DIFFERENCE BETWEEN FM & CFS/ME

A lot of people - even doctors - want to lump fibromyalgia (FM) and chronic fatigue syndrome (CFS/ME) together, believing they're different manifestations of the same underlying problem.

While it's true that the symptoms are remarkably similar, these conditions aren't the same. The top researchers of both syndromes point to numerous differences that should not be ignored.

Similarities Between FM & CFS/ME

• Pain
• Fatigue
• Sleep disorders
• Irritable bowel syndrome symptoms
• Chronic headaches
• Association with Temporomandibular Joint Syndrome (TMJ)
• Cognitive or memory impairment
• Dizziness
• Impaired coordination

However, those are largely surface similarities. When we talk about pain, most of us (including health-care workers) don't have a good vocabulary for different types of pain. When you look deeper, you discover that FM is linked to pain states such as hyperalgesia (pain amplification) and allodynia (pain from a typically non-painful source). CFS/ME, meanwhile, is associated with muscle aches like what you get with the flu. Also, not everyone with CFS/ME has pain.

We also have woefully poor language for describing fatigue, but here again, research shows that people with CFS/ME have unique fatigue states. The same has not been found about FM, and not everyone with FM has fatigue.

The types of unrefreshing sleep are vastly different, as well. People with CFS/ME may sleep most of the time, yet never feel rested. So far, researchers have been unable to identify any actual sleep disorders in CFS/ME, but they have found abnormal sleep patterns. FM, on the other hand, is generally characterized by one or more recognized sleep disorders as well as abnormal sleep rhythms. In many, the sleep disorders pre-date FM. Generally, those with FM get very little sleep.

When it comes to exercise, which causes symptom flares or "crashes" in both conditions, studies link the reaction to different physiological processes, including low growth hormone in FM and abnormal heart rhythms and lactic acid processing in CFS/ME.

The presence of central sensitization puts these conditions in the same overall category, but it's not unique to these illnesses.

Differences Between FM & CFS/ME

One key difference, when it comes to a diagnosis, is which symptom is worst, pain or fatigue. The diagnosis could also be influenced by whether your doctor is more familiar with the American College of Rheumatology's criteria for FM or the CDC's guidelines for CFS/ME.

However, experts have found some significant differences.

• Greater immune dysfunction in CFS/ME


• Abnormal nerve response in FM


• Stress-system (HPA axis) abnormalities predominantly from the adrenal glands in CFS/ME and the hypothalamus in FM


• FM patients have abnormal levels of a cellular chemical called substance P (which transmits pain signals), this level appears to be normal in CFS/ME patients.


• CFS/ME patients often have high levels of a cellular antiviral enzyme called RNase L, while the level is normal in FM patients.


• CFS/ME diagnostic criteria include low-grade fever and sore throat, FM criteria do not.


• The onset of FM frequently is traced to a physical or emotional trauma. The pain of FM usually gets better with heat and massage, while CFS/ME pain doesn't.


• Elevated pro-inflammatory cytokines in CFS/ME, and sometimes elevated anti-inflammatory cytokines in FM.


• FM has generally not been connected with viral and bacterial infections (with a few exceptions, such as mycoplasma and parvovirus B19)


• CFS/ME has occurred in epidemics, but none have been reported for FM


• FM is not thought to ever be progressive or life-threatening (as CFS/ME can be in rare cases)


• FM does not usually cause severe immune dysfunction, neurological symptoms and exercise intolerance


• CFS/ME usually does not cause allodynia (exaggerated response to pain: non-painful stimuli experienced as painful)


• Diagnosis of FM requires tender points (painful areas in the muscle that occur in certain places)


• CFS/ME tends to begin after flu-like symptoms and may be linked to a virus


• CFS/ME patients often have high levels of a cellular antiviral enzyme called RNase L, while the level is normal in FM patients


• CFS/ME diagnostic criteria include low-grade fever and sore throat, while FM criteria do not


• People with FM have tender points and abnormal levels of a cellular chemical called substance P (which transmits pain signals), and this level appears to be normal in those with CFS/ME

Meanwhile, the onset of FM frequently is traced to a physical or emotional trauma. The pain of FM gets better with heat and massage, while the pain of CFS/ME does not.

Conclusion

Does it even matter which diagnosis you get? In most cases it doesn't. Both illnesses can be treated with many of the same drugs and supplements, such as anticonvulsants. In most countries it is equally difficult to get disability benefits with either diagnosis. But if you do have CFS/ME, it is much more important to avoid excessive overexertion, as recovery could take weeks, months or even years.

It is also important to avoid confusion with other illnesses. Hypothyroidism can be misdiagnosed as both FM and CFS/ME, especially as most doctors do not realize that low normal thyroid hormone levels may not be adequate for everyone. There are many conditions that can cause pain and chronic fatigue, and some doctors may be too quick to make the diagnosis before overruling other possibilities.