The autonomic nervous system rears its head in fibromyalgia – again. The pattern in fibromyalgia is now pretty clear; the fight/flight (sympathetic nervous system) system is activated even during rest, the heart rate response (chronotropic incompetence) to exercise is in the pits, and the sympathetic nervous system – overactive during rest – poops out when under stress. Plus the baroreflex response, which maintains blood pressure, and regulates autonomic nervous system functioning, is not working properly either.
The question at hand in this study is whether the baroreflex response problems really matter; are they some sort of benign artifact of the disease or are they hitting FM patients where it hurts – by causing them increased pain and reduced quality of life?
It’s an important question. As we’ll see many studies link autonomic nervous system problems to pain and other symptoms in fibromyalgia, but the ANS seems almost like an overthought in FM. Central sensitization; i.e., increased pain sensitivity due to problems with pain inhibition in the central nervous system holds sway. Given that a great deal of evidence suggests both are involved the two issues may very well be intertwined in some way. Few researchers have attempted to close that circle, however.
The Baroreflex Response
Without the baroreflex response you couldn’t stand without getting dizzy or fainting. The response involves nerves in the blood vessels near in and around the heart. Receptors called baroreceptors found on these nerves constantly (fractions of a second) monitor your blood pressure. When your blood pressure gets too high, baroreceptors inhibit the heart rate by turning down sympathetic nervous system activity. When it dips too low they send a message to the brain to increase the heart rate.
The baroreflex system is particularly important when the body has to immediately adjust to severe, potential falls in blood pressure during standing as gravity pushes blood to the lower part of the body. A simple misstep by the baroreflex can leave one feeling light headed and fatigued when one stands.
Studies suggest that baroreceptor problems may very well figure in the pain problems FM patients face as well. A 2010 study asserted that the role baroreceptors play in pain inhibition has been “well-documented”. It concluded that problems with cardiovascular control likely played a role in producing the pain problems FM patients face. Reduced baroreceptor activation in a 2015 study was associated with increased pain intensity in FM as well.
A faulty baroreceptor response, then, could play a role in both pain and problems standing and perhaps even exercise.
Are Problems Standing (and Remaining Standing) Common in Fibromyalgia?
That brings up one of the great unanswered questions (to my mind) in fibromyalgia. Are problems standing (dizziness, rapid heartbeats, increased pain and/or other symptoms) common in FM? We know these problems are common in chronic fatigue syndrome (ME/CFS) but what about FM? Have people with FM escaped the standing problems found in ME/CFS or have they somehow just passed notice in the medical field?
PLoS One. 2017 Jun 14;12(6):e0179500. doi: 10.1371/journal.pone.0179500. eCollection 2017.The degree of cardiac baroreflex involvement during active standing is associated with the quality of life in fibromyalgia patients. Zamunér AR1,2, Porta A3,4, Andrade CP1, Forti M1, Marchi A5, Furlan R6, Barbic F6, Catai AM1, Silva E1.
Now here we are in 2017 with orthostatic intolerance study that had FM patients stand for a period of time and while electrocardiogram, blood pressure, respiratory activity and autonomic tests ( fluctuations of heart period (HP), systolic arterial pressure (SAP), cardiac baroreflex sensitivity) as well as quality of life (FIQ: Fibromyalgia Impact Questionnaire) and pain (VAS: visual analogue score) were assessed.
The study had two major goals: document the baroreflex response problems in FM and determine if they were associated with increased pain and/or reduced quality of life.
The Study Results
The study suggested that the baroreflex problems in FM do indeed matter: FM patients with lower baroreflex activity had lower quality of life (FIQ questionnaire) scores and increased pain levels. Those results suggested that reduced baroreflex activity may inhibit FM patients from carrying out their daily activities (e.g. anything that involves standing).
More studies clearly need to be done but this study suggests that the orthostatic intolerance (increased symptoms while standing) may be common in fibromyalgia. Neither WebMd, Medical News Today, nor the Mayo Clinic lists problems standing as a major symptom. (Medical News Today lists dizziness as a secondary symptom.)
Evidence of orthostatic problems, however, showed up early a 1997 study finding that 60% of FM patients (but no healthy controls) exhibited a significant drop in blood pressure during a tilt-table test. Martinez-Lavin followed that up with a 1998 study highlighting the autonomic nervous system problems that popped up when FM patients stood.
A 2005 study found a high rate of fainting (44%) during a step-wise TILT test. I was unable to find any studies evaluating the incidence of postural orthostatic tachycardia syndrome (POTS: >30 heart rate increase upon standing), but Staud, in a 2008 review, claimed that POTS commonly showed up in tilt table tests in FM.
One other ME/CFS/FM takeaway of note: as in ME/CFS the associations disappeared during rest – like ME/CFS, FM studies need a stressor such as standing or exercise to bring out all the abnormalities present.
The Autonomic Nervous System Pain Connection
This isn’t the first study to suggest that autonomic nervous system problems are affecting the symptoms FM patients experience. Two studies indicate that indices of autonomic nervous system stress are strongly correlated with symptom severity. The authors suggested that problems with standing, tolerating warm temperatures, stressful events, sweating, dry eyes and/or mouth, light sensitivity, bladder and bowel problems, and even cognition could be associated with autonomic nervous system issues.
A 2015 study found a direct correlation between sympathetic nervous system activation and the amount of pain an FM patient was in. Another study concluded that “autonomic dysfunction is inherent in FM“.
Central sensitization has dominated the conversation regarding pain in FM but these studies suggest that autonomic nervous system needs to be taken into account as well.
Do you have orthostatic intolerance or autonomic nervous system dysfunction? Here are some common symptoms people with OI experience upon standing or remaining standing for longer periods
- Exercise intolerance
- Rapid heartbeats
- Feelings of anxiety
- Increased pain
- Vision problems (blurred vision, “white-outs,” black-outs)
- Hyperpnea (increased depth of breathing) or sensation of difficulty breathing or swallowing
- Sensitivity to heat
- Cognitive problems
It can help to ask yourself the following questions:
- Does sitting upright, standing or standing still for a period of time bother you?
- Do you feel the need to move around when you’re standing for a period of time?
- Do you feel better when sitting with your feet or a foot up or with your legs crossed?
- Are you tired after eating a meal?
- Do warm showers bother you? Do you do better in cooler showers?
- Does warm weather bother you?
There are several home tests you can take to determine if you have orthostatic intolerance or autonomic nervous system problems. Check them out in Health Rising’s Orthostatic Intolerance and Dysautonomia Diagnostic Resource Center.
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