Sex differences and mechanisms of muscle pain

Associations of Gender Role and Pain in Musculoskeletal Disorders: A Mixed-Methods Systematic Review

Previous studies have investigated the association of gender roles with pain outcomes in healthy individuals. However, little is known about this association in those with musculoskeletal (MSK) disorders. Therefore, this mixed-methods systematic review aimed to investigate the association of sociocultural gender roles on pain outcomes in adults with MSK disorders. Literature from Medline, CINAHL, Web of Science, and Embase was reviewed from inception to February 2023. Eligibility criteria included studies of adults with an MSK pain disorder that explored the relationship between gender roles and pain for all primary qualitative and quantitative study designs. Exclusion criteria were gray literature, review articles, case studies, and conference proceedings. Risk of bias was assessed via the Quality Appraisal for Diverse Studies for quantitative studies and the McMaster Quality Appraisal Tool for qualitative studies. Eleven studies were included, 9 qualitative, and 2 quantitative with a total of 540 participants (19.6% women, 80.4% men) with various MSK disorders. The convergent integrated approach was used to synthesize data from the qualitative and quantitative studies resulting in 3 themes and 7 subthemes. Our findings identified differences in the way individuals explained the cause of their pain, were treated for their pain in a social and systemic context, and in describing the effect pain had on their lives based on gender roles. There is a need for pain management to evolve to acknowledge the individual pain experience through exploration of an individual's gender identity and roles. PERSPECTIVE: This article demonstrates that gender roles have a multidimensional influence on the pain experience in those with MSK disorders. These findings support the development of gender-sensitive, patient-centered approaches to pain management, acknowledging each individual's important roles and identities.

Motor Point as an Alternative to Femoral Nerve Stimulation for the Assessment of Quadriceps Muscle Inhibition in Healthy Women

CONTEXT

The evaluation of quadriceps muscle inhibition with the interpolated twitch technique is usually performed by stimulating the femoral nerve (FN). However, there are some problems related to the use of this stimulation site, which may be partially overcome by delivering the stimulation over the motor point (MP). This study sought to compare MP to FN stimulation at different joint angles for the evaluation of quadriceps muscle inhibition, resting peak torque, and discomfort in healthy women.

DESIGN

Cross-sectional study.

METHODS

Sixteen healthy women (age: 28 [4] y; body mass: 60 [5] kg; height: 162 [5] cm) participated in this study. Supramaximal paired stimuli were delivered to the FN and to the rectus femoris MP before and during maximal voluntary contractions at different knee angles (15°, 30°, 45°, 60°, and 90° of knee flexion) to assess muscle inhibition and resting peak torque. Discomfort was also recorded for each stimulation site and knee angle.

RESULTS

Muscle inhibition was similar between the 2 stimulation sites (P > .05) and was higher at 45° than at 90° (P = .03). MP stimulation evoked lower resting peak torque at 30° (P = .004), 60° (P = .006), and 90° (P = .006) and higher discomfort at 30° (P = .008) and 90° (P = .027) compared to FN stimulation.

CONCLUSIONS

Despite lower resting peak torque and higher discomfort at some angles, MP stimulation provided similar muscle inhibition to FN stimulation at all knee angles and is therefore a valid method to evaluate quadriceps muscle inhibition in healthy women. MP stimulation can be used as an alternative to FN stimulation for the evaluation of quadriceps muscle inhibition with no added discomfort at the angles where muscle inhibition is the highest.

A calculator for musculoskeletal injuries prediction in surgeons: a machine learning approach

BACKGROUND

Surgical specialists experience significant musculoskeletal strain as a consequence of their profession, a domain within the healthcare system often recognized for the pronounced impact of such issues. The aim of this study is to calculate the risk of presenting musculoskeletal injuries in surgeons after surgical practice.

METHODS

Cross-sectional study carried out using an online form (12/2021-03/2022) aimed at members of the Spanish Association of Surgeons. Demographic variables on physical and professional activity were recorded, as well as musculoskeletal pain (MSP) associated with surgical activity. Univariate and multivariate analysis were conducted to identify risk factors associated with the development of MSP based on personalized surgical activity. To achieve this, a risk algorithm was computed and an online machine learning calculator was created to predict them. Physiotherapeutic recommendations were generated to address and alleviate each MSP.

RESULTS

A total of 651 surgeons (112 trainees, 539 specialists). 90.6% reported MSP related to surgical practice, 60% needed any therapeutic measure and 11.7% required a medical leave. In the long term, MSP was most common in the cervical and lumbar regions (52.4, 58.5%, respectively). Statistically significant risk factors (OR CI 95%) were for trunk pain, long interventions without breaks (3.02, 1.65-5.54). Obesity, indicated by BMI, to lumbar pain (4.36, 1.84-12.1), while an inappropriate laparoscopic screen location was associated with cervical and trunk pain (1.95, 1.28-2.98 and 2.16, 1.37-3.44, respectively). A predictive model and an online calculator were developed to assess MSP risk. Furthermore, a need for enhanced ergonomics training was identified by 89.6% of surgeons.

CONCLUSIONS

The prevalence of MSP among surgeons is a prevalent but often overlooked health concern. Implementing a risk calculator could enable tailored prevention strategies, addressing modifiable factors like ergonomics.

Sex-specific role of RNA-binding protein, pAUF1, on prolonged hypersensitivity after repetitive ischemia with reperfusion injury

ABSTRACT

Repetitive ischemia with reperfusion (I/R) injury is a common cause of myalgia. Ischemia with reperfusion injuries occur in many conditions that differentially affect males and females including complex regional pain syndrome and fibromyalgia. Our preclinical studies have indicated that primary afferent sensitization and behavioral hypersensitivity caused by I/R injury may be due to sex-specific gene expression in the dorsal root ganglia (DRG) and distinct upregulation of growth factors and cytokines in the affected muscles. To determine how these unique gene expression programs may be established in a sex-dependent manner in a model that more closely mimics clinical scenarios, we used a developed prolonged ischemic myalgia model in mice whereby animals experience repeated I/R injuries and compared behavioral results with unbiased and targeted screening strategies in male and female DRG. Several distinct proteins were found to be differentially expressed in male and female DRG, including phosphorylated AU-rich element RNA-binding protein (pAUF1), which is known to regulate gene expression. Nerve-specific siRNA-mediated knockdown of AUF1 inhibited prolonged hypersensitivity in females only, whereas overexpression of AUF1 in male DRG neurons increased pain-like responses. AUF1 knockdown was able to specifically inhibit repeated I/R-induced gene expression in females potentially downstream of prolactin receptor signaling. Data suggest RNA-binding proteins such as pAUF1 may underlie the sex-specific effects on DRG gene expression that modulates behavioral hypersensitivity after repeated I/R injury through prolactin signaling. This study may aid in finding distinct receptor differences related to the evolution of acute to chronic ischemic muscle pain development between sexes.

Temporal Dynamics of Pain: Examining the Relationship Between Intramuscular Injection Duration and Pain Perception: A Crossover Randomized Controlled Trial

Background Effective pain management is crucial for optimizing the patient experience and satisfaction with care. Many factors affect the intensity of injection pain, and one of these factors is the duration of the injection. This study aimed to evaluate the impact of intramuscular injection duration on perceived pain intensity in adults. Methods Fifty participants received injections according to a predetermined research protocol. Each participant served as their own control group. The intervention group was administered the drug over 40 seconds. The control group was given the same drug on the other side dorsogluteal region the following day, according to the unit's routine, in 10 seconds. Pain intensity was measured using the Wong-Baker Faces Pain Rating Scale and the Numerical Rating Scale. Statistical analysis was performed using SPSS (IBM Corp. Released 2017. IBM SPSS Statistics for Windows, Version 25.0. Armonk, NY: IBM Corp), including Wilcoxon and correlation analyses, with a significance level set at p < 0.05. Results The Wilcoxon test revealed a significant decrease in pain scores for the intervention group (p < 0.05), indicating that longer injection durations were associated with lower pain intensity. Significant correlations were found between hospital phobia and the use of pain relief measures, with pain perception (p < 0.05). Conclusion This research establishes a correlation between extended durations of intramuscular injections and pain intensity. These findings have implications for pain management during medical procedures and can contribute to optimizing patient comfort.

Specific back pain - effective diagnosis and treatment from the radiologist's point of view

The diagnosis and treatment of specific back pain is important in radiology. Due to the high number of patients suffering from back pain, it is important to provide excellent diagnostic and therapeutic support.Based on a recent literature search and considering the relevant guidelines as well as expert opinions, the aspects of specific back pain important for radiologists in terms of pathogenesis, diagnosis, and treatment are presented.Clinical examination in combination with the medical history provides a valid suspected diagnosis. This should subsequently be verified radiologically. MRI is the most effective cross-sectional diagnostic method for investigating specific back pain. A conventional X-ray on two planes in a standing position can be a useful addition if postural causes are suspected. If the clinical symptoms match the morphological findings, radiological treatment can be carried out for nerve root involvement as well as for inflammatory changes of the facet joints. The improvement in symptoms after radiological therapy is considered good overall; at least a short-term improvement in symptoms can generally be achieved, but no reliable data is available regarding the long-term outcome. Using preparations containing triamcinolone, low dosages should be selected in accordance with the guidelines. Embedding in a multimodal pain therapy treatment concept should be considered.Radiology provides essential diagnostic findings regarding specific back pain. Interventional pain therapy is an effective and safe method of treating proven specific back pain. · First examine clinically, then confirm the suspected diagnosis radiologically.. · MRI is usually the method of choice.. · Interventional pain therapy should show success after a maximum of 2 interventions.. · The anti-inflammatory drug dose should be kept as low as possible.. · The individual course determines the number of interventions.. · Stueckle CA, Haage P. Specific back pain - effective diagnosis and treatment from the radiologist's point of view. Fortschr Röntgenstr 2024; DOI 10.1055/a-2371-1752.

The relationship between myofascial trigger points sensitivity, cervical postural abnormality, and clinical tension-type headache parameters

BACKGROUND

Myofascial Trigger Points (MTrPs) play a significant role in the pathogenesis of Tension Type Headache (TTH). Abnormal cranio-cervical posture has been linked to various types of headaches. However, the correlation between MTrPs sensitivity, cervical postural alignment, and clinical measures of headache has not been extensively studied in patients with TTH.

OBJECTIVES

To investigate the relationship between MTrPs sensitivity in cervical and pericranial muscles, cervical postural abnormality, and clinical headache parameters in patients with TTH. Furthermore, to investigate the effect of sex on the examined variables and their association with headache type (episodic vs chronic TTH).

METHODS

A total of 72 patients with TTH of both sexes were enrolled in this study. Headache frequency and disability as clinical measures of headache, pressure pain threshold (PPT) of bilateral upper trapezius (UT) and suboccipital (SUB) muscles, cervical lordosis angle (CA), and anterior head translation (AHT) were measured.

RESULTS

Pericranial MTrPs sensitivity did not demonstrate any correlation with clinical headache parameters or cervical postural abnormality. However, there was a significant correlation between the frequency of headaches and the level of disability (r = 0.32, P < 0.05). In addition, episodic TTH was more prevalent in females who exhibited greater AHT and MTrPs sensitivity of both bilateral UT and right SUB muscles than males.

CONCLUSIONS

There was no correlation found between the frequency of headaches and the level of disability with measures of cervical posture alignment or MTrPs sensitivity in individuals with TTH.. Based on findings, Clinicians should consider sex differences when assessing patients with TTH.

Workplace Psychosocial Factors, Work Organization, and Physical Exertion as Risk Factors for Low Back Pain Among US Workers: Data From the 2015 National Health Interview Survey

OBJECTIVE

To evaluate the association between workplace psychosocial, organization, and physical risk factors with low back pain (LBP) among US workers.

METHODS

2015 National Health Interview Survey data were analyzed to calculate the prevalence rates and prevalence ratios for LBP across levels of workplace psychosocial and organizational risk factors among 17,464 US adult workers who worked ≥20 hours per week. Results were also stratified by workplace physical exertion.

RESULTS

The adjusted prevalence rates of LBP were significantly elevated for workers reporting high job demand, low job control, work-family imbalance, bullying, job insecurity, working alternate shifts, and physical exertion. Job control and nonstandard shifts were significantly associated with LBP only among those who reported low/no physical exertion.

CONCLUSIONS

LBP prevalence was associated with select workplace psychosocial and organization risk factors. Stratification by physical exertion modified multiple associations.

Evaluation of three decades of the burden of low back pain in China before COVID-19: Estimates from the Global Burden of Disease Database 2019

Background

Low back pain (LBP) is reported as an urgent public-health concern globally because it occurs in all age groups and is now the leading cause of disability, with health systems unable to cope with this burden. We present China's burden of LBP by estimating its prevalence and years lived with disability (YLDs) from 1990 to 2019.

Methods

We obtained the data relating to LBP from the Global Burden of Disease Database (GBD) 2019. Then we calculated years lived with disability caused by LBP by multiplying the prevalence of LBP sequelae by their corresponding disability weights. We performed an analysis of the age-, sex-, and province-specific prevalence and YLDs of 33 provinces/regions in China, as well as their relationship with the sociodemographic index (SDI).

Results

China has the largest numbers of people with LBP (91.3 million) and YLDs (8.6 million) globally, and LBP is the leading cause of YLDs. The age-standardised prevalence was 7.25% in 1990, and this decreased to 5.13% in 2019. The age-standardised YLD rate was 579/100 000 in 2019, having decreased by 28.97%. Both measurements increased with age, being higher in women and varying across the 33 provinces/regions. For the 5-to-14-year age group, the prevalence (4.50%) and YLD rate (4.51%) increased in 2019 from 1990 (3.21% and 3.21%, respectively) when compared to the elderly group. Age-standardised YLD rates experienced decreases with increasing SDI, while there was an increasing tendency as SDI increased further; the changes for women were more obvious.

Conclusions

Over the three decades considered, China has continued to have the largest number of people with LBP in the world, even though the age-standardised prevalence has decreased. YLDs were found to decrease as SDI increased, but they subsequently increased again. LBP still presents a burden, particularly for children and postmenopausal women.

Effects of Nature-Based Multisensory Stimulation on Pain Mechanisms in Women with Fibromyalgia Syndrome: A Randomized Double-Blind Placebo-Controlled Trial

BACKGROUND

The term "nature-based sensory stimuli" refers to the sensory information produced by biotic and abiotic agents from natural environments. The literature has reported the beneficial effects of these agents on various pain dimensions in non-clinical populations.

AIMS

To evaluate the potential analgesic effects of nature-based multisensory stimulation in women with fibromyalgia syndrome.

METHODS

A randomized, double-blind, placebo-controlled, parallel-group trial with a 1:1 allocation ratio was conducted. Forty-two women with fibromyalgia syndrome interacted with either different plant species with flowers, stones, and soil organic matter or their synthetic imitations for 30 minutes. Outcome measurements were performed before and after the intervention, including clinical pain intensity using the Numeric Rating Scale, cold pain thresholds using the Cold Pressor Test, mechanical hyperalgesia and wind-up using a monofilament, and pressure pain thresholds using a pressure algometer.

RESULTS

Analyses revealed group × time interactions for clinical pain intensity (F = 7.915, p = .008), cold-water immersion time (F = 7.271, p = .010), mechanical hyperalgesia (F = 4.701, p = .036), and pressure pain threshold (p ≤ .017). Between-group differences were found in clinical pain intensity (p = .012), cold pain thresholds (p = .002), and pressure pain thresholds (p < .05). The experimental group exhibited reduced clinical pain intensity (p = .001) and increased pressure pain thresholds (p ≤ .034).

CONCLUSIONS

Women with fibromyalgia syndrome may benefit from multisensory stimulation using biotic and abiotic agents from natural environments for 30 minutes. Interacting with flowering plants and soil components appears to induce analgesic effects.

Physical and psychosocial work demands associated with pain and disability among skilled male Arab waiters

BACKGROUND

Physical and psychosocial demands (e.g., serving, cleaning, fulfilling orders) can lead to work-related musculoskeletal pain (WRMSP).

OBJECTIVE

To assess the prevalence of WRMSP in the upper quadrant and lower back among skilled male Arab waiters; to evaluate the disability related to WRMSP; to evaluate the association between work demands and WRMSP with related disability.

METHODS

100 skilled male Arab waiters working full-time, aged 18-60, participated in the cross-sectional study. Participants completed basic demographics and working conditions; the NDI; QuickDASH; the OswestryQ; workload, burnout, and job satisfaction at work; the adjusted NordicQ; and the TaskQ, compiled especially for this study.

RESULTS

A 12-month pain prevalence, pain frequency, and work avoidance were high: neck- 42%, 60.5%, 89.5%; shoulders -53%, 78.2%, 94.4%; elbows- 46%, 78.6%, 83.3%; lower back- 45%, 44%, 78.7%, respectively. Pain prevalence in at least one site was 83%. The OswestryQ, QuickDASH, and NDI revealed mild-moderate pain and disability (14.85/50, 25.54/75, 13.74/50, respectively). Burnout score was positively associated with OswestryQ, QuickDASH, and NDI. Job satisfaction was negatively associated with 12 months of pain in the lower back, hands, arms, shoulders, and hands (NordicQ). TaskQ was positively associated with OswestryQ.

CONCLUSION

Male Arab waiters who work in physically and psychologically challenging conditions report high levels of WRMSP with a high frequency and related work avoidance. Many of them must keep their jobs as they are their families' primary or sole providers. It is possible that they are trying to prevent more severe disabilities in the future by ensuring temporary rest and pain prevention.

Involvement of the Transient Receptor Channels in Preclinical Models of Musculoskeletal Pain

BACKGROUND

Musculoskeletal pain is a condition that affects bones, muscles, and tendons and is present in various diseases and/or clinical conditions. This type of pain represents a growing problem with enormous socioeconomic impacts, highlighting the importance of developing treatments tailored to the patient's needs. TRP is a large family of non-selective cation channels involved in pain perception. Vanilloid (TRPV1 and TRPV4), ankyrin (TRPA1), and melastatin (TRPM8) are involved in physiological functions, including nociception, mediation of neuropeptide release, heat/cold sensing, and mechanical sensation.

OBJECTIVE

In this context, we provide an updated view of the most studied preclinical models of muscle hyperalgesia and the role of transient receptor potential (TRP) in these models.

METHODS

This review describes preclinical models of muscle hyperalgesia induced by intramuscular administration of algogenic substances and/or induction of muscle damage by physical exercise in the masseter, gastrocnemius, and tibial muscles.

RESULTS

The participation of TRPV1, TRPA1, and TRPV4 in different models of musculoskeletal pain was evaluated using pharmacological and genetic tools. All the studies detected the antinociceptive effect of respective antagonists or reduced nociception in knockout mice.

CONCLUSION

Hence, TRPV1, TRPV4, and TRPA1 blockers could potentially be utilized in the future for inducing analgesia in muscle hypersensitivity pathologies.

Topical application of a TRPA1 antagonist reduced nociception and inflammation in a model of traumatic muscle injury in rats

Musculoskeletal pain is a widely experienced public healthcare issue, especially after traumatic muscle injury. Besides, it is a common cause of disability, but this pain remains poorly managed. However, the pathophysiology of traumatic muscle injury-associated pain and inflammation has not been fully elucidated. In this regard, the transient receptor potential ankyrin 1 (TRPA1) has been studied in inflammatory and painful conditions. Thus, this study aimed to evaluate the antinociceptive and anti-inflammatory effect of the topical application of a TRPA1 antagonist in a model of traumatic muscle injury in rats. The mechanical trauma model was developed by a single blunt trauma impact on the right gastrocnemius muscle of Wistar male rats (250-350 g). The animals were divided into four groups (Sham/Vehicle; Sham/HC-030031 0.05%; Injury/Vehicle, and Injury/HC-030031 0.05%) and topically treated with a Lanette® N cream base containing a TRPA1 antagonist (HC-030031, 0.05%; 200 mg/muscle) or vehicle (Lanette® N cream base; 200 mg/muscle), which was applied at 2, 6, 12, 24, and 46 h after muscle injury. Furthermore, we evaluated the contribution of the TRPA1 channel on nociceptive, inflammatory, and oxidative parameters. The topical application of TRPA1 antagonist reduced biomarkers of muscle injury (lactate/glucose ratio), spontaneous nociception (rat grimace scale), inflammatory (inflammatory cell infiltration, cytokine levels, myeloperoxidase, and N-acetyl-β-D-glucosaminidase activities) and oxidative (nitrite levels and dichlorofluorescein fluorescence) parameters, and mRNA Trpa1 levels in the muscle tissue. Thus, these results demonstrate that TRPA1 may be a promising anti-inflammatory and antinociceptive target in treating muscle pain after traumatic muscle injury.

Gender-Related Issues in the Management of Low-Back Pain: A Current Concepts Review

BACKGROUND

Low back pain (LBP) is an emerging disease. This review aims to investigate the role of gender-related factors in the diagnosis, clinical, and surgical management of LBP.

METHODS

From January 2002 to March 2023, EMBASE, SCOPUS, OVID-MEDLINE, Google Scholar, PubMed, and Web of Science were searched to identify relevant papers for further analysis.

RESULTS

Fifteen papers were included in this review. Sex- and gender-related differences were analyzed regarding the following points: (1) LBP epidemiology; (2) LBP physiopathology; (3) conservative management of LBP; (4) major vertebral surgery for LBP. The conservative treatment of LBP highlights that women claim services later in terms of poorer health status than men. In the postoperative phase, female patients show worse LBP, quality of life, and disability, but equal or greater interval change, compared with male patients complaining of lumbar degenerative disease.

CONCLUSIONS

LBP epidemiology and clinical outcomes, following conservative and surgical management of patients complaining of back pain, might depend on both sex- and gender-related factors. It is mandatory to assess gender-related indicators in patients referred to LBP and address them to improve their clinical outcomes and quality of life.

Sex specific role of RNA-binding protein, AUF1, on prolonged hypersensitivity after repetitive ischemia with reperfusion injury

Repetitive ischemia with reperfusion (I/R) injury is a common cause of myalgia. I/R injuries occur in many conditions that differentially affect males and females including complex regional pain syndrome and fibromyalgia. Our preclinical studies have indicated that primary afferent sensitization and behavioral hypersensitivity due to I/R may be due to sex specific gene expression in the DRGs and distinct upregulation of growth factors and cytokines in the affected muscles. In order to determine how these unique gene expression programs may be established in a sex dependent manner in a model that more closely mimics clinical scenarios, we utilized a newly developed prolonged ischemic myalgia model in mice whereby animals experience repeated I/R injuries to the forelimb and compared behavioral results to unbiased and targeted screening strategies in male and female DRGs. Several distinct proteins were found to be differentially expressed in male and female DRGs, including AU-rich element RNA binding protein (AUF1), which is known to regulate gene expression. Nerve specific siRNA-mediated knockdown of AUF1 inhibited prolonged hypersensitivity in females only, while overexpression of AUF1 in male DRG neurons increased some pain-like responses. Further, AUF1 knockdown was able to specifically inhibit repeated I/R induced gene expression in females but not males. Data suggests that RNA binding proteins like AUF1 may underlie the sex specific effects on DRG gene expression that modulate behavioral hypersensitivity after repeated I/R injury. This study may aid in finding distinct receptor differences related to the evolution of acute to chronic ischemic muscle pain development between sexes.

Regulatory T-cells and IL-5 mediate pain outcomes in a preclinical model of chronic muscle pain

Fibromyalgia (FM) is a chronic musculoskeletal pain disorder primarily diagnosed in women. Historically, clinical literature focusing on cytokines and immune cells has been inconsistent. However, recent key studies show several layers of immune system dysfunction in FM. Preclinically, studies of the immune system have focused on monocytes with little focus on other immune cells. Importantly, T-cells are implicated in the development and resolution of chronic pain states, particularly in females. Our previous work showed that monocytes from women with FM produced more interleukin 5 (IL-5) and systemic treatment of IL-5 reversed mechanical hypersensitivity in a preclinical model of FM. Typically, IL-5 is produced by T_H2-cells, so in this study we assessed T-cell populations and cytokine production in female mice using the acid-induced chronic muscle pain model of FM before and after treatment with IL-5. Two unilateral injections of pH4.0 saline, five days apart, into the gastrocnemius muscle induce long-lasting widespread pain. We found that peripheral (blood) regulatory T_helper-cells (CD4⁺ FOXP3+) are downregulated in pH4.0-injected mice, with no differences in tissue (lymph nodes) or CD8⁺ T-cell populations. We tested the analgesic properties of IL-5 using a battery of spontaneous and evoked pain measures. Interestingly, IL-5 treatment induced place preference in mice previously injected with pH4.0 saline. Mice treated with IL-5 show limited changes in T-cell populations compared to controls, with a rescue in regulatory T-cells which positively correlates with improved mechanical hypersensitivity. The experiments in this study provide novel evidence that downregulation of regulatory T-cells play a role in chronic muscle pain pathology in the acidic saline model of FM and that IL-5 signaling is a promising target for future development of therapeutics.

The Role of Sex Hormones in Pain-Related Conditions

Millions of people are affected by pain-related conditions worldwide. Literature has consistently shown that each individual experiences and perceives pain in a unique manner due to biological, environmental, and cultural factors in which they have been raised. It has been established that biological males and females perceive pain differently and that it may be partially explained by their distinct hormonal profiles since birth, which are only further magnified during puberty. For biological males, high levels of testosterone have shown to increase their pain threshold; and for biological females, estrogen fluctuations have shown to increase pain intensity and perception. However, sex hormones have not been studied in the context of pain treatment or their impact on biochemical pathways involved in pain perception. For this purpose, the transgender community serves as a unique population to investigate the impact of hormone replacement therapy on molecular pathways involved in the perception of pain. The purpose of this review is to explore the biochemistry of hormone replacement in transgender patients who also have other pain-related conditions such as headaches, fibromyalgia, temporomandibular myalgia, and visceral pain.

Effects of a Family Caregiver Care Programme in Musculoskeletal Pain and Disability in the Shoulder-Neck Region-A Randomised Clinical Trial

Life expectancy in Spain has increased and older people need more health care to improve their quality of life. The high demands of the population sometimes collapse health services, making them insufficient to cover their needs, which leads to the development of “non-professional caregivers”. These caregivers have suffered musculoskeletal injuries of the cervical spine and shoulders and should be guided and assessed on ergonomics, biomechanics, or kinesiotherapy. However, there are no interventions to help them care for themselves. This study presents the application of a physical exercise programme to prevent these disorders in women caregivers of dependent patients. It consists of a randomised controlled clinical trial with two groups: both received a family caregiver care programme, and the intervention group also received a physical therapeutic exercise programme for 12 weeks. A total of 62 caregivers completed the study, who were mostly daughters or wives of dependents. Of these, 70.97% presented a “moderate” pain intensity and a cervical disability of 13.72 ± 7.64 points in the NDI questionnaire in the initial evaluation. In the intervention group of caregivers, there was a significant decrease in the pain intensity and a significant increase (p < 0.05) in all cervical joint amplitude movements. Caregivers present a high prevalence of musculoskeletal disorders. The physical exercise programme was effective in reducing the intensity of pain, lumbar disability, and cervical disability of the family caregivers.

Prevalence, Patterns, and Risk Factors of Work-Related Musculoskeletal Diseases Among Teachers in the Eastern Province, Saudi Arabia: A Community-Based Retrospective Cross-Sectional Survey

Background and objective Work-related musculoskeletal diseases (WMSDs) are one of the most common occupational health concerns among teachers. They refer to a variety of degenerative and inflammatory disorders that can be triggered by the work environment of the people affected. Teachers' health is substantially significant as it impacts their productivity at work. The aim of this study was to determine the prevalence, patterns, implications, and risk factors of WMSDs among teachers in the Eastern Province of Saudi Arabia. Methods This study involved a survey based on a cross-sectional questionnaire that was distributed to 404 random school teachers located in the Eastern province of Saudi Arabia. Information such as sociodemographic characteristics, workplace characteristics, characteristics of WMSDs experienced, associated factors, and impact of the symptoms experienced was collected. Questions related to symptoms were obtained from the Nordic Musculoskeletal Questionnaire and Örebro Musculoskeletal Pain Screening Questionnaire (ÖMPSQ). The collected data were then analyzed using the SPSS Statistics version 23.0 (IBM Corp., Armonk, NY). Results Among the participants, back pain, shoulder pain, and knee pain were the most reported symptoms of WMSDs in the past 12 months, while elbow pain was the least experienced; 41.1% had pain, discomfort, or numbness that prevented them from performing regular daily activities. The regression analysis revealed a relationship between moderate to severe pain and a pain duration of more than 12 months (p=0.001). Additionally, those who were able to perform lighter work and were not having depression had a low probability of pain persistence and were able to carry out their usual work while experiencing pain (p=0.002). Conclusions In the Eastern province of Saudi Arabia, WMSDs were commonly reported by school teachers. The prevalence of WMSDs among teachers was 41.1%. The pain was described as disabling and causing a negative impact on performance. The most common locations of symptoms were the back, shoulder, and knees. Risk factors for severe pain were female gender, sleeping for six to seven hours, and pain located in the neck shoulder, elbow, hand, thigh/hips, back, knees, and ankles. Furthermore, severe pain was associated with pain duration of more than 12 months, affecting sleep, causing anxiety, and mild depression. The impact of severe pain seriously affected the daily activities of teachers.

Sex-Related Pain Behavioral Differences following Unilateral NGF Injections in a Rat Model of Low Back Pain

Low back pain (LBP) is a globally prevalent and costly societal problem with multifactorial etiologies and incompletely understood pathophysiological mechanisms. To address such shortcomings regarding the role of neurotrophins in the underlying mechanisms of pain, an LBP model was developed in rats involving two unilateral intramuscular injections of nerve growth factor (NGF) into deep trunk muscles. To date, behavioral investigations of this NGF-LBP model have been limited, especially as it pertains to female pain behaviors. This study compared mechanical sensitivity to noxious (hyperalgesia) and non-noxious (hypersensitivity) stimuli in control and NGF-injected male and female rats through pain resolution. Although the baseline testing revealed no differences between males and females, NGF-injected females demonstrated prolonged ipsilateral deep trunk mechanical hyperalgesia that resolved seven days later than males. Moreover, females showed bilateral trunk mechanical sensitivity to noxious and non-noxious stimuli compared to only ipsilateral behaviors in males. Sex differences were also observed in the severity of behavioral responses, with females displaying greater mean differences from baseline at several timepoints. Overall, these NGF-LBP behavioral findings mirror some of the sex differences reported in the clinical presentation of LBP and accentuate the translatability of this NGF-LBP model. Future studies using this LBP-NGF model could help to elucidate the neurobiological mechanisms responsible for the development, severity, and/or resolution of muscular LBP as well as to provide insights into the processes governing the transition from acute to chronic LBP.

Potential Nociceptive Role of the Thoracolumbar Fascia: A Scope Review Involving In Vivo and Ex Vivo Studies

Nociceptive innervation of the thoracolumbar fascia (TLF) has been investigated over the past few decades; however, these studies have not been compiled or collectively appraised. The purpose of this scoping review was to assess current knowledge regarding nociceptive innervation of the TLF to better inform future mechanistic and clinical TLF research targeting lower back pain (LBP) treatment. PubMed, ScienceDirect, Cochrane, and Embase databases were searched in January 2021 using relevant descriptors encompassing fascia and pain. Eligible studies satisfied the following: (a) published in English; (b) preclinical and clinical (in vivo and ex vivo) studies; (c) original data; (d) included quantification of at least one TLF nociceptive component. Two-phase screening procedures were conducted by a pair of independent reviewers, after which data were extracted and summarized from eligible studies. The search resulted in 257 articles of which 10 met the inclusion criteria. Studies showed histological evidence of nociceptive nerve fibers terminating in lower back fascia, suggesting a TLF contribution to LBP. Noxious chemical injection or electrical stimulation into fascia resulted in longer pain duration and higher pain intensities than injections into subcutaneous tissue or muscle. Pre-clinical and clinical research provides histological and functional evidence of nociceptive innervation of TLF. Additional knowledge of fascial neurological components could impact LBP treatment.

Prevalence and Factors Associated with Musculoskeletal Disorders among Secondary Schoolteachers in Hail, Saudi Arabia: A Cross-Sectional Survey

Musculoskeletal disorders (MSDs) are one of the most common occupational health hazards and serious health concerns among teachers. About 39% to 95% of teachers suffer from musculoskeletal pain that can lead to a decline in their performance, frequent sick leaves and early retirement, and can have a negative impact on their quality of life. The aim of this study was to investigate the prevalence of and risk factors for MSDs among secondary schoolteachers in Hail, Saudi Arabia. A cross-sectional study was conducted through an electronic survey. A self-reported and validated Arabic version of the Nordic Musculoskeletal Questionnaire (NMQ) was used. Participants were recruited randomly through a two-stage sampling technique. A total of 251 respondents (57.8% males and 42.2% females) returned the questionnaire. The overall prevalence of MSDs was 87.3%. Female teachers (95.3%) suffered more than their male counterparts (81.4%). The most common site was the lower back (62.55%), followed by the shoulders (53.39%) and knees (41.04%). Most of the participants (72.7%) reported MSDs in multiple sites. Binomial logistic regression predicted that smoking is a significant risk factor for lower back disorders (p < 0.05). A high prevalence of MSDs can be due to a substantial lack of awareness and practice of ergonomics, which warrant the development of preventive strategies and educational programs.

Total Training Volume and Muscle Soreness Parameters Performing Agonist or Antagonist Foam Rolling between Sets

Background: Foam rolling (FR) has become very popular in recent years; however, the practice of FR between sets of resistance training (RT) for the lower limbs needs further examination. Purpose: Therefore, the purpose of the present study was to examine the effect of FR for the agonists (quadriceps) and antagonists (hamstrings) between multiple sets of the leg extension on repetition maximum performance (RM), fatigue resistance index (FRI), and muscle soreness (MS). Study design: Quasi-experimental clinical trial. Methods: Twenty trained men participated in this study (30.35 ± 6.56 years, 1.77 ± 0.05 cm, 87.70 ± 7.6 kg) and attended seven sessions with 48 h between sessions, (one familiarization session; two 10-RM test and retest sessions; and four experimental sessions). The four experimental sessions were performed in random order and included: agonist foam rolling (AFR), antagonist foam rolling (ANTFR), agonist/antagonist foam rolling (A/ANTFR), and traditional control (TP, without foam rolling). All sessions consisted of three sets for maximal repetitions with a 10-RM load for the leg extension. In the AFR and ANTFR sessions, there was a 120 s rest interval between sets, during which FR was done for the agonists or antagonists, respectively. In the A/ANTFR protocol, there was a 120 s rest interval between sets, during which FR was done for the agonists and antagonists. In the traditional protocol (TP), there was a 120 s passive rest interval between sets. Results: Regarding the total training volume (TTV), significant differences were noted between sessions (F_3,57 = 11.014; p = 0.0001). The AFR, ANTFR, and A/ANTFR sessions had significantly higher TTV versus the TP (p < 0.05). Regarding the FRI, significant differences were noted between sessions (F_3,57 = 2917, p = 0.042). A significantly higher fatigue index was shown for the ANTFR and AFR sessions versus the TP (p < 0.05). Regarding the total number of repetitions, significant differences were noted between sessions (F_3,57 = 11.086, p = 0.0001). The total number of repetitions was significantly higher in the A/ANTFR, ANTFR, and AFR versus the TP session (p < 0.05). MS was significantly lower in the A/ANTFR, ANTFR, and AFR sessions versus the TP session (p < 0.05). Conclusion: In conclusion, foam rolling between sets for the agonist or antagonist separately or in succession, resulted in greater neuromuscular performance and higher fatigue indices, as well as reducing the perception of acute muscle soreness.

Pathophysiology of musculoskeletal pain: a narrative review

Musculoskeletal pain (excluding bone cancer pain) affects more than 30% of the global population and imposes an enormous burden on patients, families, and caregivers related to functional limitation, emotional distress, effects on mood, loss of independence, and reduced quality of life. The pathogenic mechanisms of musculoskeletal pain relate to the differential sensory innervation of bones, joints, and muscles as opposed to skin and involve a number of peripheral and central nervous system cells and mediators. The interplay of neurons and non-neural cells (e.g. glial, mesenchymal, and immune cells) amplifies and sensitizes pain signals in a manner that leads to cortical remodeling. Moreover, sex, age, mood, and social factors, together with beliefs, thoughts, and pain behaviors influence the way in which musculoskeletal pain manifests and is understood and assessed. The aim of this narrative review is to summarize the different pathogenic mechanisms underlying musculoskeletal pain and how these mechanisms interact to promote the transition from acute to chronic pain.

Pharmacogenomics and prescription opioid use

Genome-wide association studies and candidate gene findings suggest that genetic approaches may help in choosing the most appropriate drug and dosage, while preventing adverse drug reactions. This is the field that addresses precision medicine: to evaluate variations in the DNA sequence that could be responsible for different individual analgesic response. We review potential gene biomarkers with best overall convergent functional evidence, for opioid use, in pain management. Polymorphisms can modify pharmacodynamics (i.e., mu opioid receptor, OPRM1) and pharmacokinetics (i.e., CYP2D6 phenotypes) pathways altering opioid effectiveness, consumption, side effects or additionally, prescription opioid use dependence vulnerability. This review provides a summary of these candidate variants for the translation of genotype into clinically useful information in pain medicine.