Of all the painful states that afflict humans, headache is undoubtedly the most frequent and common reason for seeking medical help. Headache has over 300 different types and different etiologies; migraine is one of them and continues being an under diagnosed condition in many of cases as it can be accompanied by symptoms commonly associated with other causes of facial pain. Out of 28 million people in USA who have history of headache and symptoms which mimic the typical migraine only 48% are diagnosed of migraine.
Nasir, Sadaf; Abrar, Naureen; Sher, Khalid; and Shahnaz, Shahnaz
"Frequency of cranial autonomic symptoms (cas) in migraine patients,"
Pakistan Journal of Neurological Sciences (PJNS): Vol. 11
, Article 4.
Available at: http://ecommons.aku.edu/pjns/vol11/iss2/4