Chronic headaches: from research to clinical practice

Chronic daily headache(CDH) is a heterogeneous group ofheadaches that includes primaryand secondary varieties. PrimaryCDH is a frequent entity that probablyaffects 4–5% of the population.It can be subdivided intoheadaches of short duration (<4h/attack) like chronic clusterheadache, and disorders of longduration (>4 h/attack). PrimaryCDH of long duration includestransformed migraine, chronic tension–type headache, and new dailypersistent headache and hemicraniacontinua. Analgesics, ergots andtriptan overuse are frequent in alltypes of CDH. We revise recentinsights into the epidemiology,pathophysiology, clinical characteristicsand prognosis of CDH.