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

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.

Replacing Myalgic Encephalomyelitis and Chronic Fatigue Syndrome with Systemic Exercise Intolerance Disease Is Not the Way forward.

Myalgic encephalomyelitis (ME), described in the medical literature since 1938, is characterized by distinctive muscular symptoms, neurological symptoms, and signs of circulatory impairment. The only mandatory feature of chronic fatigue syndrome (CFS), introduced in 1988 and redefined in 1994, is chronic fatigue, which should be accompanied by at least four or more out of eight "additional" symptoms. The use of the abstract, polythetic criteria of CFS, which define a heterogeneous patient population, and self-report has hampered both scientific progress and accurate diagnosis. To resolve the "diagnostic impasse" the Institute of Medicine proposes that a new clinical entity, systemic exercise intolerance disease (SEID), should replace the clinical entities ME and CFS. However, adopting SEID and its defining symptoms, does not resolve methodological and diagnostic issues. Firstly, a new diagnostic entity cannot replace two distinct, partially overlapping, clinical entities such as ME and CFS. Secondly, due to the nature of the diagnostic criteria, the employment of self-report, and the lack of criteria to exclude patients with other conditions, the SEID criteria seem to select an even more heterogeneous patient population, causing additional diagnostic confusion. This article discusses methodological and diagnostic issues related to SEID and proposes a methodological solution for the current "diagnostic impasse".

A critical analysis of the proposal of the Institute of Medicine to replace myalgic encephalomyelitis and chronic fatigue syndrome by a new diagnostic entity called systemic exertion intolerance disease.

The Institute of Medicine (IOM) recently published their report in response to an assignment "to define diagnostic criteria for Myalgic Encephalomyelitis (ME)/chronic fatigue syndrome (CFS), to propose a process for reevaluation of these criteria in the future, and to consider whether a new name for this disease is warranted". The basic pre-assumption of the IOM committee for the development of evidence-based diagnostic criteria for ME/CFS was that ME and CFS denote conditions with similar symptoms, hence ME/CFS. The IOM committee recommends: (1) that ME/CFS will be renamed 'systemic exertion intolerance disease' (SEID); and that a new code should be assigned to SEID in the International Classification of Diseases (ICD), replacing the existing codes for ME (a neurological disease: G93.3) and CFS ('signs, symptoms, and abnormal clinical and laboratory findings, not elsewhere classified': R53.82); (2) that a diagnosis of SEID should be made if the new diagnostic criteria are met; (3) that the Department of Health and Human Services develops a toolkit appropriate for screening and diagnosing patients; and (4) that a multidisciplinary group re-examines the new diagnostic criteria when necessary. This editorial reviews the working procedure of the IOM and two of the outcomes: the recommendation to introduce a new clinical entity (SEID) and new diagnostic criteria. Based upon the contents of the report, and the arguments of the IOM, a search of PubMed and the archive of the Journal of Chronic Fatigue Syndrome using the search terms ME (and old synonyms) and CFS, and a search of PubMed related to the five core symptoms of SEID was conducted. Reviewing the working method and the recommendations, it is concluded that the new diagnostic criteria for SEID are based upon important methodological shortcomings and that the introduction of SEID to replace both ME and CFS has several profound negative consequences outweighing the advantages.

A definition of recovery in myalgic encephalomyelitis and chronic fatigue syndrome should be based upon objective measures.

INTRODUCTION: Adamowicz and colleagues recently proposed to use "a consistent definition of recovery that captures a broad-based return to health with assessments of both fatigue and function as well as the patients' perceptions of his/her recovery status" for patients with chronic fatigue syndrome (CFS). METHODS: A qualitative analysis of case definitions for Myalgic encephalomyelitis (ME) and CFS and methods to assess the symptoms and clinical status of ME and CFS patients objectively. RESULTS: The criteria of CFS define a heterogeneous disorder. ME, often used interchangeably with CFS, is principally defined by muscle weakness, cognitive impairment etc., but above all post-exertional "malaise": a long-lasting increase in symptoms, e.g. muscle pain and cognitive deficits, after a minor exertion. The principle symptom of CFS however is "chronic fatigue". Since post-exertional "malaise" is not obligatory for CFS, only part of the CFS patients meet the diagnostic criteria for ME, while not all ME patients qualify as CFS patients. There are several accepted methods to assess characteristic symptoms and the clinical status of ME and CFS patients using objective measures, e.g. (repeated) cardiopulmonary exercise tests. CONCLUSION: To resolve the debate about the clinical status, proposed effectiveness of therapies and recovery in ME and CFS, it is crucial to accurately diagnose patients using well-defined criteria for ME and CFS and an objective assessment of various typical symptoms, since subjective measures such as "fatigue" will perpetuate the debate.

The status of and future research into Myalgic Encephalomyelitis and Chronic Fatigue Syndrome: the need of accurate diagnosis, objective assessment, and acknowledging biological and clinical subgroups.

Although Myalgic Encephalomyelitis (ME) and Chronic Fatigue Syndrome (CFS) are used interchangeably, the diagnostic criteria define two distinct clinical entities. Cognitive impairment, (muscle) weakness, circulatory disturbances, marked variability of symptoms, and, above all, post-exertional malaise: a long-lasting increase of symptoms after a minor exertion, are distinctive symptoms of ME. This latter phenomenon separates ME, a neuro-immune illness, from chronic fatigue (syndrome), other disorders and deconditioning. The introduction of the label, but more importantly the diagnostic criteria for CFS have generated much confusion, mostly because chronic fatigue is a subjective and ambiguous notion. CFS was redefined in 1994 into unexplained (persistent or relapsing) chronic fatigue, accompanied by at least four out of eight symptoms, e.g., headaches and unrefreshing sleep. Most of the research into ME and/or CFS in the last decades was based upon the multivalent CFS criteria, which define a heterogeneous patient group. Due to the fact that fatigue and other symptoms are non-discriminative, subjective experiences, research has been hampered. Various authors have questioned the physiological nature of the symptoms and qualified ME/CFS as somatization. However, various typical symptoms can be assessed objectively using standardized methods. Despite subjective and unclear criteria and measures, research has observed specific abnormalities in ME/CFS repetitively, e.g., immunological abnormalities, oxidative and nitrosative stress, neurological anomalies, circulatory deficits and mitochondrial dysfunction. However, to improve future research standards and patient care, it is crucial that patients with post-exertional malaise (ME) and patients without this odd phenomenon are acknowledged as separate clinical entities that the diagnosis of ME and CFS in research and clinical practice is based upon accurate criteria and an objective assessment of characteristic symptoms, as much as possible that well-defined clinical and biological subgroups of ME and CFS patients are investigated in more detail, and that patients are monitored before, during and after interventions with objective measures and biomarkers.

Inflammatory and cell-mediated immune biomarkers in myalgic encephalomyelitis/chronic fatigue syndrome and depression: inflammatory markers are higher in myalgic encephalomyelitis/chronic fatigue syndrome than in depression.

BACKGROUND: Depression is an inflammatory disorder while many authors declare myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) to be a functional disorder. The aim of the present study is to compare inflammatory and cell-mediated immune (CMI) responses between depression and ME/CFS. METHODS: We measured two proinflammatory cytokines (PICs) in plasma, interleukin-1 (IL-1) and tumor necrosis factor-α (TNF-α), with enzyme-linked immunosorbent assays, and serum neopterin with a radioimmunoassay in controls, ME/CFS and depressive patients. RESULTS: Plasma PICs were significantly higher in ME/CFS than in depression and higher in both patient groups than in controls. Increased PIC levels in depression were attributable to the presence of fatigue and physio-somatic symptoms. Serum neopterin did not differ significantly between depression and ME/CFS but was higher in both patient groups than in controls. The significant positive correlations between neopterin and either IL-1 or TNF-α were significantly greater in depression than in ME/CFS. CONCLUSIONS: Since PICs cause depression-like behaviors and fatigue/malaise, we suggest that inflammation may play a role in the pathophysiology of ME/CFS and depression. Increased neopterin also seems to contribute to the pathophysiology of both disorders. This study has detected a shared 'pathway phenotype', i.e. disorders in inflammatory and CMI pathways, which underpins both ME/CFS and depression and, therefore, may explain the co-occurrence of both disorders. ME/CFS and depression are discriminated from each other by increased PICs in ME/CFS and differences in the immune cell communication networks.

IgM-mediated autoimmune responses directed against anchorage epitopes are greater in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) than in major depression.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and depression are considered to be neuro-immune disorders (Maes and Twisk, BMC Medicine 8:35, 2010). There is also evidence that depression and ME/CFS are accompanied by oxidative and nitrosative stress (O&NS) and by increased autoantibodies to a number of self-epitopes some of which have become immunogenic due to damage by O&NS. The aim of this study is to examine IgM-mediated autoimmune responses to different self-epitopes in ME/CFS versus depression. We examined serum IgM antibodies to three anchorage molecules (palmitic and myristic acid and S-farnesyl-L-cysteine); acetylcholine; and conjugated NO-modified adducts in 26 patients with major depression; 16 patients with ME/CFS, 15 with chronic fatigue; and 17 normal controls. Severity of fatigue and physio-somatic (F&S) symptoms was measured with the Fibromyalgia and Chronic Fatigue Syndrome Rating Scale. Serum IgM antibodies to the three anchorage molecules and NO-phenylalanine were significantly higher in ME/CFS than in depression. The autoimmune responses to oxidatively, but not nitrosatively, modified self-epitopes were significantly higher in ME/CFS than in depression and were associated with F&S symptoms. The autoimmune activity directed against conjugated acetylcholine did not differ significantly between ME/CFS and depression, but was greater in the patients than controls. Partially overlapping pathways, i.e. increased IgM antibodies to a multitude of neo-epitopes, underpin both ME/CFS and depression, while greater autoimmune responses directed against anchorage molecules and oxidatively modified neo-epitopes discriminate patients with ME/CFS from those with depression. These autoimmune responses directed against neoantigenic determinants may play a role in the dysregulation of key cellular functions in both disorders, e.g. intracellular signal transduction, cellular differentiation and apoptosis, but their impact may be more important in ME/CFS than in depression.

Myalgic Encephalomyelitis (ME), Chronic Fatigue Syndrome (CFS), and Chronic Fatigue (CF) are distinguished accurately: results of supervised learning techniques applied on clinical and inflammatory data.

There is much debate on the diagnostic classification of Myalgic Encephalomyelitis (ME), Chronic Fatigue Syndrome (CFS) and chronic fatigue (CF). Post-exertional malaise (PEM) is stressed as a key feature. This study examines whether CF and CFS, with and without PEM, are distinct diagnostic categories. Fukuda's criteria were used to diagnose 144 patients with chronic fatigue and identify patients with CFS and CF, i.e. those not fulfilling the Fukuda's criteria. PEM was rated by means of a scale with defined scale steps between 0 and 6. CFS patients were divided into those with PEM lasting more than 24h (labeled: ME) and without PEM (labeled: CFS). The 12-item Fibromyalgia and Chronic Fatigue Syndrome (FF) Rating Scale was used to measure severity of illness. Plasma interleukin-1 (IL-1), tumor necrosis factor (TNF)α, and lysozyme, and serum neopterin were employed as external validating criteria. Using fatigue, a subjective feeling of infection and PEM we found that ME, CFS, and CF were distinct categories. Patients with ME had significantly higher scores on concentration difficulties and a subjective experience of infection, and higher levels of IL-1, TNFα, and neopterin than patients with CFS. These biomarkers were significantly higher in ME and CFS than in CF patients. PEM loaded highly on the first two factors subtracted from the data set, i.e. "malaise-sickness" and "malaise-hyperalgesia". Fukuda's criteria are adequate to make a distinction between ME/CFS and CF, but ME/CFS patients should be subdivided into ME (with PEM) and CFS (without PEM).

Increased IgA responses to the LPS of commensal bacteria is associated with inflammation and activation of cell-mediated immunity in chronic fatigue syndrome.

BACKGROUND: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is accompanied by a) systemic IgA/IgM responses against the lipopolysaccharides (LPS) of commensal bacteria; b) inflammation, e.g. increased plasma interleukin-(IL)1 and tumor necrosis factor (TNF)α; and c) activation of cell-mediated immunity (CMI), as demonstrated by increased neopterin. METHODS: To study the relationships between the IgA/IgM responses to the LPS of microbiota, inflammation, CMI and the symptoms of ME/CFS we measured the IgA/IgM responses to the LPS of 6 different enterobacteria, serum IL-1, TNFα, neopterin, and elastase in 128 patients with ME/CFS and chronic fatigue (CF). Severity of symptoms was assessed by the Fibromyalgia and Chronic Fatigue Syndrome (FF) Rating Scale. RESULTS: Serum IL-1, TNFα, neopterin and elastase are significantly higher in patients with ME/CFS than in CF patients. There are significant and positive associations between the IgA responses to LPS and serum IL-1, TNFα, neopterin and elastase. Patients with an abnormally high IgA response show increased serum IL-1, TNFα and neopterin levels, and higher ratings on irritable bowel syndrome (IBS) than subjects with a normal IgA response. Serum IL-1, TNFα and neopterin are significantly related to fatigue, a flu-like malaise, autonomic symptoms, neurocognitive disorders, sadness and irritability. CONCLUSIONS: The findings show that increased IgA responses to commensal bacteria in ME/CFS are associated with inflammation and CMI activation, which are associated with symptom severity. It is concluded that increased translocation of commensal bacteria may be responsible for the disease activity in some ME/CFS patients.

Evidence for inflammation and activation of cell-mediated immunity in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): increased interleukin-1, tumor necrosis factor-α, PMN-elastase, lysozyme and neopterin.

BACKGROUND: There is evidence that inflammatory pathways and cell-mediated immunity (CMI) play an important role in the pathophysiology of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Activation of inflammatory and CMI pathways, including increased levels of cytokines, is known to induce fatigue and somatic symptoms. Given the broad spectrum inflammatory state in ME/CFS, the aim of this study was to examine whether inflammatory and CMI biomarkers are increased in individuals with ME/CFS. METHODS: In this study we therefore measured plasma interleukin-(IL)1, tumor necrosis factor (TNF)α, and PMN-elastase, and serum neopterin and lysozyme in 107 patients with ME/CFS, 37 patients with chronic fatigue (CF), and 20 normal controls. The severity of ME/CFS was measured with the Fibromyalgia and Chronic Fatigue Syndrome (FF) Rating Scale. RESULTS: Serum IL-1, TNFα, neopterin and lysozyme are significantly higher in patients with ME/CFS than in controls and CF patients. Plasma PMN-elastase is significantly higher in patients with ME/CFS than in controls and CF patients and higher in the latter than in controls. Increased IL-1 and TNFα are significantly correlated with fatigue, sadness, autonomic symptoms, and a flu-like malaise; neopterin is correlated with fatigue, autonomic symptoms, and a flu-like malaise; and increased PMN-elastase is correlated with concentration difficulties, failing memory and a subjective experience of infection. CONCLUSIONS: The findings show that ME/CFS is characterized by low-grade inflammation and activation of CMI. The results suggest that characteristic symptoms of ME/CFS, such as fatigue, autonomic symptoms and a flu-like malaise, may be caused by inflammatory mediators, e.g. IL-1 and TNFα.

Chronic fatigue syndrome: Harvey and Wessely's (bio)psychosocial model versus a bio(psychosocial) model based on inflammatory and oxidative and nitrosative stress pathways.

BACKGROUND: In a recently published paper, Harvey and Wessely put forward a 'biopsychosocial' explanatory model for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), which is proposed to be applicable to (chronic) fatigue even when apparent medical causes are present. METHODS: Here, we review the model proposed by Harvey and Wessely, which is the rationale for behaviourally oriented interventions, such as cognitive behaviour therapy (CBT) and graded exercise therapy (GET), and compare this model with a biological model, in which inflammatory, immune, oxidative and nitrosative (IO&NS) pathways are key elements. DISCUSSION: Although human and animal studies have established that the pathophysiology of ME/CFS includes IO&NS pathways, these abnormalities are not included in the model proposed by Harvey and Wessely. Activation of IO&NS pathways is known to induce fatigue and somatic (F&S) symptoms and can be induced or maintained by viral and bacterial infections, physical and psychosocial stressors, or organic disorders such as (auto)immune disorders. Studies have shown that ME/CFS and major depression are both clinical manifestations of shared IO&NS pathways, and that both disorders can be discriminated by specific symptoms and unshared or differentiating pathways. Interventions with CBT/GET are potentially harmful for many patients with ME/CFS, since the underlying pathophysiological abnormalities may be intensified by physical stressors. CONCLUSIONS: In contrast to Harvey and Wessely's (bio)psychosocial model for ME/CFS a bio(psychosocial) model based upon IO&NS abnormalities is likely more appropriate to this complex disorder. In clinical practice, we suggest physicians should also explore the IO&NS pathophysiology by applying laboratory tests that examine the pathways involved.

A review on cognitive behavorial therapy (CBT) and graded exercise therapy (GET) in myalgic encephalomyelitis (ME) / chronic fatigue syndrome (CFS): CBT/GET is not only ineffective and not evidence-based, but also potentially harmful for many patients with ME/CFS.

Benign Myalgic Encephalomyelitis (ME) / Chronic Fatigue Syndrome (CFS) is a debilitating disease which, despite numerous biological abnormalities has remained highly controversial. Notwithstanding the medical pathogenesis of ME/CFS, the (bio)psychosocial model is adopted by many governmental organizations and medical profes-sio-nals to legitimize the combination of Cognitive Behavioral Therapy (CBT) and Graded Exercise Therapy (GET) for ME/CFS. Justified by this model CBT and GET aim at eliminating presumed psychogenic and socially induced maintaining factors and reversing deconditioning, respectively. In this review we invalidate the (bio)psychosocial model for ME/CFS and demonstrate that the success claim for CBT/GET to treat ME/CFS is unjust. CBT/GET is not only hardly more effective than non-interventions or standard medical care, but many patients report that the therapy had affected them adversely, the majority of them even reporting substantial deterioration. Moreover, this review shows that exertion and thus GET most likely have a negative impact on many ME/CFS patients. Exertion induces post-exertional malaise with a decreased physical performan-ce/aerobic capacity, increased muscoskeletal pain, neurocognitive impairment, "fatigue", and weakness, and a long lasting "recovery" time. This can be explained by findings that exertion may amplify pre-existing pa-thophysiological abnormalities underpinning ME/CFS, such as inflammation, immune dysfunction, oxidative and nitrosative stress, channelopathy, defec-tive stress response mechanisms and a hypoactive hypothalamic-pituitary-adrenal axis. We conclude that it is unethical to treat patients with ME/CFS with ineffective, non-evidence-based and potentially harmful "rehabilitation therapies", such as CBT/GET.