Chronic daily headache (CDH) is not a specific headache type, but a syndrome that encompasses other primary headaches. The term “chronic” refers either to the frequency of headaches or to the duration of the disease, depending upon the specific headache type.
●With headache subtypes of long duration (ie, four hours or more), “chronic” indicates a headache frequency of 15 or more days a month for longer than three months in the absence of organic pathology. These headache subtypes are:
•Chronic migraine headache
•Chronic tension-type headache
•Medication overuse headache
•New daily persistent headache
●With headache subtypes of shorter duration (ie, less than four hours), “chronic” refers to a prolonged duration of the condition itself without remission. The headache subtypes in this category are the following:
•Chronic cluster headache
•Chronic paroxysmal hemicrania
•Short-lasting unilateral neuralgiform headache attacks
•Primary stabbing headache
●The worldwide prevalence of CDH among adults is approximately 4 percent. Most patients with CDH have either chronic tension-type headache or chronic migraine.
●The diagnosis of CDH is suspected on the basis of a compatible headache history. Other disorders causing secondary headache must be excluded.
●The management of CDH depends on the specific headache type and the presence or absence of medication overuse.