It's often difficult to distinguish between fibromyalgia
and chronic fatigue syndrome
. Are they unrelated, siblings or twins? Researchers and specialists are still trying to determine the answer to this question. Some experts believe they are two completely separate illnesses; others think they are two distinct disorders with many similar symptoms; still others feel they are different facets of the same disorder.
To complicate matters, a significant number of people with FM also have CFS and vise versa. In a September 2002 article in Fibromyalgia AWARE
, a publication of the National Fibromyalgia Association
, Charles W. Lapp, MD, CFS/FM expert and researcher, states that "about 70 percent of persons with CFS meet criteria for FM and about 70 percent of persons with FM also meet criteria for CFS."
Central Sensitivity Syndromes: Muhammad B. Yunus, MD, a pioneer FM researcher, believes that there is a large group of illnesses with overlapping features that he calls "Central Sensitivity Syndromes." What they all have in common is a sensitization of the central nervous system. Under this broad CSS category, he lists disorders such as FM, CFS, migraines, irritable bowel syndrome, TMJ, multiple chemical sensitivities, restless legs syndrome, myofascial pain syndrome, and others. All of these illnesses have some symptoms that overlap one another.
FM and CFS Similarities:
Fibromyalgia and chronic fatigue syndrome share many of the same symptoms, such as: muscle and/or joint pain, debilitating fatigue, headaches, memory loss, difficulty with concentration, forgetfulness, depression, numbness and generalized weakness. Other clinical similarities include:
- Reduced blood flow in the cerebral cortex and midbrain
- Suppression of the hypothalamic pituitary axis
- Disturbed Stage 4 sleep
- Reduced levels of growth hormone
- Lower than normal serotonin levels
- Evidence of a genetic component
FM and CFS Differences:
The simplest explanation of the difference between FM and CFS is that with FM, pain is the most predominant symptom, while with CFS, extreme fatigue with
is most predominant.
Additional distinct differences include:
- Substance P (a neurotransmitter that transmits pain signals) is elevated in FM but not CFS.
- RNaseL (a cellular antiviral enzyme) is frequently elevated in CFS but not in FM.
- Often CFS will be triggered by a flu-like or infectious illness, while FM is more often triggered by some kind of trauma to the body (i.e., accident, injury, surgery, etc.).
How Is a Diagnosis Determined?:
Because the two illnesses are so similar, frequently the diagnosis you receive will depend upon the doctor you see. A rheumatologist is more likely to give you a fibromyalgia diagnosis, whereas if you consult an infectious disease specialist, youll be more apt to receive a diagnosis of chronic fatigue syndrome. If your doctor is a general practitioner or a family practice physician, your diagnosis may depend on which illness they are more familiar with.
For the specific diagnostic criteria of each, see:
Lapp, Charles. Chronic Fatigue Syndrome vs. Fibromyalgia. Fibromyalgia AWARE. September-December 2002: 72-73.
Yunus, Muhammad. Central Sensitivity Syndromes: The Concept for Unifying. Fibromyalgia AWARE. May-August 2002: 41-45.