Functional connectivity changes within the salience network in patients with chronic migraine

Background: Migraine is a common neurological disorder whosepathogenesis is still unclear, especially when it occurs in its chronicform. The aim of the present study is to investigate functionalconnectivity within the salience network (SN) and the default modenetwork (DMN) in episodic migraine (EM) and chronic migraine (CM),in order to identify any functional brain connectivity changesassociated with chronicization.Methods: Patients consecutively referring to the Regional HeadacheCentre of L'Aquila with a diagnosis of migraine were screened forthe inclusion in the study. The diagnosis of EM or CM was madeaccording to the criteria of the International Classification ofHeadache Disorders (ICHD-III beta version). Twenty-four women withEM (mean age 45.5±8.7) and 24 women with CM (mean age 45.8±9.0) were included. Patients underwent a neuroradiological assess-ment through a 3 Tesla Magnetic resonance Imaging (MRI) scanner(Discovery MR750w). Resting-State fMRI data were analysed bymeans of a seed-based approach, using four and six different seeds,sampling the main hubs of the DMN and SN respectively.Results: Alterations in functional connectivity were found in patientswith CM as compared to patients with EM in the SN. Specifically,alterations involved the salience network between the left anteriorinsular cortex and the midcingulate cortex (p=0.0001) and the rightsupramarginal gyrus (p=0.0005). Further alterations were found inthe connectivity between the right supramarginal gyrus and the leftfrontal operculum (p=0.0005). Discussion: Our findings suggest that the SN, which is involved in theintegration of sensory, emotional and cognitive information, may bedysregulated in patients with CM, especially in its crucial hubsrepresented by the anterior insula and the cingulate cortex.Dysfunctional connection among cortical hubs deserves furtherinvestigation in order to better understand migraine pathogenesisand to develop effective treatment strategies.