Premise: this post will be quite long, but the theme is of primary importance for the sufferers; so I apologize in advance for in this case it won’t be an ‘atom block’, but I will keep it a block referring to the topic.
A diagnostic criteria is a tool used in medicine to identify the sufferers of a given disease in order to administer them the right therapy and assistance and also to select a proper group of patients for medical investigations on that disease.
To underline the importance of a good d.c. let me tell you a story.
Let’s imagine that I give my collaborators the instruction to bring me some animals with the following characteristics:
-with four paws,
-between 50 gr. and 100 gr. in weight,
-have a stretched body and a tail,
most of them will bring me lizards.
While if I asked for:
-with four paws,
-between 50 gr. and 100 gr. in weight,
-have roundish body and no tail,
most of them will bring me little frogs.
And we are talking about quite different animals: lizards are reptiles and frogs are amphibians, they neither belong to the same class. And if I didn’t specify the form, I would be surrounded by lizards, frogs and who knows how many other animals!
Namely, the characteristics used to make a selection considerably affect the results of the same: changing just one of them you may obtain one selection or a completely different one.
Moving the conversation to medicine, we understand how patients identification (for therapeutic purpose) and selection (for investigative purpose) will have direct consequences on the type of therapy and on the its results on one side, and on scientific research on the other side.
If, for example, I identify cancer sufferers and I try on them therapies as chemotherapy and surgical removal of metastases, the number of recoveries will tell me that I have chosen well the therapy, on the base of that criteria. While if the d.c. is not good and I think I am curing cancer patients but they really are depression patients, chemotherapy will be dangerous for them.
From the point of view of the medical investigation is also clear that the results of a medical trial will be totally altered if the group of patient is not well selected.
Thus making a study on a disease is not sufficient, it’s essential to know how that patients have been selected.
So, when a ME sufferer goes to a specialist to find out what is happening to him/her, that specialist needs to know the right diagnostic criteria, that is the following, from ME 2011 ICC, page 3:
Diagnostic Criteria for ME:
Myalgic encephalomyelitis is an acquired neurological disease with complex global dysfunctions. Pathological dysregulation of
the nervous, immune and endocrine systems,with impaired cellular energy metabolism and ion transport are prominent features.
Although signs and symptoms are dynamically interactive and causally connected, the criteria are grouped by regions of pathophysiology to provide general focus.
A patient will meet the criteria for postexertional neuroimmune exhaustion (A), at least one symptom from three neurological
impairment categories (B), at least one symptom from three immune ⁄ gastro-intestinal ⁄ genitourinary impairment categories
(C), and at least one symptom from energy metabolism⁄ transport impairments (D).
A.Postexertional neuroimmune exhaustion (PENEpen’-e):Compulsory
This cardinal feature is a pathological inability to produce sufficient energy on demand with prominent symptoms primarily in the neuroimmune regions. Characteristics areas follows:
1. Marked, rapid physical and ⁄ or cognitive fatigability in response to exertion,which may be minimal such as activities
of daily living or simple mental tasks, can be debilitating and cause a relapse.
2. Postexertional symptom exacerbation: e.g. acute flu-like symptoms,pain and worsening of other symptoms.
3. Postexertional exhaustion may occur immediately after activity or be delayed by hours or days.
4. Recovery period is prolonged, usually taking 24 h or longer. A relapse can last days, weeks or longer.
5. Low threshold of physical and mental fatigability (lack of stamina) results in a substantial reduction in pre-illness
Operational notes: For a diagnosis of ME, symptom severity must result in a significant reduction of a patient’s premorbid
activity level. Mild (an approximate 50% reduction in pre-illness activity level), moderate (mostly housebound), severe (mostly
bedridden) or very severe (totally bedridden and need help with basic functions). There may be marked fluctuation of symptom
severity and hierarchy from day to day or hour to hour. Consider activity, context and interactive effects. Recovery time: e.g.
Regardless of a patient’s recovery time from reading for ½ hour, it will take much longer to recover from grocery shopping for ½ hour and even longer if repeated the next day – if able. Those who rest before an activity or have adjusted their activity level to their limited energy may have shorter recovery periods than those who do not pace their activities adequately. Impact: e.g. An
outstanding athlete could have a 50% reduction in his ⁄ her pre-illness activity level and is still more active than a sedentary person.
At least one symptom from three of the following four symptom categories:
a. Difficulty processing information: slowed thought, impaired concentration e.g. confusion, disorientation, cognitive overload,difficulty with making decisions, slow ed speech, acquired or exertional dyslexia
b. Short-term memory loss: e.g. difficulty remembering what one wanted to say,what one was saying, retrieving words, recalling information, poor working memory
a. Headaches: e.g. chronic, generalized headaches often involve aching of the eyes, behind the eyes or back of the head that
may be associated with cervical muscle tension;migraine; tension headaches
b. Significant pain can be experienced in muscles, muscle-tendon junctions, joints, abdomen or chest. It is non inflammatory
in nature and often migrates. e.g. generalized hyperalgesia, widespread pain (may meet fibromyalgia criteria), myofascialor
3. Sleep disturbance
a. Disturbed sleep patterns: e.g. insomnia, prolonged sleep including naps, sleeping most of the day and being awake most
of the night, frequent awakenings, awaking much earlier than before illness onset, vivid dreams ⁄ nightmares
b. Unrefreshed sleep: e.g. awaken feeling exhausted regardless of duration of sleep,day-time sleepiness
4. Neurosensory, perceptual and motor disturbances
a. Neurosensory and perceptual: e.g. inability to focus vision, sensitivity to light, noise, vibration, odor, taste and touch;
impaired depth perception
b. Motor: e.g. muscle weakness, twitching,poor coordination, feeling unsteady on feet, ataxia
Notes: Neurocognitive impairments, reported or observed, become more pronounced with fatigue. Overload phenomena may be evident when two tasks are performed simultaneously. Abnormal accommodation responses of the pupils are common.
Sleep disturbances are typically expressed by prolonged sleep, sometimes extreme, in the acute phase and often evolve into
marked sleep reversal in the chronic stage. Motor disturbances may not be evident in mild or moderate cases but abnormal tandem gait and positive Romberg test may be observed
in severe cases.
C. Immune, gastro-intestinal and genito urinary Impairments
At least one symptom from three of the following five symptom categories:
1. Flu-like symptoms may be recurrent or chronic and typically activate or worsen with exertion. e.g. sore throat, sinusitis,
cervical and ⁄ or axillary lymphnodes may enlarge or be tender on palpitation
2. Susceptibility to viral infections with prolonged recovery periods
3. Gastro-intestinal tract: e.g.nausea, abdominal pain, bloating, irritable bowel syndrome
4. Genitourinary: e.g. urinary urgency or frequency, nocturia
5. Sensitivities to food, medications,odors or chemicals
Notes: Sore throat, tender lymph nodes, and flu-like symptoms obviously are not specific to ME but their activation in reaction to
exertion is abnormal.The throat may feel sore, dry and scratchy. Facial injection and crimson crescents may be seen in the tonsillar fossae, which are an indication of immune activation.
D. Energy production⁄ transportation impairments: At least one symptom:
1. Cardiovascular: e.g. inability to tolerate an upright position – orthostatic intolerance, neurally mediated hypotension, postural orthostatic tachycardia syndrome, palpitations with or without cardiac arrhythmias, light-headedness ⁄ dizziness
2. Respiratory: e.g. air hunger, laboured breathing, fatigue of chest wall muscles
3. Loss of thermostatic stability: e.g. subnormal body temperature,marked diurnal fluctuations; sweating episodes, recurrent feelings of feverishness with or without low grade fever, cold extremities
4. Intolerance of extremes of temperature
Notes: Orthostatic intolerance may be delayed by several minutes. Patients who have orthostatic intolerance may exhibit mottling of extremities, extreme pallor or Raynaud’s Phenomenon. In the chronic phase, moons of finger nails may recede.
Symptoms may progress more slowly in children than in teenagers or adults. In addition to postexertional neuroimmune exhaustion, the most prominent symptoms tend to be neurological: headaches, cognitive impairments,and sleep disturbances.
1. Headaches:Severe or chronic headaches are often debilitating. Migraine may be accompanied by a rapid drop in temperature,
shaking, vomiting, diarrhea and severe weakness.
2. Neurocognitive impairments: Difficulty focusing eyes and reading are common. Children may become dyslexic, which
may only be evident when fatigued. Slow processing of information makes it difficult to follow auditory instructions or take
notes. All cognitive impairments worsen with physical or mental exertion. Young people will not be able to maintain a full
3. Pain may seem erratic and migrate quickly. Joint hypermobility is common.
Notes: Fluctuation and severity hierarchy of numerous prominent symptoms tend to vary more rapidly and dramatically than in
———Atypicalmyalgic encephalomyelitis: meets criteria for postexertional neuroimmune exhaustion but has a limit of two
less than required of the remaining criterial symptoms. Pain or sleep disturbance may be absent in rare cases.
Exclusions:As in all diagnoses, exclusion of alternate explanatory diagnoses is achieved by the patient’s history, physical examination, and laboratory ⁄ biomarker testing as indicated. It is possible to have more than one disease but it is important that each one is identified and treated. Primary psychiatric disorders, somatoform disorder and substance abuse are excluded. Pediatric:
‘primary’ school phobia.
Comorbid entities: Fibromyalgia, myofascial pain syndrome, temporo mandibular joint syndrome, irritable bowel syndrome,
interstitial cystitis, Raynaud’s phenomenon, prolapsed mitral valve, migraines, allergies, multiple chemical sensitivities, Hashimoto’s thyroiditis, Sicca syndrome, reactive depression. Migraine and irritable bowel syndrome mayp recede ME but then become associated with it. Fibromyalgia overlaps.
Observe that ME patients must present a large list of proven symptoms belonging to many different areas; this is way we can say that this diagnostic criteria is a very tight filter.
There are some updatings in 2011 criteria respect to 2003 criteria.
The first one consists in the disappearance of the point 7 of 2003 criteria:
“7. The illness persists for at least six months.”
In the 2011 ICC, at page 2, we read:
“The Canadian Consensus Criteria were used as a starting point, but significant changes were made. The 6-month waiting period before diagnosis is no longer required. No other disease criteria require that diagnoses be withheld until after the patient has suffered with the affliction for 6 months. Notwithstanding periods of clinical investigation will vary and may be prolonged, diagnosis should be made when the clinician is satisfied that the patient has ME rather than having the diagnosis restricted by a specified time factor. Early diagnoses may elicit new insights into the early stages of pathogenesis; prompt treatment may lessen the severity and impact.”
Another update is on fatigue, point 1 and 2 of 2003 criteria disappear and in their place we find a detailed description of ‘Postexertional neuroimmune exhaustion (PENE pen¢-e)’.
Let me postpone the ‘fatigue’ theme in a dedicated post.
Now some doubts may arise above all in patients who haven’t received a diagnosis yet.
Is this criteria objective?
To the extent that each manifestation is objectively diagnosed, the ME criteria is objective.
For example, abnormal tandem gait and positive Romberg test indicate motor disturbances, that are neurological manifestations. Or, irritable bowel syndrome or bowel’s inflammation are easily detectable by a simple gastroenterological visit and a colonoscopy. And so on.
The real difficulty of this diagnostic criteria lies in its complexity: a clinician should be quite trained to give you a written document saying that you have ME.
Also, there’s the need to find a scale for each symptom, as pointed at page 8:
“..the panel is developing an International Consensus Symptom Scale (ICSS) that will build on these underlying interactions. However, a necessary first step in establishing a quantitative score for any diagnostic instrument is the specification of measurable factors that are most relevant to the illness. Establishing such criteria was the primary objective of this work, and we believe the International Consensus Criteria will help clarify the unique signature of ME.”
Another doubt: do specific biological tests that directly identify ME patients exist? Wouldn’t it be simpler to make a blood test or a urine test that tells me if I have ME or not?
A test with this feature would be a test that finds biological markers.
At the moment this theme is controversial. I will talk about biological markers in a dedicated post.
What doesn’t mean that ME is not an organic illness, because organic evidences have been found in all pathological areas that ME involves. For example, about PENE we read, at pages 5-6:
“Numerous papers document abnormal biological responses to exertion, such as loss of the invigorating effects of exercise , decreased pain threshold [47–49], decreased cerebral oxygen and blood volume ⁄ flow [50–53], decreased maximum heart rate , impaired oxygen delivery to muscles , elevated levels of nitric oxide metabolites  and worsening of other symptoms . Patients reach the anaerobic threshold and maximal exercise at a much lower oxygen consumption level . Reported prolonged effects of exertion include elevated sensory signaling to the brain  that is interpreted as pain and fatigue , elevated cytokine activity , delay in symptom activation  and a recovery period of at least 48 h . When an exercise test was given on two consecutive days, some patients experienced up to a 50%drop in their ability to produce energy on the second evaluation . Both submaximal and self-paced physiologically limited exercise resulted in postexertional malaise .”
I see a big lack in this document: the distinctive and important in ME patients is that exertions accelerate the degenerative process in all body systems, at every physical or mental overload or overstress sufferers’ body loose health, get sick more and more, in a progressive way; sustained overexertion causes serious and permanent bodily damage, even unto death.
And it is also missed the description of “exertion”, that for a ME patient can also be the action of breathing, or eating or listening..
I will explain the biochemical reason of this later on.
A shorter and simpler, as well as more complete and more specific screening protocol is needed.
“These guidelines are designed specifically for use by the primary care physician in the hope of improving rapid diagnosis and treatment by first-line medical care providers. This may result in the development of an additional short-form version that would build on the relationships linking symptoms to formulate an abbreviated screening protocol.”
We stay awaiting for it.
But the story doesn’t finish here because…
A diagnosis of ME was already possible much before the ICC criteria of 2011..
I invite you to read this other post, that I called “Diagnosis by tests, The Nightingale Definition of ME by Dr. Hyde” (quite large title.. ):