• chronic migraine;
  • headache;
  • classification;
  • epidemiology;
  • nomenclature;
  • evolution

After nearly 3 decades of debate, the headache community still lacks globally accepted criteria for chronic migraine. This review summarizes the evolution of chronic migraine nomenclature and criteria. We concluded that although there are discrepancies in the currently proposed criteria, there is a significant amount of overlap with previously used classifications such that they all appear to describe the same subset of highly burdened migraine patients. In order to continue to understand the natural history of chronic migraine, address the unmet medical need, and develop effective therapies, field experts and physicians must have a classification that is well understood and accepted by the broader clinical community. It is our view that of the currently established classifications, the Silberstein and Lipton revised criteria for transformed migraine are the most applicable to daily clinical practice and field research.