In this study, researchers examined three groups of subjects—a set of 40 fibromyalgia (FM) patients, a set of 28 chronic low back pain (LBP) patients, and 14 healthy controls. All groups of subjects underwent a thorough laboratory examination.
The researchers found that FM patients had the most dysfunction in the stress response system, but that LBP patients had some of the same characteristics.
"From a clinical point of view, it is our impression that in individual cases FM, over the years, often ensues from LBP or other localized pain disorders...In view of the notion that patients with FM and LBP both experience chronic pain, that FM can develop after LBP, and that both disorders display rather similar neuroendocrine abnormalities (albeit to a different degree), one might conclude that the pain in FM is the primary factor underlying its pathogenesis."
What is clear from this study is that both FM and LBP patients exhibit disruption of the neuroendocrine system, especially in the system that controls how the body responds to stress. Similar dysregulation has been found in patients with PTSD, depression, and chronic fatigue syndrome.
Griep EN, Boersma JW, Lentjes EG, et al. Function of the hypothalamic-pituitary-adrenal axis in patients with fibromyalgia and low back pain. The Journal of Rheumatology 1998;25:1374-1381.