Brain structural network modular and connectivity alterations in subtypes of patients with migraine and medication overuse headache

Migraine, one of the most prevalent and debilitating neurological disorders, can be classified based on attack frequency into episodic migraine (EM) and chronic migraine (CM). Medication overuse headache (MOH), a type of chronic headache, arises when painkillers are overused by individuals with untreated or inadequately treated headaches. This study compares regional cortical morphological alterations and brain structural network changes among these headache subgroups. Sixty participants, including 20 in each of the following patient groups (EM, CM, MOH), and healthy controls (HC) completed the study. Our results show that the EM group exhibited cortical thickness (CTs) thinning predominantly in the left limbic, whereas CM patients exhibited CTs thinning across both left and right hemispheres. The MOH group demonstrated the most widespread CTs thinning. Both CM and MOH exhibited comparable patterns of CTs thinning within lobes, leading to reduced intra-lobe connectivity. While there were no significant differences in total inter-lobe connectivity between migraine groups and HC, both CM and MOH groups exhibited significantly decreased inter-limbic connectivity compared to HC and EM groups. In addition, they showed increased inter-frontal and inter-parietal connectivity, suggesting possible compensatory mechanisms to offset the loss of inter-lobe connectivity between the limbic and other lobes. Both CM and MOH groups exhibited a significant loss of global efficiency and a decrease in betweenness centrality in their brain networks, with MOH showing the most pronounced decrease and CM showing the second largest decrease. Our results suggest that aberrant structural brain networks in CM and MOH are less efficient, less centralization, and abnormally segregated.