Chronic migraine and medication overuse.

Though clearly described as far back as the 17th century, chronic migraine has defied precise categorization and has continued to develop as an important diagnostic concept with significant societal impact. Worldwide prevalence is estimated to be between 1% and 3%, and these patients form a dynamic group cycling between chronic and episodic migraine. Theories of pathogenesis are developing supported by recent imaging and other findings. Of the many determinants of progression to chronic migraine, overuse of acute abortive headache medications may be one of the most important modifiable factors. Treatment strategies, in addition to educational measures, have included various preventive migraine medications such as topiramate, valproate, and onabotulinumtoxinA. CGRP monoclonal antibodies are efficacious for the management of chronic migraine both with and without medication overuse.