Dysautonomia essentially means the autonomic nervous system is not working the way it should. Dysautonomia covers a myriad of symptoms, many of which are unpredictable and last for brief periods of time, sometimes less than a minute. Patients with fibromyalgia syndrome (FMS) may complain of light-headedness, especially with changes in their posture (standing up from laying down), heart palpitations that can be misinterpreted as anxiety related, sweating, constipation that is confused with irritable bowel syndrome, or diffuse, transient nausea. These changes correspond to dysfunctions within the ANS, essentially an imbalance between the sympathetic and parasympathetic systems.
In general, the dysautonomia of FMS exhibits continual ANS hyperactivity at rest but hypoactivity during times of stress. This dysautonomia is not taken lightly by many FMS researchers and physicians. One major researcher, Dr. Staud, has suggested that ANS dysfunction may be a contributing factor to the increased mortality of FMS patients.
Dysfunctions within the ANS of FMS patients have been investigated through several avenues. The first study was published in 1988 and used a pain management technique called stellate ganglion blocks. These numb the sympathetic nerves that go to the upper part of the body. When these were performed there was a significant reduction in upper extremity pain and tenderness compared to blocks that did not have any anesthetic in them which indicated that the sympathetic nerves were playing a major role in the pain process.
The degree of sympathetic activity was also tested in peripheral nerves through a variety of tests that looked at responses that could be measured on the skin. Without describing each test in detail, suffice it to say that each of these tests indicated that the sympathetic nerves were more hyperactive in FMS patients compared to normal patients. There is also a self-administered questionnaire, the Composite Autonomic Symptom Scale, COMPASS, with 73 questions in 9 categories that can assess symptoms consistent with autonomic dysfunction. When this was given to people with FMS it showed a correlation between the severity of FMS symptoms as measured by the Fibromyalgia Impact Questionnaire and the degree of symptoms consistent with dysautonomia.
There are also tests called heart rate variability analyses (HRVA). These measure the effects of the sympathetic and parasympathetic branches of the ANS and their effect on fluctuations in heart rate and specifically on oscillations in the intervals between consecutive heartbeats. Remember, the SNS speeds up the heart and the PNS slows it down. These two branches of the nervous system can make changes within fractions of a second. HRVA have shown that in FMS patients the normal “resting” tone of the heart rate is actually one that is influenced by slightly greater sympathetic activity and slightly decreased parasympathetic activity than found in people without FMS. However, the responses can be quite complex. For example, studies have shown that FMS patients show sympathetic effects to the heart and blood vessels that are enhanced when lying down but decreased when standing. This is thought to be due to the SNS not being able to respond that well to the receptors in the blood vessels (called the baroreceptors) that respond to postural shifts and tell the body that certain changes are necessary, for example, because gravity has now caused the blood to be pulled down into the legs.
There was a 2005 study that suggested that the dysautonomia of FMS patients is due to a persistently hyperactive sympathetic system that, for some reason, is now not that responsive to stress. This is not the case in people without FMS as the SNS is what generates the “fight or flight” response to stressful situations. It’s similar to having a car that is always running at a higher than normal speed so you have to keep applying the brakes just to drive, but is unable to accelerate rapidly if you need it to, for example, when you want to pass somebody on the road.
This hyperactivity may also explain the sleep disorders, intestinal irritability, and anxiety seen in FMS. That the hyperactivity may be unique to FMS was further substantiated when women with FMS underwent a 16 week resistance exercise training program. They had improvement not only in upper and lower body strength (increases of 63% and 49% respectively) but also a 39% decrease in pain perception and, most importantly, normalization of heart-rate variability.
The newest area of research concerns the night-time changes in the ANS, although these were first noted in 1998. Normally, nocturnal parasympathetic activity is greater than sympathetic activity however the situation is reversed in FMS and is thought to result in frequent arousals and sleep disturbances. More recent work in 2009 found significantly increased nocturnal sympathetic activity such that 10% of the 50 FMS patients studied had attacks of a heart rate called sudden onset supraventricular tachycardia. This is a condition in which the heart has a sudden outburst of activity where it suddenly begins beating very quickly. None of these patients had any pre-existing cardiac conditions and none of these attacks occurred in the normal patients in the study.
Dysautonomia may be in part responsible for the balance problems in FMS. Balance was one of the top ten most debilitating symptoms and reported by 45% of repondees in the internet survey conducted by the National Fibromyalgia Association in 2006. Another study found that 68% of 486 FMS patients had problems with balance. As the prevalence of FMS increases with age and affects primarily females, the risk of falls is not to be taken lightly in a population at high risk for hip fractures. The first study to actually quantitate the number of falls appeared in 2009 and followed 34 FMS patients with 32 age matched controls; compared to 6 falls in the controls FMS patients fell 37 times in a 6 month period.
Sympathetic hyperactivity may result in something called Raynaud’s phenomenon which has been noted in FMS patients for at least 25 years. Anywhere from 9% to 50% of FMS patients have some degree of Raynaud’s. Raynaud’s is a hyperactivation of the sympathetic nervous system that causes the peripheral blood vessels to close up, or vasoconstrict. The tissues then become hypoxic, leading to a bluish discolouration. It tends to occur in the fingers and toes. If it is severe, the damage can lead to pitting of the fingernails or toenails, even gangrene or necrosis of the tissues. It may be triggered by stress or cold.
If there is a dysfunction in the autonomic regulatory system postural changes may result in orthostatic hypotension, defined as a decrease in blood pressure of more than 20 mm Hg systolic or 10 mm Hg diastolic on standing for 3 minutes or more. Orthostatic hypotension is usually accompanied by only minimal changes in the heart rate. A more severe manifestation of dysautonomia is postural orthostatic tachycardia syndrome, or POTS, where the heart rate rises by more than 30 beats per minute; blood pressure either does not change or may even increase. The POTS associated with FMS is termed secondary POTS.
The impact of POTS can be significant, approaching a quality of life equivalent to patients with chronic obstructive pulmonary disease or congestive heart failure. The symptoms people experience are: a racing heart with postural changes, extreme fatigue, light-headedness, headache, an inability to tolerate even moderate activities, and cognitive difficulties. If your physician has a strong suggestion regarding POTS by a particular way they measure your blood pressure at an office visit the next step is a referral to a cardiologist who will order standardized methods to assess the orthostatic changes. These involve tilt table testing and may also include an electrocardiogram, a device called Holter monitoring that keeps a record of your heart rate over 24 hours, and plasma norepinephrine levels obtained from both supine and standing positions.
There are no FDA approved medications to help with the dysautonomia of FMS. As mentioned above, the best approach is exercise. Other lifestyle modifications such as adequate fluid intake to avoid dehydration, compression stockings and pacing to avoid fatigue remain the best alternatives.