Tag: review

Pathological Mechanisms Underlying Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

The underlying molecular basis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is not well understood. Characterized by chronic, unexplained fatigue, a disabling payback following exertion (“post-exertional malaise”) and variably presenting, multi-system symptoms, ME/CFS is a complex disease which demands concerted biomedical investigation from disparate fields of expertise.

ME/CFS research and patient treatment have been challenged by the lack of diagnostic biomarkers and finding these is a prominent direction of current work. Despite these challenges, modern research demonstrates a tangible biomedical basis for the disorder across many body systems. This evidence is largely comprised of disturbances to immunological and inflammatory pathways, autonomic and neurologic systems, abnormalities in muscle and mitochondrial function, shifts in metabolism, and gut physiology or gut microbiome disturbances. It is possible that these threads are together entangled as parts of an underlying molecular pathology reflecting a far-reaching homeostatic shift affecting each of these systems.

Due to the variability of non-overlapping symptom presentation or precipitating events such as infection or other bodily stresses, the initiation of body-wide pathological cascades with similar outcomes stemming from different causes may be implicated in the condition. Patient stratification to account for this heterogeneity is therefore one important consideration during exploration of potential diagnostic developments.

Source: Missailidis, D.; Annesley, S.; Fisher, P. Pathological Mechanisms Underlying Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Preprints 2019, 2019070196 (doi: 10.20944/preprints201907.0196.v1). https://www.preprints.org/manuscript/201907.0196/v1

Myalgic encephalomyelitis or chronic fatigue syndrome

Abstract:

In this review, we discuss the myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), which is characterised by extreme mental and physical fatigue with associated symptoms of pain, disturbed sleep, cognitive and autonomic dysfunction, as well as post-exertional malaise. This condition is often preceded by an infection, severe physiological and/or psychological strain. Over the last decades, research has demonstrated mitochondrial, neuroendocrine, immunological, and metabolic perturbations in patients with ME/CFS, giving hope for the development of new biomarkers and new treatment modalities.

Source: Brinth L, Nielsen H, Varming K, Boonen SE, Ebsen ACG, Fernández-Guerra P, Schou AS, Mehlsen J, Gregersen N, Brandslund I, Olsen RKJ. Myalgic encephalomyelitis or chronic fatigue syndrome. Ugeskr Laeger. 2019 Jun 10;181(24). pii: V08180570. [Article in Danish] https://www.ncbi.nlm.nih.gov/pubmed/31267953

Advances in Understanding the Pathophysiology of Chronic Fatigue Syndrome

Introduction:

The illness now called myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) was first described in the mid-1980s. At that time, nothing was known about its underlying biology. Indeed, because many standard laboratory test results were normal, some clinicians explained to patients that “there is nothing wrong.” There was, of course, an alternative explanation: the standard laboratory tests might not have been the right tests to identify the underlying abnormalities.

Over the past 35 years, thousands of studies from laboratories in many countries have documented underlying biological abnormalities involving many organ systems in patients with ME/CFS, compared with healthy controls: in short, there is something wrong. Moreover, most of the abnormalities are not detected by standard laboratory tests. In 2015, the Institute of Medicine of the National Academy of Sciences concluded that ME/CFS “is a serious, chronic, complex systemic disease that often can profoundly affect the lives of patients,” affects up to an estimated 2.5 million people in the United States, and generates direct and indirect expenses of approximately $17 billion to $24 billion annually.

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Source: Anthony L. Komaroff, MD. Advances in Understanding the Pathophysiology of Chronic Fatigue Syndrome. JAMA. Published online July 5, 2019. doi:10.1001/jama.2019.8312 https://jamanetwork.com/journals/jama/fullarticle/2737854 (Full article)

The clinical value of cytokines in chronic fatigue syndrome

Abstract:

Chronic fatigue syndrome (CFS) is a heterogeneous disorder with uncertain pathogenesis. Without effective therapy, CFS is characterized by disabling fatigue, depression, memory loss, and somatic discomfort. This comprehensive and impartial review aimed to assess the available evidence and examined the potential clinical value of using cytokines for the monitoring of CFS and as targets for the treatment of CFS.

Inflammatory reactions and immune modulation are considered to contribute to the pathophysiology of CFS, and it is well documented that cytokines present in both blood and cerebrospinal fluid (CSF) are closely associated with the progression and severity of CFS. However, pathophysiological and methodological limitations prevent using circulating cytokines as independent diagnostic indices. Moreover, there is no evidence to support the use of CSF cytokines as independent diagnostic indices.

Nevertheless, a comprehensive evaluation of changes in circulating and CSF cytokines may improve clinical understanding of the pathophysiology of patients with CFS, aiding in the establishment of an appropriate diagnosis. Importantly, the available evidence does not support the value of cytokines as therapeutic targets. We believe that an improved understanding of cytokine-related mechanisms will be helpful to explore new cytokine-related therapeutic targets.

Source: Yang T, Yang Y, Wang D, Li C, Qu Y, Guo J, Shi T, Bo W, Sun Z, Asakawa T. The clinical value of cytokines in chronic fatigue syndrome. J Transl Med. 2019 Jun 28;17(1):213. doi: 10.1186/s12967-019-1948-6 https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-019-1948-6 (Full article)

Understanding Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and the Emerging Osteopathic Approach: A Narrative Review

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating syndrome of unknown origin, characterized by profound postexertional malaise and fatigue, unrefreshing sleep, cognitive impairments, immune dysfunction, pain, autonomic dysfunction, and neuroendocrine symptoms. Although ME/CFS is well documented within the medical literature, it remains difficult to diagnosis and manage.

Some of the current challenges include an absence of diagnostic markers, differing diagnostic criteria, and an overall lack of awareness within the medical community. As a result, patients are often frustrated by the difficulties in acquiring a diagnosis and from the overall lack of available treatments. In an effort to increase awareness, this review discusses disease pathophysiology, clinical presentation, and treatment options, while also highlighting the benefits of an osteopathic approach.

J Am Osteopath Assoc. 2019 Jul 1;119(7):446-455. doi: 10.7556/jaoa.2019.081.

Source: Larrimore C, Ramnot A, Jaghab A, Sarduy S, Guerrero G, Troccoli P, Hilton K, Bested A. Understanding Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and the Emerging Osteopathic Approach: A Narrative Review. J Am Osteopath Assoc. 2019 Jul 1;119(7):446-455. doi: 10.7556/jaoa.2019.081. https://www.ncbi.nlm.nih.gov/pubmed/31233110

Myalgic Encephalomyelitis, Chronic Fatigue Syndrome, and Chronic Fatigue: Three Distinct Entities Requiring Complete Different Approaches

Abstract:

PURPOSE OF REVIEW: A recent review implicates that myalgic encephalomyelitis (ME), chronic fatigue syndrome (CFS), and chronic fatigue are part of the “fatigue spectrum” and recommends “longitudinal studies integrating biopsychosocial approaches to inform early management and targeted rehabilitation strategies.”

RECENT FINDINGS: ME is a neuromuscular disease distinguished by muscle fatigability (prolonged muscle weakness after minor exertion) and specific signs of neurological dysfunction. ME is not equivalent to CFS, as proposed by the authors. CFS is defined as unexplained chronic fatigue accompanied by at least four out of a list of eight specific symptoms. CFS is a distinct clinical entity and not merely a severe variant of CF, as suggested. Proof that CF, CFS, and ME are part of a “fatigue continuum” and that CF can convert to CFS at a later stage is lacking. Biopsychosocial approaches for early management and rehabilitation of CF, as promoted by the authors, are at odds with the current understandings of ME, CFS, and CF. The (bio)psychosocial explanatory models for ME and CFS have proven to be invalid, and the associated interventions, cognitive behavioral therapy and graded exercise therapy, have shown to be ineffective and even potentially harmful. ME, CFS, and CF are three very distinct clinical entities. Interventions justified by (bio)psychosocial models appear to be unsuccessful and potentially noxious. To develop effective treatments, it is crucial to make a clear distinction between ME, CFS, and CF and to leave the (bio)psychosocial explanations and therapies behind us.

Source: Twisk FNM. Myalgic Encephalomyelitis, Chronic Fatigue Syndrome, and Chronic Fatigue: Three Distinct Entities Requiring Complete Different Approaches. Curr Rheumatol Rep. 2019 May 9;21(6):27. doi: 10.1007/s11926-019-0823-z. https://www.ncbi.nlm.nih.gov/pubmed/31073713

Assessment of the scientific rigour of randomized controlled trials on the effectiveness of cognitive behavioural therapy and graded exercise therapy for patients with myalgic encephalomyelitis/chronic fatigue syndrome: A systematic review

Abstract:

Cognitive behavioural therapy and graded exercise therapy have been promoted as effective treatments for patients with myalgic encephalomyelitis/chronic fatigue syndrome. However, criticism on the scientific rigour of these studies has been raised. This review assessed the methodological quality of studies on the effectiveness of cognitive behavioural therapy and graded exercise therapy. The methodological quality of the 18 included studies was found to be relatively low, as bias was prominently found, affecting the main outcome measures of the studies (fatigue, physical functioning and functional impairment/status). Future research should focus on including more objective outcome measures in a well-defined patient population.

Source: Ahmed SA, Mewes JC, Vrijhoef H. Assessment of the scientific rigour of randomized controlled trials on the effectiveness of cognitive behavioural therapy and graded exercise therapy for patients with myalgic encephalomyelitis/chronic fatigue syndrome: A systematic review. J Health Psychol. 2019 May 10:1359105319847261. doi: 10.1177/1359105319847261. [Epub ahead of print] https://www.ncbi.nlm.nih.gov/pubmed/31072121

The ‘cognitive behavioural model’ of chronic fatigue syndrome: Critique of a flawed model

Abstract:

Chronic fatigue syndrome/myalgic encephalomyelitis is a debilitating illness that greatly impacts the lives of sufferers. A cognitive behavioural model attempts to explain illness onset and continuance with a hypothesis that the illness is perpetuated by patients’ irrational beliefs and avoidance behaviours. This theory underpins the promotion of cognitive behavioural therapy, a treatment that aims to change beliefs and behaviours. This article reports on a detailed review of the cognitive behavioural model. Our review finds that the model lacks high-quality evidential support, conflicts with accounts given by most patients and fails to account for accumulating biological evidence of pathological and physiological abnormalities found in patients. There is little scientific credibility in the claim that psycho-behavioural therapies are a primary treatment for this illness.

Source: Keith Geraghty, Leonard Jason, Madison Sunnquist, David Tuller, Charlotte Blease, Charles Adeniji. The ‘cognitive behavioural model’ of chronic fatigue syndrome: Critique of a flawed model. Health Psychology Open, Volume: 6 issue: 1,
Article first published online: April 23, 2019; Issue published: January 1, 2019. https://journals.sagepub.com/doi/10.1177/2055102919838907 (Full article)

Chronotropic Intolerance: An Overlooked Determinant of Symptoms and Activity Limitation in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome?

Abstract:

Post-exertional malaise (PEM) is the hallmark clinical feature of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). PEM involves a constellation of substantially disabling signs and symptoms that occur in response to physical, mental, emotional, and spiritual over-exertion. Because PEM occurs in response to over-exertion, physiological measurements obtained during standardized exertional paradigms hold promise to contribute greatly to our understanding of the cardiovascular, pulmonary, and metabolic states underlying PEM.

In turn, information from standardized exertional paradigms can inform patho-etiologic studies and analeptic management strategies in people with ME/CFS. Several studies have been published that describe physiologic responses to exercise in people with ME/CFS, using maximal cardiopulmonary testing (CPET) as a standardized physiologic stressor. In both non-disabled people and people with a wide range of health conditions, the relationship between exercise heart rate (HR) and exercise workload during maximal CPET are repeatable and demonstrate a positive linear relationship.

However, smaller or reduced increases in heart rate during CPET are consistently observed in ME/CFS. This blunted rise in heart rate is called chronotropic intolerance (CI). CI reflects an inability to appropriately increase cardiac output because of smaller than expected increases in heart rate. The purposes of this review are to (1) define CI and discuss its applications to clinical populations; (2) summarize existing data regarding heart rate responses to exercise obtained during maximal CPET in people with ME/CFS that have been published in the peer-reviewed literature through systematic review and meta-analysis; and (3) discuss how trends related to CI in ME/CFS observed in the literature should influence future patho-etiological research designs and clinical practice.

Source: Todd E. Davenport, Mary Lehnen, Staci R. Stevens, J. Mark VanNess, Jared Stevens and Christopher R. Snell. Chronotropic Intolerance: An Overlooked Determinant of Symptoms and Activity Limitation in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome? Front. Pediatr., 22 March 2019 | https://doi.org/10.3389/fped.2019.00082 https://www.frontiersin.org/articles/10.3389/fped.2019.00082/full (Full article)

The Invisible Burden of Chronic Fatigue in the Community: a Narrative Review

Abstract:

PURPOSE OF REVIEW: Unexplained fatigue is commonly reported in the general population, with varying severity. Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) sits at the extreme of the fatigue continuum, yet more individuals experience unexplained prolonged fatigue (1-6-month duration) or chronic fatigue (> 6 months) that, although debilitating, does not fulfil ME/CFS criteria. This review examines the empirical literature comparing symptoms for those with prolonged fatigue, chronic fatigue and ME/CFS.

RECENT FINDINGS: Substantial overlap of self-reported psychological, physical and functional impairments exists between chronic fatigue and ME/CFS. The conversion rate from prolonged or chronic fatigue to ME/CFS is not understood. Current research has failed to uncover factors accounting for differences in fatigue trajectories, nor incorporate comprehensive, longitudinal assessments extending beyond self-reported symptoms. Distinguishing factors between prolonged fatigue, chronic fatigue and ME/CFS remain poorly understood, highlighting a need for longitudinal studies integrating biopsychosocial approaches to inform early management and targeted rehabilitation strategies.

Source: Fatt SJ, Cvejic E2,, Lloyd AR, Vollmer-Conna U, Beilharz JE. The Invisible Burden of Chronic Fatigue in the Community: a Narrative Review. Curr Rheumatol Rep. 2019 Feb 11;21(2):5. doi: 10.1007/s11926-019-0804-2.