By Miriam E. Tucker, Medscape News, 05 August 2022
Emerging evidence is shedding light on the common underlying mechanisms contributing to the overlapping clinical phenomena of “long COVID,” myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), and dysautonomia.
At the virtual annual meeting of the International Association for Chronic Fatigue Syndrome / Myalgic Encephalomyelitis (IACFSME), speakers presented data showing similar pathophysiologic abnormalities in people with systemic symptoms associated with ME/CFS who had a prior SARS-CoV-2 infection and those who did not, including individuals whose illness preceded the COVID-19 pandemic.
Core clinical diagnostic criteria for ME/CFS established by the Institute of Medicine in 2015 include substantial decrement in functioning for 6 months or longer, post-exertional malaise, or a worsening of symptoms following even minor exertion (often described by patients as “crashes”), unrefreshing sleep, and cognitive dysfunction and/or orthostatic intolerance that are frequent and severe.
Long COVID has been defined in several different ways using different terminology. The US Centers for Disease Control and Prevention, for example, defines “post-COVID conditions” as those continuing four or more weeks beyond first symptoms. The World Health Organization's clinical case definition of “post COVID-19 condition” includes otherwise unexplained symptoms 3 months from COVID-19 onset and lasting longer than 2 months.
Both ME/CFS and long COVID commonly involve numerous symptoms beyond the defining ones, affecting nearly every organ system in the body, including systemic, neurocognitive, endocrine, cardiovascular, pulmonary, musculoskeletal, and gastrointestinal, with wide variation among individuals. Autonomic dysfunction is common to both conditions, particularly postural orthostatic tachycardia syndrome (POTS).
“My way of understanding these illnesses is that they're not just multisystem illnesses, but all these interactive systems that lean on each other are dysregulated… I would say that a very common underlying mediator of both ME/CFS and long COVID is autonomic dysfunction, and it presents as POTS…
“…if basic bioenergetics are disrupted and in an oxidative-stress state [then] they have downregulated energy production at the cellular level, which seems to be the case in ME/CFS and now in long COVID.”
Nancy Klimas, MD, director of the Institute for Neuro-Immune Medicine at Nova Southeastern University, Fort Lauderdale, Florida
New ICD-10 Codes Better Characterize the Syndromes
New ICD-10 codes for 2023, being implemented on October 1, will enable clinicians to better document all of these interrelated conditions. Under the existing G93.3, “Postviral and related fatigue syndromes,” there will now be:
- G93.31 – “Postviral fatigue syndrome”
- G93.32 – “Myalgic encephalomyelitis / chronic fatigue syndrome” (and the separate terms)
- G93.39 – “Other post infection and related fatigue syndromes”
The old R53.82, “Chronic fatigue, unspecified” code now excludes all of the above conditions. The additional code U09.9 for “post COVID-19 condition, unspecified,” may also be used if applicable. In addition, a new code for POTS, G90.A, which wasn't previously mentioned in ICD-10, may also be used starting October 1.
Lucinda Bateman, MD, founder and director of the Bateman Horne Center, Salt Lake City, Utah, advises using all applicable codes for a given patient.
“If a patient came into my office with long COVID and met criteria for ME/CFS, we would code both, and also any other syndrome criteria that they may meet, such as POTS or fibromyalgia.
“If people use the codes appropriately, then you can understand the overlap better. It increases the likelihood of reimbursement, creates a more accurate medical record for the patient, and provides them with a better tool should they require disability benefits.”
Lucinda Bateman, MD, founder and director of the Bateman Horne Center, Salt Lake City, Utah
Bateman advises in-office orthostatic evaluation for all patients with this symptom constellation, using a passive standing evaluation such as the 10-minute NASA Lean test.
“Clinicians should take the time to do orthostatic testing in these patients because it provides objective markers and will help lead us to potential interventions to help improve people's function.”
Immune System Dysfunction Appears to Underlie Many Cases
In a keynote address during the conference, Akiko Iwasaki, PhD, of Yale University, New Haven, Connecticut, pointed out that long COVID and ME/CFS are among many unexplained post-acute infection syndromes associated with a long list of viral pathogens, including Ebola, the prior SARS viruses, Epstein-Barr virus, and Dengue, as well as non-viral pathogens such as Coxiella burnetii (Q fever syndrome) and Borrelia (post-treatment Lyme disease syndrome).
Iwasaki cited a recent Nature Medicine review article that she co-authored on this topic with an ME/CFS patient, noting: “We really need to understand why some people are failing to recover from these types of diseases.” Emerging evidence supports four different hypotheses regarding pathogenesis:
- viral reservoir/viral pathogen-associated molecular pattern molecules
- autoimmunity
- dysbiosis/viral reactivation
- tissue damage
“Right now, it's too early to exclude or make any conclusions about these. We need to have an open mind to dissect these various possibilities,” she said.