Restless Fibromyalgia?

Fibromyalgia is not the only chronic pain syndrome out there.  More and more keep cropping up.  Complex regional pain syndrome, irritable bowel syndrome, chronic functional abdominal pain, degenerative disc disease, chronic lower back pain, interstitial cystitis, myofascial pain syndrome, post-traumatic stress disorder, etc, etc…  From what I can tell, a lot of chronic disorders are intertwined.  People with fibromyalgia are likely to have chronic fatigue or restless legs syndrome too.  What is unclear is whether fixing one problem could fix any other problems that come along with it.

Restless legs syndrome (RLS) is one chronic pain disorder that is interesting to look at in comparison to fibromyalgia (see Goulart et al – they also have a very good description of pain mechanics).  An attempt to sum up how RLS and fibromyalgia overlap (in less than 2000 pages):

  1. Sleep deprivation or fragmentation.  The disruption of sleep patterns happens in both RLS and fibro.  RLS symptoms tend to flare at night.  Sleep disruption in fibromyalgia is a little less clear – definite chicken and egg question.
  2. Either way, sleep deprivation creates an increase in inflammation markers.
  3. This leads to a reduction in pain thresholds.  At this point is when “distortions” in pain perception begin in terms of pain duration, pain intensity, and even location of pain.

Dopamine is a strong connection between the two disorders, and looking at dopamine in terms of RLS clarifies some questions of how it connects in fibro:

  1.  Brain iron levels are reduced, which affects tyrosine hydroxylase, an enzyme that is important in the synthesis of dopamine.
  2. Reduced dopaminergic synthesis leads to overutilization of dopamine.
  3. Overutilization of dopamine leads to reduced dopaminergic transmission.
  4. Reduced dopaminergic transmission leads to the lack of pain modification by reduced O2 receptors.

According to Goulart et al, both syndromes begin with chronic pain:

⇒ Chronic pain
⇒ Perpetual activation of the hypothalamus-pituitary-adrenal axis
⇒ Increased levels of adrenaline and noradrenaline (synthesized from dopamine)

The dopamine connection between RLS and fibro means they share dysfunction in the same part of the brain: dorsal-posterior hypothalamus, serotonergic  dorsal raphe, neocortex, dorsolateral funiculus, intermediolateral nucleus.

Dopaminergic treatments and (get ready for it) N-methyl-D-aspartate receptor antagonists are possible treatments for RLS.  Since the two have so many distinct correlations, is it possible there can be overlapping treatment?

 

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