There is no universally accepted explanation for fibromyalgia.
Theory of Central Sensitization
The theory of central sensitization says that persons with fibromyalgia have widespread pain due to increased sensitivity of the brain to pain signals. There is some stimulation of the person’s nerves that then causes an abnormal increase in neurotransmitters (chemical signals) that transmit pain. Over time, they react to signals that previously were not painful but now are interpreted as painful by the brain.
Other Possible Causes
1. Infection or post viral state: Some research suggests that fibromyalgia occurs after an individual is exposed to an infection. It may be caused by an abnormal immune response. This condition is not contagious.
2. Sleep disturbance: It is not clear whether a disturbance in sleep is the primary problem with persons with fibromyalgia or if it is just one of its symptoms.
3. Injury: Another theory suggests an injury or trauma may trigger the development of fibromyalgia. Fibromyalgia occurs in a significant number of persons with post-traumatic stress disorder (PTSD).
4. Abnormal autonomic nervous system: The autonomic nervous system is the part of the nervous system that controls involuntary functions like heart rate, blood pressure, breathing, sweating, and temperature regulation. Damage or dysfunction of the autonomic (more specifically, the sympathetic portion) may cause fibromyalgia. This damage to the sympathetic nervous system may cause persons to be more sensitive to different sensory stimuli like light, smell, sound, or touch. This means that a usually non- painful stimulus is perceived as painful.
5. Abnormal muscle metabolism: There may be a primary problem with the muscle or muscle metabolism. It may be related to local blood flow and may influence abnormal nerve activity.
6. Disorder of central processing with neuroendocrine or neurotransmitter dysregulation: Some research suggests there is an abnormal sensory stimulus processing that generates an abnormal pain response.
Some physiologic abnormalities in persons with fibromyalgia
1. Increased level of substance P in the spinal cord
2. Lower levels of blood flow to the thalamus in the brain
3. Hypothalamus-pituitary axis (HPA) dysfunction
4. Low levels of serotonin and tryptophan
5. Abnormal cytokine function
