Demographic and clinical characteristics of patients with episodic migraine versus chronic daily headache.

We compared data from 243 patients with episodic migraine (EM) and 132 patients with chronic daily headache (CDH). We divided the latter group into those with tension-type headache only (CDH Type 1) and those with headaches having migrainous features (CDH Types 2 + 3) and compared each with the EM group and all three groups with one another. CDH Type 1 patients differed from those in the other groups by virtue of gender (more often male) and mean age at headache onset (older). The CDH Types 2 + 3 and EM groups differed only in that the former were more likely to have undergone a brain-imaging study. These data suggest that CDH Type 1 may represent a distinct headache syndrome, while CDH Types 2 + 3 closely resemble episodic migraine.