The pain of fibromyalgia syndrome is due to muscle hypoperfusion induced by regional vasomotor dysregulation

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

ABSTRACT

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

The effect of the EXOPULSE Mollii Suit on pain and fibromyalgia-related symptoms-A randomized sham-controlled crossover trial

BACKGROUND

Fibromyalgia pain and related symptoms are poorly managed by approved pharmacological and alternative interventions. This trial aimed to evaluate the effects of the EXOPULSE Mollii Suit-a multisite transcutaneous electrical nerve stimulation device-on fibromyalgia pain, fatigue, affective symptoms, disease impact, and quality of life.

METHODS

Adult patients with fibromyalgia were enrolled. Phase 1 implied a randomized, sham-controlled, cross-over, double-blind trial, applying daily 1 h sessions of active or sham intervention, over 2 weeks (2-week washout). In the open-label phase 2, all patients received daily active intervention for 4 weeks. Comparisons on pain, fatigue, disease impact, affective symptoms, quality of life, clinical impression, and comfort ratings were performed using Friedman, Wilcoxon signed rank, and Chi2 tests.

RESULTS

Thirty-three patients completed the study (93.9% female, mean age: 51.3 years). Pain (primary endpoint assessed via a visual analog scale) was significantly reduced after the active (pre-active: 6.9 ± 1.4, post-active: 5.9 ± 1.8, pre-sham: 6.8 ± 1.4, post-sham: 6.6 ± 1.5) versus the sham intervention (X2 = 10.60, p = 0.014). This was also the case of other secondary endpoints (i.e., fatigue, anxiety, and disease impact), except depression and quality of life. The Clinical Global Impression of Change (CGI-C) was significantly different between the active and sham intervention periods (X2 p = 0.035), and the different proportions of categories were as follows: 'worsening' (sham: 18.2% vs. active: 0.0%), 'improvement' (sham: 48.5% vs. active 63.6%) or 'no change (sham: 33.3% vs. active 36.4%) respectively. After phase 2, significant positive effects were observed for most of the outcomes, and 78.8% of patients reported improvement according to CGI-C.

CONCLUSIONS

This study suggests the clinical benefits of the EXOPULSE Mollii Suit in alleviating pain and fibromyalgia-related fatigue, emotional symptoms, and disease impact. It is worth noting that the study has several limitations related to the low number of participants, the short-term analysis of effects in the first blinded and controlled phase, and the open-label nature of phase 2. Future studies with a larger cohort and longer protocol treatment are needed, to further confirm the current results, and evaluate the long-term effects of this technique.

SIGNIFICANCE

Patients with fibromyalgia suffer from pain as well as fatigue, sleep impairment, emotional disturbances, and altered quality of life. Transcutaneous electrical nerve stimulation might help manage those symptoms, but the available systems are limited by the fact that they could be applied at best over two sites. This randomized controlled study is the first to apply a multi-site transcutaneous electrical nerve stimulation device, the EXOPULSE Mollii Suit, with significant effects on fibromyalgia pain and related symptoms.

Muscle Pressure Correlates With Pain Levels in Fibromyalgia Patients

BACKGROUND/OBJECTIVE

We evaluated patients with fibromyalgia syndrome (FMS) to determine whether there is a correlation between pain scores based on a 0- to 10-point visual analog scale (VAS) and muscle pressure.

METHODS

One hundred forty-two patients who satisfied the American College of Rheumatology classification criteria for FMS and 38 non-FMS controls comprised the study groups. Muscle pressure was measured in mm Hg using a pressure gauge attached to a no. 22 needle inserted into the midportion of the trapezius muscle. The muscle pressure was then correlated with the VAS pain score of 0 to 10, some with an increment of 0.5. A second muscle pressure was obtained from 19 patients at a subsequent visit, which was compared with their pain scores.

RESULTS

The mean (SD) pain score for 142 patients with FMS was 6.6 (SD, 1.84) on a 0- to 10-point VAS. The mean pain score in the non-FMS subjects was 0.7 (SD, 1.26). The mean muscle pressure in the FMS group was 32.9 (SD, 6.57) mm Hg. The mean muscle pressure in the non-FMS subjects was 10.6 (SD, 3.85) mm Hg. The calculated Pearson correlation coefficient for muscle pressure versus pain score was 0.8312 ( p < 0.0001). This indicates a highly significant association between subjects' muscle pressure and pain scores. For the repeat muscle pressures, the change in muscle pressure was correlated with the change in pain score, and the resulting Pearson correlation coefficient was 0.9255 ( p < 0.0001). These results again indicate a highly significant association between subjects' muscle pressure and pain scores.

CONCLUSION

The results show that increased muscle pressure may be a significant cause of pain in FMS, and the etiology of the pain may have a large peripheral component in addition to a centralized origin of the pain.

Impact of homeostatic body hydration status, evaluated by hemodynamic measures, on different pain sensitization paths to a chronic pain syndrome

Contrasting findings on the mechanisms of chronic pain and hypertension development render the current conventional evidence of a negative relationship between blood pressure (BP) and pain severity insufficient for developing personalized treatments. In this interdisciplinary study, patients with fibromyalgia (FM) exhibiting clinically normal or elevated BP, alongside healthy participants were assessed. Different pain sensitization responses were evaluated using a dynamic 'slowly repeated evoked pain' (SREP) measure, as well as static pain pressure threshold and tolerance measures. Cardiovascular responses to clino-orthostatic (lying-standing) challenges were also examined as acute re- and de-hydration events, challenging cardiovascular and cerebrovascular homeostasis. These challenges involve compensating effects from various cardiac preload or afterload mechanisms associated with different homeostatic body hydration statuses. Additionally, hair cortisol concentration was considered as a factor with an impact on chronic hydration statuses. Pain windup (SREP) and lower pain threshold in FM patients were found to be related to BP rise during clinostatic (lying) rehydration or orthostatic (standing) dehydration events, respectively. These events were determined by acute systemic vasoconstriction (i.e., cardiac afterload response) overcompensating for clinostatic or orthostatic cardiac preload under-responses (low cardiac output or stroke volume). Lower pain tolerance was associated with tonic blood pressure reduction, determined by permanent hypovolemia (low stroke volume) decompensated by permanent systemic vasodilation. In conclusion, the body hydration status profiles assessed by (re)activity of systemic vascular resistance and effective blood volume-related measures can help predict the risk and intensity of different pain sensitization components in chronic pain syndrome, facilitating a more personalized management approach.

Vasodilatory Peripheral Response and Pain Levels following Radiofrequency Stressor Application in Women with Fibromyalgia

Fibromyalgia (FM) is a syndrome of unknown pathogenesis that presents, among other symptoms, chronic widespread musculoskeletal pain. This study aims to analyze the effects of radiofrequency on core body temperature and the peripheral temperature of the dorsal surfaces and palms of the hands and its association with pain levels in patients with FM. A case-control observational study was conducted with a total of twenty-nine women diagnosed with FM and seventeen healthy women. Capacitive monopolar radiofrequency was applied to the palms of the hands using the Biotronic Advance Develops device. Peripheral hand temperature was analyzed using a thermographic camera, and core body temperature was analyzed with an infrared scanner. Pressure pain thresholds (PPTs) and electrical pain were recorded with an algometer and a Pain Matcher device, respectively. A significant decrease was observed in women with FM in pain electrical threshold (95% CI [0.01-3.56], p = 0.049), electrical pain (95% CI [2.87-10.43], p = 0.002), dominant supraspinatus PPT (95% CI [0.04-0.52], p = 0.023), non-dominant supraspinatus PPT (95% CI [0.03-0.60], p = 0.029), and non-dominant tibial PPT (95% CI [0.05-0.89], p = 0.031). Women with FM have increased hypersensitivity to pain as well as increased peripheral temperature after exposure to a thermal stimulus, such as radiofrequency, which could indicate disorders of their neurovascular response.

A Phase 1 randomized, open-label clinical trial to evaluate the effect of a far-infrared emitting patch on local skin perfusion, microcirculation and oxygenation

Far-infrared radiation (FIR) has been investigated for reduction of pain and improvement of dermal blood flow. The FIRTECH patch is a medical device designed to re-emit FIR radiated by the body. This phase 1 study was conducted to evaluate the local effects of the FIRTECH patch on local skin perfusion, microcirculation and oxygenation. This prospective, randomized, open-label, parallel designed study admitted 20 healthy participants to a medical research facility for treatment for 31 h on three anatomical locations. During treatment, imaging assessments consisting of laser speckle contrast imaging, near-infrared spectroscopy, side-stream dark-field microscopy, multispectral imaging and thermography were conducted regularly on patch-treated skin and contralateral non-treated skin. The primary endpoint was baseline perfusion increase during treatment on the upper back. Secondary endpoints included change in baseline perfusion, oxygen consumption and temperature of treated versus untreated areas. The primary endpoint was not statistically significantly different between treated and non-treated areas. The secondary endpoints baseline perfusion on the forearm (least square means [LSMs] difference 2.63 PU, 95% CI: 0.97, 4.28), oxygen consumption (LSMs difference: 0.42 arbitrary units [AUs], 95% CI: 0.04, 0.81) and skin temperature (LSMs difference 0.35°C, 95% CI: 0.16, 0.6) were statistically significantly higher in treated areas. Adverse events observed during the study were mild and transient. The vascular response to the FIRTECH patch was short-lived suggesting a non-thermal vasodilatory effect of the patch. The FIRTECH patch was well tolerated, with mild and transient adverse events observed during the study. These results support the therapeutic potential of FIR in future investigations.

Fibromyalgia: Could hyperbaric oxygen therapy make the difference? Our experience

Fibromyalgia is a rare disease, difficult to diagnose and to treat. We think that hyperbaric oxygen therapy could improve its signs and symptoms although more evidences have to be accumulated.

Mechanisms hypothesized for pain-relieving effects of exercise in fibromyalgia: a scoping review

Background

Exercise is one of the most recommended management strategies by treatment guidelines for fibromyalgia (FM); however, the mechanism through which exercise improves pain in FM is still unknown.

Objective

We aimed to summarize the hypothesized theoretical mechanisms for the pain-relieving effects of exercise in people with FM.

Eligibility Criteria

Randomized controlled trials (RCTs) in English reporting mechanisms for pain-relieving effects of exercise in the 'Introduction' and 'Discussion' sections and significant within- group or between-group effects of exercise interventions were included.

Sources of Evidence

We searched the databases Ovid MEDLINE(R), EMBASE, CINAHL, COCHRANE, Sports Discuss, and AMED with the keywords: exercise and fibromyalgia until December 2021.

Charting Methods

Two authors independently performed title/abstract, full-text review, and data abstraction using a data abstraction form. The hypothesized mechanisms from individual studies were grouped into three categories.

Results

The literature search resulted in 2147 studies, out of which 220 studies were considered for full-text review. A total of 50 RCTs proposing 29 unique mechanisms for the pain-relieving effects of exercise were included. These mechanisms were divided into three categories: physical, neuro-physiological, and psychological. The neuro-physiological category was further subdivided into exercise-induced hypoalgesia (EIH), pain sensitization, the autonomic system, the immune system, the endocrine system, and miscellaneous categories. The most frequently hypothesized mechanisms were EIH (n = 15), autonomic modulation (n = 7), improved sleep (n = 6), muscle oxygenation (n = 6), self-efficacy (n = 5), mental health (n = 4), and benefits of the aquatic environment (n = 12). While all exercise interventions involved FM patients, most of the supporting evidence for these mechanisms was cited from previous studies conducted on healthy samples. No studies performed analyses to demonstrate causal associations between the mechanisms and outcomes.

Conclusion

Multiple mechanisms were hypothesized for the positive influence of exercise in people with FM. Future studies using causal analyses, such as mediation analysis, are recommended to validate these mechanisms.

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

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

Acute Effects of a Session with The EXOPULSE Mollii Suit in a Fibromyalgia Patient: A Case Report

Fibromyalgia is a chronic disorder characterized by widespread musculoskeletal pain and associated fatigue, sleep disturbances, and other cognitive and somatic symptoms. A multidisciplinary approach including pharmacological therapies along with behavioral therapy, exercise, patient education, and pain management is a possible solution for the treatment of this disease. The EXOPULSE Mollii^® method (EXONEURAL NETWORK AB, Danderyd, Sweden) is an innovative approach for non-invasive and self-administered electrical stimulation with multiple electrodes incorporated in a full-body suit, with already proven benefits for other diseases. Therefore, the present case report study aims to evaluate the effects that a 60 min session with the EXOPULSE Mollii suit has on a female fibromyalgia patient. After the intervention, we can conclude that a 60 min session with the EXOPULSE Mollii suit has beneficial effects on pain perception, muscle oxygenation, parasympathetic modulation, and function in a female fibromyalgia patient.

The Vastus Lateralis Muscle Interstitium Proteome Changes after an Acute Nociception in Patients with Fibromyalgia Compared to Healthy Subjects-A Microdialysis Study

Fibromyalgia (FM) is a complex disorder and a clinical challenge to diagnose and treat. Microdialysis is a valuable tool that has been used to investigate the interstitial proteins and metabolites of muscle in patients with fibromyalgia. The implantation of the catheter in the muscle causes acute tissue trauma and nociception. The aim of this study was to investigate acute proteome changes in the vastus lateralis muscle in women fibromyalgia patients (FM) and healthy subjects (CON). A further aim was to study if a 15-week resistance exercise program in FM had any influence on how chronic painful muscle responds to acute nociception. Twenty-six women patients with FM and twenty-eight CON were included in this study. A microdialysis catheter (100 kilo Dalton cut off, membrane 30 mm) was inserted in the vastus lateralis muscle, and samples were collected every 20 min. Subjects rated pain before catheter insertion, directly after, and every 20 min of sample collection. Dialysate samples from time points 0-120 were pooled and considered trauma samples due to the catheter insertion. The samples were analyzed with nano-liquid chromatography-tandem mass spectrometry (nLC-MS/MS). Advanced multivariate data analysis was used to investigate protein profile changes between the groups. Multivariate data analysis showed significant (CV-ANOVA p = 0.036) discrimination between FM and CON based on changes in 26 proteins. After the 15-week exercise intervention, the expression levels of the 15 proteins involved in muscle contraction, response to stimulus, stress, and immune system were increased to the same expression levels as in CON. In conclusion, this study shows that microdialysis, in combination with proteomics, can provide new insights into the interstitial proteome in the muscle of FM. In response to acute nociception, exercise may alter the innate reactivity in FM. Exercise may also modulate peripheral muscle proteins related to muscle contraction, stress, and immune response in patients with FM.

The Behavior of Muscle Oxygen Saturation, Oxy and Deoxy Hemoglobin during a Fatigue Test in Fibromyalgia

Previous studies have reported that people with fibromyalgia (FM) could suffer from mitochondrial dysfunction. However, the consumption of muscle oxygen during physical exercise has been poorly studied. Therefore, this study aimed to explore the response of muscle oxygen during a fatigue protocol in people with FM and healthy controls (HC). In addition, the peak torque and the total work were assessed. A total of 31 participants (eighteen were people with fibromyalgia and thirteen were healthy controls) were enrolled in this cross-sectional study. All the participants underwent a fatigue protocol consisting of 20 repetitions at 180°·s−1 of quadriceps flexions and extensions using a Biodex System 3. The muscle oxygen saturation (SmO2), total hemoglobin (THb), deoxygenated hemoglobin (HHb) and oxygenated hemoglobin (O2Hb) values were measured using a portable near-infrared spectroscopy (NIRS) device. Significant differences between people with FM and healthy controls were found at baseline: SmO2 (FM: 56.03 ± 21.36; HC: 77.41 ± 10.82; p = 0.036), O2Hb (FM: 6.69 ± 2.59; HC: 9.37 ± 1.31; p = 0.030) and HHb (FM: 5.20 ± 2.51; HC: 2.73 ± 1.32; p = 0.039); during the fatigue protocol: SmO2 (FM: 48.54 ± 19.96; HC: 58.87 ± 19.72; p = 0.038), O2Hb (FM: 5.70 ± 2.34; HC: 7.06 ± 2.09; p = 0.027) and HHb (FM: 5.69 ± 2.65; HC: 4.81 ± 2.39; p = 0.048); and in the recovery at three min and six min for SmO2, O2Hb and HHb (p < 0.005). Furthermore, healthy control values of SmO2, O2Hb and HHb have been significantly altered by the fatigue protocol (p < 0.005). In contrast, people with FM did not show any significant alteration in these values. Moreover, significant differences were found in the peak torque at extension (FM: 62.48 ± 24.45; HC: 88.31 ± 23.51; p = 0.033) and flexion (FM: 24.16 ± 11.58; HC: 42.05 ± 9.85; p = 0.010), and the total work performed at leg extension (FM: 1039.78 ± 434.51; HC: 1535.61 ± 474.22; p = 0.007) and flexion (FM: 423.79 ± 239.89; HC: 797.16 ± 194.37; p = 0.005).

Relationships of autonomic dysfunction with disease severity and neuropathic pain features in fibromyalgia: is it really a sympathetically maintained neuropathic pain?

Background

The pathophysiology of fibromyalgia (FM) involves many mechanisms including central nervous system sensitization theory, autonomic nervous system (ANS) dysfunction, and recently small fiber neuropathy. While the small fiber neuropathy itself can cause ANS dysfunction and neuropathic pain (NP), it is still unknown whether ANS problems have an association with severity of disease and NP in patients with FM. The aim of this study was to evaluate ANS dysfunction in FM patients and to explore possible associations of ANS dysfunction with disease severity and NP.

Methods

Twenty-nine FM patients and 20 healthy controls were included in this cross-sectional study. Participants were tested using sympathetic skin responses (SSR) and R-R interval variation analyses for sympathetic and parasympathetic ANS dysfunction, respectively. Disease severity and somatic symptoms of patients with FM were evaluated using the ACR-2010 scales and Fibromyalgia Impact Questionnaire, and NP symptoms were evaluated using the Pain Detect Questionnaire and Douleur Neuropathique questionnaire.

Results

FM patients were found to have ANS dysfunction characterized by increased sympathetic response and decreased parasympathetic response. SSR amplitudes were found to be correlated with a more severe disease. Although non-significant, NP severity tended to be associated with a decrease in sympathetic and parasympathetic activities.

Conclusions

ANS dysfunction may play a role in the pathophysiology of FM. The trend of decreased ANS functions in FM patients exhibiting NP contradicts the notion that FM is a sympathetically maintained NP and may be explained with small fiber involvement.

The evaluation of nailfold capillaroscopy pattern in patients with fibromyalgia

Objectives

This study aims to evaluate nailfold capillaroscopic pattern in patents with fibromyalgia and to assess the relation of capillaroscopic parameters with clinical variables and disease-related measures.

Patients and methods

This cross-sectional, case-control study included 60 participants (4 males, 56 females; mean age: 44.0±8.2 years; range, 26 to 64 years) between August 2019 and November 2019. All participants were divided into two groups as the primary fibromyalgia group (n=30) who met the 2016 modified American College of Rheumatology Diagnostic Criteria for Fibromyalgia and the control group (n=30) consisting of age- and sex-matched healthy individuals. Nailfold capillaroscopy was performed by a digital microscope under a magnification of 200X. Capillary density, capillary loop diameter, number of dilated, giant and neoangiogenic capillaries, capillary shape, number of avascular areas, micro-aneurysms and micro-hemorrhages were evaluated by an assessor who was blind to the group allocation. In the fibromyalgia group, Widespread Pain Index, Symptom Severity Scale scores, and Fibromyalgia Severity scores were calculated. Health status and presence of benign joint hypermobility syndrome (BJHS) were evaluated using the Fibromyalgia Impact Questionnaire (FIQ) and revised Brighton criteria, respectively.

Results

Of the capillaroscopic parameters, the mean capillary loop diameter, number of micro-aneurysms, avascular areas, and neoangiogenic capillaries were significantly higher in the patient group compared to the controls (p<0.001, p=0.016, p=0.038, and p=0.04, respectively). Nailfold capillaroscopic findings did not significantly differ between the patients with (n=16) and without concomitant BJHS (n=14). Of the disease-related measures, only FIQ score showed a weak correlation with the number of dilated capillaries (p=0.324).

Conclusion

Patients with fibromyalgia have distinct capillaroscopic patterns than healthy population. Capillaroscopic features, in general, are not related to clinical variables and disease-related measures.

Analysis of Retinal Layers in Fibromyalgia Patients with Premium Protocol in Optical Tomography Coherence and Quality of Life

PURPOSE

To evaluate the inner retinal layers in fibromyalgia (FM) patients compared to control subjects using posterior pole protocol (PPole) analysis in optical coherence tomography (OCT) and to correlate structural retinal changes with subjective quality of life.

METHODS

Seventy-four eyes of healthy subjects and 55 eyes of those with FM were analyzed. All subjects underwent retinal evaluation using the PPole protocol for Spectralis OCT (Heidelberg Engineering) to obtain measurements of the retinal nerve fiber layer (RNFL) and the ganglion cell layer (GCL) in the macular area. The EuroQol (EQ-5D) questionnaire and Fibromyalgia Impact Questionnaire (FIQ) were performed to analyze health-related quality of life. Additionally, the FM group was divided into three groups depending on the disease phenotype (atypical, depressive and biological).

RESULTS

: Patients with FM presented with a reduction of the RNFL thickness compared to controls in 17/64 cells of the PPole area, and a reduction of the GCL thickness in 47/64 cells. Depressive FM phenotype showed the greatest number of cells with significant reduction compared with the control group in both RNFL and GCL layers. A correlation between temporal-inferior cells of the GCL and the EuroQol 5D questionnaire results was observed.

CONCLUSIONS

Patients with FM present with a reduction of the inner retinal layers in the macular area. This degeneration correlates with disease severity/reduced quality of life in these patients. The PPole protocol for OCT is a non-invasive and fast tool that might help clinicians diagnose and monitor neurodegeneration in FM patients.

Fibromyalgia and Depression in Women: An 1H-NMR Metabolomic Study

Fibromyalgia is a chronic and systemic syndrome characterized by muscle, bone, and joint pain. It is a gender-specific condition with a 9:1 incidence ratio between women and men. Fibromyalgia is frequently associated with psychic disorders affecting the cognitive and emotional spheres. In the reported work, we compared 31 female fibromyalgia patients to 31 female healthy controls. They were analyzed for biochemical clinical parameters, for autoimmune markers, and were subjected to 1H-NMR metabolomics analysis. To identify a correlation between the metabolomic profile and the psychic condition, a subset of 19 fibromyalgia patients was subjected to HAM-A and HAM-D Hamilton depression tests. Multivariate statistical analysis showed the dysmetabolism of several metabolites involved in energy balance that are associated with systemic inflammatory conditions. The severity of depression worsens dysmetabolic conditions; conversely, glycine and glutamate, known for their critical role as neuromodulators, appear to be potential biomarkers of fibromyalgia and are associated with different severity depression conditions.

Evaluation of a Hyperbaric Oxygen Therapy Intervention in Individuals with Fibromyalgia

OBJECTIVE

To evaluate the feasibility and safety of hyperbaric oxygen therapy (HBOT) in patients with fibromyalgia (FM).

DESIGN

A cohort study with a delayed treatment arm used as a comparator.

SETTING

Hyperbaric Medicine Unit, Toronto General Hospital, Ontario, Canada.

SUBJECTS

Eighteen patients diagnosed with FM according to the American College of Rheumatology and a score ≥60 on the Revised Fibromyalgia Impact Questionnaire.

METHODS

Participants were randomized to receive immediate HBOT intervention (n = 9) or HBOT after a 12-week waiting period (n = 9). HBOT was delivered at 100% oxygen at 2.0 atmospheres per session, 5 days per week, for 8 weeks. Safety was evaluated by the frequency and severity of adverse effects reported by patients. Feasibility was assessed by recruitment, retention, and HBOT compliance rates. Both groups were assessed at baseline, after HBOT intervention, and at 3 months' follow-up. Validated assessment tools were used to evaluate pain, psychological variables, fatigue, and sleep quality.

RESULTS

A total of 17 patients completed the study. One patient withdrew after randomization. HBOT-related adverse events included mild middle-ear barotrauma in three patients and new-onset myopia in four patients. The efficacy of HBOT was evident in most of the outcomes in both groups. This improvement was sustained at 3-month follow-up assessment.

CONCLUSION

HBOT appears to be feasible and safe for individuals with FM. It is also associated with improved global functioning, reduced symptoms of anxiety and depression, and improved quality of sleep that was sustained at 3-month follow-up assessment.

Association of core body temperature and peripheral blood flow of the hands with pain intensity, pressure pain hypersensitivity, central sensitization, and fibromyalgia symptoms

Our aim was to analyse body core temperature and peripheral vascular microcirculation at skin hypothenar eminence of the hands and its relationship to symptoms in fibromyalgia syndrome (FMS). A total of 80 FMS women and 80 healthy women, matched on weight, were enrolled in this case-control study. Thermography and infrared thermometer were used for evaluating the hypothenar regions and core body temperature, respectively. The main outcome measures were pain pressure thresholds (PPTs) and clinical questionnaires. Significant associations were observed between overall impact [β = 0.033; 95% confidence interval (95%CI) = 0.003, 0.062; p = 0.030], daytime dysfunction (β = 0.203; 95%CI = 0.011, 0.395; p = 0.039) and reduced activity (β = 0.045; 95%CI = 0.005, 0.085; p = 0.029) and core body temperature in FMS women. PPTs including greater trochanter dominant (β = 0.254; 95%CI = 0.003, 0.504; p = 0.047), greater trochanter non-dominant (β = 0.650; 95%CI = 0.141, 1.159; p = 0.013), as well as sleeping medication (β = -0.242; 95%CI = -0.471, -0.013; p = 0.039) were also associated with hypothenar eminence temperature. Data highlighted that FMS women showed correlations among body core temperature and hand temperature with the clinical symptoms.

A Systematic Review Into the Influence of Temperature on Fibromyalgia Pain: Meteorological Studies and Quantitative Sensory Testing

Fibromyalgia syndrome (FMS) is a chronic widespread pain condition of unknown aetiology. The role of temperature in FMS pain has not been reviewed systematically. The goal of this study was to review the influences of temperature on pain in FMS, from meteorological and quantitative sensory testing (QST) studies. The review was registered with Prospero: ID-CRD42020167687, and followed PRISMA guidance. Databases interrogated were: MEDLINE (via OVID), EMBASE, PubMed, Web of Science, ScienceDirect, CINAHL, and ProQuest (Feb'20). Exclusion criteria were: age <18, animal studies, non-English, and noncontrolled articles. Thirteen studies pertaining to ambient temperature and FMS pain were identified; 9 of these found no uniform relationship. Thirty-five QST studies were identified, 17 of which assessed cold pain thresholds (CPTs). All studies showed numerically reduced CPTs in patients, ranging from 10.9°C to 26.3°C versus 5.9°C to 13.5°C in controls; this was statistically significant in 14/17. Other thermal thresholds were often abnormal. We conclude that the literature provides consistent evidence for an abnormal sensitization of FMS patients' temperature-sensation systems. Additional work is required to elucidate the factors that determine why a subgroup of patients perceive low ambient temperatures as painful, and to characterize that group. PERSPECTIVE: Patients often report increased pain with changes in ambient temperature; even disabling, extreme temperature sensitivity in winter. Understanding this phenomenon may help clinicians provide reassurance and advice to patients and may guide research into the everyday impact of such hypersensitivity, whilst directing future work into the pathophysiology of FMS.

Reduced activity, reactivity and functionality of the sympathetic nervous system in fibromyalgia: An electrodermal study

Alterations in autonomic activity are well established in fibromyalgia syndrome (FMS). Previous studies found reduced parasympathetic activity and sympathetic reactivity to physical and stress manipulations. However, sympathetic activity at rest has not been well studied in FMS. Sweating is exclusively controlled by sympathetic mechanisms. In this study, skin conductance (SC), as an indirect measure of sweating, was analyzed in 45 women with FMS and 38 healthy women. Tonic SC levels were recorded during a 4-minute rest period, and a breathing maneuver consisting of deep breathing with posterior breath holding was used to evoke SC responses. Associations of tonic SC with state anxiety and body temperature, measured in the hand, were explored to determine sweat functionality. The results showed reduced tonic SC levels, with a less marked decrease in SC during the recording period, and blunted SC reactivity to the breathing manipulation in FMS patients relative to healthy participants. Positive associations of SC with state anxiety and body temperature were observed in healthy participants, but these associations were absent in FMS patients. These results indicate alterations of sweating in FMS, suggesting reduced tonic and reactivity sympathetic influences. Furthermore, the absence of associations between SC levels and state anxiety and body temperature in the patient sample suggested a loss of functionality of the autonomic nervous system in FMS. Diminished autonomic regulation in FMS would reduce the ability to cope with environmental demands, thus favoring increases in stress and pain levels. Finally, the observed reduction in sweating is in accordance with evidence of small nerve fiber neuropathy in FMS.

Intramuscular Pressure Is Almost Three Times Higher in Fibromyalgia Patients: A Possible Mechanism for Understanding the Muscle Pain and Tenderness

OBJECTIVE

Widespread pain in fibromyalgia syndrome (FMS) is conventionally viewed as arising from disordered central processing. This study examines intramuscular pressure in the trapezius as an alternative mechanism for understanding FMS pain.

METHODS

One hundred eight patients who satisfied the American College of Rheumatology criteria for FMS and 30 patients who met the ACR criteria for another rheumatic disease comprised the study groups. Muscle pressure was measured in mmHg using a pressure gauge attached to a no. 22 needle inserted into the mid-portion of the trapezius muscle. In addition, patients with FMS and rheumatic disease controls had dolorimetry testing, digital palpation, and reported pain scores.

RESULTS

Muscle pressure was substantially higher in patients with FMS with a mean value of 33.48 ± 5.90 mmHg. Only 2 of 108 patients had muscle pressure of < 23 mmHg. The mean pressure in rheumatic disease controls was 12.23 ± 3.75 mmHg, with a range from 3-22 mmHg. Patients with FMS were more tender than controls based on both dolorimetry (P < 0.001) and digital palpation (P < 0.001). The mean pain score in patients with FMS and controls was 6.68 ± 1.91 and 1.43 ± 1.79, respectively (P < 0.001).

CONCLUSION

Pressure in the trapezius muscle of patients with FMS is remarkably elevated and may be an intrinsic feature of FMS that could be monitored as part of the diagnostic evaluation. The burden of the pressure abnormality may help explain the diffuse muscle pain of FMS. Therefore, FMS as a disorder of exclusively central pain processing should be revisited. Therapeutically, the reduction of muscle pressure may change the clinical picture significantly.

Force-time curve features of handgrip strength in fibromyalgia syndrome

The aim of this study was to compare the handgrip strength (HGs), assessed with a cylindrical-shape grip device, of fibromyalgia syndrome (FM) patients with healthy subjects and to demonstrate the relationship between HGs characteristics and disease severity. Consecutive female patients with FM were enrolled and compared to a group of healthy women. The correlations between HGs curve characteristics and disease severity indices were studied through the Spearman’s rho correlation coefficients (rho). The HGs threshold distinguishing the FM presence was determined using the receiver operating characteristic (ROC) curves analysis. Multivariate regression analysis was used in order to assess the contribution of covariates on the HGs. 110 patients (mean age 53.8 ± 12.4 years) and 111 healthy controls have been enrolled. Altogether all parameters related to the analysis of HGs were worse in patients with FM. The HGs cut-off distinguishing the presence of a FM was 14.2 Kg. A negative correlation was found between disease severity indices and peak force (p < 0.001). Factors significantly associated with HGs area under the curve (AUC) in multivariate analysis were the Widespread Pain Index (WPI) (p = 0.003) and the revised Fibromyalgia Impact Questionnaire (FIQR) (p = 0.016). HGs is reduced in female FM patients and is inversely related to disease severity. The force-time curves analysis may be used as a complementary tool in the FM assessment and monitoring.

Interleukin 1β inhibition contributes to the antinociceptive effects of voluntary exercise on ischemia/reperfusion-induced hypersensitivity

Issues of peripheral circulation have been increasingly suggested as an underlying cause of musculoskeletal pain in many conditions, including sickle cell anemia and peripheral vascular disease. We have previously shown in our model of transient ischemia and reperfusion (I/R) injury of the forelimb that individual group III and IV muscle afferents display altered chemosensitivity and mechanical thresholds 1 day after injury. Functional alterations corresponded to increased evoked and spontaneous pain-related behaviors and decreased muscle strength and voluntary activity-all actions that echo clinical symptoms of ischemic myalgia. These behavioral and physiological changes appeared to originate in part from the action of increased interleukin 1β (IL1β) in the injured muscles at its upregulated IL1 receptor 1 within the dorsal root ganglion. Here, we describe that two days of voluntary wheel running prior to I/R blocks both injury-induced IL1β enhancement and the subsequent development of ischemic myalgia-like behaviors. Furthermore, the protective effects of 2 days prior exercise on the I/R-evoked increases in pain-related behaviors were also paralleled with systemic injection of the IL1 receptor antagonist during I/R. Interleukin 1 receptor antagonist treatment additionally prevented the I/R-induced changes in mechanical and chemical sensitivity of individual primary muscle afferents. Altogether, these data strengthen the evidence that transient I/R injury sensitizes group III and IV muscle afferents via increased IL1β in the muscles to stimulate ischemic myalgia development. Targeting IL1β may, therefore, be an effective treatment strategy for this insidious type of muscle pain.

Association of physical fitness components and health-related quality of life in women with systemic lupus erythematosus with mild disease activity

OBJECTIVES

To study the association of different components of physical fitness [flexibility, muscle strength and cardiorespiratory fitness (CRF)] and a clustered fitness score with health-related quality of life (HRQoL) in women with systemic lupus erythematosus (SLE) and to analyze whether participants with high fitness level have better HRQoL.

METHODS

This cross-sectional study included 70 women with SLE (aged 42.5; SD 13.9 years). The back-scratch test assessed flexibility, the 30-sec chair stand and handgrip strength tests assessed muscle strength, and the 6-min walk test (n = 49) assessed CRF. HRQoL was assessed through the 36-item Short-Form Health Survey (SF-36).

RESULTS

Flexibility was positively associated with the physical function dimension and the physical component summary (PCS) (rpartial between 0.26 and 0.31; p<0.05), and negatively related with social functioning dimension (rpartial = -0.26; p<0.05). Muscle strength was positively associated with the physical function, physical role, bodily pain dimensions and the PCS (rpartial between 0.27 and 0.49; all p<0.05). CRF was positively associated with the physical function and bodily pain dimensions, and PCS (rpartial between 0.39 and 0.65; all p<0.05). The clustered fitness score was associated with the physical function (B = 17.16) and bodily pain (B = 14.35) dimensions, and the PCS (B = 6.02), all p<0.005. Patients with high fitness level had greater scores in the physical function, physical role, and bodily pain dimensions and the PCS, all p≤0.05.

CONCLUSIONS

Our study suggests that muscle strength and CRF are positively associated with HRQoL, while flexibility showed contradictory results. These findings highlight the importance of maintaining adequate fitness levels in women with SLE.

Fascial preadipocytes: another missing piece of the puzzle to understand fibromyalgia?

Fibromyalgia (FM) syndrome is a chronic condition causing pain, affecting approximately 0.5%-6% of the developed countries' population, and on average, 2% of the worldwide population. Despite the large amount of scientific literature available, the FM etiology is still uncertain. The diagnosis is based on the clinical presentation and the severity of the symptomatology. Several studies pointed out pathological alterations within the central nervous system, suggesting that FM could originate from a central sensitization of the pain processing centers. Research supports the thesis of a peripheral neuropathic component, with the finding of axonal damages. The fibromyalgia patient has many myofascial system abnormalities, such as pain and fatigue, impairing the symptomatic profile. This paper revises the myopathic compensations, highlighting the possible role of the fascia in generating symptoms, being aware of the new information about the fascia's activity in stimulating inflammation and fat cell production.

Sex differences in primary muscle afferent sensitization following ischemia and reperfusion injury

BACKGROUND

Chronic pain conditions are more prevalent in women, but most preclinical studies into mechanisms of pain generation are performed using male animals. Furthermore, whereas group III and IV nociceptive muscle afferents provoke central sensitization more effectively than their cutaneous counterparts, less is known about this critical population of muscle nociceptors. Here, we compare the physiology of individual muscle afferents in uninjured males and females. We then characterize the molecular, physiological, and behavioral effects of transient ischemia and reperfusion injury (I/R), a model we have extensively studied in males and in females.

METHODS

Response properties and phenotypes to mechanical, thermal, and chemical stimulation were compared using an ex vivo muscle/nerve/dorsal root ganglia (DRG)/spinal cord recording preparation. Analyses of injury-related changes were also performed by assaying evoked and spontaneous pain-related behaviors, as well as mRNA expression of the affected muscle and DRGs. The appropriate analyses of variance and post hoc tests (with false discovery rate corrections when needed) were performed for each measure.

RESULTS

Females have more mechanically sensitive muscle afferents and show greater mechanical and thermal responsiveness than what is found in males. With I/R, both sexes show fewer cells responsive to an innocuous metabolite solution (ATP, lactic acid, and protons), and lower mechanical thresholds in individual afferents; however, females also possess altered thermal responsiveness, which may be related to sex-dependent changes in gene expression within the affected DRGs. Regardless, both sexes show similar increases in I/R-induced pain-like behaviors.

CONCLUSIONS

Here, we illustrate a unique phenomenon wherein discrete, sex-dependent mechanisms of primary muscle afferent sensitization after ischemic injury to the periphery may underlie similar behavioral changes between the sexes. Furthermore, although the group III and IV muscle afferents are fully developed functionally, the differential mechanisms of sensitization manifest prior to sexual maturity. Hence, this study illustrates the pressing need for further exploration of sex differences in afferent function throughout the lifespan for use in developing appropriately targeted pain therapies.

Peripheral Mechanisms of Ischemic Myalgia

Musculoskeletal pain due to ischemia is present in a variety of clinical conditions including peripheral vascular disease (PVD), sickle cell disease (SCD), complex regional pain syndrome (CRPS), and even fibromyalgia (FM). The clinical features associated with deep tissue ischemia are unique because although the subjective description of pain is common to other forms of myalgia, patients with ischemic muscle pain often respond poorly to conventional analgesic therapies. Moreover, these patients also display increased cardiovascular responses to muscle contraction, which often leads to exercise intolerance or exacerbation of underlying cardiovascular conditions. This suggests that the mechanisms of myalgia development and the role of altered cardiovascular function under conditions of ischemia may be distinct compared to other injuries/diseases of the muscles. It is widely accepted that group III and IV muscle afferents play an important role in the development of pain due to ischemia. These same muscle afferents also form the sensory component of the exercise pressor reflex (EPR), which is the increase in heart rate and blood pressure (BP) experienced after muscle contraction. Studies suggest that afferent sensitization after ischemia depends on interactions between purinergic (P2X and P2Y) receptors, transient receptor potential (TRP) channels, and acid sensing ion channels (ASICs) in individual populations of peripheral sensory neurons. Specific alterations in primary afferent function through these receptor mechanisms correlate with increased pain related behaviors and altered EPRs. Recent evidence suggests that factors within the muscles during ischemic conditions including upregulation of growth factors and cytokines, and microvascular changes may be linked to the overexpression of these different receptor molecules in the dorsal root ganglia (DRG) that in turn modulate pain and sympathetic reflexes. In this review article, we will discuss the peripheral mechanisms involved in the development of ischemic myalgia and the role that primary sensory neurons play in EPR modulation.

Muscle IL1β Drives Ischemic Myalgia via ASIC3-Mediated Sensory Neuron Sensitization

Musculoskeletal pain is a significantly common clinical complaint. Although it is known that muscles are quite sensitive to alterations in blood flow/oxygenation and a number of muscle pain disorders are based in problems of peripheral perfusion, the mechanisms by which ischemic-like conditions generate myalgia remain unclear. We found, using a multidisciplinary experimental approach, that ischemia and reperfusion injury (I/R) in male Swiss Webster mice altered ongoing and evoked pain-related behaviors in addition to activity levels through enhanced muscle interleukin-1 beta (IL1β)/IL1 receptor signaling to group III/IV muscle afferents. Peripheral sensitization depended on acid-sensing ion channels (ASICs) because treatment of sensory afferents in vitro with IL1β-upregulated ASIC3 in single cells, and nerve-specific knock-down of ASIC3 recapitulated the results of inhibiting the enhanced IL1β/IL1r1 signaling after I/R, which was also found to regulate afferent sensitization and pain-related behaviors. This suggests that targeting muscle IL1β signaling may be a potential analgesic therapy for ischemic myalgia.

SIGNIFICANCE STATEMENT

Here, we have described a novel pathway whereby increased inflammation within the muscle tissue during ischemia/reperfusion injury sensitizes group III and IV muscle afferents via upregulation of acid-sensing ion channel 3 (ASIC3), leading not only to alterations in mechanical and chemical responsiveness in individual afferents, but also to pain-related behavioral changes. Furthermore, these I/R-induced changes can be prevented using an afferent-specific siRNA knock-down strategy targeting either ASIC3 or the upstream mediator of its expression, interleukin 1 receptor 1. Therefore, this knowledge may contribute to the development of alternative therapeutics for muscle pain and may be especially relevant to pain caused by issues of peripheral circulation, which is commonly observed in disorders such as complex regional pain syndrome, sickle cell anemia, or fibromyalgia.

Fibromyalgia: A Critical and Comprehensive Review

Fibromyalgia is a disorder that is part of a spectrum of syndromes that lack precise classification. It is often considered as part of the global overview of functional somatic syndromes that are otherwise medically unexplained or part of a somatization disorder. Patients with fibromyalgia share symptoms with other functional somatic problems, including issues of myalgias, arthralgias, fatigue and sleep disturbances. Indeed, there is often diagnostic and classification overlap for the case definitions of a variety of somatization disorders. Fibromyalgia, however, is a critically important syndrome for physicians and scientists to be aware of. Patients should be taken very seriously and provided optimal care. Although inflammatory, infectious, and autoimmune disorders have all been ascribed to be etiological events in the development of fibromyalgia, there is very little data to support such a thesis. Many of these disorders are associated with depression and anxiety and may even be part of what has been sometimes called affected spectrum disorders. There is no evidence that physical trauma, i.e., automobile accidents, is associated with the development or exacerbation of fibromyalgia. Treatment should be placed on education, patient support, physical therapy, nutrition, and exercise, including the use of drugs that are approved for the treatment of fibromyalgia. Treatment should not include opiates and patients should not become poly pharmacies in which the treatment itself can lead to significant morbidities. Patients with fibromyalgia are living and not dying of this disorder and positive outlooks and family support are key elements in the management of patients.

Fibromyalgia syndrome pathology and environmental influences on afflictions with medically unexplained symptoms

Fibromyalgia syndrome (FMS) is a clinical disorder predominant in females with unknown etiology and medically unexplained symptoms (MUS), similar to other afflictions, including irritable bowel syndrome (IBS), chronic fatigue syndrome (CFS), post-traumatic stress disorder (PTSD), Gulf War illness (GFI), and others. External environmental stimuli drive behavior and impact physiologic homeostasis (internal environment) via autonomic functioning. These environments directly impact the individual affective state (mind), which feeds back to regulate physiology (body). FMS has emerged as a complex disorder with pathologies identified among neurotransmitter and enzyme levels, immune/cytokine functionality, cortical volumes, cutaneous innervation, as well as an increased frequency among people with a history of traumatic and/or emotionally negative events, and specific personality trait profiles. Yet, quantitative physical evidence of pathology or disease etiology among FMS has been limited (as with other afflictions with MUS). Previously, our group published findings of increased peptidergic sensory innervation associated with the arterio-venous shunts (AVS) in the glabrous hand skin of FMS patients, which provides a plausible mechanism for the wide-spread FMS symptomology. This review focuses on FMS as a model affliction with MUS to discuss the implications of the recently discovered peripheral innervation alterations, explore the role of peripheral innervation to central sensitization syndromes (CSS), and examine possible estrogen-related mechanisms through which external and internal environmental factors may contribute to FMS etiology and possibly other afflictions with MUS.

Food intake assessment and quality of life in women with fibromyalgia

OBJECTIVE

To compare the food intake of women with and without fibromyalgia and verify if the food intake of patients with fibromyalgia interferes with the pain and quality of life.

METHODS

Study participants were women with fibromyalgia (FM) seen in Fibromyalgia Outpatient Clinic, Hospital das Clínicas/UFPR and a control group (CT) with healthy women. Data collection was conducted from March to October 2012. For the assessment of food intake we used the Food Registration and the analyzed items were total calories, carbohydrates, proteins, lipids, vitamins (A, C, B12, D and E) and minerals (folate, selenium, zinc, iron, calcium and magnesium). The software used was Avanutri Online(®). To evaluate the quality of life, the Fibromyalgia Impact Questionnaire (FIQ) and pain threshold were used.

RESULTS

43 patients with FM and 44 healthy women were evaluated. CT group showed a mean consumption of nutrients greater than FM group except for iron. However, only caloric intake, carbohydrates, proteins and lipids in grams and percentage of lipids, vitamin A, E, B12, folate, selenium and calcium were statistically significant. In FM group, there was a negative correlation between vitamin E and FIQ and a positive correlation between percentage of protein and pain threshold.

CONCLUSION

Women with FM showed a lower qualitative and quantitative intake in comparison with CT group. Only vitamin E correlated with quality of life and percentage of protein in the diet with sensation of pain.

Nitric Oxide, Inflammation, Lipid Profile, and Cortisol in Normal- and Overweight Women With Fibromyalgia

Objectives:

Research has identified many factors associated with fibromyalgia (FM), but findings have been inconsistent. This study aimed to investigate changes in levels of nitric oxide (NO), inflammatory markers, lipid profile, and cortisol in normal- and overweight patients with FM and controls. Since most patients with FM are overweight, we explored possible changes in these markers according to body mass index (BMI).

Methods:

This preliminary study was performed on serum samples of women with FM and age-matched controls, grouped according to their BMI: 12 normal-weight patients and 12 controls and 13 overweight patients and 8 controls. Ozone-based chemiluminescence assay was used to measure NO. Inflammatory mediators and cortisol were determined by immunoassay. Lipid profile was measured by a spectrophotometric procedure. Functional capacity was assessed by the fibromyalgia impact questionnaire (FIQ).

Results:

Normal-weight patients showed higher levels of C-reactive protein (CRP) and apolipoprotein B compared to controls (both p < .05). CRP, apolipoprotein B, and triglycerides were higher in overweight patients versus overweight controls (all p < .05) and in overweight versus normal-weight patients (CRP p < .01; apolipoprotein B, triglycerides p < .05). The other markers were unaffected. Apolipoprotein B ( r = .762; p < .05) and NO ( r = −.921; p < .05) levels correlated with FIQ score in normal-weight patients. CRP level correlated with FIQ ( r = .912; p < .05) in overweight patients.

Conclusions:

CRP and apolipoprotein B, biomarkers linked to cardiovascular events, may be associated with FM-related dysfunction in normal- and overweight women with FM. Their increased levels in these patients may indicate an increased risk of cardiovascular disease.

Effects of 12-week combined exercise therapy on oxidative stress in female fibromyalgia patients

The aims of this study were to investigate the effect of exercise therapy on the oxidative stress in fibromyalgia patients and relationship between oxidative stress and fibromyalgia symptoms. Thirty women diagnosed with fibromyalgia according to the American College of Rheumatology preliminary criteria, and 23 healthy women whose age- and weight-matched women were enrolled the study. Pain intensity with visual analog scale (VAS), the number of tender points, the fibromyalgia impact questionnaire (FIQ), the Beck depression inventory (BDI) were evaluated. The oxidative stress parameters thiobarbituric acid reactive substances, protein carbonyls, and nitric oxide, and antioxidant parameters thiols and catalase were investigated in patients and control group. After, combined aerobic and strengthen exercise regimen was given to fibromyalgia group. Exercise therapy consisted of a warming period of 10 min, aerobic exercises period of 20 min, muscle strengthening exercises for 20 min, and 10 min cooling down period. Therapy was lasting 1 h three times per week over a 12-week period. All parameters were reevaluated after the treatment in the patient group. The oxidative stress parameters levels were significantly higher, and antioxidant parameters were significantly lower in patients with fibromyalgia than in the controls. VAS, FIQ, and BDI scores decreased significantly with exercise therapy. The exercise improved all parameters of oxidative stress and antioxidant parameters. Also, all clinical parameters were improved with exercise. We should focus on oxidative stress in the treatment for fibromyalgia with the main objective of reducing oxidative load.

Fibromyalgia

Fibromyalgia is a chronic pain condition present in 2-4% of the population. Fibromyalgia consists of widespread pain with similarities to neuropathic pain in clinical findings, pathophysiology, and neuropharmacology. Pain is the predominant symptom and allodynia and hyperalgesia are common signs. Extreme fatigue, impaired cognition and nonrestorative sleep difficulties coexist in addition to other somatic symptoms. Research including neuroimaging investigations shows abnormalities in neurotransmitters and an abnormal response to pain. Altered pain processing peripherally and centrally contribute to central sensitization and a dampened effect of the diffuse noxious inhibitory control (DNIC). Successful management incorporates education of the patient in self-management skills, cognitive behavioral therapy (CBT), exercise, and drug therapy. Tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors (SNRIs) (duloxetine and milnacipran), α2-δ ligands (gabapentin and pregabalin) are effective in reducing pain by≥30%. Some success has been shown with dopamine agonists (pramipexole), tramadol, other opioids and cannabinoids (nabilone). Further evidence-based trials using complementary treatments are needed. Fibromyalgia is complex and requires a multidisciplinary approach to treatment. Patient self-management is key.

Excessive peptidergic sensory innervation of cutaneous arteriole-venule shunts (AVS) in the palmar glabrous skin of fibromyalgia patients: implications for widespread deep tissue pain and fatigue

OBJECTIVE

To determine if peripheral neuropathology exists among the innervation of cutaneous arterioles and arteriole-venule shunts (AVS) in fibromyalgia (FM) patients.

SETTING

Cutaneous arterioles and AVS receive a convergence of vasoconstrictive sympathetic innervation, and vasodilatory small-fiber sensory innervation. Given our previous findings of peripheral pathologies in chronic pain conditions, we hypothesized that this vascular location may be a potential site of pathology and/or serotonergic and norepinephrine reuptake inhibitors (SNRI) drug action.

SUBJECTS

Twenty-four female FM patients and nine female healthy control subjects were enrolled for study, with 14 additional female control subjects included from previous studies. AVS were identified in hypothenar skin biopsies from 18/24 FM patient and 14/23 control subjects.

METHODS

Multimolecular immunocytochemistry to assess different types of cutaneous innervation in 3 mm skin biopsies from glabrous hypothenar and trapezius regions.

RESULTS

AVS had significantly increased innervation among FM patients. The excessive innervation consisted of a greater proportion of vasodilatory sensory fibers, compared with vasoconstrictive sympathetic fibers. In contrast, sensory and sympathetic innervation to arterioles remained normal. Importantly, the sensory fibers express α2C receptors, indicating that the sympathetic innervation exerts an inhibitory modulation of sensory activity.

CONCLUSIONS

The excessive sensory innervation to the glabrous skin AVS is a likely source of severe pain and tenderness in the hands of FM patients. Importantly, glabrous AVS regulate blood flow to the skin in humans for thermoregulation and to other tissues such as skeletal muscle during periods of increased metabolic demand. Therefore, blood flow dysregulation as a result of excessive innervation to AVS would likely contribute to the widespread deep pain and fatigue of FM. SNRI compounds may provide partial therapeutic benefit by enhancing the impact of sympathetically mediated inhibitory modulation of the excess sensory innervation.

Association of fibromyalgia with altered skeletal muscle characteristics which may contribute to postexertional fatigue in postmenopausal women

OBJECTIVE

To identify muscle physiologic properties that may contribute to postexertional fatigue and malaise in women with fibromyalgia (FM).

METHODS

Healthy postmenopausal women with (n = 11) and without (n = 11) FM, ages 51-70 years, participated in this study. Physical characteristics and responses to self-reported questionnaires were evaluated. Strength loss and tissue oxygenation in response to a fatiguing exercise protocol were used to quantify fatigability and the local muscle hemodynamic profile. Muscle biopsies were performed to assess between-group differences in baseline muscle properties using histochemical, immunohistochemical, and electron microscopic analyses.

RESULTS

There was no significant difference between healthy controls and FM patients in muscle fatigue in response to exercise. However, self-reported fatigue and pain were correlated with prolonged loss of strength following 12 minutes of recovery in patients with FM. Although there was no difference in percent succinate dehydrogenase (SDH)-positive (type I) and SDH-negative (type II) fibers or in mean fiber cross-sectional area between groups, FM patients exhibited greater variability in fiber size and altered fiber size distribution. In healthy controls only, fatigue resistance was strongly correlated with the size of SDH-positive fibers and hemoglobin oxygenation. In contrast, FM patients with the highest percentage of SDH-positive fibers recovered strength most effectively, and this was correlated with capillary density. However, overall, capillary density was lower in the FM group.

CONCLUSION

Peripheral mechanisms, i.e., altered muscle fiber size distribution and decreased capillary density, may contribute to postexertional fatigue in FM. Understanding of these defects in fibromyalgic muscle may provide valuable insight with regard to treatment.

Fibromyalgia syndrome: etiology, pathogenesis, diagnosis, and treatment

Fibromyalgia syndrome is mainly characterized by pain, fatigue, and sleep disruption. The etiology of fibromyalgia is still unclear: if central sensitization is considered to be the main mechanism involved, then many other factors, genetic, immunological, and hormonal, may play an important role. The diagnosis is typically clinical (there are no laboratory abnormalities) and the physician must concentrate on pain and on its features. Additional symptoms (e.g., Raynaud's phenomenon, irritable bowel disease, and heat and cold intolerance) can be associated with this condition. A careful differential diagnosis is mandatory: fibromyalgia is not a diagnosis of exclusion. Since 1990, diagnosis has been principally based on the two major diagnostic criteria defined by the ACR. Recently, new criteria have been proposed. The main goals of the treatment are to alleviate pain, increase restorative sleep, and improve physical function. A multidisciplinary approach is optimal. While most nonsteroidal anti-inflammatory drugs and opioids have limited benefit, an important role is played by antidepressants and neuromodulating antiepileptics: currently duloxetine (NNT for a 30% pain reduction 7.2), milnacipran (NNT 19), and pregabalin (NNT 8.6) are the only drugs approved by the US Food and Drug Administration for the treatment of fibromyalgia. In addition, nonpharmacological treatments should be associated with drug therapy.

Noninvasive optical characterization of muscle blood flow, oxygenation, and metabolism in women with fibromyalgia

Introduction

Women with fibromyalgia (FM) have symptoms of increased muscular fatigue and reduced exercise tolerance, which may be associated with alterations in muscle microcirculation and oxygen metabolism. This study used near-infrared diffuse optical spectroscopies to noninvasively evaluate muscle blood flow, blood oxygenation and oxygen metabolism during leg fatiguing exercise and during arm arterial cuff occlusion in post-menopausal women with and without FM.

Methods

Fourteen women with FM and twenty-three well-matched healthy controls participated in this study. For the fatiguing exercise protocol, the subject was instructed to perform 6 sets of 12 isometric contractions of knee extensor muscles with intensity steadily increasing from 20 to 70% maximal voluntary isometric contraction (MVIC). For the cuff occlusion protocol, forearm arterial blood flow was occluded via a tourniquet on the upper arm for 3 minutes. Leg or arm muscle hemodynamics, including relative blood flow (rBF), oxy- and deoxy-hemoglobin concentration ([HbO₂] and [Hb]), total hemoglobin concentration (THC) and blood oxygen saturation (StO₂), were continuously monitored throughout protocols using a custom-built hybrid diffuse optical instrument that combined a commercial near-infrared oximeter for tissue oxygenation measurements and a custom-designed diffuse correlation spectroscopy (DCS) flowmeter for tissue blood flow measurements. Relative oxygen extraction fraction (rOEF) and oxygen consumption rate (rVO₂) were calculated from the measured blood flow and oxygenation data. Post-manipulation (fatiguing exercise or cuff occlusion) recovery in muscle hemodynamics was characterized by the recovery half-time, a time interval from the end of manipulation to the time that tissue hemodynamics reached a half-maximal value.

Results

Subjects with FM had similar hemodynamic and metabolic response/recovery patterns as healthy controls during exercise and during arterial occlusion. However, tissue rOEF during exercise in subjects with FM was significantly lower than in healthy controls, and the half-times of oxygenation recovery (Δ[HbO₂] and Δ[Hb]) were significantly longer following fatiguing exercise and cuff occlusion.

Conclusions

Our results suggest an alteration of muscle oxygen utilization in the FM population. This study demonstrates the potential of using combined diffuse optical spectroscopies (i.e., NIRS/DCS) to comprehensively evaluate tissue oxygen and flow kinetics in skeletal muscle.

A Mechanism-Based Approach to Prevention of and Therapy for Fibromyalgia

Fibromyalgia syndrome (FMS) is characterized by pain referred to deep tissues. Diagnosis and treatment of FMS are complicated by a variable coexistence with regional pain, fatigue, sleep disruption, difficulty with mentation, and depression. The widespread, deep pain of FMS can be a consequence of chronic psychological stress with autonomic dysregulation. Stress acts centrally to facilitate pain and acts peripherally, via sympathetic vasoconstriction, to establish painful muscular ischemia. FMS pain, with or without a coexistent regional pain condition, is stressful, setting up a vicious circle of reciprocal interaction. Also, stress interacts reciprocally with systems of control over depression, mentation, and sleep, establishing FMS as a multiple-system disorder. Thus, stress and the ischemic pain it generates are fundamental to the multiple disorders of FMS, and a therapeutic procedure that attenuates stress and peripheral vasoconstriction should be highly beneficial for FMS. Physical exercise has been shown to counteract peripheral vasoconstriction and to attenuate stress, depression, and fatigue and improve mentation and sleep quality. Thus, exercise can interrupt the reciprocal interactions between psychological stress and each of the multiple-system disorders of FMS. The large literature supporting these conclusions indicates that exercise should be considered strongly as a first-line approach to FMS therapy.

Functional capacity, muscle strength and falls in women with fibromyalgia

BACKGROUND

Patients with fibromyalgia have difficulty with activities of daily living, they exhibit reduced muscle strength and high incidence of reported falls. The objective of this study was to evaluate the functional performance and lower limb muscle strength in women with fibromyalgia and determine the relationship between muscle strength and falls.

METHODS

Sixteen females with fibromyalgia and 16 healthy women participated in the study. Pain intensity, fibromyalgia impact on quality of life, physical activity level and fall prevalence were assessed. The peak torque and the rate of torque development were determined in maximal voluntary isometric contraction (hip, knee and ankle joints) using a load cell. The 30s chair stand, 8 ft up and go, sit and reach, and functional reach tests were used to characterize functional performance.

FINDINGS

Women with fibromyalgia showed deficits in lower limb muscle strength, balance and agility and exhibited decreased knee extension peak torque and rate of torque development. In addition, they showed lower hip adduction and extension peak torque in comparison to the control group (P>0.05). Hip extension rate of torque development, duration of fibromyalgia symptoms, overall pain, knee pain, and fibromyalgia impact were strong predictors of the number of falls in patients with fibromyalgia (R2=0.86; P<0.05), when considered collectively.

INTERPRETATION

Women with fibromyalgia showed reduced functional performance and lower limb muscle strength, mostly explained by pain. There was a high prevalence of falls in this population, as explained by hip extensors rate of torque development, duration of fibromyalgia symptoms and pain.

GABAB receptors in the NTS mediate the inhibitory effect of trigeminal nociceptive inputs on parasympathetic reflex vasodilation in the rat masseter muscle

The present study was designed to examine whether trigeminal nociceptive inputs are involved in the modulation of parasympathetic reflex vasodilation in the jaw muscles. This was accomplished by investigating the effects of noxious stimulation to the orofacial area with capsaicin, and by microinjecting GABAA and GABAB receptor agonists or antagonists into the nucleus of the solitary tract (NTS), on masseter hemodynamics in urethane-anesthetized rats. Electrical stimulation of the central cut end of the cervical vagus nerve (cVN) in sympathectomized animals bilaterally increased blood flow in the masseter muscle (MBF). Increases in MBF evoked by cVN stimulation were markedly reduced following injection of capsaicin into the anterior tongue in the distribution of the lingual nerve or lower lip, but not when injected into the skin of the dorsum of the foot. Intravenous administration of either phentolamine or propranolol had no effect on the inhibitory effects of capsaicin injection on the increases of MBF evoked by cVN stimulation, which were largely abolished by microinjecting the GABAB receptor agonist baclofen into the NTS. Microinjection of the GABAB receptor antagonist CGP-35348 into the NTS markedly attenuated the capsaicin-induced inhibition of MBF increase evoked by cVN stimulation, while microinjection of the GABAA receptor antagonist bicuculline did not. Our results indicate that trigeminal nociceptive inputs inhibit vagal-parasympathetic reflex vasodilation in the masseter muscle and suggest that the activation of GABAB rather than GABAA receptors underlies the observed inhibition in the NTS.

Effects of strength vs aerobic exercise on pain severity in adults with fibromyalgia: a randomized equivalence trial

Strength training and aerobic exercise have beneficial effects on pain in adults with fibromyalgia. However, the equivalence of strengthening and aerobic exercise has not been reported. The primary aim of this randomized equivalence trial involving patients with fibromyalgia admitted to an interdisciplinary pain treatment program was to test the hypothesis that strengthening (n=36) and aerobic (n=36) exercise have equivalent effects (95% confidence interval within an equivalence margin ± 8) on pain, as measured by the pain severity subscale of the Multidimensional Pain Inventory. Secondary aims included determining the effects of strengthening and aerobic exercise on peak Vo(2) uptake, leg strength, and pressure pain thresholds. In an intent-to-treat analysis, the mean (± standard deviation) pain severity scores for the strength and aerobic groups at study completion were 34.4 ± 11.5 and 37.6 ± 11.9, respectively. The group difference was -3.2 (95% confidence interval, -8.7 to 2.3), which was within the equivalence margin of Δ8. Significant improvements in pain severity (P<.001), peak Vo(2) (P<.001), strength (P<.001), and pain thresholds (P<.001) were observed from baseline to week 3 in the intent-to-treat analysis; however, patients in the aerobic group (mean change 2.0 ± 2.6 mL/kg/min) experienced greater gains (P<.013) in peak Vo(2) compared to the strength group (mean change 0.4 ± 2.6 mL/kg/min). Knowledge of the equivalence and physiological effects of exercise have important clinical implications that could allow practitioners to target exercise recommendations on the basis of comorbid medical conditions or patient preference for a particular type of exercise. This study found that strength and aerobic exercise had equivalent effects on reducing pain severity among patients with fibromyalgia.