Most simply stated, chronic daily headache (CDH) is headache that occurs 15 or more days a month.
Doctors divide chronic daily headache into a number of subcategories:
* Primary CDH: not attributable to an underlying disorder
o Shorter than four hours duration
+ chronic cluster headache
+ chronic paroxysmal hemicrania
o Longer than four hours duration
+ chronic tension-type headache
+ chronic Migraine (sometimes called transformed Migraine)
+ new daily persistent headache
+ hemicrania continua
* Secondary CDH: attributable to an underlying disorder
o post-traumatic headache
o attributable to cervical spine disorders
o associated with vascular disorders such as arteriovenous malformation, arteritis, subdural hematoma
o associated with nonvascular intercranial disorders such as intracranial hypertension, infection, or neoplasm
Studies have also shown that CDH patients were more likely to snore and report problems with sleep than episodic headache and Migraine patients.