Brain Regions Involved in Fractional Amplitude of Low-Frequency Fluctuation in Cluster Headache Patients: A Resting-State Functional MRI Study

Background: A limited number of studies have reported on fractional amplitude of low-frequency fluctuation (fALFF) in cluster headache (CH). We used resting-state functional magnetic resonance imaging (RS-fMRI) to assess the possible pathogenic role of fALFF in CH. Methods: RS-fMRI scans of 23 patients with CH were obtained (11with left-sided headache and 12 with right-sided headache), along with scans of 23 age- and sex-matched normal controls. The RS-fMRI data were analyzed to explore abnormal brain activity in the left CH and right CH patients during the non-painful state of cluster period. fALFF was compared between patients and controls, and correlation analysis between the regional mean fALFF values and clinical characteristics was performed. Results: A decrease in fALFF was detected in the left cerebellum, left lentiform nucleus, left frontal lobe, left anterior cingulate, and right postcentral gyrus in the left CH group compared to the controls, while a decrease of fALFF was detected in the right cerebellum, right cingulate gyrus, right superior parietal lobule, right inferior parietal lobule, right postcentral gyrus, and left precuneus in the right CH group. No patient had a region with increased fALFF. A moderate correlation was observed between some regional mean fALFF values and the clinical characteristics. Conclusions: We deduced that dysfunction in multiple brain areas is involved in the non-painful state of CH during cluster period. Several functional networks are involved, such as the default-mode, cerebellar, and somatomotor networks, suggesting that CH is the result of abnormal functioning in multiple brain functional networks.