Comorbidities of Myalgic Encephalomyelitis

A comorbidity is a diagnosis that commonly occurs independently of, and at the same time as another condition. For example, Hashimoto's thyroiditis is a comorbidity of ME/CFS because they are independent conditions, but postural orthostatic tachychardia syndrome is a symptom used to aid the diagnosis of ME/CFS is not a comorbidity even though both are distinct disorders and both frequently occur together. Symptoms of ME/CFS that are not a separate diagnosis are not counted as comorbidities.

Patients with myalgic encephalomyelitis frequently meet the criteria for one or more other conditions including: postural orthostatic tachychardia syndrome and other forms of orthostatic intolerance; mast cell activation syndrome; Ehlers-Danlos syndrome;  fibromyalgia;  endometriosis; and a variety of autoimmune diseases. It is not yet known whether these are true co-morbidities that share underlying genetic or environment risk factors, or if they are artifacts of diagnosis and disease definition.

Canadian Consensus Criteria
The Canadian Consensus Criteria recognizes the following comorbidities for ME/CFS: fibromyalgia, myofascial pain syndrome (MPS), temporomandibular joint syndrome (TMJ), irritable bowel syndrome (IBS), interstitial cystitis, irritable bladder syndrome, Raynaud's phenomenon, prolapsed mitral valve, depression, migraine, allergies, multiple chemical sensitivities (MCS), Hashimoto's thyroiditis, and sicca syndrome (Sjögren's syndrome).

Preceding conditions
Conditions that begin many years before ME/CFS but then become associated with it, such as irritable bowel syndrome, migraines and depression, are regarded as more loosely associated. ME/CFS and fibromyalgia are regarded by the Canadian Consensus Criteria as often closely connected overlapping syndromes.

International Consensus Criteria
The primer for the International Consensus Criteria for myalgic encephalomyelitis, which is based on the earlier Canadian Consensus Criteria gives the following comorbidities: myofascial pain syndrome, temporomandibular joint syndrome (TMJ), interstitial cystitis, Raynaud's phenomenon, prolapsed mitral valve, irritable bladder syndrome, Hashimoto's thyroiditis, sicca syndrome (Sjögren's syndrome), secondary depression, allergies, and multiple chemical sensitivities. Fibromyalgia (FMS) is considered "an overlap condition."

Preceding conditions
Irritable bowel syndrome and migraine "may precede ME and then become associated with it."

Theories
RCCX Theory

Clinical perspectives

 * In “The Nightingale Research Foundation Definition of Myalgic Encephalomyelitis (M.E.),” ME physician Byron Hyde has describes the relationship between ME, POTS/dyaustonomia, and EDS in terms of disease severity:
 * “Patients with dysautonomia and/or POTS dysfunctions invariably demonstrated hypoperfusion in the operculum area overlying the insular cortex as in the above patient, suggesting an insular cortex injury in our dysautonomia patients.”
 * “Patients with pre-existing or newly-discovered (a) Ehlers-Danlos Hypermobility Syndrome, (b) Collagen diseases... are among the most disabled patients we have seen.”
 * A case series by Peter Rowe of adolescents referred to his clinic found 12 patients who also met the criteria for Ehlers-Danlos Syndrome and had orthostatic intolerance (postural orthostatic tachycardia or neurally-mediated hypotension). He concluded that “Among patients with CFS and orthostatic intolerance, a subset also has EDS.”
 * At a two-day physician summit in Salt Lake City, Utah March 2018, physicians discussed the relationship between “Chronic Fatigue Syndrome” and mast cell activation syndrome.
 * David Kaufman: "ME/CFS is a descriptive diagnosis of a bunch of symptoms, but it says nothing about what's causing the symptoms, which is probably part of the reason it's so hard for it to get recognition. So, the question becomes, What other pathology is driving this illness and making the person feel so ill? I think mast cell activation is one of those drivers, whether cause, effect, or perpetuator, I don't know."
 * Charles Lapp: "I see a lot of this. I think it's one of the many overlap syndromes that we've been missing for years."
 * Susan Levine: "I suspect 50% to 60% of ME/CFS patients have it. It's a very new concept."...In Levine's experience, MCAS often manifests in patients being unable to tolerate certain foods or medications. "If we can reduce the mast cell problem, we can facilitate taking other drugs to treat ME/CFS," she said. However, she also cautioned, "It's going to be a subset, not all ME/CFS patients."

Studies and collaborations

 * A lab at the Stanford Genome Technology Center is currently studying the genetic relationship between EDS and ME/CFS. Early data show a possible relationship.

Research findings
Recent research has focused on the possible relationships between EDS, POTS, and MCAS. In particular, these disorders were associated in a sample of 25 families.

Diagnoses that are symptoms of ME/CFS
A number of illnesses and diseases are not regarded as true comorbidities, but are so common that they classed as diagnostic signs and symptoms instead:

Symptoms that are also a diagnosis include: category = Diagnoses category = Signs and symptoms mode = unordered ordermethod=sortkey order=ascending