Diagnosis of Primary Chronic Daily Headaches

Abstract

Chronic daily headache (CDH) is a term of art meaning headaches present at least 15 days/month, at least 4 h/day treated or untreated, for at least 3 months.

CDH is generally primary, but many clinicians include medication overuse headache (MOH) in the term. CDH is not a diagnosis in the International Classification of Headache Disorders. The four primary CDHs are: chronic tension-type headache (CTTH), hemicrania continua (HC), new daily persistent headache (NDPH), and chronic migraine (CM).

CTTH is a low-level featureless headache, almost never with impact. HC is a unilateral, mild to moderate headache with periodic severe exacerbations, accompanied by autonomic signs. HC is defined by its indomethacin responsiveness. NDPH is best diagnosed as abrupt onset of a primary CDH with any phenotype. Primary CM is a primary CDH in which a patient transforms from episodic migraine to CDH without secondary causes, thereby excluding medication overuse. MOH is not a primary CDH; it is characterized by overuse of enough acute medication to transform a patient to secondary CDH. The Food and Drug Administration (FDA) defined “chronic migraine” as CDH, both primary and secondary.