Interictal burden attributable to episodic headache: findings from the Eurolight project

Background Most primary headachesare episodic, and most estimates of the heavy disability burden attributed to headachederive from epidemiological data focused on the episodic subtypes of migraine and tension-type headache(TTH). These disorders give rise directly but intermittently to symptom burden. Nevertheless, people with these disorders may not be symptom-free between attacks. We analysed the Eurolight dataset for interictal burden.