FM/CFS/ME RESOURCES - The Difference Between CFS and ME


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The Difference Between CFS and ME

Myalgic encephalomyelitis (ME) is a multi-system disease adversely affecting the cellular mitochondria and the heart, brain, neuroendocrine, immune, and circulatory systems. ME was first described in the 1950's following the recognition of many cases around the world, including a number of cases at the Royal Free Hospital in England. Many different viruses, bacteria, or toxins in combination with genetic factors may be involved in the etiology of the disease, which usually begins in childhood or early adulthood with an acute infection.

Сhronic fatigue syndrome (CFS) is the most common name given to a variably debilitating disorder or disorders generally defined by persistent fatigue unrelated to exertion, not substantially relieved by rest and accompanied by the presence of other specific symptoms for a minimum of six months.

The U.S. Centers for Disease Control and Prevention (CDC) first defined CFS in 1988. This definition was later rolled over to a more complex 1994 definition, which was subsequently corrected and corrected again. These CFS definitions have multiplied beyond the two CDC definitions and now include the Oxford Dictionary definitions of CFS (there are two of them), the Australian definitions, and the more recent Canadian definition that talks of ME/CFS as though they were the same illness. They are not. ME has a clearly defined disease process while CFS by definition has always been a syndrome.

Diagnostic Criteria For CFS

Your clinician should consider a diagnosis of CFS if these two criteria are met:

  1. Unexplained, persistent fatigue that's not due to ongoing exertion, isn't substantially relieved by rest, is of new onset (not lifelong) and results in a significant reduction in previous levels of activity.
  2. Four or more of the following symptoms are present for six months or more:
    • Impaired memory or concentration
    • Postexertional malaise (extreme, prolonged exhaustion and sickness following physical or mental activity)
    • Un refreshing sleep
    • Muscle pain
    • Multi joint pain without swelling or redness
    • Headaches of a new type or severity
    • Sore throat that's frequent or recurring
    • Tender cervical or axillary lymph nodes

    In addition, a number of minor symptoms may also appear:

    • Poor sleep
    • Achiness
    • Brain fog
    • Increased thirst
    • Bowel disorders
    • Recurrent infections
    • Exhaustion after minimal exertion

Chronic fatigue syndrome can resemble many other illnesses, including mononucleosis, chronic lyme disease, lupus, multiple sclerosis, Fibromyalgia, primary sleep disorders, severe obesity and major depressive disorders. Medications can also cause side effects that mimic the symptoms of CFS/ME.

Because CFS can resemble many other disorders, it's important not to self-diagnose CFS. It's not uncommon for people to mistakenly assume they have chronic fatigue syndrome when they have another illness that needs to be treated. A CFS diagnosis can be made only after other conditions have been excluded.

The 'London' Criteria for ME - Version 2

These three criteria must all be present for a diagnosis of M.E./PVFS to be made. If any of these are not present the volunteer research subject should not be used for the purpose of research into M.E./PVFS and an alternative diagnosis should be keenly sought.

    A) Exercise-induced fatigue precipitated by trivially small exertion, physical or mental, relative to the patient's previous exercise tolerance.

    B) Impairment of short-term memory and loss of powers of concentration, usually coupled with other neurological and psychological disturbances such as emotional lability, nominal dysphasia, disturbed sleep patterns, dysequilibrium or tinnitus.

    C) Fluctuation of symptoms, usually precipitated by either physical or mental exercise (see b) above.

These symptoms should have been present for at least 6 months and should be ongoing.

The Nightingale Definition of ME

Primary ME is a chronic disabling, acute onset biphasic epidemic or endemic (biphasic) infectious disease process affecting both children and adults. There are both central and peripheral aspects to this illness.

    A) The Central Nervous System (CNS) symptoms, as well as the clinical and technological abnormalities, are caused by a diffuse and measurable injury to the vascular system of the Central Nervous System. These changes in the organization of the CNS are caused by a combined infectious and immunological injury and their resulting effect on CNS metabolism and control mechanisms. Much of the variability observed in an ME patient's illness is due to the degree and extent of the CNS injury and the ability of the patient to recover from these injuries.

    B) A significant number of the initial and long-term peripheral or body symptoms, as well as clinical and technological body abnormalities in the ME patient, are caused by variable changes in the peripheral and CNS vascular system. The vascular system is perhaps the largest of the body's organs and both its normal and patho physiological functions are in direct relationship to CNS and peripheral vascular health or injury, to CNS control mechanisms and to the difficulty of the peripheral vascular system and organs to respond to CNS neuro-endocrine and other chemical and neurological stimuli in a predictable homeostatic fashion.

    C) When pain syndromes associated with ME occur, they are due to a combined injury of (i) the posterior spinal cord and / or posterior root ganglia and appendages, (ii) patho-physiological peripheral vascular changes, and (iii) CNS pain reception homeostasis mechanisms.

The Canadian Clinical Case Definition for ME

1. POST-EXERTIONAL MALAISE AND FATIGUE: There is a loss of physical and mental stamina, rapid muscular and cognitive fatigability, post-exertional fatigue, malaise and/or pain, and a tendency for other symptoms to worsen. A pathologically slow recovery period (it takes more than 24 hours to recover). Symptoms exacerbated by stress of any kind. Patient must have a marked degree of new onset, unexplained, persistent, or recurrent physical and mental fatigue that substantially reduces activity level.

2. SLEEP DISORDER: Unrefreshing sleep or poor sleep quality; rhythm disturbance.

3. PAIN: Arthralgia and/or myalgia without clinical evidence of inflammatory responses of joint swelling or redness. Pain can be experienced in the muscles, joints, or neck and is sometimes migratory in nature. Often, there are significant headaches of new type, pattern, or severity.

4. NEUROLOGICAL/COGNITIVE MANIFESTATIONS: Two or more of the following difficulties should be present: confusion, impairment of concentration and short-term memory consolidation, difficulty with information processing, categorizing, and word retrieval, intermittent dyslexia, perceptual/sensory disturbances, disorientation, and ataxia. There may be overload phenomena: informational, cognitive, and sensory overload - e.g., photophobia and hypersensitivity to noise - and/or emotional overload which may lead to relapses and/or anxiety.


    1. AUTONOMIC MANIFESTATIONS: Orthostatic Intolerance: e.g., neurally mediated hypotension (NMH), postural orthostatic tachycardia syndrome (POTS), delayed postural hypotension, vertigo, light-headedness, extreme pallor, intestinal or bladder disturbances with or without irritable bowel syndrome (IBS) or bladder dysfunction, palpitations with or without cardiac arrhythmia, vasomotor instability, and respiratory irregularities.

    2. NEUROENDOCRINE MANIFESTATIONS: loss of thermostatic stability, heat/cold intolerance, anorexia or abnormal appetite, marked weight change, hypoglycemia, loss of adaptability and tolerance for stress, worsening of symptoms with stress and slow recovery, and emotional lability.

    3. IMMUNE MANIFESTATIONS: tender lymph nodes, sore throat, flu-like symptoms, general malaise, development of new allergies or changes in status of old ones, and hypersensitivity to medications and/or chemicals.

6. The illness persists for at least 6 months. It usually has an acute onset, but onset also may be gradual. Preliminary diagnosis may be possible earlier. The disturbances generally form symptom clusters that are often unique to a particular patient. The manifestations may fluctuate and change over time. Symptoms exacerbate with exertion or stress.

What Are the Symptoms of ME and CFS?

ME Symptoms CFS Symptoms
  • sore throat
  • flu
  • fever
  • chills
  • body aches
  • sweats
  • low body temperature
  • lymphadenopathy (swollen/enlarged lymph nodes)
  • postexertional malaise lasting more than 24 hours (exhaustion and increased symptoms) following physical or mental exercise
  • muscle weakness
  • muscle pain
  • hypoglycemia (low blood sugar)
  • weight change
  • nausea
  • vomiting
  • vertigo (whirling or spinning movement)
  • chest aches
  • chest pain
  • cardiac arrhythmia
    (An arrhythmia is a disorder of the heart rate (pulse) or heart rhythm, such as beating too fast (tachycardia), too slow (bradycardia), or irregularly)
  • resting tachycardia
  • orthostatic tachycardia
    (orthostasis means standing upright, tachycardia is the heart beating too fast)
  • orthostatic fainting or faintness
  • ophthalmoplegia
    (paralysis or weakness of one or more of the muscles that control eye movement)
  • eye pain
  • stroke-like episodes
  • difficulty swallowing
  • paresthesias
    (sensation of tingling, burning, pricking, or numbness of a person's skin)
  • peripheral neuropathic pain
  • polyneuropathy
    (neurological disorder that occurs when many nerves throughout the body malfunction simultaneously)
  • extreme pallor
  • sleep disorder
  • myoclonus (brief, involuntary twitching of a muscle or a group of muscles)
  • hyperreflexia (overactive or overresponsive reflexes)
  • temporal lobe and other types of seizures
  • cognitive, memory and concentration impairment
  • attention deficit
  • anxiety
  • confusion
  • disorientation
  • light/sound sensitivity
  • blurred vision
  • wavy visual field, and other visual and neurological disturbances
  • cognitive dysfunction, including impaired memory or concentration
  • postexertional malaise lasting more than 24 hours (exhaustion and increased symptoms) following physical or mental exercise
  • unrefreshing sleep
  • joint pain (without redness or swelling)
  • persistent muscle pain
  • headaches of a new type or severity
  • tender cervical or axillary lymph nodes
  • sore throat
  • irritable bowel, abdominal pain, nausea, diarrhea or bloating
  • chills and night sweats
  • brain fog
  • chest pain
  • shortness of breath
  • chronic cough
  • visual disturbances
    • blurring
    • sensitivity to light
    • eye pain or dry eyes
  • allergies or sensitivities to:
    • foods
    • alcohol
    • odors
    • chemicals
    • medications
    • noise
  • difficulty maintaining upright position
    • orthostatic instability
    • irregular heartbeat
    • dizziness
    • balance problems or fainting)
  • psychological problems
    • depression
    • irritability
    • mood swings
    • anxiety
    • panic attacks)
  • jaw pain
  • weight loss or gain

Symptoms That Set ME Apart From CFS

Though the symptoms of CFS resemble those of ME, the differences are so significant that they would exclude ME patients from the 1988 and 1994 CDC diagnoses of CFS. The following features of ME separate it from CFS:

  • The epidemic characteristics
  • The known incubation period
  • The acute onset
  • The associated organ pathology, particularly cardiac
  • Infrequent deaths with pathological Central Nervous System changes
  • Neurological signs in the acute and sometimes chronic phases
  • The specific involvement of the autonomic nervous system
  • The frequent subnormal patient temperature
  • The fact that chronic fatigue is not an essential characteristic of the chronic phase of ME

ME Diagnosis Versus CFS

ME experts from the U.K., U.S., Canada, Australia and many other countries who have studied this disease have stated that it's the definitions that determine the diagnosis. The current Consensus Document and most ME definitions require the major criteria of severe muscle fatigue following minimal exertion with prolonged recovery time, and neurological disturbances, especially autonomic, cognitive and sensory functions, and variable involvement of cardiac and other systems, with a prolonged relapsing course. This is a very specific list of criteria, and a major point to note is that the CNS (central nervous system) dysfunction of ME can be measured.

Alternately, CFS definitions present the major criterion of fatigue that lasts 6 months and reduces the level of function by at least 50%. Post-exertional malaise and neurological abnormalities are considered minor and optional criteria. So this broad definition could encompass any of many illnesses in which fatigue plays a role. Fatigue is not only a symptom of numerous illnesses, but it is something experienced by normal, healthy people. And there are no reliable objective ways to measure fatigue.

Dr. Byron Hyde, author of the Nightingale Definition of M.E. states that, "I do not describe a patient as having M.E. unless there is an abnormal SPECT. If the SPECT is normal, I often repeat it along with xenon SPECT. If the brain scans remain normal, I conclude that it is unlikely to be M.E. I then refer to the patient as a CFS patient and search for other causes of the fatigue syndrome."

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