A Comprehensive Update of the Current Understanding of Chronic Fatigue Syndrome

Abstract:

This is a comprehensive literature review of chronic fatigue syndrome (CFS). We provide a description of the background, etiology, pathogenesis, diagnosis, and management regarding CFS. CFS is a multifaceted illness that has many symptoms and a wide array of clinical presentations.

As of recent, CFS has been merged with myalgic encephalomyelitis (ME). Much of the difficulty in its management has stemmed from a lack of a concrete understanding of its etiology and pathogenesis. There is a potential association between dysfunction of the autoimmune, neuroendocrine, or autonomic nervous systems and the development of CFS. Possible triggering events, such as infections followed by an immune dysregulation resulting have also been proposed. In fact, ME/CFS was first described following Epstein Barr virus (EBV) infections, but it was later determined that it was not always preceded by EBV infection.

Patient diagnosed with CFS have shown a noticeably earlier activation of anaerobic metabolism as a source of energy, which is suggestive of impaired oxygen consumption. The differential diagnoses range from tick-borne illnesses to psychiatric disorders to thyroid gland dysfunction. Given the many overlapping symptoms of CFS with other illnesses makes diagnosing it far from an easy task.

The Centers for Disease Control and Prevention (CDC) considers it a diagnosing of exclusion, stating that self-reported fatigue for at minimum of six months and four of the following symptoms are necessary for a proper diagnosis: memory problems, sore throat, post-exertion malaise, tender cervical or axillary lymph nodes, myalgia, multi-joint pain, headaches, and troubled sleep. In turn, management of CFS is just as difficult.

Treatment ranges from conservative, such as cognitive behavioral therapy (CBT) and antidepressants, to minimally invasive management. Minimally invasive management involving ranscutaneous electrical acupoint stimulation of target points has demonstrated significant improvement in fatigue and associated symptoms in a 2017 randomized controlled study. The understanding of CFS is evolving before us as we continue to learn more about it. As further reliable studies are conducted, providing a better grasp of what the syndrome encompasses, we will be able to improve our diagnosis and management of it.

Source: Noor N, Urits I, Degueure A, Rando L, Kata V, Cornett EM, Kaye AD, Imani F, Narimani-Zamanabadi M, Varrassi G, Viswanath O. A Comprehensive Update of the Current Understanding of Chronic Fatigue Syndrome. Anesth Pain Med. 2021 Jun 26;11(3):e113629. doi: 10.5812/aapm.113629. PMID: 34540633; PMCID: PMC8438707. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8438707/  (Full text)

Long COVID: Is it really myalgic encephalomyelitis? Bibliographic review and considerations

Abstract:

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.

Source: Espinosa Rodríguez, P et al. “COVID persistente: ¿es en realidad una encefalomielitis miálgica? Revisión bibliográfica y consideraciones” [Long COVID: Is it really myalgic encephalomyelitis? Bibliographic review and considerations]. Semergen, S1138-3593(21)00091-5. 13 Sep. 2021, doi:10.1016/j.semerg.2021.03.006 [Abstract in English, Spanish] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8437705/  (Full text)

Long COVID Patient Symptoms and its Evaluation and Management

Abstract:

While the acute case burdens and deaths from the COVID-19 pandemic (in Nepal approaching 700,000 and 10,000 respectively) have been costly, the characteristics and potentially huge dimensions of the chronic disease sequelae of this infectious disease are only slowly becoming apparent. We reviewed Pub Med, major medical meeting and medical journal, and investigative journalist materials seeking to frame and describe COVID-19 chronic disease.

The consequences of COVID-19 infections follow major organ damage, and induction of immunological and hormonal systems dysfunction. The first injuries are consequent to direct viral effects on tissues, and vasculitis, endothelialitis, thrombosis and inflammatory events. Pulmonary, cardiac, brain, and kidney tissues incur function-limiting damage, with dyspnea, arrythmias, decreased exercise capacity, cognitive dysfunction, and decreased glomerular filtration rates.

The second process is characterized by immune dysregulation and autoimmunity, and dysfunction of hormonal regulation systems, with high, fluctuating levels of physical and mental fatigue, multiple-site pain and ache, and non-restorative sleep, in 10-30% of cases.

This communication proposes evaluation and management of chronic COVID-19 patients with efficient assessment of commonest symptoms, targeted physical examination and organ function testing, and interventions based on specific organ functional status, and experience with similar chronic immune syndromes, such as myalgic encephalomyelitis.

Source: Sundar Shrestha D, Love R. Long COVID Patient Symptoms and its Evaluation and Management. JNMA J Nepal Med Assoc. 2021 Aug 12;59(240):823-831. doi: 10.31729/jnma.6355. PMID: 34508486. https://pubmed.ncbi.nlm.nih.gov/34508486/

Redox imbalance links COVID-19 and myalgic encephalomyelitis/chronic fatigue syndrome

Abstract:

Although most patients recover from acute COVID-19, some experience postacute sequelae of severe acute respiratory syndrome coronavirus 2 infection (PASC). One subgroup of PASC is a syndrome called “long COVID-19,” reminiscent of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). ME/CFS is a debilitating condition, often triggered by viral and bacterial infections, leading to years-long debilitating symptoms including profound fatigue, postexertional malaise, unrefreshing sleep, cognitive deficits, and orthostatic intolerance. Some are skeptical that either ME/CFS or long COVID-19 involves underlying biological abnormalities. However, in this review, we summarize the evidence that people with acute COVID-19 and with ME/CFS have biological abnormalities including redox imbalance, systemic inflammation and neuroinflammation, an impaired ability to generate adenosine triphosphate, and a general hypometabolic state.

These phenomena have not yet been well studied in people with long COVID-19, and each of them has been reported in other diseases as well, particularly neurological diseases. We also examine the bidirectional relationship between redox imbalance, inflammation, energy metabolic deficits, and a hypometabolic state. We speculate as to what may be causing these abnormalities. Thus, understanding the molecular underpinnings of both PASC and ME/CFS may lead to the development of novel therapeutics.

Source: Paul BD, Lemle MD, Komaroff AL, Snyder SH. Redox imbalance links COVID-19 and myalgic encephalomyelitis/chronic fatigue syndrome. Proc Natl Acad Sci U S A. 2021 Aug 24;118(34):e2024358118. doi: 10.1073/pnas.2024358118. PMID: 34400495. https://pubmed.ncbi.nlm.nih.gov/34400495/

Dysregulation of cellular energetics in Gulf War Illness

Abstract:

Gulf War Illness (GWI) is estimated to have affected about one third of the Veterans who participated in the first Persian Gulf War. The symptoms of GWI include chronic neurologic impairments, chronic fatigue syndrome, as well as fibromyalgia and immune system disorders, collectively referred to as chronic multi-symptom illness. Thirty years after the war, we still do not have an effective treatment for GWI. It is necessary to understand the molecular basis of the symptoms of GWI in order to develop appropriate therapeutic strategies. Cellular energetics are critical to the maintenance of cellular homeostasis, a process that is highly dependent on intact mitochondrial function and there is significant evidence from both human studies and animal models that mitochondrial impairments may lead to GWI symptoms.

The available clinical and pre-clinical data suggest that agents that improve mitochondrial function have the potential to restore cellular energetics and treat GWI. To date, the experiments conducted in animal models of GWI have mainly focused on neurobehavioral aspects of the illness. Additional studies to address the fundamental biological processes that trigger the dysregulation of cellular energetics in GWI are warranted to better understand the underlying pathology and to develop new treatment methods. This review highlights studies related to mitochondrial dysfunction observed in both GW veterans and in animal models of GWI.

Source: Raju RP, Terry AV. Dysregulation of cellular energetics in Gulf War Illness. Toxicology. 2021 Aug 10:152894. doi: 10.1016/j.tox.2021.152894. Epub ahead of print. PMID: 34389359. https://pubmed.ncbi.nlm.nih.gov/34389359/

ME/CFS: Past, Present and Future

Abstract:

This review raises a number of compelling issues related to the condition of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Some historical perspective is necessary in order to highlight the nature of the controversy concerning its causation. Throughout history, a pattern tends to repeat itself when natural phenomena require explanation. Dogma usually arrives first, then it is eventually replaced by scientific understanding. The same pattern is unfolding in relation to ME/CFS, but supporters of the psychological dogma surrounding its causation remain stubbornly resistant, even in the face of compelling scientific evidence to the contrary. Acceptance of the latter is not just an academic issue; the route to proper understanding and treatment of ME/CFS is through further scientific research rather than psychological theorisation. Only then will a long-suffering patient group benefit.

Source: Weir, William, and Nigel Speight. 2021. “ME/CFS: Past, Present and Future” Healthcare 9, no. 8: 984. https://doi.org/10.3390/healthcare9080984 https://www.mdpi.com/2227-9032/9/8/984/htm (Full text)

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

Abstract:

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.

Source: O’Neal AJ, Hanson MR. The Enterovirus Theory of Disease Etiology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Critical Review. Front Med (Lausanne). 2021 Jun 18;8:688486. doi: 10.3389/fmed.2021.688486. PMID: 34222292; PMCID: PMC8253308. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8253308/  (Full text)

Post-Acute COVID-19 Syndrome and the cardiovascular system: What is known?

Abstract:

Post-Acute COVID-19 Syndrome (PACS) is defined by persistent symptoms >3-4 weeks after onset of COVID-19. The mechanism of these persistent symptoms is distinct from acute COVID-19 although not completely understood despite the high incidence of PACS. Cardiovascular symptoms such as chest pain and palpitations commonly occur in PACS, but the underlying cause of symptoms is infrequently known. While autopsy studies have shown that the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) rarely causes direct myocardial injury, several syndromes such as myocarditis, pericarditis, and Postural Orthostatic Tachycardia Syndrome have been implicated in PACS. Additionally, patients hospitalized with acute COVID-19 who display biomarker evidence of myocardial injury may have underlying coronary artery disease revealed by the physiological stress of SARS-CoV-2 infection and may benefit from medical optimization. We review what is known about PACS and the cardiovascular system and propose a framework for evaluation and management of related symptoms.

Source: Dixit NM, Churchill A, Nsair A, Hsu JJ. Post-Acute COVID-19 Syndrome and the cardiovascular system: What is known? Am Heart J Plus. 2021 May;5:100025. doi: 10.1016/j.ahjo.2021.100025. Epub 2021 Jun 24. PMID: 34192289; PMCID: PMC8223036. https://pubmed.ncbi.nlm.nih.gov/34192289/

Migraine Is More Than Just Headache: Is the Link to Chronic Fatigue and Mood Disorders Simply Due to Shared Biological Systems?

Abstract:

Migraine is a symptomatically heterogeneous condition, of which headache is just one manifestation. Migraine is a disorder of altered sensory thresholding, with hypersensitivity among sufferers to sensory input. Advances in functional neuroimaging have highlighted that several brain areas are involved even prior to pain onset. Clinically, patients can experience symptoms hours to days prior to migraine pain, which can warn of impending headache. These symptoms can include mood and cognitive change, fatigue, and neck discomfort. Some epidemiological studies have suggested that migraine is associated in a bidirectional fashion with other disorders, such as mood disorders and chronic fatigue, as well as with other pain conditions such as fibromyalgia. This review will focus on the literature surrounding alterations in fatigue, mood, and cognition in particular, in association with migraine, and the suggested links to disorders such as chronic fatigue syndrome and depression.

We hypothesize that migraine should be considered a neural disorder of brain function, in which alterations in aminergic networks integrating the limbic system with the sensory and homeostatic systems occur early and persist after headache resolution and perhaps interictally. The associations with some of these other disorders may allude to the inherent sensory sensitivity of the migraine brain and shared neurobiology and neurotransmitter systems rather than true co-morbidity.

Source: Karsan N, Goadsby PJ. Migraine Is More Than Just Headache: Is the Link to Chronic Fatigue and Mood Disorders Simply Due to Shared Biological Systems? Front Hum Neurosci. 2021 Jun 3;15:646692. doi: 10.3389/fnhum.2021.646692. PMID: 34149377; PMCID: PMC8209296. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8209296/ (Full text)

Coenzyme Q 10: Clinical Applications beyond Cardiovascular Diseases

Abstract:

Coenzyme Q10 (CoQ10) is an essential cofactor in oxidative phosphorylation (OXPHOS), present in mitochondria and cell membranes in reduced and oxidized forms. Acting as an energy transfer molecule, it occurs in particularly high levels in the liver, heart, and kidneys. CoQ10 is also an anti-inflammatory and antioxidant agent able to prevent the damage induced by free radicals and the activation of inflammatory signaling pathways. In this context, several studies have shown the possible inverse correlation between the blood levels of CoQ10 and some disease conditions.

Interestingly, beyond cardiovascular diseases, CoQ10 is involved also in neuronal and muscular degenerative diseases, in migraine and in cancer; therefore, the supplementation with CoQ10 could represent a viable option to prevent these and in some cases might be used as an adjuvant to conventional treatments. This review is aimed to summarize the clinical applications regarding the use of CoQ10 in migraine, neurodegenerative diseases (including Parkinson and Alzheimer diseases), cancer, or degenerative muscle disorders (such as multiple sclerosis and chronic fatigue syndrome), analyzing its effect on patients’ health and quality of life.

Source: Testai L, Martelli A, Flori L, Cicero AFG, Colletti A. Coenzyme Q10: Clinical Applications beyond Cardiovascular Diseases. Nutrients. 2021 May 17;13(5):1697. doi: 10.3390/nu13051697. PMID: 34067632. https://pubmed.ncbi.nlm.nih.gov/34067632/