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.
Keywords: Central executive network; Chronic migraine; Default mode network; Functional MRI; Medication overuse headache.