Figure 1From: Epidemiological profiles of patients with chronic migraine and chronic tension-type headache Flow chart of the study population. Legend: CH = chronic headache, CM/EM = chronic/episodic migraine, CTTH/ETTH = chronic/episodic tension-type headache, CM+CTTH / EM+ETTH = chronic / episodic migraine with concomitant tension-type headache.Back to article page