The tension headache component of chronic daily headache.

Chronic daily headache (CDH) is an overarching term that includes multiple types of frequent primary headaches that are not trigeminal-autonomic cephalgias. The components of typical CDH can be divided into a more severe or "big" headache and a less severe or "little" headache. The big headaches tend to have features of migraine while the little headaches have features of tension-type headache (TTH). Whether this represents a spectrum or continuum or whether it is the superimposition of two unique headache entities is open to debate. For subjects with big and little headache, the concept that the TTH component is part of a spectrum seems likely. Subjects with only TTH and no migrainous component seem to represent a different entity, pure chronic TTH. These patients have a daily moderate headache that is poorly responsive to current therapies and appears to be a different TTH than the migraine tension type of CDH. The TTH component of CDH may represent multiple subdivisions of TTH.