sensitization, improving central sensitization would be important.

Advancing the Assessment and Treatment of Comorbid Pediatric Chronic Functional Abdominal Pain (CFAP) and Restrictive Eating Disorders

The aim of this review is to heighten awareness of the association between chronic functional abdominal pain (CFAP) and restrictive eating disorders (ED) in adolescents. We describe current diagnostic practices and propose future research efforts to improve the assessment and treatment of comorbid CFAP and restrictive EDs. A narrative review of the literature on CFAP and EDs was performed using PubMed, JSTOR, ScienceDirect, and PsycINFO and the following search terms: 'restrictive eating disorders', 'chronic functional abdominal pain', 'chronic pain' 'treatment' 'diagnosis' and 'adolescents'. Published studies on restrictive EDs and CFAP from May 2008 to March 2023 were included. Ascribable to the overlap in etiology and symptom presentation, adolescents with chronic pain are significantly less likely to have their ED pathology promptly identified by providers compared to adolescents without comorbid chronic pain. This highlights the importance of the time sensitive and accurate identification of EDs in adolescents with CFAP. Overall, assessment methods are limited and EDs take longer to be identified in adolescents with comorbid CFAP. Future efforts should address diagnostic practices in pediatric settings and improve the communication among medical and mental health providers in order to promote the rapid and effective diagnosis and treatment of comorbid CFAP and EDs.

Alleviation of Pain, PAIN Interference, and Oxidative Stress by a Novel Combination of Hemp Oil, Calamari Oil, and Broccoli: A Randomized, Double-Blind, Placebo-Controlled Trial

Chronic pain is a critical health issue in the US that is routinely managed pharmacologically with diminishing results. The widespread misuse and abuse of prescription opioid pain medications have caused both healthcare providers and patients to seek alternative therapeutic options. Several dietary ingredients have been traditionally used for pain relief and are known to have potential analgesic properties. This double-blind, placebo-controlled randomized clinical trial aimed to test whether a novel combination of full spectrum hemp oil (phytocannabinoids), calamari oil (omega-3 fatty acids), and broccoli (glucosinolates) could reduce chronic pain and attenuate damage from oxidative stress in adults seeking chiropractic care. Participants (average age = 54.8 ± 13.6 years old) were randomly assigned to consume a whole-food, multi-ingredient supplement (n = 12, intervention and standard chiropractic care) or placebo (n = 13, mineral oil and standard chiropractic care) daily for 12 weeks. The subjects' self-reported perceived pain, pain interference, and reactive oxygen species (ROS) status in the peripheral blood mononuclear cells (PBMC) were quantified at baseline, mid-checkpoint, and postintervention. The intervention was positively associated with a 52% decrease in pain intensity and several parameters of pain interference, including quality of sleep. Decreases in the markers of oxidative stress were also observed in the participants from the intervention group (29.4% decrease in PMBC ROS). Our findings indicated that supplementation with a novel combination of hemp oil, calamari oil, and broccoli has the potential to manage chronic pain when combined with standard chiropractic care, as suggested by its effects on pain intensity and oxidative stress.