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

Separating Patients with SEID from Those with CFS in the French ME/CFS Association, with Some Thoughts on Nomenclature

In 2015, the American Institute of Medicine, now called the National Academy of Medicine, (IOM/NAM) proposed new diagnostic criteria for both Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and a new label: Systemic Exertion Intolerance Disease (SEID). This study aimed to evaluate the SEID criteria among members of the French Association of ME/CFS (ASFC) and their opinion about this new name. We sent an anonymous questionnaire to 494 ASFC members, using French-translated questions derived from the IOM/NAM tool kit. Among the 178/231 responding subjects who reported ME/CFS diagnosis, 150 (84%) met the criteria of SEID. For each set of questions, we identified some of them that significantly distinguished SEID from non-SEID patients concerning unrefreshing sleep, cognitive disorders, and orthostatic intolerance items. Forty-six percent of the respondents considered the “SEID” terminology as more appropriate than “CFS”, 39% considered it inappropriate, and 15% had no opinion. Some questions better identified the SEID criteria. The IOM/NAM SEID criteria captured a large part of ASFC members suffering from ME/CFS. However, this new SEID label was not well accepted by the subjects, nor were the other denominations, suggesting that a better term should be found. Pending development of specific markers, further work with patient communities is needed to find a more suitable label.

Patients with Persistent Polyclonal B-Cell Lymphocytosis Share the Symptomatic Criteria of Systemic Exertion Intolerance Disease

Introduction: Persistent polyclonal B-cell lymphocytosis (PPBL) is a rare and still poorly understood entity, with 90% of cases occurring in female smokers. Patients often appear tired and in pain, but the clinical symptoms remain imprecise. The main risk is the development of lymphoma in some cases. To better understand the characteristics of the fatigue associated with PPBL and study its relationship with systemic exertion intolerance disease (SEID), we analyzed the symptoms in a cohort of patients with PPBL included in the French national registry. Material and methods: An anonymous questionnaire following the recommendations of the Institute of Medicine/National Academy of Medicine for screening of the new SEID criteria was created in French and mailed to 50 patients. Results: Thirty-nine (78%) contacted patients responded. The studied population was mainly constituted of women (90%) with an average age of 50 (18–59) years. Smoking was a constant factor in all patients. A total of 28/39 (72%) respondents met the SEID symptoms criteria. Severe chronic fatigue for more than 6 months was noted in 36/39 cases (92%). Unrefreshing sleep, post-exertional malaise, cognitive impairment, and orthostatic intolerance were described in 30/39 (77%), 32/39 (82%), 28/39 (72%), and 27/39 (69%) cases, respectively. Pain (arthralgia, myalgia, headache) was present in 26/39 (67%) cases. The most prominent SEID symptoms were fatigue, followed by post-exercise discomfort and cognitive difficulties. The most disabling symptom was non-restorative sleep, followed by pain. An inflammatory and/or autoimmune context was noted in 13 patients (33%), and these comorbidities could have favored the deterioration of the general condition. Three patients also presented with fibromyalgia. However, 3 patients did not mention any complaints. Conclusion: This survey indicated that patients with PPBL most often initially presented with disabling chronic fatigue, chronic pain, and other symptoms suggestive of SEID but requiring more studies to confirm it. Education of medical staff about the symptoms of PPBL should be encouraged to better assess this peculiar condition.

The Enterovirus Theory of Disease Etiology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Critical Review

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex, multi-system disease whose etiological basis has not been established. Enteroviruses (EVs) as a cause of ME/CFS have sometimes been proposed, as they are known agents of acute respiratory and gastrointestinal infections that may persist in secondary infection sites, including the central nervous system, muscle, and heart. To date, the body of research that has investigated enterovirus infections in relation to ME/CFS supports an increased prevalence of chronic or persistent enteroviral infections in ME/CFS patient cohorts than in healthy individuals. Nevertheless, inconsistent results have fueled a decline in related studies over the past two decades. This review covers the aspects of ME/CFS pathophysiology that are consistent with a chronic enterovirus infection and critically reviews methodologies and approaches used in past EV-related ME/CFS studies. We describe the prior sample types that were interrogated, the methods used and the limitations to the approaches that were chosen. We conclude that there is considerable evidence that prior outbreaks of ME/CFS were caused by one or more enterovirus groups. Furthermore, we find that the methods used in prior studies were inadequate to rule out the presence of chronic enteroviral infections in individuals with ME/CFS. Given the possibility that such infections could be contributing to morbidity and preventing recovery, further studies of appropriate biological samples with the latest molecular methods are urgently needed.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Comprehensive Review

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating chronic disease of unknown aetiology that is recognized by the World Health Organization (WHO) and the United States Center for Disease Control and Prevention (US CDC) as a disorder of the brain. The disease predominantly affects adults, with a peak age of onset of between 20 and 45 years with a female to male ratio of 3:1. Although the clinical features of the disease have been well established within diagnostic criteria, the diagnosis of ME/CFS is still of exclusion, meaning that other medical conditions must be ruled out. The pathophysiological mechanisms are unclear but the neuro-immuno-endocrinological pattern of CFS patients gleaned from various studies indicates that these three pillars may be the key point to understand the complexity of the disease. At the moment, there are no specific pharmacological therapies to treat the disease, but several studies' aims and therapeutic approaches have been described in order to benefit patients' prognosis, symptomatology relief, and the recovery of pre-existing function. This review presents a pathophysiological approach to understanding the essential concepts of ME/CFS, with an emphasis on the population, clinical, and genetic concepts associated with ME/CFS.

Could disease labelling have positive effects? An experimental study exploring the effect of the chronic fatigue syndrome label on intended social support

Objective Chronic fatigue syndrome (CFS) patients report limited social support, which can affect symptom severity. Friends are a key source of social support for young adults with CFS, but there is limited research on friends' responses to the CFS label. We explored the potential benefits or harms of the CFS label for shaping the potential for social support from a friend's perspective. Method 207 university students responded to hypothetical scenarios about a close friend experiencing CFS. Participants were randomly allocated to either the CFS-label or no-label conditions. The potential for social support was operationalised as attitude (sympathetic or hostile), intended treatment support and intended behavioural support. Results The CFS label elicited a greater potential for social support, with significantly higher sympathetic responses, lower rejecting responses and greater support for active treatment. These effects were significantly greater in men compared to women. There was no effect on intended behavioural support. Conclusion This study suggests the CFS label may increase the potential for social support. Young adults, particularly men, held more supportive attitudes towards their friend when the CFS label was used. Practical Implications The effects of labels on the potential for social support need to be considered when evaluating the usefulness of a disease label.

Unexpected findings and promoting monocausal claims, a cautionary tale

Stories of serendipitous discoveries in medicine incorrectly imply that the path from an unexpected observation to major discovery is straightforward or guaranteed. In this paper, I examine a case from the field of research about chronic fatigue syndrome (CFS). In Norway, an unexpected positive result during clinical care has led to the development of a research programme into the potential for the immunosuppressant drug rituximab to relieve the symptoms of CFS. The media and public have taken up researchers' speculations that their research results indicate a causal mechanism for CFS - consequently, patients now have great hope that 'the cause' of CFS has been found, and thus, a cure is sure to follow. I argue that a monocausal claim cannot be correctly asserted, either on the basis of the single case of an unexpected, although positive, result or on the basis of the empirical research that has followed up on that result. Further, assertion and promotion of this claim will have specific harmful effects: it threatens to inappropriately narrow the scope of research on CFS, might misdirect research altogether, and could directly and indirectly harm patients. Therefore, the CFS case presents a cautionary tale, illustrating the risks involved in drawing a theoretical hypothesis from an unexpected observation. Further, I draw attention to the tendency in contemporary clinical research with CFS to promote new research directions on the basis of reductive causal models of that syndrome. Particularly, in the case of CFS research, underdetermination and causal complexity undermine the potential value of a monocausal claim. In sum, when an unexpected finding occurs in clinical practice or medical research, the value of following up on that finding is to be found not in the projected value of a singular causal relationship inferred from the finding but rather in the process of research that follows.

Muscle injections with lidocaine improve resting fatigue and pain in patients with chronic fatigue syndrome

OBJECTIVE

Patients with chronic fatigue syndrome (CFS) complain of long-lasting fatigue and pain which are not relieved by rest and worsened by physical exertion. Previous research has implicated metaboreceptors of muscles to play an important role for chronic fatigue and pain. Therefore, we hypothesized that blocking impulse input from deep tissues with intramuscular lidocaine injections would improve not only the pain but also fatigue of CFS patients.

METHODS

In a double-blind, placebo-controlled study, 58 CFS patients received 20 mL of 1% lidocaine (200 mg) or normal saline once into both trapezius and gluteal muscles. Study outcomes included clinical fatigue and pain, depression, and anxiety. In addition, mechanical and heat hyperalgesia were assessed and serum levels of lidocaine were obtained after the injections.

RESULTS

Fatigue ratings of CFS patients decreased significantly more after lidocaine compared to saline injections (p = 0.03). In contrast, muscle injections reduced pain, depression, and anxiety (p < 0.001), but these changes were not statistically different between lidocaine and saline (p > 0.05). Lidocaine injections increased mechanical pain thresholds of CFS patients (p = 0.04) but did not affect their heat hyperalgesia. Importantly, mood changes or lidocaine serum levels did not significantly predict fatigue reductions.

CONCLUSION

These results demonstrate that lidocaine injections reduce clinical fatigue of CFS patients significantly more than placebo, suggesting an important role of peripheral tissues for chronic fatigue. Future investigations will be necessary to evaluate the clinical benefits of such interventions.

Investigation of suspected chronic fatigue syndrome/myalgic encephalopathy

BACKGROUND

Chronic fatigue is a frequently occurring problem in both the primary and specialist health services. The Department of Neurology at Haukeland University Hospital has established a standard assessment for patients referred with suspected CFS/ME. This study reports diagnoses and findings upon assessment, and considers the benefit of supplementary examinations.

MATERIAL AND METHOD

Diagnoses and findings from examinations of 365 patients assessed for suspected CFS/ME are retrospectively reported.

RESULTS

A total of 48 patients (13.2%) were diagnosed with CFS/ME, while a further 18 patients (4.9%) were diagnosed with post-infectious fatigue. Mental and behavioural disorders were diagnosed in 169 patients (46.3%), and these represented by far the largest group. Serious, but unrecognised somatic illness was discovered in two patients, while changes of uncertain significance were identified by MRI and lumbar puncture in a few patients.

INTERPRETATION

Fatigue is a frequently occurring symptom in the population. Thorough somatic and psychiatric investigation is necessary before referral to the specialist health services. Mental disorders and reactions to life crises are common and important differential diagnoses for CFS/ME. Long waiting times in the specialist health services may result in delayed diagnosis for these patients.

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".