Gray and White Matter Changes in Migraineurs: a Review of Literature

Several neuroimaging studies with advanced techniques have shown changes in gray and white matter in the brain of migraineurs. This narrative review highlights the structural and functional alterations and causality factors of migraine for the introduction of new treatment modalities. PubMed, Google Scholar, and Scopus were searched without any language restriction for the articles depicting gray and white matter changes in migraineurs. Using magnetic resonance imaging scans, multiple studies have demonstrated a reduction in white matter volume and presence of white matter hyperintensities and demyelinated white matter areas, especially in the frontal and parietal lobes. Similarly, voxel-based morphometry analysis has shown a greater reduction in gray matter in the frontal and cingulate cortex of chronic and episodic migraineurs. An overactivation of the frontal and cingulate cortex has been observed during the interictal period. These parts of gray matter are involved in cognitive, emotional, and autonomic aspects of nociception. Moreover, constituents of the limbic system, particularly the thalamus, hippocampus, amygdala, and cingulate gyrus, have also depicted predominant functional disturbances during migraine episodes. Recent studies highlighted a decrease in gray matter volume in the spinal trigeminal nucleus. These findings suggest that such changes might be the reason for dysfunction and pain regulation. Modern neuroimaging thus clearly helps in understanding the pathophysiology of migraine, which calls for novel therapeutic interventions in unresponsive or chronic migraineurs.