Our results demonstrated decreased overall resting-state functional connectivity of the 3 major intrinsic brain networks in women with CM, and these patterns were associated with frequency of moderate to severe headache and cutaneous allodynia.

Objective To investigate the intranetwork resting state fMRI connectivity within the Salience Network of chronic migraine with and without medication overuse headache. Methods We compared 351 pairs of intranetwork connectivity in chronic migraine (n = 13) and chronic migraine with medication overuse headache (n = 16) compared to matched controls, and between each chronic migraine subgroup. Results Compared to controls, 17 pairs of intranetwork connections in chronic migraine and 27 pairs in chronic migraine with medication overuse headache were decreased. When comparing chronic migraine with medication overuse headache versus chronic migraine, connectivity between bilateral extended amygdala, and between paracingulate to right ventral tegmental area/substantia nigra were decreased in chronic migraine (chronic migraine < chronic migraine with medication overuse headache). Connectivity between left dorsolateral prefrontal cortex to bilateral ventral striatum/pallidum, to bilateral dorsal anterior cingulate cortex; left anterior prefrontal cortex to contralateral orbitofrontal insula; and left ventral striatum/pallidum to ipsilateral supplementary motor area (SMA)/preSMA were decreased in chronic migraine with medication overuse headache (chronic migraine with medication overuse headache < chronic migraine). Conclusion Both chronic migraine subgroups had shared intranetwork connectivity abnormality, however, each subgroup had unique pattern of disruption within the salience network. The results suggest that the aberrant assignment of salience to external and internal stimuli plays an important role in chronic migraine and chronic migraine with medication overuse headache interictally, mostly involving mesolimbic pathways (especially bilateral extended amygdala) in chronic migraine, and prefrontal-subcortical limbic pathways in chronic migraine with medication overuse headache.

Background: The neural mechanisms of chronic migraine remain largely unknown but linked to the decreased connectivity to intrinsic brain networks. Objective: To characterize the intranetwork functional connectivity within the Central Executive Network (CEN) and Default Mode Network (DMN) in chronic migraine (CM), with and without medication overuse headache (MOH). Methods: Using functional magnetic resonance imaging, we performed post-hoc analysis of a total of 136 pairs of nodes to node functional connectivity (NTNC) within the CEN and 6 pairs of NTNC within the DMN in CM (n=13) and CMMOH (n=16) as compared to controls, and between these two subgroups. Results: Connectivity between right ventrolateral prefrontal cortex (PFC) to contralateral anterior thalamus and connectivity between left dorsal PFC/frontal eye field (FEF) to dorsomedial PFC were decreased within the CEN in both CM and CMMOH subgroups. In the CEN, there was more widespread disruption in the CMMOH (n=16) versus CM (n=13), when compared to healthy controls. Within the subgroups, connectivity between right inferior frontal gyrus to left dorsolateral PFC was decreased in CMMOH compared to CM. In the DMN, only one NTNC (left lateral parietal to precuneus/PCC) was disrupted in the CMMOH group when compared to controls. Conclusion: There are similar patterns of NTNC dysfunction within CEN in CM regardless of MOH status. We observed more extensive intranetwork disruption in CMMOH than CM. The decreased coherence between the right inferior frontal gyrus and the left dorsolateral PFC in CMMOH is likely associated with a significant disruption in the inhibitory control and a maladaptive response in risk aversion and reward; whereas the decreased coherence between right dorsolateral and ventrolateral PFC to contralateral dorsal PFC/FEF may be related to lack of cognitive control and top-down regulation of pain in both CM and CMMOH.