Longitudinal Changes in Brain Volume and Magnetic Susceptibility Following CGRP Monoclonal Antibody Treatment in Patients With Migraine

Objective The aim of this study was to evaluate cross‐sectional and longitudinal changes in brain volume and magnetic susceptibility associated with treatment using calcitonin gene–related peptide monoclonal antibodies in patients with migraine. Background Calcitonin gene–related peptide monoclonal antibodies are effective in migraine prevention. However, because their primary action is peripheral, the extent of their influence on the central nervous system remains unclear. Methods Twenty‐eight patients with migraine (18 responders and 10 nonresponders) underwent magnetic resonance imaging before and 6 months after treatment. Voxel‐based analyses were performed using three‐dimensional T1‐weighted images and quantitative susceptibility mapping to assess brain volume and magnetic susceptibility, respectively. Cross‐sectional analyses compared responders and nonresponders at each time point, whereas longitudinal analyses used subtraction images to evaluate alterations between pre‐ and post‐treatment conditions. Results Cross‐sectional analyses revealed no significant differences in brain volume or magnetic susceptibility between responders and nonresponders at either time point. Longitudinal morphometric analyses did not identify correction‐surviving changes in gray matter volume or cortical thickness. At an exploratory voxel‐level threshold, responders showed a greater longitudinal increase in magnetic susceptibility than nonresponders in the right calcarine sulcus extending into the visual association cortex ( T = 4.24; MNI coordinates: x = 28, y = −68, z = 9), although this finding did not survive correction for multiple comparisons. Conclusion Calcitonin gene–related peptide monoclonal antibody treatment was not associated with correction‐surviving structural morphometric changes over 6 months. An exploratory right calcarine susceptibility finding was observed in clinical responders, but its clinical significance remains unclear. These findings should be considered preliminary and require validation in larger longitudinal studies.