Studies in fibromyalgia syndrome with functional neuroimaging support the hypothesis of central pain augmentation. To determine whether structural changes in areas of the pain system are additional preconditions for the central sensitization in fibromyalgia we performed voxel based morphometry in patients with fibromyalgia and healthy controls.
We performed 3 Tesla magnetic resonance imaging of the brain in 14 patients with fibromyalgia and 14 healthy controls. Regional differences of the segmented and normalized gray matter volumes in brain areas of the pain system between both groups were determined. In those areas in which patients structurally differed from healthy controls, the correlation of disease-related factors with gray matter volumes was analyzed.
Patients presented a decrease in gray matter volume in the prefrontal cortex, the amygdala, and the anterior cingulate cortex (ACC). The duration of pain or functional pain disability did not correlate with gray matter volumes. A trend of inverse correlation of gray matter volume reduction in the ACC with the duration of pain medication intake has been detected.
Our results suggest that structural changes in the pain system are associated with fibromyalgia. As disease factors do not correlate with reduced gray matter volume in areas of the cingulo-frontal cortex and the amygdala in patients, one possible interpretation is that volume reductions might be a precondition for central sensitization in fibromyalgia.
ACC = anterior cingulate cortex;
fMRI = functional magnetic resonance imaging;
FMS = fibromyalgia syndrome;
HADS = Hospital Anxiety and Depression Scale;
PAG = periaqueductal grey;
PDI = Pain Disability Index;
PTSD = posttraumatic stress disorder;
ROI = region of interest;
SPM = statistical parametric mapping;
SSRIs = selective serotonin reuptake inhibitors;
TCAs = tricyclic antidepressants;
VBM = voxel-based morphometry;
3T = 3 Tesla.