The etiology of fibromyalgia is unclear, but evidence suggests that it is a heritable disorder. The etiology of fibromyalgia is now thought to be due to a combination of several factors associated with the presence of both chronic pain and affective disorders, similar to those postulated in irritable bowel syndrome, chronic fatigue syndrome, major depressive disorder, temperomandibular joint disorder, and tension and migraine headaches. The factors include genetic factors, aberrant pain processing in the central nervous system, abnormalities in the neuroendocrine system, and specific triggers in the environment.
Genetic relationships have been found between fibromyalgia and several genes, including genes encoding proteins in neurotransmitter signaling, catechol-O-methyltransferase, and dopaminergic signaling. Patients with fibromyalgia have enhanced sensitivity to several stimuli including heat, pressure, and sound. Patients with fibromyalgia have been noted to have lower pain thresholds than controls. The levels of central neurotransmitters such as serotonin,
N. Vadivelu et al. (eds.), Essentials of Pain Management,
DOI 10.1007/978-0-387-87579-8_25, © Springer Science+Business Media, LLC 2011
norepinephrine, and dopamine have been noted to be lower in patients with fibromyalgia as compared to rheumatoid arthritis or healthy controls. In addition, there are possibly elevated levels of excitatory amino acids, neurotrophins, and substance P in the cerebrospinal fluid (CSF) seen in patients with fibromyalgia. Some researchers have suggested that there may be activation in the neuroendocrine axis, namely the hypothalamic-pituitary-adrenal axis. There appears to be increased activity of the sensory inputs in these patients as well, contributing to increased pain perception.
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