Functional magnetic resonance imagery (fMRI) in fibromyalgia and the response to milnacipran

Abstract

Functional imaging has been used to study response to pain in fibromyalgia patients. Functional magnetic resonance imagery (fMRI) which tracks local changes in blood flow has a higher spatial and temporal resolution than other techniques such as positron emission tomography (PET) or single-photon emission tomography (SPECT). fMRI studies in fibromyalgia patients suggest that similar levels of subjective pain result in similar central nervous system (CNS) activation in both fibromyalgia patients and controls. For a similar stimulus, however, fibromyalgia patients have a greater subjective sensation of pain. This increased sensitivity is accompanied with a decreased activity in brain regions implicated in the descending pain inhibitory pathways. The hypothesis that increased sensitivity to pain is due to decreased activity of the descending inhibitory pathways is supported by results with milnacipran. Fibromyalgia patients treated with the serotonin and noradrenaline reuptake inhibitor, milnacipran, exhibited a reduction in pain sensitivity and a parallel increase in activity in brain regions implicated in the descending pain inhibitory pathways compared to placebo-treated patients.