Background - Chronic migraine (CM)can be associated with aberrant long-range connectivity of MRI-derived resting-state networks (RSNs). Here, we investigated how the fractal dimension (FD) of blood oxygenation level dependent (BOLD) activity maybe used to estimatethe complexity of RSNs, reflecting flexibility and/or efficiency in information processing in CM patients respect to healthy controls (HC).
Methods -Resting-state MRI data were collected from 20 untreated CM without history of medication overuse and 20 HC. On both groups, we estimated the Higuchi’sFD. On the same subjects,fractional anisotropy (FA) and mean diffusivity (MD)values of bilateral thalami were retrieved from diffusion tensor imaging andcorrelated with the FD values.
Results - CM showed higher FD values within dorsal attention system (DAS) and the anterior part of default-mode network (DMN), and lower FD values within the posterior DMN compared to HC.Although FA and MD were within the range of normality, both correlated with the FD values of DAS.
Conclusions - FDof DAS and DMN may reflect disruption of cognitive control of pain in CM.Normal microstructure of the thalamus and its positive connectivity with the cortical networking may be yet another evidence in supporting CM as a never-ending migraine attack.