Cluster headache: what has changed since 1999?

The peripheral and central origin of pain in cluster headache (CH) and trigeminal autonomic cephalgias (TACs) has been matter of debate. In the last decade, a number of information came from both animal and human studies. This paper briefly highlights main data from these studies. Taken together, there is now sufficient body of evidence indicating that CH and TACs can be regarded as a unique headache spectrum-syndrome, due to involvement of specific brain areas.