Headache screening and diagnosis.

In most cases, diagnosis of the various headache subtypes is possible through the accurate collection of medical history data. However, sometimes serious problems of differential diagnosis may be encountered. Therefore, the distinction between migraine without aura and tension-type headache is not always easy, the relationship between chronic migraine and medication overuse headache is a complex one, and differentiation of chronic tension-type headache vs. new daily-persistent headache is often problematic. A clear knowledge of the distinctive clinical features of the various headache subtypes is necessary to establish a correct diagnosis in the group of unilateral headaches with short-lived attacks and in the group of headaches with nocturnal onset.