ABSTRACT
Headache disorders are divided into two major categories. Secondary disorders have an identifiable underlying cause such as an infection, a brain tumor, or a stroke. Primary headache disorders have no apparent underlying cause (1,2). Of the primary headache disorders, tension-type headache is the most common in population studies (3), but migraine is most common among patients who seek medical care for headache (4). The most important forms of migraine are migraine with and without aura as well as a condition termed ‘‘probable migraine’’ (PM) (1).
