Table 1 Classifications of chronic daily headache introduced in the mid-1990s

Mathew [12]

 1. Transformed migraine

 2. Chronic tension-type headache

 3. New daily persistent headache

Silberstein et al. [13]

 1. Transformed migraine

  1.1 With medication overuse

  1.2 Without medication overuse

 2. Chronic tension-type headache

  2.1 With medication overuse

  2.2 Without medication overuse

 3. New daily persistent headache

  3.1 With medication overuse

  3.2 Without medication overuse

 4. Hemicrania continua

  4.1 With medication overuse

  4.2 Without medication overuse

Manzoni et al. [14]

 1. Evolution of migraine

  1.1 Migraine with interparoxysmal headache

   1.1.1 Migraine with interparoxysmal headache fulfilling the criteria for chronic tension-type headache

   1.1.2 Migraine with interparoxysmal headache not fulfilling the criteria for chronic tension-type headache

  1.2 Chronic migraine

 2. Chronic tension-type headache