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Possible Causes

Peripheral Systems

You have many systems and structures that may be sending distress signals to your central nervous system (CNS) about what is happening throughout your body. For the most part, your CNS also communicates with these various systems and structures in your body in its effort to exert control over them. As you read about the various systems affected by fibromyalgia, keep in mind that there is an interplay to and from the CNS.

Autonomic Dysfunction

The main neurological interface between your CNS and all your organs and tissues is your autonomic nervous system. Half of this system is overly controlling while the other part is not doing its job. The result is a serious imbalance that contributes to a variety of fibromyalgia symptoms. Read more.

Immune System

Your immune system produces all sorts of substances to protect your body from infections and help it heal. It’s a highly adaptive system that responds rapidly to the environment.

Studies involving fibromyalgia patients indicate that there are elevated levels of various immune system cytokines (chemicals that the immune system uses to communicate with your neurons, CNS, and other tissues). Some of the more common ones are interleukin-6 or IL-6 and interleukin-8 or IL-8, but there are others.1 These elevated cytokines are thought to reflect some form of low-level inflammation, but the exact source is still being explored.

One theory is that bacterial products from the gut are escaping through the GI lining and getting into the bloodstream. Naturally, this would trigger the immune system into action. Two studies have shown enhanced gut permeability in fibromyalgia to lend credibility to this theory.2,3 In addition, the most recent study showed that digested bacterial particles from the gut are elevated in the blood, along with several cytokines and antibodies.

Although there are no signs that the peripheral immune system is attacking any organs or tissues, it appears to be chronically activated. More research is needed to characterize the role of the immune system, but the substances it produces may be linked to pain, disturbed sleep, and fatigue. Cytokines can also trigger the activation of immune cells in the CNS, in addition to causing hormonal and metabolic alterations.

Hormonal Fatigue

Your adrenal glands produce adrenaline and cortisol, which should help keep you alert and ready to go each morning, but they are both low in fibromyalgia. Why does this happen and what does it mean for you? Read more.

Altered Metabolism

Maintaining a healthy weight is hard enough when you have a chronic condition like fibromyalgia that impairs your ability to exercise. There is a reason you may struggle with weight and it is partly due to problems with the immune system and partly due to insulin changes. Read more about your metabolic alterations.

Gut Influences

Your GI system doesn’t just digest your food. The bacteria that reside in your gut control your cognitive functions, your mood, and in fibromyalgia, they are tied to your pain. The gut in fibromyalgia has undergone changes that are impacting how you feel. Read more.

Hyped-Up Ganglia

Before any neurological signal enters the spinal cord, it must pass through a bulb-shaped structure called the dorsal root ganglia. In fibromyalgia, these ganglia seem to be ramping up the intensity of the signals entering the cord. Why this might be happening is unclear, but these structures located up and down the spinal cord are greatly influenced by the immune system and the processes in the gut. Read more.

Sensory Nerve Loss

Throughout the skin there are tiny nerve fibers that pick up information and transmit it to the spinal cord. In roughly 40 percent of fibromyalgia patients, there is a reduction in the number of these small fibers located in the skin. The contribution of this finding to CNS function is unclear because the severity of symptoms does not differ between those patients with nerve fiber loss and those without. Yet, it may help explain why some patients have mild numbness sensations in their extremities.

The cause of the nerve fiber loss is unknown. Best guess is that it’s a compensatory mechanism by the body to reduce the number of noxious inputs to the CNS. The significance of this finding is still being explored.

Knotted Muscles

AFSA-funded studies show that all fibromyalgia patients have active myofascial trigger points (or MTPs) in the muscles throughout their body. MTPs can be felt as firm nodules or knots in the muscles, and they cause radiating pain and restricted movement. MTPs generate a constant trickle of noxious signals to the spinal cord. This can aggravate the dysfunctional CNS state (and your symptoms), but MTPs do not cause fibromyalgia. However, treating them can greatly reduce your pain and minimize the sleep disturbances caused by the constant arousal signal they generate.

Exercising a muscle with an MTP causes the muscle to fatigue four times faster, so in addition to their pain-generating symptoms, these knots can cause a profound sense of muscle fatigue. See our section on Muscle Pain Relief to learn how to get your MTPs treated.

Sex Hormones

More women than men get fibromyalgia, so does it have anything to do with sex hormones? Possibly. The female predominance of fibromyalgia only emerges after puberty. Along these same lines, pain thresholds are the same for boys and girls, while a reduction in pain threshold develops after puberty.

Studies show testosterone reduces the impact of pain in both men and women, although this hormone is much higher in men. In menstruating women, the pain-inhibitory system is most effective during ovulation when estrogen is high and progesterone is low. Sex hormones also influence the developing brain and how it responds to painful stimuli later in life. However, hormones alone cannot fully account for the higher prevalence of fibromyalgia in women.

1. Peck M, et al. Cureus 12(9):e10276, 2020. Free Journal Report
2. Goebel A, et al. Rheumatology 47:1223-7, 2008.
3. Martin F, et al. Frontiers Immunol 14:1253121, 2023. Free Journal Report