Both the central nervous system and the peripheral nervous system are heavily involved in starting and continuing a migraine attack, and are involved before the migraine even starts. If you divide a migraine into premonitory phases–the aura, the migraine phase and then the postdrome, with modern technology including functional MRI and PET scans, we observe that there are different parts of the brain, both peripherally and centrally that are involved in each part of these attacks. For example, in the prodrome, people will experience yawning or feeling tired or being very light-sensitive or sound-sensitive before they even have a headache attack. And during that time, imaging of the brain can show us that some parts of the hypothalamus, the brain stem, the thalamus, and even the cortex can be involved in the process. When the aura occurs, which we think is more of a cortical spreading depression, we usually see cortical changes occurring on these functional MRIs and PET scans. And then during the pain attack itself, we see changes that are occurring inside the brain and the nerves around the head, and people develop allodynia where even touching the head will be painful and that is another process that is occurring both centrally and with connections to the peripheral nervous system. And then after the pain has left, there’s a postdrome period and we really haven’t studied that as much; it’s clear that that also has brain connections.
In chronic migraine just as in chronic pain, we're always looking for new treatments that can alleviate the suffering of patients that have not had success with our traditional treatments and we're undergoing a kind of mini revolution with the discovery that antibodies to calcitonin gene-related peptide and associated receptors can actually prevent migraine attack. Several pharmaceutical companies now are working on these new compounds which I think are going to open up a whole new avenue for some people with chronic migraine. In summary, I want to say migraine and chronic migraine are primary care disorders, and we need to deputize every person and provider primary care to work with people with migraine. It's a primary care disorder and we need every primary care provider to understand that it's a real condition, it has physiology and anatomy that's anchored in brain function, and that they too can become treaters and preventers of chronic migraine.