Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) – An Update

Chronic fatigue syndrome (CFS), also termed myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is an illness that has attracted a good deal of attention lately, mainly because of a proposed relationship with COVID-19.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) - An Update

A couple of years ago, I wrote a blog post addressing 19 important causes of fatigue (1). ME/CFS was on the top of that list, not because it is widespread, but rather because of its ability to strike down where it is least expected. Those affected are typically highly functioning and healthy individuals.

ME/CFS has also been named systemic exertion intolerance disease (SEID) to reflect the condition’s hallmark, which is post-exertional malaise. Post-exertional malaise describes a massive energy crash after relatively minor exertion.

Although certain features are common to nearly all affected patients, ME/CFS is a complex illness. It is a heterogeneous disorder, meaning that symptoms vary a lot between individuals, and so does the underlying cause, which is often clouded in mystery.

Patients often have a history of an antecedent infection that precipitated the prolonged state of fatigue following the initial illness.

The presence of long-term symptoms in some individuals with COVID-19 illness has opened up a new line of research into the mechanisms underlying ME/CFS.

What Is ME/CFS?

The term chronic fatigue syndrome (CFS) was first introduced in the 1980s. The term was chosen after research failed to identify a clear viral association with what was previously called chronic Epstein–Barr virus syndrome (2).

Several biological abnormalities are present in patients with ME/CFS. It is not, as many clinicians believe, a psychological problem, although psychiatric symptoms occur in some patients (3).

For example, there is evidence of various neurologic and immunological abnormalities in patients with ME/CFS (2).

There is no diagnostic test for ME/CFS. Hence, the diagnosis is based on clinical criteria that mainly take into account the symptoms experienced by the patient.

Multiple definitions have been proposed for ME/CFS, and these have changed over time.

One of the key diagnostic criteria is that symptoms should be present for at least six months. Furthermore, symptoms should be of moderate or severe intensity at least half of the time (4).

What Are the Symptoms of ME/CFS?

Overwhelming fatigue is a crucial symptom in patients with ME/CFS. Of note is that the fatigue is very different from just being tired and is not relieved by sleep or rest.

The onset of symptoms may be sudden and is often associated with a typical infection, such as an upper respiratory tract infection.

The symptoms are characteristically exacerbated by excessive physical activity (post-exertional malaise).

Interestingly, affected patients are typically highly functioning individuals who are “struck down” with this illness.

Many patients appear outwardly healthy, sometimes causing relatives or friends to accuse them of malingering (4).

Symptoms of ME/CFS may come and go over time and often fluctuate in severity.

Primary Symptoms

Generally, three primary, or core symptoms, are required for the diagnosis of ME/CFS.

Notably, the fatigue associated with ME/CFS is not a result of unusually difficult activity and is not relieved by rest.

One of the key criteria for diagnosis is a greatly lowered ability to do activities that were usual before the illness (5).

Patients often describe what they call a “crash,” “relapse,” or “collapse,” following a relatively minor physical or mental exertion. This is called post-exertional malaise and is a hallmark of the disorder.

Post-exertional malaise usually occurs after an activity that would not have caused a problem before the illness. It may occur after shopping at the grocery store, taking a shower, or just when trying to keep up with other daily activities. Other potential triggers are emotional distress, physical trauma, and decreased sleep quantity/quality (6).

Sometimes, it may take days, weeks, or longer to recover from a crash.

Patients with ME/CFS often have sleep problems.  Falling asleep and staying asleep may be difficult, and the patient may not feel better or less tired, even after a full night of sleep.

Cognitive problems are often present. These include having trouble thinking quickly, remembering things, and paying attention to details. Patients may feel that they are not able to think clearly, often using the term “brain fog” to describe their feeling.

Patients with ME/CFS may be lightheaded, dizzy, weak, or faint while standing or sitting up. This phenomenon is called orthostatic intolerance and describes different types of discomfort upon assuming the standing position (7).

Other Common Symptoms

Several other symptoms, not classified as primary symptoms, may be present in patients with ME/CFS.

For example, muscle and joint pain are common, and so is headache.

Other symptoms include muscle weakness, shortness of breath, irregular heartbeat, tender lymph nodes in the neck and armpits, a sore throat, digestive problems, and night sweats (5).

How Common Is ME/CFS?

It is estimated that between 836.000 and 2.5 million individuals are affected by ME/CFS in the United States (8).

However, while fatigue is a prevalent complaint in primary care practice, it is believed that only a minority of these cases are due to ME/CFS. In other words, a tiny subset of patients who complain of chronic fatigue has ME/CFS (9).

Even among patients with fatigue of more than six months, the prevalence of ME/CFS seems to be well under ten percent (10).

In one study, the estimated prevalence of ME/CFS ranged from 75 to 267 cases per 100,000 persons. In contrast, the prevalence of chronic fatigue alone was strikingly higher, ranging from 1775 to 6321 cases per 100,000 persons (10).

Studies indicate that ME/CFS is three to four times more common in women than in men. It is most common in persons aged 40–50 years, but the age range is broad and includes children and adolescents (11).

What Is the Cause of ME/CFS?

The cause or causes of ME/CFS is unknown and appears to vary between patients. Both genetic and environmental factors may play a role.

Many patients report an acute onset of symptoms after a flu-like illness that does not go away, and some patients have a history of frequent infections before their illness (12). This suggests that infection can trigger the illness. However, no infectious agent has been proven to cause the disorder.

A syndrome with similarities to ME/CFS occurs in approximately 10% of patients with various infectious agents, such as Epstein-Barr Virus, Ross River Virus, Coxiella burnetti (Q fever), or Giardia (13).

Numerous other viruses have been implicated. These include human herpesvirus type 6 (HHV-6), enteroviruses, Ross river virus, and Borna disease virus. A syndrome similar to ME/CFS has been reported following classical Lyme disease that has been promptly treated (4).

It has been proposed that abnormal immune responses may be at play. One hypothesis is that activation of the immune system in the brain leads to production of cytokines that may be responsible for the symptoms (14).

Several metabolic abnormalities have been described, but their role is unclear. Among those are decreased levels of cortisol, increased levels of insulin-like growth factor, and abnormalities in serotonin activity in the brain (4).

Traumatic events in childhood and stress or emotional instability at any period in life may be associated with the development of ME/CFS.

What Is the Connection With Fibromyalgia?

Fibromyalgia is a chronic pain syndrome characterized by widespread pain, stiffness, and fatigue (1). The cause of the syndrome is unknown, and the pathophysiology is uncertain.

Cognitive complaints, known as fibrofog, are also commonly present (15).

Hence, patients with ME/CFS and fibromyalgia often have similar symptoms. Indeed, research has found that there is a thin line between fibromyalgia and ME/CFS.

The main difference may be that in fibromyalgia, fatigue often takes a backseat to debilitating muscle pain. Also, the association with different infectious agents is much more prominent among patients with ME/CFS than in patients with fibromyalgia.

ME/CFS What Is the Relationship With COVID-19?
ME/CFS is receiving more attention from the medical community than ever before due to the similarities with the long-term effects of COVID-19.

What Is the Relationship With COVID-19?

The short-term symptoms of COVID-19 include fever, cough, shortness of breath, anosmia (loss of smell), dysgeusia (altered sense of taste), fatigue, diarrhea, and other flu-like symptoms. Fortunately, most patients recover from these symptoms and can return to normal life activities.

However, an Italian study published last July suggested that a large portion of patients hospitalized for COVID-19 struggled with persistent symptoms for months after the initial recovery. The most common long-term complaints were fatigue and dyspnea (16).

Since then, prolonged fatigue and brain fog have been reported in many COVID-19 patients. Feeling weak and unusually tired after everyday tasks seems to be a common setback for many COVID-19 patients (17).

A recent British Medical Association press release warned that the effects of “long COVID” would be profound. Almost a third of 4.000 British doctors surveyed had seen or treated patients with symptoms they believed were a longer-term effect of COVID-19 within the first two weeks of August (19).

In many respects, the long-term symptoms of COVID-19 appear similar to those of ME/CFS.

Recently, Anthony Fauci, MD, director of the U.S. National Institute of Allergy and Infectious Diseases, talked about the potential long-term effects of COVID-19. Fauci said that many COVID-19 patients report health issues that are “highly suggestive” of ME/CFS. “If you look anecdotally, there is no question that there are a considerable number of individuals who have a post-viral syndrome that . . . can incapacitate them for weeks and weeks following so-called recovery and clearing of the virus,” Fauci said (20).

One of the key criteria used to diagnose ME/CFS is that symptoms should be present for at least six months. Hence, it remains to be seen how many people with COVID-19 will go on to develop this illness according to its current definition.

What is certain, however, is that ME/CFS is receiving more attention from the medical community than ever before due to the similarities with the long-term effects of COVID-19.

How Is ME/CFS Treated?

At present, there are no treatments that have been proven effective for patients ME/CFS. Although many therapies have been tried, none are curative.

Due to the heterogeneity of the disorder, treatment has to be individualized, addressing the most disruptive symptoms first (21).

Management should be supportive and focus on treating common symptoms such as sleep disorders, pain, depression and anxiety, memory and concentration difficulties, dizziness and lightheadedness.

Physical Activity

Remaining physically active is vital for patients with ME/CFS. However, the approach must be individualized, since exercise can exacerbate post-exertional malaise.

Post-exertional malaise can be addressed by activity managementalso called pacing. The goal of pacing is to learn to balance rest and activity to avoid flare-ups (22).

To do this, patients need to find their individual limits for mental and physical activity. The aim is to keep their activity within these limits. This is sometimes referred to as staying within the “energy envelope.

Sleep

Paying attention to sleep hygiene is very important for people with ME/CFS.

Strong sleep hygiene means having both a bedroom environment and daily routines that promote consistent, uninterrupted sleep (23).

Sleep should be made a priority. Skipping sleep in order to work, study, socialize, or exercise is not recommended.

Having the same bedtime each night is essential, and so is fixed wake-up time.

Sleep medication should be used carefully.

Pain

Patients with ME/CFS often have pain in their muscles and joints, and headaches are common.

Physiotherapy, stretching, massage, heat, and toning exercises may all be helpful.

Non-steroidal anti-inflammatory drugs (NSAIDs), like acetaminophen, paracetamol, and ibuprofen, are often used to treat pain. If these do not provide enough pain relief, patients may need to see a pain specialist.

Depression and Anxiety

Depression and anxiety may affect the quality of life in some patients with ME/CFS.

Psychotherapy and/or drug therapy may provide benefit for these patients.

Some people with ME/CFS might benefit from trying techniques like deep breathing and muscle relaxation, massage, and movement therapies (such as stretching, yoga, and tai chi) (22).

The Take Home Message

ME/CFS often affects highly functioning and healthy individuals.

There is no diagnostic test for ME/CFS. Hence, the diagnosis is based on clinical criteria that mainly take into account the symptoms experienced by the patient.

Overwhelming fatigue, post-exertional malaise, sleep problems, cognitive difficulties, pain, and orthostatic intolerance are key symptoms

One of the key diagnostic criteria is that symptoms should be present for at least six months.

Prolonged fatigue and brain fog have been reported in many COVID-19 patients. Many of these symptoms are remindful of those associated with ME/CFS.

It remains to be seen how many people with COVID-19 will go on to develop ME/CFS according to its current definition.

At present, there are no treatments that have been proven effective for patients ME/CFS.

Management should be supportive and focus on treating common symptoms such as sleep disorders, pain, depression and anxiety, memory and concentration difficulties, dizziness and lightheadedness.




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