The last decade has brought significant improvements in brain imaging techniques, which can contribute to a greater understanding of migraine pathophysiology. Dr. Catherine D. Chong (Mayo Clinic) presented an Update on Migraine Imaging during the Hot Topics in Headaches and Related Disorders II: Migraine Pathophysiology, Brain Imaging and Therapeutic Advancesat the AAN 2019 Annual Meeting in Philadelphia. Dr. Chong and her team uses research-based structural and functional imaging techniques to gain better knowledge of the pathophysiology of migraine and other related headache disorders. During her lecture, Dr. Chong presented recent neuroimaging studies that evaluate the association of migraine with structural and functional alterations of brain regions commonly implicated in pain processing.1 Dr. Chong explained that the various migraine presentations—e.g. presence or absence of aura, associated cognitive dysfunction, sex differences, patient age, and disease burden—may be associated with discrete structural and functional imaging findings. In Dr. Chong's opinion, understanding these differences can help delineate the cyclic changes in headache pathophysiology.
Dr. Chong stressed that migraine is not a static state, but rather a highly dynamic disorder whose changes can be captured by different imaging techniques—e.g. functional Magnetic Resonance Imaging (fMRI) and Positron Emission Tomography (PET). Such changes in the migraine state include the hallmark hypersensitivities—e.g. sensitivity to light and sound—the different phases of a migraine attack, as well as the appearance of aura.
Showing data from a pivotal neuroimaging study, Dr. Chong described altered activity in the hypothalamic region before a migraine attack.2 Moreover, the hypothalamus showed stronger functional coupling to spinal trigeminal nuclei before the migraine attack, compared to stronger functional coupling to dorsal rostral pons during the attack. According to Dr. Chong, these observations indicate functional changes in hypothalamo-brainstem connectivity during the migraine cycle.
Dr. Chong further presented data from a recent study that investigated a novel methodology using diffusion tensor imaging (DTI) to detect subtle changes in fibertract integrity. The method consisted in measuring node-by-node parameters along each tract to compare fibertract profiles from patients with migraine and those with post-traumatic headache.3 This study showed distinct patterns in terms of mean diffusivity or radial diffusivity in several areas of the brain—e.g. uncinate fasciculi and left corticospinal tract. Furthermore, Dr. Chong explained that there was a significant positive correlation between headache frequency and fibertract injury patterns in patients with migraine; this correlation was absent in patients with persistent post-traumatic headache. According to Dr. Chong, these findings suggest possible differences in the neuropathological mechanisms underlying these two types of headaches.
Dr. Chong concluded that migraine neuropathology is highly complex, and can be seen as an interconnected pain-processing neural network. Ultimately, Dr. Chong was hopeful that the dynamic state of the migraine brain can be imaged and studied, which may help inform future therapeutic approaches.