Chronic migraine
Chronic tension type headache
New daily persistent headache
Hemicrania continua
In most of the cases the cause of chronic daily headache is unknown,
in some cases however underlying causes like inflammation of
cerebral blood vessels, meningitis, high or low ICP, pinched nerves in the back, brain tumor and traumatic brain injury have been identified.
Treatment is mainly with antidepressants, beta blockers, anti seizure medications, and NSAIDS.
http://www.mayoclinic.