Towards a Better Understanding of the Complexities of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Long COVID.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex condition arising in susceptible people, predominantly following viral infection, but also other stressful events. The susceptibility factors discussed here are both genetic and environmental although not well understood. While the dysfunctional physiology in ME/CFS is becoming clearer, understanding has been hampered by different combinations of symptoms in each affected person. A common core set of mainly neurological symptoms forms the modern clinical case definition, in the absence of an accessible molecular diagnostic test. This landscape has prompted interest in whether ME/CFS patients can be classified into a particular phenotype/subtype that might assist better management of their illness and suggest preferred therapeutic options. Currently, the same promising drugs, nutraceuticals, or behavioral therapies available can be beneficial, have no effect, or be detrimental to each individual patient. We have shown that individuals with the same disease profile exhibit unique molecular changes and physiological responses to stress, exercise and even vaccination. Key features of ME/CFS discussed here are the possible mechanisms determining the shift of an immune/inflammatory response from transient to chronic in ME/CFS, and how the brain and CNS manifests the neurological symptoms, likely with activation of its specific immune system and resulting neuroinflammation. The many cases of the post viral ME/CFS-like condition, Long COVID, following SARS-CoV-2 infection, and the intense research interest and investment in understanding this condition, provide exciting opportunities for the development of new therapeutics that will benefit ME/CFS patients.

Cardiovascular and haematological pathology in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): A role for viruses.

ME/CFS is a debilitating chronic condition that often develops after viral or bacterial infection. Insight from the study of Long COVID/Post Acute Sequelae of COVID-19 (PASC), the post-viral syndrome associated with SARS-CoV-2 infection, might prove to be useful for understanding pathophysiological mechanisms of ME/CFS. Disease presentation is similar between the two conditions, and a subset of Long COVID patients meet the diagnostic criteria for ME/CFS. Since Long COVID is characterized by significant vascular pathology - including endothelial dysfunction, coagulopathy, and vascular dysregulation - the question of whether or not the same biological abnormalities are of significance in ME/CFS arises. Cardiac abnormalities have for a while now been documented in ME/CFS cohorts, with recent studies demonstrating major deficits in cerebral blood flow, and hence vascular dysregulation. A growing body of research is demonstrating that ME/CFS is accompanied by platelet hyperactivation, anomalous clotting, a procoagulant phenotype, and endothelial dysfunction. Endothelial damage and dysregulated clotting can impair substance exchange between blood and tissues, and result in hypoperfusion, which may contribute to the manifestation of certain ME/CFS symptoms. Here we review the ME/CFS literature to summarize cardiovascular and haematological findings documented in patients with the condition, and, in this context, briefly discuss the potential role of previously-implicated pathogens. Overall, cardiac and haematological abnormalities are present within ME/CFS cohorts. While atherosclerotic heart disease is not significantly associated with ME/CFS, suboptimal cardiovascular function defined by reduced cardiac output, impaired cerebral blood flow, and vascular dysregulation are, and these abnormalities do not appear to be influenced by deconditioning. Rather, these cardiac abnormalities may result from dysfunction in the (autonomic) nervous system. Plenty of recently published studies are demonstrating significant platelet hyperactivity and endothelial dysfunction in ME/CFS, as well as anomalous clotting processes. It is of particular importance to determine to what extent these cardiovascular and haematological abnormalities contribute to symptom severity, and if these two systems can be targeted for therapeutic purposes. Viral reservoirs of herpesviruses exist in ME/CFS, and most likely contribute to cardiovascular and haematological dysfunction directly or indirectly. This review highlights the potential of studying cardiac functioning, the vasculature, and coagulation system in ME/CFS.

Real world research on transcranial magnetic stimulation treatment strategies for neuropsychiatric symptoms with long-COVID in Japan.

The number of patients suffering from long-COVID is currently increasing rapidly, even after the acute symptoms of COVID-19 have improved. The objective of this study was to investigate the effects of a pilot transcranial magnetic stimulation (TMS) treatment on neuropsychiatric symptoms caused by long-COVID. In this study, we examined the efficacy of the TMS treatment protocol, which has been established to be effective in refractory depression, by applying it to patients who sought TMS treatment for neuropsychiatric symptoms caused by long-COVID at TMS clinics in Tokyo, Japan in the context of the real world TMS registry study in Japan. Of the 23 patients (13 females) with long-COVID included in this case series, the main neuropsychiatric symptoms were chronic fatigue (n = 12) and cognitive dysfunction (n = 11), but most patients also showed mild depressive symptoms. The mean score on the Montgomery-Åsberg Depression Rating Scale before TMS treatment was 21.2, which improved to 9.8 after treatment. Similarly, the score on the Performance Status, which assesses the degree of fatigue, improved from 5.4 to 4.2, and the score on the Perceived Deficits Questionnaire-Depression 5-item, which reflects cognitive function, improved from 10.0 to 6.3. Although a few patients complained of pain at the stimulation site during the TMS as a side effect, there were no serious adverse events. Despite the limitations of this open-label pilot study, the TMS protocol implemented in this study may have beneficial effects on neuropsychiatric symptoms caused by long-COVID, including depressive symptoms, chronic fatigue, and cognitive impairment. These preliminary findings warrant further validation in randomized controlled trials.

No Causal Effects Detected in COVID-19 and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Two Sample Mendelian Randomization Study.

New clinical observational studies suggest that Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a sequela of COVID-19 infection, but whether there is an exact causal relationship between COVID-19 and ME/CFS remains to be verified. To investigate whether infection with COVID-19 actually causes ME/CFS, this paper obtained pooled data from the Genome Wide Association Study (GWAS) and analyzed the relationship between COVID susceptibility, hospitalization and severity of COVID and ME/CFS, respectively, using two-sample Mendelian randomization (TSMR). TSMR analysis was performed by inverse variance weighting (IVW), weighted median method, MR-Egger regression and weighted mode and simple mode methods, respectively, and then the causal relationship between COVID-19 and ME/CFS was further evaluated by odds ratio (OR). Eventually, we found that COVID-19 severity, hospitalization and susceptibility were all not significantly correlated with ME/CFS (OR:1.000,1.000,1.000; 95% CI:0.999-1.000, 0.999-1.001, 0.998-1.002; p = 0.333, 0.862, 0.998, respectively). We found the results to be reliable after sensitivity analysis. These results suggested that SARS-CoV-2 infection may not significantly contribute to the elevated risk of developing CFS, and therefore ME/CFS may not be a sequela of COVID-19, but may simply present with symptoms similar to those of CFS after COVID-19 infection, and thus should be judged and differentiated by physicians when diagnosing and treating the disease in clinical practice.

The Fatigue-Related Symptoms Post-Acute SARS-CoV-2: A Preliminary Comparative Study.

A sizeable sub-group of individuals continue to experience persistent debilitating symptoms post-acute SARS-CoV-2. Although these can vary from person to person, fatigue appears to be the most common symptom. Post-viral fatigue has been documented in conditions such as influenza, infectious mononucleosis and more recently chronic fatigue syndrome (CFS). The current study uses measures that successfully describe the fatigue-related symptoms associated with CFS to investigate the fatigue experienced post-acute SARS-CoV-2. Twenty-six volunteers were recruited from Long COVID support groups active on social media. Data were collected anonymously using an online survey platform. These data were compared to pre-pandemic data from non-fatigued and CFS groups. The post-acute SARS-CoV-2 volunteers reported significantly higher levels of fatigue and cognitive difficulties than the non-fatigued controls. They also report more individual symptoms (such as lack of concentration) and problems with sleep quality. There was a similarity between the post-acute SARS-CoV-2 volunteers and the CFS group in terms of levels of depression, perceived stress, emotional distress and cognitive difficulties. Although this was a small-scale study, it demonstrates the range of symptoms experienced post-acute SARS-CoV-2. In addition, the similarities between this group and CFS suggests the need for further research into the mechanisms at play here, the need to identify those at risk of long-term symptoms and the development of possible interventions.

Post-viral fatigue in COVID-19: A review of symptom assessment methods, mental, cognitive, and physical impairment.

Coronavirus 2 is responsible for Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2), and the main sequela is persistent fatigue. Post-viral fatigue is common and affects patients with mild, asymptomatic coronavirus disease-2019 (COVID-19). However, the exact mechanisms involved in developing post-COVID-19 fatigue remain unclear. Furthermore, physical and cognitive impairments in these individuals have been widely described. Therefore, this review aims to summarize and propose tools from a multifaceted perspective to assess COVID-19 infection. Herein, we point out the instruments that can be used to assess fatigue in long-term COVID-19: fatigue in a subjective manner or fatigability in an objective manner. For physical and mental fatigue, structured questionnaires were used to assess perceived symptoms, and physical and cognitive performance assessment tests were used to measure fatigability using reduced performance.

Protracted stress-induced hypocortisolemia may account for the clinical and immune manifestations of Long COVID.

About one out of eight people to convalesce from COVID-19 suffer from the so called Long COVID, a syndrome of non-specific symptoms with unclear pathogenesis. In a recent study published in Cell Long COVID participants reporting respiratory symptoms had low cortisol levels. In an as yet unpublished analysis from Yale University low plasma cortisol levels discriminated Long COVID from asymptomatic convalescent or healthy non-infected controls. Although various immune perturbations were present in Long COVID, low levels of cortisol were prominent and strikingly, depression and anxiety were increased. It has become clear that Long COVID features may be similar to those described in myalgic encephalomyelitis/chronic fatigue syndrome, post-SARS sickness syndrome, and various chronic stress syndromes which have been linked to hypocortisolemia. Notably, lack of response of the hypothalamic-pituitary-adrenal axis to hypocortisolemia shows a suppressed axis in Long COVID. We suggest that the inability of hypothalamic-pituitary-adrenal axis to recover after the acute illness, perhaps due to protracted stress in predisposed individuals, may represent the pathogenetic basis of the Long COVID-associated clinical and immunological manifestations.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: First Described Complication after Gam-COVID-Vac Vaccine.

BACKGROUND: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a severe, debilitating chronic disease characterized by marked tiredness and fatigue, cognitive dysfunction, sleep disturbances, pain, and autonomic, immunological, and metabolic dysfunctions, in which all symptoms are usually exacerbated by physical and/or psychological stress. SUBJECTS AND METHODS: We report a case of ME/CFS with severe myalgia and severe locomotor disorders in a 25-year-old female after Gam-COVID-Vac vaccine (Sputnik V) ten days before the manifestation of the symptoms. RESULTS: This is the first report of such a complication from the Gam-COVID-Vac vaccine.

Chronic Fatigue Associated with Post-COVID Syndrome versus Transient Fatigue Caused by High-Intensity Exercise: Are They Comparable in Terms of Vascular Effects?

Purpose: The pathophysiology of chronic fatigue associated with post-COVID syndrome is not well recognized. It is assumed that this condition is partly due to vascular dysfunction developed during an acute phase of infection. There is great demand for a diagnostic tool that is able to clinically assess post-COVID syndrome and monitor the rehabilitation process. Patients and Methods: The Flow Mediated Skin Fluorescence (FMSF) technique appears uniquely suitable for the analysis of basal microcirculatory oscillations and reactive hyperemia induced by transient ischemia. The FMSF was used to measure vascular circulation in 45 patients with post-COVID syndrome. The results were compared with those for a group of 26 amateur runners before and after high-intensity exercise as well as for a control group of 32 healthy age-matched individuals. Results: Based on the observed changes in the NOI (Normoxia Oscillatory Index) and RHR (Reactive Hyperemia Response) parameters measured with the FMSF technique, it was found that chronic fatigue associated with post-COVID syndrome is comparable with transient fatigue caused by high-intensity exercise in terms of vascular effects, which are associated with vascular stress in the macrocirculation and microcirculation. Acute and chronic fatigue symptomatology shared similarly altered changes in the NOI and RHR parameters and both can be linked to calcium homeostasis modification. Conclusion: The NOI and RHR parameters measured with the FMSF technique can be used for non-invasive clinical assessment of post-COVID syndrome as well as for monitoring the rehabilitation process.

Unexplained post-acute infection syndromes.

SARS-CoV-2 is not unique in its ability to cause post-acute sequelae; certain acute infections have long been associated with an unexplained chronic disability in a minority of patients. These post-acute infection syndromes (PAISs) represent a substantial healthcare burden, but there is a lack of understanding of the underlying mechanisms, representing a significant blind spot in the field of medicine. The relatively similar symptom profiles of individual PAISs, irrespective of the infectious agent, as well as the overlap of clinical features with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), suggest the potential involvement of a common etiopathogenesis. In this Review, we summarize what is known about unexplained PAISs, provide context for post-acute sequelae of SARS-CoV-2 infection (PASC), and delineate the need for basic biomedical research into the underlying mechanisms behind this group of enigmatic chronic illnesses.

Dyspnea in Post-COVID Syndrome following Mild Acute COVID-19 Infections: Potential Causes and Consequences for a Therapeutic Approach.

Dyspnea, shortness of breath, and chest pain are frequent symptoms of post-COVID syndrome (PCS). These symptoms are unrelated to organ damage in most patients after mild acute COVID infection. Hyperventilation has been identified as a cause of exercise-induced dyspnea in PCS. Since there is a broad overlap in symptomatology with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), causes for dyspnea and potential consequences can be deduced by a stringent application of assumptions made for ME/CFS in our recent review papers. One of the first stimuli of respiration in exercise is caused by metabolic feedback via skeletal muscle afferents. Hyperventilation in PCS, which occurs early on during exercise, can arise from a combined disturbance of a poor skeletal muscle energetic situation and autonomic dysfunction (overshooting respiratory response), both found in ME/CFS. The exaggerated respiratory response aggravating dyspnea does not only limit the ability to exercise but further impairs the muscular energetic situation: one of the buffering mechanisms to respiratory alkalosis is a proton shift from intracellular to extracellular space via the sodium-proton-exchanger subtype 1 (NHE1), thereby loading cells with sodium. This adds to two other sodium loading mechanisms already operative, namely glycolytic metabolism (intracellular acidosis) and impaired Na+/K+ATPase activity. High intracellular sodium has unfavorable effects on mitochondrial calcium and metabolism via sodium-calcium-exchangers (NCX). Mitochondrial calcium overload by high intracellular sodium reversing the transport mode of NCX to import calcium is a key driver for fatigue and chronification. Prevention of hyperventilation has a therapeutic potential by keeping intracellular sodium below the threshold where calcium overload occurs.

[Mechanisms underlying chronic fatigue, a symptom too often overlooked II- From deregulated immunity to neuroinflammation and its consequences]. / Mécanismes sous-jacents à la fatigue chronique, un symptôme trop souvent négligé - II. De l'immunité dérégulée à la neuroinflammation et ses conséquences.

Hypothalamus stimulation by inflammatory and / or stress signals can trigger activation of the HPA (hypothalamic-pituitary-adrenal) axis, which includes the hypothalamus, pituitary and adrenal gland. Acute activation of the HPA axis is fundamental for the fight or flight response. It allows a maximal energy mobilization available for an effort, whilst erasing fatigue. On the contrary, the chronic activation of this axis decreases muscle efficiency and leads to chronic fatigue. In this second part of our review will be discussed several strategic points that need to be considered for attempting to understand and treat together inflammation and chronic fatigue.

TITLE: Mécanismes sous-jacents à la fatigue chronique, un symptôme trop souvent négligé - II. De l'immunité dérégulée à la neuroinflammation et ses conséquences. ABSTRACT: L'activation de l'hypothalamus par des signaux inflammatoires et/ou de stress peut déclencher celle de l'axe HPA (hypothalamic-pituitary-adrenal axis), qui intègre l'hypothalamus, l'hypophyse et la glande surrénale. L'activation aiguë de l'axe HPA est fondamentale pour la réponse fight or flight (« combats ou fuis ¼). Elle permet de mobiliser un maximum d'énergie pour un effort, tout en effaçant la fatigue. En revanche, son activation chronique diminue l'efficacité musculaire et entraîne une fatigue chronique. On discutera dans cette partie de plusieurs points stratégiques à considérer pour tenter de comprendre et de traiter ensemble inflammation et fatigue chroniques.

Proposed subtypes of post-COVID-19 syndrome (or long-COVID) and their respective potential therapies.

The effects of coronavirus disease 2019 (COVID-19), a highly transmissible infectious respiratory disease that has initiated an ongoing pandemic since early 2020, do not always end in the acute phase. Depending on the study referred, about 10%-30% (or more) of COVID-19 survivors may develop long-COVID or post-COVID-19 syndrome (PCS), characterised by persistent symptoms (most commonly fatigue, dyspnoea, and cognitive impairments) lasting for 3 months or more after acute COVID-19. While the pathophysiological mechanisms of PCS have been extensively described elsewhere, the subtypes of PCS have not. Owing to its highly multifaceted nature, this review proposes and characterises six subtypes of PCS based on the existing literature. The subtypes are non-severe COVID-19 multi-organ sequelae (NSC-MOS), pulmonary fibrosis sequelae (PFS), myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS), postural orthostatic tachycardia syndrome (POTS), post-intensive care syndrome (PICS) and medical or clinical sequelae (MCS). Original studies supporting each of these subtypes are documented in this review, as well as their respective symptoms and potential interventions. Ultimately, the subtyping proposed herein aims to provide better clarity on the current understanding of PCS.

Fatigue in post-acute sequelae of SARS-CoV2 (PASC) treated with oxygen-ozone autohemotherapy - preliminary results on 100 patients.

OBJECTIVE: Post-acute sequelae of SARS-CoV2 infection (PASC) are a novel terminology used to describe post-COVID persistent symptoms, mimicking somehow the previously described chronic fatigue syndrome (CFS). In this manuscript, we evaluated a therapeutical approach to address PASC-derived fatigue in a cohort of past-COVID-19 positive patients. PATIENTS AND METHODS: A number of 100 patients, previously diagnosed as COVID-19 positive subjects and meeting our eligibility criteria, was diagnosed having PASC-related fatigue. They were recruited in the study and treated with oxygen-ozone autohemotherapy (O2-O3-AHT), according to the SIOOT protocol. Patients' response to O2-O3-AHT and changes in fatigue were measured with the 7-scoring Fatigue Severity Scale (FSS), according to previously published protocols. RESULTS: Statistics assessed that the effects of O2-O3-AHT on fatigue reduced PASC symptoms by 67%, as a mean, in all the investigated cohort of patients (H = 148.4786 p < 0.0001) (Figure 1). Patients following O2-O3-AHT therapy, quite completely recovered for PASC-associated fatigue, a quote amounting to about two fifths (around 40%) of the whole cohort undergoing ozone treatment and despite most of patients were female subjects, the effect was not influenced by sex distribution (H = 0.7353, p = 0.39117). CONCLUSIONS: Ozone therapy is able to recover normal functionality and to relief pain and discomfort in the form of PASC-associated fatigue in at least 67% of patients suffering from post-COVID sequelae, aside from sex and age distribution.

[Long COVID: Is it really myalgic encephalomyelitis? Bibliographic review and considerations]. / COVID persistente: ¿es en realidad una encefalomielitis miálgica? Revisión bibliográfica y consideraciones.

Clinical sequelae of a disease as widespread as COVID-19 can be of great importance for primary care due to their prevalence and the morbidity they entail. The definition of long COVID and the establishment of its temporality are various, but some authors consider possible that this syndrome is actually myalgic encephalomyelitis. Similarities are observed when comparing the International Consensus Criteria for the diagnosis of myalgic encephalomyelitis with the symptoms described for long COVID. Blood tests, pulse oximetry, chest radiography, and thoracic ultrasound are recommended in patients with persistent symptoms after acute infection. Management in both conditions consists of treating the main symptoms. The possibility that COVID-19 can lead to a chronic condition such as myalgic encephalomyelitis makes long-term follow-up of patients who have suffered from this infection essential.

Insights from myalgic encephalomyelitis/chronic fatigue syndrome may help unravel the pathogenesis of postacute COVID-19 syndrome.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can cause chronic and acute disease. Postacute sequelae of SARS-CoV-2 infection (PASC) include injury to the lungs, heart, kidneys, and brain that may produce a variety of symptoms. PASC also includes a post-coronavirus disease 2019 (COVID-19) syndrome ('long COVID') with features that can follow other acute infectious diseases and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Here we summarize what is known about the pathogenesis of ME/CFS and of 'acute' COVID-19, and we speculate that the pathogenesis of post-COVID-19 syndrome in some people may be similar to that of ME/CFS. We propose molecular mechanisms that might explain the fatigue and related symptoms in both illnesses, and we suggest a research agenda for both ME/CFS and post-COVID-19 syndrome.

Post COVID fatigue: Can we really ignore it?

Long-COVID, also referred to as post-acute COVID-19, chronic COVID-19, post-COVID syndrome, or post-acute sequelae of SARS-CoV-2 infection (PASC), generally refers to symptoms that develop during or after acute COVID-19 illness, continue for ≥12 weeks, and are not explained by an alternative diagnosis. It is not yet known whether "long-COVID" represents a new syndrome unique to COVID-19 or overlaps with recovery from similar illnesses. It's difficult for physicians to predict when symptoms will improve as it varies differently in different people. Patient's recovery depends on various factors including age, associated comorbidities, severity of COVID-19 infection. Some symptoms, like fatigue, might continue even while others improve or go away. This review addresses the pathogenesis, presentation of post covid fatigue, its severity and its management.