New daily persistent headache: controversy in the diagnostic criteria.

New daily-persistent headache is a relatively uncommon type of chronic daily headache. The critical features of the original description and the subsequent Silberstein-Lipton description was the onset:  daily headache starts abruptly without a background of frequent or worsening headache. In 2004, the International Headache Society classification committee excluded an abundance of migrainous features. The exclusion of patients with too many migrainous features from the International Headache Society classification was contentious from the onset and is a source of consternation for many headache experts. Many contend that the sudden onset of a daily headache raises the same issue of what turned on the headache, irrespective of the headache features. Switch-related questions about predisposing factors or precipitating events are equally valid regardless of how many migrainous features the patient has. The differential diagnosis, treatment response, or prognoses do not vary by the number of migrainous features. The current International Headache Society definition excludes more than half of patients with new onset of daily headache. This exclusion due to migrainous features could have adverse scientific, diagnostic, and treatment consequences.