Sleep disturbances and severe stress as glial activators: key targets for treating central sensitization in chronic pain patients?

Mendelian Randomization Analysis Identifies Causal Effects of Multi-Site Chronic Pain on Obstructive Sleep Apnea

Background

Observational studies have suggested an association between obstructive sleep apnea (OSA) and chronic pain disorders, but causal evidence have not been confirmed.

Methods

Here we performed Mendelian randomization (MR) study to explore the potential causal association and mediating roles of modifiable factors between multi-site chronic pain (MCP) and OSA. Independent single nucleotide polymorphisms (SNPs) (N=26) from MCP GWAS (n=387,649) in the UK Biobank were used as instrumental variables to test associations with OSA from the FinnGen consortium, which encompassed 16,761 individuals with OSA cases and 201,194 individuals without OSA.

Results

MR analyses provide genetic evidence to predict MCP on the risk of OSA. Specifically, a per-site increase in multi-site chronic pain was linked to a 184% higher risk of OSA (ORIVW = 1.84, 95% CI = 1.29-2.63, p = 7.24×10-4). However, we also performed reverse association analyses and found no significant casual effect of OSA on MCP. MR estimates were in agreement regardless of the method used, such as MR-egger, weighted median and weighted mode, thereby demonstrating the accuracy of the causal associations. Through mediation analyses, we found that body mass index (BMI), waist circumference, and educational attainment explained a substantial proportion of the association between MCP and OSA (proportion mediated=21.13%; 26.57% and 9.66% respectively).

Conclusion

Our findings suggest that both pain management interventions, prevention of obesity and health education are likely to be effective strategies to reduce OSA risk in individuals with MCP.

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).

The associations between sleep problems and pain outcomes in people with hand osteoarthritis - Data from the Nor-hand study

Objective

To examine the relation of sleep problems to pain outcomes in people with hand osteoarthritis, and the extent to which central sensitization mediates these relationships.

Design

In total 299 participants from the Nor-Hand cohort study rated their sleep problems (no, slight, moderate or severe problems), hand pain intensity on a Numeric Rating Scale (NRS, range: 0-10) and Australian/Canadian Osteoarthritis Hand Index (AUSCAN; range: 0-20), and overall bodily pain intensity (NRS). Central sensitization was evaluated by quantitative sensory testing. All pain questionnaires were repeated after 3.5 years. We explored the associations between sleep problems at baseline and pain outcomes at baseline and follow-up and fitted natural effect models to examine the extent to which measures of central sensitization mediated the effects of sleep problems on pain. All main analyses were adjusted for age, sex, education, comorbidities, and body mass index.

Results

Slight, moderate, and severe sleep problems were reported by 33.8 ​%, 26.8 ​% and 14.3 ​%, respectively. In general, individuals with severe versus without sleep problems reported relatively more intense pain at baseline and follow up (i.e., a 1.68 (95 ​% confidence interval 0.89-2.46) higher NRS hand pain at baseline). Associations between sleep and central sensitization were weak, with no mediating effects found. For example, the indirect effect of remote pressure pain thresholds was 0.06 (-0.27, 0.39) NRS points for hand pain among individuals reporting severe sleep problems.

Conclusion

Sleep problems are commonly reported and related to pain intensity in people with hand osteoarthritis, while the underlying mechanisms and temporal relationship remain unclear.

Sensory profiles and their role in the persistence of central sensitization symptoms in low back pain. A prospective cohort study

INTRODUCTION

Acute lower back pain can lead to neuroplastic changes in the central nervous system, and symptoms of central sensitization after 12 weeks. While sensory sensitivity has been shown to predict symptoms of central sensitization, trait sensory profiles may be prognostic in the persistence of central sensitization symptoms in low back pain over time.

OBJECTIVE

To examine sensory profiles as prognostic symptoms of central sensitization in people with acute low back pain.

METHODS

A longitudinal type 2 prognostic factor research study was performed according to the PROGRESS framework. Baseline and 12-week follow-up measures were taken using the Adolescent/Adult Sensory Profile and the Central Sensitization Inventory measures. Study participants were consecutively included from primary care physiotherapy practices. Univariable, and multivariable regression analyses were performed to adjust sensory profiles based on previous history of low back pain, baseline Central Sensitization Inventory scores, level of pain, disability, age, and duration of low back pain.

RESULTS

After adjustment, the sensory profiles of Low Registration B = 0.44, 95%CI (0.18, 0.70), Sensation Seeking B = 0.38, 95%CI (0.19, 0.57), Sensory Sensitive B = 0.49, 95%CI (0.25, 0.74), Sensation Avoiding B = 0.40, 95% CI (0.15, 0.65) was significantly associated with the persistence of central sensitization symptoms (N = 103).

CONCLUSION

Sensory profiles may predict symptoms of central sensitization after 12 weeks in people with acute low back pain.

Sex-Specific Sensory Profiles Discriminate Between Sensitization at Twelve Weeks in Patients with Acute Low Back Pain: A Retrospective Study

Background/objective: Low back pain (LBP) is the leading cause of disability worldwide, resulting in enormous socio-economic and personal consequences. Sensory profiles during the acute back pain stage will predict central sensitization symptoms in the chronic pain stage, as central sensitization is the main mechanism behind nociplastic pain and pain chronicity. Therefore, our objective was to establish overall and sex-specific sensory profile cut-off points that distinguish symptoms of central sensitization at 12 weeks, using a retrospective prognostic cohort study design. Methods: Two hundred and seventeen patients with acute LBP (<6 weeks) were assessed using Receiver Operator Characteristic analyses. Measurements were taken at baseline using the Adolescent/Adult Sensory Profile and follow-up by the Central Sensitization Inventory at 12 weeks, based on the established Central Sensitization Inventory cut-off points for the overall population at ≥30 and ≥40, female patients at ≥33, and male patients at ≥25. Results: In female patients, a Sensory Sensitive cut-off point of ≥30.5 significantly distinguished central sensitization symptoms at 12 weeks, resulting in the following values: Area Under the Curve = 0.81 (95% CI = 0.73; 0.89), sensitivity = 0.89, specificity = 0.63, prevalence = 0.36, positive predictive value = 0.56, negative predictive value = 0.80, and Youden's index = 0.52. Conclusions: The Sensory Sensitive profile distinguishes female patients with acute LBP with and without central sensitization symptoms at 12 weeks. This cut-off point may be useful in identifying individual sensory preferences and addressing maladaptive behavioral responses to sensory stimulation in clinical practice to prevent chronicity.

Subgroup Characteristics of Middle-Aged and Older Women with Chronic Low Back Pain by Multiple Factors: A Hierarchical Cluster Analysis

BACKGROUND/OBJECTIVES

Chronic low back pain (CLBP) after middle age is a complex multifactorial condition, and subgrouping is recommended to determine effective treatment strategies. Multidimensional data help create new groupings to increase the effectiveness of interventions in middle-aged and older adults with CLBP. This study aimed to investigate the relationship between the factors associated with CLBP after middle age and to create and characterize a new subgroup based on these factors.

METHODS

A cross-sectional observational study was conducted and included 46 women aged ≥40 years with CLBP who participated in health events. Trunk muscle mass, lumbar movement control ability, autonomic balance, lumbar tenderness threshold, lumbar proprioception, and severity of central sensitization were assessed.

RESULTS

Partial correlation analysis revealed a significant negative correlation between lumbar movement control ability and autonomic balance. A significant positive correlation was observed between trunk muscle mass and the lumbar tenderness threshold. Hierarchical clustering analysis identified three subgroups. The cluster 1 participants had low trunk muscle mass, low tenderness threshold, and low severity of central sensitization. The cluster 2 participants had low trunk muscle mass and tenderness threshold and high severity of central sensitization. The cluster 3 participants had high trunk muscle mass and tenderness threshold and were sympathetically predominant. Trunk muscle mass, pressure pain threshold, severity of central sensitization, and autonomic balance were significantly different between the clusters.

CONCLUSIONS

Three characteristic subgroups were identified. The results contribute to treatment and prevention strategies for middle-aged and older adults with CLBP based on the characteristics of the subgroups rather than a uniform approach.

Estrogen receptor α regulates the IKKs/NF-kB activity involved in the development of mechanical allodynia induced by REM sleep deprivation in rats

Several signaling pathways that converge in NF-kB activation have been linked to developing and maintaining different types of pathological pain. In addition, some mechanisms implied in the establishment of chronic pain have been demonstrated to have a sex-dependent correlation. This study aimed to determine if the IKKs/NF-kB signaling pathway is involved in establishing REM sleep deprivation (REMSD) induced mechanical allodynia in rats and its possible regulation depending on estradiol and estrogen receptors. Intrathecal administration of BMS-345541 or minocycline, two drugs that reduce the IKKs/NF-kB activity, avoided the development of mechanical allodynia in female but not in male rats subjected to 48 h of REMSD. Ovariectomy in female rats abolished the effect of BMS-345541 and minocycline. Meanwhile, the 17-β-estradiol restitution restored it. Intrathecal administration of MPP, a selective ERα antagonist, but not PHTPP, a selective ERβ antagonist, avoided the effect of BMS-345541 in female rats without hormonal manipulation. In addition, the transient run-down of ERα in female rats abolished the effect of BMS-345541. All data suggest an important role of ERα as a regulator of the IKKs/NF-kB activity. REMSD increased the ERα protein expression in the dorsal root ganglia and the dorsal spinal cord in females but not in male rats. Interestingly, ERα activation or ERα overexpression allowed the effect of BMS-345541 in male rats. Data suggest an important regulatory role of ERα in the IKKs/NF-kB activity on establishing mechanical allodynia induced by REMSD in female rats.

The bidirectional relationship between sleep problems and chronic musculoskeletal pain: a systematic review with meta-analysis

ABSTRACT

Chronic musculoskeletal pain and sleep problems/disorders exhibit a recognized bidirectional relationship; yet, systematic investigations of this claim, particularly in a prospective context, are lacking. This systematic review with meta-analysis aimed to synthesize the literature on the prospective associations between sleep problems/disorders and chronic musculoskeletal pain. A comprehensive search across 6 databases identified prospective longitudinal cohort studies in adults examining the relationship between sleep problems/disorders and chronic musculoskeletal pain. Random-effects meta-analyses, using the Hartung-Knapp adjustment for 95% confidence intervals (CIs), were conducted, and all results were presented as odds ratios (ORs). Certainty of evidence was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluations approach. Including 16 articles from 11 study populations (116,746 participants), meta-analyses indicated that sleep problems at baseline may heighten the risk of chronic musculoskeletal pain in both short term (OR 1.64, 95% CI 1.01-2.65) and long term (OR 1.39, 95% CI 1.21-1.59). The evidence for different sleep problem categories was very uncertain. Chronic musculoskeletal pain at baseline may increase the risk of short-term sleep problems (OR 1.56, 95% CI 1.02-2.38), but long-term evidence was very uncertain. The impact of only local or only widespread pain on short-term sleep problems was very uncertain, whereas widespread pain may elevate the risk of long-term sleep problems (OR 2.0, 95% CI 1.81-2.21). In conclusion, this systematic review with meta-analysis suggests that sleep problems are associated with an increased risk of chronic musculoskeletal pain, but the bidirectional nature of this relationship requires further investigation.

Association between Drug Use and Perception of Mental Health in Women Diagnosed with Fibromyalgia: An Observational Study

BACKGROUND/OBJECTIVES

Fibromyalgia (FM) is a chronic syndrome characterized by widespread musculoskeletal pain, fatigue, sleep disturbances, and mental health issues. It affects approximately 1.78% of the general population; an estimated 4:1 ratio between women and men is observed. It significantly impacts quality of life and carries both clinical and social stigma. This study aims to evaluate the relationship between drug use and mental health in female patients with fibromyalgia.

METHODS

This study is prospective, observational, and cross-sectional. A questionnaire was administered to 544 subjects, achieving a representative sample size from a population of 800,000 subjects by using an algorithm for proportion estimation with a known sampling frame. The selection was non-random, making the sampling non-probabilistic. Logistic regression models were applied to assess the effect of drug use on perception of mental health; presence of symptoms such as comprehension and memory problems, insomnia, depression, and anxiety; and severity of cognitive symptoms and non-restorative sleep. To quantify the impact, odds ratios and confidence intervals have been observed.

RESULTS

The findings indicate the non-recommended use of medications and reveal the ineffectiveness and adverse effects of drug interactions on mental health. The use of benzodiazepines and sedative-hypnotics is significantly associated with a negative perception of mental health. Benzodiazepines do not improve symptoms or significantly reduce their severity. SSRI antidepressants do not enhance mental health perception; however, when used exclusively, they are effective in reducing the severity, but not the prevalence, of cognitive symptoms.

CONCLUSIONS

The results highlight the complexity of pharmacological management in FM and raise concerns about the inappropriate use of ineffective or counterproductive drug interactions affecting patients' mental health. They underscore the need for multidisciplinary and personalized strategies that include close and careful monitoring, as well as the simultaneous use of non-pharmacological treatments that have demonstrated evidence in improving quality of life without negatively affecting mental health, such as patient education, psychological therapy, physiotherapy, and mindfulness.

Opioids and Cannabinoids in Neurology Practice

OBJECTIVE

Opioid and cannabinoid therapies for chronic pain conditions including neuropathic pain are controversial. Understanding patient and prescribing factors contributing to risks and implementing risk mitigation strategies optimizes outcomes.

LATEST DEVELOPMENTS

The ongoing transformation from a biomedical model of pain care toward a biopsychosocial model has been accompanied by a shift away from opioid therapy for pain, in particular for chronic pain. Opioid overdose deaths and opioid use disorder have greatly increased in the last several decades, initially because of increases in opioid prescribing and more recently associated with illicit drug use, in particular fentanyl derivatives. Opioid risk mitigation strategies may reduce risks related to opioid prescribing and tapering or discontinuation. Opioid therapy guidelines from the Centers for Disease Control and Prevention have become the consensus best practice for opioid therapy. Regulatory agencies and licensing medical boards have implemented restrictions and other mandates regarding opioid therapy. Meanwhile, interest in and use of cannabinoids for chronic pain has grown in the United States.

ESSENTIAL POINTS

Opioid therapy is generally not recommended for the chronic treatment of neuropathic pain conditions. Opioids may be considered for temporary use in patients with severe pain related to selected neuropathic pain conditions (such as postherpetic neuralgia), and only as part of a multimodal treatment regimen. Opioid risk mitigation strategies include careful patient selection and evaluation, patient education and informed consent, querying the state prescription drug monitoring programs, urine drug testing, and issuance of naloxone as potential rescue medication. Close follow-up when initiating or adjusting opioid therapy and frequent reevaluation during long-term opioid therapy is required. There is evidence for the efficacy of cannabinoids for neuropathic pain, with meaningful response rates in select patient populations.

Sensory Profiles Predict Symptoms of Central Sensitization in Low Back Pain: A Predictive Model Research Study

Background: Acute low back pain has a high prevalence, and when persisting into chronicity, it results in enormous socio-economic consequences. Sensory preferences may be key factors in predicting central sensitization as the main mechanism of nociplastic pain and chronicity. Objectives: Build a model to predict central sensitization symptoms using sensory profiles based on the PROGRESS framework. Methods: A Prognostic Model Research study was carried out to predict central sensitization symptoms at 12 weeks, using baseline sensory profiles, based on 114 patients with acute low back pain. Independent variables were sensory profiles, state and trait anxiety, age, duration, pain severity, depressive symptoms, and pain catastrophizing. Results: This model, based on continuous data, significantly predicts central sensitization symptoms at 12 weeks. It contains two significantly contributing variables: sensory profile Sensory Sensitive (unstandardized B-value = 0.42; p = 0.01) and trait anxiety (unstandardized B-value = 0.53; p ≤ 0.001). The model has a predictive value of R2 = 0.38. Conclusions: This model significantly predicts central sensitization symptoms based on sensory profile Sensory Sensitive and trait anxiety. This model may be a useful tool to intervene in a bottom-up and top-down approaches to prevent chronicity in clinical practice, including individual sensory preferences and behavioral responses to sensory stimulation in rehabilitation strategies.

Relational vulnerability in motherhood-an existential perspective on pain and exhaustion among women

Introduction

Stress-related ill-health like pain and exhaustion are demanding public health problems in Europe. In Sweden, women are particularly at risk to develop stress-related ill-health during a period in life that coincides with child-rearing years. When entering motherhood, Swedish women's sick leave substantially increases. Yet, motherhood is rarely acknowledged in clinical encounters concerning pain and exhaustion although women suffer from these ailments more often than men. To incorporate motherhood as an existential dimension of health in the care of women living with pain and exhaustion might alleviate women's suffering. But knowledge on women's experiences of motherhood and health is scarce. Therefore, the aim of the study is to reach a deeper understanding of how women suffering from long-lasting pain and exhaustion experience their health in relation to motherhood.

Methods

Ricoeur's interpretation theory has been applied to analyze 27 phenomenological interviews with 14 mothers suffering from long-lasting pain and exhaustion.

Results

These women's experiences shed light on how closely motherhood is interwoven with the experience of their health and suffering: The women's suffering seems to be rooted in a relational vulnerability that has been uncovered during motherhood. Further, the women suffer from a burden of difficult life experiences and inner conflicts. Reconciliation with life is possible when women find an existential shelter, which offers ways to relate to their suffering making the own suffering more bearable.

Effectiveness of craniosacral therapy, Bowen therapy, static touch and standard exercise program on sleep quality in fibromyalgia syndrome: A randomized controlled trial

BACKGROUND

Sleep disturbance is commonly seen in fibromyalgia syndrome (FMS); however, high quality studies involving manual therapies that target FMS-linked poor sleep quality are lacking for the Indian population.

OBJECTIVE

Craniosacral therapy (CST), Bowen therapy and exercises have been found to influence the autonomic nervous system, which plays a crucial role in sleep physiology. Given the paucity of evidence concerning these effects in individuals with FMS, our study tests the effectiveness of CST, Bowen therapy and a standard exercise program against static touch (the manual placebo group) on sleep quality in FMS.

DESIGN, SETTING, PARTICIPANTS AND INTERVENTION

A placebo-controlled randomized trial was conducted on 132 FMS participants with poor sleep at a hospital in Bangalore. The participants were randomly allocated to one of the four study groups, including CST, Bowen therapy, standard exercise program, and a manual placebo control group that received static touch. CST, Bowen therapy and static touch treatments were administered in once-weekly 45-minute sessions for 12 weeks; the standard exercise group received weekly supervised exercises for 6 weeks with home exercises until 12 weeks. After 12 weeks, all study participants performed the standard exercises at home for another 12 weeks.

MAIN OUTCOME MEASURES

Sleep quality, pressure pain threshold (PPT), quality of life and fibromyalgia impact, physical function, fatigue, pain catastrophizing, kinesiophobia, and positive-negative affect were recorded at baseline, and at weeks 12 and 24 of the intervention.

RESULTS

At the end of 12 weeks, the sleep quality improved significantly in the CST group (P = 0.037) and Bowen therapy group (P = 0.023), and the PPT improved significantly in the Bowen therapy group (P = 0.002) and the standard exercise group (P < 0.001), compared to the static touch group. These improvements were maintained at 24 weeks. No between-group differences were observed for other secondary outcomes.

CONCLUSION

CST and Bowen therapy improved sleep quality, and Bowen therapy and standard exercises improved pain threshold in the short term. These improvements were retained within the groups in the long term by adding exercises. CST and Bowen therapy are treatment options to improve sleep and reduce pain in FMS.

TRIAL REGISTRATION NUMBER

Registered at Clinical Trials Registry of India with the number of CTRI/2020/04/024551. Please cite this article as: Ughreja RA, Venkatesan P, Gopalakrishna DB, Singh YP, Lakshmi VR. Effectiveness of craniosacral therapy, Bowen therapy, static touch and standard exercise program on sleep quality in fibromyalgia syndrome: a randomized controlled trial. J Integr Med. 2024; 22(4): 474-484.

Astrocyte regulation of extracellular space parameters across the sleep-wake cycle

Multiple subfields of neuroscience research are beginning to incorporate astrocytes into current frameworks of understanding overall brain physiology, neuronal circuitry, and disease etiology that underlie sleep and sleep-related disorders. Astrocytes have emerged as a dynamic regulator of neuronal activity through control of extracellular space (ECS) volume and composition, both of which can vary dramatically during different levels of sleep and arousal. Astrocytes are also an attractive target of sleep research due to their prominent role in the glymphatic system, a method by which toxic metabolites generated during wakefulness are cleared away. In this review we assess the literature surrounding glial influences on fluctuations in ECS volume and composition across the sleep-wake cycle. We also examine mechanisms of astrocyte volume regulation in glymphatic solute clearance and their role in sleep and wake states. Overall, findings highlight the importance of astrocytes in sleep and sleep research.

Burden of disease, pain catastrophizing, and central sensitization in relation to work-related issues in young spondyloarthritis patients

Introduction

Spondyloarthritis (SpA) is a common rheumatic inflammatory disease and can impact patients' work productivity. We aimed to evaluate the impact of pain catastrophizing and central sensitization on work outcomes in young SpA patients and determine the predictive factors of work productivity loss.

Material and methods

We performed a cross-sectional study over 6 months. We included patients aged between 18 and 50 years old, diagnosed with axial or peripheral SpA. Pain catastrophizing and central sensitization were assessed using the Pain Catastrophizing Scale (PCS) and Central Sensitization Inventory (CSI) questionnaire, respectively. Impact of SpA on work productivity and activity impairment during and outside of work was measured with the Work Productivity and Activity Impairment Questionnaire (WPAI: Spondyloarthritis).

Results

A total of 72 patients were enrolled, with a median age of 39 years (28.3-46), 65.3% men, and 54.4% working patients. Median scores of activity impairment outside of work, and work productivity loss were 50% (40-70), and 50% (40-60), respectively. Median absenteeism and presenteeism scores were 0% (IQR 0-7), and 100% (IQR 86.5-100), respectively. Regarding work-related outcomes: activity impairment was positively correlated with CSI and PCS; presenteeism was significantly associated with male sex (p = 0.009); and work productivity loss was positively associated with anxiety, depression, and poor quality of life. Multivariate regression analysis identified predictive factors of work productivity loss: male sex, poor quality of life, and prolonged morning stiffness.

Conclusions

Assessment of the impact of pain catastrophizing and central sensitization on work-related outcomes in patients with SpA is important to understand the burden of illness and to identify early those in need of interventions in clinical practice.

Beneficial Effects of Photoperiod Lengthening on Sleep Characteristics and Mechanical Hyperalgesia in Injured Rats

Sleep and muscle injury-related pain are in negative relationship, and sleep extension may be a favorable countermeasure. In response to muscle injury, an adaptive sleep response has been described in rats, characterized by an increase in total sleep time (TST) and nonrapid eye movement (NREM) sleep. This study examined the effects of photoperiod lengthening (a model of sleep prolongation in rats) on the sleep characteristics of muscle-injured rats and whether this lengthening could benefit injury-induced mechanical hyperalgesia using the Von Frey test. Switching from the conventional 12:12 light/dark (LD) photoperiod (light on: 08:00-20:00) to LD 16:8 (light extended to 24:00) gives rats an extra window of sleep. Our results show higher TST and NREM sleep times in LD 16:8 versus LD 12:12 injured rats during 4 h of light lengthening for 7 d postinjury, showing the efficiency of photoperiod lengthening to increase sleep time in injured rats. In addition, a cumulative effect with the adaptive sleep response to muscle injury occurred with higher TST and NREM sleep times in LD 16:8 injured versus noninjured rats during the dark period, reflecting the high need for sleep after the injury. Greater stability and higher relative delta power of NREM sleep during the extended light period were also observed in injured rats. Finally, the extended photoperiod limits the muscle injury-induced mechanical hyperalgesia for 13 d and allows faster recovery of the baseline mechanical threshold. This is associated with reduced pro-inflammatory cytokines levels in the hippocampus, a brain structure involved in pain processing.

Poor Subjective Sleep Quality Predicts Symptoms in Irritable Bowel Syndrome Using the Experience Sampling Method

INTRODUCTION

Sleep quality may affect symptom experience in irritable bowel syndrome (IBS). Our aim was to investigate the relationship between sleep quality and gastrointestinal (GI) symptoms using actigraphy and the experience sampling method.

METHODS

Patients with IBS were recruited from a tertiary Neurogastroenterology clinic and the community. GI symptoms and mood were recorded on a smartphone application, 10 times per day, over 7 consecutive days. Subjective sleep quality was recorded every morning to reflect the night before. Objective measures of sleep quality were estimated from wrist-worn actigraphy. Cross-lagged structural equation models were built to assess the directionality of sleep-symptom relationships over time.

RESULTS

Eighty patients with IBS completed the study (mean age: 37 years [range 20-68], 89% female, 78% community). Approximately 66% had a Pittsburgh Sleep Quality Index score ≥ 8, indicating a clinically significant sleep disturbance. Approximately 82% (95% CI: 72-90) screened positive for a sleep disorder, most commonly insomnia. In cross-lagged analysis, poor subjective sleep quality predicted next-day abdominal pain (0.036 < P < 0.040) and lower GI symptoms (0.030 < P < 0.032), but not vice versa. No significant relationship with GI symptoms was found for any objective sleep measure using actigraphy.

DISCUSSION

Poor subjective sleep quality was associated with higher next-day lower GI symptom levels, but not vice versa. Objective sleep measures did not predict next-day abdominal symptoms, potentially supporting the conclusion that it is the perception of sleep quality that is most influential. This study may be used to guide future research into the effect of sleep interventions on GI symptoms.

Effects of sleep quality on pain, cognitive factors, central sensitization, and quality of life in patients with chronic low back pain

BACKGROUND

Sleep quality in patients with chronic low back pain (CLBP) may affect quality of life (QoL), possibly due to worsening pain, central sensitization (CS), and cognitive factors. However, causal relationship among the factors has not been confirmed yet.

OBJECTIVE

The purpose of this study was to test the hypothesis that sleep quality in patients with CLBP is attributable to pain, cognitive factors, and CS, and influences QoL, by structural covariance analysis.

METHODS

This is a cross-sectional study. Participants were recruited from six health care facilities and 101 patients with CLBP were included. Structural covariance analysis assessed the fit of data to the model using goodness of fit index (GFI), adjusted goodness of fit index (AGFI), comparative fit index (CFI), and mean squared approximation error (RMSEA).

RESULTS

The structural covariance analysis showed that the goodness-of-fit indices were high (GFI = 0.993, AGFI = 0.964, CFI = 1.00, RMSEA < 0.01). Sleep quality was not directly influenced by QoL but rather by CS and cognitive factors.

CONCLUSION

This study suggests that sleep quality in patients with CLBP is indirectly mediated through multiple pathways, including cognitive factors and CS, which may influence QoL.

Lifestyle factors and psychological factors are associated with central pain processing in service members with persistent low-back pain: A cross-sectional exploratory study

Persistent low-back pain (LBP) is highly prevalent in the military. Altered central pain processing is one of the mechanisms found to underlie persistent LBP. Our aim was to explore which factors are associated with altered pain processing in Dutch service members with persistent LBP. This knowledge may guide clinicians in what factors to address in the treatment of dysfunctional pain processing in service members with persistent LBP. Twenty-one service members with persistent LBP (mean age 34.0 years, 18 males) were included in this cross-sectional exploratory study. Participants completed questionnaires regarding lifestyle and psychological factors. Altered central pain processing was measured by temporal summation of pain to examine the function of the pain facilitatory system and by conditioned pain modulation to examine the pain inhibitory function. Univariable and multivariable linear regression analyses were performed. A higher local temporal summation of pain was associated with a longer sitting time, a higher level of physical activity and a higher level of pain catastrophizing. A higher local conditioned pain modulation was associated with a higher level of pain catastrophizing, anxiety and depression symptoms, and with a lower sleep quality. A higher remote conditioned pain modulation effect was associated with a higher level of physical activity, a higher body mass index and a shorter sitting time. This study succeeded in identifying lifestyle and psychological factors associated with altered pain processing in service members with persistent LBP. Prospective studies are needed to examine causality in these relationships.

The relation of psychological status and type D personality with central sensitization in knee osteoarthritis: everything is in your mind!

To evaluate the relation of psychosocial parameters and type D personality with central sensitization in knee osteoarthritis (OA). The study included 126 patients with knee OA according to the American College of Rheumatology criteria. Sociodemographic variables (age, gender, education, marital status, annual income), alcohol consumption/smoking, body mass index, comorbidities, and duration of symptoms were noted. Radiographic evaluation was performed according to the Kellgren-Lawrence grading system. The Western Ontario and McMaster Universities Osteoarthritis Index was used for clinical evaluation. Type D personality, negative affectivity, and social inhibition were evaluated using the type D Scale-14 (DS14). Central sensitization was assessed by the central sensitization inventory (CSI), while psychological status, quality of life, and sleep were assessed by the Hospital Anxiety and Depression Scale (HADS), an abbreviated version of the World Health Organization Quality of Life Instrument (WHOQOL-BREF), and the Jenkins Sleep Evaluation Scale (JSS), respectively. The effect of type D personality on study parameters including central sensitization, as well as the risk factors for the development of central sensitization were assessed by regression analyses. Patients with type D personality had higher CSI, HADS scores and lower WHOQOL-BREF scores for psychological health, social relationship, environment and general quality of life. Linear regression analysis showed that the DS14 total score has a significant positive relation with CSI (β = 0.4, p < 0.05), HADS-depression (β = 0.4, p < 0.05), HADS-anxiety (β = 0.5, p < 0.05), and HADS-total scores (β = 0.5, p < 0.05). It also had a significant negative effect on all domains of WHOQOL-BREF (p < 0.05 for all). Logistic regression analysis revealed that JSS [Odds ratio (OR) 0.83, 95% CI 0.73-0.94; p = 0.003] and negative affectivity (OR 0.78, 95% CI 0.65-0.94; p = 0.008) were independent risk factors for the development of central sensitization in knee OA. Type D personality has an impact on quality of life, central sensitization, and psychological health, with negative affectivity and sleep impairment serving as independent risk factors for central sensitization. While managing patients with knee OA, these intimate relationships should be taken into consideration.

Associations between Combined Psychological and Lifestyle Factors with Pain Intensity and/or Disability in Patients with Chronic Low Back Pain: A Cross-Sectional Study

Chronic low back pain (CLBP) is common in primary care, causing disability and economic burden globally. We aimed to compare socio-demographic, health, lifestyle, and psychological factors in people with and without CLBP and correlate them with clinical outcomes in people with CLBP. A total of 253 volunteers with and 116 without CLBP provided sociodemographic information, daily habits, medical history, subjective sleep complaints (Penn State Sleep Questionnaire), low back pain intensity, and disability (Quebec Back Pain Disability Scale), as well as the Zung Self-Rating Scale for self-assessment of depression and Self-Rating Anxiety Scale. CLBP diagnosis was linked with female gender and older age, as well as a higher level of sleep complaints such as sleepiness, OSA and insomnia symptoms, and a higher prevalence of moderate to severe depressive symptoms. The combination of moderate to severe depressive symptoms with obstructive sleep apnea or insomnia symptoms was the most important predictive factor for functional disability in CBLP patients (OR 13.686, 95% CI 4.581-40.885; p < 0.001). In conclusion, depressive symptoms and subjective sleep complaints appear to relate to greater CLBP intensity and/or CLBP-related disability in people with CLBP. A holistic approach is crucial for treating chronic CLBP patients, including psychological and sleep issue assessment and management, to improve their quality of life.

Are physical therapy interventions effective in improving sleep in people with chronic pain? A systematic review and multivariate meta-analysis

Chronic pain exerts an enormous personal and economic burden, with sleep disturbances being one of the most reported problems by adults with chronic pain. The aim of this study was to analyse whether different physical therapy interventions could lead to improvements in sleep quality and pain intensity in individuals with chronic pain, as well as if there is any association. A systematic review and a univariate and multivariate meta-analysis were carried out according to the PRISMA guidelines. A search in PubMed, Scopus and Web of Science databases was performed. Six randomised controlled trials were included in the review and four of them were included in the meta-analysis; all of them with a moderate to high methodological quality. Data from adult participants with chronic pain after different physical therapy interventions was extracted. For the meta-analysis, the Insomnia Severity Index and the Numerical Rating Scale were considered. Results from the qualitative and quantitative analysis showed that most of the physical therapy interventions included had higher improvements in the intervention group than in the control group, although the effect size was not statistically significant (univariate for sleep quality: -0.08 [-0.34, 0.18], p = 0.46; univariate for pain intensity: -0.47 [-1.24, 0.30], p = 0.18; multivariate for both outcomes: -0.27). More studies are still needed to determine which physical therapy interventions are effective to improve sleep in people with chronic pain and if there are patients with specific characteristics who may benefit more than others.

Intrathecal Injection of Botulinum Toxin Type A has an Analgesic Effect in Male Rats CCI Model by Inhibiting the Activation of Spinal P2X4R

Purinergic receptor P2X4 (P2X4R) plays an essential role in neuropathic pain. However, the specific mechanism needs to be clarified. Botulinum toxin type A is a neurotoxin produced by Clostridium botulinum type A. This study found that intrathecal injection of botulinum toxin type A produced an excellent analgesic effect in a rat model of chronic constriction sciatic nerve injury and inhibited the activation of P2X4R, microglia, and astrocytes. The administration of a P2X4R activator can up-regulate the expression of P2X4R and eliminate the analgesic effect of intrathecal injection of botulinum toxin type A. In addition, we found that microglia and astrocytes in the spinal cord of rats injected with botulinum toxin type A were reactivated after administration of the P2X4R activator. Our results suggest that intrathecal injection of botulinum toxin type A has an analgesic effect in a rat model of chronic constriction sciatic nerve injury by inhibiting the activation of P2X4R in the spinal cord.

The Challenge of Fibromyalgia Efficacy of Hypnosis in Alleviating the Invisible Pain: A Narrative Review

Fibromyalgia syndrome (FMS) is a multifaceted and incapacitating functional pain syndrome characterized by continuous, severe, widespread musculoskeletal pain. FMS is associated with other symptoms such as fatigue, nonrestorative sleep, cognitive/emotional dysfunction, and diminished health-related quality of life. The pathogenesis of FMS is still not fully understood, but an increasing amount of evidence supports the link between childhood/adulthood emotional, physical, sexual abuse or neglect and the development of FMS. Managing and treating FMS patients can be challenging because the syndrome is refractory to most treatments. However, psychological interventions, particularly hypnotherapy, have been shown to be effective in the cognitive modulation of fibromyalgic pain. FMS patients may benefit from hypnotherapy alone or in combination with standard medical therapy. Symptom-oriented hypnosis aims to reduce pain, fatigue, sleep problems, anxiety, and depression, while hypnotherapy focuses on resolving emotional conflicts and unresolved traumas associated with FMS. In conclusion, hypnosis may be a useful and safe adjunct tool for managing chronic pain and dysfunctional symptoms in challenging fibromyalgic patients.

Patients with neuropathic pain from lumbosacral radiculopathy demonstrate similar pressure pain thresholds and conditioned pain modulation to those with fibromyalgia

OBJECTIVE

The purpose of the study was to evaluate pain thresholds, impairment of the endogenous pain modulatory system, and self-reported cognitive-emotional and central sensitization-related symptoms among three subject groups: a rarely studied patient cohort with neuropathic pain from lumbosacral radiculopathy (NPLSR), patients with fibromyalgia (FM) and healthy controls (HC).

METHODS

Patient-reported pain-related symptomology was evaluated with psychometricallyvalidated questionnaires. Pressure pain threshold (PPT), heat pain threshold (HPT), and cold pain threshold (CPT) were assessed in the low back and contralateral forearm. Conditioned pain modulation (CPM) was evaluated with a recently introduced methodology that accounts for a standard error of measurement.

RESULTS

Compared to the HC subjects, the FM and NPLSR subjects had significantly lower pain thresholds and more CPM impairment. No significant differences in PPT and CPM were observed between the FM and NPLSR groups. Significant group differences were found in self-reported symptoms of depression, anxiety, stress, and central sensitization. Self-reported symptom severity increased in a stair-step fashion, with the HC group scoring lowest and FM group scoring highest.

CONCLUSION

The NPLSR group manifested CPM dysfunction and pressure hyperalgesia at similar levels to the FM group, indicating that these two chronic pain syndromes, likely based on different pathophysiological mechanisms, in fact share some common pain processing features. However, though both patient groups demonstrated similarities in pain processing, self-reported cognitive-emotional and central sensitization-related symptom severity was significantly higher in the FM cohort, which distinguished them from the chronic NPLSR cohort.

The interplay between symptoms of insomnia and pain in people with osteoarthritis: A narrative review of the current evidence

Osteoarthritis (OA) is a leading cause of disability worldwide and clinical pain is the major symptom of OA. This clinical OA-related pain is firmly associated with symptoms of insomnia, which are reported in up to 81% of people with OA. Since understanding the association between both symptoms is critical for their appropriate management, this narrative review synthesizes the existing evidence in people with OA on i) the mechanisms underlying the association between insomnia symptoms and clinical OA-related pain, and ii) the effectiveness of conservative non-pharmacological treatments on insomnia symptoms and clinical OA-related pain. The evidence available identifies depressive symptoms, pain catastrophizing and pain self-efficacy as mechanisms partially explaining the cross-sectional association between insomnia symptoms and pain in people with OA. Furthermore, in comparison to treatments without a specific insomnia intervention, the ones including an insomnia intervention appear more effective for improving insomnia symptoms, but not for reducing clinical OA-related pain. However, at a within-person level, treatment-related positive effects on insomnia symptoms are associated with a long-term pain reduction. Future longitudinal prospective studies offering fundamental insights into neurobiological and psychosocial mechanisms explaining the association between insomnia symptoms and clinical OA-related pain will enable the development of effective treatments targeting both symptoms.

The (cost-)effectiveness of combined lifestyle interventions for people with persistent low-back pain who are overweight or obese: A systematic review

INTRODUCTION

Lifestyle factors are expected to contribute to the persistence and burden of low-back pain (LBP). However, there are no systematic reviews on the (cost-)effectiveness of combined lifestyle interventions for overweight or obese people with LBP.

AIM

To assess whether combined lifestyle interventions are (cost-)effective for people with persistent LBP who are overweight or obese, based on a systematic review.

DESIGN

Systematic review METHOD: PubMed, Cochrane, Embase, CINAHL, PsycINFO and the Wiley/Cochrane Library were searched from database inception till January 6^th 2023. Two independent reviewers performed study selection, data-extraction and risk of bias scoring using the Cochrane RoB tool 2 and/or the Consensus Health Economic Criteria list. GRADE was used to assess the level of certainty of the evidence.

RESULTS

In total 2510 records were screened, and 4 studies on 3 original RCTs with 216 participants were included. Low certainty evidence (1 study) showed that combined lifestyle interventions were not superior to usual care for physical functioning, pain and lifestyle outcomes. Compared to usual care, moderate certainty evidence showed that healthcare (-$292, 95%CI: 872; -33), medication (-$30, 95% CI -65; -4) and absenteeism costs (-$1000, 95%CI: 3573; -210) were lower for the combined lifestyle interventions.

CONCLUSION

There is low certainty evidence from 3 studies with predominantly small sample sizes, short follow-up and low intervention adherence that combined lifestyle interventions are not superior to physical functioning, pain and lifestyle outcomes compared to usual care, but are likely to be cost-effective.

Biopsychosocial factors should be considered when evaluating central sensitization in axial spondyloarthritis

To identify the determinants of central sensitization (CS) in patients with axial spondyloarthritis (axSpA). Central Sensitization Inventory (CSI) was used to determine CS frequency. Disease-related variables including Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Disease Activity Score (ASDAS-CRP/-ESR), Maastricht Ankylosing Spondylitis Enthesitis Score (MASES), Bath Ankylosing Spondylitis Functional Index (BASFI), Ankylosing Spondylitis Quality of Life Questionnaire (ASQoL) and Numeric Rating Scale (NRS)GLOBAL were assessed. Biopsychosocial variables were evaluated by the Multidimensional Scale of Perceived Social Support (MSPSS), Brief Illness Perception Questionnaire (B-IPQ), Hospital Anxiety and Depression Scale (HADS) and subscales for Anxiety (HADS-A) and Depression (HADS-D), and Jenkins Sleep Evaluation Scale (JSS). To determine the predictors of the development and severity of CS, multiple linear and logistic regression analyses were performed. The frequency of CS was 57.4% in the study population (n = 108). CSI score was correlated with the duration of morning stiffness, BASDAI, ASDAS-CRP, ASDAS-ESR, NRSGLOBAL, BASFI, MASES, ASOoL, JSS, HADS, and B-IPQ total scores (ρ ranged from 0.510 to 0.853). Multiple regression analysis indicated that BASDAI (OR: 10.44, 95% CI: 2.65-41.09), MASES (OR: 2.47, 95% CI: 1.09-5.56) and HADS-A (OR: 1.62, 95% CI: 1.11-2.37) were independent predictors of the development of CS. Additionally, higher NRSGLOBAL, JSS, HADS-D, and HADS-A scores appeared to determine the severity of CS. This study confirms that worse disease activity, more enthesal involvement, and anxiety independently predict the development of CS. Additionally, higher patient-perceived disease activity, sleep impairment and poor mental health significantly contribute to the severity of CS.

Central metabolites and peripheral parameters associated neuroinflammation in fibromyalgia patients: A preliminary study

To identify central metabolites and peripheral measures associated with neuroinflammation in fibromyalgia (FM), we scanned [11C]-(R)-PK11195 positron emission tomography and magnetic resonance spectroscopy in FM patients. We measured associations between neurometabolite levels measured by magnetic resonance spectroscopy and the extent of neuroinflammation inferred by the distribution volume ratios of [11C]-(R)-PK11195 positron emission tomography in 12 FM patients and 13 healthy controls. We also examined the associations between peripheral parameters, such as creatinine and C-reactive protein, and neuroinflammation. In FM patients, we found negative correlations between neuroinflammation and the creatine (Cr)/total creatine (tCr; Cr + phosphocreatine) ratios in the right (r = -0.708, P = .015) and left thalamus (r = -0.718, P = .008). In FM patients, negative correlations were apparent between neuroinflammation and the glutamate/tCr ratio in the right insula (r = -0.746, P = .005). In FM patients, we found negative correlations between neuroinflammation in the left thalamus (r = -0.601, P = .039) and left insula (r = -0.598, P = .040) and the blood creatinine levels. Additionally, we found significant correlations of other peripheral measures with neuroinflammation in FM patients. Our results suggest that both central metabolites, such as Cr and glutamate, and peripheral creatinine and other parameters are associated with neuroinflammation in patients with FM.

High intensity training improves symptoms of central sensitization at six-month follow-up in persons with chronic nonspecific low back pain: Secondary analysis of a randomized controlled trial

BACKGROUND

High intensity training (HIT) improves disability and physical fitness in persons with chronic nonspecific low back pain (CNSLBP). However, it remains unclear if HIT affects pain processing and psychosocial factors.

OBJECTIVE

To evaluate 1) the effects of HIT on symptoms of central sensitization and perceived stress and 2) the relationship of symptoms of central sensitization and perceived stress with therapy success, at six-month follow-up, in persons with CNSLBP.

METHODS

This is a secondary analysis of a previously published randomized controlled trial. Persons with CNSLBP (n = 51, age=43.6y) completed the Central Sensitization Inventory (CSI) and Perceived Stress Scale (PSS) at baseline (PRE) and six months after 12-week of HIT consisting of concurrent exercise therapy (FU). Two groups were formed based on CSI scores (low-CSI/high-CSI). First, linear mixed models were fitted for each outcome, with time and groups as covariates. Multiple comparisons were executed to evaluate group (baseline), time (within-group), and interaction (between-group) effects. Second, correlation and regression analyses were performed to evaluate if baseline and changes in CSI/PSS scores were related to therapy success, operationalized as improvements on disability (Modified Oswestry Disability Index), and pain intensity (Numeric Pain Rating Scale).

RESULTS

Total sample analyses showed a decrease in both CSI and PSS. Within-group analyses showed a decrease of CSI only in the high-CSI group and a decrease of PSS only in the low-CSI group. Between-group analyses showed a pronounced decrease favouring high-CSI (mean difference: 7.9; 95%CI: 2.1, 12.7) and no differences in PSS (mean difference: 0.1; 95%CI: -3.0, 3.2). CSI, but not PSS, was weakly related to therapy success.

CONCLUSION

HIT improves symptoms of central sensitization in persons with CNSLBP. This effect is the largest in persons with clinically relevant baseline CSI scores. HIT also decreases perceived stress.

The Biology of Stress Intolerance in Patients with Chronic Pain—State of the Art and Future Directions

Stress has been consistently linked to negative impacts on physical and mental health. More specifically, patients with chronic pain experience stress intolerance, which is an exacerbation or occurrence of symptoms in response to any type of stress. The pathophysiological mechanisms underlying this phenomenon remain unsolved. In this state-of-the-art paper, we summarised the role of the autonomic nervous system (ANS) and hypothalamus-pituitary-adrenal (HPA) axis, the two major stress response systems in stress intolerance. We provided insights into such mechanisms based on evidence from clinical studies in both patients with chronic pain, showing dysregulated stress systems, and healthy controls supported by preclinical studies, highlighting the link between these systems and symptoms of stress intolerance. Furthermore, we explored the possible regulating role for (epi)genetic mechanisms influencing the ANS and HPA axis. The link between stress and chronic pain has become an important area of research as it has the potential to inform the development of interventions to improve the quality of life for individuals living with chronic pain. As stress has become a prevalent concern in modern society, understanding the connection between stress, HPA axis, ANS, and chronic health conditions such as chronic pain is crucial to improve public health and well-being.

The Putative Role of Neuroinflammation in the Interaction between Traumatic Brain Injuries, Sleep, Pain and Other Neuropsychiatric Outcomes: A State-of-the-Art Review

Sleep disturbances are widely prevalent following a traumatic brain injury (TBI) and have the potential to contribute to numerous post-traumatic physiological, psychological, and cognitive difficulties developing chronically, including chronic pain. An important pathophysiological mechanism involved in the recovery of TBI is neuroinflammation, which leads to many downstream consequences. While neuroinflammation is a process that can be both beneficial and detrimental to individuals' recovery after sustaining a TBI, recent evidence suggests that neuroinflammation may worsen outcomes in traumatically injured patients, as well as exacerbate the deleterious consequences of sleep disturbances. Additionally, a bidirectional relationship between neuroinflammation and sleep has been described, where neuroinflammation plays a role in sleep regulation and, in turn, poor sleep promotes neuroinflammation. Given the complexity of this interplay, this review aims to clarify the role of neuroinflammation in the relationship between sleep and TBI, with an emphasis on long-term outcomes such as pain, mood disorders, cognitive dysfunctions, and elevated risk of Alzheimer's disease and dementia. In addition, some management strategies and novel treatment targeting sleep and neuroinflammation will be discussed in order to establish an effective approach to mitigate long-term outcomes after TBI.

Effectiveness of aquatic therapy on sleep in persons with fibromyalgia. A meta-analysis

CONTEXT

Fibromyalgia syndrome (FMS) is a chronic musculoskeletal condition characterized by persistent, widespread pain, myofascial tenderness, negative affect, fatigue, memory problems and sleep disturbances.

OBJECTIVE

To summarize the evidence of the effects of aquatic therapy on sleep quality in patients with FMS.

METHODS

This systematic review and meta-analysis was performed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols 2020 (PRISMA) guidelines and registered in the International Prospective Register of Systematic Reviews (PROSPERO), whit the registration number CRD42021249982. Cochrane library, Medline (PubMed), Science Direct Web of Science (WOS), Scopus, and PEDro were searched from inception until September 2021. The search included only randomized clinical trials.

RESULTS

Of the 7711 studies identified in the initial search, a total of 7 trials (361 participants) satisfied the eligibility criteria. Finally, a meta-analysis was conducted with 6 studies (311 participants). The overall pooled effect favored aquatic therapy interventions in improving sleep quality in patients with FMS (pooled MD, -2.05; 95% CI, -4.35 to 0.25).

CONCLUSIONS

The results of this systematic review and meta-analysis provide evidence that aquatic therapy improved sleep quality in patients with FMS. This study highlights the importance of aquatic therapy for sleep. Nonetheless, although an aquatic therapy intervention may represent a good option to improve sleep, given the low number of studies the evidence should be taken with caution.

Towards precision pain medicine for pain after cancer: the Cancer Pain Phenotyping Network multidisciplinary international guidelines for pain phenotyping using nociplastic pain criteria

Pain after cancer remains underestimated and undertreated. Precision medicine is a recent concept that refers to the ability to classify patients into subgroups that differ in their susceptibility to, biology, or prognosis of a particular disease, or in their response to a specific treatment, and thus to tailor treatment to the individual patient characteristics. Applying this to pain after cancer, the ability to classify post-cancer pain into the three major pain phenotypes (i.e. nociceptive, neuropathic, and nociplastic pain) and tailor pain treatment accordingly, is an emerging issue. This is especially relevant because available evidence suggests that nociplastic pain is present in an important subgroup of those patients experiencing post-cancer pain. The 2021 International Association for the Study of Pain (IASP) clinical criteria and grading system for nociplastic pain account for the need to identify and correctly classify patients according to the pain phenotype early in their treatment. These criteria are an important step towards precision pain medicine with great potential for the field of clinical oncology. Within this framework, the Cancer Pain Phenotyping (CANPPHE) Network, an international and interdisciplinary group of oncology clinicians and researchers from seven countries, applied the 2021 IASP clinical criteria for nociplastic pain to the growing population of those experiencing post-cancer pain. A manual is provided to allow clinicians to differentiate between predominant nociceptive, neuropathic, or nociplastic pain after cancer. A seven-step diagnostic approach is presented and illustrated using cases to enhance understanding and encourage effective implementation of this approach in clinical practice.

Clinical and functional impact of central sensitization on patients with familial Mediterranean fever: a cross-sectional study

This study aimed to investigate the frequency of CS and its clinical and functional effects on familial Mediterranean fever (FMF). A hundred FMF patients were included in this study. The presence of CS was investigated by the central sensitization inventory (CSI). In addition to the detailed clinical features of patients and genetic mutations, quality of life, disability, sleep disorders, depression, anxiety, and fibromyalgia frequency were examined to evaluate the negative effects of CS on the individual. Patients were divided into groups according to the presence and severity of CS, and their results were compared. Correlation and multivariate regression analysis were performed to investigate the association of CS  with selected demographic and clinical parameters. The mean CSI was 37.72 (SD: 19.35), and thirty-eight (38%) patients had CS. Sacroiliitis occurred in 11 patients (11%), amyloidosis in 3 (3%), and erysipelas-like erythema in 11 (11%). The most prevalent genetic mutation was M694/any compound heterogeneous (35.7%), followed by M69V homogeneous (30%). Regarding comparing the patients with and without CS, the number of attacks, disease activity, daily colchicine dose, and all investigated comorbidities were significantly higher in the patients with CS (p < 0.05). In regression analysis, gender, colchicine dose and sleep disturbance were detected as related parameters with CS (OR (95% CI): 6.05 (1.39; 26.32), p: 0.017, OR (95% CI): 6.69 (1.65; 27.18), p: 0.008, OR (95% CI): 1.35 (1.35; 1.59), p: 0.001, respectively). Concomitant pain sensitization appears to be related to FMF patients' clinical and functional characteristics. These results suggest taking into consideration CS in the management of FMF patients.

Associations between early sleep-disordered breathing following moderate-to-severe traumatic brain injury and long-term chronic pain status: a Traumatic Brain Injury Model Systems study

STUDY OBJECTIVES

To explore the relationship between polysomnography-derived respiratory indices and chronic pain status among individuals following traumatic brain injury (TBI).

METHODS

Participants (n = 66) with moderate to severe TBI underwent polysomnography during inpatient acute rehabilitation and their chronic pain status was assessed at 1- to 2-year follow-up as part of the TBI Model Systems Pain Collaborative Study. Pairwise comparisons across pain cohorts (ie, chronic pain, no history of pain) were made to explore differences on polysomnography indices.

RESULTS

Among our total sample, approximately three-quarters (74.2%) received sleep apnea diagnoses utilizing American Academy of Sleep Medicine criteria, with 61.9% of those endorsing a history of chronic pain. Of those endorsing chronic pain, the average pain score was 4.8 (standard deviation = 2.1), with a mean interference score of 5.3 (2.7). Pairwise comparisons revealed that those endorsing a chronic pain experience at follow-up experienced categorically worse indicators of sleep-related breathing disorders during acute rehabilitation relative to those who did not endorse chronic pain. Important differences were observed with elevations on central (chronic pain: 2.6; no pain: 0.8 per hour) and obstructive apnea (chronic pain: 15.7; no pain: 11.1 per hour) events, as well as oxygen desaturation indices (chronic pain: 19.6; no pain: 7.9 per hour).

CONCLUSIONS

Sleep-disordered breathing appears worse among those who endorse chronic pain following moderate-to-severe TBI, but additional research is needed to understand its relation to postinjury pain. Prospective investigation is necessary to determine how clinical decisions (eg, opioid therapy) and intervention (eg, positive airway pressure) may mutually influence outcomes.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Comparison of Sleep Apnea Assessment Strategies to Maximize TBI Rehabilitation Participation and Outcome (C-SAS); URL: https://clinicaltrials.gov/ct2/show/NCT03033901; Identifier: NCT03033901.

CITATION

Martin AM, Pinto SM, Tang X, et al. Associations between early sleep-disordered breathing following moderate-to-severe traumatic brain injury and long-term chronic pain status: a Traumatic Brain Injury Model Systems study. J Clin Sleep Med. 2023;19(1):135-143.

Effectiveness, cost-utility and physiological underpinnings of the FIBROWALK multicomponent therapy in online and outdoor format in individuals with fibromyalgia: Study protocol of a randomized, controlled trial (On&Out study)

Introduction: The On&Out study is aimed at assessing the effectiveness, cost-utility and physiological underpinnings of the FIBROWALK multicomponent intervention conducted in two different settings: online (FIBRO-On) or outdoors (FIBRO-Out). Both interventions have proved to be efficacious in the short-term but there is no study assessing their comparative effectiveness nor their long-term effects. For the first time, this study will also evaluate the cost-utility (6-month time-horizon) and the effects on immune-inflammatory biomarkers and Brain-Derived Neurotrophic Factor (BDNF) levels of both interventions. The objectives of this 6-month, randomized, controlled trial (RCT) are 1) to examine the effectiveness and cost-utility of adding FIBRO-On or FIBRO-Out to Treatment-As-Usual (TAU) for individuals with fibromyalgia (FM); 2) to identify pre-post differences in blood biomarker levels in the three study arms and 3) to analyze the role of process variables as mediators of 6-month follow-up clinical outcomes. Methods and analysis: Participants will be 225 individuals with FM recruited at Vall d'Hebron University Hospital (Barcelona, Spain), randomly allocated to one of the three study arms: TAU vs. TAU + FIBRO-On vs. TAU + FIBRO-Out. A comprehensive assessment to collect functional impairment, pain, fatigue, depressive and anxiety symptoms, perceived stress, central sensitization, physical function, sleep quality, perceived cognitive dysfunction, kinesiophobia, pain catastrophizing, psychological inflexibility in pain and pain knowledge will be conducted pre-intervention, at 6 weeks, post-intervention (12 weeks), and at 6-month follow-up. Changes in immune-inflammatory biomarkers [i.e., IL-6, CXCL8, IL-17A, IL-4, IL-10, and high-sensitivity C-reactive protein (hs-CRP)] and Brain-Derived Neurotrophic Factor will be evaluated in 40 participants in each treatment arm (total n = 120) at pre- and post-treatment. Quality of life and direct and indirect costs will be evaluated at baseline and at 6-month follow-up. Linear mixed-effects regression models using restricted maximum likelihood, mediational models and a full economic evaluation applying bootstrapping techniques, acceptability curves and sensitivity analyses will be computed. Ethics and dissemination: This study has been approved by the Ethics Committee of the Vall d'Hebron Institute of Research. The results will be actively disseminated through peer-reviewed journals, conference presentations, social media and various community engagement activities. Trial registration number NCT05377567 (clinicaltrials.gov).

Combined effects of lifestyle and psychosocial factors on central sensitization in patients with chronic low back pain: A cross-sectional study

BACKGROUND

Central sensitization is one cause of chronic low back pain. Lifestyle and psychosocial factors are involved in the exacerbation of central sensitization. However, the combined effects of these factors on central sensitization in patients with chronic low back pain are unclear. The objective of this study was to investigate the combined effects of lifestyle and psychosocial factors on central sensitization in patients with chronic low back pain.

METHODS

This was a cross-sectional study. The participants were recruited from three orthopedic clinics for a total of 70 patients with chronic low back pain. Data were analyzed using hierarchical multiple regression analysis. In Model 1, lifestyle factors such as sleep quality, physical activity, sitting time, and perceived stress were included. Model 2 included psychosocial factors (pain catastrophizing, anxiety, and depression).

RESULTS

The data showed that sleep (b = 0.30) and perceived stress (b = 0.47) were significantly correlated in Model 1, and anxiety (b = 0.41) and perceived stress (b = 0.27) were significantly correlated in Model 2. Furthermore, contributions from sleep (b = 0.14) decreased, and no significant correlations were observed. The coefficient of determination increased significantly from Model 1 to Model 2 (ΔR ² = 0.12, p < 0.05).

CONCLUSIONS

In this study, we clarified that perceived stress and anxiety were correlated with central sensitization in patients with chronic low back pain. In addition, sleep quality mediates anxiety and may be associated with central sensitization.

The Influence of Sleep Disturbance on Chronic Pain

PURPOSE OF REVIEW

The purpose of this review is to present an overview of common sleep disturbance pathologies and their impact on chronic pain, while examining various factors that are implicit in the relationship between sleep disturbance and chronic pain, including neurobiochemistry, anatomy, and systemic mediators, and reviewing recent and landmark literature.

RECENT FINDINGS

Earlier literature reviews and studies have introduced the bidirectional relationship between sleep disturbance and chronic pain; that is, impaired sleep may worsen chronic pain, and chronic pain causes sleep disturbance. However, more recent reviews and studies seem to show a more associative, rather than causative relationship. There have been recent studies that attempt to determine mechanisms that link sleep disturbance and chronic pain; the results of these studies were more varied, ultimately concluding that there may be a separate, yet-to-be discovered mechanism that shows the causative relationship between sleep disturbance and pain. There are several neurotransmitters that are involved in the mediation of chronic pain and sleep disturbance as separate entities, and some studies have shown that there may be mechanisms that govern both chronic pain and sleep disturbance as a single unit. Other neuroendocrine substances also serve to mediate chronic pain and sleep disturbance. All these substances are found to be associated with various sleep disorders and are also associated with chronic pain symptoms as well. Inflammation plays a role in chronic pain and sleep disturbance, with an increase in inflammatory substances and mediators associated with an increase or worsening in chronic pain symptoms and sleep disorders. The HPA axis plays a role in chronic pain and sleep disorders, influencing pain and sleep pathways through stress response, inflammation, and maintenance of homeostasis. There are several variables that influence both chronic pain and sleep disturbance, and more research into these variables may further our understanding into the complex pathways governing the influence of sleep disturbance on pain, and ultimately to improve treatment for this issue.

Combining Cognitive Behavioral Therapy for Insomnia and Chronic Spinal Pain Within Physical Therapy: A Practical Guide for the Implementation of an Integrated Approach

Most people who have nonspecific chronic spinal pain (nCSP) report comorbid insomnia. However, in current treatment strategies for nCSP, insomnia is usually not addressed. Considering the bidirectional interaction between pain and sleep and its underlying psychophysiological mechanisms, insomnia may increase the risk of developing adverse physical and psychological health outcomes and should thus no longer be left untreated. As suggested by previous pilot studies, adding cognitive behavioral therapy for insomnia to the contemporary evidence-based biopsychosocial physical therapy approach may also improve pain outcomes in nCSP. This manuscript aims to provide practical guidelines on hybrid physical therapy, including the combination of the following components: (1) pain neuroscience education (eg, to reconceptualize pain) and cognition-targeted exercise therapy (eg, graded exposure to functional daily life movements), and (2) cognitive behavioral therapy for insomnia (sleep psychoeducation, behavioral and cognitive therapy, correction of sleep hygiene, and relaxation therapy) can be deployed for the management of patients who have chronic spinal pain. Impact. Due to the major impact sleep disturbances have on pain and disability, insomnia as a comorbidity should no longer be ignored when treating patients with chronic spinal pain.

Reactive Oxygen Species Contributes to Type 2 Diabetic Neuropathic Pain via the Thioredoxin-Interacting Protein-NOD-Like Receptor Protein 3-N-Methyl-D-Aspartic Acid Receptor 2B Pathway

BACKGROUND

The number of patients with diabetic neuropathic pain (DNP) continues to increase, but available treatments are limited. This study aimed to examine the influence of reactive oxygen species (ROS)-thioredoxin-interacting protein (TXNIP)-NOD-like receptor protein 3 (NLRP3)-N-methyl-D-aspartic acid receptor 2B (NR2B) pathway on type 2 DNP.

METHODS

Male Sprague-Dawley rats were fed with a high-fat and high-sugar diet for 8 weeks. Then, rats were intraperitoneally injected with streptozotocin (STZ, 35 mg/kg) to induce type 2 diabetes mellitus in rats. Diabetic rats with <85% of their basic levels in mechanical withdrawal threshold and thermal withdrawal latency were classified as DNP rats on day 14 after STZ injection. DNP rats were treated with ROS scavenger N-tert-Butyl-α-phenylnitrone (PBN, 100 mg·kg-1·d-1) or TXNIP small interfering ribonucleic acid (10 μg/d) once daily for 14 days. The level of ROS, protein levels of NLRP3, TXNIP, cysteinyl aspartate-specific proteinase-1 (caspase-1), interleukin-1β (IL-1β), NR2B phosphorylation at Tyr1472 (p-NR2B), total NR2B (t-NR2B), and distribution of NLRP3 in the spinal cord were examined. In vitro experiments, BV2 cells and PC12 cells were individually cultured and cocultured in a high-glucose environment (35 mmol/L D-glucose). The level of ROS and protein levels of NLRP3, TXNIP, caspase-1, and IL-1β in BV2 cells, and p-NR2B, t-NR2B in PC12 cells were detected. The level of ROS was detected by the flow cytometry approach. The protein levels were detected by the Western blot technique. The location of NLRP3 was observed by immunofluorescent staining. The interaction between TXNIP and NLRP3 was detected by coimmunoprecipitation assay.

RESULTS

The level of spinal ROS increased in DNP rats. The mechanical allodynia and thermal hyperalgesia of DNP rats were alleviated after systemic administration of PBN. This administration decreased protein levels of NLRP3, TXNIP, caspase-1, IL-1β, and p-NR2B and the coupling of TXNIP to NLRP3 in spinal cords of DNP rats. Furthermore, knockdown of spinal TXNIP alleviated nociceptive hypersensitivity and decreased protein levels of NLRP3, TXNIP, caspase-1, IL-1β, and p-NR2B in DNP rats. The level of ROS and protein levels of NLRP3, TXNIP, caspase-1, IL-1β, the coupling of TXNIP to NLRP3, and the IL-1β secretion increased in BV2 cells, and the protein expression of p-NR2B increased in cocultured PC12 cells in a high-glucose environment. All of these in vitro effects were significantly blocked after treatment of PBN.

CONCLUSIONS

Our findings suggest that spinal ROS can contribute to type 2 DNP through TXNIP-NLRP3-NR2B pathway.

Psychoneuroimmunology of Meditation

Background:

Meditation is a conscious mental discipline, that has been implicated in the relaxation response. The mechanism behind such a relaxing effect is psychoneuroimmunology (PNI), based on the interaction between mind, physical health, and self-healing; that conceptualizes that stress and an individual’s emotional state led to predisposition to diseases. Research to date suggests that meditation may play an active role in remodeling the imbalance between mind and body by modulating the psychoneuroimmunological effects of stress. However, to date, the multi-dimensional psychoneuroimmune aspects of meditation together have not been completely explicated. An evidence-based mechanism has been framed for the first time in India to explain the psychoneuroimmunology of regular and long-term meditation practice.

Summary:

Present evidence-based mechanism confirms prefrontal cortex (PFC) acts as a ‘Functional Connectome’ where psycho-neuro-immune aspects of meditation function simultaneously to exert positive benefits in the regulation of cognitive and emotional behavior. Also, this mechanism will help us to understand how human augmentation with lifestyle modification fosters brain plasticity to overcome various neuropsychiatric illnesses.

Key Message:

Meditation is a scientific tool against neuro-psychiatric illnesses.

Sleep Problems Mediate the Relationship Between Psychosocial Stress and Pain Facilitation in Native Americans: A Structural Equation Modeling Analysis from the Oklahoma Study of Native American Pain Risk

BACKGROUND

Native Americans (NAs) are more likely to experience chronic pain than non-Hispanic Whites (NHWs); however, the proximate causes predisposing NAs to chronic pain remain elusive. Likely due to centuries of adversity, discrimination, and marginalization, NAs report greater psychological stress than NHWs, which may place them at risk for sleep problems, a well-established risk factor for chronic pain onset.

PURPOSE

This study examined the effects of psychological stress and sleep problems on subjective and physiological measures of pain processing in NAs and NHWs.

METHODS

Structural equation modeling was used to determine whether ethnicity (NA or NHW) was associated with psychological stress or sleep problems and whether these variables were related to conditioned pain modulation of pain perception (CPM-pain) and the nociceptive flexion reflex (CPM-NFR), temporal summation of pain (TS-pain) and NFR (TS-NFR), and pain tolerance in a sample of 302 (153 NAs) pain-free participants.

RESULTS

NAs experienced more psychological stress (Estimate = 0.027, p = .009) and sleep problems (Estimate = 1.375, p = .015) than NHWs. When controlling for age, sex, physical activity, BMI, and general health, NA ethnicity was no longer related to greater sleep problems. Psychological stress was also related to sleep problems (Estimate = 30.173, p = <.001) and psychological stress promoted sleep problems in NAs (indirect effect = 0.802, p = .014). In turn, sleep problems were associated with greater TS-pain (Estimate = 0.714, p = .004), but not other pain measures.

CONCLUSIONS

Sleep problems may contribute to chronic pain risk by facilitating pain perception without affecting facilitation of spinal neurons or endogenous inhibition of nociceptive processes. Since psychological stress promoted pain facilitation via enhanced sleep problems, efforts to reduce psychological stress and sleep problems among NAs may improve health outcomes.

Inflammatory Bowel Disease and Pain Interference: A Conceptual Model for the Role of Insomnia, Fatigue, and Pain Catastrophizing

Background

People with inflammatory bowel disease (IBD) commonly experience pain influenced by complex interactions among factors, including disease activity, sleep, psychopathology, and changes in pain processing pathways. Treatments for pain in IBD are limited, highlighting the need for research that explores modifiable factors linked to pain. The aim of this study was to investigate relationships among multiple patient factors and to construct a conceptual model for pain interference in IBD.

Methods

A cross-sectional survey of adults with IBD. Study domains included demographic, comorbidity, psychological, IBD, insomnia, fatigue, and pain features. Structural equation modeling (SEM) was used to examine relationships and interactions among active IBD, insomnia, fatigue, pain experiences (severity, catastrophizing, and interference), and additional patient factors (demographics and psychological).

Results

One hundred and seventy-four participants, aged 18-85 years, reported the presence of pain. Combining the questionnaire data using SEM resulted in a final model with an excellent fit (χ 2(8) = 9.579, P = .297, χ 2/N = 1.197, CFIN = 0.997, TLI = 0.987, RMSEA = 0.034). The presence of anxiety and depression was the additional patient factors to be retained in the path analysis. SEM results indicated that greater pain interference was directly influenced by greater fatigue, worse pain catastrophizing, and worse pain severity. Pain interference was indirectly impacted by IBD activity, worse insomnia, and the presence of depression and anxiety.

Conclusions

The proposed conceptual model highlights the role of multiple potentially modifiable factors, including insomnia, pain catastrophizing, and fatigue, contributing to worse pain interference in people with IBD.

People Have Mixed Reactions to Both Physiological and Psychological Explanations of Disproportionate Pain

BACKGROUND

There are two general frameworks that conceptualize pain that is more intense or persistent than expected based on measurable pathologic findings: the psychological (unhelpful thoughts and emotions) and the physiological (purported nervous system dysfunction, such as central sensitization). Some clinicians believe people will be more receptive to a physiological conceptualization. Prior quantitative research demonstrated that carefully crafted psychological explanations are rated similarly to crafted physiological explanations, with relatively mixed reactions. This qualitative study was undertaken in parallel with that quantitative study to help develop effective communication and treatment strategies by identifying specific thoughts and feelings (themes) regarding the physiological and psychological conceptualizations of disproportionate pain that make people more or less comfortable considering comprehensive, biopsychosocial treatment approaches.

QUESTION/PURPOSE

What themes arise in patient thoughts and feelings regarding physiological and psychological conceptualizations of pain that is more intense or persistent than expected?

METHODS

We sought to understand the experience of considering pain as a biopsychosocial experience (phenomenology approach) by studying the thoughts and feelings that arise as people seeking care for arm and back pain engage with physiological and psychological conceptualizations of pain that is more intense or persistent than one would expect based on the pathology. We recruited 29 patients presenting for upper extremity or back pain specialty care at one of two urban offices, intentionally recruiting people of various ages, genders, backgrounds, socioeconomic status, as well as type and duration of pain (purposive sampling). The 29 patients included 18 women and 11 men (16 married, 15 non-White, 20 with arm pain) with a median (interquartile range) age of 62 years (42 to 67). The interviews were conducted by a trained woman orthopaedic surgeon interviewer using a semistructured interview guide soliciting participants' thoughts and feelings about a physiological explanation (nerves in the central nervous system stuck in the on position can make pain more intense) and a psychological explanation (unhelpful thoughts and feelings of distress can make pain more intense) for pain more intense or persistent than expected. The interviews were transcribed and themes were identified as the data were collected. Based on current experimental evidence, including what is known about the physiological effects of thoughts, feelings, and context (placebo/nocebo effects), we assumed an underlying physiological basis for pain that is variably experienced and expressed (mixed postpositive/interpretive approach). Themes were identified in the interview transcripts systematically by two coders and then discussed with the entire research team to arrive at consensus. We stopped enrolling patients when the authors agreed that additional themes did not arise in five consecutive interviews.

RESULTS

The following themes and interpretations were derived from the analysis: Neither the physiological nor the psychological explanation for disproportionate pain (1) avoided the stigma associated with mental health, (2) was consistently understood, (3) provided a consistent sense of control, (4) consistently provided hope, and (5) represented the stress and emotion of disproportionate or persistent pain. The physiological explanation also generated mixed reactions regarding whether or not it: (1) was a useful point of conversation, (2) was reassuring or frightening, and (3) supported physiological or psychological treatments. The psychological explanation made some people feel worse.

CONCLUSION

People have mixed reactions to both physiological and psychological explanations of disproportionate pain. As such, without direction on content, communication might be most effective by focusing on relational aspects, such as emotional connection and trust.

CLINICAL RELEVANCE

Although there is room to improve the content of strategies for explaining more pain than expected to patients, our findings extend the discoveries of others in highlighting the need for tailored relational communication strategies that prioritize feeling heard, validated, and accompanied.

SYSTEMIC CYTOKINE LEVEL DIFFERENCES IN PATIENTS WITH CHRONIC MUSCULOSKELETAL SPINAL PAIN COMPARED TO HEALTHY CONTROLS AND ITS ASSOCIATION WITH PAIN SEVERITY: A SYSTEMATIC REVIEW

OBJECTIVE

Although there has been increasing interest in the role of systemic cytokines in chronic spinal pain (CSP), the evidence on their potential contribution is still unclear. Therefore, the current study systematically reviewed the evidence on systemic cytokine level differences between people with CSP compared to healthy controls (HCs) and the potential associations with pain severity.

METHODS

An electronic search was conducted on PubMed, Web of Science and Embase. All included studies were classified as observational studies, exploring the comparison between a CSP group and a HC group, and the association between systemic cytokine levels and pain severity.

RESULTS

Nine articles were included with a total sample of 400 CSP patients suffering from chronic whiplash associated disorder (CWAD) or chronic low back pain (CLBP). In CLBP, moderate evidence was found for elevated tumor necrosis factor (TNF) α, interleukin (IL) 6, IL-1 receptor antagonist (IL-1RA), and soluble TNF receptor (sTNF-R) type 2, for normal interferon (IFN) γ and IL-2 levels, and for reduced IL-10 levels. No association was found between pain severity and these cytokines in CLBP. In CWAD, moderate evidence was found for elevated CRP and evidence for changes in TNF-α was inconclusive. Evidence for the association between pain severity and CRP was limited, and there is probably no association between pain severity and TNF-α with limited evidence in CWAD.

CONCLUSIONS

Moderate evidence indicates the presence of systemic inflammation in CSP. Evidence regarding the association between pain severity and systemic cytokines is inconclusive and limited.

Social factors and chronic pain: the modifying effect of sex in the Stockholm Public Health Cohort Study

OBJECTIVES

To assess the relationship between social factors (socio-economic status, household load and job strain) and chronic pain occurrence, and the role of gender in this relationship.

METHODS

We used data corresponding to 8 years of follow-up of the Stockholm Public Health Cohort Study (2006-2014) to compute Adjusted Incidence Rate Ratios (IRRs) and additive interaction measures of chronic pain episodes, social factors, and sex in 16 687 subjects.

RESULTS

For men, increased rates of chronic pain occurrence were observed for skilled workers (IRR = 1.27, 95% CI: 0.99, 1.61) and lower non-manual employees (IRR = 1.37, 95% CI: 1.05, 1.78), compared with unskilled workers; subjects with high household load (IRR = 1.39; 95% CI: 1.03, 1.88), compared with those with a null score; and subjects with active jobs (IRR = 1.27, 95% CI: 1.06, 1.51), compared with those with low-strain jobs. For women, we observed decreased rates of chronic pain occurrence in lower (IRR = 0.82, 95% CI: 0.68, 0.99), intermediate (IRR = 0.74, 95% CI: 0.63, 0.88) and higher non-manual employees (IRR = 0.65, 95% CI: 0.54, 0.79), compared with unskilled workers. Compared with subjects with a null score, women with low household load showed a lower rate of chronic pain occurrence (IRR = 0.85; 95% CI: 0.72, 1.00). Compared with subjects with low-strain jobs, those with passive jobs (IRR = 1.21; 95% CI: 1.02, 1.44) and high-strain jobs (IRR = 1.46; 95% CI: 1.02, 2.09) showed higher rates of chronic pain occurrence.

CONCLUSION

In general, our analysis yielded different, if not opposite, results when data were stratified by sex. Sex may then represent an effect modifier of the relationship between social factors and chronic pain.

Somatosensory assessments in patients with inflammatory bowel disease: a cross-sectional study examining pain processing pathways and the role of multiple patient factors

BACKGROUND

Pain affects the majority of patients with inflammatory bowel disease (IBD), where pain experiences may be influenced by multiple patient factors and changes within central pain processing pathways, termed central sensitization. The current study aimed to investigate pain processing pathways in patients with IBD through somatosensory testing and associations with multiple patient factors.

METHODS

A cross-sectional study of adults with IBD. Assessments included: somatosensory tests [i.e. pressure pain thresholds (PPT), temporal summation (TS), conditioned pain modulation (CPM)], and patient factors (i.e. demographics, comorbidity, sleep quality, psychological, pain severity and interference, and IBD features). Multiple regression analyses explored associations between somatosensory tests and multiple patient factors.

RESULTS

Decreased CPM in participants (N = 51) was associated with worse abdominal pain severity and use of biologic therapies (R2 = 0.30, F(5,44) = 5.18, P = 0.001). Increased TS was associated with biologic use (R2 = 0.11, F(1,49) = 6.13, P = 0.017). Decreased PPT at the low back (R2 = 0.29, F(2,48) = 11.21, P < 0.001) and Tibialis anterior (R2 = 0.41, F(2,48) = 18.26, P < 0.001) were associated with female sex and the absence of a stoma.

CONCLUSION

Study results demonstrated associations between multiple patient factors and somatosensory tests in patients with IBD. The absence of a stoma and female sex was associated with greater sensitivity to pressure in two remote body regions, suggestive of widespread hyperalgesia. Worse abdominal pain severity and biologic use were associated with decreased pain inhibition, and biologic use was also associated with increased pain facilitation. These findings suggest the presence of altered pain processing and mechanisms of central sensitization in patients with IBD.

Noninvasive intracranial pressure monitoring in women with migraine

This cross-sectional study aimed to compare the waveform morphology through noninvasive intracranial pressure (ICP-NI) measurement between patients with migraine and controls, and to analyze the association with clinical variables. Twenty-nine women with migraine, age 32.4 (11.2) years and headache frequency of 12.6 (7.5) days per month and twenty-nine women without headache, age 32.1 (9.0) years, were evaluated. Pain intensity, migraine disability, allodynia, pain catastrophizing, central sensitization and depression were evaluated. The ICP-NI monitoring was performed by a valid method consisting of an extracranial deformation sensor positioned in the patients’ scalp, which allowed registration of intracranial pressure waveforms. Heart rate and blood pressure measurements were simultaneously recorded during 20 min in the supine position. The analyzed parameter was the P2/P1 ratio based on mean pulse per minute which P1 represents the percussion wave related to the arterial blood pression maximum and P2 the tidal wave, middle point between the P1 maximum and the dicrotic notch. There was no between-groups difference in the P2/P1 ratio (mean difference: 0.04, IC95%: -0.07 to 0.16, p = 0.352, F (1,1) = 0.881) adjusted by body mass index covariable. The Multiple Linear Regression showed non-statistical significance [F (5,44) = 1.104; p = 0.372; R² = 0.11)] between the P2/P1 ratio and body mass index, presence of migraine, central sensitization, pain catastrophizing and depression. We found no correlation (p > 0.05) between P2/P1 ratio and migraine frequency, migraine onset, pain intensity, pain intensity at day of examination, disability, allodynia. Migraine patients did not present alterations in the waveform morphology through ICP-NI compared to women without headache and no association with clinical variables was found.

Neck pain: global epidemiology, trends and risk factors

BACKGROUND

Neck pain is one of the most common musculoskeletal disorders, having an age-standardised prevalence rate of 27.0 per 1000 population in 2019. This literature review describes the global epidemiology and trends associated with neck pain, before exploring the psychological and biological risk factors associated with the initiation and progression of neck pain.

METHODS

The PubMed database and Google Scholar search engine were searched up to May 21, 2021. Studies were included that used human subjects and evaluated the effects of biological or psychological factors on the occurrence or progression of neck pain, or reported its epidemiology.

RESULTS

Psychological risk factors, such as long-term stress, lack of social support, anxiety, and depression are important risk factors for neck pain. In terms of the biological risks, neck pain might occur as a consequence of certain diseases, such as neuromusculoskeletal disorders or autoimmune diseases. There is also evidence that demographic characteristics, such as age and sex, can influence the prevalence and development of neck pain, although further research is needed.

CONCLUSIONS

The findings of the present study provide a comprehensive and informative overview that should be useful for the prevention, diagnosis, and management of neck pain.