Clinical overlap between fibromyalgia and myalgic encephalomyelitis. A systematic review and meta-analysis

Abstract:

Introduction: Myalgic encephalomyelitis is an illness characterized by profound malaise after mental or physical effort occurring in patients already suffering from constant fatigue. On the other hand, widespread pain and widespread allodynia are the core fibromyalgia clinical features.

There is controversy on these two syndromes alikeness. Through the years, different diagnostic and/or classification criteria have been put forward to appraise both fibromyalgia and myalgic encephalomyelitis.

The epidemiology of these two illnesses, and their overlap, may vary accordingly to the used definition. The most recent Wolfe et al. 2016 fibromyalgia diagnostic criteria incorporates three myalgic encephalomyelitis features including fatigue, waking unrefreshed and dyscognition. The objective of this meta-analysis was to define the clinical overlap between fibromyalgia and myalgic encephalomyelitis based on a systematic literature review.

Methods: PubMed, Embase, Lilacs, and Cochrane data bases were searched on January 25, 2021 linking the medical subject heading “Fibromyalgia” to the following terms “chronic fatigue syndrome”, “myalgic encephalomyelitis” and “systemic exertion intolerance disease”.

Our review included all original articles in which the clinical overlap between fibromyalgia and myalgic encephalomyelitis could be quantified based on recognized diagnostic or classification criteria. Articles scrutiny and selection followed the PRISMA guidelines. Each study quality was assessed according to GRADE recommendations. The global clinical overlap was calculated using a fixed effect model with inverse variance-weighted average method.

Results: Twenty one publications were included in the meta-analysis. Reviewed studies were highly dissimilar in their design, objectives, sample size, diagnostic criteria, and/or outcomes yielding a 98% heterogeneity index.

Nevertheless, the clinical overlap between fibromyalgia and myalgic encephalomyelitis was a well defined outcome that could be reliably calculated despite the high heterogeneity value.

All reviewed publications had moderate GRADE evidence level. Most evaluated articles used the old 1990 Wolfe et al. fibromyalgia diagnostic criteria. Myalgic encephalomyelitis and fibromyalgia diagnoses overlapped in 47.3% (95% CI: 45.97-48.63) of the reported cases.

Conclusion: This meta-analysis found prominent clinical overlap between fibromyalgia and myalgic encephalomyelitis. It seems likely that this concordance would be even higher when using the most recent Wolfe et al. 2016 fibromyalgia diagnostic criteria.

Source: Ramírez-Morales R, Bermúdez-Benítez E, Martínez-Martínez LA, Martínez-Lavín M. Clinical overlap between fibromyalgia and myalgic encephalomyelitis. A systematic review and meta-analysis. Autoimmun Rev. 2022 Aug;21(8):103129. doi: 10.1016/j.autrev.2022.103129. Epub 2022 Jun 9. PMID: 35690247. https://www.sciencedirect.com/science/article/abs/pii/S1568997222000994?via%3Dihub

Evidence of neuroinflammation in fibromyalgia syndrome: a [18F]DPA-714 positron emission tomography study

Abstract:

This observational study aimed to determine whether individuals with fibromyalgia (FM) exhibit higher levels of neuroinflammation than healthy controls (HCs), as measured with positron emission tomography using [18F]DPA-714, a second-generation radioligand for the translocator protein (TSPO).
Fifteen women with FM and 10 HCs underwent neuroimaging. Distribution volume (VT) was calculated for in 28 regions of interest (ROIs) using Logan graphical analysis and compared between groups using multiple linear regressions. Group (FM vs HC) was the main predictor of interest and TSPO binding status (high- vs mixed-affinity) was added as a covariate. The FM group had higher VT in the right postcentral gyrus (b = 0.477, P = 0.033), right occipital gray matter (GM; b = 0.438, P = 0.039), and the right temporal GM (b = 0.466, P = 0.042). The FM group also had lower VT than HCs in the left isthmus of the cingulate gyrus (b = −0.553, P = 0.014).
In the subgroup of high-affinity binders, the FM group had higher VT in the bilateral precuneus, postcentral gyrus, parietal GM, occipital GM, and supramarginal gyrus. Group differences in the right parietal GM were associated with decreased quality of life, higher pain severity and interference, and cognitive problems.
In support of our hypothesis, we found increased radioligand binding (VT) in the FM group compared with HCs in several brain regions regardless of participants’ TSPO binding status. The ROIs overlapped with prior reports of increased TSPO binding in FM. Overall, increasing evidence supports the hypothesis that FM involves microglia-mediated neuroinflammation in the brain.
Source: Mueller C, Fang YD, Jones C, McConathy JE, Raman F, Lapi SE, Younger JW. Evidence of neuroinflammation in fibromyalgia syndrome: a [18F]DPA-714 positron emission tomography study. Pain. 2023 Jun 15. doi: 10.1097/j.pain.0000000000002927. Epub ahead of print. PMID: 37326674. https://pubmed.ncbi.nlm.nih.gov/37326674/

Inflammation-induced pain and fatigue in fibromyalgia and ME/CFS and role of variant connective tissue

Abstract:

Background: Fibromyalgia and ME/CFS are multifaceted conditions with overlapping symptoms(1); the pathophysiological mechanisms are under debate. It remains unclear whether dysregulated inflammation, induced either by an exogenous stimulus (eg a virus or other stressor), or autoimmunity, is of prime importance [2].

Objectives: 1. To determine in a novel human model the effects of an in vivo inflammatory challenge in the induction of pain and fatigue in fibromyalgia and ME/CFS compared to controls. 2. Explore potential mediators and moderators involved.

Methods: Data were available for 48 patients with confirmed diagnoses of Fibromyalgia and/ or ME/CFS and 22 matched controls, who had undergone a placebo controlled inflammatory challenge (typhoid vaccination) as part of ISRCTN78820481. Participants underwent full research diagnostic evaluation including a hypermobility assessment. Subjective pain and fatigue were assessed after saline injection and typhoid vaccination (VAS). Linear regression models were used to explore predictors, with adjustment for potential confounders (age/gender) and baseline levels as appropriate.

Mediation analyses (looking for mechanistic effects) were conducted according to the method of Hayes (3) and mediation considered significant if bootstrapped confidence intervals of the estimated indirect effect did not cross zero. In these mediation analyses predictor variable was group membership (patient or control), outcome variable was change in 1) pain and 2) fatigue induced by challenge and mediators/moderators included change in IL-6 induced by inflammatory challenge and hypermobility features.

Results: Being a patient rather than control significantly predicted inflammation-induced fatigue (B=14.89 (95%CI 3.29-26.50), t=2.56, p=0.013) and pain (B=12.88 (95%CI 0.65-25.10), t=2.11, p=0.039) after adjusting for levels induced by placebo.

Induced pain was independently predicted by level of IL-6 induced by inflammatory challenge (B=23.44 (95%CI 5.15-41.72),t=2.57, p=0.013) as was induced fatigue (B=10.63 (95%CI 2.84-18.41), t=2.73, p=0.008) Mediated moderation analyses suggested the link to induced pain and fatigue through induced inflammation was associated with hypermobility features (Index of mediated moderation 11.02 (95%CI 1.45-22.73) and 6.20 (95%CI 0.07-13.64) respectively))

Conclusion: To our knowledge this is the first human study to evaluate directly the effect of an exogenous inflammatory challenge (typhoid vaccination) in a combined group of Fibromyalgia and ME/CFS patients. Il-6 was shown to be a critical mediator. This work strongly supports the hypothesis that inflammation is key to the pathophysiology of ME/CFS. We are evaluating associated CNS inflammation in the model, as well as other associations, such as autonomic dysfunction and hypermobility. Further understanding the mediators involved in the condition should in future open the way to testing targeted anti-inflammatory therapy.

Source: Eccles J, Amato M, Themelis K, et alOP0194 INFLAMMATION-INDUCED PAIN AND FATIGUE IN FIBROMYALGIA AND ME/CFS AND ROLE OF VARIANT CONNECTIVE TISSUEAnnals of the Rheumatic Diseases 2023;82:129. https://ard.bmj.com/content/82/Suppl_1/129.2 (Full text)

Rheumatology and Long COVID: lessons from the study of fibromyalgia

Abstract:

Rheumatology, such as other subspecialties, has both a unique perspective to offer as well as an evolving role to play in the global COVID-19 pandemic. Our field has already contributed meaningfully to the development and repurposing of many of the immune-based therapeutics which are now standard treatments for severe forms of the disease as well as to the understanding of the epidemiology, risk factors and natural history of COVID-19 in immune-mediated inflammatory diseases. Still in evolution is our potential to contribute to burgeoning research efforts in the next phase of the pandemic: the syndrome of postacute sequelae of COVID-19 or Long COVID. While our field brings many assets to the study of Long COVID including our expertise in the investigation of chronic inflammation and autoimmunity, our Viewpoint focuses on the strong similarities between fibromyalgia (FM) and Long COVID. While one can speculate on how embracing and confident practising rheumatologists already are regarding these interrelationships, we assert that in the emerging field of Long COVID the potential lessons from the field of fibromyalgia care and research have been underappreciated and marginalised and most importantly now deserve a critical appraisal.

Source: Clauw DJ, Calabrese L. Rheumatology and Long COVID: lessons from the study of fibromyalgia. Ann Rheum Dis. 2023 May 25:ard-2023-224250. doi: 10.1136/ard-2023-224250. Epub ahead of print. PMID: 37230736. https://ard.bmj.com/content/early/2023/05/24/ard-2023-224250 (Full text)

Identifying Demographic Trends in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients Presenting with Fibromyalgia as a Comorbidity in the Nationwide Inpatient Sample Database

Abstract

This retrospective observational study investigates the demographic differences between Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) patients with and without Fibromyalgia as a comorbidity using the Nationwide Inpatient Sample database.

Results reveal significant differences in demographics, including a higher proportion of females and a younger mean age in the Fibromyalgia group. Additionally, the Fibromyalgia group had lower in-hospital mortality, higher proportion of patients discharged home or to short-term hospitals, shorter lengths of stay, and lower hospital charges.

Despite having lower Elixhauser comorbidity scores, ME/CFS patients with Fibromyalgia had higher prevalence of certain conditions.

Limitations include missing data, and further research is warranted to refine ME/CFS definitions and develop personalized treatment plans. The study highlights the need for better understanding of ME/CFS mechanisms, correlations with comorbidities like Fibromyalgia, and potential predictors to improve diagnosis and treatment.

Source: Arvind Vishnu Murali. Identifying Demographic Trends in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients Presenting with Fibromyalgia as a Comorbidity in the Nationwide Inpatient Sample Database. Icahn School of Medicine at Mount Sinai ProQuest Dissertations Publishing,  2023. 30494377. https://www.proquest.com/openview/12cb80c96056a220f9e1d8bd7ea5fecc/1?pq-origsite=gscholar&cbl=18750&diss=y

Influence of Chronic Fatigue Syndrome Codiagnosis on the Relationship between Perceived and Objective Psychoneuro-Immunoendocrine Disorders in Women with Fibromyalgia

Abstract:

Although the predominant symptom in fibromyalgia (FM) is muscle pain, and fatigue in chronic fatigue syndrome (CFS), differential diagnosis is very difficult. This research investigates the psychoneuroimmunoendocrine disorders of FM patients and ascertains whether a previous CFS diagnosis affected them.

Through accelerometry objective parameters, physical activity/sedentarism levels in relation to fatigue are studied, as well as whether perceived levels of stress, anxiety, and pain correspond to objective biomarkers, all of these with respect to a reference group (RG) of women without FM.

FM patients have a worse psychological state and perceived quality of life than those with RG. These perceived outcomes are consistent with impaired objective levels of a sedentary lifestyle, higher systemic levels of cortisol and noradrenaline, and lower levels of serotonin.

However, FM patients with a previous CFS diagnosis had lower systemic levels of IL-8, cortisol, oxytocin, and higher levels of adrenaline and serotonin than FM patients without diagnosed CFS.

In conclusion, while perceived health parameters do not detect differences, when objective neuroimmunoendocrine parameters related to stress, inflammation, pain, and fatigue are used, people with CFS could be overdiagnosed with FM. This reinforces the need for objective biomarker assessment of these patients for better diagnostic discrimination between both syndromes.

Source: Otero E, Gálvez I, Ortega E, Hinchado MD. Influence of Chronic Fatigue Syndrome Codiagnosis on the Relationship between Perceived and Objective Psychoneuro-Immunoendocrine Disorders in Women with Fibromyalgia. Biomedicines. 2023; 11(5):1488. https://doi.org/10.3390/biomedicines11051488 https://www.mdpi.com/2227-9059/11/5/1488 (Full text)

Neutrophils infiltrate sensory ganglia and mediate chronic widespread pain in fibromyalgia

Abstract:

Fibromyalgia is a debilitating widespread chronic pain syndrome that occurs in 2 to 4% of the population. The prevailing view that fibromyalgia results from central nervous system dysfunction has recently been challenged with data showing changes in peripheral nervous system activity.

Using a mouse model of chronic widespread pain through hyperalgesic priming of muscle, we show that neutrophils invade sensory ganglia and confer mechanical hypersensitivity on recipient mice, while adoptive transfer of immunoglobulin, serum, lymphocytes, or monocytes has no effect on pain behavior.

Neutrophil depletion abolishes the establishment of chronic widespread pain in mice. Neutrophils from patients with fibromyalgia also confer pain on mice. A link between neutrophil-derived mediators and peripheral nerve sensitization is already established. Our observations suggest approaches for targeting fibromyalgia pain via mechanisms that cause altered neutrophil activity and interactions with sensory neurons.

Source: Caxaria S, Bharde S, Fuller AM, Evans R, Thomas B, Celik P, Dell’Accio F, Yona S, Gilroy D, Voisin MB, Wood JN, Sikandar S. Neutrophils infiltrate sensory ganglia and mediate chronic widespread pain in fibromyalgia. Proc Natl Acad Sci U S A. 2023 Apr 25;120(17):e2211631120. doi: 10.1073/pnas.2211631120. Epub 2023 Apr 18. PMID: 37071676. https://www.pnas.org/doi/10.1073/pnas.2211631120 (Full text)

Efficacy of Low-Dose Naltrexone and Predictors of Treatment Success or Discontinuation in Fibromyalgia and Other Chronic Pain Conditions: A Fourteen-Year, Enterprise-Wide Retrospective Analysis

Abstract:

Current pharmacologic treatments may provide limited analgesia in fibromyalgia and other chronic pain disorders. Low-dose naltrexone (LDN) has emerged as a potential analgesic option that has been minimally explored.

This study aims to describe current real-world prescribing practices of LDN, to investigate if patients have a perceived benefit of LDN in treating pain symptoms and to identify predictors associated with a perceived benefit or discontinuation of LDN.

We evaluated all outpatient prescriptions for LDN prescribed for any pain indication in the Mayo Clinic Enterprise from 1 January 2009 to 10 September 2022. A total of 115 patients were included in the final analysis.

The patients were 86% female, had a mean age of 48 ± 16 years, and 61% of prescriptions were for fibromyalgia-related pain. The final daily dose of oral LDN ranged from 0.8 to 9.0 mg, while the most common dose was 4.5 mg once daily.

Of patients who reported follow-up data, 65% reported benefit in their pain symptoms while taking LDN. Adverse effects were reported in 11 (11%) patients and 36% discontinued taking LDN by the most recent follow-up.

Concomitant analgesic medications were used by 60% of patients and were not associated with perceived benefit nor discontinuation of LDN, including concomitant opioids.

LDN is a relatively safe pharmacologic option that may benefit patients with chronic pain conditions and warrants further investigation in a prospective, controlled, and well-powered randomized clinical trial.

Source: Driver CN, D’Souza RS. Efficacy of Low-Dose Naltrexone and Predictors of Treatment Success or Discontinuation in Fibromyalgia and Other Chronic Pain Conditions: A Fourteen-Year, Enterprise-Wide Retrospective Analysis. Biomedicines. 2023; 11(4):1087. https://doi.org/10.3390/biomedicines11041087 https://www.mdpi.com/2227-9059/11/4/1087 (Full text)

Synbiotic Supplementation Improves Quality of Life and Inmunoneuroendocrine Response in Patients with Fibromyalgia: Influence of Codiagnosis with Chronic Fatigue Syndrome

Abstract:

Fibromyalgia (FM) and chronic fatigue syndrome (CFS) are two medical conditions in which pain, fatigue, immune/inflammatory dysregulation, as well as various mental health disorders predominate in the diagnosis, without evidence of a clear consensus on the treatment of FM and CFS.
The main aim of this research was to analyse the possible effects of a synbiotic (Synbiotic, Gasteel Plus® (Heel España S.A.U.), through the study of pro-inflammatory/anti-inflammatory cytokines (IL-8/IL-10) and neuroendocrine biomarkers (cortisol and DHEA), in order to evaluate the interaction between inflammatory and stress responses mediated by the cytokine-HPA (hypothalamic-pituitary-adrenal) axis, as well as mental and physical health using body composition analysis, accelerometry and previously validated questionnaires.
The participants were women diagnosed with FM with or without a diagnostic of CFS. Each participant was evaluated at baseline and after the intervention, which lasted one month. Synbiotic intervention decreased levels of perceived stress, anxiety and depression, as well as improved quality of life during daily activities. In addition, the synbiotic generated an activation of HPA axis (physiological cortisol release) that can compensate the increased inflammatory status (elevated IL-8) observed at baseline in FM patients. There were no detrimental changes in body composition or sleep parameters, as well as in the most of the activity/sedentarism-related parameters studied by accelerometry.
It is concluded that synbiotic nutritional supplements can improve the dysregulated immunoneuroendocrine interaction involving inflammatory and stress responses in women diagnosed with FM, particularly in those without a previous CFS diagnostic; as well as their perceived of levels stress, anxiety, depression and quality of life.
Source: Hinchado MD, Quero-Calero CD, Otero E, Gálvez I, Ortega E. Synbiotic Supplementation Improves Quality of Life and Inmunoneuroendocrine Response in Patients with Fibromyalgia: Influence of Codiagnosis with Chronic Fatigue Syndrome. Nutrients. 2023; 15(7):1591. https://doi.org/10.3390/nu15071591 https://www.mdpi.com/2072-6643/15/7/1591 (Full text)

Heart Rate Variability and Salivary Biomarkers Differences between Fibromyalgia and Healthy Participants after an Exercise Fatigue Protocol: An Experimental Study

Abstract:

Previous studies showed that people with Fibromyalgia (FM) suffer from dysautonomia. Dysautonomia consists of persistent autonomic nervous system hyperactivity at rest and hyporeactivity during stressful situations. There is evidence that parameters reflecting the complex interplay between the autonomic nervous system and the cardiovascular system during exercise can provide significant prognostic information. Therefore, this study aimed to investigate the differences between people with FM and healthy controls on heart rate variability (HRV) and salivary parameters (such as flow, protein concentration, enzymatic activities of amylase, catalase and glutathione peroxidase) in two moments: (1) at baseline, and (2) after an exercise fatigue protocol.

A total of 37 participants, twenty-one were people with fibromyalgia and sixteen were healthy controls, participated in this cross-sectional study. HRV and salivary samples were collected before and after an exercise fatigue protocol. The fatigue protocol consisted of 20 repetitions of knee extensions and flexions of the dominant leg at 180 °·s-1 (degrees per second).

Significant differences were found in the HRV (stress index, LF and HF variables) and salivary biomarkers (with a higher concentration of salivary amylase in people with FM compared to healthy controls). Exercise acute effects on HRV showed that people with FM did not significantly react to exercise. However, significant differences between baseline and post-exercise on HRV significantly induce alteration on the HRV of healthy controls. Catalase significantly increased after exercise in healthy controls whereas salivary flow significantly increased in women with FM after an exercise fatigue protocol.

Our study suggests that a higher α-amylase activity and an impaired HRV can be used as possible biomarkers of fibromyalgia, associated with a reduction in salivary flow without changes in HRV and catalase activity after a fatigue exercise protocol. More studies should be carried out in the future to evaluate this hypothesis, in order to find diagnostic biomarkers in fibromyalgia.

Source: Costa AR, Freire A, Parraca JA, Silva V, Tomas-Carus P, Villafaina S. Heart Rate Variability and Salivary Biomarkers Differences between Fibromyalgia and Healthy Participants after an Exercise Fatigue Protocol: An Experimental Study. Diagnostics (Basel). 2022 Sep 14;12(9):2220. doi: 10.3390/diagnostics12092220. PMID: 36140620; PMCID: PMC9497903. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9497903/ (Full text)