Chronic Multisymptom Illnesses
Chronic multisymptom illness is an umbrella term describing the spectrum of widespread regional and organ-specific symptoms and syndromes that frequently coexist in individuals. In other words, if a patient complains of chronic widespread pain or is diagnosed with fibromyalgia, he or she is likely experiencing fatigue, headaches, depression or some combination of additional symptoms.
CMI defined
In 1998, the Centers for Disease Control and Prevention published a study exploring nonspecific symptoms experienced by Air Force veterans during deployment or following their return from the Gulf War. Researchers surveyed nearly 4,000 veterans who complained of a similar constellation of symptoms, but turned up no laboratory findings or physical abnormalities. As such, they developed a new term - Chronic Multisymptom Illness - to describe this “mystery” illness and came up with the following criteria:
- Presence of one or more chronic symptoms lasting for more than 6 months
- Symptoms must fall into at least two of the following categories: fatigue; mood and cognition (feeling depressed, difficulty remembering or concentrating, feeling moody, feeling anxious, trouble finding words, difficulty sleeping); and musculoskeletal ( joint pain, joint stiffness or muscle pain).
(Fukuda, K., et al. Chronic multisymptom illness affecting Air Force veterans of the Gulf War. JAMA. 1998 Sep 16;280(11):981-8.)
CMI is a term used to classify groups of people with this collection of symptoms and syndromes for research purposes or in literary descriptions of these illnesses. Typically, people are diagnosed with one or more of the syndromes that fall under the umbrella of CMI (fibromyalgia, chronic fatigue syndrome, TMJD, etc.) as opposed to being diagnosed with “CMI.”
The challenge of diagnosis
The challenge for patients and health care providers is to determine whether the symptoms a patient is experiencing are due to a disease with identifiable causes and specific treatment (e.g., cancer, infection) or, non-specific or unknown causes.
Studies have shown that approximately 50-60 percent of visits to primary care physicians result in no identifiable cause, even with exhaustive testing. This can be equally frustrating for patients who are looking for answers and doctors who have few treatment options, which is often the case with fibromyalgia, chronic fatigue syndrome, irritable bowel syndrome and all of the illness classified under CMI.
What is this called when people have symptoms with no identifiable cause?
It's just as difficult for doctors to tell patients they don’t know what is wrong with them as it is for patients to hear it. Until a cause can be identified, doctors often describe the illness in terms of the primary symptom and include a medical term before or after that symptom to indicate an unknown cause. For example, if a person has muscle pain with no clear etiology (cause), doctors may say they have “idiopathic” (we don't know the cause) myalgia (muscle pain) or myalgia NOS (not otherwise specified).
In other instances, we just indicate the area of the body an individual has pain, for example:- Headache
- Low back pain
- Chronic pelvic pain
More recently, we have identified a number of constellations of symptoms - which we call "syndromes” - so these conditions may be more easily diagnosed and treated. In the case of CMI, these syndromes overlap and occur together more commonly than by themselves.
The graphic below shows the overlap of different syndromes.
The chart below shows the different symptoms and syndromes that can be included in chronic multi-symptom illnesses.
