Brain activity monitoring supports phases
Citing imaging studies in his own laboratory, Todd J. Schwedt, MD, chair of neurology research, Mayo Clinic, Phoenix, substantiated several of the points made by Dr. Goadsby in a separate talk he made on migraine phases. By monitoring brain activity during each phase of migraine, he suggested his data support the role of CGRP in producing an inflammatory response as well as sensitizing the trigeminal cervical system in steps that appear to be important to the pain process.
Mitchel L. Zoler/MDedge News
Dr. Todd J. Schwedt
Dr. Schwedt showed several pieces of evidence suggesting that CGRP is an early mediator even if it is not necessarily the first step in a process for every patient. However, like Dr. Goadsby, Dr. Schwedt also acknowledged that the interplay between events is complex and might differ between patients.
Yet, he says that brain activity on imaging is not the only evidence of the role of CGRP activation early in the process leading toward migraine.
“I am a little biased towards imaging, but it’s not just about imaging,” Dr. Schwedt said.
“If we look at preictal salivary CGRP levels and then follow them into the headache phase, we see the levels increase, but they go back to normal a couple of hours into the attack and then stay normal, presumably, until the patient gets closer to the next attack,” Dr. Schwedt said.
Despite progress there is more to be done to determine why CGRP is released and whether it can be inhibited early to abort migraine before the headache phase, but both Dr. Goadsby and Dr. Schwedt pointed to this as a very early event. This is not to say that others, such as cortical spreading depression, do not have an equally important role in the evolution of migraine, but each expert considers migraine phases to be useful divisions for tracing the sequence of pathogenic events.
The phase of a migraine attack and their corresponding symptoms “can be mapped to altered brain function and release of neuropeptides and neurotransmitters,” Dr. Schwedt said. The implication is that better targets for blocking migraine before it reaches the headache phase might be discovered in these early phases.
Dr. Goadsby and Dr. Schwedt listed more than 10 pharmaceutical companies to which they have financial relationships, but both claimed that none of these relationships posed a potential conflict of interest.