Although recent imaging studies of fibromyalgia (FM) have converged on a dysfunction of central pain processing as the primary pathophysiologic cause of the disorder, microstructural changes of the white matter (WM) suggestive of abnormalities in the anatomic connectivity of the brain have not been extensively examined. The aim of this study was to investigate WM integrity and its possible relationship to pain symptoms in women with FM.
Nineteen FM patients and 21 age-, sex-, and education-matched healthy control subjects were included in the study and underwent diffusion-weighted imaging. Group differences in WM integrity, which were assessed via fractional anisotropy (FA), was investigated by applying tract-based spatial statistics.
As compared with the healthy control group, the FM group showed a single cluster with lower FA in the left body of the corpus callosum, which was found to be connected to the bilateral sensorimotor cortices (P < 0.05, corrected for multiple comparisons). Furthermore, FA values in the cluster were negatively associated with sensory pain, as measured by the Short-Form McGill Pain Questionnaire, as well as with the relative magnitude of sensory pain versus affective pain (calculated by dividing the sensory score by the affective score).
Findings of the current study demonstrated that patients with FM had disrupted WM microstructure in the body of the corpus callosum, which was associated with clinical pain intensity. Our results suggest that abnormal interhemispheric transfer might contribute to the heightened pain perception. Our findings further strengthen the hypothesis of centrally augmented pain processing in patients with FM.