Chronic migraine and chronic tension-type headache: different aspects of the chronic daily headache spectrum. Clinical and pathogenetic considerations

Clinicians working in the field of headache face great difficulty in managing patients with daily headache. Many of these patients have a history of episodic migraine that over several years has transformed into a chronic headache. Others have a history of episodic tension-type headache that also has chronicized. Still others present clinical characteristics that resemble both headache forms. In this article, we review the clinical and pathophysiological aspects of chronic daily headache and discuss the problems associated with its diagnosis.