Tag: review

Viral infections in chronic fatigue syndrome

Abstract:

Chronic fatigue syndrome (CFS) is a heterogeneous illness in which patients can have different, overlapping signs and symptoms. No single underlying cause has been established for all CFS patients. Epidemiological studies reveal that a flu-like sickness precedes the onset in the majority of cases. The major hypothesis of the pathogenesis of CFS is that infectious agents such as viruses, may trigger and lead to chronic activation of the immune system with abnormal regulation of cytokine production. Many studies have been performed to identify the possible microbial triggers and to understand the epidemiological microbial agents. We have summarized the recent progressive literature of virus, rickettsia, and mycoplasma implicated in the pathogenesis of CFS.

 

Source: Sairenji T, Nagata K. Viral infections in chronic fatigue syndrome. Nihon Rinsho. 2007 Jun;65(6):991-6. [Article in Japanese] https://www.ncbi.nlm.nih.gov/pubmed/17561687

 

Overview of chronic fatigue syndrome focusing on prevalence and diagnostic criteria

Abstract:

Chronic fatigue syndrome (CFS) is an operational concept proposed by Centers for Disease Control and Prevention to clarify the unknown etiology of the syndrome characterized by the sensation of abnormally prolonged fatigue. Lots of investigators reported various abnormalities such as virus infection, immune abnormalities, HPA axis abnormalities, metabolic abnormalities, etc., but there are a few abnormalities common to vast majority cases of CFS. Therefore, lots of people as well as medical doctors are still skeptical about the presence of CFS.

However, recent studies reveal that CFS can be understood to be a special condition based on the abnormality of neuroendocrine-immunologic system caused by the psycho-social stress and some genetic components. Under these conditions, a reactivation of various kinds of herpes virus infections and/or chronic infections might occur as a result of immune dysfunction, causing the abnormal production of several cytokines. A distinctive feature of CFS is thought to be the secondary brain dysfunction caused by the abnormal production of several cytokines. In this paper, I show the overview of CFS focusing around prevalence, economic impact and diagnostic criteria in Japan.

 

Source: Kuratsune H. Overview of chronic fatigue syndrome focusing on prevalence and diagnostic criteria. Nihon Rinsho. 2007 Jun;65(6):983-90. [Article in Japanese] https://www.ncbi.nlm.nih.gov/pubmed/17561686

 

History of chronic fatigue syndrome

Abstract:

Chronic fatigue syndrome (CFS) is not a new disease. Similar morbidities have been known as different names since past several centuries. For example, neurasthenia, epidemic neuromyasthenia, myalgic encephalomyelitis, Akureyri disease, Royal Free disease, chronic EBV disease, post-viral fatigue syndrome etc. Much of the recent interest in CFS was generated by incidence of infection-like outbreak at Lake Tahoe in Nevada. The Center for Disease Control (USA) realized that correlation was poor between those patients who had virologic evidence of EBV infection and those who had the symptoms of chronic fatigue. This is a review of the history of CFS. (1) Historical perspectives in chronic fatigue cases in past old period, (2) Post-viral infectious fatigue and chronic fatigue (myalgic encephalomyelitis), (3) Recent trend of CFS studies and its clinical similar situation. Finally, I would like to state that we intend to draw up a new diagnostic guideline for CFS in Japan.

 

Source: Hashimoto N. History of chronic fatigue syndrome. Nihon Rinsho. 2007 Jun;65(6):975-82. [Article in Japanese] https://www.ncbi.nlm.nih.gov/pubmed/17561685

 

The hypothalamo-pituitary-adrenal axis in chronic fatigue syndrome and fibromyalgia syndrome

Abstract:

The hypothalamo-pituitary-adrenal (HPA) axis plays a major role in the regulation of responses to stress. Human stress-related disorders such as chronic fatigue syndrome (CFS), fibromyalgia syndrome (FMS), chronic pelvic pain and post-traumatic stress disorder are characterized by alterations in HPA axis activity. However, the role of the HPA axis alterations in these stress-related disorders is not clear.

Most studies have shown that the HPA axis is underactive in the stress-related disorders, but contradictory results have also been reported, which may be due to the patients selected for the study, the methods used for the investigation of the HPA axis, the stage of the syndrome when the tests have been done and the interpretation of the results.

There is no structural abnormality in the endocrine organs which comprise the HPA axis, thus it seems that hypocortisolemia found in the patients with stress-related disorder is functional. It may be also an adaptive response of the body to chronic stress. In this review, tests used in the assessment of HPA axis function and the HPA axis alterations found in CFS and FMS are discussed in detail.

 

Source: Tanriverdi F, Karaca Z, Unluhizarci K, Kelestimur F. The hypothalamo-pituitary-adrenal axis in chronic fatigue syndrome and fibromyalgia syndrome. Stress. 2007 Mar;10(1):13-25. https://www.ncbi.nlm.nih.gov/pubmed/17454963

 

Infection and vaccination in chronic fatigue syndrome: myth or reality?

Abstract:

Chronic fatigue syndrome (CFS) is characterized by severe disabling fatigue lasting for more than 6 months associated with physical and mental disturbances such as headache, arthralgia, myalgia, memory impairment, sore throat and tender lymph nodes. The exact pathogenesis is still unknown. Several models were proposed to explain its etiology including chronic infection, endocrine dysfunction, autonomic imbalance, depression, decreased immunity states and an aberrant reaction to infection. No convincing evidence was found to support any of the suggested pathogenic mechanisms.

The current concept is that CFS pathogenesis is a multi factorial condition in which an infective agent cause an aberrant immune response characterized by a shift to Th-2 dominant response. When the response fails to be switched-off, a chronic immune activation occurs and clinically expressed as the symptomatology of CFS. Vaccinations are used in order to stimulate the immune system to induce a persistent immunity against the favorable antigens.

Several syndromes that contain chronic fatigue as one of their symptoms, such as “Gulf war syndrome” and macrophagic myofasciitis were related to vaccinations. Can vaccinations induce the aberrant immune response of CFS? Little is known about this issue. There are some reports on CFS occurring after vaccination, but few prospective and retrospective studies failed to find such an association. A working group of the Canadian Laboratory Center for Disease Control (LCDC) that was founded in order to examine the suspected association between CFS and vaccinations concluded that there is no evidence that relates CFS to vaccination.

Further studies are requested to examine this issue since it is very conceivable that if infection can lead to CFS, vaccination may also lead to it in the same immune-mediated pathogenesis.

 

Source: Appel S, Chapman J, Shoenfeld Y. Infection and vaccination in chronic fatigue syndrome: myth or reality? Autoimmunity. 2007 Feb;40(1):48-53. https://www.ncbi.nlm.nih.gov/pubmed/17364497

 

Is human herpesvirus-6 a trigger for chronic fatigue syndrome?

Abstract:

Chronic fatigue syndrome (CFS) is an illness currently defined entirely by a combination of non-specific symptoms. Despite this subjective definition, CFS is associated with objective underlying biological abnormalities, particularly involving the nervous system and immune system.

Most studies have found that active infection with human herpesvirus-6 (HHV-6)–a neurotropic, gliotropic and immunotropic virus–is present more often in patients with CFS than in healthy control and disease comparison subjects, yet it is not found in all patients at the time of testing. Moreover, HHV-6 has been associated with many of the neurological and immunological findings in patients with CFS.

Finally, CFS, multiple sclerosis and seizure disorders share some clinical and laboratory features and, like CFS, the latter two disorders also are being associated increasingly with active HHV-6 infection. Therefore, it is plausible that active infection with HHV-6 may trigger and perpetuate CFS in a subset of patients.

 

Source: Komaroff AL. Is human herpesvirus-6 a trigger for chronic fatigue syndrome? J Clin Virol. 2006 Dec;37 Suppl 1:S39-46. https://www.ncbi.nlm.nih.gov/pubmed/17276367

 

Cognitive dysfunction in fibromyalgia and chronic fatigue syndrome: new trends and future directions

Abstract:

Fibromyalgia (FM) and chronic fatigue syndrome (CFS) patients often have memory and cognitive complaints. Objective cognitive testing demonstrates long-term and working memory impairments. In addition, CFS patients have slow information-processing, and FM patients have impaired control of attention, perhaps due to chronic pain. Neuroimaging studies demonstrate cerebral abnormalities and a pattern of increased neural recruitment during cognitive tasks. Future work should focus on the specific neurocognitive systems involved in cognitive dysfunction in each syndrome.

 

Source: Glass JM. Cognitive dysfunction in fibromyalgia and chronic fatigue syndrome: new trends and future directions. Curr Rheumatol Rep. 2006 Dec;8(6):425-9. https://www.ncbi.nlm.nih.gov/pubmed/17092441

 

Interventions for the treatment, management and rehabilitation of patients with chronic fatigue syndrome/myalgic encephalomyelitis: an updated systematic review

Abstract:

OBJECTIVES: To determine whether any particular intervention or combination of interventions is effective in the treatment, management and rehabilitation of adults and children with a diagnosis of chronic fatigue syndrome / myalgic encephalomyelitis (CFS/ME).

DESIGN: Substantive update of a systematic review published in 2002. Randomized (RCTs) and non-randomized controlled trials of any intervention or combination of interventions were eligible for inclusion. Study participants could be adults or children with a diagnosis of CFS/ME based on any criteria. We searched eleven electronic databases, reference lists of articles and reviews, and textbooks on CFS/ME. Additional references were sought by contact with experts.

RESULTS: Seventy studies met the inclusion criteria. Studies on behavioural, immunological, pharmacological and complementary therapies, nutritional supplements and miscellaneous other interventions were identified. Graded exercise therapy and cognitive behaviour therapy appeared to reduce symptoms and improve function based on evidence from RCTs. For most other interventions, evidence of effectiveness was inconclusive and some interventions were associated with significant adverse effects.

CONCLUSIONS: Over the last five years, there has been a marked increase in the size and quality of the evidence base on interventions for CFS/ME. Some behavioural interventions have shown promising results in reducing the symptoms of CFS/ME and improving physical functioning. There is a need for research to define the characteristics of patients who would benefit from specific interventions and to develop clinically relevant objective outcome measures.

Comment in: Chronic fatigue syndrome. [J R Soc Med. 2007]

 

Source: Chambers D, Bagnall AM, Hempel S, Forbes C. Interventions for the treatment, management and rehabilitation of patients with chronic fatigue syndrome/myalgic encephalomyelitis: an updated systematic review. J R Soc Med. 2006 Oct;99(10):506-20. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1592057/ (Full article)

 

Conceptual issues in undifferentiated somatoform disorder and chronic fatigue syndrome

Abstract:

PURPOSE OF REVIEW: To review the conceptual problems in distinguishing between undifferentiated somatoform disorder and chronic fatigue syndrome, for both may present with fatigue as the main symptom.

RECENT FINDINGS: The differences and/or similarities between undifferentiated somatoform disorder and chronic fatigue syndrome have not been studied, conceptually or empirically. The literature fails to present discriminant validity of chronic fatigue syndrome in relation to undifferentiated somatoform disorder. A critical feature is implied in the definition of undifferentiated somatoform disorder but absent from the definitions of chronic fatigue syndrome: some patients experience their fatigue as being exclusively physical and not as mental, which is prima facie peculiar, for fatigue is necessarily a mental experience. One is not able to experience fatigue without a mind (or a brain). This experience is characterized as a ‘mindless’ fatigue, underpinned by pathological reductionist thinking. By not recognizing this critical feature, diagnostic endeavours may perpetuate the problem as a function of the patient’s difficulty.

SUMMARY: Proponents of chronic fatigue syndrome should distinguish chronic fatigue syndrome from undifferentiated somatoform disorder, if chronic fatigue syndrome is a distinct entity at all. Further, the ‘mindless’ quality is a critical feature that needs consideration in refining the concept of undifferentiated somatoform disorder.

 

Source: van Staden WC. Conceptual issues in undifferentiated somatoform disorder and chronic fatigue syndrome. Curr Opin Psychiatry. 2006 Nov;19(6):613-8. https://www.ncbi.nlm.nih.gov/pubmed/17012941

 

Chronic fatigue syndrome

Abstract:

Chronic fatigue syndrome (CFS) is thought to have a worldwide prevalence of 0.4-1% with approximately 240,000 patients in the UK. Diagnosis is based on clinical criteria and critically depends on exclusion of other physical and psychiatric diseases. Studies of pathogenesis have revealed immune system abnormalities and chronic immune activation, dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis, brain abnormalities, evidence of emotional stress (comprising host aspects) and evidence of exogenous insults, for example, various microbial infections (Epstein-Barr virus, enteroviruses, parvovirus B19, Coxiella burnetii and Chlamydia pneumoniae), vaccinations and exposure to organophosphate chemicals and other toxins (comprising environmental aspects).

Emotional stress appears to be very important as it reduces the ability of the immune system to clear infections, its presence has been shown to determine whether or not an individual develops symptoms upon virus infection, and it leads to activation of the HPA axis. But, emotional stress is distinct from depression, the presence of which precludes a diagnosis of CFS. There is no specific treatment for CFS other than the much underutilised approach of specific treatment of virus infections. Current priorities are to understand the molecular pathogenesis of disease in terms of human and virus gene expression, to develop a diagnostic test based on protein biomarkers, and to develop specific curative treatments.

 

Source: Devanur LD, Kerr JR. Chronic fatigue syndrome.  J Clin Virol. 2006 Nov;37(3):139-50. Epub 2006 Sep 15. https://www.ncbi.nlm.nih.gov/pubmed/16978917