The evidence for central nervous system dysfunction in fibromyalgia is clear: the ascending pain producing pathways are overly activated, while the descending pain inhibitory pathways are under-activated. This results is people with fibromyalgia experiencing pain where no injury or sign of damage exists.
Problems with the peripheral nervous system in the body also exist. The nerve fibers that carry pain signals to the brain are overly activated, and some of the small, unmyelinated nerves in the skin and the eyes that carry sensory information to the spinal cord and brain are damaged in some patients.
Corneal Nerve Problems……Check!
The nerve fibers in the corneas of the fibromyalgia patients’ eyes were shorter than normal in 44% of the patients, and nerve fiber density and branching was reduced in 10% and 20% of the patients, respectively. All told, just over 50% of the FM patients displayed one or more indications of small fiber pathology.
Quantitative Sensory Testing (QST)
The QST testing involved exposing FM patients to things like cold, heat, pressure, and pin-pricks. The results indicated that many patients showed signs of allodynia or increased pain sensitivity in one or more tests. In particular, FM patients showed a marked sensitivity to pressure tests.
Allodynia and Increased Sensitivity to Pain (% experiencing) – these tests measured the response to a painful stimuli.
- Mechanical pain – 21%
- WInd-up (increased pain sensitivity as the duration of the pain stimulus increases) – 26%
- Pressure – 69%